Parking Route Generation Device

Abstract

To highly accurately generate a parking route of a connection vehicle at low calculation cost.SOLUTION: A parking route generating device 16 includes: a pattern storing part 21 for storing a plurality of retreat route patterns based on a rear shaft of a trailer 4 for each wheel base length of the trailer 4; a position setting part 22 for setting a parking start position A1 of the connection vehicle 2 and a parking target position A2 of the connection vehicle 2; a locus generating part 23 for generating a plurality of retreat locus profiles on the basis of information indicating a wheel base length of the trailer 4 in the connection vehicle 2 and information stored in the pattern storage part 21; a locus selecting part 24 for selecting the retreat locus profile in which the connection wheel 2 does not collide with an obstacle 50; a route determining part 25 for determining a parking route so that the connection vehicle 2 starting parking from the parking start position A1 retreats after advancement and thereby is parked at the parking target position A2; and a route outputting part 26 for outputting the parking route.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] One aspect of the present invention relates to a parking route generation device.

Background Art

[0002] For example, Patent Document 1 describes a reverse parking support device that supports the reverse parking of a coupled vehicle including a tractor and a trailer. The reverse parking support device described in Patent Document 1 creates a parking target route from the position of the own vehicle to the parking target position, and sets the steering angle of the coupled vehicle so that the coupled vehicle moves along the parking target route. At this time, for the parking target route, a traveling trajectory of the coupled vehicle when performing follow-up control using the Pure Pursuit method is created.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, in the parking route of the coupled vehicle, particularly during reverse travel, the movement becomes complicated. For this reason, in generating the parking route of the coupled vehicle, it is difficult to generate the reverse route with high accuracy, and also, a problem arises in that the calculation cost increases when trying to generate it with high accuracy as much as possible.

[0005] One aspect of the present invention has been made in view of the above circumstances, and an object thereof is to generate a parking route of a coupled vehicle with high accuracy and low calculation cost.

Means for Solving the Problems

[0006] A parking path generation device according to an aspect of the present invention is a parking path generation device that generates a parking path for parking a coupled vehicle including a tractor and a trailer, and for each wheelbase type of the trailer, a plurality of reverse path patterns based on the rear axle of the trailer, and a pattern storage unit that stores a plurality of reverse path patterns with different degrees of change in curvature in the path; a position setting unit that sets a parking start position of the coupled vehicle and a parking target position of the coupled vehicle based on information including the current position of the coupled vehicle; a trajectory generation unit that identifies a plurality of reverse path patterns corresponding to the wheelbase type of the trailer in the coupled vehicle based on information indicating the wheelbase type of the trailer in the coupled vehicle and the information stored in the pattern storage unit, and generates a plurality of reverse trajectory profiles based on the identified plurality of reverse path patterns; a trajectory selection unit that selects a reverse trajectory profile in which the coupled vehicle does not collide with an obstacle based on the parking target position, information on obstacles around the coupled vehicle, and the plurality of reverse trajectory profiles; a path determination unit that determines a parking path such that the coupled vehicle that starts parking from the parking start position is parked at the parking target position by moving forward and then reversing based on the parking start position, the parking target position, and the reverse trajectory profile selected by the trajectory selection unit; and a path output unit that outputs the parking path determined by the path determination unit.

[0007] In a parking path generation device according to an aspect of the present invention, a plurality of reverse path patterns based on the rear axle of the trailer are stored in advance for each wheelbase type of the trailer. When a parking path is generated, a plurality of reverse trajectory profiles corresponding to the wheelbase type of the trailer in the articulated vehicle are specified, and a plurality of reverse trajectory profiles are generated based on the specified plurality of reverse trajectory profiles. Among the plurality of reverse trajectory profiles generated in this way, a reverse trajectory profile that does not collide with surrounding obstacles is selected, and a parking path is determined from the selected reverse trajectory profile, the parking start position, and the parking target position. In the parking path of the articulated vehicle, particularly when reversing, the movement becomes complicated. For this reason, in generating the parking path of the articulated vehicle, it is difficult to generate the reverse path with high accuracy, and there is a problem that the calculation cost increases in order to generate it with high accuracy as much as possible. In this regard, in the parking path generation device according to an aspect of the present invention, a plurality of reverse path patterns are stored in advance for each wheelbase type of the trailer, and a reverse trajectory profile is selected from among these pre-stored pieces of information, so that the calculation cost can be significantly reduced. In addition, since a plurality of reverse path patterns are stored for each wheelbase type of the trailer, the reverse path can be generated with high accuracy (high reproducibility) according to the type of the trailer connected to the tractor. As described above, according to the parking path generation device according to the positional aspect of the present invention, the parking path of the articulated vehicle can be generated with high accuracy and low calculation cost.

