JP3345346B2 - Estimation arithmetic unit for height of center of gravity of vehicle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to attitude control of an automobile. INDUSTRIAL APPLICABILITY The present invention is used for a device that automatically controls the attitude of a vehicle in a stable direction based on the behavior of a running vehicle such as yaw or roll. The present invention, for example, by automatically detecting and calculating that the vehicle may be in a skidding state while traveling, by automatically controlling the brake pressure of all or some wheels, the vehicle The present invention can be used for an automatic control device that recovers to a state in which a side slip is less likely to occur. The present invention relates to attitude control for automatically restoring a stable state when a vehicle reaches a behavior not intended by a driver due to a driving operation exceeding the characteristics of the vehicle, such as a large steering wheel operation during high-speed running.
INDUSTRIAL APPLICATION This invention is utilized for rollover prevention of commercial vehicles, such as a bus and a truck.

[0002]

2. Description of the Related Art Conventionally, electronic control devices for brakes and vehicle stability control devices (VSC, Vehicle Stability Control) have been used.
Etc. are known. ABS (Antilock Brake System) is a typical system for electronic control devices related to brakes.
It is. This is to provide a rotation sensor on the wheel to detect the wheel rotation, and when the wheel rotation stops when the brake pressure is large, assuming that there was a slip between the wheel and the road surface,
The brake pressure is intermittently controlled. ABS has become widespread in passenger cars and freight cars, and has become widely known as a device that can handle while braking. As a typical device of the vehicle stabilization control device (VSC), a skid prevention device is known. This means that the course the driver is going to travel is read from the steering angle (steering angle) input by the driver, and if the vehicle speed is too high for that course, the driver will automatically enter without having to press the brake pedal. This is a device in which control for deceleration is performed and control such as distributing left and right brake pressures so as not to deviate from the course is performed.

[0003] A known vehicle attitude stabilizing device (VSC) (JP-A-63-279976, JP-A-2-112755, etc.) will be further described. When this is done, the direction of the vehicle changes and the vehicle rolls. At this time, when the tire of the inner wheel turning by steering exceeds the grip limit of the road surface, the inner wheel tends to be a so-called wheel lift, and the vehicle starts skidding. For example, when the driver steers to the left from a straight running state, the vehicle leans to the right. At this time, the vehicle turns in accordance with the steering in a normal state, but if the steering speed is too high relative to the traveling speed, the vehicle leans to the right and the left wheel is in a floating state, so that the driver Will move to the right from the intended direction. Such a behavior of the vehicle causes a deviation from the traveling lane or, in an extreme case, a rollover of the vehicle.

In a normal running state, the magnitude and speed of steering, the speed of the vehicle, the speed of lateral movement of the vehicle, and the speed of change in the direction of the vehicle (yaw rate, rotational acceleration of the vehicle around the vertical axis) are detected. A device has been developed which predicts the starting point of a skid of a wheel or the starting point of a wheel lift of an inner wheel by controlling the brake pressure of the wheel before the skid or the wheel lift starts. The brake pressure control of the wheels does not necessarily apply the same brake pressure to all the wheels, but applies a large or small brake pressure to one wheel to prevent the vehicle from skidding. Such an apparatus has been well studied not only for its basic structure and design, but also for its economy and durability, and has reached the stage of being mounted on a commercial product for a passenger car.

[0005] Such a conventional apparatus calculates a yaw rate from parameters relating to the current driving operation including steering and braking and parameters relating to the current behavior of the vehicle, that is, from the parameters at the current time. When it is determined that the yaw rate having the possibility of the sideslip that has been set and stored is reached, the brake pressure of the vehicle is automatically controlled. The possibility of this side slip is calculated by a transfer function from the vehicle operation data which is a driving operation input and various sensor outputs.

In the conventional transfer function calculation device, the calculation using the transfer function is a calculation method in which fast Fourier calculation is widely used. That is, the frequency of the operation input data and the behavior data is frequency-decomposed, and the response is approximated using a Fourier function. The fast Fourier operation has a convenient point such that a general-purpose analyzer that can be installed and used in a computer device can be easily obtained.

In such an apparatus for controlling the attitude of a vehicle, the position of the center of gravity of the vehicle is a very important parameter. The position of the center of gravity of a large commercial vehicle represented by a large truck changes depending on the state of the cargo. In the case of a bus, particularly in a route bus, the position of the center of gravity of the vehicle changes as passengers get on and off. Regarding the attitude control for preventing the rollover of the vehicle, the height of the center of gravity of the vehicle is an important parameter.

