GB2563398A

GB2563398A - Method of determining the position of a model train

Info

Publication number: GB2563398A
Application number: GB1709346.9A
Authority: GB
Inventors: John Jones Peter
Original assignee: Individual
Current assignee: Individual
Priority date: 2017-06-12
Filing date: 2017-06-12
Publication date: 2018-12-19
Anticipated expiration: 2037-06-12
Also published as: GB2563398B; GB201709346D0

Abstract

System for determining position of a vehicle, e.g. model train, comprises: signal generator 112, 114 mounted on wheel 108 to provide a signal depending upon the wheels rotation; sensor 110 to detect the signal and generate pulses in response; counter 115 to count the pulses; and transmitter 122 to transmit the number of pulses to remote receiver 118. The signal generator may be magnets and the sensor may be a Hall effect, reed switch, reluctance or proximity sensor. Also disclosed is a control system for a model railway including a display dashboard, speed software and input via a mobile device. Also disclosed is a system for determining a vehicles position and speed comprising: source of electromagnetic radiation; reflected radiation sensor; and controller to switch the sensor into active mode for a duration based on the vehicles speed; wherein distance travelled by the vehicle is transmitted to a controller. Also disclosed is a system for transmitting the position of a vehicle on rails using a modulated high frequency signal transmitted through the rails. Also disclosed is a method of recording the location of a vehicle on rails comprising: placing the vehicle at a datum; traversing the vehicle along the rails; deriving the distance travelled; and transmitting the distance travelled to a remote receiver.

Description

Method of determining the position of a model train

The present invention relates to a method of determining the position of a model train. More particularly the invention relates to a system of, and method for, determining the position and speed of a vehicle with at least one free running wheel.

More particularly, but not exclusively, the invention relates to a system of, and method for, determining the position and speed of a vehicle, such as a toy or model vehicle, travelling over a surface such as along rails or a track.

The invention is particularly well suited for use with a toy or model vehicle, such as a toy train or model train or carriage, as it is able to provide an indication of the precise location of the toy, model train or carriage within a model railway layout.

Previously verifying the location of model trains, within a model railway layout or installation, has been difficult especially with larger railway layouts, because such model railway installations were often separated into several independent zones. Each zone required its own wiring and control unit. As a consequence of this, the cost of model railway installations was expensive, particularly as the size and complexity of model railway installations grew because each zone required a dedicated control system and its own wiring. In addition as size and complexity of layouts grew the ability to locate the precise whereabouts of a train because increasingly difficult.

The present invention overcomes these problems and eliminates the need for such wiring and additional controllers, as well as improves the accuracy of locating a train, so enabling greater flexibility when positioning accessories, such as points and level crossings; station furniture, such a lights; and ancillary items, such as signal boxes or water tanks, that are typically used in model train layouts.

In addition, the present invention enables close control of individual trains within a complex installation due to its capability of precisely locating a train with respect to a reference or datum.

Automatic safety features can be integrated into a model railway installation control system. For example, a collision sensing means may be provided which prevents two or more trains, on the same section of track, from colliding with one another. This sometimes has occurred when one train stops unexpectedly or the exact location of each train was not known. The present invention enables this problem from occurring.

According to a first aspect of the present invention there is provided a system for determining the position of a vehicle with at least one free running wheel comprising: a means mounted on the wheel for providing a varying signal in dependence upon the rotation of the wheel; a sensor which is mounted on the vehicle, senses the variation of the signal and generates pulses in response thereto; a counter counts the number of pulses in a time interval and a transmitter transmits the number of pulses to a remote receiver.

The unpowered vehicle is ideally towed (or shunted) by a powered vehicle, such as a locomotive.

Preferably a counter counts the number of pulses and the number of pulses is transmitted to a remote receiver which communicates the number of pulses to a controller which processes data received from one or more transmitters. Transmissions of pulses may be accompanied by an identity signal that is specific to an individual transmitter so that a carriage or train can be identified.

The system eliminates errors in position that occurred as a result of wheel slippage which occurred with powered wheels. Elimination of errors is achieved by ensuring the position sensor is located on an unpowered wheel, which is free running, or on its axle, where no wheel slippage occurs. By measuring the rotations of the unpowered wheel an absolute distance is obtained. This is due to the fact that the sensor measures the wheel which a greater coefficient of friction with respect to a driven wheel. The system also eliminates differential errors that arise as a result of the different distances travelled by wheels around bends which occur as a result of a slightly lesser distance travelled by a wheel on an internal curve compared with that 2 distance travelled by a wheel on an external curve. One way in which this is achieved is by mounting a sensor on an axle with a second, smaller wheel at its opposite end. The second wheel has a smaller diameter for aesthetic purposes only and does not contact the rail so does not affect the measured number of turns of the first free running wheel. Another way of achieving this is by decoupling the two wheels (one with and one without a sensor) or by having separate wheels mounted on supports without any axle therebetween.

