WO2024203713A1 - Parking assist system - Google Patents

Abstract

According to the present invention, during execution of a first feedback control (FB1) in which a driving force (F) and a braking force (F) acting on a wheel are controlled to bring an actual speed (Vr) closer to a first target speed (Vt1) on the basis of a difference between the actual speed (Vr) and the first target speed (Vt1), and to bring an actual acceleration (Ar) closer to a first target acceleration (At1) on the basis of a difference between the actual acceleration (Ar) and the first target acceleration (At1), if a brake operation by a driver is detected, a second feedback control (FB2) in which the driving force (F) and the braking force (F) acting on the wheel are controlled using the lower of the first target speed (Vt1) and the actual speed (Vr) as a second target speed Vt2 is executed instead of the first feedback control (FB1).

Description

Parking Assistance System

The present invention relates to a parking assistance system that controls a vehicle to move it into a parking space.

JP 2021-160476 A discloses a parking assistance system that controls the driving force and braking force acting on the wheels to control the vehicle to move it into a parking space. The parking assistance system performs an automatic driving process to move the vehicle, but even when such an automatic driving process is being performed, it is possible to apply a braking force to the wheels when the driver operates the brakes. In the parking assistance system disclosed in the document, when an obstacle is detected to be present around the vehicle, the parking assistance system notifies the driver of the presence of the obstacle. When the driver operates the brakes, the parking assistance system determines whether the brake operation is appropriate, and if appropriate, applies a braking force to the wheels in response to the driver's brake operation, and continues the automatic driving process thereafter. On the other hand, when the parking assistance system determines that the driver's brake operation is not appropriate, the parking assistance system stops the automatic driving process so that it cannot be resumed, or suspends the automatic driving process so that it can be resumed, or continues the automatic driving process while issuing a warning, etc., depending on the location of the obstacle recognized by the parking assistance system.

JP 2021-160476 A

As described above, when control is performed according to the location of an obstacle, the vehicle can be prevented from coming into contact with the obstacle and appropriately controlled. However, the driver does not necessarily operate the brakes during automatic driving by the parking assistance system only when considering contact with an obstacle. For example, the driver may want to stop in a parking lot to see guidance or the like. In such a case, if the parking assistance system determines that there is no obstacle and the automatic driving process continues without decelerating, this may reduce the driver's convenience. In addition, the driver may feel uneasy if the vehicle continues to move without decelerating against his or her will despite the braking operation. On the other hand, if the driver's braking operation is always prioritized when the driver operates the brakes, the parking assistance may be interrupted or stopped, and the vehicle may not be able to be moved appropriately into a parking space, which may reduce the driver's convenience.

In light of the above background, it is desirable to realize a parking assistance system that can move a vehicle into a parking space while appropriately balancing the automatic control of the driving force and braking force acting on the wheels with the braking force exerted by the driver.

In view of the above, the parking assistance system is a parking assistance system equipped with a vehicle control unit that controls the driving force and braking force acting on the wheels to control the vehicle to move the vehicle equipped with the wheels into a parking space, and further includes a brake operation detection unit that detects the brake operation by the driver, a speed detection unit that detects the actual speed of the vehicle, and an acceleration detection unit that detects the actual acceleration of the vehicle, and while the vehicle is moving into the parking space, the vehicle control unit executes a target calculation process to calculate a first target speed and a first target acceleration for moving and stopping the vehicle to the parking target position based on a parking target position set in the parking space and the current position of the vehicle, and A first feedback control is executed to control the driving force and braking force acting on the wheels so as to bring the actual speed closer to the first target speed based on the difference between the actual acceleration and the first target acceleration, and to bring the actual acceleration closer to the first target acceleration based on the difference between the actual acceleration and the first target acceleration. When the brake operation detection unit detects the brake operation by the driver during the execution of the first feedback control, a second feedback control is executed in place of the first feedback control, in which the lower of the first target speed and the actual speed is set as a second target speed, and the driving force and braking force acting on the wheels are controlled based on the difference between the actual speed and the second target speed so as to bring the actual speed closer to the second target speed.

According to this configuration, when the actual speed of the vehicle becomes lower than the target value of the feedback control due to the driver's brake operation while the vehicle is traveling under the vehicle control of the vehicle control unit, the vehicle control unit changes the target value to a lower value in accordance with the actual speed. In other words, the vehicle control unit executes the second feedback control instead of the first feedback control. If the first feedback control is continued even when the actual speed becomes lower than the target value due to the driver's brake operation, the change in speed due to the driver's brake operation may be treated as a disturbance, and the traveling speed may be maintained. However, according to this configuration, the driver's brake operation is recognized as a disturbance, and a driving force in the accelerating direction is not output, so that the feedback control can be appropriately continued, and the vehicle can be prevented from traveling without decelerating against the driver's intention. On the other hand, even if the driver brakes, if the actual speed of the vehicle is higher than the target value of the feedback control, the vehicle control unit maintains the target value. In other words, the vehicle control unit continues to execute the first feedback control. Therefore, even if the driver brakes while the vehicle is traveling under the vehicle control of the vehicle control unit, the vehicle can be appropriately stopped at the parking target position. In this case, the vehicle is decelerated by more than the amount of braking by the driver, so deceleration is achieved in line with the driver's intention. In this way, this configuration realizes a parking assistance system that can move the vehicle into a parking space while appropriately balancing the automatic control of the driving force and braking force acting on the wheels and the braking force caused by the driver's braking operation.

