Parking assistance device

Abstract

A parking assistance device has a parking assistance control device mounted on a host vehicle, configured to receive an operation signal in a state where a driver has gotten off the host vehicle, and perform parking assistance control to move the host vehicle along a movement path in accordance with the received operation signal. The parking assistance control device controls the drive device and the foot brake device to cause the host vehicle to travel at a speed at which a gear position can be switched to a parking gear position. The parking assistance control device can perform a gear position switching process during execution of the parking assistance control, and switch the gear position after causing the parking brake device to operate to apply a braking force to the wheels in a case where a switching target of the gear position is a gear position other than the parking gear position.

Description

TECHNICAL FIELD

[0001] The present application relates to a parking assistance device that performs parking (stopping) assistance control for causing a vehicle to park in and / or out of a predetermined place. BACKGROUND

[0002] In the past, a parking assistance device has been proposed that detects a target object (a target) around a vehicle using a "camera, a sensor, or the like" around the vehicle, determines a parking area based on the detected target object, and performs parking assistance control for causing the vehicle to autonomously travel to the parking area (for example, refer to German Patent 102015209976).

[0003] According to the device proposed in German Patent 102015209976 (hereinafter referred to as the "conventional device"), it is possible to perform parking assistance control in a state in which the driver has gotten out of the vehicle. This control is also referred to as "remote parking assistance control". When the driver operates a remote controller from outside the vehicle, the remote controller transmits a signal corresponding to the operation of the driver to an ECU of the vehicle via a wireless communication line. The ECU, upon receiving the signal, determines whether various devices (an engine, a brake, a power supply device, and the like) for causing the vehicle to autonomously travel to a predetermined parking area are normal. Moreover, the ECU starts causing the vehicle to autonomously travel in a case in which all of the determined devices are normal. SUMMARY

[0004] Here, after the conventional device starts causing the vehicle to travel to the parking area, the brake device of the vehicle can possibly become abnormal before the vehicle reaches the parking area. Even in such a situation, it is necessary to brake the vehicle, but the conventional device does not have a corresponding means.

[0005] An object of the present application is to provide a parking assistance device that can improve the safety of a vehicle in remote parking assistance control.

[0006] To achieve the above object, a parking assistance device (1) of the present application includes:

[0007] a drive device (20) that applies a driving force to a driving wheel among wheels of a host vehicle;

[0008] a foot brake device (32) and a parking brake device (33) that apply a braking force to the wheels;

[0009] a gear shift device (40) that shifts a gear (a shift position) of a transmission of the host vehicle to one of a plurality of gears including a forward gear (DP), a reverse gear (RP), and a parking gear (PP);

[0010] a steering device (50) that controls a steering angle of a steered wheel among the wheels; and

[0011] The parking assistance control device (10) mounted on the host vehicle is configured to receive an operation signal generated from a portable device (70) operated by the driver through a wireless communication line in a state where the driver has gotten out of the host vehicle, and to execute a parking assistance control that controls the drive device, the foot brake device, the gear shift device, and the steering device so that the host vehicle moves along a movement path that enables the vehicle to move from a position of the host vehicle at a current time to a predetermined target position, in accordance with the received operation signal.

[0012] The parking assistance control device is configured to,

[0013] During execution of the parking assistance control, a gear shift processing that shifts the gear is executable,

[0014] In the gear shift processing, in a case where a shift target of the gear is a gear other than the parking gear, the parking brake device is caused to operate to apply a braking force to the wheels before the gear is shifted.

[0015] In the existing device, there is a case where, in the middle of shifting the gear to, for example, the forward gear or the reverse gear in the remote parking assistance control, the foot brake device can be abnormal. In this case, the vehicle can unintentionally excessively advance or retreat due to a slope (a posture of the vehicle with respect to the horizontal plane (a difference in height between the front end and the rear end of the vehicle)), a crawling phenomenon, or the like. In the parking assistance device according to the present invention, the parking brake is operated to brake the vehicle before starting the shift to a gear other than the parking gear. Therefore, even if the foot brake is abnormal at the time of the shift of the gear as described above, the vehicle can be prevented from unintentionally excessively advancing or retreating. Thus, with the parking assistance device according to the present invention, it is possible to improve the safety of the vehicle in the remote parking assistance control.

[0016] In the parking assistance device according to an embodiment of the present invention,

[0017] The parking assistance control device is configured to, in the gear shift processing, in a case where the shift to any one of the shift from the forward gear to the reverse gear, the shift from the reverse gear to the forward gear, and the shift from the parking gear to another gear is started, the gear is shifted after the parking brake device is caused to operate to apply a braking force to the wheels in a case where a slope (a) is equal to or greater than a predetermined threshold (a th).