[0008] The path determination unit determines a reverse start position at which the articulated vehicle starts to reverse based on the parking target position and the reverse trajectory profile selected by the trajectory selection unit, and determines a path that reaches the parking target position along the selected reverse trajectory profile from the reverse start position as the reverse path. After determining the reverse path, based on the parking start position, the reverse start position, and the information on the obstacle, it determines a forward path by which the articulated vehicle that has started to move forward from the parking start position reaches the reverse start position without colliding with the obstacle, and determines a parking path based on the forward path and the reverse path. For example, when the forward path is determined first and then the reverse path is determined in the order of the actual driving path, constraints regarding the forward path occur in the determination of the reverse path, and for example, the vehicle posture may bend when reaching the parking target position. Such problems occur more significantly in an articulated vehicle with a coupling angle. In this regard, by determining the reverse path first and then the forward path (determining the path in reverse order from the parking target position), there are no constraints regarding the forward path when determining the reverse path, so it is possible to suppress the vehicle posture from bending during parking and generate an ideal parking path.

[0009] When there are multiple reverse trajectory profiles that do not collide with the obstacle, the path determination unit may determine the parking path based on one reverse trajectory profile with the smallest degree of change in curvature in the path among the multiple reverse trajectory profiles that do not collide with the obstacle. As a result, a path with as few steering operations as possible for the reverse path is selected, so it is possible to suppress the discomfort of the driver during reverse.

Advantages of the Invention

[0010] According to one aspect of the present invention, it is possible to generate the parking path of the articulated vehicle with high accuracy and low computational cost.

Brief Description of the Drawings

[0011]

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Best Mode for Carrying Out the Invention

[0012] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each figure, the same or corresponding parts are denoted by the same reference numerals, and redundant explanations are omitted.

[0013] FIG. 1 is a block diagram schematically showing a parking control device equipped with a parking path generation device according to an embodiment of the present invention. In FIG. 1, the parking control device 1 of the present embodiment is a device for automatically parking the coupled vehicle 2 in a parking lot or the like, as shown in FIGS. 2 and 3.

[0014] The articulated vehicle 2 is a large semi-trailer truck here. Note that the articulated vehicle 2 may also be a medium-sized truck or a small-sized truck. The articulated vehicle 2 includes a tractor 3 and a trailer 4 disposed on the rear side of the tractor 3. The trailer 4 is rotatably connected to the tractor 3 at the connecting portion 5.

[0015] The tractor 3 has a vehicle body 6, a pair of left and right front wheels 7 rotatably supported on the front side of the vehicle body 6, and a pair of left and right rear wheels 8 rotatably supported on the rear side of the vehicle body 6. An engine (not shown) is mounted on the tractor 3. The trailer 4 has a vehicle body 9 and a pair of left and right wheels 10 rotatably supported on the rear side of the vehicle body 9.

[0016] Returning to FIG. 1, the parking control device 1 is mounted on the tractor 3 of the articulated vehicle 2. The parking control device 1 includes a car navigation 11, a coupling angle sensor 12, a camera 13, a path generation ECU 14, and a parking control ECU 15.

[0017] The car navigation 11, the coupling angle sensor 12, the camera 13, and the path generation ECU 14 constitute the parking path generation device 16 of the present embodiment. The parking path generation device 16 is a device that generates a parking path for parking the articulated vehicle 2 by the parking control device 1.

[0018] As shown in FIG. 3, the parking path generation device 16 generates a parking path that advances from the side of the parking space H, makes one U-turn, and then reverses to the parking space H. Specifically, the parking path generation device 16 generates a parking path that advances from the parking start position A1 to the turning position A3 (the reverse start position) and then reverses from the turning position A3 to the parking target position A2. The parking start position A1, the parking target position A2, and the turning position A3 will be described in detail later.

