JP7377940B2 - Control device and vehicle - Google Patents

Description

The present disclosure relates to a following driving system for causing a leading vehicle to follow a following vehicle.

2. Description of the Related Art A vehicle control device that causes a host vehicle to follow a leading vehicle is known (for example, Patent Document 1). The vehicle control device disclosed in Patent Document 1 calculates a target braking force based on acceleration/deceleration information such as a target acceleration/deceleration value of a leading vehicle. Next, the vehicle control device controls the wheel cylinder pressure of each wheel so that the target braking force is obtained.

Unexamined Japanese Patent Publication No. 2017-1671

In the vehicle of Patent Document 1, the wheel cylinder pressure of each wheel is controlled by an electric motor. Since a predetermined delay occurs until the target braking force is obtained by driving the electric motor, there is a problem in that the responsiveness of the following vehicle decreases.

In view of the above background, an object of the present invention is to improve the following performance of a following vehicle in a following driving system.

In order to solve the above problems, an aspect of the present invention is a following driving system (1) that causes a following vehicle (2F) to follow a leading vehicle (2L), and is provided in the leading vehicle and controls the accelerator opening. a leading vehicle sensor (9L) that acquires the running state of the leading vehicle, a hydraulic brake device (6) that is provided on the trailing vehicle and applies braking torque to the trailing vehicle according to brake fluid pressure; A following vehicle control device (12F) installed in the vehicle and capable of controlling the hydraulic brake device; and transmitting the driving state of the leading vehicle including the accelerator opening obtained by the leading vehicle sensor to the following vehicle controlling device. and an inter-vehicle communication device (11), wherein the following vehicle control device instantaneously changes the brake fluid pressure of the hydraulic brake device when the accelerator opening degree of the leading vehicle is returned at a speed higher than a predetermined speed. The feature is that a preload process is performed to increase the pressure.

According to this aspect, when the accelerator opening degree of the lead vehicle is returned to a predetermined speed or higher, the hydraulic brake is momentarily increased. This makes it possible to shorten the time from when braking force is applied to the leading vehicle until braking force is applied to the following vehicle. Therefore, the following performance of the following vehicle can be improved.

In the above aspect, the following vehicle control device controls the following vehicle control device when the accelerator opening degree of the leading vehicle changes from a predetermined high opening degree or more to a predetermined low opening degree or less within a predetermined time. It is preferable to determine that the accelerator opening degree of the lead vehicle has been returned to a predetermined speed or higher, and then execute the preload process.

According to this aspect, it can be easily determined that the driver of the lead vehicle has returned the accelerator opening at a speed higher than a predetermined speed.

In the above aspect, the following vehicle is provided with a following vehicle sensor (9F) that acquires the running state of the following vehicle including deceleration, and a traveling drive electric motor (4), and the following vehicle control device calculates the target deceleration of the following vehicle based on the driving condition of the leading vehicle and the driving condition of the following vehicle, and when the target deceleration is larger than a predetermined threshold value, calculates the deceleration of the following vehicle. A cooperative control process is executed to control the regenerative torque of the travel drive electric motor and the braking torque of the hydraulic brake device in order to match the target deceleration, and when the target deceleration is less than the threshold value, the following In order to make the deceleration of the vehicle coincide with the target deceleration, it is preferable to execute an independent control process for controlling the regenerative torque of the travel drive electric motor.

According to this aspect, when the target deceleration is equal to or greater than the threshold value, braking torque by the hydraulic brake is applied in addition to the regenerative torque. This allows more reliable braking force to be applied to the following vehicle when deceleration equal to or greater than the threshold value is required.

In the above aspect, the following vehicle control device preferably executes the preload process before executing the cooperative control process or the independent control process.

According to this aspect, by performing the preload process before the cooperative control process or the independent control process, braking force can be applied more quickly to the following vehicle. Thereby, it is possible to improve the following performance of the following vehicle.

In the above aspect, the following vehicle control device controls the target deceleration so that the target deceleration increases as the inter-vehicle distance between the leading vehicle and the following vehicle becomes smaller than a predetermined target inter-vehicle distance. It is recommended to calculate.

According to this aspect, when the inter-vehicle distance becomes smaller than the target inter-vehicle distance, the following vehicle is further decelerated, and when it becomes larger than the target inter-vehicle distance, the following vehicle is less likely to be decelerated. Thereby, the following vehicle can be controlled so that the following vehicle distance becomes the target vehicle distance.