Further features and advantages of the parking assistance system will become apparent from the following description of exemplary, non-limiting embodiments illustrated with reference to the drawings.

FIG. 1 is an explanatory diagram showing an example of parking assistance; FIG. 11 is an explanatory diagram showing another example of parking assistance; FIG. 1 is a schematic block diagram showing an example of a system configuration of a vehicle including a parking assistance system; Schematic control block diagram of vehicle control by a vehicle control unit Block diagram showing an example of feedback control FIG. 1 is a block diagram showing an example of a feedback control system that selectively performs a first feedback control and a second feedback control; A flowchart showing an example of a procedure for selecting the first feedback control and the second feedback control.

Below, an embodiment of the parking assistance system will be described with reference to the drawings. The explanatory diagrams of Fig. 1 and Fig. 2 each illustrate one form of parking assistance when parking the vehicle 50. The block diagram of Fig. 3 shows a schematic example of a system configuration of the vehicle 50 including the parking assistance system 100. The parking assistance system 100 of this embodiment controls the driving force and braking force acting on the wheels W, as well as the steering angle, to perform vehicle control for moving the vehicle 50 to the parking space E. In this embodiment, the parking assistance system 100 parks the vehicle 50 in the parking space E by automatic driving. Note that the parking assistance system 100 may be configured so that the driver manually steers based on guidance from the parking assistance system 100, and only driving and braking are performed by automatic driving, i.e., semi-automatic driving.

As shown in FIG. 3, the parking assistance system 100 is realized by the cooperation of ECU (Electronic Control Unit) 1 with other systems and various sensors. ECU 1 corresponds to a vehicle control unit that controls the vehicle. ECU 1 is configured with a processor 1P such as a microcomputer, microprocessor, or DSP (Digital Signal Processor), a program memory 1M in which software such as programs and parameters are stored, and various other electronic components. Processor 1P is the hardware that is the core of ECU 1, and the vehicle control unit is realized by the cooperation of various hardware with processor 1P as the core and software such as programs stored in program memory 1M. Then, parking assistance system 100 is realized by the cooperation of ECU 1 with other systems such as drive system 20, brake system 30, steering system 40, and various sensors and peripheral devices indicated by symbols "51" to "58". The various functional units that make up the parking assistance system 100 are described below, but each functional unit may be realized by multiple pieces of hardware, or may be realized by the cooperation of at least one piece of hardware and software, and does not necessarily have to be configured as an independent component.

As shown in Figures 1 and 2, the parking assistance system 100 moves and stops the vehicle 50 to the parking target position Pt based on the parking target position Pt set in the parking space E and the current position Pr of the vehicle 50. The parking target position Pt and the current position Pr correspond to coordinates in a coordinate system (parking assistance coordinate system) when the parking assistance system 100 performs parking assistance (vehicle control). The parking assistance coordinate system may be absolute coordinates (world coordinate system) that cover the entire Earth, or a local coordinate system that covers the area around the vehicle 50 or the parking space E, the entire parking lot including the parking space E, or the area including the parking lot.

The symbol "Q" shown in FIG. 1 and FIG. 2 indicates a reference point on the vehicle 50 when identifying the position of the vehicle 50. The current position Pr corresponds to the coordinates where the reference point Q is located in the parking assistance coordinate system. The parking target position Pt indicates the coordinates where the reference point Q of the vehicle 50 is located when the vehicle 50 is appropriately located in the parking space E. The parking assistance system 100 calculates the movement trajectory of the reference point Q when the vehicle 50 moves from the current position Pr to the parking target position Pt based on the current position Pr and the parking target position Pt, and sets this as the movement path K. The parking assistance system 100 controls the vehicle so that the reference point Q moves from the current position Pr along the movement path K. When the reference point Q reaches the parking target position Pt, that is, when the current position Pr and the parking target position Pt coincide with each other, the parking assistance system 100 stops the vehicle 50 because the vehicle 50 is appropriately located in the parking space E.

FIG. 1 illustrates so-called garage parking. For example, the driver passes parking space E, steers the vehicle 50 in the opposite direction to parking space E, and stops the vehicle 50 in a slightly turned position. This position can be called the reverse start position where the vehicle 50 starts to reverse toward the parking space E. Note that, although a large amount of steering is required when moving to the parking target position Pt, the vehicle 50 may be stopped in a straight line as in FIG. 2 without turning the steering wheel in this way. Also, before starting to move from the stop position to the parking target position Pt, the direction of the steering wheels may be changed by so-called stationary steering in cooperation with the steering system 40.

FIG. 2 illustrates so-called parallel parking. In this case, the driver also stops the vehicle 50 by passing the parking space E, for example. Although FIG. 2 illustrates an example of stopping the vehicle 50 without turning the steering wheel, the vehicle 50 may be stopped with the steering wheel turned in the opposite direction to the parking space E, as in FIG. 1.

When the driver drives the vehicle 50 forward, it is preferable that the parking assistance system 100 guides the driver on the direction of travel and the stopping position (reverse start position). For example, it is preferable that the driver is guided by display on a display in the vehicle cabin or by audio guidance, and the driver operates an accelerator pedal, brake pedal, steering wheel, etc. (not shown) to move the vehicle 50 to the reverse start position. In one embodiment, when the vehicle 50 reaches the reverse start position, the parking assistance system 100 notifies the driver that automatic driving, including automatic steering, is possible. When the driver instructs the start of vehicle control, for example by touching a start button provided on a touch panel of a display in the vehicle cabin, the driving operation of the vehicle 50, including steering, is left to the parking assistance system 100, and the parking assistance system 100 moves the vehicle 50 to the parking target position Pt by automatic driving.

