GB2025673A

GB2025673A - Desired velocity control for railway vehicles

Info

Publication number: GB2025673A
Application number: GB7921710A
Authority: GB
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1978-06-28
Filing date: 1979-06-21
Publication date: 1980-01-23
Also published as: GB2025673B; DE2926150A1; MX147629A; BR7904070A

Abstract

The control system includes programmed micro-processor control apparatus for determining a desired velocity or reference velocity for the railway vehicle to follow at all times under automatic control. The reference velocity is selected as the lower of an input command velocity, which can be modified by a cut out car or performance restricted condition, and a programme step velocity signal. The reference velocity is then compared with the central velocity to provide a tractive effort signal. The provision of a start up enable signal is also described. <IMAGE>

Description

SPECIFICATION Desired velocity control for passenger vehicles The present invention generally relates to automatic control of passenger vehicles, such as mass transit vehicles and the like, and more particularly to such vehicles which also need speed control and speed maintenance while moving along a track.

As background prior art, an article entitled The BARTD Train Control System published in Railway Signaling and Communications for December 1967 at pages 18 to 23, describes the train control system for the San Francisco Bay Area Rapid Transit District of the United States. Other articles relating to the same train control system were published in the IEEE Transactions On Communication Technology for June 1968 at pages 369 to 374, in Railway Signaling and Communications for July 1969 at pages 27 to 38, in the Westinghouse Engineer for March 1970 at pages 51 to 54, in the Westinghouse EngineerforJuly 1972 at pages 98 to 103, and in the Westinghouse Engineer for September 1972 at pages 145 to 151.A general description of the train control system to be provided for the East-West line of the Sao Paulo Brazil Metro is provided in an article published in IAS 1977 Annual ofthe IEEE Industry Applications Society at pages 1105 to 1109.

It is known to use microprocessors in passenger vehicle control, and a general description of the microprocessors and the related peripheral devices which can be used with this invention is provided in the Intel 8080 Microcomputer Systems Users Manual currently available from Intel Corp., Santa Clara, California 95051.

This invention in its broad form resides in apparatus for controlling a train of vehicles using a determined desired velocity of a train of vehicles in response to one of a reference velocity signal, which is established by an input command velocity signal that can be modified by a cut out car condition or a performance restricted condition, and a program stop velocity signal, the apparatus comprising means for providing a velocity control signal for said train in response to the lowest of said reference velocity signal and said program stop velocity signal, means for providing a start-up enable signal to permit the train to move in response to said velocity control signal requesting greater than a first predetermined velocity and in response to the actual velocity of the train being less than a second predetermined velocity, and means for providing an effort request signal for controlling the actual velocity of the vehicle by comparing the desired velocity signal with the actual velocity signal.

In a preferred embodiment, an improved passenger vehicle speed control apparatus and method are provided including hardware and software to control the speed of a train vehicle by means of an acceleration request or P signal, as based on the maximum speed allowed established by received speed code, the cutout car condition, performance level, and the program stop information from the program stop routine. This is done by selecting the desired speed for the vehicle to go and then comparing that against the actual vehicle speed from the tachometer information and thereby determining the P signal request. The desired speed is either the action velocity or the program stop velocity.The look ahead velocity is compared against the action velocity and when the look ahead velocity becomes less than the action velocity plus an offset, the desired speed is the program stop velocity, otherwise the desired speed is the action velocity. The offset is a function of the P signal request at that present time which is an indication of whether or not the vehicle is accelerating, decelerating towards that action velocity or just speed maintaining at that action velocity.

In a second embodiment, an improved passenger vehicle operation speed control apparatus and method are provided for determining the vehicle velocity in accordance with a provided desired or reference velocity signal in relation to a received speed command code from the track circuit signal block as modified by certain additional considerations such as a cutout car, performance reduction and a program stop operation. In addition, a start-up enable output is provided to permit the vehicle to start to move even though the tachometer output is zero.

The invention will be further explained in the following description of a preferred embodiment, described by way of example and to be studied in conjunction with the accompanying drawing in which: Figure lisa schematic showing of the passenger vehicle velocity control system operative in accordance with a preferred embodiment of the present invention; Figure 2 illustrates the microprocessor control apparatus provided for the control of a passenger train vehicle including the present speed maintaining operation; Figures 3A, 3B, 3Cand3D illustrates the flow charts of the provided program routines in accordance with the preferred embodiment of the present invention; Figure 4 is a memory storage table showing the address locations of the variables stored in RAM; and Figure 5 is a functional illustration of the here provided Pl controller apparatus.

Figure 6 is a schematic showing of the passenger vehicle system operative with the present control apparatus; Figure 7 illustrates the microprocessor control apparatus including the control programs for a passenger vehicle train in accordance with the present invention; Figure 8 illustrates schematically the vehicle desired velocity system of the present invention in relation to the other provided control programs for a passenger vehicle; Figures 9A, 9B and 9C show the data flow of the program provided for the vehicle desired velocity system of Figure 8; and Figure 10 shows the time gate for start-up provided in relation to the overspeed, balance and tachometer integrity checking apparatus of the present invention.

As shown in Figure 1 the central control computer system 100 communicates with the station ATO and ATP equipment 102 to establish the proper vehicle routes and to set up desired speed profiles for the track circuits by sending this information to the wayside boxes 104. This puts the speed code information on the track circuits 106 in the form of command speed codes. These speed codes are received by the vehicle antennas and preamplifiers for the antennas 108 and go into the speed decoding module 110 which takes the FSK serial speed codes and converts them into serial logic level data as indicated to the right and the left of the speed decoding module 110. This information goes into the two microprocessors CPU 1 and CPU 2 for each individual train as the train is progressing down the track.In particular, the inputioutput modules 112 is operative with CPU No. 2 and CPU 2 has stored within its memory a decoded maximum allowable speed.

Also within the memory of CPU 2 is an indication of the last received performance modification from the ID system. The Pl controller speed maintaining program 114 performs the vehicle speed maintaining function and generates a P-signal and a brake signal. The characteristics of the brake signal are such that if it is a logic 1 which is defined as 100 milliamps, this permits the train vehicle to be in power and if it is a logic zero, which is defined as 0 milliamps, the train vehicle is in brake. The P signal is such that 60 milliamps is its mid-scale range and the train vehicle wants to essentially coast with a 60 milliamp P signal; from 60 up to 100 milliamps is the normal power range and from 60 down to 20 milliamps is the normal brake range.A 'P' signal of 20 milliamps would call for full service brakes and a P signal of 100 milliamps would call for maximum acceleration. The P signal 116 and the brake signal 118 are shown coming out ofthe CPU modules 112 since the CPU and I/O modules are the actual hardware that is where the signals originate, whereas the program 114 is the software contained within the CPU 2. In the hardware, there is an analog signal out of the I/O module of CPU 2 which goes to a P signal generator module that converts that analog signal having a value from -2 to -10 volts into a 20 to 100 milliamp P signal and then there is a logic level coming out of CPU 2 I/O module which goes over to a P and brake signal generator module to turn the brake signal generator on or off as required to generate the 100 milliamps or 0 milliamps.The P signal and the brake signal are put on train lines and go to each car vehicle for a multiple car vehicle train. The only CPU 2 doing this speed maintaining function is in the head end car. However, the P and brake signals go to the propulsion and brake equipment 120 on each car. The propulsion brake control equipment 120 then converts these signals into motor current request and brake pressure request. The vehicle motors and brakes 122 control the actual train velocity. The train velocity is sensed by tachometers 124 physically mounted on the motor axles, and the tachometer signals then come back into the CPU 2 as a speed feedback.The function of the speed maintaining program 114 is to first determine what desired speed of the vehicle should be and then try to control the vehicle speed through the P signal and the brake signal such that the tachometer feedback agrees with that desired speed.

In Figure 2 there is shown in more detail the speed maintaining Pl Controller System, including hardware and software, in relation to a train vehicle speed control system. The vehicle antennas 140 provide speed code and control signals, such as the cutout car signals. The speed code information is supplied to the speed decoding system 142, and also the program stop related information is supplied to the program stop subsystem 144. The speed decoding system 142 provides the maximum allowable speed modified for the cutout cars, and this goes to the vehicle desired velocity system 146.The actual desired velocity input 148 into the speed maintaining controller system 150 is a combination of the reference velocity input 152 from the speed decoding system 142 and the PM number 154 to provide an action velocity variable 156 which is stored in the CPU and is generated by the speed decoding system 142. The program stop velocity 158, the look ahead velocity 160 and the action velocity 156 are utilized to determine the velocity 148. The action velocity is the maximum speed modified by cutout cars and modified by the PM speed requirements. There is also a PM acceleration limit such that the decoded PM code results in a limit to one-half acceleration which is a direct input into the speed maintaining controller system 150. The desired velocity 148 uses this PM acceleration limit information or program stop velocity information, whichever is more restrictive.Also, the action velocity is modified by subtracking either 2 or 4 KPH, with the action velocity being an absolute maximum for controlling the vehicle speed below the action velocity, but not too far below it, or the vehicle station to station run times will be increased.