In the above aspect, the following vehicle control device sets the target deceleration so that the target deceleration increases as the difference between the speed of the leading vehicle and the speed of the following vehicle before a predetermined inter-vehicle time becomes smaller. It is best to calculate it.

According to this aspect, the following vehicle is controlled so as to travel at a speed that is earlier than the inter-vehicle time of the leading vehicle. This allows the following vehicle to appropriately follow the leading vehicle.

In the above aspect, the following vehicle control device acquires the generated torque generated in the wheels of the leading vehicle based on the signal from the leading vehicle sensor, and determines whether the generated torque is generated in order to decelerate the leading vehicle. It is preferable to calculate the target deceleration so that the target deceleration increases when the vehicle is running.

According to this aspect, since the following vehicle is controlled based on the torque generated by the leading vehicle, it is possible to compensate for the time delay until the following vehicle decelerates, and it is possible to improve the following performance of the following vehicle. can.

In the above aspect, the lead vehicle is provided with a lead vehicle control device that controls the vehicle based on the accelerator opening, and the lead vehicle control device controls when the accelerator opening is equal to or greater than a predetermined reference value. It is preferable that the leading vehicle is accelerated when the accelerator opening is less than the reference value, and the leading vehicle is decelerated when the accelerator opening is less than the reference value.

According to this aspect, the acceleration and deceleration of the lead vehicle can be operated by one pedal, so that the acceleration and deceleration operations are simplified.

In the above aspect, the range of torque that the leading vehicle control device can output to the wheels of the leading vehicle due to accelerator operation of the leading vehicle is the range of torque that the trailing vehicle control device can output to the wheels of the trailing vehicle. It is good if it is within the range of .

According to this aspect, the torque to be output to the wheels of the following vehicle can be more reliably varied in accordance with the torque fluctuation of the leading vehicle, so that the following vehicle can be made to follow the leading vehicle more reliably.

According to the above configuration, the tracking performance of the following vehicle can be improved in the tracking system.

Configuration diagram of a vehicle equipped with a tracking system according to this embodiment Flowchart of deceleration processing A graph showing temporal changes in the acceleration of the leading vehicle and the following vehicle and temporal changes in the brake fluid pressure of the leading vehicle and the following vehicle when the target deceleration is equal to or higher than the deceleration threshold A graph showing temporal changes in the acceleration of the leading vehicle and following vehicles and temporal changes in the brake fluid pressure of the leading vehicle and following vehicles when the target deceleration is less than the deceleration threshold.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a tracking system according to the present invention will be described with reference to the drawings.

The following driving system 1 is a system for causing one vehicle 2 (hereinafter referred to as a leading vehicle 2L) to follow another vehicle 2 (hereinafter referred to as a following vehicle 2F). In the following, a case will be described in which the following driving system 1 is applied to the case where the leading vehicle 2L is caused to follow one following vehicle 2F.

The leading vehicle 2L and the following vehicle 2F are four-wheeled electric vehicles that run on electric power, and include a motor 4 (electric motor), a battery 5, a hydraulic brake device 6, a steering device 7, an accelerator pedal 8, a vehicle sensor 9, and external world recognition. The vehicle includes a device 10, an inter-vehicle communication device 11, and a control device 12.

Each of the motors 4 is an electric motor for running drive that uses electric power stored in a battery 5 as an energy source and applies a driving torque to the driving wheels of the corresponding vehicle 2. The wheels are rotated by the drive torque applied by the motor 4, and the vehicle 2 runs. In this embodiment, the rear wheels of the leading vehicle 2L and the following vehicle 2F serve as driving wheels of the leading vehicle 2L and the following vehicle 2F, respectively.

Further, each motor 4 also functions as a regenerative brake. That is, during braking, the motor 4 converts the rotational force of the wheels into electric power and returns the electric power to the battery 5, thereby applying regenerative torque to the wheels as a braking force.

In this embodiment, the motor 4 is connected to a motor driver 14. This motor driver 14 is connected to the battery 5 and controls the driving of the motor 4. More specifically, when the vehicle 2 is driving, electric power from the battery 5 is supplied to the motor 4 to control the driving torque generated by the motor 4. When the vehicle 2 is braking, the electric power generated by the motor 4 is returned to the battery 5 to charge the battery 5, and the regenerative torque generated by the motor 4 is controlled. Hereinafter, the difference between the drive torque and the regenerative torque will be referred to as the generated torque generated by the motor 4.