Here, an example is shown in which the driver drives the vehicle 50 forward to the reverse start position, but this does not prevent the parking assistance system 100 from executing vehicle control (parking assistance) and driving the vehicle 50 by automatic driving before the vehicle 50 reaches the reverse start position, i.e., before the vehicle 50 starts moving forward toward the reverse start position.

The vehicle control targeted by this embodiment is control for moving the vehicle 50 from the reverse start position to the parking target position Pt. Therefore, the driving assistance system controls the driving force and braking force acting on the wheels W, and preferably also controls the steering angle, to move the vehicle 50 to the parking target position Pt and stop it based on the parking target position Pt set in the parking space E and the current position Pr of the vehicle 50. The reverse start position can be said to be the initial value of the current position Pr of the vehicle 50. As described above, the vehicle control is not limited to a form in which driving, braking, and steering are all performed automatically, but may be semi-automatic driving in which only driving and braking are performed automatically and steering is performed manually by the driver.

In addition, although an example is shown here of moving the vehicle 50 to the parking space E by reversing, this does not preclude moving the vehicle 50 to the parking space E by moving forward. Therefore, the vehicle control that is the subject of this embodiment corresponds to control of moving the vehicle 50 from a position where the vehicle 50 temporarily stopped before starting to move to the parking space E to the parking target position Pt when performing vehicle control by automatic driving without stopping the vehicle 50 at the parking target position Pt. And, this position where the vehicle 50 temporarily stopped can be said to be the initial value of the current position Pr of the vehicle 50.

As shown in the schematic block diagram of FIG. 3, the vehicle 50 includes an ECU 1, which is the core of the parking assistance system 100, as well as a drive system 20, a brake system 30, and a steering system 40. The drive system 20 is a system that controls a drive device 25 that drives the wheels W. The drive device 25 includes, for example, an internal combustion engine, a rotating electric machine, a gear mechanism, and an engagement device that connects and disconnects the power transmission between rotating members, all of which are not shown. The brake system 30 is a system that generates a braking force on the wheels W. The steering system 40 is a system that moves the steered wheels among the wheels W to change the traveling direction of the vehicle 50.

The vehicle 50 is also equipped with various sensors and peripheral devices such as an accelerator sensor 51, a shift position sensor 52, a brake sensor 53, a speed sensor 54, an acceleration sensor 55, a steering angle sensor 56, a sonar 57, and a camera 58. The accelerator sensor 51 is a sensor that detects the amount of operation of the accelerator pedal by the driver. The shift position sensor 52 is a sensor that detects an instruction input that indicates the operating mode of the drive unit 25, such as a gear shift (including reverse, parking, etc.) indicated by a shift lever (not shown). The brake sensor 53 is a sensor that detects the amount of operation of the brake pedal by the driver. The speed sensor 54 is a sensor that detects the traveling speed of the vehicle 50, that is, the rotation speed of the wheels W. The acceleration sensor 55 is a sensor that detects the acceleration of the vehicle 50, and the acceleration sensor 55 of this embodiment is also capable of detecting, for example, the inclination angle and inclination direction of the ground on which the vehicle 50 is located. The steering angle sensor 56 is a sensor that detects the amount of operation of the steering wheel by the driver, and preferably detects the amount of operation as the steering angle of the vehicle 50. The sonar 57 is installed at multiple locations on the vehicle 50 and detects the presence or absence of obstacles around the vehicle 50. Preferably, the sonar 57 is an active sonar. Also, instead of the sonar 57, a laser radar or the like may be provided as an obstacle sensor. The camera 58 is installed at multiple locations on the vehicle 50 and acquires images of the surroundings of the vehicle 50. Although not shown in FIG. 3, the vehicle 50 is preferably equipped with an image processing system that performs image recognition of the presence or absence of obstacles around the vehicle 50 based on the surrounding images, and image recognition of the dividing lines that separate the parking spaces E to identify parking spaces E where no other vehicles are parked and in which the vehicle 50 can be parked.

The sensors and peripheral devices indicated by the reference numerals "51" to "58", including the above-mentioned ECU 1 (parking assistance system 100), drive system 20, brake system 30, and steering system 40, are connected to each other so as to be able to communicate with each other via an in-vehicle network 90 such as a CAN (Controller Area Network). For example, the drive system 20 controls the drive device 25 in cooperation with an accelerator sensor 51, a shift position sensor 52, a brake sensor 53, a speed sensor 54, an acceleration sensor 55, a steering angle sensor 56, etc., via the in-vehicle network 90. The brake system 30 controls the brake mechanism 35 in cooperation with the brake sensor 53 via the in-vehicle network 90. The steering system 40 controls the steering mechanism 45, including the steering wheel and steered wheels, in cooperation with the steering angle sensor 56. In this embodiment, the brake mechanism 35 and the steering mechanism 45 are driven by actuators and configured in a so-called by-wire manner via the in-vehicle network 90.

The drive system 20, brake system 30, and steering system 40 can also cooperate with sonar 57 and camera 58 (image processing system). The ECU 1 also cooperates with the drive system 20, brake system 30, steering system 40, image processing system, and sensors and peripheral devices indicated by reference numbers "51" to "58." When the ECU 1, which is the core of the parking assistance system 100, cooperates with these systems, sensors, and peripheral devices, the cooperating systems, sensors, and peripheral devices are also included in the parking assistance system 100.

