WO2018235929A1

WO2018235929A1 - Travel control device

Info

Publication number: WO2018235929A1
Application number: PCT/JP2018/023748
Authority: WO
Inventors: 陽介橋本
Original assignee: 株式会社アドヴィックス
Priority date: 2017-06-23
Filing date: 2018-06-22
Publication date: 2018-12-27
Also published as: JP2019006253A

Abstract

A travel control device that controls, for example, the travel of a vehicle for which at least a rear wheel is a drive wheel. The travel control device comprises: an operation amount calculation unit that calculates an operation amount for controlling a drive mechanism and/or a braking mechanism for the vehicle to reduce the deviation between a target location for the vehicle and the actual location of the vehicle; a determination unit that, on the basis of a detected value from a sensor that detects the rotation of the drive wheel, calculates the actual location and determines whether the drive wheel has slipped; and a target location setting unit that sets and resets the target location as time passes and, when the determination unit has determined that the drive wheel has slipped, does not update the target location until the determination unit has determined that the drive wheel is no longer slipping.

Description

Traveling control device

The present invention relates to a travel control device for a vehicle.

2. Description of the Related Art A travel control device is known that executes travel control that assists part or all of a driver's operation in a vehicle.

JP 2003-206780 A

In the conventional travel control device, for example, when the friction coefficient of the road surface is small due to the road surface condition and the wheels slip during execution of the travel control, the travel control is canceled. However, even if the wheels slip like that, it is preferable to continue stable travel control from the viewpoint of the driver.

Therefore, one of the problems of the present invention is, for example, to obtain a traveling control device capable of continuing stable traveling control even when the wheels slip during execution of traveling control.

The travel control device according to the present invention is, for example, a travel control device that controls the travel of a vehicle in which at least the rear wheels are drive wheels, and the drive mechanism of the vehicle reduces the deviation between the target position and the actual position of the vehicle. The drive wheel calculates the actual position based on a detection value from an operation amount calculation unit for calculating an operation amount for controlling at least one of the braking mechanism and a sensor, and a sensor for detecting the rotation of the drive wheel. The determination unit determines whether the vehicle has slipped, the target position is set while changing with the passage of time, and the determination unit determines that the drive wheel has slipped, the determination unit determines the drive. And a target position setting unit that stops updating of the target position until it is determined that the wheel slip has been eliminated. The determination unit, after determining that the drive wheel has slipped, calculates the actual position based on data other than the detection value from a sensor that detects the rotation of the drive wheel.

Further, in the travel control device, for example, in the vehicle, the front wheel is a rolling wheel (non-driving wheel), and the determination unit determines that the driving wheel has slipped, and then the rolling wheel (non-driving wheel) The actual position is calculated based on a detection value from a sensor that detects the rotation of the sensor.

Further, in the travel control device, for example, after the determination unit determines that the driving wheel has slipped, at least one of peripheral image data of the vehicle captured by the on-vehicle camera and a detection value from an acceleration sensor. The actual position is calculated based on

Further, in the travel control device, for example, the operation amount calculation unit may determine that the operation amount exceeds the operation amount when the drive wheel slips after the determination unit determines that the drive wheel has slipped. Calculate with no value.

FIG. 1 is a block diagram showing an example of a schematic configuration of a travel control device of the embodiment. Drawing 2 is a flow chart which shows an example of a procedure of control by a run control device of an embodiment. FIG. 3 is a diagram showing an example of change over time of parameters in the travel control device of the embodiment. FIG. 4 is a graph showing an example of the relationship between the slip amount and the driving force reduction amount in the travel control device of the embodiment.

In the following, exemplary embodiments of the present invention are disclosed. The configurations of the embodiments shown below, and the operations and results (effects) provided by the configurations are examples. The present invention can also be realized with configurations other than the configurations disclosed in the following embodiments. Further, according to the present invention, it is possible to obtain at least one of various effects (including derivative effects) obtained by the following configuration.