The hydraulic brake device 6 includes brake calipers 15 provided on each wheel. The brake calipers 15 each include a wheel cylinder (not shown), an electric actuator 16 that generates hydraulic pressure in the wheel cylinder, a piston (not shown) provided in the wheel cylinder, and are displaced according to the position of the piston. A brake pad 17 is provided. Hydraulic brake device 6 includes a brake ECU 18 that controls electric actuator 16 . In this embodiment, the electric actuator 16 is constituted by a hydraulic pump that generates oil pressure in the wheel cylinder, and it takes a predetermined operating time from the start of pressurization until the oil pressure in the wheel cylinder reaches a predetermined pressure. The brake ECU 18 is connected to the control device 12, controls the drive of the electric actuator 16 based on a signal from the control device 12, and generates oil pressure in the wheel cylinder. The hydraulic pressure generated in the wheel cylinder presses the brake pad 17 against the disc rotor 19, which rotates together with the wheel, and applies frictional braking torque to each wheel. The control device 12 controls the hydraulic pressure in the wheel cylinders (hereinafter referred to as brake fluid pressure) by controlling the drive of the electric actuator 16, thereby controlling the magnitude of the frictional braking torque applied to each wheel. In this embodiment, the controller 12 applies approximately the same friction braking torque to each wheel.

The accelerator pedal 8 is provided in front of the driver's seat at a position corresponding to the driver's feet. The driver can perform driving operations by depressing the accelerator pedal 8.

The steering device 7 is a device for steering the vehicle 2, and includes a steering ECU 21 and a steering drive device 22. The steering drive device 22 may be, for example, an electric motor that applies force to a rack and pinion mechanism to change the steering angle of the steered wheels (front wheels) based on a signal from the steering ECU 21 .

The vehicle sensor 9 is a sensor that detects the running state of the vehicle 2 in which it is mounted (hereinafter referred to as the own vehicle 2), and includes an accelerator sensor 25, a hydraulic pressure sensor 26, an inertial measurement unit 27 (IMU), and a steering angle sensor 25, a hydraulic pressure sensor 26, an inertial measurement unit 27 (IMU), and a steering angle sensor 28. The accelerator sensor 25 is provided on the accelerator pedal 8 and is a sensor that detects the amount of operation (accelerator opening degree) of the accelerator pedal 8 by the driver. The hydraulic pressure sensor 26 is a sensor provided in a wheel cylinder that detects a brake hydraulic pressure value. The inertial measurement device 27 includes an acceleration sensor and an angular velocity sensor, and detects the acceleration and angular velocity of the own vehicle 2. In this embodiment, the inertial measurement device 27 includes a speed sensor and can detect the speed of the own vehicle 2. The steering angle sensor 28 may be a known sensor that is provided on the steering shaft and detects the steering angle of the steered wheels.

The external world recognition device 10 is a sensor for acquiring the positions (i.e., relative positions) of surrounding vehicles with respect to the own vehicle 2. The external world recognition device 10 may include, for example, a stereo camera that images the front of the vehicle 2, and at least one of a millimeter wave radar, a lidar, and a sonar that detect an object located in front of the vehicle 2.

The inter-vehicle communication device 11 is a device that mediates communication between the control device 12 of the own vehicle 2 and the control device 12 of another vehicle 2 other than the own vehicle 2. Communication between the vehicle-to-vehicle communication devices 11 may be performed using electromagnetic waves including light, or may be performed using sound waves including ultrasonic waves.

The control device 12 is an electronic control unit (ECU) configured by a computer including a CPU, ROM, RAM, and the like. The control device 12 is connected to the vehicle sensor 9, the external world recognition device 10, the inter-vehicle communication device 11, the steering ECU 21, the brake ECU 18, and the motor driver 14 so as to be able to transmit signals through communication means such as a CAN 30 (Controller Area Network). The control device 12 may be configured as one piece of hardware, or may be realized by a unit consisting of a plurality of hardware, or a combination of software and hardware.