[0018] Sometimes, while the gear switching device is switching from its current gear to another gear (the first gear), a command to switch to a second gear, different from the first gear, is sent from the parking assist control unit to the gear switching device. For example, when a malfunction occurs in the foot brake system, a command such as the one described above is sent to brake the vehicle. However, like conventional gear switching devices, the gear switching device of the present invention cannot cancel the switch to the first gear and switch to the second gear. For example, even if an emergency gear switching command such as the one described above is sent while the gear is switching to the forward or reverse gear, the gear switching device will not switch to the parking gear PP until the switch to the forward or reverse gear is completed. Therefore, it takes a long time for the switch to the parking gear PP to be completed. For example, suppose that a malfunction occurs in the foot brake system while the gear is switching to the forward or reverse gear on a vehicle with a relatively steep slope (e.g., a height difference between the front and rear ends of the vehicle) using a conventional device. In this case, the parking assist control device is ready to immediately begin the shift to the parking position. However, as mentioned above, this process takes a considerable amount of time to complete. During this time, the vehicle's own weight may cause it to accelerate toward the lower side of the slope (the lower slope), causing the vehicle speed to exceed the upper limit for shifting to the parking position. In this case, the gear cannot be switched to the parking position. Furthermore, if a shift switching device with a fast shifting speed is used, the shift to the parking position may be completed before the vehicle speed exceeds the upper limit. However, such shift switching devices are generally expensive.

[0019] According to the parking assistance device of the present invention, even if a malfunction occurs with the foot brake while the vehicle is switching gears to forward or reverse on a relatively steep slope, the foot brake releases the vehicle's braking, and the parking brake still applies the brakes. That is, the vehicle does not move forward or backward toward the side with the lower slope. Thus, even if the switch to parking gear takes some time, the switch to parking gear PP can be completed reliably. Thus, the vehicle is braked not only by the parking brake but also by the transmission (the pin restricts the rotation of the gear). Therefore, the parking assistance device of this technical solution can improve the safety of vehicles under remote parking assistance control. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Hereinafter, features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described with reference to the accompanying drawings, in which like reference numerals represent like elements, and wherein:

[0021] Figure 1 This is a block diagram of a parking assistance device according to one embodiment of the present invention.

[0022] Figure 2Ais a plan view (two-dimensional map) showing a movement path (1st path) at the time of entry.

[0023] Figure 2B is a plan view (two-dimensional map) showing a movement path (2nd path) at the time of entry.

[0024] Figure 3 is a table showing a travel plan (travel plan) at the time of entry.

[0025] Figure 4 is a flowchart of a travel plan advancing program.

[0026] Figure 5 is a flowchart of a gear shift program.

[0027] Figure 6A is a plan view (two-dimensional map) showing a movement path (1st path) at the time of exit.

[0028] Figure 6B is a plan view (two-dimensional map) showing a movement path (2nd path) at the time of exit.

[0029] Figure 7 is a table showing a travel plan at the time of exit. DETAILED DESCRIPTION

[0030] <Configuration>

[0031] An embodiment of the present application relates to a parking assistance device 1 for a vehicle. In order to distinguish from other vehicles, the vehicle equipped with the parking assistance device 1 is sometimes referred to as "own vehicle". As shown in FIG. 1, the parking assistance device 1 is provided with a parking assistance ECU 10, a drive device 20, a brake device 30, a gear shift device 40, a steering device 50, a surrounding sensor 60, and a portable device 70. Figure 1

[0032] The parking assistance ECU 10 is provided with a microcomputer including a CPU 10a, a RAM 10b, a ROM 10c, and the like. In addition, in the present specification, "ECU" means an electronic control device (Electronic Control Unit) having a microcomputer including a CPU, a RAM, a ROM, and the like. The CPU realizes various functions by executing instructions stored in the ROM.

[0033] The parking assistance ECU 10 is connected to other ECUs (an engine ECU 21, a brake ECU 31, an SBW ECU 41, and an EPS ECU 51 described later) via a CAN (Controller Area Network) so as to be able to transmit and receive information to and from each other.

[0034] ​Furthermore, the parking assist ECU 10 includes a communication device 10d. The communication device 10d is configured to be able to transmit and receive information to and from a portable device 70 described later via a wireless communication line.

[0035] The drive device 20 generates a driving force and applies the driving force to the driving wheels among the wheels (left front wheel, right front wheel, left rear wheel and right rear wheel). The drive device 20 includes an engine ECU 21, an engine actuator (engine Act) 22, an internal combustion engine 23, a transmission 24, a driving force transmission mechanism (not shown) that transmits the driving force to the wheels, etc. The engine ECU 21 is connected to the engine actuator 22. The engine actuator 22 includes a throttle valve actuator that changes the opening of the throttle valve of the internal combustion engine 23. The engine ECU 21 can change the torque generated by the internal combustion engine 23 by driving the engine actuator 22. The torque generated by the internal combustion engine 23 is transmitted to the driving wheels via the transmission 24 and the driving force transmission mechanism (for example, a drive shaft). As described above, the engine ECU 21 controls the driving force of the vehicle by controlling the engine actuator 22.

[0036] In addition, when the vehicle to which the parking assistance system 1 is applied is a hybrid vehicle (HEV, PEHV) or an electric vehicle (EV) with a transmission, the engine ECU 21 can control the driving force of the vehicle generated by either or both of the "internal combustion engine and electric motor" as the vehicle driving source.

[0037] The brake device 30 applies braking force to the wheels and includes a brake ECU 31, a foot brake mechanism 32, and a parking brake mechanism 33. The brake ECU 31 is connected to the foot brake mechanism 32 and the parking brake mechanism 33 to control the two mechanisms.