After the desired velocity 148 is established and whether the vehicle is allowed full acceleration or half acceleration, the Pl controller system 150 then operates a software Pl controller to generate the P signal 116 and the brake signal 118, which go to the propulsion and brake equipment 120. The propulsion and brake equipment 120 controls the motor vehicle 122, including the vehicle motor and brake. The vehicle is coupled to the tachometers 124. In reality 4 tachometers are provided, with tachometer 4a being used for the speed feedback, although any one of them could be used to provide this speed feedback signal. For the actual speed maintaining controller system 150, only one tachometer 4a is used, and the actual speed signal gets fed back to the car carried ATO equipment 162.

The desired velocity 148 that the P controller system 150 is trying to maintain is a function of the mode that the vehicle is in; in other words a dual aiming point is present depending upon whether the vehicle was in power or in brake. An objective of the Pl controller system 150 operation is to cut down on the number of power and brake mode change transitions.

The program routine shown in Figure 3A has at this time available as information inside the computer the action velocity 156 which is determined by the received speed codes modified by the cutout car information and further modified by PM level, a program stop velocity 158, and a program stop look ahead velocity 160, which is the velocity the program stop program thinks the vehicle should be going at approximately one second in the future. In addition, there is an indication whether or not the performance modification wants the limit of one-half acceleration, and there is the actual speed that the train vehicle is moving at present. The Pl controller system 150 will generate a P signal level, which will be between 20 and 100 milliamps, and a brake signal whjich is going to be a 1 or a 0.The brake signal is just a logic signal to make sure that all the cars in the train are in the same mode. Other auxiliary information provided to the speed maintaining program includes a non-vital roll back indication from tachometers 4a and 4b to verify that the vehicle is going in the proper direction. The program shown in Figure 3A starts at block 300. In block 302 a check is made to see if the vehicle is moving in the right direction, i.e. if a roll back indication is present. At block 304 the P signal is set to a value of 20 milliamps. At block 306 the P signal is passed through a jerk limiter to limit its rate of change and the PSIGI is the input to the jerk limiter and PSIG is the output of the jerk limiter such that the output will get to 20 milliamps at its jerk limited rate. At block 308 of the program stop flags are cleared.At block 310 the integral portion of the Pl controller is reset to zero to keep it within the desired range of control. At block 312 the brake mode is set, since the request is for 20 milliamps of P signal and the only way to get into the brake mode is forthe brake signal to be low. If there was no roll back at block 302 then at block 314 a check is made to see whether or not the vehicle is in an underspeed condition.The speed maintaining program is operating underneath the overspeed umbrella such that if at step 314 the vehicle is detected to be going faster than the maximum allowable speed based on the speed code information now being received from the track circuit, the P signal generator will be turned off and this speed maintaining program will lose control since the P signal, no matter what this program does with the P signal, is set to zero because the overspeed system has turned it off, and the overspeed system is requesting full service brakes.

If block 314 detects that the overspeed condition exists, at block 316 the P signal is set in midrange and the program goes again to blocks 306, 308,310 and 312 where the P signal is set to the temporary value of 60 milliamps, any program stop flags are cleared, the integral controller is reset, the brake mode is set and the P signal will jerk limit to 60 milliamps.

The reason for picking the 60 milliamps value at block 316 instead of again setting the P signal to 20 milliamps at block 304, is to avoid trouble coming out of overspeed. If the vehicle is going at some high speed and then gets a lower speed code, the vehicle is controlled to slow down to this lower speed code. At the point where the vehicle just goes below this overspeed value, the overspeed system permits the speed maintaining system 150 to control the vehicle and maintain the vehicle speed at a little below the overspeed limit. The prior art analog Pl controller that was used in the past at this time had its output at 20 milliamps, and it did not start taking the brakes off immediately when the vehicle came out of overspeed.With the present control operation provided by step 318, when the vehicle comes out of overspeed the P signal is at 60 milliamps which immediately gets the brakes off because there is not much time available to try to lock onto this new desired speed code. To avoid this slow response of the brakes, when the vehicle first comes out of overspeed the control should ask for no brakes and then let the speed maintaining system 150 control the vehicle speed from there. At block 314 when the vehicle is detected to be in an underspeed condition, at block 318 a check is made to see if the vehicle is at 0 speed. If the vehicle is at 0 speed, at block 320 a check is made to see if the vehicle is ready to start moving; in other words if the start-uptime gate and the logic which operates with the start-up time gate is saying 'go'.If the vehicle is stopped and should start moving, the start-up time gate provides a short duration signal to bypass and overcome the fact that there is no tachometer integrity detection. The vehicle is sitting at 0 speed, and to start it moving, it is necessary to bypass the tachometer integrity check to get the vehicle started. The speed maintaining program at step 320 looks at that situation to determine if the vehicle should start moving or should not start moving and it checks the start-up time gate at block 320. If the start-up is disabled, then again the P signal is set to 60 milliamps at step 322.Now when the start-up time gate output signal is found at block 320 and the vehicle should start moving, the speed maintaining program is then starting from a P signal of 60 milliamps and starts ramping from there essentially to avoid having to wait for the jerk limited time to get the brakes off since there is no actual jerk of the vehicle in going from full brake to no brake when the vehicle is already stopped, and this enables the vehicle to get started a little faster. At block 324 a check is made to see if a 0 speed command is received from the track circuit. If a zero speed command is sensed at block 324, the program goes through blocks 304 to 312 to set the P signal to 20 milliamps because the vehicle is getting a 0 speed command.If the vehicle is not receiving a zero speed command then at block 326 a check is made to determine whether or not the speed control is in program stop already, with the program stop flag PSFGI set equal to 1. If the speed control at step 326 is found to be already in program stop, then at block 328 a check is made to see if the reference velocity called REF, which is the desired velocity, is equal to the program stop velocity. If the speed control is not in program stop, then at block 330, in an effort to determine how close the vehicle speed is to the program stop velocity profile, an offset is added to the vehicle actual speed for comparison with the look ahead velocity. If the vehicle is now positioned between stations, both the program stop velocity and the look ahead velocity are set a value above the highest command speed code the vehicle will receive. If the vehicle is not actually in a program stop operation, then these checks will show that the vehicle is not in a program stop. At block 332 a check is made to see if the tach plus the added offset value temp is less than the look ahead velocity; and if not, then the vehicle is going at normal speed and is not in program stop, and the program goes to the label BGN1. However, if a program stop is found at step 332, then at block 334 the reference is set again to the program stop velocity, since this is the velocity the vehicle should follow.At block 336 the program stop flag PSFG 1 is set equal to FF hex which is true, such that the next time the program comes through block 326 it will come out of the yes statement. Blocks 326 and 330 to 336 are provided to detect that the vehicle is in program stop, and once the program detects that the vehicle should be in program stop then the program just comes through blocks 326 and 328, since the vehicle is approaching or is on the program stop profile.