Conventionally, the center of gravity of a vehicle can be statically measured, but there is no method for measuring the center of gravity of a vehicle in real time in a running state. That is, while the vehicle whose center of gravity is to be measured is stopped on a horizontal road surface, the load distribution of each wheel is measured,
Next, the vehicle is moved to a road surface having a gradient in the front-rear direction and a road surface having a gradient in the left-right direction, and the load distribution of each wheel is measured, so that the position of the center of gravity including the height of the center of gravity is three-dimensionally measured. be able to.

A conventional attitude control device will be described with reference to FIGS. FIG. 5 is a diagram showing an example of the overall configuration of conventional attitude control. The vehicle 1 is a controlled object of the attitude control device. The vehicle 1 is provided with steering, braking, acceleration, and other driving operation inputs, and the response thereto is the behavior of the vehicle.
The vehicle 1 has an attitude control device 2 mounted thereon. The attitude control device 2 includes a vehicle stabilization control device (VSC) 3 and an electronic control braking device 4. The electronic control braking device 4 is a device represented by a conventional ABS means.

In order to observe the behavior of the vehicle as data, behavior data is output from sensors 11 mounted on the vehicle 1. The behavior data includes speed, lateral acceleration, yaw rate, roll rate, wheel rotation information, and others.

The vehicle stabilization control device 3 predicts and calculates the behavior of the vehicle using the driving operation input and the behavior data as input, and gives the result to the electronic control braking device 4. The electronically controlled braking device 4 also takes in driving operation input and behavior data, and additionally, a vehicle stabilization control device (VSC) 3
And outputs an automatic control output in a safe direction with respect to the driving operation input and the disturbance input to the vehicle 1, and this is a correction input.

FIG. 6 is a system configuration diagram of a conventional attitude control device. The control circuit 51 is an electronic device mounted on a vehicle including a computer circuit that is controlled by a program, and is a vehicle stabilization control device that receives a driving operation input of the vehicle and behavior data of the vehicle and calculates and outputs a motion state of the vehicle. (VSC) and control means for providing the vehicle with a correction input for correcting the driving operation input and the disturbance input to a safe side in accordance with the calculation output of the vehicle stabilization control device.

The vehicle is equipped with a yaw rate sensor 52, a lateral acceleration sensor 53, a roll rate sensor 60, and a longitudinal acceleration sensor 61. The detection outputs of these sensors are connected to a control circuit 51. Wheel rotation sensors 55 are attached to the front wheels 54f and the rear wheels 54r, respectively, and their detection outputs are also connected to the control circuit 51.
A brake pressure sensor 57 is attached to the brake booster actuator 56, and its detection output is also connected to the control circuit 51. A steering angle sensor 59 is attached to the steering handle 58, and the output is connected to the control circuit 51. A governor sensor 63 is incorporated in the governor 62 that controls the internal combustion engine, detects the state of the governor 62, and outputs the detection output to the control circuit 51. FIG. 7 is a perspective view showing an example of mounting each sensor on a vehicle. FIGS. 6 and 7 show a vehicle having a two-axis structure, but in the case of a large vehicle, a three-axis or four-axis structure is used.

[0014]

However, in the fast Fourier calculation conventionally used in the transfer function calculation, (1) a long time data is required for a signal with a low frequency, and (2) the number of data. Is a power of 2 (8, 16, 32, 64
..), An appropriate number of data may not be obtained in some cases, and (3) a closed loop in which feedback control is performed cannot be operated. In particular, in commercial vehicles such as trucks and buses, there is a component having a vibration frequency of about 1/100 Hertz in the behavior data, and such behavior data is used to calculate a transfer function by fast Fourier computation. Requires real-time data over 200 seconds, at least twice that period. In this case, it is not possible to obtain a practical device for performing calculations in real time during traveling. This is a serious problem that hinders the realization of a commercial vehicle attitude control device.

In a large vehicle, depending on the state of the cargo,
Alternatively, the physical characteristics of the vehicle greatly vary depending on the number of passengers and the seating position. That is, in the case of a passenger car, even if the number of passengers varies, the weight of the passenger (for example, 50 kg per person) is equal to the total weight of the vehicle (for example, 2000 kg).
And the crew is small. Moreover, since the boarding position of the passenger is fixed at a position with a low center of gravity,
Even when the number of passengers fluctuates, even if the calculation is performed with the vehicle model holding the physical constants of the vehicle fixed, the calculation result of the attitude control device does not have a large effect. However, in the case of a heavy-duty vehicle, in the case of a freight vehicle, the weight of the entire vehicle and the position of the center of gravity greatly change between a case where there is no load and a case where there is a typical load close to the loadable limit. Therefore, since the physical characteristics of the vehicle greatly change, even if the calculation is performed using a fixed vehicle model, it does not become a realistic value.