Furthermore, the position information (current position Pr) of the vehicle 50 is determined by a GPS (Global Positioning System) (not shown), by identifying the relative position between the parking space E and the vehicle 50 through image recognition by an image processing system, or by communication between a transmitter (not shown) in the parking lot and a receiver (not shown) mounted on the vehicle 50. Naturally, the position information of the vehicle 50 may be determined by combining a number of these. Furthermore, it is preferable that the coordinates of the parking target position Pt in the parking space E, etc., are stored as map information in a database (storage medium) (not shown) mounted on the vehicle 50. The map information may be permanently stored in the database of the vehicle 50, or may be downloaded by communication or the like when parking assistance is received.

As described above, in this embodiment, the parking assistance system 100 performs vehicle control to move the vehicle 50 from the reverse start position (temporary stop position, initial value of the current position Pr) to the parking target position Pt. During this time, the vehicle 50 is driven automatically. Even when the vehicle control by the ECU 1 is executed and the vehicle 50 is traveling by automatic driving, the brake system 30 can apply a braking force to the wheels W when the driver operates the brakes. In this case, if the parking assistance system 100 ignores the driver's brake operation and prioritizes vehicle control, the driver's convenience may be impaired. In addition, even if the driver operates the brakes, the vehicle 50 continues to move without decelerating against the driver's intention, which may cause the driver to feel uneasy. On the other hand, if the parking assistance system 100 prioritizes the driver's brake operation, the parking assistance is interrupted or stopped, and the vehicle 50 cannot be moved appropriately to the parking space E, which may reduce the driver's convenience.

For this reason, the parking assistance system 100 of this embodiment is configured to be able to move the vehicle 50 into the parking space E while appropriately coordinating the automatic control of the driving force and braking force acting on the wheels W with the braking force caused by the driver's brake operation. The following description will also refer to the block diagram in FIG. 4, the block diagrams in FIG. 5 and FIG. 6, and the flowchart in FIG. 7.

As described above, parking assistance system 100, in which various systems, sensors, peripheral devices and ECU 1 (vehicle control unit) work together, includes a brake operation detection unit (brake sensor 53) that detects the driver's brake operation, a speed detection unit (speed sensor 54) that detects actual speed Vr that is the actual speed of vehicle 50, and an acceleration detection unit (acceleration sensor 55) that detects actual acceleration Ar that is the actual acceleration of vehicle 50. While vehicle 50 is moving to parking space E, ECU 1 executes target calculation processing to calculate a first target speed Vt1 and a first target acceleration At1 for moving and stopping vehicle 50 to parking target position Pt based on parking target position Pt set in parking space E and the current position Pr of vehicle 50. Furthermore, the ECU 1 executes a first feedback control FB1 that controls the driving force and braking force acting on the wheels W so as to bring the actual speed Vr closer to the first target speed Vt1 based on the difference between the actual speed Vr and the first target speed Vt1, and to bring the actual acceleration Ar closer to the first target acceleration At1 based on the difference between the actual acceleration Ar and the first target acceleration At1.

The driving force is mainly generated by the driving device 25 via the driving system 20, and the braking force is mainly generated by the brake mechanism 35 via the brake system 30. For example, the driving force is output from an internal combustion engine, a rotating electric machine, or a hybrid driving device that combines an internal combustion engine and a rotating electric machine, included in the driving device 25. The brake mechanism 35 includes a wheel brake provided on the wheel W, and the braking force is generated not only by the wheel brake, but also by a brake provided in the drive transmission system of the driving device 25, the negative torque of the rotating electric machine, and the engine brake of the internal combustion engine.

When the brake operation detection unit (brake sensor 53) detects the brake operation by the driver while the first feedback control FB1 is being executed, the ECU 1 executes the second feedback control FB2 instead of the first feedback control FB1. Specifically, the ECU 1 executes the second feedback control FB2, which controls the driving force and the braking force acting on the wheels W so that the lower of the first target speed Vt1 and the actual speed Vr is set as the second target speed Vt2, the lower of the first target acceleration At1 and the actual acceleration Ar is set as the second target acceleration At2, and the actual speed Vr approaches the second target speed Vt2 based on the difference between the actual speed Vr and the second target speed Vt2, and the actual acceleration Ar approaches the second target acceleration At2 based on the difference between the actual acceleration Ar and the second target acceleration At2. Note that the acceleration caused by the brake operation is a negative value because it is an acceleration that decelerates the vehicle 50. Therefore, the "acceleration" compared here is not an absolute value comparison, but a value taking into account positive and negative.

As shown in FIG. 4, the parking assistance system 100 includes a position feedback controller 11 (position FB), a speed feedback controller 12 (speed FB), and an acceleration feedback controller 13 (acceleration FB) as feedback controllers. The position feedback controller 11 calculates a target speed Vt according to a moving distance from the current position Pr to the parking target position Pt through a moving path K, for example, based on the parking target position Pt and the current position Pr of the vehicle 50. The speed feedback controller 12 calculates a target acceleration At for moving at the target speed Vt based on the target speed Vt and the actual speed Vr. The acceleration feedback controller 13 calculates a power F for accelerating or decelerating the vehicle 50 at the target acceleration At based on the target acceleration At and the actual acceleration Ar. The power F is a driving force and a braking force acting on the wheels W. In general, when accelerating the vehicle 50, the power F is a driving force, and when decelerating the vehicle 50, the power F is a braking force.

