JP2004224262A - Automatic brake controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To apply a device for automatically performing brake control according to an output of a sensor such as an antecedent vehicle detecting device mounted to the vehicle to a freight vehicle where a control response characteristic varies according to a state of cargo. <P>SOLUTION: A control parameter such as deceleration coefficient for brake control is automatically made suitable according to the height of the center of gravity and other state of the freight vehicle. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an improvement in a device that automatically performs brake control without a driving operation in accordance with vehicle speed information, distance information from a preceding vehicle, and other sensor output information that detects a traveling state of a vehicle. The present invention is an apparatus developed for use in a lorry in which the position of the center of gravity of the vehicle or the like greatly changes depending on the state of the loaded cargo, but the gross weight and the position of the center of gravity are not limited to the lorry but depending on the mode of operation. It can be widely implemented for vehicles that vary greatly.
[0002]
[Prior art]
Automatic brake control device that measures the distance to the preceding vehicle or detects obstacles on the road surface and automatically controls the brakes without any driving operation based on the reflected wave sensor output of the radar device mounted on the vehicle It has been known. This device is configured such that a program control circuit is mounted on a vehicle, and a brake pressure that is arithmetically controlled based on vehicle speed information and vehicle state information obtained from a sensor output is supplied to a wheel brake device.
[0003]
As a device for improving such a device, Patent Literature 1 (Applicant, Toyota) discloses a technology for detecting a state of a traveling road surface and adjusting the brake pressure when automatically controlling a large brake pressure. It has been disclosed. Further, Patent Document 2 (Applicant, Toyota) discloses that when a driver is strongly depressing a brake pedal and is in an emergency braking state, a brake is automatically and auxiliary executed in accordance with a sensor output to prevent a collision. A control technique for avoidance is described. Patent Document 3 (Applicant, Nissan Diesel) also discloses a technique for reducing the braking distance by harmonizing a brake operation by a driving operation and an automatic brake control by a sensor output.
[0004]
[Patent Document 1]
JP-A-7-173467 [Patent Document 2]
JP-A-8-343268 [Patent Document 3]
JP-A-8-91190 [0005]
[Problems to be solved by the invention]
The inventors of the present application have conducted a test study on applying a device that automatically performs brake control to a commercial vehicle in accordance with a sensor output from an inter-vehicle distance detection device or an obstacle detection device on a traveling road surface. Among them, it was recognized that the response to the brake control differs greatly depending on the condition of the cargo truck. In other words, even if a brake control device is designed based on the same concept as a general vehicle such as a passenger car, the behavior of the vehicle when the brake is activated varies depending on the state of the cargo, and the brake may work too much. It turns out that there are no cases. Furthermore, the inventors have studied in detail how to recognize the state of the load and use it as a control parameter, and which element should be used to perform brake control.
[0006]
The present invention has been made in such a background, and provides an apparatus for automatically performing brake control according to a sensor output provided in a vehicle, which apparatus can be applied to a cargo vehicle. With the goal. SUMMARY OF THE INVENTION It is an object of the present invention to provide an automatic brake control device that works effectively even when the form of a load or a load changes greatly.
[0007]
[Means for Solving the Problems]
The present invention applies a device for automatically performing brake control to a commercial vehicle according to a sensor output from an inter-vehicle distance detection device or an obstacle detection device on a traveling road surface. It is characterized in that the control parameters are automatically made appropriate. This makes it possible to realize an automatic brake control device that works effectively even when the form of the load or the load changes greatly.
[0008]
That is, the present invention is an automatic brake control device including a control circuit that automatically performs a brake control without a driving operation based on a sensor output that detects a traveling state of a vehicle including a vehicle speed, and is a feature of the present invention. However, the control circuit includes means for changing a deceleration coefficient of the vehicle by the brake control using vehicle state information including information on a loaded state as input information.
[0009]
Here, the deceleration coefficient is a time differential value of the deceleration (negative acceleration). The smaller this value is, the slower the deceleration is, and the brake is operated with a margin from a distance relatively far from the target stop position. I do. Conversely, the larger the deceleration coefficient, the faster the deceleration is performed, and the brake is operated from a distance relatively close to the target stop position.
[0010]
The sensor output includes information on an inter-vehicle distance from a preceding vehicle measured by a radar device, and the control circuit automatically performs a brake control so that the inter-vehicle distance does not fall below a set value corresponding to the vehicle speed. It is desirable to include means.
[0011]
The information on the loading state includes, for example, information on the height of the center of gravity of the vehicle including the load and / or the weight distribution of each wheel of the vehicle.
[0012]
That is, according to the information on the height of the center of gravity of the vehicle including the load, it is possible to estimate the inclination of the vehicle due to braking at the cornering at the time of loading. Thereby, the bias of the load applied to each wheel can be estimated. It is desired that the greater the deviation of the load applied to the left and right wheels, the less sudden braking is performed. Therefore, based on the information of the height of the center of gravity of the vehicle including the cargo, for example, the higher the height of the center of gravity, the smaller the deceleration coefficient is changed, so that the safety in maintaining the vehicle posture during braking can be enhanced.
