Travel control device

Abstract

To provide a travel control device which can converge lateral deviation and a direction of a vehicle with respect to a target position.SOLUTION: A travel control device moving a vehicle to a target position through automatic operation control at a time of parking / stopping or shifting aside comprises: a position detection unit which detects central position information of a front wheel shaft of a vehicle or a rear wheel shaft thereof; a yaw-angle detection unit which detects a yaw-angle of the vehicle; a speed detection unit which detects speed of the vehicle based on wheel speed of the front wheels or the rear wheels; a target steering angle calculation unit which calculates target steering angles of the front wheels and the rear wheels; and a travel control unit which steers the front wheels and the rear wheels according to the calculated target steering angles. The target steering angle calculation unit calculates the target steering angle of the front wheels based on an expression (1) and calculates the target steering angle of the rear wheels based on an expression (2).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a technology for executing automatic driving control that allows a vehicle to drive autonomously. [Background technology]

[0002] Patent Document 1 discloses an automatic parking device that detects the vehicle's surrounding environment, calculates a parking position and parking path, and automatically moves the vehicle along the parking path to the parking position. This automatic parking device detects the amount of deviation from the parking path at the current location, fixes the front wheel steering according to the deviation, and performs corrective steering by steering the rear wheels. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 10-264839 Summary of the Invention [Problem to be solved by the invention]

[0004] In the technology described in Patent Document 1, when corrective steering is performed, the direction of the vehicle changes, so there is a risk that the direction of the vehicle at the parking position will tilt with respect to the traveling direction of the parking path.

[0005] An object of the present invention is to provide a technology that can converge the lateral deviation and the orientation of the vehicle relative to the target position. [Means for solving the problem]

[0006] In order to solve the above problems, one aspect of the present invention is a cruise control device that moves a vehicle to a target position by automatic driving control when parking, stopping, or pulling over, and includes a position detection unit that detects center position information of the vehicle's front axle or rear axle, a yaw angle detection unit that detects the yaw angle of the vehicle, a speed detection unit that detects the vehicle speed based on the wheel speed of the front or rear wheels, a target steering angle calculation unit that calculates target steering angles for the front wheels and rear wheels, and a cruise control unit that steers the front wheels and rear wheels in accordance with the calculated target steering angles. The target steering angle calculation unit calculates the target steering angle of the front wheels using equation (1), and calculates the target steering angle of the rear wheels using equation (2). [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a technique that can converge the lateral deviation and the direction of the vehicle relative to the target position. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram illustrating a functional configuration of a cruise control system according to an embodiment. [Figure 2] FIG. 10 is a diagram for explaining standby processing during automatic driving control. DETAILED DESCRIPTION OF THE INVENTION

[0009] FIG. 1 is a diagram illustrating the operation of a cruise control device according to an embodiment. FIG. 1 shows a vehicle 10 traveling along a travel route 18 toward a target position 16. The cruise control device mounted on the vehicle 10 performs automatic driving control to autonomously drive the vehicle 10 at low speeds when parking or pulling over to the side of a road. The target position 16 may be, for example, a parking position or a stopping position, or may be an intermediate point on the way to the parking position. The intermediate point may be a point where the vehicle 10 changes direction to move forward or backward when parking.

[0010] The front wheels 12 and rear wheels 14 of the vehicle 10 are each steerable. f is the coordinate (x f ,y f) The coordinates of the target position 16 are expressed as (0,0), so the center position C f coordinates (x f ,y f ) indicates the position of the vehicle 10 relative to the target position 16. y f is the amount of lateral deviation relative to the target position 16. The yaw angle θ of the vehicle is expressed based on the orientation of the target vehicle 10 at the target position 16. The orientation of the target vehicle 10 at the target position 16 is the target yaw angle, and the target yaw angle is zero.

[0011] Vehicle 10 speed V is calculated based on the rotation speed of the front axle. f The center position of the rear wheel axle C r The coordinates at (x r ,y r ) and the speed V of the vehicle 10 is calculated based on the rotation speed of the rear axle. r may be calculated.

[0012] The cruise control device calculates the target steering angle δ of the front wheels 12 to move towards the target position 16 using a calculation formula to be described later. f and the target steering angle δ of the rear wheels 14 r In particular, the cruise control device calculates the abscissa y f The target steering angle is calculated so that the yaw angle θ becomes zero. When an attempt is made to correct the lateral deviation of the vehicle 10, the yaw angle θ will be shifted. However, by using the calculation formula described later, the horizontal coordinate y f and the yaw angle θ can be converged to zero.