FIGS. 5 and 6 show block diagrams of the feedback controller. In this embodiment, the position feedback controller 11, the velocity feedback controller 12, and the acceleration feedback controller 13 are all configured as PI controllers that perform proportional-integral control. As shown in FIG. 5 and FIG. 6, the feedback controller includes a proportional gain 15 (Kp), an integral controller 16 (1/s), and an integral gain 17 (Ki). Of course, one or more of these controllers may be configured as a PID controller that performs proportional-integral-derivative control.

The block diagram in FIG. 5 illustrates an example of a controller that executes common control regardless of whether or not the driver operates the brakes. In this embodiment, it corresponds to the position feedback controller 11. The position feedback controller 11 executes proportional control and integral control on the difference between the parking target position Pt and the current position Pr to calculate the target speed Vt. As described above, the speed feedback controller 12 that uses the target speed Vt executes different controls, specifically the first feedback control FB1 or the second feedback control FB2, depending on whether or not the driver operates the brakes. The target speed Vt calculated by the position feedback controller 11 corresponds to the first target speed Vt1, which is the target speed Vt in the first feedback control FB1.

The block diagram in FIG. 6 illustrates an example of a controller that executes different controls depending on whether or not the driver operates the brakes. In this embodiment, it corresponds to the speed feedback controller 12 and the acceleration feedback controller 13. The speed feedback controller 12 executes proportional control and integral control on the difference between the target speed Vt and the actual speed Vr to calculate the target acceleration At. As described above, the acceleration feedback controller 13 that uses the target acceleration At executes different controls, specifically the first feedback control FB1 or the second feedback control FB2, depending on whether or not the driver operates the brakes. The target acceleration At calculated by the speed feedback controller 12 corresponds to the first target acceleration At1, which is the target acceleration At in the first feedback control FB1. The acceleration feedback controller 13 also executes proportional control and integral control on the difference between the target acceleration At and the actual acceleration Ar to calculate the power F.

The speed feedback controller 12 and the acceleration feedback controller 13 execute different controls, specifically the first feedback control FB1 or the second feedback control FB2, depending on whether or not the driver operates the brakes. For this reason, in contrast to the feedback controller illustrated in FIG. 5, the feedback controller illustrated in FIG. 6 includes a selector 18 that selects the target value before the difference calculator between the target value (target speed Vt, target acceleration At) and the actual value (actual speed Vr, actual acceleration Ar) that is fed back.

In the speed feedback controller 12, the selector 18 selects either the first target speed Vt1 or the actual speed Vr as the second target speed Vt2. Specifically, when the brake sensor 53 detects a brake operation by the driver, the selector 18 selects the lower of the target speed Vt (first target speed Vt1) and the actual speed Vr as the target speed Vt (second target speed Vt2). When the brake sensor 53 does not detect a brake operation by the driver, the selector 18 selects the first target speed Vt1 as the target speed Vt, regardless of the magnitude relationship between the target speed Vt (first target speed Vt1) and the actual speed Vr. When the target speed Vt is set to the first target speed Vt1, the speed feedback controller 12 executes the first feedback control FB1 based on the first target speed Vt1 and the actual speed Vr. When the target speed Vt is set to the second target speed Vt2, that is, when the target speed Vt is selectively set from the first target speed Vt1 and the actual speed Vr, the speed feedback controller 12 executes the second feedback control FB2 based on the second target speed Vt2 and the actual speed Vr.

In the acceleration feedback controller 13, the selector 18 selects either the first target acceleration At1 or the actual acceleration Ar as the second target acceleration At2. Specifically, when the brake sensor 53 detects a brake operation by the driver, the selector 18 selects the lower of the target acceleration At (first target acceleration At1) and the actual acceleration Ar as the target acceleration At (second target acceleration At2). When the brake sensor 53 does not detect a brake operation by the driver, the selector 18 selects the first target acceleration At1 as the target acceleration At, regardless of the magnitude relationship between the target acceleration At (first target acceleration At1) and the actual acceleration Ar. When the target acceleration At is set to the first target acceleration At1, the acceleration feedback controller 13 executes the first feedback control FB1 based on the first target acceleration At1 and the actual acceleration Ar. When the target acceleration At is set to the second target acceleration At2, that is, when the target acceleration At is selectively set from the first target acceleration At1 and the actual acceleration Ar, the acceleration feedback controller 13 executes the second feedback control FB2 based on the second target acceleration At2 and the actual acceleration Ar.

In the second feedback control FB2, when actual values (actual speed Vr, actual acceleration Ar) are selected as the target values (target speed Vt, target acceleration At), the difference between the target value and the actual value is zero. Therefore, regardless of the proportional gain 15 (Kp), the output from the proportional control is zero. Also, in the integral control, the accumulated value is zero regardless of the integral gain 17 (Ki), so the speed change and acceleration change due to the driver's brake operation are prevented from being accumulated and becoming a disturbance.

In this embodiment, the first feedback control FB1 and the second feedback control FB2 have the same control block configuration, but only the target values are different. However, this does not prevent the control block configurations of the first feedback control FB1 and the second feedback control FB2 from being different.

The procedure for selecting the first feedback control FB1 and the second feedback control FB2 will be described below with reference to the flowchart in FIG. 7. First, it is determined whether or not the termination condition of the vehicle control for moving the vehicle 50 to the parking space E is met (#1). For example, if the vehicle 50 has completed moving to the parking space E, it is determined that the termination condition is met. In addition, it is also determined that the termination condition is met if an obstacle is detected, it is determined that the vehicle 50 cannot move along the movement path K to the parking target position Pt, and the vehicle 50 stops moving and stops. If it is determined that the termination condition is met, the ECU 1 ends the vehicle control.

