Mobile body control device, mobile body control method, and program

Abstract

To provide a mobile body control device capable of maintaining the followability to a preceding mobile body while suppressing a fade phenomenon of a braking device.SOLUTION: A mobile body control device 15 includes an acceleration acquisition unit 42, a gradient acquisition unit 43, a preceding mobile body detection unit 44, and a follow control unit 45. The follow control unit calculates target acceleration on the basis of the distance between the mobile body and the preceding mobile body and a target distance, and starts suppression control to calculate corrected target acceleration obtained by reducing the absolute value of the target acceleration when such conditions that the magnitude of the down grade of a travel path is equal to or greater than a predetermined gradient determination value, and the difference between the target acceleration and the actual acceleration is equal to or less than a predetermined difference determination value are satisfied. While the follow control unit is executing the suppression control, a propulsion device and a braking device are controlled on the basis of the corrected target acceleration instead of the target acceleration.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a movement control device, a movement control method, and a program.

Background Art

[0002] In recent years, efforts have been actively made to provide a sustainable transportation system that takes into account people in vulnerable positions among traffic participants. In order to further improve traffic safety and convenience towards this realization, research and development on driving support technologies and autonomous driving technologies have been carried out.

[0003] Patent Document 1 discloses a vehicle control device that executes following driving with respect to a preceding vehicle. This vehicle control device switches a map used for control between a normal map and a fade suppression map based on the temperature of the brake pads. When the fade suppression map is selected, the responsiveness of acceleration / deceleration control becomes gentler compared to when the normal map is selected. Thereby, the use of the brake is suppressed, and the brake being in a fade state is suppressed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, if the control based on the fade suppression map continues, the followability with respect to the preceding vehicle deteriorates, and there is a risk that it may become impossible to follow the preceding vehicle.

[0006] In view of the above background, an object of the present invention is to provide a movement control device, a movement control method, and a program that can suppress the fade phenomenon of a braking device while maintaining the followability with respect to a preceding moving body. Thereby, an object of the present invention is to contribute to the development of a sustainable transportation system.

Means for Solving the Problems

[0007] In order to solve the above problems, an aspect of the present invention is a movement control device (15) that controls the traveling of a moving body (1), the movement control device including: an acceleration acquisition unit (42) that acquires the actual acceleration of the moving body; a gradient acquisition unit (43) that acquires the gradient of the road on which the moving body travels; a preceding moving body detection unit (44) that detects a preceding moving body that moves ahead of the moving body; and a follow-up control unit (45) that executes follow-up control for calculating a target acceleration for controlling a propulsion device and a braking device so that the moving body follows the preceding moving body. The follow-up control unit calculates the target acceleration based on the distance between the moving body and the preceding moving body and a target distance, and starts suppression control for calculating a corrected target acceleration with the absolute value of the target acceleration decreased when the condition that the magnitude of the downhill gradient of the road is equal to or greater than a predetermined gradient determination value and the difference between the target acceleration and the actual acceleration is equal to or less than a predetermined difference determination value is satisfied. While the follow-up control unit is executing the suppression control, the propulsion device and the braking device are controlled based on the corrected target acceleration instead of the target acceleration.

[0008] According to this aspect, it is possible to provide a movement control device that can suppress the fade phenomenon of the braking device while maintaining the followability with respect to the preceding moving body. By executing the suppression control, the increase in acceleration becomes gentle, and the decrease in the distance between the moving body and the preceding moving body is suppressed. Thereby, the use of the braking device is suppressed, and the temperature rise and fade phenomenon of the braking device are suppressed. When the suppression control is executed, since the difference between the target acceleration and the actual acceleration is equal to or less than the difference determination value, even if the absolute value of the target acceleration is suppressed, the change in the distance between the moving body and the preceding moving body is suppressed.

[0009] In the above aspect, the following following control unit may start the suppression control when the following conditions are satisfied: the magnitude of the downward slope of the travel path is equal to or greater than a predetermined slope determination value, the difference between the target acceleration and the actual acceleration is equal to or less than a predetermined difference determination value, and the target acceleration is a value on the acceleration increasing side.

[0010] According to this aspect, it is possible to provide a movement control device capable of maintaining the followability with respect to the preceding vehicle while suppressing the fade phenomenon of the braking device. When the travel path is a downward slope, an acceleration in the acceleration increasing side is generated in the moving body by gravity. Therefore, even if the target acceleration on the acceleration increasing side is suppressed, the followability with respect to the preceding moving body is maintained.

[0011] In the above aspect, the following following control unit may stop the following control when the temperature of the braking device is equal to or higher than a predetermined temperature determination value.

[0012] According to this aspect, since the use of the braking device by the following control is stopped, the fade phenomenon is suppressed.