Further, in a truck, the load is not always loaded in a constant state, and the weight and the position of the load or the position of the center of gravity change each time. Even in the case of a large bus, the number of passengers varies from zero to about 50 people, and the position of the passengers in the vehicle also changes each time. In the case of a regular bus, it will change for each stop. Therefore, if the vehicle model on which the attitude control is based is fixedly set, practical attitude control cannot be performed. In order to solve this problem, the present applicant has proposed a vehicle attitude control device according to Japanese Patent Application No. 9-131347 (not disclosed at the time of filing the present application). However, this prior application does not mention the height of the center of gravity.

Here, considering the height of the center of gravity, there is conventionally a method of static measurement described in JIS security standards or the like, and the height of the center of gravity of a running vehicle is determined in real time. It could not be measured.

FIG. 8 shows a method for statically measuring the height of the center of gravity. As a method of statically measuring the height of the center of gravity, there is a method of FIG. 8 described in JIS security standards and the like, and the total body weight W, the weight Wf applied to the front wheels, the wheel base L, and the distance from the center of gravity to the rear wheels are measured. The distance Lr and the inclination angle α are measured, and the height hs of the center of gravity is calculated as hs = (W · Lr−Wf · L) / Wtanα (1).

That is, in the conventional measuring method, it is not possible to use the current data on the change in the center of gravity of the vehicle. In particular, in a freight vehicle in which the weight and the appearance of a load change, the center of gravity of the vehicle cannot be measured each time the load is unloaded, and the attitude control is performed using the approximate value.

In particular, since the height of the center of gravity varies depending on the cargo style of the cargo, for example, the height of the center of gravity measured at the time of departure for delivery changes when the cargo is unloaded to the customer. It cannot be used as control device data. Therefore, a technology that can measure the height of the center of gravity in real time while traveling is required.

The present invention has been made in such a background, and an object of the present invention is to provide an attitude control device suitable for a large vehicle, particularly a commercial vehicle. An object of the present invention is to provide a posture control device for adapting to a large vehicle in which behavior data includes many low frequency components. The present invention
An object of the present invention is to provide a posture control device for adapting to a vehicle in which the state of a load or a passenger changes. An object of the present invention is to provide a posture control device in which a vehicle model automatically follows a change in the state of a load or a passenger. An object of the present invention is to prevent a large vehicle from deviating from a traveling lane and to prevent rollover by driving control that exceeds the characteristics of the vehicle. An object of the present invention is to provide a device that can estimate the height of the center of gravity of a vehicle in real time. An object of the present invention is to improve control accuracy of a vehicle attitude control device.

[0022]

According to the present invention, the height of the center of gravity is determined in real time. The inventors paid attention to the method using the above-described formula (1), and attached an axle meter for measuring the weight applied to the axle and a gradient sensor for measuring the inclination with respect to the traveling direction to the vehicle. By measuring the weight Wf applied to the front axle with an axle meter and measuring the inclination angle α with a gradient sensor, even when the vehicle is in operation, the equation (1)
Was used to measure the height of the center of gravity.
Thereby, it is possible to estimate the height of the center of gravity that changes according to the package during the operation of the vehicle.

That is, the present invention relates to an apparatus for estimating the height of the center of gravity of a vehicle, comprising: means for measuring an inclination angle α along a traveling direction of the vehicle; means for measuring a weight Wf applied to a front shaft;
Means for measuring the weight Wr applied to the rear shaft, and the height hs of the center of gravity from both shaft heights is hs = (W · Lr−Wf · L) / Wtanα, where L is the wheelbase, and the distance from the front shaft to the center of gravity. Lf, a distance Lr from the position of the center of gravity to the rear axis Lr W = Wf + Wr (variable), L = Lf + Lr (constant), and means for calculating whenever the vehicle speed becomes zero and the inclination angle α exceeds a predetermined value. The height of the center of gravity hs
And means for calculating, updating and holding.