The control device 12 (leading vehicle control device 12L) of the leading vehicle 2L acquires the running state of the own vehicle 2 from the vehicle sensor 9 (leading vehicle sensor 9L) mounted on the leading vehicle 2L, and communicates the driving state of the own vehicle 2 via the inter-vehicle communication device 11. It is transmitted to the control device 12 of the car 2F. The running state includes speed, acceleration, accelerator opening, and brake fluid pressure value. Further, the control device 12 of the lead vehicle 2L acquires the accelerator opening degree from the accelerator sensor 25, and controls the drive of the host vehicle 2. More specifically, the control device 12 of the lead vehicle 2L applies torque to the wheels to accelerate the lead vehicle 2L when the accelerator opening is equal to or greater than a predetermined reference value. The control device 12 of the leading vehicle 2L applies torque to the wheels to decelerate the leading vehicle 2L when the accelerator opening is less than a reference value. The torque applied to the wheels of the leading vehicle 2L to decelerate the leading vehicle 2L may be based on regenerative torque, may be based on frictional braking torque, or may include both. In this way, the driver can accelerate or decelerate the vehicle 2 by operating the accelerator pedal 8, and therefore can easily perform driving operations.

However, when the following vehicle 2F is following the leading vehicle 2L, the range of torque that the control device 12 of the leading vehicle 2L can output to the wheels by the driver's accelerator operation is limited to that of the following vehicle 2F. The torque is limited within the range of torque that the control device 12 can output to the wheels of the following vehicle 2F. Thereby, the torque to be output to the wheels of the following vehicle 2F can be more reliably varied in accordance with the torque fluctuation of the leading vehicle 2L. Therefore, it becomes possible to apply sufficient torque to the wheels of the following vehicle 2F in accordance with the acceleration/deceleration of the leading vehicle 2L, and it is possible to make the following vehicle 2F follow the leading vehicle 2L more reliably.

The control device 12 (following vehicle control device 12F) of the following vehicle 2F acquires the driving state of the leading vehicle 2L and the position of the leading vehicle 2L with respect to the own vehicle 2 via the inter-vehicle communication device 11. Thereafter, the control device 12 of the following vehicle 2F controls the acquired driving state of the leading vehicle 2L, the relative position of the leading vehicle 2L, and the own vehicle acquired by the vehicle sensor 9 (following vehicle sensor 9F) mounted on the following vehicle 2F. 2 (following vehicle 2F), the target steering angle is calculated. The control device 12 of the following vehicle 2F controls the following vehicle 2F to pass through the traveling trajectory of the leading vehicle 2L by controlling the steering ECU 21 so that the steering angle becomes the target steering angle.

Further, the control device 12 of the following vehicle 2F calculates the inter-vehicle distance between the leading vehicle 2L and the following vehicle 2F based on the relative position of the leading vehicle 2L acquired by the external world recognition device 10. That is, the external world recognition device 10 functions as an external world information acquisition device that acquires external world information for acquiring the inter-vehicle distance between the leading vehicle 2L and the following vehicle 2F.

The control device 12 of the following vehicle 2F ensures that while the following vehicle 2F is following the leading vehicle 2L, the inter-vehicle distance between the leading vehicle 2L and the following vehicle 2F is constant, and the control device 12 of the following vehicle 2F is configured to The host vehicle 2 is controlled so that the difference between the speed of the vehicle 2L and the speed of the host vehicle 2 before a predetermined inter-vehicle time (hereinafter referred to as vehicle speed deviation) is zero. More specifically, the control device 12 of the following vehicle 2F calculates the target acceleration so that the inter-vehicle distance is constant and the vehicle speed deviation is zero. Next, the control device 12 of the following vehicle 2F controls the torque generated by the motor 4 of the own vehicle 2 and the brake fluid pressure so that the acceleration of the own vehicle 2 becomes equal to the target acceleration. The target acceleration calculated by the control device 12 of the following vehicle 2F is expressed by the following formula.

The control device 12 of the following vehicle 2F calculates the target inter-vehicle distance D _tg (t) [m] and inter-vehicle time T _gap [s] in Equation (1) using the following Equation (2) and Equation (3). ing.

In equation (1), ACC _TAR (t) [G] is the target acceleration, TQ _lC (t) [Nm] is the generated torque generated by the motor 4 of the leading vehicle 2L at time t [s], and PQ _lC (t) [MPa] is the brake fluid pressure of the leading vehicle 2L. D _tg (t)[m] is the target inter-vehicle distance at time t[s], and D(t)[m] is the inter-vehicle distance at time t[s]. Vfc (t) [m/s] is the speed of the following vehicle 2F at time t [s], and V _lc (t) [m/s] is the speed of the leading vehicle 2L at time t [s]. T _gap [s] is the inter-vehicle time.

In equation (2), D _min [m] is the target minimum inter-vehicle distance. In equation (3), V [m/s] is a predetermined vehicle speed suitable for follow-up travel, and T ₀ [s] is a predetermined additional time. In this embodiment, D _min [m] is set to 1.0 m and T ₀ is set to 0.2 seconds. The additional time may be determined based on the time required for a human to respond (hereinafter referred to as response time).