[0013] In the above aspect, the following following control unit may calculate the target acceleration so that the distance between the moving body and the preceding moving body approaches the target distance.

[0014] According to this aspect, the following following control unit can bring the distance between the moving body and the preceding moving body closer to the target distance.

[0015] In the above aspect, the following following control unit stops the suppression control when the difference between the target acceleration and the actual acceleration becomes greater than the difference determination value.

[0016] According to this aspect, the following following control unit can maintain the followability with respect to the preceding moving body. When the difference between the target acceleration and the actual acceleration is greater than the difference determination value, the distance between the preceding moving body and the moving body is likely to change. In such a case, the following following control unit stops the suppression control to improve the responsiveness of acceleration.

[0017] In the above aspect, when an input operation to a driving operation device that receives a driving operation of an occupant of the moving body is detected, the following control may be stopped.

[0018] According to this aspect, the occupant can stop the following control by his / her own operation.

[0019] In the above aspect, when the preceding moving body is no longer a following target, the following control may be stopped.

[0020] According to this aspect, the following control unit can stop unnecessary following control for a surrounding moving body that is not a following target.

[0021] In the above aspect, after the following control is stopped, the following control unit may execute a return process for suppressing a change amount of an absolute value of the target acceleration.

[0022] According to this aspect, when the following control is stopped, a rapid change in acceleration is suppressed.

[0023] In the above aspect, in the return process, the following control unit may suppress the change amount of the absolute value of the target acceleration based on a difference between the target acceleration and the actual acceleration.

[0024] According to this aspect, when the following control is stopped, a rapid change in acceleration is suppressed.

[0025] In the above aspect, when the following control unit is executing the following control, it may include a notification unit that notifies an occupant of the moving body that the following control is being executed.

[0026] According to this aspect, the occupant can recognize that the following control is being executed, and it becomes difficult to feel a sense of discomfort.

[0027] Another aspect of the present invention is a moving body control method executed by a computer to control the travel of a moving body, which includes acquiring the actual acceleration of the moving body, acquiring the gradient of the travel path on which the moving body travels, detecting a preceding moving body that moves ahead of the moving body, and performing a tracking control to calculate a target acceleration for controlling a propulsion device and a braking device so that the moving body follows the preceding moving body, calculating the target acceleration based on the distance between the moving body and the preceding moving body and a target distance, and starting a suppression control to calculate a corrected target acceleration with the absolute value of the target acceleration decreased when the condition that the magnitude of the downhill gradient of the travel path is equal to or greater than a predetermined gradient determination value and the difference between the target acceleration and the actual acceleration is equal to or less than a predetermined difference determination value is satisfied, and during the execution of the suppression control, the propulsion device and the braking device may be controlled based on the corrected target acceleration instead of the target acceleration.

[0028] According to this aspect, it is possible to provide a moving body control method capable of maintaining the followability with respect to a preceding vehicle while suppressing the fade phenomenon of the braking device.

[0029] Another aspect of the present invention is a program for causing a computer to execute the travel control of a moving body, which includes acquiring the actual acceleration of the moving body, acquiring the gradient of the travel path on which the moving body travels, detecting a preceding moving body that moves ahead of the moving body, and performing a tracking control to calculate a target acceleration for controlling a propulsion device and a braking device so that the moving body follows the preceding moving body, calculating the target acceleration based on the distance between the moving body and the preceding moving body and a target distance, and starting a suppression control to calculate a corrected target acceleration with the absolute value of the target acceleration decreased when the condition that the magnitude of the downhill gradient of the travel path is equal to or greater than a predetermined gradient determination value and the difference between the target acceleration and the actual acceleration is equal to or less than a predetermined difference determination value is satisfied, and during the execution of the suppression control, the propulsion device and the braking device may be controlled based on the corrected target acceleration instead of the target acceleration.

[0030] According to this aspect, it is possible to provide a program for a computer that can suppress the fade phenomenon of the braking device while maintaining the followability with respect to the preceding vehicle.

Effect of the Invention

[0031] According to the above configuration, it is possible to provide a movement control device, a movement control method, and a program that can suppress the fade phenomenon of the braking device while maintaining the followability with respect to the preceding moving body.

Brief Description of the Drawings

[0032]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0033] Hereinafter, with reference to the drawings, embodiments of the movement control device, the movement control method, and the program according to the present invention will be described. The moving body includes vehicles such as automobiles, trucks, motorcycles, and electric kick scooters. In this embodiment, as an example, an example in which the moving body is a vehicle will be shown.

[0034] As shown in FIG. 1, the vehicle 1 (moving body) has a propulsion device 3, a braking device 4, a steering device 5, an external sensor 6, a vehicle sensor 7, a communication device 8, a navigation device 9, a driving operation device 10, an HMI 12 (Human Machine Interface), and a vehicle control device 15 (movement control device).