Block 338 is provided to check if for some reason the train is going too slow. Since the vehicle is in program stop mode and in the brake mode, the P signal will never go above 60 milliamps and the brake signal will never go to a logic 1, so if for some reason, such as the vehicle is going up a hill or there is a tremendous amount of drag on the vehicle, causing the vehicle to go too slow, it is desired for the speed control to come back out of the program stop mode, at block 338, to get back onto the normal speed maintaining mode, a check is made to see if the vehicle speed is 10 KPH below the program stop velocity, in other words, is the actual speed plus 10 KPH below this VELPS, which is the program stop profile velocity, and if so, the program goes to the BGN1 label which leads to normal speed maintaining and out of program stop.This check at step 338 normally would not provide a No output, but it could in theory, do so due to some abnormal vehicle situation so this option is included. Normally the program will come to block 340, where a check is made of the cutout car status; for program stop there is either a cutout car or there is not a cutout car. If the cutout car information indicates a cutout car switch is set by the operator, at step 342 a cutout car flag is set which is used later in the program, or the flag is cleared at step 344. Depending upon whether the cutout car flag is cleared or it is not cleared, the program now starts a flare out to help get the brakes off and follow the desired decreasing vehicle deceleration at the end of this program stop profile, and this is started at two different speeds, depending upon whether the vehicle is not or is in cutout car.Block 346 determines whether the cutout car flag is cleared, and if it is cleared, then block 348 checks to see if the program stop speed is equal to or less than 8 KPH. If the cutout flag is not cleared, then at block 350 a check is made to see if the program stop velocity is equal to or less than 4-1/2 KPH. If the program stop velocity is above both of these speeds, the program comes out the No end of block 350 up to block 352 where a check is made to see if the program stop flag PSFLG is set. If it is set at step 352, that indicates that the program has been through this path before, so it goes to the control portion of the program. If the program has not been through this path before, the program stop constants will have to be set. The Pl controller requires three constants for its intended operation.There is a K1 constant which is the proportional gain constant, K2 which is the integral gain constant and K3 which is an offset or lead term. The first time through the program stop, these values are set to constants which can be unique to program stop and to change the characteristics of the P controller system so that they more closely follow the program stop profile. It turns out in actual practice that in relation to the constants K1 and K2, no matter what mode the speed control is in, they are set the same. Blocks 354 and 356 set K1 and K2. At block 358 K3 temp is set to a value plus something which is proportional to the actual speed the vehicle is going. At block 360 the check is made to see whether or not the cutout car flag is set and whether or not the vehicle is in cutout car.K3 is set to this K3 temp at block 362 or it is set to half of K3 temp at block 364. These results were obtained experimentally and gave the best and smoothest following of the program stop profile. The constant K3 only gets used in program stop as a lead term since the speed control is trying to follow a ramp. Any other time when is is desired to maintaining a constant velocity, the lead term is not needed. Since the program only goes through this path including steps 354 to 364 the first time the program detects that it should go into the program stop, the integrator should be at a known value so again a momentary reset at block 366 is provided to reset the integrator to zero. The integrator now is in the controller, but this just initializes the integrator to a known value.The program stop flag PSFLG is set in block 368 to FF and the next time the program comes through the block 352 it goes immediately to the control section and skips presetting all these constants again.

Now is the vehicle gets below the speed where the program stop starts flaring out, which is coming out of the blocks 348 or 350, the program goes to block 370 to check the cutout car status and set a temporary register at block 372 or 374 to a value of 1 or 2. Since the vehicle deceleration in this area is going to be decreasing, the program starts pulling this K3 offset back towards 0, and this is done depending on the vehicle speed at two different rates and this is the reason for blocks 372 and 374. At block 376 K3 temp is set equal to K3 temp minus temp, for decreasing the K3 constant and then at block 378 the cutout car flag setting~ is checked such that based on the cutout car status the offset constant K3 is set to equal either K3 temp at block 380 or one-half of K3 temp at block 382. This decreases K3 temp by different amounts depending upon the cutout car status in block 370. In block 384, the proportional gain constant for the controller is changed.

At block 386 the integral constant is left at the same value. By experimental testing both the proportional and integral gains were changed, but it was determined that the integral gain really did not have to be changed at this time although provision was made for changing the integral gain during this flare out if desired. The program now goes to the control section.

If the vehicle is not in program stop either at block 332 or 338 a no answer will take the program to block 390 and this is the normal maintaining portion of the program. Since the vehicle is not in program stop, the program stop flags PSFLG and PSFGI are both set equal to zero. At block 392 a comparison is made of the tach against the action velocity minus two. The action velocity is what the vehicle is going to be working with because the vehicle speed is definitely below the program stop profile and the vehicle is between stations and not in program stop. If the tach is greater such that the vehicle actual speed is greater than the action velocity maximum speed point minus 2 KPH, in other words the vehicle is higher in speed than 2 KPH below the action velocity so the vehicle should be in brake. At block 394 the reference velocity is set equal to the action velocity minus 2.At block 396 the brake mode is set and at blocks 398, 399 and 400 the K1, K2, K3 constants are set. At block 392 if the vehicle speed is not greater than the action velocity minus 2, at block 402 a check is made to see if the vehicle speed is less than 4 KPH below the action velocity to determine if the vehicle should be in the power mode. This illustrates the provided dead band, since the brake maintaining point is 2 KPH below the action velocity and the power maintaining point is 4 KPH below, so the vehicle speed can essentially drift between these two with no change in modes. It is only when the vehicle speed gets higher than 2 KPH below or lower than 4 KPH below that a mode change occurs.If the vehicle speed is more than 4 KPH below the action velocity, at block 404 the reference velocity is set equal to the action velocity minus 4 KPH, at block 406 the power mode is set, and blocks 408,410 and 412 set the constants K1, K2 and K3 the same as blocks 398,399 and 400 to have the same constants and the same system gains for power or brake. A provision is made to provide different constants in the brake mode as compared to the power mode. If the vehicle speed is in this deadband because it is below the higher speed at block 392 and above the lower speed at block 402, then at block 414 a check is made to see if the vehicle is in power. If the answer is yes, at block 416 the reference is set equal to the action velocity minus 4, because the vehicle should stay in power and that is the reference velocity for the power mode.If the vehicle is not in power at block 414, then ir must be in brake, so at block 418 the reference velocity is set equal to the action velocity minus 2, because it should stay in brake and no mode setting is done because the mode is still set from where it was before. The program now goes to Figure 3B of the speed maintaining program.

Since the program shown in Figure 3B is working with unsigned numbers, the absolute value of speed error is calculated and then a flag is set to indicate whether it is overspeed or underspeed. At block 440 a check is made to see if actual speed is greater or equal to the reference velocity. If it is not and the vehicle is going slower than the reference velocity, at block 442 an underspeed flag is set, and at block 444 the speed error prime is set equal to the reference minus the tach. At block 440 if the vehicle speed is equal to or above the reference speed, then at block 446 the underspeed flag is set equal to zero and at block 448 the speed error prime SE' is set equal to the tach minus the reference, which again is the larger number minus the smaller number.It could be the tach is equal to the reference speed, in which case at block 448 this would be the equal minus the equal and the result is zero. At block 450 a check is made to see if this speed error prime is greater than 15, and if so at block 452 it is held to 15; in other words this is the dynamic range on the input where 15 is 7-1/2 KPH plus or minus. If the speed error prime is greater than 15 in block 452, it is set to 15 and if it is not greater than 15 it is left at whatever it is.At block 454 the proportional gain called PP is set equal to 0.Kl times 16 times the speed error, where 16 is just a scale factor to increase the resolution, and 0.Kl is used because the multiplication is an eight bit number times an eight bit number where what is desired is an eight bit result so that the K1 eight bit number is considered as a fractional portion; in other words it is whatever the number is, divided by 256, times the other number, and the result will be an eight bit number. The maximum value of K1 is effectively 1, and the block 454 multiplies by less than unity gain.The scaling on the ultimate P signal output is 102 which is 40 milliamps, and the control is working from a 60 milliamps point going 40 milliamps higher or 40 milliamps lower, so to provide a limit within that range, at block 456 a check is made to see if the PP term is greater than 102 which is the maximum limit. The range in either power or brake is 40 milliamps, and at block 456 a check is made to see if the PP term is greater than 40 milliamps, and if it is then at block 458 it is set to what corresponds to 40 milliamps and if it isn't then the PP term is left at whatever it is.At block 460 in relation to numerical integration, the delta integral term Pl1, in other words, that which is changed since the last time, is set equal to 0.K2 times the speed prime, which provides the change in the integral term since the last time through this program at 18 times a second. At block 462, if the underspeed flag is equal to zero, then the program goes to overspeed and if it not equal to zero the program goes to UNSP. Taking the underspeed case out of block 462, at block 464, since it is desired to simulate the Pl controller, which is proportional to the ratio of the two capacitor values and the integral portion is 'proportional to R1 and C2.The advantage of doing the controller this way is any time the output of the amplifier of this Pl controller is in saturation, the integral portion is essentially reset and the integral portion always has a maximum value of the difference between what the output is and the saturation limit. This keeps the integral oportion of the controller within bounds, so at block 464 PIMAX is set to full scale 102 minus whatever the proportional part is; if it were far enough out that the proportional part is full scale, then PIMAX is zero. At block 466 the integral portion is set to the past value plus the change which is Pl plus Pl1 and this is digital integration.At block 468 a check is made to see if Pl is positive, and if it is positive, at block 470 a check is made to see if it is greater than Pl max. At block 472 if Pl is greater than Pl max, then Pl is set to Pl max. If Pl is not positive at block 468 or less than Pl max at block 470, then Pl is left at whatever it was. At block 474 PSIG1 is set equal to 153, which is the midpoint corresponding to 60 milliamps, plus the proportional portion PP plus the integral portions Pl minus K3 which is the lead term. The only time the lead term K3 is used is in the brake mode, which means K3 even if it is a positive value wants to get treated like a negative value going towards a lower P signal value so it is always subtracted, and its sign is not carried through.