The distance Lr from the position of the center of gravity to the rear axis may be calculated as a constant set in advance, or the distance Lr from the position of the center of gravity to the rear axis may be calculated.
May include means for calculating from the weight Wf applied to the front shaft and the weight Wr applied to the rear shaft. The method of treating the distance Lr as a constant is suitable for use in a type of vehicle in which the position of the center of gravity does not change frequently. For example, it is suitable for the case where the shape of the cargo to be loaded is constant and its loading position is also constant, but only the weight changes. In such a case, by treating the distance Lr as a constant, the procedure for calculating the change in the center of gravity can be omitted, so that the speed of calculating the height of the center of gravity can be increased. Further, the method of calculating the distance Lr each time is suitable for use in a vehicle of a type in which the position of the center of gravity frequently changes. For example, when the shape of the cargo to be loaded and the loading position are not constant and change each time, the position of the center of gravity also changes frequently, so the distance Lr may be calculated each time.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a flowchart showing a measurement procedure according to the embodiment of the present invention. FIG. 2 is a system configuration diagram of the attitude control device according to the embodiment of the present invention. FIG. 3 is a perspective view showing an example of mounting each sensor of the embodiment of the present invention on a vehicle.

The present invention is an apparatus for estimating the height of the center of gravity of a vehicle, and as shown in FIGS. 2 and 3, a gradient sensor 65 which is means for measuring an inclination angle α along the traveling direction of the vehicle,
Axle load meter 64 which is a means for measuring the weight Wf applied to the front shaft
f, and an axle load meter 64r as a means for measuring the weight Wr applied to the rear shaft. The control circuit 51 determines the height of the center of gravity hs from the height of both shafts as hs = (W · Lr−Wf · L) / Wtanα where W is the wheelbase, L is the distance from the front axis to the center of gravity, Lr is the distance from the center of gravity to the rear axis, Lr is W = Wf + Wr (variable), and L = Lf + Lr (constant). Every time the vehicle speed becomes zero and the inclination angle α exceeds a predetermined value, the height of the center of gravity h
s is calculated and updated and held.

The case where the distance Lr from the position of the center of gravity to the rear axis is treated as a constant set in advance,
The distance Lr from the position of the center of gravity to the rear axis may be calculated from the weight Wf applied to the front axis and the weight Wr applied to the rear axis.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As a feature of a large vehicle, two axes, three
Since the vehicle is classified into an axle and an axle, and various types of wheelbases are present, the vehicle has different motion characteristics. FIG. 4 is a diagram showing the motion characteristics of the vehicle. The horizontal axis indicates frequency, and the vertical axis indicates gain and phase. When different wheelbases (WB (1) <WB (2) <WB (3)) of the same axle configuration are used, as shown in FIG. This indicates that the sensitivity is increased.

Also, when viewed from the way the vehicle is used, the axle load changes greatly when the vehicle is empty or loaded, and the center of gravity changes greatly depending on the type of packing. Therefore, it is important to grasp the position and height of the center of gravity as motion characteristics. is there.

The operation of the embodiment of the present invention will be described with reference to FIG. Equation (1) used in the present invention is originally for statically measuring the height of the center of gravity, and therefore, the measurement is performed when the vehicle speedometer is at zero speed (V = 0). If the vehicle is traveling on a general road, the measurement may be performed when the vehicle stops at a traffic light or the like. When the speedometer is at zero speed (V = 0) (S1),
The data from the gradient sensor 65 and the axle meters 64f and 64r are fetched (S2). The inclination angle α of the inclination sensor 65
Indicates zero or within ± 1 degree (S
3) The total weight W of the vehicle is measured (S6).

The total weight W of the vehicle body is obtained by adding the weight Wf applied to the front shaft and the weight Wr applied to the rear shaft. Theoretically, even when the vehicle body is greatly inclined, the total vehicle weight W can be obtained by adding the weight Wf applied to the front shaft and the weight Wr applied to the rear shaft. However, the axle meters 64f and 64r are designed so that the axle load can be accurately measured in a nearly horizontal state.
The total weight W of the vehicle body is measured within a range of zero inclination or ± 1 degree.

When the inclination angle α of the inclination sensor 65 is the most inclined at ± 1 ° or more (S4), the weight Wf applied to the front wheels
Is measured (S5). As a result, parameters necessary for calculating the height of the center of gravity, ie, the total weight W of the vehicle body, the weight Wf applied to the front wheels, and the inclination angle α are obtained, and the height of the center of gravity can be calculated (S7).

More specifically, the inclination angle α of the gradient sensor 65 is determined by waiting for a signal on a flat road surface or temporarily stopping.
While the vehicle is stopped within the range of zero or ± 1 degrees, the total weight W of the vehicle body is measured. After that, the inclination angle α of the gradient sensor 65 becomes ±
While the vehicle is stopped at least once, the weight Wf applied to the front wheels is measured. Thus, the height of the center of gravity can be calculated at any time during the operation of the vehicle.