First, an example of a schematic configuration of a travel control device 100 according to an embodiment will be described with reference to FIG. FIG. 1 is a block diagram showing an example of a schematic configuration of a travel control device 100 of the embodiment. The travel control device 100 executes travel control that assists part or all of the operation by the driver in the vehicle 1 (FR vehicle) in which the rear wheels are drive wheels and the front wheels are rolling wheels (non-drive wheels). In addition, the travel control device 100 is stable even when the wheels have slipped due to the small coefficient of friction of the road surface due to the road surface condition (for example, the condition that there is water or snow on the road surface) during travel control. It is possible to continue traveling control (details will be described later).

The travel control device 100 controls at least one of the drive mechanism 201 and the braking mechanism 202 at the end point position, that is, in the control section to the final target position, whereby the acceleration and deceleration of the vehicle 1 are performed. Control at least one of them. The travel control device 100 can be configured, for example, as part of a parking assistance device, an automatic travel system, an automatic steering system, and the like. The drive mechanism 201 is, for example, an internal combustion engine or a motor, and includes an ECU (Electronic Control Unit) thereof. The braking mechanism 202 is, for example, a hydraulic braking system, and includes its ECU. In the following example, the travel control device 100 does not control steering, but may control steering. In the following, at least one of the drive mechanism 201 and the braking mechanism 202 may be simply referred to as a control target.

The traveling control device 100 controls the control target by control including feedback control. Feedback control is control that reduces the deviation between a target value and an actual value.

The traveling control device 100 includes a target value setting unit 10, a control unit 20, a determination unit 30, an actual value acquisition unit 40, and the like. The control unit 20 includes an operation amount calculation unit 21, a command value calculation unit 22, and the like.

The target value setting unit 10 sets the target position while changing with the passage of time, and when the judgment unit 30 judges that the drive wheel has slipped, the judgment unit 30 judges that the slip of the drive wheel has been eliminated. Stop updating the target position until it is done. This makes it possible to prevent the amount of control by feedback control or the like from becoming excessive. The following specifically describes the case of parking assistance as an example. In the case of parking assistance, the traveling control device 100 controls traveling from the start position of the vehicle 1 to the end position.

The target value setting unit 10 acquires data of the end point position. The data of the end point position is, for example, the moving distance of the vehicle 1 from the start point position to the end point position. In the travel control device 100, the temporal change of the position of the vehicle 1 is set so that the vehicle 1 moves from the start position to the end position of the control section. The target value setting unit 10 sets the target value of each parameter at each control timing, that is, each time, so that the change of the set position of the vehicle 1 over time is obtained in the control section from the start position to the end position. Do. The parameters are, for example, the position and speed of the vehicle 1. In the traveling control device 100, the distance from at least one of the start position and the end position of the control section may be set as the position of the vehicle 1. Further, the target value setting unit 10 may calculate the target value at each control timing, or may acquire the target value calculated and stored in advance at each control timing.

The actual value acquisition unit 40 acquires an actual value of the same parameter as the target value. That is, in the present embodiment, the actual value acquisition unit 40 acquires (estimates), for example, the actual value of the position of the vehicle 1 and the actual value of the speed of the vehicle 1. The actual value is a value obtained according to the operation of the control target, and is a detected value or a value derived from the detected value. For example, the actual value of the position and the actual value of the speed can be calculated from the detection values of the wheel speed sensor as the sensor 203. In the present embodiment, for example, it is assumed that the vehicle 1 includes four wheels, of which two wheels on the rear wheel are drive wheels and two wheels on the front wheel are rolling wheels (non-drive wheels). And the actual value of the position and the actual value of the speed are detected values of the wheel speed sensor of the driving wheel (hereinafter, also referred to as "wheel speed sensor value of the driving wheel") and detected values of the wheel speed sensor of the rolling wheel It can be calculated from any of (hereinafter, also referred to as “wheel speed sensor value of rolling wheels”).

The sensor 203 is, for example, a sensor that detects or acquires data such as a position, an attitude, a state, and a surrounding image when the vehicle 1 stops or travels, and may be other than the wheel speed sensor. For example, the sensor 203 may be an acceleration sensor or a device that outputs data such as a detection value based on peripheral image data of the vehicle 1 captured by an onboard camera. Further, the actual value acquisition unit 40 can acquire the detection results from the plurality of sensors 203.