If it is determined in step #1 that the termination condition is not satisfied, then it is determined whether or not the driver has operated the brakes (#2). In this embodiment, whether or not the brakes have been operated is determined based on the detection result of the brake sensor 53 serving as a brake operation detection unit. As described above, the brake mechanism 35 is driven and controlled by the by-wire via the brake system 30. Therefore, the physical quantity for determining whether or not the brakes have been operated is not limited to the amount of operation of the brake pedal by the driver, but may be a braking command value given to the brake mechanism 35 by the brake system 30 based on the amount of operation. In this case, the brake system 30 also corresponds to the brake operation detection unit. It is preferable that the ECU 1 determines whether or not the brakes have been operated based on these physical quantities and a preset reference value. It is also possible to determine whether or not the brakes have been operated, without relying on such physical quantities, simply based on whether or not the driver has operated the brake pedal.

In step #2, if the brake sensor 53 does not detect a brake operation by the driver, it is determined that no brake operation is being performed, the first target speed Vt1 is maintained as the target speed Vt, and the first target acceleration At1 is maintained as the target acceleration At (#20), and the first feedback control FB1 is executed.

If the brake sensor 53 detects a brake operation by the driver, it is determined in step #2 that the driver has applied the brakes, and then the magnitudes of the target speed Vt and the actual speed Vr are compared (#3). This target speed Vt is the first target speed Vt1 in the first feedback control FB1, so in step #3, the magnitudes of the first target speed Vt1 and the actual speed Vr are compared. If it is determined in step #3 that the actual speed Vr is less than the first target speed Vt1, the actual speed Vr is set as the target speed Vt (#4). When the actual speed Vr is set, the target speed Vt is the second target speed Vt2. Therefore, in step #4, the actual speed Vr is set as the second target speed Vt2.

If it is determined in step #3 that the target speed Vt (first target speed Vt1) is equal to or lower than the actual speed Vr, the current target speed Vt is maintained. This is equivalent to setting the target speed Vt (first target speed Vt1) as the target speed Vt (#4B). Since the value is maintained, step #4B does not need to be executed as shown by the dashed line in FIG. 7, but in step #4B, the first target speed Vt1 is set as the second target speed Vt2. The second target speed Vt2 is set through steps #3, #4, and #4B, and the speed feedback controller 12 executes the second feedback control FB2.

Once the second target speed Vt2 is set, the magnitudes of the target acceleration At and the actual acceleration Ar are then compared (#5). This target acceleration At is the first target acceleration At1 in the first feedback control FB1, so in step #5, the magnitudes of the first target acceleration At1 and the actual acceleration Ar are compared. If it is determined in step #5 that the actual acceleration Ar is less than the first target acceleration At1, the actual acceleration Ar is set as the target acceleration At (#6). The target acceleration At when the actual acceleration Ar is set is the second target acceleration At2. Therefore, in step #6, the actual acceleration Ar is set as the second target acceleration At2.

If it is determined in step #5 that the target acceleration At (first target acceleration At1) is equal to or less than the actual acceleration Ar, the current target acceleration At is maintained. This is equivalent to setting the target acceleration At (first target acceleration At1) as the target acceleration At (#6B). Since the value is maintained, step #6B does not need to be executed as shown by the dashed line in FIG. 7, but in step #6B, the first target acceleration At1 is set as the second target acceleration At2. The second target acceleration At2 is set through steps #5, #6, and #6B, and the acceleration feedback controller 13 executes the second feedback control FB2.

After the second target speed Vt2 and the second target acceleration At2 are set and the second feedback control FB2 is executed, the target speed Vt and the target acceleration At are reset to the first target speed Vt1 and the first target acceleration At1, respectively (#20), and the above-mentioned series of processes from step #1 are preferably repeated.

If it is determined in step #2 after the second feedback control FB2 is executed instead of the first feedback control FB1 that there is no brake operation, the process proceeds to step #20, where the first feedback control FB1 is resumed instead of the second feedback control FB2. That is, if the brake sensor 53 no longer detects a brake operation while the second feedback control FB2 is being executed, the ECU 1 executes the first feedback control FB1 instead of the second feedback control FB2.

In this way, according to this embodiment, when the driver no longer operates the brakes, it is possible to return to the first feedback control FB1, which is the normal feedback control. Therefore, even if the driver intermittently operates the brakes while the vehicle 50 is running under vehicle control by the vehicle control unit (ECU1), the first feedback control FB1 and the second feedback control FB2 can be appropriately executed, and parking assistance by the vehicle control unit (ECU1) can be appropriately continued.

Note that, in the above, with reference to Figures 6, 7, etc., an example has been described in which, when the brake system 30 detects a brake operation by the driver while the ECU 1 is executing the first feedback control FB1, the ECU 1 executes the second feedback control FB2 in place of the first feedback control FB1, which controls the power F (driving force and braking force) acting on the wheels W so that the lower of the first target speed Vt1 and the actual speed Vr is set as the second target speed Vt2, the lower of the first target acceleration At1 and the actual acceleration Ar is set as the second target acceleration At2, and the actual speed Vr approaches the second target speed Vt2 based on the difference between the actual speed Vr and the second target speed Vt2, and the actual acceleration Ar approaches the second target acceleration At2 based on the difference between the actual acceleration Ar and the second target acceleration At2.