[0013] 2 is a diagram showing the functional configuration of the driving control device 20. The driving control device 20 controls the driving device 22 when parking or pulling over to the side of a road, thereby moving the vehicle 10 to a target position by automatic driving control. The driving device 22 has a steering means that applies a driving force to the wheels to steer the wheels, a driving means that rotates the wheels to move the vehicle forward, and a braking means that applies a braking force to the wheels.

[0014] The cruise control device 20 includes an object detection unit 24, a yaw angle detection unit 26, a position detection unit 28, a speed detection unit 30, a target position calculation unit 32, a target steering angle calculation unit 34, a target speed calculation unit 36, and a cruise control unit 38.

[0015] The object detection unit 24 includes an on-board camera, millimeter wave radar, optical radar, and an acoustic wave sensor, and detects objects located around the vehicle. The yaw angle detection unit 26 detects the angle of the vehicle 10 in the longitudinal direction relative to a target yaw angle as the yaw angle of the vehicle 10.

[0016] The position detection unit 28 may detect the position information of the vehicle using a Global Navigation Satellite System (GNSS), and may detect position information indicating the distance and direction to the target position 16 based on the captured image. The position information of the vehicle may include the center position C of the front wheel axle. f The information may indicate the center position C of the rear wheel shaft. r The information may indicate the center position C of the front wheel shaft. f and the center position of the rear wheel axle C r can be converted based on the wheelbase L.

[0017] The speed detection unit 30 detects the speed V of the vehicle 10 based on the wheel speed of the front wheels 12. f The speed detection unit 30 detects the speed V of the vehicle 10 based on the wheel speed of the rear wheels 14. r The speed V corresponding to the rear wheels may be detected. r is V f cos(δ f )=V r cos(δ r ) based on the formula, the speed V according to the front wheels f can be calculated from and vice versa.

[0018] The target position calculation unit 32 calculates the target position 16 based on the detection result of the object detection unit 24. The target position 16 determines not only the position but also the orientation of the vehicle 10. Note that the determination of the target position 16 may require instructions from the driver.

[0019] The target speed calculation unit 36 ​​calculates the target speed of the vehicle 10 based on the detection result of the speed detection unit 30. The target speed may include a target deceleration. The target speed of the vehicle 10 may be set to a predetermined vehicle speed or less, for example, a few kilometers per hour or less. The travel control unit 38 controls the speed of the vehicle 10 to be the predetermined vehicle speed or less, and causes the vehicle 10 to travel at a low speed.

[0020] The target steering angle calculation unit 34 calculates the target steering angle δ of the front wheels 12 using the following equation (1): f is calculated, and the target steering angle δ of the rear wheels 14 is calculated using the following equation (2): r The travel control unit 38 calculates the calculated target steering angle δ f ,δ r The travel device 22 is controlled in response to the steering wheel 12 and the rear wheels 14.

number

number

[0021] Equations (1) and (2) are used to calculate the velocity V of the vehicle 10. f The calculation is based on the assumption that the vehicle is moving at a low speed, i.e., that the slip angle of the wheels is very small. The center position yf and yaw angle θ of the vehicle 10 converge to the target position 16 in a first-order lag system according to the formulas (1) and (2). The first time constant T y and the second time constant T θ The speed of convergence can be set by optimally setting the target steering angle. The target steering angle calculation unit 34 calculates the target steering angle when the vehicle 10 moves forward or backward.

[0022] The target steering angle calculation unit 34 can change the orientation of the vehicle 10 at the target position 16 by rotating in the yaw direction around the target position 16 as an axis. Rotation in the yaw direction around the target position 16 as an axis can be achieved by adding or subtracting the angle of that rotation to the yaw angle θ of the vehicle 10. This is used, for example, when the vehicle 10 is to turn multiple times.

[0023] The target steering angle calculation unit 34 calculates the speed V of the vehicle 10 detected based on not only the wheel speed of the front wheels 12 but also the wheel speed of the rear wheels 14. r The target steering angle δ of the front wheels 12 and the rear wheels 14 is calculated using f ,δ r In other words, control is possible not only by the sensor provided on the front wheel 12 but also by the sensor provided on the rear wheel 14.

[0024] The target steering angle calculation unit 34 calculates the first time constant T y and the second time constant T θ At least one of the above is determined based on the speed V of the vehicle 10. f The time constant is set according to the speed V of the vehicle 10. r For example, when the vehicle speed is high, the time constant may be set to slow down the convergence in order to reduce the lateral G force.