[0038] The foot-operated brake mechanism 32 includes a hydraulic circuit 321 and a brake caliper 322. The hydraulic circuit 321 includes an oil reservoir, an oil pump, various valve devices, a hydraulic sensor, etc., which are not shown in the figure. The brake caliper 322 is a hydraulic actuator having a cylinder and a piston. When oil is supplied to the cylinder, the piston is pushed out of the cylinder. A brake pad (brake pad) is provided at the front end of the piston, and the brake pad is pressed against the brake disc. The hydraulic circuit 321 adjusts the hydraulic pressure in the cylinder of the brake caliper 322 according to instructions from the brake ECU 31. As a result, the braking force of the brake caliper 322 on the wheel (brake disc) is controlled. The brake ECU 31 mainly controls the hydraulic circuit 321 to control the braking force of the vehicle when the vehicle is traveling.

[0039] The parking brake mechanism 33 includes an electric motor 331 and a brake caliper 332. The brake caliper 332 is an electric actuator provided with a power conversion mechanism that converts the rotational motion of the output shaft of the electric motor 331 into linear motion. Electric power is supplied to the electric motor 331, and the output portion of the power conversion mechanism moves linearly toward the brake disc (or drum). A brake pad is provided at the front end of the output portion, and the brake pad is pressed against the brake disc (or drum). The brake ECU 31 controls the electric power supplied to the electric motor 331. Thus, the brake force of the brake caliper 332 against the wheels (brake disc (or drum)) is controlled. The brake ECU 31 mainly controls the electric power supplied to the electric motor 331 to control the brake force of the vehicle at the time of parking.

[0040] The gear shift device 40 shifts the gears of the transmission 24. In the present example, the gears include a parking range PP, a forward range DP, and a reverse range RP. In the parking range PP, a pin is engaged with a predetermined gear among the plurality of gears that make up the transmission 24. Therefore, the drive shaft and the drive wheels cannot rotate. That is, in this state, the vehicle is braked. In the forward range DP, the drive force of the drive device 20 is transmitted to the drive shaft and the drive wheels as a drive force for propelling the vehicle forward. In the reverse range RP, the drive force of the drive device 20 is transmitted to the drive shaft and the drive wheels as a drive force for propelling the vehicle backward.

[0041] The gear shift device 40 includes an SBW (Shift-by-Wire) ECU 41, an SBW actuator (SBW Act) 42, a gear shift mechanism 43, and the like. The SBW ECU 41 is connected to the SBW actuator 42. The SBW actuator 42 controls the gear shift mechanism 43 according to a gear shift instruction from the SBW ECU 41, and shifts the gears of the transmission 24.

[0042] The steering device 50 controls the steering angle of the steered wheels (the front left wheel and the front right wheel) of the vehicle. The steering device 50 includes an electric power assisted steering ECU (hereinafter referred to as an "EPS ECU") 51, an assist motor (M) 52, and a steering mechanism 53. The EPS ECU 51 is connected to the assist motor 52 (a drive circuit of the assist motor 52). The assist motor 52 is assembled to the steering mechanism 53. The steering mechanism 53 is a mechanism for steering the steered wheels in accordance with the rotational operation of a steering wheel SW. The steering mechanism 53 includes the steering wheel SW, a steering shaft US that is linked to the steering wheel SW, and a not-shown steering gear mechanism, and the like. The EPS ECU 51 detects the steering torque that the driver inputs to the steering wheel SW by a steering torque sensor (not shown) provided to the steering shaft US, and drives the assist motor 52 on the basis of the steering torque. The EPS ECU 51 applies a steering torque (a steering assist torque) to the steering mechanism 53 by the driving of the assist motor 52, and thus, it is possible to assist the steering operation of the driver.

[0043] Additionally, during the execution of remote parking assist control (described later), the EPS ECU 51 receives a steering command from the parking assist ECU 10 via the CAN. The EPS ECU 51 drives the assist motor 52 based on the steering torque determined by the steering command. This steering torque, unlike the steering assist torque applied to assist the driver's steering described above, is torque applied to the steering mechanism 53 based on the steering command from the parking assist ECU 10 without requiring the driver to steer. This torque changes the steering angle (i.e., the steering angle) of the vehicle's steered wheels.

[0044] The surrounding sensor 60 acquires vehicle surrounding information, including information about three-dimensional objects around the vehicle and information about road markings around the vehicle. Three-dimensional objects include moving objects such as cars, pedestrians, and bicycles, and fixed objects such as guardrails and fences.

[0045] The surrounding sensors 60 include a radar sensor 61, an ultrasonic sensor 62, and a camera 63. The vehicle need not include all of the radar sensor 61, the ultrasonic sensor 62, and the camera 63 as devices for acquiring information about the vehicle's surroundings; it only needs to include at least one of the radar sensor 61, the ultrasonic sensor 62, and the camera 63.