[0035] The propulsion device 3 is a device that imparts driving force to the vehicle 1 and includes, for example, a power source and a transmission. The power source has at least one of an internal combustion engine such as a gasoline engine or a diesel engine and an electric motor. The braking device 4 is a device that imparts braking force to the vehicle 1 and includes, for example, a brake caliper that presses a pad against a brake rotor and an electric cylinder that supplies hydraulic pressure to the brake caliper. The braking device 4 may include a parking brake device that restricts the rotation of the wheels by a wire cable. The steering device 5 is a device for changing the steering angle of the wheels and has, for example, a rack and pinion mechanism for steering the wheels and an electric motor for driving the rack and pinion mechanism. The propulsion device 3, the braking device 4, and the steering device 5 are controlled by the vehicle control device 15.

[0036] The external sensor 6 is a sensor that captures electromagnetic waves and light from the periphery of the vehicle 1 and detects objects outside the vehicle, etc. The external sensor 6 includes, for example, a radar 6A, a lidar 6B (LIDAR), and a camera 6C. The external sensor 6 outputs the detection result to the vehicle control device 15.

[0037] The radar 6A emits radio waves such as millimeter waves around the vehicle 1 and detects the position (distance and direction) of an object by capturing the reflected wave. At least one radar 6A is attached to an arbitrary location of the vehicle 1. The radar 6A preferably includes a front radar that irradiates radio waves at least toward the front of the vehicle 1, a rear radar that irradiates radio waves toward the rear of the vehicle 1, and a pair of left and right side radars that irradiate radio waves toward the sides of the vehicle 1.

[0038] The lidar 6B irradiates light such as infrared rays around the vehicle 1 and detects the position (distance and direction) of an object by capturing the reflected light. At least one lidar 6B is provided at an arbitrary location of the vehicle 1.

[0039] Camera 6C images the surroundings of vehicle 1, including objects existing around vehicle 1 (e.g., surrounding vehicles (surrounding moving objects) and pedestrians), guardrails, curbs, walls, median strips, the shape of the road, road markings drawn on the road, etc. Camera 6C may be, for example, a digital camera using a solid-state imaging device such as a CCD or a CMOS. Camera 6C is provided at least one at an arbitrary location of vehicle 1. Camera 6C includes at least a front camera that images the front of vehicle 1, and preferably further includes a rear camera that images the rear of vehicle 1 and a pair of side cameras that image the left and right sides of vehicle 1. Camera 6C may be, for example, a stereo camera.

[0040] Vehicle sensor 7 includes a speed sensor 7A that detects the speed of vehicle 1, an acceleration sensor 7B that detects the acceleration of vehicle 1, and an inclination angle sensor 7C that detects the inclination angle of vehicle 1. Vehicle sensor 7 may include a yaw rate sensor and a steering angle sensor that detects the steering angle of the front wheels which are the steering wheels. Also, vehicle sensor 7 preferably includes a temperature sensor 7D that measures the temperature of the pads of the braking device 4.

[0041] Communication device 8 mediates communication between vehicle control device 15 and navigation device 9 and surrounding vehicles and servers located outside the vehicle. Vehicle control device 15 can perform wireless communication with surrounding vehicles via communication device 8.

[0042] Navigation device 9 is a device that acquires the current position of vehicle 1 and performs route guidance to the destination, and has a GNSS receiving unit 21, a map storage unit 22, a navigation interface 23, and a route determination unit 24. GNSS receiving unit 21 identifies the position (latitude and longitude) of vehicle 1 based on signals received from artificial satellites (positioning satellites). Map storage unit 22 is constituted by a known storage device such as a flash memory or a hard disk and stores map information.

[0043] The map information includes road information such as the types of roads, such as highways, toll roads, national roads, and prefectural roads, the number of lanes of the road, the central position of each lane (3D coordinates including longitude, latitude, and height), the shape of road markings such as road division lines and lane boundaries, the presence or absence of sidewalks, curbs, gutters, etc., the position of intersections, the position of lane merging and branching points, the area of emergency parking areas, the width of each lane, and signs provided on the road. Further, the map information may include traffic regulation information, address information (address and postal code), facility information, telephone number information, etc. The route determination unit 24 determines a route to the destination based on the position of the vehicle 1 identified by the GNSS reception unit 21, the destination input from the navigation interface 23, and the map information. Further, when determining the route, the route determination unit 24 may refer to the positions of lane merging and branching points in the map information and determine the target lane, which is the lane in which the vehicle 1 should travel, as well.

[0044] The driving operation device 10 receives an input operation performed by the driver to control the vehicle 1. The driving operation device 10 includes, for example, a steering wheel, an accelerator pedal, and a brake pedal. Further, the driving operation device 10 may include a shift lever, a parking brake lever, etc. A sensor for detecting the operation amount is attached to each driving operation device 10. The driving operation device 10 outputs a signal indicating the operation amount to the vehicle control device 15.