[0025] The target steering angle calculation unit 34 calculates (y f / T y V) -1 < (y f / T y For example, the target steering angle calculation unit 34 calculates the target steering angle (y f / T y If V) is less than -1, it is calculated as -0.99, and (y f / T y If V) is 1 or more, it is calculated as 0.99.

[0026] The target steering angle calculation unit 34 calculates the center position y of the front wheel shaft shown in equations (1) and (2). f (y f -y t ) and correct the target position 16 to yt Only y can be changed. t is an arbitrarily set constant.

[0027] The target steering angle calculation unit 34 calculates the yaw angle θ based on the center position of the front wheel 12 shaft shown in equations (1) and (2) as (θ - θ t ) and correct the orientation of the vehicle 10 at the target position to θ t Only θ can be changed. t is an arbitrarily set constant.

[0028] The target steering angle calculation unit 34 calculates V f cos(δ f )=V r cos(δ r ) based on the equation (1) and the equation (2), the speed V of the vehicle 10 based on the wheel speed of the front wheel 12 f The speed V of the vehicle 10 based on the wheel speed of the rear wheel 14 r For example, the speed V corresponding to the front wheels 12 can be calculated from f The speed V corresponds to the rear wheel 14 r If the accuracy is better than that of r When controlling the front wheel 12, the speed V f This allows the number of sensors used to estimate the speed to be increased, which is expected to reduce noise.

[0029] V included in formula (1) and formula (2) f Set to 1, and V from equations (1) and (2) f may be deleted. In other words, the target steering angle is calculated ignoring the vehicle speed. This makes it possible to prevent the target steering angle from becoming too large when the vehicle is traveling at an extremely low speed. This may be performed when the vehicle is traveling at or below a predetermined extremely low speed.

[0030] The present disclosure has been described above based on examples. The present disclosure is not limited to the above examples, and various modifications such as design changes may be made based on the knowledge of those skilled in the art. [Explanation of symbols]

[0031] 10 vehicle, 12 front wheel, 14 rear wheel, 16 target position, 18 driving path, 20 driving control device, 22 driving device, 24 object detection unit, 26 yaw angle detection unit, 28 position detection unit, 30 speed detection unit, 32 target position calculation unit, 34 target steering angle calculation unit, 36 target speed calculation unit, 38 driving control unit.

Claims

[Claim 1] A driving control device that moves a vehicle to a target position by automatic driving control when parking or stopping or pulling over, a position detection unit that detects center position information of a front wheel shaft or a rear wheel shaft of the vehicle; a yaw angle detection unit that detects a yaw angle of the vehicle; a speed detection unit that detects the speed of the vehicle based on the wheel speed of the front wheels or the rear wheels; a target steering angle calculation unit that calculates target steering angles of the front wheels and the rear wheels; a travel control unit that steers the front wheels and the rear wheels in accordance with the calculated target steering angle, the target steering angle calculation unit calculates a target steering angle of the front wheels by the following equation (1), and calculates a target steering angle of the rear wheels by the following equation (2), the target steering angle calculation unit is capable of rotating in a yaw direction around the target position as an axis to change the orientation of the vehicle at the target position, the target steering angle calculation unit is capable of calculating the target steering angle using the speed of the vehicle detected based on the rotation speed of the rear wheel shaft, The travel control unit controls the speed of the vehicle to be equal to or less than a predetermined vehicle speed, The target steering angle calculation unit calculates a first time constant T ｙ and the second time constant T θ at least one of the above is set in accordance with the speed of the vehicle; The target steering angle calculation unit calculates (y ｆ / T ｙ V) to -1 < (y ｆ / T ｙ V) < 1, the target steering angle calculation unit is capable of changing the target position by correcting the center position information of the front wheel shaft or the rear wheel shaft shown in the following formula (1) and formula (2), the target steering angle calculation unit is capable of changing the orientation of the vehicle at the target position by correcting the yaw angle shown in the following equations (1) and (2), The target steering angle calculation unit is V ｆ cos(δ ｆ ) = V ｒ cos(δ ｒ ) the speed of the vehicle based on the front wheels included in the following equations (1) and (2) can be calculated from the speed of the vehicle based on the wheel speed of the rear wheels, The cruise control device is characterized in that the target steering angle calculation unit calculates a target steering angle when the vehicle moves forward or backward. [Equation 1] [Equation 2] δ ｆ is the target steering angle of the front wheels, and δ ｒ is the target steering angle of the rear wheels, and y ｆ is the center position of the front wheel axle relative to the target position, and V ｆ is the vehicle speed based on the front wheel speed, and T ｙ is the first time constant, and T θ is the second time constant, and θ is the yaw angle of the vehicle.

Images