[0046] The radar sensor 61 includes a radar transceiver and a signal processing unit (not shown). The radar transceiver transmits millimeter-wave radio waves (hereinafter referred to as "millimeter waves") toward the vehicle's surrounding area and receives millimeter waves reflected by three-dimensional objects within the transmission range (i.e., reflected waves). The signal processing unit obtains information indicating the distance between the vehicle and the three-dimensional object, the relative speed between the vehicle and the three-dimensional object, and the relative position (or direction) of the three-dimensional object relative to the vehicle based on the phase difference between the transmitted millimeter waves and the received reflected waves, the attenuation level of the reflected waves, and the time from transmitting the millimeter waves to receiving the reflected waves. This information is then output to the parking assist ECU 10.

[0047] The ultrasonic sensor 62 transmits ultrasonic pulses to a predetermined area around the vehicle and receives waves reflected from three-dimensional objects. Based on the time from transmission of the ultrasonic wave to reception of the reflected wave, the ultrasonic sensor can detect the point on the three-dimensional object where the transmitted ultrasonic wave is reflected (i.e., the reflection point) and the distance between the ultrasonic sensor and the three-dimensional object.

[0048] The camera 63 is a digital camera with a built-in CCD (charge coupled device) or CIS (CMOS image sensor) imaging element. The camera 63 outputs image data of the vehicle's surrounding area at a predetermined frame rate. The camera 63 captures the surrounding area of ​​the vehicle, which should be checked when the vehicle enters or exits the parking space, and outputs the resulting image data to the parking assist ECU 10.

[0049] Furthermore, the surrounding sensors 60 also include a vehicle speed sensor 64. The vehicle speed sensor 64 includes a wheel speed sensor. Each time a wheel of the host vehicle rotates a predetermined angle, the wheel speed sensor generates a pulse signal (wheel pulse signal). The vehicle speed sensor 64 measures the number of pulses per unit time in the wheel pulse signal transmitted from the wheel speed sensor. Based on this count, the vehicle speed (wheel speed) of each wheel is calculated. The vehicle speed Vs (actual vehicle speed) is then calculated based on the wheel speed of each wheel. The vehicle speed sensor 64 transmits data indicating the vehicle speed Vs to the parking assist ECU 10.

[0050] In addition, the surrounding sensors 60 also include a tilt sensor 65. The tilt sensor 65 is comprised of, for example, an acceleration sensor that detects acceleration in the vehicle's longitudinal, lateral, and vertical directions. The tilt sensor 65 calculates the slope α based on the acceleration detected by the acceleration sensor. The tilt sensor 65 transmits data representing the slope α to the parking assist ECU 10. The slope α, for example, corresponds to "the height difference between the midpoint of the line segment connecting the centers of the left and right front wheels and the midpoint of the line segment connecting the centers of the left and right rear wheels." If the midpoint on the front side is higher than the midpoint on the rear side, the slope α is a positive value; if the midpoint on the front side is lower than the midpoint on the rear side, the slope α is a negative value.

[0051] The parking assist ECU 10 receives detection signals from the radar sensor 61 and the ultrasonic sensor 62 respectively every time a predetermined time (for convenience, also referred to as the "first predetermined time" in the following description) has passed. The parking assist ECU 10 draws the information contained in the detection signal (i.e., the position of the point where the millimeter wave is reflected, i.e., the position of the reflection point, and the position of the point where the ultrasonic wave is reflected, i.e., the position of the reflection point) on a two-dimensional map. The two-dimensional map is a plan view with the position of the vehicle as the origin, the forward direction of the vehicle as the X-axis, and the left direction of the vehicle as the Y-axis. In addition, the "position of the vehicle" refers to the predetermined center position (e.g., the center of gravity) of the vehicle in the top view. Based on the shape formed by a group of reflection points in the two-dimensional map, the parking assist ECU 10 detects three-dimensional objects located around the vehicle and determines the position (distance and orientation) and shape of the three-dimensional object relative to the vehicle.

[0052] Furthermore, the parking assist ECU 10 acquires image data from the camera 63 every time the first predetermined time period elapses. The parking assist ECU 10 analyzes the image data from the camera 63 to detect three-dimensional objects around the vehicle and determine (detect) the position (distance and orientation) and shape of the three-dimensional objects relative to the vehicle.

[0053] The parking assist ECU 10 adds the information (position and shape) of the identified three-dimensional object to the above-mentioned two-dimensional map.

[0054] The parking assistance ECU 10 parks (or puts the vehicle into a garage) at a location designated by the driver. At this point, the parking assistance ECU 10 detects areas around the vehicle free of three-dimensional objects based on information displayed on a two-dimensional map. If the area free of three-dimensional objects is large and shaped enough for the vehicle to park, the parking assistance ECU 10 determines that area as a "parkable area." Furthermore, if a demarcation line is detected around the vehicle, the parking area is defined as a rectangular area that does not extend beyond the demarcation line, with its long side being greater than the vehicle's overall length (front-to-back length) by a first edge and its short side being greater than the vehicle's overall width (lateral length) by a second edge.

[0055] The parking assist ECU 10 also moves the vehicle from its current parking location to a nearby parking location (pulling the vehicle out of the garage) and waits until the driver gets in. At this point, the parking assist ECU 10 detects areas around the vehicle where no three-dimensional objects are present based on information displayed on the two-dimensional map. If the area without three-dimensional objects is large and shaped enough for the vehicle to park, the parking assist ECU 10 determines that area as a "waiting area."