[0019] The car navigation device 11 includes a GPS receiver 17 that receives radio waves transmitted from GPS satellites to measure the current position of the articulated vehicle 2, a map storage unit 18 that stores map data, a display 19 that displays the current position of the articulated vehicle 2 together with a map, and an input unit 20 that sets and inputs data such as the destination of the articulated vehicle 2.

[0020] The GPS receiver 17 constitutes a position detection unit that detects the current position of the articulated vehicle 2. The GPS receiver 17 detects the position coordinates and azimuth angle of the two-dimensional coordinates (X, Y coordinates) of the tractor 3 as the current position of the articulated vehicle 2.

[0021] The coupling angle sensor 12 is a sensor that detects the coupling angle between the tractor 3 and the trailer 4. The coupling angle is the angle at which a virtual line extending in the longitudinal direction of the tractor 3 intersects a virtual line extending in the longitudinal direction of the trailer 4. When the tractor 3 and the trailer 4 are arranged on the same straight line, the coupling angle is 0 degrees.

[0022] The camera 13 is an imaging unit that images the surroundings of the articulated vehicle 2. The camera 13 is provided on, for example, the tractor 3 and the trailer 4 respectively. The camera 13 constitutes an environment detection unit that detects the surrounding environment of the articulated vehicle 2, such as the presence or absence of an obstacle 50 (Fig. 3).

[0023] Examples of the obstacle 50 include other parked vehicles 51 (see Fig. 3 etc.), the wall 52 of a building (see Fig. 7 etc.), or a curb. When the wall 52 of the building can be recognized from the map data built into the car navigation device 11, the map storage unit 18 of the car navigation device 11 also constitutes the above-described environment detection unit.

[0024] The route generation ECU 14 is composed of a CPU, a RAM, a ROM, an input / output interface, etc. The route generation ECU 14 inputs the information of the car navigation device 11, the detection value of the coupling angle sensor 12, and the captured image of the camera 13, executes processing related to the generation of the parking route of the articulated vehicle 2, and outputs data including the parking route of the articulated vehicle 2 to the parking control ECU 15.

[0025] The path generation ECU 14 includes a pattern storage unit 21, a position setting unit 22, a trajectory generation unit 23, a trajectory selection unit 24, a path determination unit 25, and a path output unit 26.

[0026] The pattern storage unit 21 stores a plurality of reverse path patterns based on the rear axle of the trailer 4 for each wheelbase length (wheelbase type) of the trailer 4. The pattern storage unit 21 groups, for example, a plurality of types of trailers 4 that can be connected to the tractor 3 for each predetermined range of the wheelbase length, and stores a plurality of reverse path patterns for each group. Specifically, the pattern storage unit 21 divides, for example, into a group of trailers 4 with a wheelbase length of 6 m or less, a group of trailers 4 with a wheelbase length greater than 6 m and 8 m or less, and a group of trailers 4 with a wheelbase length greater than 8 m and 10 m or less, and stores a plurality of reverse path patterns for each group.

[0027] Each of the plurality of reverse path patterns is a trajectory that the rear axle of the trailer 4 with the corresponding wheelbase length can actually take during reverse. The trajectory of the reverse path pattern is shown by a curve with a continuously changing curvature. The reverse path pattern is the reverse trajectory profile of the center of the rear axle of the trailer 4 when the articulated vehicle 2 turns with the most space saving. The plurality of reverse path patterns belonging to the same group of wheelbase lengths have different degrees of change in curvature in the path. The plurality of reverse path patterns shown in FIG. 4 show a plurality of reverse path patterns belonging to the same group of wheelbase lengths, and seven reverse path patterns with different degrees of change in curvature in the path are shown as reverse path patterns heading towards the common parking target position A2. In the example shown in FIG. 4, the reverse path patterns are shown at 15° intervals in the range of 0° to 90° with respect to the parking target position A2. As shown in FIG. 4, the plurality of reverse path patterns are more likely to be selected in the subsequent trajectory selection, that is, the priority may be higher, the smaller the degree of change in curvature.