If at block 462 the vehicle is going too fast and is above the reference speed, then at block 476 Pl max is set equal to 102 minus the proportional portion PP, and since the vehicle is overspeed and now working in this region from 60 milliamps down to 20 milliamps, the K3 lead term is substracted. For the typical speed maintaining K3 is at zero, but in program stop K3 has some value. At block 476 PP is subtracted which can be up to a value of 102 and K3 is subtracted which can result in a non-zero value, so P max at block 476 could go below zero and go negative in which case it should be made zero; again the program is now working with signed numbers, but is handling the signs as either an addition or substraction based on underspeed or overspeed.The minimum value of Pl max should be zero, so at block 478 a check is made to see if it went below that, and if it did, at block 480 it is set to zero; otherwise PIMAX is left at what is was. At block 482, since the vehicle is going too fast, the integral portion is essentially going less positive and more negative so it is desired to subtract this delta amount of Pli from whatever the past value was, so PI is set equal to Pl minus Pl1. At block 484 a check is made to see if Pl is negative. If it is, at block 486 a check is made to see if the absolute value of Pl is greater than Pl max.If Pl is negative, it is desired to see if the value of Pl is less than the maximum value Pl max. If is isn't, then at block 488 Pl is set equal to minus Pl max. If Pl is not negative at block 484, or the magnitude is less than its allowed magnitude at block 486, the program skips to block 488.

At block 490, PSIG1 is generated as the 153, or 60 milliamps, midpoint, minus K3 plus Pl and minus PP. Pl is added because it can be a negative number, so it takes care of its own sign. The proportional part PP, since the vehicle is in overspeed, is a positive magnitude, but it should be subtracted from the P signal. So block 490 calculates PSIG I. At block 490, since the program subtracts PP and K3, the P signal 1 can actually go below the minimum value which is 51, so at block 492 a check is made to see if it is less than the equivalent of 20 milliamps, and if it is, at block 494 it is held to 20 milliamps. Either one of the underspeed or the overspeed path goes to block 496, where a check is made to see if the P signal PSFG1 is not equal to zero.If the vehicle is in program stop, then it would be nice to be able to get the vehicle back into the power mode if it is going too slow. At block 498 a check is made to see if PSIG1 is greater than 63 milliamps, and if it is then at block 500 the power mode is set. At block 498, if PSIG1 is not greater than 63 milliamps, then at block 502 a check is made to see if it is less than 147 which represents 57 milliamps. If PSIG 1 is not less than 147, this program is done, and if it is, then at block 504 the brake mode is set, so this is doing hysteresis on the P signal to determine brake or power mode if the vehicle is in program stop. At block 496, if the vehicle is not in program stop, at block 506 a check is made to see if it is in power mode.If the vehicle is in power, at block 508 a check is made to see if the P signal is less than 153 or 60 milliamps; the vehicle is in power mode and the P signal should be less than 60 milliamps. If not, it is held to 60 milliamps at block 510, and since the only thing that can take the P signal to less than 60 milliamps is the integral portion PI, it is reset to zero at block 512. Then at block 514 a check is made to see if PMACC is set, and that is the indication that a limit of half the acceleration is desired. If that is set at block 516, a check is made to see if the P signal is greater than 220 corresponding to 82 milliamps, which is one-half acceleration.At block 518 the integral controller Pl is checked to see if it is equal to or greater than +1; the integral portion Pl of the controller is the reason for the higher P signals If it is, at block 520 1 is subtracted from PI. If the P signal is above 82 milliamps at block 516, at block 522 it is limited to 82 milliamps. At block 506, if the vehicle is not in power, it is in brake. At block 524 a check is made to see if the P signal is above 60 milliamps, and it is at block 526 that the integral portion Pl of the controller is set to zero, and at block 528 the P signal is limited to 60 milliamps. The program now goes to the jerk limit program which jerk limits the P signal.

At block 540 a check is made to see if the P signal is less than P signal 1, and if it is, at block 542 the difference is established. At block 544, if that difference is greater than 6, it is limited to 6 at block 546. At block 548 the P signal is set equal to the P signal minus that limited difference temp. Back to block 540, if the P signal is not less than P signal 1, then at block 550 the program again finds the difference between the two values. At block 552 if this difference temp is greater than 6, it is limited to 6 at block 554. At block 556 the P signal is set equal to the P signal minus the difference temp, and the functions such that the P signal will go towards the P signal 1 at the maximum rate of 6 units for each pass through the program every 18th of a second, and 6 times 18 is 108, so the jerk limiter permits a change of 108 units in one second.Since 102 is a full scale range for the Psignal, it can go from essentially 60 milliampsto 100 milliamps, or from 60 milliamps to 20 milliamps in just slightly less than 1 second, and a one second limiting rate is desired. At block 558 the P signal is output. At block 560 the output mode is used to turn the brake signal on or off.

The tables in Figure 4 show the RAM variables K1, K2 and K3 which are the gain constants set by the program. The P signal 1 in location 053 is the unjerk limited P signal request. Pl is the integrator results; it is the output of the integrator, and it is a double byte. The integral component Pil of the controller is the change every 18th of a second, and it is again a double byte variable. These are double bytes since the program is working with such small units on a per cycle basis, if only an eight bit resolution were provided this delta PI might always be zero and could be lost as a result of rounding error. The following table is provided to define the various labels shown in Figure 4 of the drawings.

LABEL: DEFINITION: K1 Proportional Gain Constant K2 Integral Gain Constant K3 Offset Constant PSIG1 P-Signal before Jerk Limiting Pl Integrator Result Pl1 Change in Integrator Result per 1/18 second = K2* {tach - rebl UNDER Flag, = FF when tach < command, = 0 when tach > command PP Proportional Result= K1* 16* tach-comml PIMAX Maximum Value for Integer Portion of PI such that PI + PP never exceeds full scale (+ 40 ma) PSFLG Flag Set first time thru Prog Stop Routine, 0 = was not in Prog Stop FF = was in Prog Stop SPDER Speed Error (Comm -Act) used for monitoring only K3 TMP Temporary Storage for K3 PSFG1 Flag to indicate in Prog Stop 0 = not in Prog Stop 1 = In Prog Stop OUT61 Output Port 61 Storage BRK-SIG Generator Control Bit, 0 = On = In power.

1 = Off= In brake VELAC Action Velocity = Lessor of Speed Code or PM Speed 2 bits/KPF VELPS Program Stop Velocity = functibn of distance to go 2 bits/KPF VELLA Prog Stop look ahead velocity = VELPS one second from now 2 bits/KPF PSIG P-signal - after Jerk Limiter (102 bits = 40 ma) PMACC 1 = 1/2 acceleration max, 0 - full acceleration allowed IN73 Data from input port 73

COC 86 # Either bit = 0 means follow reduced acceleration COC 71 Prog Stop Profile ACTSP (Tach) Actual Train Velocity 2 bits/KPH REF Reference Velocity = VELPS Ib in Program Stop = VELAC - 4 KPH Lob in Power = VELAC 2 KPH Lob in Brake The purpose of the speed maintaining program is to control the train velocity through a train acceleration request, and this acceleration request is based on the received speed code, the train vehicle actual speed and the program stop desired velocity.The program takes this speed code velocity or the program stop velocity, whichever is lower, and looks at how they are converging. If they are converging, the program combines this with the vehicle actual speed tachometer information to come up with an acceleration control for the vehicle such that the vehicle will follow the more restrictive of these speeds In the prior art an acceleration request was generated from the speed code and the tach and also from the program stop velocity and the tach and; whichever was asking for less acceleration or more deceleration, that would be the one that would control the speed of the train, such that essentially two separate closed loop velocity control systems were provided and the problem was to stabilize two separate control loops.