[0056] The portable device 70 is, for example, a smartphone. Software for remote parking assist control (hereinafter referred to as the "remote parking application") is installed in the portable device 70. With the remote parking application activated, the driver can operate the portable device 70 (touch panel) to transmit a signal (hereinafter referred to as the "propulsion permission signal") to the parking assist ECU 10 via a wireless communication link, instructing the vehicle to move forward or backward when entering or exiting a parking space. Furthermore, the portable device 70 can receive a display signal from the parking assist ECU 10 via a wireless communication link and, based on this display signal, display various information related to remote parking assist control.

[0057] Remote Parking Assist

[0058] (Operation of the Parking Assistance Device 1 During Parking)

[0059] The process of parking the vehicle into the parking area by the parking assistance device 1 is described. The driver drives the vehicle to the destination and stops the vehicle near the place where he intends to park. That is, the driver operates the operating member (lever) to operate the parking brake mechanism 33 and switches the gear to the parking gear PP. Next, the driver starts the remote parking application installed on the portable device 70. When the remote parking application is started, an image (mode selection icon) for selecting any one of the parking mode and the exit mode is displayed on the portable device 70. When the driver selects the parking mode (clicks the icon), data representing the two-dimensional map and the parking area is sent from the parking assistance ECU 10 to the portable device 70. In addition, asFigure 2A As shown, the portable device 70 displays the parking area (in Figure 2A (The dotted area is shown in the figure). In this figure, there is only one parking area, but there may be multiple parking areas.

[0060] When the driver selects a parking area (by clicking an image of the parking area), the parking assist ECU 10 determines the area occupied by the vehicle if the vehicle were to be parked in the parking area as the "parking area." Furthermore, the parking assist ECU 10 determines the vehicle's position (the center position of the vehicle in a top-down view) when the vehicle is parked in the parking area as the "parking position."

[0061] Next, the parking assist ECU 10 creates a "travel plan" that indicates the vehicle's travel strategy from the initial position P0 to the parking position PK. Figure 3 As shown, the driving plan includes a movement path, a gear shift pattern, a speed pattern, and a steering angle pattern.

[0062] The movement path is a path that allows the vehicle to move from the initial position P0 to the parking position PK while maintaining a predetermined distance from the vehicle body to three-dimensional objects (such as other vehicles, curbs, and guardrails). For example, the parking assist ECU 10 calculates multiple target positions P1, P2, and so on between the initial position P0 and the parking position PK (the final target position). The parking assist ECU 10 controls other ECUs so that the vehicle, starting from the initial position P0, sequentially passes through the target positions P1, P2, and so on, ultimately reaching the parking position PK.

[0063] Here, when the vehicle cannot be moved to the parking position PK by moving the vehicle forward or backward only once from the initial position P0, the parking assist ECU 10 calculates the movement path as follows. Figure 2A 、 2B and Figure 3 As shown, the parking assist ECU 10 calculates a target position Px (P5 in the example shown in the figure) for switching the travel direction from the initial position P0. Specifically, in the example shown in the figure, target position P5 is the position at which the vehicle is temporarily stopped in order to switch the gear position of the transmission 24 from forward gear DP to reverse gear RP. Furthermore, the ECU 10 calculates a first movement path (P0 to P5) for advancing the vehicle to target position P5 and a second movement path (P5 to PK) for reversing the vehicle from target position P5 to parking position PK. While the figure illustrates a single direction switch, if multiple direction switches are required, the parking assist ECU 10 calculates multiple target positions for switching the travel direction.

[0064] The shift pattern is data that associates a target position with a gear position and indicates the changes in gear position as the vehicle travels along its path. The parking assist ECU 10 transmits a shift control command to the SBW ECU 41 via the CAN according to the determined shift pattern. Upon receiving the shift control command from the parking assist ECU 10, the SBW ECU 41 drives the SBW actuator 42 to change the gear position of the transmission 24 to the position specified by the shift control command (i.e., executes gear switching control).

[0065] The steering angle pattern is data that associates a target position with a steering angle, representing changes in the steering angle as the vehicle travels along its path. Based on the determined steering angle pattern, the parking assist ECU 10 transmits a steering command (including the target steering angle) to the EPS ECU 51 via the CAN. Upon receiving the steering command from the parking assist ECU 10, the EPS ECU 51 drives the assist motor 52 based on the steering torque determined by the steering command to bring the actual steering angle into alignment with the target steering angle (i.e., performs steering angle control).

[0066] The speed pattern is data that associates a target position with a driving speed, and indicates changes in the driving speed of a vehicle as it travels on a moving path. The parking assist ECU 10 sends a driving force control instruction to the engine ECU 21 via the CAN according to the determined speed pattern. When the engine ECU 21 receives the driving force control instruction from the parking assist ECU 10, it controls the engine actuator 22 according to the driving force control instruction (i.e., performs driving force control). Furthermore, the parking assist ECU 10 sends a braking force control instruction to the brake ECU 31 according to the determined speed pattern. When the brake ECU 31 receives the braking force control instruction from the parking assist ECU 10, it controls the hydraulic circuit 321 according to the braking force control instruction (i.e., performs braking force control).