The operation amount calculation unit 21 of the control unit 20 calculates an operation amount for the control target. The operation amount calculation unit 21 calculates an operation amount for controlling at least one of the drive mechanism 201 and the braking mechanism 202 of the vehicle 1 so as to reduce the deviation between the target position of the vehicle 1 and the actual position (actual value of position). Do. In addition, after the determination unit 30 determines that the drive wheel has slipped, the operation amount calculation unit 21 calculates the operation amount at a value that does not exceed the operation amount (drive force upper limit value) when the drive wheel slips. (Details will be described later).

The command value calculation unit 22 of the control unit 20 calculates a command value to the control target corresponding to the operation amount calculated by the operation amount calculation unit 21. For example, when the operation amount is a positive value, the command value calculation unit 22 sets a drive command value (control command value) to the drive mechanism 201 such that an acceleration corresponding to the magnitude of the operation amount is obtained. Calculate the rotational torque command value as In addition, for example, when the operation amount is a negative value, the command value calculation unit 22 gives a braking command value to the braking mechanism 202 so that deceleration corresponding to the magnitude of the operation amount, that is, negative acceleration can be obtained. A braking torque command value as a (control command value) is calculated. In addition, according to the traveling condition of the vehicle 1, for example, the command value calculation unit 22 accelerates the drive mechanism 201 while the vehicle 1 is braked by the braking mechanism 202, or while the vehicle 1 is propelled by the drive mechanism 201. The torque distribution between the drive mechanism 201 and the brake mechanism 202 can be determined so that a state of deceleration by the brake mechanism 202 can be obtained. In that case, the command value calculation unit 22 calculates command values to both the drive mechanism 201 and the braking mechanism 202 according to the distribution of the driving torque and the braking torque. The command value calculation unit 22 transmits a control command value to the control target, and the control target that has received the control command value executes control based on the control command value.

The determination unit 30 calculates the actual position based on the detection value (wheel speed sensor value of the drive wheel) from the sensor that detects the rotation of the drive wheel, and determines whether the drive wheel has slipped. Specifically, when determining whether or not the drive wheel slips, the determination unit 30 specifically includes the wheel speed sensor value of the rolling wheel and the value detected by the acceleration sensor in addition to the wheel speed sensor value of the drive wheel. When at least one of the slip rates exceeds a predetermined threshold, it is determined that the drive wheel has slipped. Further, after determining that the drive wheel has slipped, the determination unit 30 calculates the actual position based on data other than the detection value from the sensor that detects the rotation of the drive wheel. Specifically, after determining that the drive wheel has slipped, the determination unit 30 calculates the actual position based on a detection value (wheel speed sensor value of the rolling wheel) from a sensor that detects the rotation of the rolling wheel. .

Further, the determination unit 30 determines whether the actual value follows the target value. In the traveling control device 100, conditions for determining whether to follow or not are set. The determination unit 30 determines whether the actual value follows the target value by comparing the value of the predetermined parameter with the condition set for the parameter.

The traveling control device 100 is, for example, an ECU. The travel control device 100 may be incorporated in an ECU (for example, a brake ECU) of any system mounted on the vehicle 1 or may be an independent ECU. The travel control device 100 can have a central processing unit (CPU), a controller, a random access memory (RAM), a read only memory (ROM), a flash memory, and the like (not shown). The traveling control device 100 can execute processing according to the installed and loaded program to realize each function. In other words, the travel control device 100 executes the processing according to the program, and the travel control device 100 performs the target value setting unit 10, the control unit 20, the operation amount calculation unit 21, the command value calculation unit 22, the judgment unit 30, and the actual value acquisition unit 40. Etc can function. The storage unit stores data used in the arithmetic processing of each unit, data of the result of the arithmetic processing, and the like. Note that at least a part of the functions of the above-described units may be realized by hardware. In addition to feedback control, feedforward control or other control such as a so-called disturbance observer may be incorporated into the control by the traveling control device 100.