Importantly the sensor is mounted on a free running wheel of an unpowered vehicle, such as a carriage, trailer or wagon that is being towed or shunted, for example by a locomotive. In an alternative embodiment the free running wheel may be mounted on the bogey of a locomotive. What is important is that the wheel is free running so that it does not slip or skid and only rotates in contact with the rail. This feature overcomes the problem of wheel slippage encountered when previously attempting to measure speed of a locomotive vehicle, especially when the locomotive vehicle towed trucks, wagons or trailers.

The problem of wheel slippage often arose when accelerating, especially from standstill. Wheel slippage occurs due to the need to overcome dynamic friction and continues until traction becomes effective. Wheel slippage occurs in traction due to low adhesion between wheels and rails. A wheel set on a locomotive accelerates more quickly than the locomotive moves and this has given rise to wheel spin. Sometimes wheel spin can damage the traction system or result in damage to the wheel of a locomotive or a rail. If an attempt is made to measure distance by relying upon the number of turns of a locomotive with wheel spin an erroneous value is obtained due to wheel spin. Therefore if the counter were to be connected to the wheel of a locomotive and count the absolute number of turns a false reading would be obtained for the distance the train has travelled.

The invention however counts the number of turns of a free running wheel which is simply free to turn when in contact with a surface and the distance travelled (D) is derived from the number of turns of the free running wheel (N), using, D = 2Νττγ where (r is the radius of the wheel contacting the rail).

The fact that there can be no wheel slippage means that the number of turns is directly proportional to the distance travelled.

A timer is used to compute the speed as the rate of change of position. The invention overcomes this by mounting a counter on a wheel of a carriage or truck that is moved (pushed or pulled) by the locomotive and therefore a true reading of distance travelled is obtained, rather than one based on number of turns, some of which might have arisen due to wheel spin or slippage.

Location specific data may also be used to update a display as to the position and identity of a train which is connected to the carriage or truck. This data is ideally used to control other devices, such as signals and crossings. The display may be incorporated in a portable computer such as a laptop or a tablet device; or the data may be presented on a standalone display or on a screen of a personal computer configured with a track layout in a similar manner to that viewed by a signal box operator.

In a preferred embodiment therefore data received by a computer is optionally processed and, as it provides such precise information about the status, identity and location of a train, a control room of a signal box may be replicated. As such an improved level of control and realism can be introduced into a model layout.

Preferably the transmitter in the unpowered vehicle communicates with the remote receiver via a radio frequency (RF) link. Ideally radio frequency (RF) communication is via the tracks over which the unpowered vehicle travels. Data is transmitted from the transmitter optionally by modulating an RF signal across the tracks, via metal wheels on the truck or carriage, by way of a means for generating a radio frequency (RF) signal.

Preferably the count is achieved by mounting a magnet or magnets on the wheel or on the axle of the wheel. The sensor advantageously varies its output voltage in response to a varying magnetic field that is caused as the, or each, magnet approaches and moves away from the sensor. As the wheel of the unpowered vehicle rotates, due to being towed by the locomotive, magnetic flux lines affect the one or more magnetic sensors. This activates the sensor(s) producing an electrical output.

The magnetic sensor(s) preferably include: a Hall effect sensor, a reed switch sensor, a reluctance sensor and/or a proximity sensor. Ideally at least one Hall effect sensor is used, thereby enabling the position and/or speed to be measured. In its preferred form the, or each, Hall effect sensor operates as an analogue transducer whose voltage output is sent to the transmitter. Therefore as the wheel rotates the magnetic sensor is activated and deactivated producing a series of pulses. Thus by counting the pulses the train position can be determined with respect to a reference datum, as can the train speed. Other sensors may be used, examples include: a sensor that responds to an induced current, a sensor that senses a variation in capacitance, an optical sensor or an acoustic sensor.

Alternatively wheel rotation can also be counted using an optical sensing means. Optionally a system for determining the position and speed of a vehicle includes: a source of electromagnetic radiation mounted on the vehicle which is directed to a surface over which the vehicle travels; a sensor senses the presence (or absence) of reflected radiation; and a control means switches the sensor to an active mode for a duration that is dependent upon the speed of the vehicle, during which active mode, radiation is detected and a signal indicative of distance travelled is derived.

In one preferred embodiment the system is pre-calibrated with information relating to the distance between sleepers or rail spacers. Alternatively a user is able to input the spacing or use the source of electromagnetic radiation and the sensor in order to calibrate the system by determining the distance between sleepers or rail spacers directly.