[0045] The HMI 12 notifies various information to the passengers by display and voice and receives input operations by the passengers. That is, the HMI 12 functions as a notification unit and an input unit.

[0046] The vehicle 1 is provided with a mode change switch 28 that receives an operation for switching the level of autonomous driving.

[0047] The vehicle control device 15 is an electronic control unit (ECU) composed of an MPU (microprocessor), ROM, RAM, etc., that is, a computer. The vehicle control device 15 executes various vehicle controls by the MPU performing arithmetic processing according to a program. The vehicle control device 15 may be configured as one piece of hardware, or may be configured as a unit composed of a plurality of pieces of hardware. Also, at least a part of each functional unit of the vehicle control device 15 may be realized by hardware such as an LSI, ASIC, FPGA, etc., or may be realized by a combination of software and hardware. The program may be stored in a non-volatile storage device such as an HDD or flash memory of the vehicle control device 15, or may be stored in a removable storage medium such as a DVD or CD-ROM, and may be installed in the storage device of the vehicle control device 15 by the storage medium being read by a reading device. Also, the program may be downloaded to and installed in the storage device of the vehicle control device 15 via a communication line such as the Internet. The vehicle control device 15, which is a computer, executes the following-described driving control method for driving control of the vehicle 1. The program causes the vehicle control device 15 to execute driving control of a moving body.

[0048] As shown in FIG. 1, the vehicle control device 15 has an automatic driving control unit 35 and a driving control unit 36. The automatic driving control unit 35 includes an external environment detection unit 40, a host vehicle position detection unit 41, an acceleration acquisition unit 42, a gradient acquisition unit 43, a preceding vehicle detection unit 44 (preceding moving body detection unit), a following control unit 45, a behavior planning unit 46, and a mode switching unit 47.

[0049] The automatic driving control unit 35 performs automatic driving control at each level by combining various vehicle controls. For example, in level 0 automatic driving, the vehicle control device 15 does not control vehicle 1, and the driver performs all driving operations. In level 1 automatic driving, it includes constant speed driving and inter-vehicle distance control (ACC; Adaptive Cruise Control) and lane keeping assistance control (LKA; Lane Keeping Assistance). In levels 2 and 3 of automatic driving, the driver monitors the surroundings of the vehicle, and the vehicle control device 15 performs all driving operations. In levels 2 and 3, the degree of monitoring of the vehicle surroundings by the driver is different.

[0050] The external detection unit 40 detects obstacles located around vehicle 1, the shape of the road, the presence or absence of sidewalks, and road markings based on signals from the external sensor 6. Obstacles include, for example, guardrails, utility poles, surrounding moving objects, and pedestrians such as people. The surrounding moving objects include vehicle 1. The external detection unit 40 may detect the position and distance of obstacles and surrounding vehicles with respect to vehicle 1 based on signals from at least one of the radar 6A, lidar 6B, and camera 6C.

[0051] The own vehicle position detection unit 41 calculates the own vehicle position based on the GNSS signal received by the GNSS reception unit 21. In addition, the own vehicle position detection unit 41 recognizes the driving lane, which is the lane in which vehicle 1 is traveling, and the relative position and angle of vehicle 1 with respect to the driving lane. The own vehicle position detection unit 41 may recognize the driving lane based on, for example, the map information held by the map storage unit 22 and the position of vehicle 1 acquired by the GNSS reception unit 21. In addition, the own vehicle position detection unit 41 may extract the lane lines around vehicle 1 drawn on the road surface from the map information and compare them with the shape of the lane lines imaged by the camera 6C to recognize the relative position and angle of vehicle 1 with respect to the driving lane.

[0052] The acceleration acquisition unit 42 acquires the acceleration (actual acceleration) of vehicle 1 based on the signal from the acceleration sensor 7B.

[0053] The gradient acquisition unit 43 acquires the gradient of the road on which the vehicle 1 travels. The gradient acquisition unit 43 may calculate the gradient of the road based on the inclination angle of the vehicle 1 acquired by the inclination angle sensor 7C. Further, the gradient acquisition unit 43 may search the map information held by the map storage unit 22 based on the position of the vehicle 1 and acquire the gradient of the road. The gradient of the road is set to a positive value when it is an uphill gradient with respect to the traveling direction of the vehicle 1, and a negative value when it is a downhill gradient.