[0067] As mentioned above, when the gear position is Park PP, the pin is locked in a predetermined gear constituting the transmission 24, preventing the drive wheels from rotating. In other words, in this state, even if the foot brake mechanism 32 and the parking brake mechanism 33 are not operating, the vehicle is braked by the action of the transmission 24. When the gear position is switched to Park PP, if the vehicle speed Vs exceeds a predetermined value (the rotational speed of the gears of the transmission 24 exceeds the predetermined value), not only will it be difficult for the pin to lock in the gear, but the pin or gear may also be damaged. Therefore, the transmission 24 is configured to switch the gear position to Park PP only when the vehicle speed Vs is less than or equal to a relatively small upper limit. In this embodiment, the speed pattern is determined so that the maximum vehicle speed Vs during parking is less than or equal to a threshold value VL slightly lower than the aforementioned upper limit (i.e., the vehicle speed Vs during parking is a speed that allows the gear position to be switched to Park PP).

[0068] When the parking assist ECU 10 determines the driving plan, it causes the portable device 70 to display the movement path (initial position P0 (current position), target positions P1, P2, ..., and parking position PK) and an image for starting parking (parking start icon). The driver exits the vehicle and taps the parking start icon. The portable device 70 then displays an image for advancing the driving plan (advance permission icon). The advance permission icon can slide in a predetermined direction (e.g., toward the top of the portable device 70 screen). If the driver repeatedly slides the advance permission icon in the predetermined direction, for example, three or more times per second, the portable device 70 continuously transmits advance permission signals to the parking assist ECU 10 via wireless communication, allowing the advancement of the driving plan. Receiving the advance permission signals, the parking assist ECU 10 controls the vehicle according to the driving plan. If the driver temporarily stops sliding the advance permission icon before the vehicle reaches parking position PK, the portable device 70 stops transmitting the advance permission signals. Consequently, the parking assist ECU 10 temporarily stops advancing the driving plan. In other words, the parking assist ECU 10 stops the vehicle. Specifically, the parking assist ECU 10 activates the foot brake mechanism 32 via the brake ECU 31 to brake the vehicle. Furthermore, if the driver does not slide the propel enable icon (the duration for which the propel enable signal is not transmitted) for a period exceeding a predetermined threshold, the parking assist ECU activates the parking brake mechanism 33 via the brake ECU 31 and activates the SBW actuator 42 via the SBW ECU 41 to shift the gear to the parking position PP. When the driver begins sliding the propel enable icon again, the parking assist ECU 10 resumes the propulsion driving plan. In other words, the parking assist ECU 10 releases the vehicle's brakes and begins driving the vehicle.

[0069] As described above, the parking assist ECU 10 switches gears while executing a driving plan. When the vehicle is braked (stopped) by the foot brake mechanism 32 and about to switch gears, the parking assist ECU 10 determines, immediately before the shift, whether the target gear is a gear other than the parking gear. Specifically, the parking assist ECU 10 determines whether the gear switching pattern matches one of the following patterns.

[0070] (A) From forward gear DP to reverse gear RP

[0071] (B) From reverse gear RP to forward gear DP

[0072] (C) From parking position PP to other positions (DP, RP)

[0073] If the scheduled shift mode matches one of the above modes, the parking assist ECU 10 obtains the slope α from the tilt sensor 65. If the magnitude (absolute value) of the slope α exceeds a predetermined threshold value αth, the parking assist ECU 10 activates the parking brake mechanism 33. After the parking brake mechanism 33 has completed braking the vehicle, the parking assist ECU 10 activates the SBW actuator 42 and the shift switching mechanism 43 to switch the shift to the target position. Furthermore, after the shift is completed, the parking assist ECU 10 releases the parking brake mechanism 33 from braking the vehicle.

[0074] On the other hand, when the shift target is the parking position PP, the parking assist ECU 10 switches the shift position to the parking position PP regardless of the gradient α and simultaneously actuates the parking brake mechanism 33 to brake the vehicle.

[0075] When the parking assist ECU 10 completes the driving plan (i.e., the vehicle arrives at and stops at parking position PK, the parking brake mechanism 33 applies the vehicle brakes, and the gear position is switched to parking position PP), it causes the portable device 70 to display an image indicating that parking is complete (a parking completion icon). When the driver clicks the parking completion icon, the parking assist ECU 10 stops the engine. Furthermore, the portable device 70 terminates execution of the parking assist application.

[0076] Furthermore, while executing the driving plan, the parking assist ECU 10 monitors whether the foot brake mechanism 32 is operating normally. For example, the parking assist ECU 10 determines whether the foot brake mechanism 32 is operating normally based on the measured values ​​of the hydraulic pressure within the hydraulic circuit, the vehicle speed Vs, and other parameters relative to the command value to the brake ECU 31. For example, if the measured value obtained from the hydraulic pressure sensor is significantly greater or less than the hydraulic pressure assumed for the command value to the brake ECU 31 (the command value that activates the foot brake mechanism 32), the parking assist ECU 10 determines that an abnormality has occurred in the foot brake mechanism 32. Furthermore, if the measured value obtained from the vehicle speed sensor 64 (or its variation) is significantly greater or less than the vehicle speed Vs (or its variation) assumed for the command value to the brake ECU 31, the parking assist ECU 10 determines that an abnormality has occurred in the foot brake mechanism 32.