However, in the second feedback control FB2, the acceleration may not be included in the control target, and only the speed may be the control target. That is, when the brake system 30 detects the brake operation by the driver while the ECU 1 is executing the first feedback control FB1, the ECU 1 may execute the second feedback control FB2, instead of the first feedback control FB1, in which the lower of the first target speed Vt1 and the actual speed Vr is set as the second target speed Vt2, and the power F (driving force and braking force) acting on the wheels W is controlled so as to bring the actual speed Vr closer to the second target speed Vt2 based on the difference between the actual speed Vr and the second target speed Vt2. In FIG. 6, the control targeting the speed is executed, and in FIG. 7, steps #5, #6, and #6B may be omitted, and detailed explanation will be omitted since it can be easily understood by those skilled in the art.

As described above, the vehicle 50 is equipped with sonars 57 that are installed at multiple locations on the vehicle 50 and detect the presence or absence of obstacles around the vehicle 50. These sonars 57 correspond to the obstacle detection unit in the parking assistance system 100 that detects obstacles that may come into contact with the vehicle 50. In addition, if a laser radar or the like is provided, the laser radar also corresponds to the obstacle detection unit. As described above, the vehicle 50 may also be equipped with an image processing system that is installed at multiple locations on the vehicle 50 and performs image recognition to determine the presence or absence of obstacles around the vehicle 50 based on images captured by a camera 58 that captures images of the vehicle 50. Such an image processing system can also cooperate with the parking assistance system 100, in which case the image processing system corresponds to the obstacle detection unit in the parking assistance system 100.

In this way, the parking assistance system 100 can further include an obstacle detection unit that detects an obstacle that may come into contact with the vehicle 50. Then, when the obstacle detection unit detects an obstacle while the vehicle 50 is moving to the parking space E, the ECU 1 preferably calculates the first target speed Vt1 and the first target acceleration At1 in the target calculation process so that the vehicle 50 stops without coming into contact with the obstacle.

As a result, even if there is an obstacle that may come into contact with the vehicle 50, the first feedback control FB1 and the second feedback control can be selectively executed appropriately, and parking assistance can be performed to prevent the vehicle 50 from coming into contact with the obstacle.

As described above, the parking assistance system 100 of this embodiment can move the vehicle 50 into the parking space E while appropriately balancing the automatic control of the driving force and braking force acting on the wheels W and the braking force caused by the driver's brake operation.

(Summary of the embodiment)
The parking assistance system (100) described above will be briefly summarized below.

In one embodiment, the parking assistance system (100) is a parking assistance system (100) equipped with a vehicle control unit (1) that controls the driving force and braking force acting on the wheels (W) to control the vehicle (50) equipped with the wheels (W) to move the vehicle (50) to a parking space (E), and includes a brake operation detection unit (30) that detects the driver's brake operation, a speed detection unit (54) that detects the actual speed (Vr) of the vehicle (50), and an actual acceleration detection unit (55) that detects the actual acceleration of the vehicle (50). and an acceleration detection unit (55) for detecting an actual acceleration (Ar) which is equal to or greater than the actual acceleration (Ar) of the vehicle (50). During the movement of the vehicle (50) to the parking space (E), the vehicle control unit (1) executes a target calculation process for calculating a first target speed (Vt1) and a first target acceleration (At1) for moving the vehicle (50) to the parking target position (Pt) and stopping the vehicle (50) based on a parking target position (Pt) set in the parking space (E) and a current position (Pr) of the vehicle (50), and a first feedback control (FB1) for controlling a driving force and a braking force acting on the wheels (W) so as to bring the actual speed (Vr) closer to the first target speed (Vt1) based on a difference between the actual speed (Vr) and the first target speed (Vt1), and so as to bring the actual acceleration (Ar) closer to the first target acceleration (At1) based on a difference between the actual acceleration (Ar) and the first target acceleration (At1); and during the execution of the first feedback control (FB1), the brake operation detection unit (30) When the brake operation by the driver is detected, instead of the first feedback control (FB1), a second feedback control (FB2) is executed in which the lower of the first target speed (Vt1) and the actual speed (Vr) is set as a second target speed (Vt2), and the driving force (F) and braking force (F) acting on the wheels (W) are controlled so that the actual speed (Vr) approaches the second target speed (Vt2) based on the difference between the actual speed (Vr) and the second target speed (Vt2).

According to this configuration, when the actual speed (Vr) of the vehicle (50) becomes lower than the target value of the feedback control due to the brake operation of the driver while the vehicle (50) is traveling under the vehicle control of the vehicle control unit (1), the vehicle control unit (1) changes the target value to a lower value in accordance with the actual speed (Vr). In other words, the vehicle control unit (1) executes the second feedback control (FB2) instead of the first feedback control (FB1). If the first feedback control (FB1) is continued even if the actual speed (Vr) becomes lower than the target value due to the brake operation of the driver, the change in speed due to the brake operation of the driver may be treated as a disturbance, and the traveling speed may be maintained. However, according to this configuration, the feedback control can be appropriately continued by avoiding the output of a driving force in the accelerating direction by recognizing the brake operation of the driver as a disturbance, and the vehicle (50) can be prevented from traveling without decelerating against the driver's intention. On the other hand, even if the driver brakes, if the actual speed of the vehicle (50) is higher than the target value of the (Vr) feedback control, the vehicle control unit (1) maintains the target value. That is, the vehicle control unit (1) continues to execute the first feedback control (FB1). Therefore, even if the driver brakes while the vehicle (50) is traveling under the vehicle control of the vehicle control unit (1), the vehicle (50) can be appropriately stopped at the parking target position (Pt). In addition, in this case, the vehicle is decelerated to a degree equivalent to or greater than the driver's brake operation, so that deceleration according to the driver's intention is also realized. In this way, according to this configuration, a parking assistance system (100) can be realized that can move the vehicle (50) to the parking space (E) while appropriately adjusting the automatic control of the driving force (F) and braking force (F) acting on the wheels (W) and the braking force due to the driver's brake operation.