An initial reference point on a railway layout provides a reset point or datum to reference the train position to a datum or zero position. The train position is then determined by counting the pulses from an encoder from the reset point or datum. This reset point provides an absolute reference and counting may be set using a variety of methods. For example the datum may be determined using a magnetic device, an optical means, a proximity sensor or an ultrasonic sensor.

Preferably the counter is reset at regular intervals and ideally when the sensor, which is mounted on the truck/vehicle or train, passes a predetermined point or datum. An advantage of this is that if there is an error in the recorded distance travelled, this error is prevented from accumulating each time the truck/vehicle or train or unpowered vehicle passes the reset position.

As the train now has an on-board means of determining its absolute location and speed, the position and speed data may be relayed to a remote controller. The position and speed data may be relayed via a wireless transmitter/transceiver or via the railway tracks.

According to a second aspect of the invention there is provided a system for transmitting the position of a vehicle moving on rails comprising: a means for generating a radio frequency (RF) signal; and a means for modulating a transmitted signal on tracks such that information from the vehicle is transmitted to a remote location via the tracks.

Train speed is determined by counting the number of reflected pulses and a using this information with a known spacer distances and the rate at which pulses from the encoder receiver are received.

The invention overcomes the aforementioned wiring problems as it in the first aspect absolute position of a railway locomotive is determined and as a consequence, the location of the model train may be transmitted via the railway tracks.

Preferably a discriminator is provided in order to reject false signals and to place the sensor, as well as any processing logic associated with the sensor, into a state of readiness so as to anticipate the arrival of a sequence of reflected signals.

Advantageously a filter is used to improve discrimination of the sensor so that the sensor ignores false pulses. The filter is controlled with knowledge of the speed and acceleration (or deceleration) thereby anticipating the arrival of signals to be detected and is able to reject false signals.

As information is known about the speed, direction and location of a vehicle, such as a model train, it may be used as part of an overall control system to enable the user to control other devices or items in a rail network infrastructure, such as for example points, barrier crossings, signal controls and signals. Shunting operations can therefore also be accurately controlled where wagons need to be coupled and uncoupled.

The electromagnetic radiation is ideally infra-red (IR) radiation and preferably IR radiation whose wavelength lies between 700 and 1000 nanometres. A reflected beam of radiation is sensed by a sensor which is different to the signal received from track spacers and this is used to determine the position moved by the train.

In use the system is mounted on the vehicle and utilises the difference between the nature of reflected radiation, from ballast between railway spacers and radiation reflected from railway spacers or sleepers. An optical encoder is mounted on an underside of the vehicle or model train so as to be able to view rail connecting means (sleepers) as well as spaces between the rails.

The electromagnetic emitter, which is preferably an infra-red device, is ideally located adjacent the receiver. Alternatively emitter and sensor may be arranged one in front of the other.

In either of the aforementioned embodiments, transmission of information from the train, for example its speed, direction or location, is via an RF channel defined by the rails; and transmission to the vehicle, for example from a controller, is via a different channel which, may be an infra-red signal, but is preferably by way of a short range wireless protocol connection, for example one which uses a Bluetooth (RTM) device. The two channels operating together, provide full duplex transmission to and from the vehicle.

Absolute location of the vehicle is determined by deriving the position travelled from a known datum reference point and the pulse count when direction demand is taken in to account.

According to another aspect of the invention there is provided a method of recording the location of vehicle having a free running wheel on rails comprising the steps of: placing the unpowered vehicle at a datum in a railway network; recording the datum; traversing the unpowered vehicle along the rails to a desired location; deriving the distance traversed by the unpowered vehicle and recording an end location by transmitting a signal indicative of the distance traversed to a remote receiver.

According to a further aspect of the invention there is provided a method for transmitting the position of a vehicle moving on rails comprising: the steps of generating a radio frequency (RF) signal and transmitting a signal from the vehicle to a remote location and recording the vehicle position in a memory means in a receiver at the remote location.

The remote receiver is preferably included in a master controller that operates in accordance with software and extracts train identity data and location specific data from signals received form the vehicle and uses these to control a network of trains and/or signals and/or other peripheral devices. As in the other embodiments data is transmitted by modulating an RF signal carrier and is received at the master controller.

Absolute location of the vehicle is determined by deriving the position travelled from a known datum or reference point and multiplying the number of pulses counted in order to derive the precise distance travelled. Information with respect to the train position may be transmitted to a master controller by a different method to the one used by the master controller to communicate to the vehicle. In this sense full duplex communication is achieved between the master controller and the vehicle by communication via separate channels.

The carrier frequency which has been chosen allows inherent inductance and capacitance that is present between the railway tracks, to provide a transmission line which allows for almost lossless transmission between the train and the controller. This method does not require intrusive aerials and also only requires one radio receiver for an entire layout as it transmits information between all trains to and from the master controller.