[0028] As shown in Fig. 5, the groups of trailers 4 with a wheelbase length of 6 m or less (see Fig. 5(a)), the groups of trailers 4 with a wheelbase length greater than 6 m and 8 m or less (see Fig. 5(b)), and the groups of trailers 4 with a wheelbase length greater than 8 m and 10 m or less (see Fig. 5(c)) each have different multiple reverse path patterns (trajectory profiles). In the parking path generation device 16 according to the present embodiment, since the reverse path is generated based on the reverse path pattern close to the wheelbase length of the actual trailer 4, the reverse path can be generated with high accuracy (high reproducibility).

[0029] Note that, for example, a trochoid is used for the design of the reverse path pattern. However, since the generation of the reverse path pattern is performed by offline calculation, it may be generated by a method with a higher load than the trochoid.

[0030] The position setting unit 22 sets the parking start position A1 and the parking target position A2 of the articulated vehicle 2 based on information including the current position of the articulated vehicle 2. The position setting unit 22 uses the current position of the articulated vehicle 2 detected by the GPS receiver 17 of the car navigation 11 to set the parking start position A1 (see Fig. 3) of the articulated vehicle 2. Specifically, the position setting unit 22 sets the parking start position A1 of the articulated vehicle 2 based on the current position of the articulated vehicle 2 and the connection angle θ between the tractor 3 and the trailer 4 detected by the connection angle sensor 12. The position setting unit 22 acquires, for example, the position coordinates, azimuth angle, and turning curvature of the trailer 4 as the parking start position A1 of the articulated vehicle 2.

[0031] The position setting unit 22 sets the parking target position A2 (see FIG. 3) of the articulated vehicle 2 using the information of the car navigation 11 including the current position of the articulated vehicle 2 detected by the GPS receiver 17. Specifically, the position setting unit 22 sets the parking target position A2 of the articulated vehicle 2 based on the information of the car navigation 11 including the current position of the articulated vehicle 2, the coupling angle θ between the tractor 3 and the trailer 4 detected by the coupling angle sensor 12, and the captured image of the camera 13. Note that the parking target position A2 may be input as coordinate information from outside the system by an external instruction (such as a driver's HMI operation, an instruction from control, etc.) or an autonomous parking space detection in the upper processing layer of the automatic driving system. The position setting unit 22 acquires, for example, the position coordinates, azimuth angle, and turning curvature of the trailer 4 as the parking target position A2 of the articulated vehicle 2. Details of the processing of the position setting unit 22 will be described later.

[0032] The trajectory generation unit 23 generates a plurality of reverse trajectory profiles. Based on the information indicating the wheelbase length of the trailer 4 in the articulated vehicle 2 and the information stored in the pattern storage unit 21 (a plurality of reverse path patterns for each wheelbase length of the trailer 4), the trajectory generation unit 23 identifies a plurality of reverse path patterns corresponding to the wheelbase length of the trailer 4 in the articulated vehicle 2. That is, the trajectory generation unit 23 identifies a plurality of reverse path patterns corresponding to the wheelbase length of the trailer 4 for which the reverse trajectory profile is to be generated. Information such as the wheelbase length of the trailer 4 may be obtained, for example, by providing the trailer 4 with an ID tag and reading the ID tag, or may be estimated by image processing when the wheels are imaged by a camera mounted on the tractor 3 side. For example, in the example shown in FIG. 5, if the wheelbase length of the trailer 4 is 7 m, a plurality of reverse path patterns shown in FIG. 5(b) are identified (extracted). Then, the trajectory generation unit 23 generates a plurality of reverse trajectory profiles based on the identified plurality of reverse path patterns. Specifically, the trajectory generation unit 23 generates a reverse trajectory profile (tractor reverse trajectory) indicating the reverse trajectory of the tractor 3 from a plurality of reverse trajectory profiles based on the rear axle of the trailer 4. Details of the processing of the trajectory generation unit 23 will be described later.