Further, _CT2A indicates a positive coefficient for converting the generated torque into a contribution to the acceleration of the following vehicle 2F. As shown in equation (1), when the control device 12 of the following vehicle 2F is generating torque to decelerate the leading vehicle 2L, that is, when the generated torque is negative, the target acceleration is decreased. Therefore, when the generated torque is negative, the target deceleration increases. Thereby, while the leading vehicle 2L is decelerating, the following vehicle 2F is decelerated.

_CP2A indicates a positive coefficient for converting the brake fluid pressure into a contribution to the acceleration of the following vehicle 2F. The control device 12 of the following vehicle 2F generates brake fluid pressure to decelerate the leading vehicle 2L, and when frictional braking torque is applied to the wheels of the leading vehicle 2L, the target acceleration decreases. Thereby, while the leading vehicle 2L is decelerating, the following vehicle 2F is decelerated.

That is, the sum of the first and second terms after the equal sign in equation (1) indicates the predicted value of the acceleration generated in the leading vehicle 2L due to the generated torque and the braking force by the brake, and is a feedforward value for the inter-vehicle distance and vehicle speed deviation. corresponds to the section. Thereby, it is possible to compensate for the time delay until the following vehicle 2F is decelerated by applying braking force. Therefore, the following performance of the following vehicle 2F can be improved.

In equation (1), C _D2A is a positive coefficient for converting the difference in inter-vehicle distance from the target inter-vehicle distance (D _tg (t) - D(t), hereinafter referred to as inter-vehicle deviation) into a contribution to the acceleration of the following vehicle 2F. It is a coefficient. The third term after the equal sign in equation (1) (-(C _D2A (D _tg (t) - D(t))) (hereinafter referred to as the distance deviation term) indicates that the distance deviation is positive, that is, the following vehicle 2F is leading. It becomes negative when the distance is closer to the vehicle 2L than the target inter-vehicle distance. That is, when the inter-vehicle distance is larger than the target inter-vehicle distance and the inter-vehicle deviation is positive, the target acceleration decreases, the following vehicle 2F moves away from the leading vehicle 2L, and the inter-vehicle deviation becomes smaller. Similarly, when the inter-vehicle distance is smaller than the target inter-vehicle distance and the inter-vehicle deviation is negative, the target acceleration increases, the following vehicle 2F approaches the leading vehicle 2L, and the inter-vehicle deviation becomes smaller. That is, the inter-vehicle deviation term corresponds to a feedback term that brings the inter-vehicle deviation closer to zero, and is controlled so that the inter-vehicle distance becomes the target inter-vehicle distance.

Furthermore, C _V2A is the difference in speed of the leading vehicle 2L at the time T _gap before time t with respect to the speed of the following vehicle 2F at time t (V _fc (t) - V _lc (t - T _gap ). Hereinafter, This is a positive coefficient for converting the vehicle speed deviation) into a contribution to the acceleration of the following vehicle 2F. The fourth term after the equal sign in equation (1) (-C _V2A (V _fc (t) - V _lc (t - T _gap ))) indicates that the vehicle speed deviation is positive, that is, the speed of the following vehicle 2F is equal to that of the leading vehicle 2L. It becomes negative when the speed is greater than the speed before the inter-vehicle time. That is, when the vehicle speed deviation is positive, the target acceleration decreases, the speed of the following vehicle 2F approaches the speed of the leading vehicle 2L before the inter-vehicle time, and the vehicle speed deviation becomes small. Similarly, when the vehicle speed deviation is negative, the target acceleration increases, the speed of the following vehicle 2F increases, and the vehicle speed deviation becomes smaller. That is, the vehicle speed deviation term corresponds to a feedback term that brings the vehicle speed deviation closer to zero, and the following vehicle 2F is feedback-controlled so as to travel at a speed before the inter-vehicle time of the leading vehicle 2L. This allows the following vehicle 2F to appropriately follow the leading vehicle 2L.

The control device 12 of the following vehicle 2F performs the deceleration process shown in FIG. 2 when the target acceleration is negative, that is, when the target deceleration is positive. The details of the deceleration process will be described below with reference to FIG. 2.