In a particularly preferred embodiment a model railway set is supplied with a controller that is adapted to operate a plurality of peripheral devices in accordance with information derived from the speed and location of a train so that the data relating to the train position and/or its speed is used by the controller to control the peripheral devices. These peripheral devices may be connected to a communication network and include devices such as: points, barrier crossings, signal controls and signals all of which are addressable by the controller.

Also, due to almost zero attenuation between transmitter and receiver, excellent signal-to-noise ratio (SNR) is achieved and this provides an extremely reliable RF channel and a reliable connection. As a result previous problems associated with radio communication due to nulls, reflections and attenuation due to poor transmission mediums are avoided.

The method of communication via railway lines differs from existing communication techniques which employ rails as induction loops, as according to this aspect of the invention the rails behave in a similar manner as a coaxial cable for radio frequency signals transmitted. In prior art systems a single rail was used to radiate an electromagnetic field to form a ‘go’ path of an induction loop. The return path was a conductor, which was spaced from the ‘go’ path in order to ensure a large radiated magnetic field. This was both cumbersome and unreliable.

The principle of a transmission line requiring two conductors in parallel, and in close proximity to prevent electromagnetic radiation leakage is therefore considered to offer a number of advantages. The magnetic fields generated by signals on each rail act in opposite senses, one to another, and so tend to confine the RF signal which results in near lossless transmission.

Each transmission device has an RF signal generator that operates at a very high frequency compared with an induction frequency band. Typically the frequency is in excess of 300MHz, most preferably in excess of 400 MHz.

Optionally a display is provided on which the train position and/or its speed are presented in the form of a computer generated image.

A preferred embodiment of the invention will now be described, with reference to the accompanying drawings, in which:

Figure 1 is a partial plan diagrammatic view of a railway line showing two parallel tracks and rail spacers or sleepers;

Figure 2 shows the position of an infra-red transmitter and detector, and the path of beams from one to the other being reflected off a rail spacer or sleeper;

Figure 3 is an example of a gate array which generates clocked pulses which are used as part of a discriminator;

Figure 4 is a diagrammatic view of a section of railway that is operating as a transmission channel for an RF signal and depicts elements of inductance and capacitance;

Figure 5 shows a diagram illustrating how discrimination is achieved with a gated pulse train which counts true pulses and rejects false pulses;

Figure 6 shows a diagrammatic view of a section of railway and illustrates the principle of how a railway line acts as an induction loop;

Figure 7 shows an alternative embodiment of a Hall effect sensor; and

Figure 8 is a diagrammatical view of system determining the position and speed of an unpowered vehicle.

Referring to the Figures, in particular Figures 7 and 8 there is shown a diagrammatical example of a system that determines the position and speed of an unpowered vehicle, such as a toy carriage or toy truck for use with a railway set.

The system determines the position of the unpowered vehicle, for example as it is being towed by a powered vehicle. The system comprises: a means mounted on a wheel of the unpowered vehicle for providing a varying signal in dependence upon the rotation of the wheel. A sensor, as described in greater detail below, is mounted on the vehicle and senses the variation of the signal and generates pulses in response thereto. A transmitter, which is ideally an RF transmitter, transmits the pulses to a remote receiver which derives the location of the position of unpowered vehicle in a railway layout

The position/speed sensor senses the variation of a magnetic flux from one or more magnets located on the wheel. If two magnets are offset or three magnets are arranged in an asymmetric manner, the direction of the unpowered vehicle can be derived. The flux varies with the rate of rotation of the wheel and is used to provide a signal indicative of speed of the unpowered vehicle. The transmitter transmits the signal to a remote receiver. The system includes a receiver that communicates to a master controller which processes data received from one or more transmitters.

The, or each, sensor is mounted on a wheel of the unpowered vehicle that is being towed. A counter connected to the wheel of a locomotive distance travelled (D) is derived from the number of turns of the wheel (N), using, D = 2Νττγ where (r is the radius of the wheel contacting the rail).

In a preferred embodiment only one wheel on an axle is actually in contact with the rail as this has been found to be more accurate than when two wheel are in contact with a rails as there is a slight discrepancy in difference between the inside of a curved track and the outside rail of a curved track. Other means may be used to remove this discrepancy, for example an averaging of the two wheels but this is more costly and complicated.

A timer is ideally used to compute the speed as the rate of change of position. In another embodiment a transmitter 122, in the unpowered vehicle, communicates with the remote receiver 118 via a radio frequency (RF) link. The radio frequency (RF) communication may be wireless or via the tracks 11 over which the unpowered vehicle travels.