[0054] The preceding vehicle detection unit 44 detects a preceding vehicle 101 that moves ahead of the vehicle 1. The preceding vehicle detection unit 44 determines, for example, the preceding vehicle 101 from among the surrounding vehicles. The preceding vehicle detection unit 44 may determine, for example, a surrounding vehicle that is located on the predicted travel path of the vehicle 1 and within a predetermined distance as the preceding vehicle 101. The preceding vehicle detection unit 44 may calculate the predicted travel path based on at least one of the yaw rate and the steering angle of the vehicle 1 and the speed of the vehicle 1. Further, when there are a plurality of surrounding vehicles that satisfy the conditions as the preceding vehicle 101, the preceding vehicle detection unit 44 may determine the surrounding vehicle with the smallest distance from the vehicle 1 as the preceding vehicle 101.

[0055] The following control unit 45 executes following control to cause the vehicle 1 to follow the preceding vehicle 101. In the following control, the following control unit 45 calculates a target acceleration for controlling the propulsion device 3 and the brake device 4. As shown in FIG. 2, the following control unit 45 sets the target acceleration of the vehicle 1 so that the distance (inter-vehicle distance) between the vehicle 1 and the preceding vehicle 101 approaches the target inter-vehicle distance (target distance). The following control unit 45 may set the target acceleration within a range where the speed of the vehicle 1 becomes equal to or lower than the set vehicle speed. The set vehicle speed may be set by the occupant via the HMI 12 as the upper limit speed during the following control of the vehicle 1. The target inter-vehicle distance may be a preset value or may be set by the occupant via the HMI 12.

[0056] The action planning unit 46 sequentially creates action plans for driving the vehicle 1 along the route. More specifically, the action planning unit 46 first determines an event for driving in the target lane determined by the route determination unit 24 without the vehicle 1 coming into contact with an obstacle. Based on the determined event, the action planning unit 46 generates a target trajectory that the vehicle 1 should follow in the future. The target trajectory is an arrangement of trajectory points, which are the points that the vehicle 1 should reach at each time. The action planning unit 46 may generate the target trajectory based on the target speed and target acceleration set for each event. When the leading vehicle 101 is detected on the target trajectory, the action planning unit 46 may perform follow-up control on the leading vehicle 101 in the same manner as the follow-up control unit 45.

[0057] The mode switching unit 47 switches the level of autonomous driving based on a signal from the mode switch 28. When level 0 is selected by the mode switch 28, the mode switching unit 47 stops the calculations by the follow-up control unit 45 and the action planning unit 46. When level 1 is selected by the mode switch 28, the mode switching unit 47 executes the calculations by the follow-up control unit 45 and stops the calculations by the action planning unit 46. When level 2 or higher is selected by the mode switch 28, the mode switching unit 47 executes the calculations by the action planning unit 46 and stops the calculations by the follow-up control unit 45.

[0058] The driving control unit 36 controls the propulsion device 3, the braking device 4, and the steering device 5 based on the target vehicle speed generated by the follow-up control unit 45. Also, the driving control unit 36 controls the propulsion device 3, the braking device 4, and the steering device 5 so that the vehicle 1 passes through the target trajectory generated by the action planning unit 46 at the scheduled time.

[0059] The following describes the follow-up control executed by the follow-up control unit 45. The follow-up control unit 45 may repeat the follow-up control shown in FIG. 3 at time intervals of, for example, several microseconds. First, the follow-up control unit 45 calculates the target acceleration of the vehicle 1 (S1). The follow-up control unit 45 may calculate the target acceleration based on at least the distance between the vehicle 1 and the preceding vehicle 101 and the target inter-vehicle distance. For example, the follow-up control unit 45 may calculate the target acceleration of the vehicle 1 based on the difference between the distance (actual inter-vehicle distance) between the vehicle 1 and the preceding vehicle 101 and the target inter-vehicle distance, and the relative speed of the preceding vehicle 101 with respect to the vehicle 1. The follow-up control unit 45 may acquire the distance between the vehicle 1 and the preceding vehicle 101 from the external detection unit 40. The follow-up control unit 45 acquires the speed of the vehicle 1 based on the signal from the speed sensor 7A, acquires the speed of the preceding vehicle 101 from the external detection unit 40, and calculates the relative speed between the vehicle 1 and the preceding vehicle 101 based on the speed of the vehicle 1 and the speed of the preceding vehicle 101.

[0060] The follow-up control unit 45 may calculate the target acceleration of the vehicle 1 based on, for example, the following formulas 1 to 3. AT = G1×ΔD + G2×ΔV (Formula 1) ΔD = DR - DT (Formula 2) ΔV = V2 - V1 (Formula 3) Here, AT is the target acceleration [m / s 2 , G1 and G2 are gains, ΔD is the difference between the distance between the vehicle 1 and the preceding vehicle 101 and the target inter-vehicle distance [m], ΔV is the relative speed of the preceding vehicle 101 with respect to the vehicle 1 [m / s], DR is the distance between the vehicle 1 and the preceding vehicle 101 [m] (actual inter-vehicle distance), DT is the target inter-vehicle distance [m], V1 is the speed of the vehicle 1 [m / s], and V2 is the speed of the preceding vehicle 101 [m / s]. Note that the target acceleration is not limited to Formulas 1 to 3 and may be calculated based on various methods.