The present speed maintaining control apparatus requires only one controller and the restrictive speed selection is provided ahead of that controller. Since the speed code velocity is typically not changing and the program stop velocity is changing, it is not desired that the vehicle should make a sudden change in acceleration to follow this changing signal, so the look ahead velocity is used to determine when it is time to go in the program stop operation and follow the program stop velocity, so the transition is based on the time and the difference between the program stop velocity and the amount of the P signal that is presently being requested which is an indication of the present actual acceleration.This permits the vehicle to start going into brake a little bit sooner than might be obvious from just looking at the exact program stop velocity to get the proper acceleration or deceleration for the train to approximately follow the program stop velocity and not end up overshooting. Before the vehicle approaches a station both the program stop velocity and the look ahead velocity are large numbers. When the vehicle senses the program stop tape the latter two velocities become some numbers which are larger than the present speed maintaining velocity, and then these two numbers in the program stop will start decreasing as the vehicle continues into the station.The look ahead velocity is compared against the speed that the vehicle is going plus the offset term which is a function of the amount of P signal requested to allow the vehicle to be accelerating towards the program stop curve and to be in program stop sooner than if maintaining constant speed because it would take longer to jerk limit out of this acceleration into the program stop braking rate. Ideally, it is desired to hit the program stop velocity at the program stop nominal deceleration rate which is 0.85 meters per second. The look ahead velocity and the P signal are used to determine when the vehicle will go into program stop, and the K3 lead term in software is set to the nominal P signal acceleration or deceleration so the train signal will start going towards the deceleration rate and hopefully when it reaches that deceleration rate it will be on the program stop curve.The P signal offset causes the train vehicle to start decelerating, and then instead of using the reference velocity with the tachometer for speed maintaining, the program stop velocity versus the tachometer is used to generate the P signal, plus the P signal is forced toward brake at this time. It turns out that when this is done the program stop velocity is still above the vehicle actual velocity so the train wants to speed up, however this offset is saying for the train to slow down, and there is an open ioop operation where the vehicle wants to be slowing down, but yet the speed error is requesting a speed-up, and the two signals sort of oppose each other, and by the time the P signal goes into brake then starts coming off in a jerk limited manner, the vehicle is on the program stop curve.This allows the vehicle to hit the program stop curve tangentially, even though it might have been accelerating before going into the program stop. The look ahead velocity is treated as if it is just a parallel but lower velocity curve to the program stop velocity. When the vehicle is on the program stop curve and now the controller is looking at the difference between the program stop velocity and the actual velocity to contrpl the P signal, there is still the offset in the P signal. To allow the train vehicle to follow the flare-out at the end of a program stop, at a particular speed approximately where the program stop table starts its flare-out, the offset starts to be removed. This allows the train to follow the flare-out of the program stop curve.Since the theoretical acceleration of the program stop table is increasing, becoming less negative down at the low speeds, the P signal should start asking for less brakes at the lower speed.

The speed maintaining is set up so that a 2 KPH deadband is provided. As long as the vehicle is 4 KPH below the commanded speed, it will stay in power until it gets to 2 KPH below the commanded speed, and then it will go into brake and stay in brake until it gets back to 4 KPH below the speed command. If the vehicle is in program stop, the power brake change over is purely determined by how much P signal is requested; if it is for more than 63 milliamps, the vehicle goes into power, and if it is for less than 57 milliamps the vehicle goes into brake.

In Figure 5 there is functionally shown an emulation of the PI controller system of the present invention.

The proportional gain relationship is as follows: C1 K1 2 bits 40 ma = 16 * * + in inma/AKPH C2 256 KPH 102 bits The normal operational limitsforthe proportional gain are: malZLKPH Brake 6.27 Power 6.27 Program Stop 7.84 Program Stop Final 9.41 The integral time constant relationship is as follows: 1 K2 26.71 40 ma 18times = * * ±--- * in ma/AKPH sec.

RIC2 256 KPH 102 bits sec.

The normal operational limits for the integral time constant are: malAKPHlsec.

Brake 0.88 Power 0.88 Program Stop 0.44 Program Stop Final 0.44 These gain relationships can easily be changed for a system where speed is denoted in miles per hour.

As shown in Figure 6, the central control system 100, which is usually located in a headquarters building or the like, receives information about the transit system and individual vehicle train operation to apply desired performance adjustments to the individual vehicle trains. The central control system supervises the schedules, spacing and routing of the trains. The passenger loading and unloading stations 112, 114 and so forth are provided to operate with the central control 100 as desired for any particular transit system. The wayside equipment 116, including track circuits and antennae, is located along the vehicle track between the stations and is provided to convey information in relation to the passenger vehicles passing along the track.

Afirsttrain 118 is shown including four vehicle cars in the arrangement of an A type car at each end of the train with intermediate B type cars. A second train 119 is shown including two vehicle cars, with one being an A type car including computer control apparatus and one being a B type car which includes no computer control apparatus for controlling the train vehicle. The train control apparatus 120 carried by the front Atype car 121 of the first train 118 is shown in greater detail in the phantom showing 120' of the front car 121.

Similarly, the train control apparatus 122 carried by the rear A type car 123 is shown in greater detail in the phantom showing 122' of the rear car 123. The train control modules 124 in the train control apparatus 120' includes the program stop receiver module, the speed code receiver module, the vital interlock board, power supplies and all the modules required to interface with the other equipment carried by the train vehicle 121.

Information is sent in relation to the input/output modules 125, and the microprocessor computers 126, 127 and 128. There is a direct communication link through the input/output modules 125 between the CPU1 computer 126 and the CPU2 computer 127. There is a direct communication link from the CPU1 computer 126 to the multiplex train line MTL CPU computer 128. A similar train control apparatus 122 is provided for the rear car 123. The front car 121 and the rear car 123 are connected together through well-known train lines, which may go through the couplers and the individual train vehicles.

The multiplex train line connected between the front multiplex CPU and the rear multiplex CPU is one pair of lines in the train line.

As shown in Figure 7 the central control computer system 200 communicates with the station ATO and ATP equipment 202 to establish the proper vehicle routes and to set up desired speed profiles for the track circuits by sending this information to the wayside boxes 204. This puts the comma-free binary speed code information on the track circuits 206 in the form of speed command codes. These speed command codes are received by the vehicle antennas and preampiifiers for the antennas 208 and go into the speed decoding module 210 which takes the FSK serial speed codes and converts them into serial logic level data as indicated below the speed decoding module 210.This information goes into the two microprocessors CPU1 and CPU2 for each individual train head vehicle as the train is progressing down the track In particular, the input/output modules 212 operative with CPU No. 2, and CPU 2 has stored within its memory a decoded maximum allowable speed. Also within the memory of CPU2 is an indication of the last received PM performance modification from the ID system. The speed control and start-up conditions program 214 within the computer CPU2 of the train vehicle receives the cutout car modified reference velocity from the CPU2 speed decoding and error routine 304, the program stop velocity from the program stop program 218 and calculates the PM performance modification velocity. The output signals from the speed control program 214 are shown in Figure 8.The Pl controller speed maintaining program 220 performs the vehicle speed maintaining function and generates a power or P signal and a brake signal. The characteristics of the brake signal are such that if it is a logic 1 which is defined as 100 milliamps, this permits the train vehicle to be in power and if it is a logic zero, which is defined as 0 milliamps, the train vehicle in in brake mode. The P signal is such that 60 milliamps is its mid-scale range and the train vehicle want to essentially coast with a 60 milliamps P signal; from 60 up to 100 milliamps is the normal power range and from 60 down to 20 milliamps is the normal brake range. A P signal of 20 milliamps would call for full service brakes and a P signal of 100 milliamps would call for maximum acceleration.The P signal 116 and the brake signal 118 are shown coming out of the CPU modules 212 since the computers CPU1 and CPU2 and the associated l/O modules are the actual hardware involved and that is where the signals originate, whereas the program 214 is a software program contained within the CPU2. In the hardware, there is an analog signal out of the I/O module CPU2 which goes to a P signal generator module that converts that analog signal having a value from -2 to -10 volts into a 20 to 100 milliamp P signal and then there is a logic level coming out of CPU2 I/O module which goes over to a P and brake signal generator module to turn the brake signal generator on or off as required to generate the 100 milliamps to zero milliamps brake signal.The P signal and the brake signal are put on train lines and go to each car vehicle for a multiple car vehicle train. The only vehicle computer CPU2 that is actually doing the speed control and start-up enable function is in the head end car of the train. However, the brake signals go to the propulsion and brake equipment 224 on each car. The propulsion brake control equipment 224 then converts these signals into motor current request, controlled motor current brake pressure and so on to where the vehicle motors and brakes 226 control the actual train velocity. The train actual velocity is sensed by tachometers 228 physically mounted on the motor axles, and the tachometer signals then come back into the CPU2 as an actual speed feedback.