A counter 115 counts pulses from a Hall effect sensor 110 which senses transitioning magnetic fields from magnets 112 and 114 that are mounted on the wheel axle or on the side of the wheel 108. A magnetic sensor 110 is mounted in this case to the base of the train or truck 102 or carriage body or wheel assembly structure. The magnetic sensor can be of many different types Hall effect, Reed Switch, reluctance sensor or proximity sensor. As the wheel 108 rotates due to train movement the magnetic flux from magnets 112 and 114 lines up with the magnetic sensor 110. This activates the sensor 110 producing an electrical output in the form of pulses as shown in Figure 8.

Therefore as the wheel 108 rotates the magnetic sensor 110 is activated and deactivated producing a chain of pulses. By counting the pulses at counter 115 the train position can be determined with respect to a reference or datum and the train speed can be determined by differentiating the number of pulses with respect to time at the microprocessor or at the controller 120. Wheel rotation can also be counted optically or many other methods.

A counter 50 counts pulses and uses the total to provide an indication of total distance travelled by dividing the total distance counted by the time taken to travel that distance. An instantaneous indication of speed is obtained by counting pulses over a shorter time duration, say 0.1 to 1 second, and dividing this by the time interval. The counter 50 may be reset in order to initiate a reference position. Resetting the counter may be achieved by sending a counter reset signal via a wireless communication link, such as Bluetooth (RTM) connection or an encoded infra-red signal, from a controller 40.

The instantaneous train speed therefore is the distance between a leading edge of the sleepers or spacers (constant) divided by the time taken to travel between the leading edge of one pulse to the next pulse.

The train position is the number of pulses counted from a pre-set reference point multiplied by the distance between leading edges of the pulses. The position of the train 19 also takes into account the direction of travel of the train and this is derived from the controller 40 which is also used to control speed and direction of trains.

The position and speed of the train 19 may be used as information to allow the user to make decisions about the following peripheral devices and settings. These peripheral devices include, but are not limited to: stopping positions in the railway network layout; signals (not shown); barrier crossings (not shown); points (not shown); and separation distances of two or more trains.

It is understood that a control system that includes the invention may be adapted to use information from trains to display respective train identities and their positions on a remote display. Errors that might occur between trains of different types and tracks of different types are therefore greatly reduced if not eliminated. Their speed and position are provided in real time. Furthermore layout assembly and connections are much quicker and easier to create and control than in previously available ‘zoned’ systems.

Operation of digital filter 18 is shown diagrammatically in Figure 5 and the filter 18 plays an important role in how signals S1 and S2 are counted. Operation of the filter 18 is now described.

There now follows a detailed description of a preferred embodiment of a digital train positioning system. The positioning system is based on knowing the precise train location of a carriage at any instant in the railway layout. This is achieved by moving the unpowered vehicle or carriage to a desired location and recording the position of the unpowered vehicle, for example by rolling the unpowered vehicle or carriage by hand or by towing it with a powered vehicle.

As a result of the wheel mounted means a user is able to count the precise distance from the datum by virtue of rotation of rotation of the wheel of the unpowered vehicle for providing a varying signal in dependence upon the rotation of the wheel; a sensor is mounted on the vehicle which senses the variation of the signal and generates pulses in response thereto; and a transmitter transmits the pulses to a remote receiver.

Knowledge of the precise location of the train is consequently used to control track infrastructure such as signals, points, barrier crossings, train stopping position, and many other features including precise train speed relative to track scale.

The train position is communicated back to the base station using the track as a transmission line at High Frequency (HF) The HF communication has no effect on the 20 kHz DCCC signal which also goes down the track.

The train position is generated from a position sensor mounted under a truck or carriage that is pulled by a locomotive using power from the track. The train position is measured with respect to a reference point (not shown) on the track which resets the train position to zero once the train passes by that reference point. The train position is transmitted to the base station and once recorded can be used to locate and control infrastructure as directed by a digital controller (DCCC).

The aforementioned system will now be described with reference to certain commands and control signals in which the number of trains which can operate with active communication to the base station is limited by the RF link and is typically at about 20.

The recommended RF high frequency (HF) link range if operated via a wireless is about a 20-30 metre radius. Ideally the antenna is located in the centre of the layout. Typically accuracy of train location is around ±28mm and performance is improved on a well layed out track and a locomotive that runs well at slow speeds.

Base Station Key Pad Functions *999 sets all positions back to default positions * 001 programs the main barrier crossing start point for barrier lights to start flashing * 002 is the finish point.

*003 programs the second barrier crossing start point.

*004 programs in the finish point for the second barrier *005 programs in the point at which the train slows down to collect loop from

Signal Box Functions *006 programs in the point at which the train will speed up after collecting loop *007 programs in the point at which the train will stop as a result of an emergency stop.

*011 programs in the point at which the train will stop within the station.

*012 programs in the point at which the train will stop to take on water.

*013 programs in the point at which the train will slow to 12 MPH ready for the points.

*014 sets the signals to red and the signal box lights on.