Next, with reference to FIG. 2, an example of a procedure of control by the traveling control device 100 will be described. FIG. 2 is a flowchart showing an example of the procedure of control by the traveling control device 100 of the embodiment. In the following, regarding the processing other than the characteristic processing of each of the units 10 to 40 in the traveling control device 100, the main subject of operation will be expressed as "the traveling control device 100." Further, at an arbitrary timing during the control of FIG. 2, the travel control device 100 ends the process when the driver performs an operation to end the parking assistance control, but the explanation thereof will be described below. I omit it.

In step S1, the traveling control apparatus 100 determines whether to start parking assistance control, and proceeds to step S2 in the case of Yes, and returns to step S1 in the case of No. For example, when there is an operation to start parking assistance control by the driver, the traveling control apparatus 100 determines Yes in step S1.

Next, in step S2, the traveling control device 100 executes parking assistance control. Specifically, the actual value acquisition unit 40 acquires the actual value of the position (distance) of the vehicle 1 and the actual value of the speed of the vehicle 1 based on the wheel speed sensor value of the drive wheel as the sensor 203 ( presume. Further, the target value setting unit 10 sets (updates) the target value of the position of the vehicle 1 and the target value of the speed of the vehicle 1 over time. Then, the operation amount calculation unit 21 calculates an operation amount for the control target. The command value calculation unit 22 calculates a control command value to the control target corresponding to the operation amount calculated by the operation amount calculation unit 21, and transmits the control command value to the control target. The control target that has received the control command value executes control based on the control command value.

Next, in step S3, the determination unit 30 determines whether or not the drive wheel has slipped (acceleration slip) using, for example, the wheel speed sensor value of the drive wheel and the wheel speed sensor value of the rolling wheel It is determined whether or not the predetermined threshold value is exceeded. If the determination is Yes, the process proceeds to step S4, and if the determination is No, the process returns to step S2.

Here, FIG. 3 is a figure which shows the example of a time-dependent change of the parameter in the traveling control apparatus 100 of embodiment. In FIG. 3, it is assumed that parking assistance control is started at time 0. FIG. 3 schematically shows how parameters change with time, and is not a strict graph.

As shown in the first graph from the top of FIG. 3, from time 0, the target value of the distance increases with the passage of time, and the actual value of the distance (the estimated distance based on the wheel speed sensor value of the driving wheel) is also It increases with the passage of time. Further, since the drive wheel of the vehicle 1 is not slipping from time 0 to time t1, the actual value of the distance and the true value (actual value) of the distance are substantially equal. Then, slippage of the drive wheels starts at time t1 (rolling wheels do not slip), and at time t2 the slip ratio of the drive wheels exceeds a predetermined threshold (“α” in the third graph from the top of FIG. 3) (Yes at step S3 in FIG. 2). Therefore, from time t1 to time t2, the actual value of the distance gradually deviates from the true value of the distance.

Also, as shown in the second graph from the top of FIG. 3, from time 0, the target value of the speed increases with the passage of time, and the actual value of the speed (estimated speed based on the wheel speed sensor value of the driving wheel ) Also increases with the passage of time. Further, since the drive wheel of the vehicle 1 is not slipping from time 0 to time t1, the actual value of the speed and the true value (actual value) of the speed are substantially equal. Then, from time t1 to time t2, the actual value of the velocity gradually deviates from the true value of the velocity.

Further, as shown in the third graph from the top of FIG. 3, from time 0 to time t1, the wheel speed sensor value of the drive wheel and the wheel speed sensor value of the rolling wheel are substantially equal. However, from time t1 to time t2, the wheel speed sensor value of the drive wheel gradually deviates from the wheel speed sensor value of the rolling wheel. In addition, it is preferable to use the wheel speed sensor value of the rolling wheel for estimation of the distance and the speed in that the rolling wheel does not slip (it is difficult to slip). However, in the case of an FR car, since the rolling wheels are front wheels that are steered wheels, estimation accuracy is reduced due to the influence of steering. Therefore, it is better to use the wheel speed sensor value of the drive wheel (rear wheel, non-steered wheel) in that the error at the time of turning operation of the vehicle 1 is small. And estimate the speed.

Also, as shown in the fourth graph from the top of FIG. 3, the driving force generated by the control target is increasing from time 0 to time t2.