[0033] The trajectory selection unit 24 selects a reverse trajectory profile in which the articulated vehicle 2 does not collide with an obstacle based on the parking target position A2, information on obstacles 50 around the articulated vehicle 2, and the plurality of reverse trajectory profiles (tractor reverse trajectories) generated by the trajectory generation unit 23. Information on the obstacles 50 around the articulated vehicle 2 is obtained from the camera 13 that can function as an environment detection unit and the map storage unit 18 of the car navigation 11. The trajectory selection unit 24 selects one or a plurality of reverse trajectory profiles in which the trajectory does not overlap with the obstacle 50 (that is, the vehicle body 9 of the trailer 4 or the vehicle body 6 of the tractor 3 does not collide with the obstacle 50) from among the plurality of reverse trajectory profiles (tractor reverse trajectories) leading to the parking target position A2. Details of the processing of the trajectory selection unit 24 will be described later.

[0034] Based on the parking target position A2 and the reverse trajectory profile selected by the trajectory selection unit 24, the path determination unit 25 determines a parking path such that the articulated vehicle 2 that starts parking from the parking start position A1 parks at the parking target position A2 by moving forward and then backward.

[0035] First, based on the parking target position A2 and the reverse trajectory profile selected by the trajectory selection unit 24, the path determination unit 25 determines a turning-back position A3 (reverse start position) where the articulated vehicle 2 starts to reverse. Then, from the turning-back position A3, the path determination unit 25 determines a path along the selected reverse trajectory profile to reach the parking target position A2 as the reverse path.

[0036] After determining the above-described reverse path, based on the parking start position A1, the turning-back position A3, and the information of the obstacle 50, the path determination unit 25 determines a forward path for the articulated vehicle 2 that starts moving forward from the parking start position A1 to reach the turning-back position A3 without colliding with the obstacle 50. Then, the path determination unit 25 determines the parking path by combining the forward path and the reverse path.

[0037] When there are multiple reverse trajectory profiles selected by the trajectory selection unit 24, for each of them, the turning-back position A3 is determined, and the reverse path and the forward path are determined. When there are multiple reverse trajectory profiles selected by the trajectory selection unit 24, the path determination unit 25 may determine the reverse path of the parking path based on one reverse trajectory profile with the smallest degree of change in curvature in the path among the multiple reverse trajectory profiles.

[0038] The path determination unit 25 uses the geometric model of the articulated vehicle 2 to perform a vehicle motion simulation for performing follow-up control on the articulated vehicle 2 from the parking start position A1 and the parking target position A2 to the turning-back position A3 by forward driving, thereby calculating a data series of the steering angle of the tractor 3 and a data series of the respective attitude angles of the tractor 3 and the trailer 4. Note that the data series is historical data.

[0039] The route output unit 26 outputs the data of the parking route (parking route data) determined by the route determination unit 25 to the parking control ECU 15. Further, the route output unit 26 outputs the data series of the steering angle of the tractor 3 and the data series of the respective attitude angles of the tractor 3 and the trailer 4 to the parking control ECU 15.

[0040] The parking control ECU 15 is composed of a CPU, a RAM, a ROM, an input / output interface, etc. The parking control ECU 15 inputs the parking route data and data series from the route generation ECU 14, the information of the car navigation 11, and the detection value of the coupling angle sensor 12, and executes processing related to the automatic parking of the coupled vehicle 2.

[0041] The parking control ECU 15 has a storage unit 31 and a following control unit 32. The storage unit 31 stores the parking route data and data series output from the route output unit 26 of the route generation ECU 14.

[0042] The following control unit 32 performs steering control and speed control of the coupled vehicle 2 so as to park the coupled vehicle 2 at the parking target position A2 according to the parking route data and data series stored in the storage unit 31. In the steering control of the coupled vehicle 2, the following control unit 32 controls the steering of the coupled vehicle 2, and in the speed control of the coupled vehicle 2, the following control unit 32 controls the accelerator and the brake.

[0043] At this time, the following control unit 32 performs feedforward control of the steering of the tractor 3 so as to park the coupled vehicle 2 at the parking target position A2 according to the data series of the steering angle of the tractor 3 and the data series of the respective attitude angles of the tractor 3 and the trailer 4. That is, the following control unit 32 performs feedforward control of the steering of the tractor 3 using the data series of the steering angle of the tractor 3 and the data series of the respective attitude angles of the tractor 3 and the trailer 4 as target values. Further, the following control unit 32 performs feedback control of the steering of the tractor 3 so as to park the coupled vehicle 2 at the parking target position A2 based on the coupling angle θ between the tractor 3 and the trailer 4 detected by the coupling angle sensor 12 and the current position of the coupled vehicle 2 detected by the GPS receiver 17.