*015 sets the point at which the points will change from mainline to branch line.

*016 sets the stopping position on the branch line for the train.

*017 sets the point at which the points switch back to main line and the train speeds up.

#900 sets the program to beginning.

#897 monitor displays train position in bits. 1 bit = 7.33mm.

#896 monitor displays train speed in MPH.

#899 allows train speed, stops and starts to be controlled manually.

#898 allows train speed, stops and starts automatic control

Specific Programming Positions program in *999=default positions and #900 = start program at beginning and #899 = manual speed control.

Allow train to go round track at least once and check crossing LEDs are operating in the correct positions with respect to the train position as a result of the default positions.

Use slow speed to drive the train around the track to the required position and stop very gently at the position required. A plastic object which is too big for the train to move can be placed at the stopping position and allow the train to gently run in to the object and thus hold train at the correct position while programming in the position

Always allow the train to go thought the magnetic datum before stopping the train at the required position.

Check each of your new program in positions by putting the train back into automatic mode # 899 and restart program at beginning #900 and check the train dose the correct function at the new position.

Trouble Shooting

Check the LED on the base station is flashing which means the train is in communication with the base station via the wireless link. If not the contact between the train and the lines is the most likely problem.

The position of the wireless antenna may need to be changed.

The barrier crossing LEDs are not functioning correctly may be due to the train is not being reset by the magnetic datum very unlikely let the train go thought the Datum again.

System does not operate as it should reset system back to start #900 If programming has got confused - reset system to default positions *999 and reset program to start #900

Ideally communication and control electronics are miniaturised onto a pre-production PCB to fit in the truck or carriage.

Preferably carriages and track have to be modified to allow electrical pick up from wheels along with other small modifications.

Software is ideally compatible with existing software such as RailMaster ™ control software.

An alternative embodiment of the invention is described with reference to Figures 1 to 5. There is shown a model railway track 11 having parallel metal rails 10 separated by plastic spacers 12. The distance between the spacers 12 is constant with only minor variations at railway points (not shown) and crossings (not shown). In use, the railway track 11 is typically laid on a table (not shown) and may or may not be back filled with imitation ballast 15.

The railway spacers 12 and the ballast 15 between the spacers 12 therefore form a simple array of what may be considered barcodes that can be read optically by the contrast between reflected (infra-red light) radiation from the spacers 12 and from the ballast 15. These barcodes are detected by one or more optical sensing means 17

20, described in detail below. The optical sensing means 20 in the preferred embodiment are arranged below a model train 19 and directed at the spacers 12.

Sensing means 20 is fitted under a model train 19 on either a locomotive or one of several carriages (not shown) to which it is attached. Sensing means 20 comprises a transmitting means 22 and a receiving device 24. The sensing means 20 produces a linear output, the level of which depends on the reflective properties of the surface over which the model train 19 travels and the intensity of reflected signals received by the receiving device 24 which is a photo sensor or an infra-red detector 25.

As the train 19 moves along the track 11 the transmitting means 22, which is ideally a light emitting diode (LED) or a laser LED 23 generates a beam of radiation which is directed at the track 11 and spacers (sleepers) 12. Infra-red detector 25, operating as a receiving device 24, generates a signal S1 that is proportional to the intensity of the reflected signal that is detected when the radiation reflects off a spacer 12.

When the radiation reflects off a gap or ballast 13, the reflected infra-red signal that is detected by the infra-red detector 25 is at a different intensity and this generates a signal S2. Thus when viewing the plastic spacers 12, when compared with a gap between the spacers 14 (regardless of whether artificial ballast 13 is present) a different amount of reflected radiation is sensed. It will be understood that the greater the contrast between radiation reflected off the spacers 12, and that reflected from the ballast 15 (that is the gap between spacers), the greater is the difference between signals S1 and S2.

Processor unit 16 uses the signals S1 and S2 to distinguish between spacers 12 and non-spacers and produces a sequence of pulses: P1, P2, P3...PN at rate which is proportional to the speed of the train 19. The pulse sequence P1, P2, P3...PN is transmitted to either a digital or analogue filter 18. In one embodiment the characteristics of the optical sensing means 20 are dynamically adapted using the speed of the train, to further improve its immunity to errors by predetermining an expected mark-space ratio based on the speed of the train 19 and its acceleration or deceleration rate. The demand speed of a train 19 is therefore known because of existing signals being sent from the main controller 40.

Referring now to Figure 5 G1, G2, G3, G4 are digitally controlled gate limits. The positions of the gates are in terms of time related to the receipt of signals S1 and S2. Signal S1 and S2 are derived from radiation transmitted from the LED 23 and sensed by the IR detector 25. Together the LED 23 and IR detector 25 operate as a linear optical encoder 21. As the train 19 speeds up or slows down the pulse width 26 and pulse duration 27 decrease. Conversely the pulse width 26 and pulse duration 27 increase as train speed decreases.