Here, it is preferable that the second feedback control (FB2) includes a process of controlling the driving force (F) and the braking force (F) acting on the wheels (W) so as to bring the actual acceleration (Ar) closer to the second target acceleration (At2), based on the difference between the actual acceleration (Ar) and the second target acceleration (At2), by setting the lower of the first target acceleration (At1) and the actual acceleration (Ar) as the second target acceleration (At2).

According to this configuration, when the actual speed (Vr) and actual acceleration (Ar) of the vehicle (50) become lower than the target values of the feedback control due to the driver's brake operation while the vehicle is traveling under the vehicle control of the vehicle control unit (1), the vehicle control unit (1) changes the target values to lower values in accordance with the actual speed (Vr) and actual acceleration (Ar). In other words, the vehicle control unit (1) executes the second feedback control (FB2) instead of the first feedback control (FB1). If the first feedback control (FB1) is continued even if the actual speed (Vr) and actual acceleration (Ar) become lower than the target values due to the driver's brake operation, the change in speed and acceleration due to the driver's brake operation may be treated as a disturbance, and the traveling speed and acceleration may be maintained. However, according to this configuration, the driver's brake operation is recognized as a disturbance, and a driving force in the accelerating direction is not output, so that the feedback control can be appropriately continued, and the vehicle can be prevented from traveling without decelerating against the driver's intention. On the other hand, even if the driver applies the brakes, if the actual speed (Vr) and actual acceleration (Ar) of the vehicle (50) are higher than the target values of the feedback control, the vehicle control unit (1) maintains the target values. In other words, the vehicle control unit (1) continues to execute the first feedback control (FB1). Therefore, even if the driver applies the brakes while the vehicle (50) is traveling under vehicle control by the vehicle control unit (1), the vehicle (50) can be appropriately stopped at the parking target position (Pt). In this case, too, the vehicle is decelerated by more than the driver's brake operation, so deceleration in line with the driver's intention is also achieved.

Furthermore, the parking assistance system (100) is preferably configured such that, when the brake operation detection unit (30) no longer detects the brake operation while the vehicle control unit (1) is executing the second feedback control (FB2), the parking assistance system (100) executes the first feedback control (FB1) instead of the second feedback control (FB2).

In this way, according to this embodiment, when the driver no longer operates the brakes, it is possible to return to the first feedback control (FB1), which is normal feedback control. Therefore, even if the driver intermittently operates the brakes while the vehicle (50) is traveling under vehicle control by the vehicle control unit (1), the first feedback control (FB1) and the second feedback control (FB2) can be appropriately executed, and parking assistance by the vehicle control unit (1) can be appropriately continued.

1: ECU (vehicle control unit), 30: Brake system (brake operation detection unit), 50: vehicle, 53: Brake sensor (brake operation detection unit), 54: Speed sensor (speed detection unit), 55: Acceleration sensor (acceleration detection unit), 100: Parking assistance system, Ar: Actual acceleration, At: Target acceleration, At1: First target acceleration, At2: Second target acceleration, E: Parking space, F: Power (driving force, braking force), FB: Acceleration, FB: Speed, FB1: First feedback control, FB2: Second feedback control, Pr: Current position, Pt: Parking target position, Vr: Actual speed, Vt: Target speed, Vt1: First target speed, Vt2: Second target speed, W: Wheels

Claims (3)

A parking assistance system including a vehicle control unit that controls a driving force and a braking force acting on a wheel to perform vehicle control for moving a vehicle having the wheel into a parking space,
A brake operation detection unit that detects a brake operation by a driver;
a speed detection unit for detecting an actual speed of the vehicle;
An acceleration detection unit that detects an actual acceleration of the vehicle,
The vehicle control unit, while the vehicle is moving to the parking space,
A target calculation process is executed to calculate a first target speed and a first target acceleration for moving the vehicle to the parking target position and stopping the vehicle based on a parking target position set for the parking space and a current position of the vehicle, and
execute a first feedback control for controlling a driving force and a braking force acting on the wheels so as to bring the actual speed closer to the first target speed based on a difference between the actual speed and the first target speed, and to bring the actual acceleration closer to the first target acceleration based on a difference between the actual acceleration and the first target acceleration;
a brake operation detection unit that detects the brake operation by the driver while the first feedback control is being executed, and then, instead of the first feedback control, a second feedback control is executed in which the lower of the first target speed and the actual speed is set as a second target speed, and the driving force and braking force acting on the wheels are controlled so as to bring the actual speed closer to the second target speed based on a difference between the actual speed and the second target speed. The parking assistance system of claim 1, wherein the second feedback control includes a process of controlling the driving force and braking force acting on the wheels so as to bring the actual acceleration closer to the second target acceleration based on the difference between the first target acceleration and the actual acceleration, the lower of which is set as a second target acceleration. 3. The parking assistance system according to claim 1, wherein the vehicle control unit executes the first feedback control instead of the second feedback control when the brake operation detection unit no longer detects the brake operation while the second feedback control is being executed.

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