[0061] Next, the follow-up control unit 45 determines whether the magnitude (absolute value) of the downhill gradient of the road is greater than or equal to a predetermined gradient determination value (S2). The follow-up control unit 45 may acquire the gradient of the road from the gradient acquisition unit 43. The gradient determination value may be set to, for example, 0 to 10 degrees.

[0062] When the downward slope of the traveling road is greater than or equal to the slope determination value (the determination result in step S2 is Yes), the follow-up control unit 45 determines whether the difference between the target acceleration and the acceleration (actual acceleration) of the vehicle 1 is less than or equal to a predetermined difference determination value (S3).

[0063] When the difference between the target acceleration and the acceleration of the vehicle 1 is less than or equal to the difference determination value (the determination result in step S3 is Yes), the follow-up control unit 45 determines whether the target acceleration is a value on the accelerating side, that is, a positive value (S4).

[0064] When the target acceleration is a value on the accelerating side (the determination result in step S4 is Yes), the follow-up control unit 45 sets 1 to the flag F (S5) and executes suppression control (S6). That is, the follow-up control unit 45 starts suppression control when the conditions that the downward slope of the traveling road is greater than or equal to the slope determination value, the difference between the target acceleration and the acceleration of the vehicle 1 is less than or equal to the difference determination value, and the target acceleration is a value on the accelerating side are satisfied. In the suppression control, the follow-up control unit 45 calculates a corrected target acceleration with the absolute value of the target acceleration decreased. The follow-up control unit 45 may calculate the corrected target acceleration by multiplying the target acceleration by a predetermined correction gain. The correction gain may be set to a value greater than 0 and less than 1, for example. Also, the follow-up control unit 45 may calculate the corrected target acceleration by subtracting a predetermined correction amount from the target acceleration. The initial value of the flag F set in step S5 is preferably 0.

[0065] In the suppression control, the follow-up control unit 45 outputs the calculated corrected target acceleration to the travel control unit 36. Then, the travel control unit 36 controls the propulsion device 3 and the brake device 4 based on the corrected target acceleration. That is, while the follow-up control unit 45 is executing the suppression control, the travel control unit 36 controls the propulsion device 3 and the brake device 4 based on the corrected target acceleration instead of the target acceleration.

[0066] When the magnitude of the downhill slope of the traveling road is less than the slope determination value (the determination result in step S2 is No), when the difference between the target acceleration and the acceleration of the vehicle 1 is not less than the difference determination value (the determination result in step S3 is No), or when the target acceleration is not a value on the acceleration increasing side (the determination result in step S4 is No), the follow-up control unit 45 determines whether the flag F is 1 (S7). Step S7 determines whether suppression control was executed in the previous follow-up control.

[0067] When the flag F is 1 (the determination result in step S7 is Yes), the follow-up control unit 45 sets 2 to the flag F (S8), then starts a timer count (S9), and then executes return control (S10). Details of the return control will be described later. The timer count measures the duration of the return control.

[0068] When the flag F is not 1 (the determination result in step S7 is No), the follow-up control unit 45 determines whether the timer count is not less than a predetermined determination value (S11). Step S11 determines whether the duration of the return control has reached a predetermined period based on the timer count. When the timer count is less than the determination value (the determination result in step S11 is No), the follow-up control unit 45 executes return control (S10).

[0069] When the timer count is not less than the determination value (the determination result in step S11 is Yes), the follow-up control unit 45 sets 0 to the flag F (S12), then resets the timer count (S13), and then executes normal control (S14).

[0070] In normal control, the follow-up control unit 45 outputs the calculated target acceleration to the travel control unit 36. Then, the travel control unit 36 controls the propulsion device 3 and the brake device 4 based on the target acceleration.

[0071] In the return control that is executed after the suppression control is stopped, the follow control unit 45 suppresses the change amount of the absolute value of the target acceleration. Thereby, after the suppression control is stopped, a rapid change in the target acceleration is suppressed. Thereby, a rapid change in the acceleration of the vehicle 1 is suppressed. The follow control unit 45 may suppress the change amount of the absolute value of the target acceleration based on the difference between the target acceleration and the acceleration of the vehicle 1 in the return process.

[0072] In the return control, the follow control unit 45 may calculate a second corrected target acceleration calculated by multiplying a return gain by the target acceleration, and output the second corrected target acceleration to the travel control unit 36. Then, the travel control unit 36 may control the propulsion device 3 and the brake device 4 based on the second corrected target acceleration instead of the target acceleration. The return gain is set to a value greater than 0 and less than 1, and greater than the correction gain. Also, the return gain may gradually increase to 1 in response to an increase in the timer count. Thereby, the second corrected target acceleration approaches the target acceleration over time.