As shown in FIG. 2, in the first step ST1 of the deceleration process, it is determined based on the accelerator opening degree whether the driver of the lead vehicle 2L has depressed the accelerator pedal 8 back. More specifically, the control device 12 of the following vehicle 2F acquires the driving state of the leading vehicle 2L including the accelerator opening obtained by the leading vehicle 2L sensor (accelerator opening sensor) via the inter-vehicle communication device 11. . Thereafter, the control device 12 of the following vehicle 2F determines whether or not the accelerator opening degree of the leading vehicle 2L has been returned at a speed higher than a predetermined speed, thereby determining whether the driver of the leading vehicle 2L has pressed the accelerator pedal 8 back. Determine whether or not. In this embodiment, the control device 12 of the following vehicle 2F moves the accelerator opening of the leading vehicle 2L from a position above a high opening threshold, which is a predetermined threshold, to a position below a low opening threshold, which is a predetermined threshold. When the accelerator opening degree of the lead vehicle 2L changes within the time (hereinafter referred to as determination time), it is determined that the accelerator opening degree of the lead vehicle 2L has been returned at a speed equal to or higher than a predetermined speed. The high opening threshold is preferably set to about 30%, and the low opening threshold is preferably set to 0%. The determination time is preferably set to be equal to the response time (0.2 seconds). If the accelerator opening degree of the leading vehicle 2L is returned to a predetermined speed or higher, the control device 12 of the following vehicle 2F executes step ST2; otherwise, the control device 12 of the following vehicle 2F executes step ST3. Execute the process.

In step ST2, the control device 12 of the following vehicle 2F controls the brake ECU 18 to perform a preload process to instantaneously increase the brake fluid pressure of the hydraulic brake device 6. More specifically, the control device 12 of the following vehicle 2F controls the brake ECU 18 so that the brake fluid pressure of the following vehicle 2F reaches a predetermined brake prepressure value P _τ when a predetermined prepressure time τ has elapsed. Increase brake fluid pressure. In this embodiment, the preload time τ is set equal to the response time (0.2 seconds). The brake prepressure value P _τ is set to a brake fluid pressure that applies a deceleration of approximately 0.05 G to the following vehicle 2F. When the preload time τ has elapsed and the brake fluid pressure of the following vehicle 2F reaches the brake preload value _Pτ , the control device 12 of the following vehicle 2F executes the process of step ST3.

In step ST3, the control device 12 of the following vehicle 2F calculates the target deceleration by inverting the sign of the target acceleration calculated using equation (1) (that is, multiplying by (-1)). Next, the control device 12 of the following vehicle 2F determines whether the target deceleration is larger than a predetermined deceleration threshold. The deceleration threshold DEC _lim is set to be equal to the deceleration applied to the following vehicle 2F (hereinafter referred to as maximum regenerative deceleration) when the motor 4 outputs the maximum regenerative torque that it can output. The control device 12 of the following vehicle 2F executes step ST4 when the target deceleration is greater than the deceleration threshold, and executes step ST5 when the target deceleration is less than or equal to the deceleration threshold.

In step ST4, the control device 12 of the following vehicle 2F performs a cooperative control process to control the regenerative torque generated by the motor 4 and the friction braking torque generated by the hydraulic brake in order to make the deceleration of the following vehicle 2F match the target deceleration. Execute. At this time, the control device 12 of the following vehicle 2F is preferably controlled to increase the frictional braking torque and reduce the contribution of the regenerative torque within the range in which the regenerative torque and the frictional braking torque can each be changed. As a result, the contribution of frictional braking torque increases, so even if the output range of regenerative torque decreases due to reasons such as an excessive charge amount of the battery 5, braking force is applied more reliably to the following vehicle 2F. This allows the acceleration of the following vehicle 2F to approach the target acceleration more reliably. The control device 12 of the following vehicle 2F updates the target acceleration at predetermined time intervals, executes the cooperative control process as long as the target acceleration is negative, and completes step ST4 when the target acceleration becomes positive. Finish the deceleration process.

In step ST5, the control device 12 of the following vehicle 2F sets the friction braking torque to zero and performs an independent control process to control the regenerative torque generated by the motor 4 in order to make the deceleration of the following vehicle 2F match the target deceleration. Execute. The control device 12 of the following vehicle 2F updates the target acceleration at predetermined time intervals, and executes the independent control process as long as the target acceleration is negative. When the target acceleration becomes positive, the control device 12 of the following vehicle 2F completes step ST5 and ends the deceleration process.