Thus precise control of the limits of the digital filter is achieved. Thus the gates 32 and 34 only allow the correct pulses in the optical encoder 21 output to pass through the filter 18, as shown in Figure 5.

By employing the acceleration or deceleration of the train 19 to determine by how much a gate limit changes from one data transmission to a subsequent data transmission (from the encoder 21) accurate location information of the train 19 is therefore obtained.

Train speed may be used to control the parameters of filter 18 either by measuring actual speed derived from the output pulses of optical encoder 21 or a demand speed sent from the master controller 40. This also applies equally to the acceleration as well as the deceleration of the train 19.

The filter 18 may be an analogue based filter including a phase lock loop (PLL) or it may operate using other parameters that are controlled by the train speed and acceleration.

Reference is now made to Figures 4 and 6 which depict a section of railway that is operating as a transmission channel for an RF signal. Each railway line 10 displays both inductance and capacitance characteristics. The frequency of transmission is ideally around 400 MHz and is chosen in order to take advantage of inherent inductance and capacitance that is present between adjacent rails 10 and in order to 19 provide a transmission line which allows for an almost lossless transmission between the train 19 and the controller 40.

Ideally a model railway set includes a display wherein data relating to the train position and/or its speed are presented on the display in the form of information on a computer generated image. The display may be operative as a dashboard so that images and data and track layouts can be displayed via a mobile communication device.

It will be appreciated that variation may be made to the aforementioned embodiments without departing from the scope of the invention as defined in the appended claims. For example the invention may be included in a model railway set that includes the model train which is fitted with the system for determining its speed and location. Ideally the system for determining its speed and location of the train is provided in the form of a single device mounted in a chip, such as one that includes electronically erasable read only memory. For example I-phone (RTM) APP update software

For example, the invention may be used with a stair lift rail or other track and may be modified to count gaps in teeth in a rack and pinion type drive system.

Parts List rails track spacer or sleeper ballast processor unit filter train optical sensing means optical encoder

RF transmitter light emitting diode (LED) receiver infra-red detector pulse width pulse duration optical gate optical gate main controller counter

100 alternative speed sensor

102 unpowered vehicle

104 powered vehicle, such as a locomotive

106 means for providing a varying signal

108 wheel

109 wheel axle

110 Hall effect sensor

112 magnet

114 magnet

115 counter

116 timer

118 receiver

120 main or master controller

122 transmitter

Claims

1. A system for determining the position of a vehicle with at least one free running wheel comprising: a means mounted on the wheel for providing a varying signal in dependence upon the rotation of the wheel; a sensor which is mounted on the vehicle, senses the variation of the signal and generates pulses in response thereto; a counter counts the number of pulses in a time interval and a transmitter transmits the number of pulses to a remote receiver.

2. A system according to claim 1 includes at least a second means mounted on the wheel for providing a second signal which varies in dependence upon the rotation of the wheel.

3. A system according to claim 2 wherein the at least one second means is mounted on the wheel in a non-symmetric manner in order to provide a combined signal with the first signal which indicates the sense of rotation of the wheel and so enables the direction of travel to be derived.

4. A system according to any preceding claim wherein the means is mounted on one wheel or on an axle, which is decoupled from a second wheel.

5. A system according to any preceding claim wherein a counter counts the pulses and derives N (the number of turns of the wheel) and a processor determines distance travelled (D) using D = 2Ντγγ, where r is the radius of the wheel contacting the rail.

6. A system according to claim 5 includes a timer for deriving the speed of the vehicle from the distance travelled in a given timer interval.

7. A system according to any preceding claim includes a receiver that communicates the distance travelled and/or speed of the vehicle to a controller which includes a microprocessor for processing data received from one or more transmitters and a memory for storing data.

8. A system according to any preceding claim wherein the means mounted on the wheel includes at least one magnet.

9. A system according to claim 8 wherein the sensor includes: a Hall effect sensor and/or a reed switch sensor and/or a reluctance sensor and/or a proximity sensor, the sensor varies its output voltage in response to a varying magnetic field that is caused as the at least one magnet approaches and moves away from the sensor.

10. A system according to any preceding claim wherein the transmitter in the vehicle communicates with the remote receiver via a high frequency (HF) link.

11. A system according to claim 10 wherein communication is via the tracks over which the vehicle travels.

12. A system according to claim 11 wherein data is transmitted from the transmitter by modulating a high frequency signal across the tracks, via metal wheels on the vehicle by way of a means for generating a signal.

13. A system according to claim 12 wherein directional change of the vehicle is sensed by a change in voltage polarity across the tracks.