In Figure 8 there is shown a schematic of the desired velocity system 300 in relation to a total movement control system for a train vehicle 302. The vehicle desired velocity control system 300 includes both hardware and software portions, but primarily it is a software routine using inputs from other subsystems which may be carried on the vehicle 302 and receive speed codes from antennas 306 and outputs the COC modified reference velocity 308 to the vehicle desired velocity system 300. In addition, two-speed error signals 310 and 312 and two dynamic toggle signals 314 and 316 are output to the car-carried ATO equipment 318. The car-carried ATO equipment 318 includes such things as the vital interlock board which is well known and is presently in commercial operation in the Sao Paulo train control apparatus.Each computer CPU1 and CPU2 carried on vehicle 302 determines a respective speed error and the two signals are fail-safe ANDed together and checked to establish that they are alike. if the checking of the speed errors is satisfactory, the final operation in each of the computer CPU 1 and CPU2 is to toggle an output bit art a 9 hertz rate; if either of these dynamic toggle signals go away, this indicates the associated computer is not running properly and the hardware in block 318 will shut down the vehicle speed control system. The ATO equipment 318 outputs several signals 320 labeled start-up conditions which will be explained in relation to the flow chart of Figure 9 and the PM number 322 to the vehicle desired velocity system 300.The PM Number 322 is a performance modification code; this is a code received from the wayside as a six-bit code asking for two things. One is to reduce speed and the other is to reduce the acceleration rate.

The propulsion and brake equipment 324 receives a start-up enable signal 326 from the vehicle desired velocity system 300 as well as a requested P signal 328 or a brake signal 330 directly to the propulsion control 324 during a rollback of the vehicle. The normal operation is for the propulsion and brake equipment 324 to be controlled by the Pl controller system 332 which is shown in greater detail herein. The normal outputs from the vehicle desired velocity system 300 is the desired or reference velocity, the action velocity 336 and a slow acceleration signal 338 and these are output to the Pl controller system 322 which, in turn, other than in rollback, supplies the P signal 328 and the brake signal 330 to the propulsion and brake equipment 324. The vehicle 302 is controlled by the propulsion and brake equipment 324.The tachometers 340 and 342 are coupled with the vehicle 302 to supply actual speed signals 344 and 346 to the car-carried ATO equipment 318. The Pl controller system 332 other than in rollback normally controls the vehicle speed. The program stop system 348 receives program stop signal as software interrupts from block 306 as the vehicle 302 passes the crossovers in a program stop tape located ahead of a station where the vehicle is to stop. The outputs for the program stop system 348 are the program stop velocity 360 and the look ahead velocity 352 which are supplied to the vehicle desired velocity system 300.

The speed command signal 360 is received from the wayside in the form of comma-free binary numbers. If there is no cutout car or performance reduction, the vehicle will run at the speed command velocity. These two modifications involve safety and when provided modify this speed command velocity to a lower value; one is the cutout car 71 command switch or the cutout car 86 switch, with each dropping a predetermined percentage of the speed command velocity. In addition, there is the program stop velocity 350 and the look ahead velocity 352 which can reduce the vehicle below the speed command velocity. The end result is that there are several different velocities determined in different hardware and in relation to different vehicle operations.The purpose of the vehicle desired velocity system 300 is to go through and sort out under the proper conditions which of the several different velocities is the minimum and is to be used. The final output is the desired velocity 334 which in general is the minimum of the other desired different velocities, depending on certain different cases such as which is the head end, which is the tail end, what switches are thrown. These are the reasons for the different velocity signals coming in. Another output from the routine 390 is a slow acceleration request 330 to the Pl controller system 332 which is derived through the performance modification determination.Also the start-up enable bit 326 is provided when a train is stopped and all conditions are set such that it is proper for the train vehicle to go, this bit is set and remains set for about four seconds until the train arrives at a speed of approximately 5KPH and then this bit is reset. Without this start-up enable bit the train could not start, so it is included in the vehicle desired velocity system 300 because it is necessary to be able to start the train from a zero speed.

In Figure 9A and 9C there are shown two separate sections of the vehicle desired velocity system program; one determines the desired velocity and the other determines the start-up enable. The desired velocity program section starts at block 400 and is called speed control. At block 402 the reference velocity is set equal to the ones reference velocity which was the output 308 shown in Figure 9 from the speed decoding routine. At block 404 the action velocity is set equal to the ones reference velocity. At this point in time the ones reference velocity is equal to the minimum of three things, namely the wayside speed command code velocity, the cutout car 1 reduced velocity and the cutout car 2 reduced velocity; both the reference velocity and the action velocity are set equal to the speed command velocity modified for the cutout car switches.To determine what the PM velocity is, which is the velocity as modified by the performance modification number, at block 406 a check is made to see if a PM number is provided; the PM numbers range from zero through 5, and if the number is zero, it is set equal to one at block 408 because the table shown in Figure 4B is set up with a bias and it is desirable to get the first number if there is none such that the default case is the performance modification of 1 for normal running. In this way the PM velocity is determined from either the bias number or the PM number is one. The PM bias at block 410 is the bias in the PM table. The PM table is shown in Figure 4B; PMVEL is the PM velocity table and the other table PMACC is the PM acceleration table.

The bias number is used to determine from these tables the PM velocity and the slow or fast acceleration. At block 410 the PM bias is set equal to the PM number minus 1. At block 412 the ith entry in the table is set equal to the bias number. At block 414 the PM velocity is found in the table at the ith location and is stored in the PM velocity storage location VELPM. At block 416 the ith entry in the acceleration table is found using the same bias to determine the PM acceleration and it is stored in location ACCPM. Two velocities have now been determined that the train can be controlled by, one is the reference velocity determined at block 402 and the other is the PM velocity determined at block 414.Block 418 determines which of these is the smallest; if the reference velocity is less than the PM velocity, then the controlling reference velocity is still less than the PM velocity. If the PM velocity is smaller than the reference velocity at block 418, then at block 420 both the action velocity and the reference velocity are restored equal to the minimum which is now the PM velocity.

At this point in time four different velocities have been considered to determine the minimum, namely the speed commanded reference velocity, cutout car 1, cutout car 2 and the PM velocity. A check is made at block 422 to see if a program stop is to be made; when a program stop is to be made, the PS flag is sett 1. If the PS flag is not set to 1, at block 424, the program stop velocity is set to 100KPH, which is the maximum number and therefore it can never be the lowest of the considered velocities. If a program stop is to be made, program stop velocity is obtained and a check made at block 426 to see if the reference velocity is less than the program stop velocity. If the reference velocity is less than the program stop velocity at block 426, the program goes to the start-up program.If the reference velocity is not less than the program stop velocity at block 426, at block 428 the reference velocity is set equal to the program stop velocity.

The start-up enable bit 328 shown in Figure 8 is determined by the program routine shown in Figure 9C.

The purpose of this bit to enable a train vehicle to start moving when it is in a stop or an extremely slow epeed condition, and as a fallout of this program routine if the vehicle is in rollback, the P signal and the brake signal are controlled directly from the vehicle desired velocity system 300 as shown in Figure 3 rather than going through the ramped Pl controller system 332 in order to get a faster vehicle control reaction to stop the vehicle. At block 430 a check is made to see if all the doors are closed; the doors should never be open if the vehicle velocity is greater than some small number such as 4KPH. The open doors signal is provided when the train vehicle is still moving very slowly to enable a faster passenger unload and load cycle at the stations.As the vehicle enters a passenger station a check is made to see if the vehicle is traveling less than 4KPH and if it is, the door open signal is provided and by the time the train is actually stopped the doors are opening. At block 430 a check is made to see if all the doors are closed; if the answer is no, at block 432 the reference velocity or the desired velocity is set to zero, and at block 434 the enable bit is set to zero and the program goes to the Pl controller system 332. If the vehicle is moving, for example at 60 KPH and the doors are open at block 430, it is not desired to stop suddenly or this might throw passengers out of the train vehicle; therefore the desired velocity is set to zero at block 432 and the program goes to the program of the Pl controller system 300 that will ramp the speed down at a controlled jerk limited rate. If the doors are open at block 430, it does not matter whether the vehicle is going fast or slow, unconditionally the desired velocity is set to zero and proceeded to ramp down. At block 436 all the doors are closed and a check is made to see if a rollback of the vehicle is detected in computer CPU2; in other words is the rollback bit equal to one indicating that a rollback is detected.A rollback is a train vehicle that is physically rolling backwards and is sensed by checking the phase of two tachometer signals from the same vehicle axle. This is a hardware check on one of the I/O boards and if the vehicle is rolling back, it should be stopped immediately without ramping down the speed by putting on the brakes fast. Block 438 makes the same check in relation to the other computer CPU1 to give two independent checks on a vehicle roilback condition; each computer uses a different pair of tachometers as shown in Figure 8 which is an improvement over the prior art practice. When a rollback is detected at block 440 the P signal is set equal to 20 milliamps which calls for - the vehicle brakes. At block 442 the brake signal is set to one which is the brake mode, and that will stop the vehicle immediately.If both rollback condition checks at blocks 436 and 438 are No, then the next check is in block 444 to see if the emergency brakes are on. The emergency brake is an operator manual hand brake. If the answer is yes, at block 434 the enable bit is set to zero. If the emergency brakes are not on, at block 446 a check is made to see if the reference or the desired velocity is less than 5KPH. There is only one vehicle condition where the reference velocity can be less than 5KPH and that is if the vehicle is in the process of making a program stop. If the vehicle is in the process of making a program stop, there is no need for the start-up enable bit to be set to one so at block 434 the enable bit is set to zero. At block 448 a check is made to see if the vehicle speed is greater than 5KPH and this is done using tachometer 4a coupled with the vehicle.If the vehicle is going greater than 5KPH, there is no need to set the enable bit to one so at block 434 the enable bit is set to zero.