There are a method of treating the distance Lr from the position of the center of gravity to the rear axis as being constant, and a method of calculating the distance Lr each time. As described above, the method of treating the distance Lr as a constant is suitable for use in a type of vehicle whose center of gravity does not frequently change. For example, it is suitable for the case where the shape of the cargo to be loaded is constant and its loading position is also constant, but only the weight changes. In such a case,
By treating the distance Lr as a constant, the procedure for calculating the change in the position of the center of gravity can be omitted, and the calculation speed of the height of the center of gravity can be increased. Further, the method of calculating the distance Lr each time is suitable for use in a type of vehicle in which the position of the center of gravity frequently changes. For example, when the shape of the cargo to be loaded and the loading position are not constant and change each time, the position of the center of gravity also changes frequently, so the distance Lr may be calculated each time.

A very simple example of a method of calculating the distance Lr each time is as follows: Wf / (Wf + Wr) = k · Lr / (Lf + Lr) Here, since k is a constant, Lr = (1 / k) · (Lf + Lr) · [Wf / (Wf +
Wr)].

[0036]

As described above, according to the present invention,
An attitude control device suitable for a large vehicle, particularly a commercial vehicle, can be realized. It is possible to realize a posture control device for adapting to a large vehicle in which behavior data includes many low frequency components. An attitude control device for adapting to a vehicle in which the state of a load or a passenger changes can be realized. Even if the state of the cargo or the passenger changes, it is possible to realize a posture control device in which the vehicle model automatically follows. It is possible to prevent a large vehicle from deviating from the traveling lane and to prevent rollover by driving control that exceeds the characteristics of the vehicle. The height of the center of gravity of the vehicle can be estimated in real time. The control accuracy of the vehicle attitude control device can be improved.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a measurement procedure according to an embodiment of the present invention.

FIG. 2 is a system configuration diagram of the attitude control device according to the embodiment of the present invention.

FIG. 3 is a perspective view showing an example of mounting each sensor of the embodiment of the present invention on a vehicle.

FIG. 4 is a diagram showing the motion characteristics of the vehicle.

FIG. 5 is a diagram showing an example of the overall configuration of a conventional attitude control.

FIG. 6 is a system configuration diagram of a conventional attitude control device.

FIG. 7 is a perspective view showing an example of mounting each sensor on a vehicle.

FIG. 8 is a diagram showing a method of statically measuring the height of the center of gravity.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vehicle 2 Attitude control device 3 Vehicle stabilization control device (VSC) 4 Electronic control braking device (EBS) 5 Observer 6 Numerical model 7 Calculation means 8 Evaluation means 9 Control amount calculation means 11 Sensors 41 Safety automatic control means 42 ABS calculation Means 51 Control circuit 52 Yaw rate sensor 53 Lateral acceleration sensor 54f Front wheel 54r Rear wheel 55 Wheel rotation sensor 56 Brake booster actuator 57 Brake pressure sensor 58 Steering handle 59 Steering angle sensor 60 Roll rate sensor 61 Forward / backward acceleration sensor 62 Governor 63 Governor sensor 64f, 64r Axle weight meter 65 Gradient sensor

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI G01G 19/08 G01G 19/08 Z // B62D 101: 00 B62D 101: 00 103: 00 103: 00 105: 00 105: 00 109 : 00 109: 00 111: 00 111: 00 113: 00 113: 00 131: 00 131: 00 137: 00 137: 00 (58) Field surveyed (Int.Cl. ⁷ , DB name) G01M 1/12 B60T 8/24 B60T 8/58 B62D 6/00 G01B 21/22 G01G 19/08 B62D 101: 00

Claims (3)

(57) [Claims] 1. A means for measuring an inclination angle α along a traveling direction of a vehicle, a means for measuring a weight Wf applied to a front shaft,
Means for measuring the weight Wr applied to the rear shaft, and the height hs of the center of gravity from both shaft heights is hs = (W · Lr−Wf · L) / Wtanα, where L is the wheelbase, and the distance from the front shaft to the center of gravity. Lf, a distance Lr from the position of the center of gravity to the rear axis Lr W = Wf + Wr (variable), L = Lf + Lr (constant), and means for calculating whenever the vehicle speed becomes zero and the inclination angle α exceeds a predetermined value. The height of the center of gravity hs
Means for calculating and updating and maintaining the height of the center of gravity of the vehicle. 2. The apparatus according to claim 1, wherein the distance Lr from the position of the center of gravity to the rear axis is preset as a constant. 3. A distance Lr from the position of the center of gravity to a rear axis.
2. The apparatus for estimating the height of the center of gravity of a vehicle according to claim 1, further comprising means for calculating from a weight Wf applied to the front shaft and a weight Wr applied to the rear shaft.