[0013]
Further, according to the information on the weight distribution of each wheel of the vehicle, it is possible to estimate the load applied to the front and rear wheels or the left and right wheels at the time of loading. It is desirable that the greater the deviation of the load applied to the front and rear wheels or the left and right wheels, the greater the need to avoid sudden braking. Therefore, based on the information on the weight distribution in the front-rear direction or the left-right direction of the vehicle including the load, for example, by changing the deceleration coefficient to a smaller value as the weight distribution is biased forward or backward, or rightward or leftward, Safety can be improved.
[0014]
The sensor output includes, for example, one or more of information on brake air pressure, information on brake temperature, and information on tire air pressure.
[0015]
That is, when the brake air pressure is low, when the brake temperature is high, or when the tire air pressure is low, the braking capacity is also low. Therefore, based on the information of the brake air pressure, the information of the brake temperature, and the information of the tire air pressure, the lower the braking ability, the smaller the deceleration coefficient is changed, thereby improving the safety of braking. Can be.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
A brake control device according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a configuration diagram of the vehicle of the present embodiment. FIG. 2 is a block diagram of the control circuit of this embodiment. FIG. 3 is a flowchart showing the operation of the brake control device of the present embodiment. FIG. 4 is a diagram showing the deceleration coefficient for each parameter. The horizontal axis represents each parameter, and the vertical axis represents the deceleration coefficient.
[0017]
In the present embodiment, as shown in FIG. 1, a speedometer (not shown) which is a sensor for detecting a running state of a vehicle including a vehicle speed, an accelerometer 2, a radar device 3, a brake system information collecting unit 4, an axle load meter 7 is an automatic brake control device provided with a control circuit 1 for automatically performing a brake control without a driving operation by the output of the control circuit 7. The feature of this embodiment is that the control circuit 1 As shown in FIG. 2, the deceleration coefficient setting unit 8 that changes the deceleration coefficient of the vehicle by the brake control is used as input information including the vehicle state information.
[0018]
The sensor output includes information on the following distance measured by the radar device 3 with respect to the preceding vehicle, and the control circuit 1 automatically controls the brake so that the following distance does not fall below a set value corresponding to the vehicle speed. The distance control unit 9 performs the following. The inter-vehicle distance control unit 9 gives an instruction to the automatic brake operation unit 10 and automatically performs the brake control so that the inter-vehicle distance from the preceding vehicle does not fall below a set value for the vehicle speed.
[0019]
The information on the loading state includes information on the height of the center of gravity of the vehicle including the load and / or the weight distribution of each wheel of the vehicle. It is appropriate that such information is obtained as input information from the data input unit 5 by a driver or a cargo handler. That is, a means is provided for setting the state of the cargo to any of "high", "medium", and "low" by using several stages of operation switches, and the state of the operation switches becomes input information. In addition, information on the height of the center of gravity of the vehicle can be obtained by the accelerometer 2 and the axle meter 7 attached to the chassis.
[0020]
This will be described in detail. This method of calculating and estimating the height of the center of gravity of the vehicle has been previously proposed by the applicant as Patent Document 4. That is, from the inclination angle α detected by the accelerometer 2 along the traveling direction of the vehicle and the weight Wf applied to the front axis and the weight Wr applied to the rear axis detected by the axle meter 7, the height of the center of gravity hs is given by hs = ( W ・ Lr-Wf ・ L) Wtanα
Here, the wheelbase is calculated as L, the distance Lf from the front axis to the center of gravity, the distance Lr from the center of gravity to the rear axis is calculated as W = Wf + Wr (variable), and L = Lf + Lr (constant).
[0021]
[Patent Document 4]
Patent No. 3345346
Other methods for calculating the height of the center of gravity of the vehicle include a transfer function of a dynamic model having a degree of freedom including roll with respect to the steering angle, and a vehicle speed, roll rate, and steering angle data collected from various sensors using an autoregressive method. A method of calculating the height of the center of gravity from the transfer function for the required steering angle and the like (Patent Document 5) can be applied.
[0023]
[Patent Document 5]
Japanese Patent No. 3369467
Thus, the deceleration coefficient setting unit 8 of the control circuit 1 can estimate the height of the center of gravity of the vehicle. In addition, it is possible to estimate the bias of the load on each wheel from the sensor output of the axle meter 7. In addition, the output of the brake system information collection unit 4 includes at least one of the information on the brake air pressure, the information on the brake temperature, and the information on the tire air pressure, so that the level of the braking capacity can be estimated.
[0025]
If the driver or the cargo handler does not input the information from the data input unit 5 or forgets it, the necessary information is automatically obtained only from the sensor output from the accelerometer 2 or the axle meter 7. Can be configured. Further, the error of the input information from the data input unit 5 can be automatically corrected based on the sensor output from the accelerometer 2 or the axle meter 7.