The 6-bit commafree speed command codes are coming in from the wayside at an 18 Hz rate. Everytime a new speed command bit comes in the programs in Figures 9A and 9C are part of that interrupt routine and are executed at a rate of 18 times a second so from the time the program stop is lost at block 446 until the vehicle gets up to a speed of 5KPH at block 448 these programs will be executed many times. At block 450 a check is made to see if the vehicle is in the ATO mode of operation. If the answer is no, at block 452 a check is made to see if the vehicle is in the MCS mode of operation, which is manual with cab signals that have overspeed protection. The operator is receiving the speed command signals and he can manually control the vehicle to follow those signals.If the vehicle is in manual cab signal mode, at block 454 a check is made to see if there has been a request for power mode. If the answer is no, the vehicle is not going anywhere so at block 434 the start-up enable bit is set to zero. If the answer is yes, a request for power has been made and at block 456 enable bit is set to one to allow the vehicle to start. The start-up enable bit set to one at block 456 applies both to the manual control when the vehicle operation is under cab signals and the automatic mode of operation.

When the start-up enable bit is set at zero, the first check the vehicle desired velocity system 300 will make is to see if the vehicle is in manual. If it is, then that program ignores the start-up enable bit set to zero and the train starts moving in manual control by the operator. At block 456 the start-up enable bit is set to 1 if every condition above is met and satisfied and at block 434 the start-up enable bit is set to zero if any of the condition tests fail. At the end of the program routine shown in Figure 9C control is sent to the Pl controller system 332 which will in all cases except through the path through blocks 440 and 442 ramp the actual vehicle speed to the new desired speed and for the path through blocks 440 and 442 it is an absolute setting of the brakes.The output from blocks 440 and 442 operates differently and setting the brake signal equal to zero goes directly to the propulsion and brake control equipment 324 shown in Figure 3 to stop the vehicle fast and with the output from block 434 it is desired to stop the vehicle but not immediately.

The PM velocity table shown in Figure 9B is a table which is stored in Programmabie Read Only Memory.

The ID routine inputs and sorts out what particular code PM is for each of four or five different speed code signals and for a particular PM number this program goes into the table and finds the PM velocity that the train should travel at. As an example, for a speed code of 100KPH the PM number is 3 and this would indicate the third entry in the PM velocity table so the vehicle should be going 68KPH. The number that shows up in this table is scaled for use in the Pl controller system 332 and it is double the value desired by the speed code signal. The top entry in the table is 200, which is really for a speed code of 100KPH since all numbers in the table are multipled by 2 to get one more bit of accuracy. The top entry in the table is full speed ahead and the lowest entry is 44KPH with the slow acceleration.The other table is the acceleration table and there are three normal accelerations and three reduced accelerations as shown. PM number 1 is full speed and full acceleration. PM number 2 is 68KPH with full acceleration. Number three is 68KPH but with slow acceleration and so forth.

There are four ID antennas on each vehicle pair and there is received information coming in which information can be ID information, PM or relate to the door open condition. The ID routine inputs this information and sorts out what it is and stores the information in the proper place.

The programs shown in Figure 9 can have a variable execution time. The program is executed in the present system at an 18 Hz rate which is sufficient to control a large steel-wheel vehicle having a relatively slow response time. For a smaller car where the response of the vehicle is faster it might be desired to execute this program at a more rapid rate such as 54 times a second. The rate that this program and hardware is executed depends directly on the response time of the vehicle and with the available computer speed, this program can be executed at whatever time is required for the actual response time of the particular vehicle being controlled.

The variables involved such as the velocities primarily in the speed control can be scaled to get better response and better resolution; the factors can be scaled up or down. The program shown in Figure 9 doubles the speed variables in the tables; for example, if the vehicle is supposed to be going 30, the program thinks the vehicle is supposed to be going 60, which gives twice the resolution and again it is a variable that can be scaled up or down depending upon the requirements of a control system for a particular vehicle train.

The number of possible conditional checks provided in the program can be increased. At present cutout car switches, performance modification changes and program stop velocities are included. If in the future some other variation of speed is required, the program is set up to add an additional variable to cover this condition. At present the program is checking three different velocities; namely the cutout car modified velocity as accepted from the speed decoding routine, the performance modification velocity and the program stop velocity. This program takes the minimum velocity of these and sends it to the Pl controller system 332. The here-described speed control program shown in Figure 9 permits more PM values in relation to desired performance modifications.The present system has a program which as written can be modified to accept additional performance modifications as may be desired because of grades, vehicle weights, direction of travel and the like requiring different velocity profiles. The modification of the program involves adding more numbers to the tables shown in Figure 9B.

The program shown in Figure 9C directly controls the brake signal and the P signal in case of certain possible vehicle operating conditions such as a vehicle rollback condition or the doors open when they are not supposed to. If the doors open when the vehicle is going less than 5KPH, this is acceptable; on the other hand, if the vehicle is going 100KPH and the doors open, to avoid a sudden stop by a fast application of the brakes which would throw people out of the open doors the program goes to the Pl controller and ramps the speed down.

The start-u p enable bit can be reset and set at different velocities since in the program it is just a number.

At present, when the vehicle starts up and all conditions are met the start-up enable bit is sent to the vital interlock hardware module to bypass the tachometer integrity check and permits the vehicle to start to move; as soon as the vehicle reaches about 5KPH the start-up enable bit is reset to zero. If desired, the particular program can be modified to change that number from 5KPH to 6,7,8 or whatever speed limit is required.

The program shown in Figure 9 is executed in computer CPU2, and it is executed as a result of the 18 Hz one's clock interrupt. At the present time it runs at an 18 Hz rate, but this could be changed to a faster of slower rate in response to other suitable interrupts if desired. A different rate could be obtained by dividing or multiplying one of the available clock rates. The control from this routine goes to the Pl controller system 332 which, in turn, uses the output signals from this vehicle desired velocity system 300 in all cases except where the P signal and brake signal in Figure 9C go directly to the control logic for the brake signal.