Next, the operation and effects of the tracking system 1 according to the present invention will be explained with reference to FIGS. 3 and 4. FIGS. 3 and 4 show the temporal change in the acceleration a _l [G] of the leading vehicle 2L and the brake of the leading vehicle 2L when the driver of the leading vehicle 2L reduces the accelerator opening at a speed higher than a predetermined speed. The time changes in the hydraulic pressure P _l [MPa] are shown by solid lines, and the time changes in the acceleration a _fw [G] of the following vehicle 2F and the time changes in the brake fluid pressure P _fw [MPa] of the following vehicle 2F are shown by broken lines. ing. In FIGS. 3 and 4, the time t at which the driver of the lead vehicle 2L reduces the accelerator opening at a speed greater than a predetermined speed is set to 0. 3 corresponds to the case where the target deceleration calculated in step ST3 is larger than the deceleration threshold, and FIG. 4 corresponds to the case where the target deceleration calculated in step ST3 is less than or equal to the deceleration threshold. There is. FIG. 4 shows an example in which the leading vehicle 2L decelerates only by regenerative torque. FIG. 3 shows the time change of the brake fluid pressure P _fo [MPa] of the following vehicle 2F and the time change of the acceleration a _fo [G] of the following vehicle 2F when the preload process in step ST4 is not performed. It is shown for reference by the dash-dotted line.

When the accelerator opening degree decreases at a speed equal to or higher than a predetermined value at time t=0, the control device 12 of the following vehicle 2F determines in step ST3 that the driver of the leading vehicle 2L has depressed the accelerator pedal 8, and in step ST4. Execute the preload process. At this time, as shown in FIG. 3, when the driver of the leading vehicle 2L depresses the accelerator pedal 8 back (t=0), a preload process is executed and the electric actuator 16 is driven, and the brake fluid pressure of the following vehicle 2F is There is a predetermined delay time Δt before the start of the rise.

The prepressure process increases the brake fluid pressure of the following vehicle 2F, and after the prepressure time τ, the brake fluid pressure reaches the brake prepressure value P _τ . As a result, frictional braking torque corresponding to the brake fluid pressure is applied to the wheels of the following vehicle 2F, and the acceleration of the following vehicle 2F decreases as the brake fluid pressure increases.

It is preferable that the sum of the delay time Δt and the preload time τ is set to be greater than or equal to the inter-vehicle time T _gap . As a result, the target acceleration becomes negative between the start of deceleration of the leading vehicle 2L and the completion of the preload processing of the following vehicle 2F, so the deceleration of the following vehicle 2F does not stop after the preload processing, and the deceleration of the following vehicle 2F is smoothly achieved. will continue.

If the target deceleration is equal to or greater than the deceleration threshold, the control device 12 of the following vehicle 2F executes the cooperative control process (ST4) after the preload process is completed. Thereby, the regenerative torque and the friction braking torque are controlled so that the deceleration of the following vehicle 2F matches the target deceleration. At this time, the brake fluid pressure of the following vehicle 2F increases more slowly over time than during the preload process. In FIG. 3, after the deceleration of the following vehicle 2F matches the target deceleration, the deceleration of the following vehicle 2F changes approximately in the same way as the deceleration of the leading vehicle 2L before the inter-vehicle time T _gap . In this way, in the cooperative control process, regenerative torque and frictional braking torque from the hydraulic brake are applied to the wheels of the following vehicle 2F, so even if the frictional braking torque from the hydraulic brake alone is insufficient, the following Braking force can be applied more reliably to the vehicle 2F.

As shown by the two-dot chain line in FIG. 3, when the control device 12 of the following vehicle 2F executes the cooperative control process without preloading, the brake fluid pressure becomes more gradual than when preloading is performed. To increase. That is, by performing the preload process, it is possible to shorten the time until the deceleration of the following vehicle 2F becomes equal to the deceleration of the leading vehicle 2L before the inter-vehicle time T _gap . This makes it difficult for the inter-vehicle distance to shorten due to deceleration of the leading vehicle 2L. Therefore, the following performance of the following vehicle 2F can be improved.

Since the preload process makes it difficult for the inter-vehicle distance to become short, the inter-vehicle distance between the leading vehicle 2L and the following vehicle 2F can be set smaller than when the preload process is not provided. This allows the plurality of vehicles 2 to appropriately follow each other even in environments where it is desirable to travel with as close an inter-vehicle distance as possible (for example, in a city area).

As shown in FIG. 4, when the target deceleration is less than the deceleration threshold, the control device 12 of the following vehicle 2F executes the independent control process (ST5) after the preload process is completed. As a result, the regenerative torque is controlled so that the deceleration of the following vehicle 2F matches the target deceleration, and the friction torque becomes zero. Therefore, regenerative energy can be efficiently recovered.