[0077] When determining that an abnormality has occurred in the foot brake mechanism 32 , the parking assist ECU 10 immediately switches the shift position to the parking position PP and simultaneously actuates the parking brake mechanism 33 to brake the vehicle.

[0078] Next, refer to Figure 4 , a process in which the CPU of the parking assist ECU 10 (hereinafter referred to as “CPU”) advances the driving plan will be described in detail.

[0079] When the driver clicks the parking start icon, the CPU starts executing Figure 4 The driving plan advancement program shown. The CPU starts the driving plan advancement process from step 400. Then, in step 401, the CPU determines whether the advancement of the driving plan is permitted. In the case of receiving an advancement permission signal from the portable device 70, the CPU determines that "the advancement of the driving plan is permitted" (step 401: yes), and proceeds to step 402. Then, in step 402, the CPU advances the driving plan. That is, for example, the CPU moves the vehicle to the next target position. In addition, for example, the CPU switches the gear. When a predetermined time has passed after the CPU starts step 402, it proceeds to step 403.

[0080] Next, in step 403, the CPU determines whether the vehicle has arrived at the parking position PK. If the vehicle has arrived at the parking position PK (step 403: Yes), the CPU ends the driving plan advancement process in step 404. On the other hand, if the vehicle has not arrived at the parking position PK (step 403: No), the CPU returns to step 401.

[0081] If the CPU does not receive a propulsion permission signal from the portable device 70 in step 401, it determines that "propulsion of the driving plan is prohibited" (step 401: No) and proceeds to step 405. Then, in step 405, the CPU temporarily suspends propulsion of the driving plan. Specifically, the CPU activates the foot brake mechanism 32 (and the parking brake mechanism 33) to brake the vehicle and then returns to step 401.

[0082] When the driving plan is allowed to proceed, the CPU makes the SBW ECU 41 switch the gear according to the gear shift pattern. That is, the CPU refers to the gear shift pattern and executes the shift control when it detects that the vehicle has reached the position where the gear is to be changed. Figure 5 In addition, even if the foot brake mechanism 32 has an abnormality, the CPU also executes Figure 5 Gear shifting procedure shown.

[0083] The CPU starts the shift switching process at step 500. Next, at step 501, the CPU determines whether the target shift position is a shift position other than the parking position PP. If the target shift position is a shift position other than the parking position PP (step 501: YES), the CPU proceeds to step 502.

[0084] Next, in step 502 , the CPU obtains data indicating the gradient α from the tilt sensor 65 and determines whether the magnitude (absolute value) of the gradient α is greater than a threshold αth. If the gradient α is greater than the threshold αth (step 502 : YES), the CPU proceeds to step 503 .

[0085] Next, in step 503, the CPU determines whether the parking brake mechanism 33 has released the brake on the vehicle. If the parking brake mechanism 33 has released the brake on the vehicle (step 503: Yes), the CPU proceeds to step 504, operates the parking brake mechanism 33, brakes the vehicle, and proceeds to step 505.

[0086] After entering step 505, the CPU causes the SBW ECU 41 to switch the gear to the target position (a gear other than the parking gear PP). Then, in step 506, the CPU releases the parking brake mechanism 33 from braking the vehicle. In step 507, the CPU ends the gear switching process and returns to the main routine (e.g. Figure 4 ).

[0087] If the target shift position is the parking position PP in step 501 (step 501: No), the CPU proceeds to step 508, where it switches the shift position to the target shift position (parking position PP) and simultaneously actuates the parking brake mechanism 33 to brake the vehicle. The CPU then proceeds to step 507.

[0088] If the gradient α is less than or equal to the threshold αth in step 502, the CPU proceeds directly from step 502 to step 505. Specifically, if the target shift position is a shift position other than the parking position PP and the gradient α is less than or equal to the threshold αth, the CPU switches the shift position without activating the parking brake mechanism 33.

[0089] In addition, when the vehicle has been braked by the parking brake mechanism 33 when the CPU enters step 503 (for example, when switching from the parking gear PP to other gears in order to resume driving from a paused state), there is no need to execute step 504, so the CPU directly proceeds from step 503 to step 505.

[0090] (Operation of the Parking Assistance Device 1 During Parking Exit)

[0091] The following describes the process by which the parking assistance device 1 causes a parked vehicle to exit the garage and park near the driver. When the driver activates the remote parking application installed on the portable device 70 and selects the exit mode (clicks the icon), the parking assistance ECU 10 starts the engine (internal combustion engine 23) of the vehicle. Furthermore, the parking assistance ECU 10 transmits data representing a two-dimensional map and a waiting area to the portable device 70. Figure 6A As shown, the portable device 70 displays the waiting area (in Figure 6A (areas with dots in the middle).

[0092] When the driver selects a waiting area, the parking assist ECU 10 determines the area occupied by the vehicle if the vehicle is parked in the waiting area as the "waiting area." Furthermore, the parking assist ECU 10 sets the vehicle's position (the center position of the vehicle in a top view) when the vehicle is parked in the waiting area as the "waiting position PW."