[0026]
Next, a control operation of the brake control device according to the present embodiment will be described. This is executed by software set in the control circuit 1. As shown in FIG. 3, the deceleration coefficient setting unit 8 includes loading status information from the data input unit 5 or the accelerometer 2 and the axle meter 7, vehicle speed information from the speedometer, and brake system information from the brake system information collection unit 4. Then, inter-vehicle distance information is collected by the radar device 3 (step 1), and a deceleration coefficient is set for each parameter (step 2). The setting of the deceleration coefficient for each parameter is performed according to the control map shown in FIG. This control map is recorded in the deceleration coefficient setting unit 8 in advance.
[0027]
The control map of FIG. 4A shows the relationship between the height of the center of gravity and the deceleration coefficient. In other words, slower deceleration is required when the load is heavy compared to when the load is flat. The control map of FIG. 4B shows the relationship between the load bias and the deceleration coefficient. That is, when the load is unbalanced, slower deceleration is required compared to when the load is uniform. The control map of FIG. 4C shows the relationship between the air pressure of the air tank 6 and the deceleration coefficient. That is, when the air pressure is low, the braking ability is lower than when the air pressure is high, and slow deceleration is required. The control map of FIG. 4D shows the relationship between the brake temperature and the deceleration coefficient. That is, when the brake temperature is high, the braking capacity is lower than when the brake temperature is low, and slow deceleration is required. The control map of FIG. 4E shows the relationship between the tire air pressure and the deceleration coefficient. That is, when the air pressure is low, the gripping ability is lower than when the air pressure is high, and slow deceleration is required.
[0028]
When the setting is performed for all the parameters (step 3), a general deceleration coefficient is set (step 4). Here, the general deceleration coefficient is a deceleration coefficient obtained by combining the deceleration coefficients for each parameter shown in FIG. 4 in a complex manner. For example, if the state of heavy load shown in FIG. 4A is the state of post-load shown in FIG. 4B, the deceleration coefficient obtained by combining the state of high load and the state of post-load is combined. Must be set. Assuming that the deceleration coefficient in the high load state is 0.8 and the deceleration coefficient in the rear load state is 0.9, the reciprocal of 1.7 which is a value obtained by adding 0.9 to 0.8. 0.6 is the deceleration coefficient in this state. As a result, a deceleration coefficient obtained by compounding the deceleration coefficients for each parameter is set.
[0029]
In addition, when a large number of deceleration coefficients set according to the control maps shown in FIGS. 4A to 4E are combined, the deceleration coefficient becomes small enough to cause trouble in normal running. Then, an alarm indicating that fact is issued to urge the driver or the cargo handler to load the cargo or to improve the load (steps 5 and 6).
[0030]
In this way, a complex deceleration coefficient is set. If the vehicle is running (step 7), the distance from the preceding vehicle is measured (step 8), and if the measurement result is equal to or less than the set distance (step 8). Step 9), braking is performed based on the set deceleration coefficient (step 10). In addition, as for the set distance from the preceding vehicle, a safe inter-vehicle distance is set in advance in the inter-vehicle distance control unit 9 according to the vehicle speed, and the inter-vehicle distance control unit 9 calculates the pre-set inter-vehicle distance, deceleration coefficient, A predetermined braking operation is instructed to the automatic brake operation unit 10 based on the command.
[0031]
The information collection in step 1 can estimate the height of the center of gravity using the accelerometer 2 and the axle meter 7 while the vehicle is running. Further, even when the vehicle is stopped, the height of the center of gravity can be estimated using the input information from the data input unit 5.
[0032]
【The invention's effect】
As described above, according to the present invention, a device that automatically performs brake control according to a sensor output provided in a vehicle can be applied to a freight vehicle. In addition, even if the form of the load or the load changes greatly, an automatic brake control device that works effectively can be realized.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a vehicle according to an embodiment.
FIG. 2 is a block diagram of a control circuit according to the embodiment.
FIG. 3 is a flowchart showing the operation of the brake control device according to the embodiment.
FIG. 4 is a diagram showing a deceleration coefficient for each parameter.
[Explanation of symbols]
Reference Signs List 1 control circuit 2 accelerometer 3 radar device 4 brake system information collecting unit 5 data input unit 6 air tank 7 axle load meter 8 deceleration coefficient setting unit 9 inter-vehicle distance control unit 10 automatic brake operation unit

Claims (4)

An automatic brake control device including a control circuit that automatically performs brake control without a driving operation based on a sensor output that detects a traveling state of a vehicle including a vehicle speed,
The automatic brake control device according to claim 1, wherein the control circuit includes a unit that changes a deceleration coefficient of the vehicle by the brake control using, as input information, vehicle state information including information on a loaded state. The sensor output includes information on an inter-vehicle distance from a preceding vehicle measured by a radar device, and the control circuit automatically performs brake control so that the inter-vehicle distance does not fall below a set value corresponding to the vehicle speed. 2. The automatic brake control device according to claim 1, including means. 2. The automatic brake control device according to claim 1, wherein the information on the loaded state includes information on a height of a center of gravity of a vehicle including a load and / or a weight distribution of each wheel of the vehicle. 2. The automatic brake control device according to claim 1, wherein the sensor output includes at least one of information on a brake air pressure, information on a brake temperature, and information on a tire air pressure.

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