As shown in FIG. 4, the preload process may cause the following vehicle 2F to be decelerated more than the leading vehicle 2L, resulting in an increase in the inter-vehicle distance. In this case, after the preload process, the regenerative torque may be controlled so that the deceleration of the following vehicle 2F is smaller than the deceleration of the leading vehicle 2L before the inter-vehicle time T _gap . Thereby, even if the inter-vehicle distance increases due to the preload process, the regenerative torque is controlled so that the inter-vehicle distance decreases after the preload process, so the inter-vehicle distance can be maintained more appropriately.

Although the description of the specific embodiments has been completed above, the present invention is not limited to the above-mentioned embodiments and can be widely modified and implemented. In the embodiment described above, the leading vehicle 2L and the following vehicle 2F communicate with each other via the inter-vehicle communication device 11, but the present invention is not limited to this mode. For example, the control devices 12 of the leading vehicle 2L and the following vehicle 2F may each be configured to be able to communicate with a base station wirelessly, and the control devices 12 may be configured to communicate with each other via the base station.

In the embodiment described above, the inertial measurement device 27 includes a speed sensor in addition to an acceleration sensor and an angular velocity sensor, but is not limited to this aspect. The inertial measurement device 27 may not include a speed sensor, and the vehicle sensor 9 may be configured to include the inertial measurement device 27 and a speed sensor. In addition, the control device 12 and the inertial measurement device 27 cooperate to function as a so-called inertial navigation device that obtains velocity, position, and attitude angle by integrating the acceleration and angular velocity obtained by the acceleration sensor and the angular velocity sensor. It may be configured to do so.

1: Following driving system 2: Vehicle 2F: Following vehicle 2L: Leading vehicle 4: Motor 6: Hydraulic brake device 9: Vehicle sensor 9F: Following vehicle sensor 9L: Leading vehicle sensor 11: Inter-vehicle communication device 12: Control device 12F: Following Vehicle control device 12L: Leading vehicle control device

Claims (8)

A control device that acquires the driving state of the leading vehicle including the accelerator opening from the leading vehicle and controls a following vehicle to follow the leading vehicle,
The brake fluid pressure of the hydraulic brake device is configured to be able to control a hydraulic brake device that applies braking torque according to brake fluid pressure, and when the accelerator opening of the lead vehicle is returned at a speed higher than a predetermined speed, the brake fluid pressure of the hydraulic brake device is controlled. A control device characterized by executing preload processing to instantaneously increase the pressure. When the accelerator opening degree of the leading vehicle changes from a position above a predetermined high opening degree to a position below a predetermined low opening degree within a predetermined time, the accelerator opening degree of the leading vehicle reaches a speed above a predetermined opening degree. 2. The control device according to claim 1, wherein the control device determines that the pressure has been returned and executes the preload process. connected to a following vehicle sensor that acquires the running state of the following vehicle including deceleration, and an electric motor for driving drive;
Calculating a target deceleration of the following vehicle based on the driving condition of the leading vehicle and the driving condition of the following vehicle;
When the target deceleration is larger than a predetermined threshold, coordination controls the regenerative torque of the travel drive electric motor and the braking torque of the hydraulic brake device so that the deceleration of the following vehicle matches the target deceleration. Execute control processing,
When the target deceleration is less than the threshold, an independent control process is executed to control the regenerative torque of the travel drive electric motor so that the deceleration of the following vehicle matches the target deceleration. The control device according to claim 1 or claim 2. 4. The control device according to claim 3, wherein the preload process is executed before executing the cooperative control process or the independent control process. 3. The target deceleration is calculated such that the target deceleration increases when the inter-vehicle distance between the leading vehicle and the following vehicle is smaller than a predetermined target inter-vehicle distance. Or the control device according to claim 4. According to any one of claims 3 to 5, the target deceleration is calculated so as to reduce a difference between the speed of the leading vehicle before a predetermined inter-vehicle time and the speed of the following vehicle. Control device as described in Section . The driving state of the leading vehicle including the generated torque generated from the leading vehicle to the wheels of the leading vehicle is acquired, and when the generated torque is being generated to decelerate the leading vehicle, the target deceleration is increased. The control device according to any one of claims 3 to 6, characterized in that the target deceleration is calculated in a step of calculating the target deceleration. A vehicle equipped with a control device according to any one of claims 1 to 7.

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