In Figure 10 there is shown the start-up time gate function provided as part of the operation of the vehicle desired velocity system shown in Figure 8. The zeros speed reference signal is supplied in conjunction with an actual speed signal from tachometer 3a to a zeros speed error block 500. With the output of the zeros speed error block being the zeros speed error signal in binary form which is supplied to a not-overspeed check block 502 the output of which is applied to an AND gate 504 in conjunction with the binary zeros speed error such that the output of the AND gate 504 is the zeros speed error when the not-overspeed check at block 502 is satisfied.The ones speed reference is applied in conjunction with the vehicle actual speed from the tachometer 4a to the ones speed error block 506, the output of which is applied to a not-overspeed check block 508 and to one input of an AND gate 510. The other input of the AND gate 510 is satisfied when the not-overspeed check at block 508 is satisfied. The output from the AND gate 510 is the binary ones speed error signal.The zeros speed error signal is applied to a DA converter 512 and the ones speed error signals applied to a DA converter 514 such that the respective analog outputs of the latter two circuits is applied to an overspeed and balance apparatus 516 including a not-overspeed block 518 which provides an output when the zeros speed error is below a predetermined value and the ones speed error is applied to a not-overspeed block 520 which provides an output when the ones speed error is below a predetermined value with the respective speed errors being applied to a balance circuit 522 such that an output is provided from the balance circuit when less than a predetermined difference exists between the zeros speed error signal and the ones speed error signal.The output from the overspeed block 518 is applied to one input of an AND circuit 524 with the output of the balance circuit 522 being applied to the other input of the AND circuit such that the AND 524 provides an output when there is not an overspeed condition as in relation to the zero speed error signal and there is a satisfactory balance between the two speed error signals as indicated by the output from the balance circuit 522. The AND gate 526 provides an output when the AND gate 524 energizes one input of the AND gate 526 and when the overspeed check circuit 520 energizes the second input of the AND gate 526. In addition, a tachometer integrity checking apparatus 528 is provided including a dynamic check 530 responsive to the output of the tachometer 3a and a proper phase check 532 responsive to the output of the tachometer 3a and the output of the tachometer 3b both of which tachometers 3a and 3b are operative with a common axie of the passenger vehicle 302. When the output signal from the tachometer 3a is dynamic the dynamic check 530 provides an output to the OR gate 536. When there is a proper phase relationship in the order of 90 degrees difference between the output signal from the tachomter 3a and the output signal of the tachometer 3b the proper phase check 532 provides an output to OR gate 538.The output signal from the OR gate 536 energizes a charge pump 540 which, in turn, provides one output to a fail-safe AND gate 542; the other output of which is energized from the AND gate 526. The output signal from the OR gate 538 is applied to a charge pump 544, which provides an output signal to the fail-safe AND gate 546; the other input of which is energized from the fail-safe AND gate 542 such that the output signal from the fail-safe AND gate 546 is provided when there is not an overspeed condition of the vehicle sensed when there is a predetermined balance between the zeros speed error signal and the ones speed error signal and when the tachometer integrity apparatus 528 indicates a satisfactory integrity of operation of the tachometers 3a and 3b.A start-up time gate 548 is responsive to an enable bit from the computer which enable bit is provided by the program shown in Figure 9. When this enable bit is supplied to energize the start-uptime gate there is a capacitor within the start-up time gate 548 which has a discharge time in the order of four seconds such that when the enable bit from the computer is supplied to the start-up time gate 548, an output signal lasting for four seconds is applied to each of the OR gates 536 and 538 such that the respective charge pumps 540 and 544 are energized and providing the output signal is supplied by the AND gate 526, then the fail-safe AND gate 546 for a period of four seconds will provide its output signal, which output signal from the fail-safe AND gate 546 is converted into a direct current voltage to pick up a relay which couples the P signal to the train line such that each passenger vehicle in the train can respond to the P signal through its respective propulsion equipment to cause the passenger vehicle propulsion motor to be energized and move the vehicie. If any of the input conditions shown in Figure 10 is not satisfied, then there is no output signal from the fail-safe AND gate which does not pick up the relay coupling the P signal to the train line such that there is no P signal provided to the train line which causes the propulsion motors in each of the vehicles to go into the brake mode of operation.

The start-up time gate 548 shown in Figure 10 includes a capacitor having four states of operation. The normal state of the capacitor when the train is running is the discharged state. if the train should stop for some reason or the doors should open, then the enable signal from the computer is set to "0" and the capacitor begins to charge and it requires eight seconds to become fully charged. After the capacitor is fully charged it will stay in this condition and provide no output from the start-up time gate 548 until the enable signal is provided by the computer.

During normal running of the passenger vehicles if for some reason the speed error balance is lost at circuit 522 or the tach integrity is lost from the apparatus 528 or if an overspeed condition of the vehicle is sensed at one of the blocks 502, 508, 518 or 520, then the output signal from the fail-safe AND gate 548 will disappear and this operates to remove the P signal from the train line. On the other hand, when the train is stationary there is no output signal from the tachometers coupled with the vehicle so there is no P signal coupled to the train line. The start-up time gate 548 functions during start-up to provide output pulses for a predetermined period of four seconds through the OR gates 536 and 538 to provide an initial pseudo tach integrity signal to allow the train vehicles to start.

The operation of the speed error blocks 500 and 506, the not overspeed checks 502 and 508 and the AND gates 504 and 510 is provided within the software of the concurrently filed and above-referenced speed decoding and speed error determining application. The same general functions that are presently being performed in the Sao Paul train control apparatus that has been in actual operation for two or more years and correspond with the apparatus shown in Figure 5.

Claims

1. Apparatus for controlling a train of vehicles using a determined desired velocity of a train of vehicles in response to one of a reference velocity signal, which is established by an input command velocity signal that can be modified by a cut out car condition or a performance restricted condition, and a program stop velocity signal, the apparatus comprising means for providing a velocity control signal for said train in response to the lowest of said reference velocity signal and said program stop velocity signal, means for providing a start-up enable signal to permit the train to move in response to said velocity control signal requesting greater than a first predetermined velocity and in response to the actual velocity of the train being less than a second predetermined velocity.

and means for providing an effort request signal for controlling the actual velocity of the vehicle by comparing the desired velocity signal with the actual velocity signal.

2. The apparatus of claim 1, with said train having at least one door, and including means responsive to a door being open for making said velocity control signal have a zero value such that the enable signal providing means does not respond to a velocity control signal requesting greater than said first predetermined velocity.

3. The apparatus of claim 1, including means for stopping the train in response to a roll back tendency of the train.

4. The apparatus of claim 1 for a train having vehicle brakes and a brake mode of operation, including means responsive to a roll back condition of the train for providing the brake mode of operation for the train, with said roll back responsive means providing a minimum effort request signal for determining the application of the vehicle brakes.

5. The apparatus of claim 1 responsive to periodic reference velocity signals, with said velocity control signal being periodically provided in accordance with the occurrence of the periodic reference velocity signals.

6. The apparatus of claim 1, with the start-up enable signal being provided until the train reaches a selected velocity at which the start-up enable signal is reset to zero.

7. The apparatus of claim 1, including means responsive to a first undesired operation of said train for making the velocity control signal request less than said first predetermined velocity.

8. The apparatus of claim 1, with said first predetermined velocity and said second predetermined velocity being substantially the same.

9. The apparatus of claim 1, including said velocity control signal providing means having a storage table of a plurality of predetermined velocity control signal values for each value of said reference velocity signal, and with the enable signal providing means responding to one of the plurality of predetermined velocity control signal values in accordance with the modification of the input command velocity signal.

10. The apparatus of claim 1, with said effort request signal providing means including a controller having a proportional characteristic and an integral characteristic, with said integral characteristic being clamped to keep it within predetermined bounds in accordance with the difference between said actual speed of the vehicle and said desired velocity.

11. The apparatus of claim 1 for controlling a passenger vehicle having a propulsion motor and brake equipment, including means for detecting an overspeed operation of the passenger vehicle for applying a brake effort to reduce the velocity of the vehicle until the overspeed operation is corrected and then removing said brake effort such that by the time the brake effort is actually removed the vehicle will be at substantially the requested velocity of operation.

12. The apparatus of claim 11, with said overspeed detecting means setting the effort request signal to a predetermined value when the overspeed operation is corrected for removing the brake effort.

13. Apparatus as in claim 10, including means for determining the integral characteristic in relation to the proportional characteristic such that when the controller is in saturation the integral operation is substantially zero to prevent said integral operation from causing an overspeed or an underspeed of the passenger vehicle.

14. The apparatus of claim 13, including means for holding said integral operation substantially at zero until the actual speed of the vehicle is within a predetermined relationship with said first velocity signal.

15. The apparatus of claim 14, when said first velocity is provided in accordance with one of the input command velocity signals and the input modified velocity signal, including means responsive to a second velocity signal having a predetermined relationship to said input program stop velocity signal for causing said first velocity signal to be provided in accordance with said input program stop velocity signal.

16. The method of determining the velocity of a train of vehicles in response to one of a reference velocity signal and a program stop velocity signal, including the steps of providing a velocity control signal for said train in response to a selected one of the reference velocity signal and the program stop velocity signal, and determining an effort request velocity signal to control the velocity of the train in response to the velocity control signal requesting greater than a first predetermined velocity and in response to the actual velocity of the train being less than a second predetermined velocity.

17. The method of claim 16, including the step of responding to an undesired operation of the train for making the velocity signal request less than said first predetermined velocity.

18. The method of claim 16, including the step of responding to an open door on said train for controlling the velocity of the train to become zero.