14. A system according to any preceding claim wherein the remote receiver provides data relating to one or more vehicles to a controller that operates in accordance with software for providing control signals for controlling at least the following: one or more peripheral devices; the position of at least one vehicle and/or the speed of at least one vehicle.

15. A system according to claim 14 wherein the vehicle is a train and peripheral devices include: points, barrier crossings, signal controls, lights and audio devices.

16. A system according to either claim 14 or 15 includes a display wherein data relating to the vehicle position and/or its speed are presented on the display in the form of information on a computer generated image.

17. A control system for a model railway network which includes a surface over which a toy train travels includes: display dashboard, speed software and input via a mobile communication device.

18. A toy carriage, truck or locomotive for a toy train, which moves over a surface includes: at least one magnet mounted on a wheel or an axle of a free running wheel; a magnetic sensor produces pulses from variations in a magnetic flux which occur as the axle or wheel rotates, the pulses are representative of rotation of the wheel over the surface; and a transmitter transmits the number of pulses sensed in a specified time interval to a remote receiver.

19. A toy carriage, truck or locomotive for a toy train according to claim 18 included in a toy railway set with carriages, track, models, a transformer and a controller.

20. A system for determining the position and speed of a vehicle comprising: a source of electromagnetic radiation which is directed to a surface over which the vehicle travels; a sensor for sensing the presence and absence of reflected radiation; and a control means that switches the sensor to an active mode for a duration that is dependent upon the speed of the vehicle, whereby in use a signal indicative of distance travelled by the vehicle is transmitted to a controller.

21. A system according to claim 20 includes a processor and a memory which is calibrated to the distance between spacers so that absolute location of the vehicle is determined from a datum by deriving the position travelled from the datum and multiplying a pulse count by the distance between adjacent rail spacers or sleepers.

22. A system according to claim 20 or 21 wherein a discriminator is provided in order to reject false signals and to place the sensor (or processing logic) into a state of readiness in order to anticipate the arrival of a true reflected pulse.

23. A system according to claim 20 or 21 wherein a filter is used to improve discrimination of the sensor and so provide immunity to false pulses.

24. A system according to claim 23 wherein the filter is controlled with knowledge of the speed and acceleration (or deceleration) thereby anticipating the arrival of detected pulses and rejecting detected false pulses.

25. A system according to any of claims 20 to 24 wherein the electromagnetic radiation emitter is preferably an infra-red light emitting diode (LED).

26. A system according to claim 25 wherein the wavelength of electromagnetic of the infra-red (IR) LED lies between 700 and 1000 nanometres.

27. A system according to any of claims 20 to 26 wherein the source of electromagnetic radiation and sensor for sensing the presence and absence of reflected radiation are mounted on an underside of the vehicle, so as to be able to view rail connecting means (sleepers) as well as spaces between the rails.

28. A system according to claim 27 wherein the source of electromagnetic radiation emitter is arranged in front of the sensor.

29. A system according to claim 27 wherein the source of electromagnetic radiation emitter is arranged adjacent the sensor.

30. A system for transmitting the position of a vehicle moving on rails comprising: a means for generating a high frequency (HF) signal and a means for modulating a transmitted signal on rails or tracks so that the rails or tracks define a transmission line for information transmitted from the vehicle to a remote location.

31 .A method of recording the location of a vehicle having a free running wheel on rails comprising the steps of: placing the vehicle at a datum in a railway network; recording the datum; traversing the vehicle along the rails to a desired location; deriving the distance traversed by the vehicle; and recording an end location by transmitting a signal indicative of the distance traversed to a remote receiver.

32. A method for transmitting the position of a vehicle moving on rails comprising: the steps of generating a high frequency (HF) signal and transmitting an HF signal along the tracks such that information from the vehicle is transmitted to a remote location.

33. A method according to claim 32 wherein the information includes identity of the vehicle and the location of the vehicle.

34. A method according to claim 33 is used in combination with a master controller to operate and control two or more vehicles on a railway network.

35. A method according to claim 34 wherein the frequency of the HF signal is in excess of 100 MHz.

36. A method according to claim 34 or 35 includes the steps of: transmitting signals to a receiver mounted in the vehicle; and receiving a command signal from the master controller via a separate communication channel.

37. A model train fitted with the system according to any of claim 20 to 30.

38. A model railway set includes the model train of claim 37 and railway track and a controller.

39. A model railway set according to claim 38 wherein the controller is adapted to be connected to a plurality of peripheral devices, the controller receives a signal from the train, in accordance with the method of any of claims 31 to 36, the signal includes data relating to the train position and/or its speed, and the controller controls the peripheral devices.

40.A model railway set according to claim 39 wherein the peripheral devices include: points, barrier crossings, signal controls and signals all of which are addressable by the controller and in accordance with the method of any of claims 31 to 36.