Returning to FIG. 2, in step S4, the operation amount calculation unit 21 stores the driving force at time t2 in FIG. 3 as the driving force upper limit value D in the storage unit.

Next, in step S5, the target value setting unit 10 stops the calculation (update) of the target value of the distance and the target value of the speed. As a result, it is possible to prevent an excessive amount of control by subsequent feedback control or the like.

Next, in step S6, the traveling control device 100 executes the parking assistance control while reducing the driving force. Specifically, the actual value acquisition unit 40 acquires the actual value of the position (distance) of the vehicle 1 and the actual value of the velocity of the vehicle 1 based on the wheel speed sensor values of the rolling wheels, not the drive wheels ( presume. Then, the operation amount calculation unit 21 calculates the amount of operation on the control target so that the driving force is reduced.

Here, FIG. 4 is a graph showing an example of the relationship between the slip amount and the driving force reduction amount in the travel control device 100 of the embodiment. As shown in FIG. 4, the larger the slip amount, the larger the amount of decrease in the driving force. Such related information is stored in the storage unit. The operation amount calculation unit 21 calculates the next driving force (operation amount) by subtracting the driving force reduction amount proportional to the slip amount as shown in FIG. 4 from the previous driving force at each control timing. . Then, the command value calculation unit 22 calculates a control command value to the control target corresponding to the operation amount calculated by the operation amount calculation unit 21, and transmits the control command value to the control target. The control target that has received the control command value executes control based on the control command value.

Returning to FIG. 2, after step S6, in step S7, the determination unit 30 slips (acceleration slip) of the drive wheel using, for example, the wheel speed sensor value of the drive wheel and the wheel speed sensor value of the rolling wheel If the answer is yes, the process proceeds to step S8, and if the answer is no, the process returns to step S6.

Here, as shown in the first graph from the top of FIG. 3, the target value of the distance is constant from time t2 to time t3, and the actual value of the distance (estimated distance based on the wheel speed sensor value of the rolling wheels ) Increases with the passage of time as a value not affected by slip (a value close to the true value).

Also, as shown in the second graph from the top of FIG. 3, the target value of the speed is constant from time t2 to time t3, and the actual value of the speed (estimated speed based on the wheel speed sensor value of the rolling wheel) Increases over time as a value that is not affected by slip (a value close to the true value).

In addition, as shown in the third graph from the top of FIG. 3, the wheel speed sensor value of the drive wheel temporarily deviates from the wheel speed sensor value of the rolling wheel from time t2 to time t3. But then get close.

Further, as shown in the fourth graph from the top of FIG. 3, from time t2 to time t3, the driving force generated by the control target is reduced (decreased amount β).

Next, in step S8, the target value setting unit 10 resumes the calculation (update) of the target value of the distance and the target value of the speed.

Next, in step S9, the traveling control device 100 executes the parking assistance control while making the driving force not exceed the driving force upper limit value (the driving force upper limit value D in FIG. 3). Specifically, the actual value acquisition unit 40 acquires the actual value of the position (distance) of the vehicle 1 and the actual value of the velocity of the vehicle 1 based on the wheel speed sensor values of the drive wheels, not the rolling wheels ( presume. Further, the target value setting unit 10 sets (updates) the target value of the position of the vehicle 1 and the target value of the speed of the vehicle 1 over time. Then, the operation amount calculation unit 21 calculates the operation amount with respect to the control target so that the driving force does not exceed the driving force upper limit value (the driving force upper limit value D in FIG. 3). The command value calculation unit 22 calculates a control command value to the control target corresponding to the operation amount calculated by the operation amount calculation unit 21, and transmits the control command value to the control target. The control target that has received the control command value executes control based on the control command value. Thereafter, the traveling control device 100 repeats the process of step S9.

As described above, according to the travel control device 100 of the present embodiment, for example, stable travel control can be continued even when the wheels slip during execution of travel control. . That is, when the drive wheel of the vehicle 1 slips, the actual value of the distance or speed is estimated based on the wheel speed sensor value of the drive wheel so far, based on the wheel speed sensor value of the rolling wheel By switching so as to estimate, the error can be reduced.