[0073] When the follow control unit 45 is executing the suppression control, the HMI 12 may notify the passengers of the vehicle 1 that the suppression control is being executed. When executing the suppression control, the follow control unit 45 outputs a signal to the HMI 12, and the HMI 12 may perform notification by video, image, or voice in response to the signal from the follow control unit 45. Thereby, the passengers can recognize that the suppression control is being executed, and it becomes difficult to feel discomfort.

[0074] When an input operation to the driving operation device 10 that receives the driving operation of the passengers of the vehicle 1 is detected, the follow control unit 45 may stop the suppression control. The driving operation device 10 may be at least one of an accelerator pedal, a brake pedal, and a steering wheel. Thereby, the passengers can stop the suppression control by their own operation.

[0075] When the temperature of the braking device 4 is equal to or higher than a predetermined temperature determination value, the follow-up control unit 45 may stop the follow-up control. The follow-up control unit 45 may acquire the temperature of the pads of the braking device 4 based on the signal from the temperature sensor 7D. Thereby, since the use of the braking device 4 by the follow-up control is stopped, the fade phenomenon is suppressed. Further, the follow-up control unit 45 may stop the follow-up control when the preceding vehicle 101 is no longer the follow-up target.

[0076] The operation and effects of the vehicle control device 15 according to the above embodiment will be described. When the conditions that the magnitude of the downhill gradient of the traveling road is equal to or greater than the gradient determination value, the difference between the target acceleration and the acceleration of the vehicle 1 is equal to or less than the difference determination value, and the target acceleration is a value on the acceleration increasing side are satisfied (the determination results in steps S2, S3, and S4 are all Yes), the follow-up control unit 45 starts the suppression control. In the suppression control, the follow-up control unit 45 calculates a corrected target acceleration whose absolute value is smaller than that of the target acceleration, and the travel control unit 36 controls the propulsion device 3 and the braking device 4 based on the corrected target acceleration instead of the target acceleration. Therefore, the change in the acceleration of the vehicle 1 becomes gentle. As a result, it is suppressed that the distance between the vehicle 1 and the preceding vehicle 101 becomes close, and the use of the braking device 4 is suppressed. As a result, the temperature rise and the fade phenomenon of the braking device 4 are suppressed. When the suppression control is executed, since the difference between the target acceleration and the acceleration of the vehicle 1 is equal to or less than the difference determination value, even if the absolute value of the target acceleration is suppressed, it is suppressed that the distance between the vehicle 1 and the preceding vehicle 101 changes greatly. In particular, when the traveling road is a downhill gradient, an acceleration toward the acceleration increasing side is generated in the vehicle 1 due to gravity. Therefore, even if the target acceleration on the acceleration increasing side is suppressed, the followability of the vehicle 1 with respect to the preceding vehicle 101 is maintained. Thereby, the vehicle control device 15 can maintain the followability with respect to the preceding vehicle 101 while suppressing the fade phenomenon of the braking device 4.

[0077] When the difference between the target acceleration and the acceleration of the vehicle 1 becomes greater than the difference determination value (when the determination result in step S3 is No), the follow-up control unit 45 stops the suppression control. Thereby, the follow-up control unit 45 can maintain the followability with respect to the preceding vehicle 101. When the difference between the target acceleration and the acceleration of the vehicle 1 is greater than the difference determination value, the distance between the preceding moving body and the moving body is likely to change. In such a case, the follow-up control unit 45 stops the suppression control to improve the acceleration responsiveness.

[0078] The follow-up control unit 45 executes the return control for a predetermined period after stopping the suppression control. Thereby, an abrupt increase in the acceleration of the vehicle 1 is suppressed. The follow-up control unit 45 executes the normal control after executing the return control for a predetermined period.

[0079] Although the description of the specific embodiment is finished above, the present invention can be widely modified and implemented without being limited to the above embodiment. In other embodiments, the process of step S4 of the follow-up control may be omitted. In this case, the follow-up control unit 45 may execute the process of step S5 when the determination result of step S3 is Yes, and execute the process of step S7 when the determination result of step S2 or step S3 is No.