[0093] The subsequent actions of the parking assist ECU 10 are the same as those during parking. Figure 7 As shown, the parking assist ECU 10 creates a travel plan indicating a travel strategy of the vehicle from the initial position P0 (that is, the position where the vehicle is parked) to the waiting position PW, and drives the vehicle according to the travel plan.

[0094] Effects

[0095] Sometimes, while the gear switching device 40 is switching from the current gear to another gear (the first gear), a command to switch to a second gear, different from the first gear, is sent from the parking assist ECU 10 to the SBW ECU 41. For example, if a malfunction occurs in the foot brake mechanism 32, a command such as the one described above may be sent to brake the vehicle. However, like conventional gear switching devices, the gear switching device 40 of this embodiment cannot cancel the switch to the first gear and switch to the second gear. For example, even if an emergency gear switching command such as the one described above is sent while the gear is switching to the forward gear DP or the reverse gear RP, the gear switching device 40 will not switch to the parking gear PP until the shift to the forward gear DP or the reverse gear RP is complete. Therefore, it takes a long time for the shift to the parking gear PP to be completed. For example, suppose that in a vehicle using a conventional device, a malfunction occurs in the foot brake device while the gear is switching to the forward gear or the reverse gear on a relatively steep slope. In this case, the parking assist ECU immediately sends a command to the gear switching device 40 to switch the gear to the parking gear PP. However, in this case, as mentioned above, since the gear switching to the parking gear must be started after the shift to the forward gear or reverse gear is completed, it takes a long time for the shift to the parking gear PP to be completed. Therefore, before this process is completed, the vehicle may accelerate toward the lower side of the slope due to its own weight, causing the vehicle speed to exceed the upper limit of the speed at which the gear can be switched to the parking gear. In this case, the gear cannot be switched to the parking gear. In addition, if a gear switching device with a fast gear switching speed is used, it is possible to complete the shift to the parking gear before the vehicle speed exceeds the aforementioned upper limit. However, such gear switching devices are generally expensive.

[0096] According to the parking assistance device 1, even if a fault occurs in the foot brake mechanism 32 while the vehicle is being switched to forward gear DP or reverse gear RP on a relatively steep slope, the foot brake mechanism 32 releases the vehicle's brakes, but the parking brake mechanism 33 applies the brakes. In other words, the vehicle does not move forward or backward toward the lower side of the slope. Thus, even if the switch to parking gear PP takes some time, it can be reliably completed. Thus, the vehicle is braked not only by the parking brake mechanism 33 but also by the transmission 24 (the pins restricting gear rotation). Therefore, the parking assistance device 1 can improve vehicle safety during remote parking assistance control.

[0097] In addition, the present invention is not limited to the above-described embodiment, and various modifications can be adopted within the scope of the present invention.

[0098] (Variation)

[0099] When the shift switching target is a shift other than the parking shift, the vehicle may be braked by the parking brake mechanism 33 before starting the shift switching, regardless of the value of the gradient α.

[0100] In conventional devices, there is a possibility that a malfunction may occur in the foot brake mechanism 32 during a gear shift, such as switching to the forward gear DP or the reverse gear RP. In this case, even if the road surface is generally level, the vehicle may inadvertently move forward or backward excessively due to a creeping phenomenon. In the parking assistance device 1 according to this modified example, the parking brake mechanism 33 is activated to brake the vehicle before starting to shift to a gear other than the parking gear PP, regardless of the slope α. Therefore, even if a malfunction occurs in the foot brake mechanism 32 during a gear shift as described above, the vehicle can be prevented from inadvertently moving forward or backward excessively. Thus, the parking assistance device 1 according to this modified example can improve the safety of the vehicle during remote parking assistance control.

Claims

1. A parking assistance device comprising: a driving device for applying a driving force to a driving wheel among the wheels of the vehicle; a foot-operated brake device and a parking brake device for applying braking force to the wheels; a gear shifting device for shifting the gear of the transmission of the vehicle to one of a plurality of gears including a forward gear, a reverse gear, and a parking gear; A steering device for controlling a steering angle of a steering wheel among the wheels; and a parking assist control device mounted on the host vehicle and configured to receive an operation signal generated from a portable device operated by the driver via a wireless communication link while the driver has exited the host vehicle, and to execute parking assist control based on the received operation signal to control the drive device, the foot brake device, the shift switching device, and the steering device so that the host vehicle moves along a movement path that enables the host vehicle to move from a current position of the host vehicle to a predetermined target position. The parking assist control device is configured as follows: During the execution of the parking assist control, a shift switching process for switching the shift position can be executed. In the gear switching process, when any one of switching from the forward gear to the reverse gear, switching from the reverse gear to the forward gear, and switching from the parking gear to another gear is started, When the slope is equal to or greater than a predetermined threshold, the parking brake device is actuated to apply braking force to the wheels, and then the gear position is switched. After the gear position is changed, the parking brake device releases the brake on the vehicle. When the slope is less than the predetermined threshold, the gear is switched without applying the parking brake.

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