Further, by stopping the updating of the target value of the distance and speed by the target value setting unit 10 until the driving wheel of the vehicle 1 slips and then cancels it, it is prevented that the control amount by feedback control etc. becomes excessive. Can.

In addition, after the driving wheels of the vehicle 1 slip, the vehicle 1 slips again by executing the parking assist control while preventing the driving force from exceeding the driving force upper limit value (the driving force upper limit value D in FIG. 3). The possibility of doing so can be reduced.

In addition, when the friction coefficient of the road surface is low and the vehicle slips, thereafter, in the prior art, the traveling control may not be stabilized, acceleration and deceleration may be repeated, and the riding comfort may deteriorate. The On the other hand, according to the present embodiment, even when the vehicle has slipped due to the low coefficient of friction of the road surface, the travel control is stable and unnecessary acceleration and deceleration are not repeated, so a comfortable ride condition is obtained. Can be maintained.

Next, a modification of the travel control device 100 according to the embodiment will be described. In the above embodiment, when the drive wheel of the vehicle 1 slips, the actual value of the distance and speed is estimated based on the wheel speed sensor value of the drive wheel so far, so the wheel speed sensor of the rolling wheel It switched to estimate based on the value, but instead, it switched to estimate based on at least one of the peripheral image data of the vehicle 1 captured by the on-vehicle camera and the detection value from the acceleration sensor Good. By doing so, the error of the actual value of the distance or speed can be suppressed to be small as well.

The vehicle 1 may be a vehicle in which at least the rear wheels (non-steered wheels) are drive wheels, and may be a 4WD vehicle as well as an FR vehicle. In the case of a 4WD car, there is no rolling wheel (non-driving wheel), so when the driving wheel of the vehicle 1 slips, the actual values of distance and speed are estimated based on the wheel speed sensor value of the driving wheel From this, it can not be switched to estimate based on the wheel speed sensor value of the rolling wheel. Therefore, switching may be performed so as to estimate based on at least one of peripheral image data of the vehicle 1 captured by the on-vehicle camera and a detection value from the acceleration sensor.

As mentioned above, although the embodiment of the present invention was illustrated, the above-mentioned embodiment is an example to the last, and limiting the scope of the present invention is not intended. The above embodiment can be implemented in other various forms, and various omissions, replacements, combinations, and changes can be made without departing from the scope of the invention. In addition, the specifications (structure, type, number, etc.) of each configuration, shape, etc. can be appropriately changed and implemented.

For example, although the above-mentioned embodiment explained a case where a coefficient of friction of a road surface was low, run control device 100 of an embodiment is applicable also when a slope and a level difference exist on a road surface.

Claims

A travel control device for controlling the travel of a vehicle in which at least the rear wheels are drive wheels,
An operation amount calculation unit that calculates an operation amount for controlling at least one of the drive mechanism and the braking mechanism of the vehicle so as to reduce the deviation between the target position and the actual position of the vehicle
A determination unit that calculates the actual position based on a detection value from a sensor that detects the rotation of the drive wheel, and determines whether the drive wheel has slipped;
The target position is set while changing with the passage of time, and when it is determined by the determination unit that the drive wheel has slipped, the determination unit determines that the slip of the drive wheel has been eliminated. A target position setting unit for stopping the update of the target position;
The travel control device, wherein the determination unit calculates the actual position based on data other than a detection value from a sensor that detects the rotation of the drive wheel after determining that the drive wheel has slipped.
In the vehicle, the front wheels are rolling wheels,
The travel control device according to claim 1, wherein the determination unit calculates the actual position based on a detection value from a sensor that detects rotation of the rolling wheel after determining that the driving wheel has slipped.
The determination unit calculates the actual position based on at least one of peripheral image data of the vehicle captured by the on-vehicle camera and a detection value from an acceleration sensor after determining that the drive wheel has slipped. The travel control device according to claim 1.
The operation amount calculation unit is configured to calculate the operation amount not to exceed the operation amount when the drive wheel slips after it is determined by the determination unit that the drive wheel has slipped. The travel control device according to any one of claims 3 to 10.