Explanation of reference numerals

[0080] 1: Vehicle (moving body) 3: Propulsion device 4: Brake device 5: Steering device 6: External sensor 7: Vehicle sensor 7A: Speed sensor 7B: Acceleration sensor 7C: Tilt angle sensor 7D: Temperature sensor 10: Driving operation device 12: HMI (notification unit) 15: Vehicle control device 28: Mode changeover switch 35: Automatic driving control unit 36: Travel control unit 40: External detection unit 41: Own vehicle position detection unit 42: Acceleration acquisition unit 43: Gradient acquisition unit 44: Preceding vehicle detection unit (preceding moving body detection unit) 45: Follow-up control unit 46: Action planning unit 47: Mode switching unit 101: Preceding vehicle (preceding moving body)

Claims

1. A mobile body control device for controlling the travel of a mobile body, comprising: an acceleration acquisition unit that acquires the actual acceleration of the mobile body; a gradient acquisition unit that acquires the gradient of the travel path on which the mobile body travels; a preceding mobile body detection unit that detects a preceding mobile body that moves ahead of the mobile body; a following control unit that executes following control for calculating a target acceleration for controlling a propulsion device and a braking device so that the mobile body follows the preceding mobile body; the following control unit calculates the target acceleration based on the distance between the mobile body and the preceding mobile body and a target distance; when the condition that the magnitude of the downhill gradient of the travel path is equal to or greater than a predetermined gradient determination value and the difference between the target acceleration and the actual acceleration is equal to or less than a predetermined difference determination value is satisfied, start suppression control for calculating a corrected target acceleration with the absolute value of the target acceleration decreased; A mobile body control device in which, while the following control unit is executing the suppression control, the propulsion device and the braking device are controlled based on the corrected target acceleration instead of the target acceleration.

2. The mobile body control device according to claim 1, wherein the following control unit starts the suppression control when the condition that the magnitude of the downhill gradient of the travel path is equal to or greater than a predetermined gradient determination value, the difference between the target acceleration and the actual acceleration is equal to or less than the predetermined difference determination value, and the target acceleration is a value on the acceleration increasing side is satisfied.

3. The mobile body control device according to claim 1, wherein the following control unit stops the following control when the temperature of the braking device is equal to or higher than a predetermined temperature determination value.

4. The mobile body control device according to claim 1, wherein the following control unit calculates the target acceleration so that the distance between the mobile body and the preceding mobile body approaches the target distance.

5. The mobile body control device according to claim 1, wherein the following control unit stops the suppression control when the difference between the target acceleration and the actual acceleration becomes greater than the difference determination value.

6. The mobile body control device according to claim 1, wherein the following control unit stops the suppression control when an input operation to a driving operation device that receives a driving operation of an occupant of the mobile body is detected.

7. The mobile body control device according to claim 1, wherein the following control unit stops the following control when the preceding mobile body is no longer a following target.

8. The moving body control device according to any one of claims 5 to 7, wherein the following follow-up control unit executes a return process for suppressing a change amount of an absolute value of the target acceleration after the suppression control is stopped.

9. The moving body control device according to claim 8, wherein in the return process, the follow-up control unit suppresses the change amount of the absolute value of the target acceleration based on a difference between the target acceleration and the actual acceleration.

10. The moving body control device according to any one of claims 1 to 7, further comprising a notification unit configured to notify an occupant of the moving body that the suppression control is being executed when the follow-up control unit executes the suppression control.

11. A moving body control method executed by a computer to control traveling of a moving body, the method comprising: acquiring an actual acceleration of the moving body; acquiring a gradient of a traveling path on which the moving body travels; detecting a preceding moving body that moves ahead of the moving body; executing a follow-up control for calculating a target acceleration for controlling a propulsion device and a brake device so that the moving body follows the preceding moving body; calculating the target acceleration based on a distance between the moving body and the preceding moving body and a target distance; starting a suppression control for calculating a corrected target acceleration with a decreased absolute value of the target acceleration when a condition that a magnitude of a downward gradient of the traveling path is equal to or greater than a predetermined gradient determination value and a difference between the target acceleration and the actual acceleration is equal to or less than a predetermined difference determination value is satisfied; A moving body control method, wherein while the suppression control is being executed, the propulsion device and the brake device are controlled based on the corrected target acceleration instead of the target acceleration.

12. A program for causing a computer to execute traveling control of a moving body, the program causing the computer to: acquire an actual acceleration of the moving body; acquire a gradient of a traveling path on which the moving body travels; detect a preceding moving body that moves ahead of the moving body; execute a follow-up control for calculating a target acceleration for controlling a propulsion device and a brake device so that the moving body follows the preceding moving body; calculate the target acceleration based on a distance between the moving body and the preceding moving body and a target distance; start a suppression control for calculating a corrected target acceleration with a decreased absolute value of the target acceleration when a condition that a magnitude of a downward gradient of the traveling path is equal to or greater than a predetermined gradient determination value and a difference between the target acceleration and the actual acceleration is equal to or less than a predetermined difference determination value is satisfied; A program in which, while the suppression control is being executed, the propulsion device and the brake device are controlled based on the corrected target acceleration instead of the target acceleration.

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