[0044] The tracking control unit 32 virtually considers a vehicle with a target attitude on the target path of the trailer 4 given by, for example, a trochoid curve, and performs tracking control to bring the relative error of the actual vehicle with respect to the target value closer to 0 using the error state quantity. Examples of tracking control for bringing the error state quantity closer to 0 include LQ control.

[0045] Next, with reference to FIG. 6, the procedure of the path generation process will be described in detail. FIG. 6 is a flowchart showing the details of the path generation process executed by the path generation ECU 14. This process is executed when the driver of the articulated vehicle 2 instructs the start of parking support. At this time, the driver may set and input a parking target position candidate for the articulated vehicle 2 through the input unit 20 of the car navigation 11.

[0046] As shown in FIG. 6, the path generation ECU 14 sets a virtual parking mass at the parking target position A2 (step S1). As a prerequisite for this process, the path generation ECU 14 first acquires the position coordinates, azimuth angle, and turning curvature of the trailer 4 as the parking start position A1 of the coupled vehicle 2 based on the information of the car navigation 11 including the GPS receiver 17 and the detection value of the coupling angle sensor 12. The position coordinates of the trailer 4 are, for example, the position coordinates of the center of the rear axle of the trailer 4. The center of the rear axle of the trailer 4 is the center in the axial direction (the vehicle width direction of the trailer 4) of the axle 10a connected to a pair of left and right wheels 10 arranged on the rear side of the trailer 4, as shown in FIG. 3. The azimuth angle of the trailer 4 corresponds to the yaw angle of the trailer 4. Note that the azimuth angle of the tractor 3 corresponds to the yaw angle of the tractor 3. Also, under the condition of assuming a steady turn of the coupled vehicle 2, the turning curvature of the trailer 4 uniquely corresponds to the coupling angle of the trailer 4 with respect to the tractor 3. For this reason, the coupling angle θ between the tractor 3 and the trailer 4 is obtained by an algebraic expression taking the turning curvature of the trailer 4 as an input. Therefore, the turning curvature of the trailer 4 is obtained from the coupling angle θ between the tractor 3 and the trailer 4. When the coupling angle θ between the tractor 3 and the trailer 4 is 0 degrees, the turning curvature of the trailer 4 is 0. Further, the path generation ECU 14 sets the position coordinates, azimuth angle, and turning curvature of the trailer 4 as the parking target position A2 of the coupled vehicle 2 based on the information of the car navigation 11 including the GPS receiver 17, the detection value of the coupling angle sensor 12, and the captured image of the camera 13.

[0047] As shown in FIG. 7, the path generation ECU 14 sets virtual walls V1 to V3 that constitute a virtual parking mass surrounding three sides of the parking target position A2. In the example shown in FIG. 7, the virtual walls V1 and V2 are virtual walls surrounding the side surfaces of the coupled vehicle 2, and the virtual wall V3 is a virtual wall surrounding the rear part of the coupled vehicle 2. The path generation ECU 14 sets a reverse path, which will be described later, so as not to contact the virtual walls V1 to V3.

[0048] Subsequently, the path generation ECU 14 generates a plurality of reverse trajectory profiles (tractor reverse trajectories) indicating the reverse trajectory of the tractor 3 (step S2). The path generation ECU 14 first identifies a plurality of reverse path patterns corresponding to the wheelbase length of the trailer 4 in the articulated vehicle 2 based on the information indicating the wheelbase length of the trailer 4 in the articulated vehicle 2 and the information stored in the pattern storage unit 21 (a plurality of reverse path patterns for each wheelbase length of the trailer 4). That is, the path generation ECU 14 identifies a plurality of reverse path patterns corresponding to the wheelbase length of the trailer 4 for which the reverse trajectory profile is to be generated (see the upper diagram in FIG. 8). Such a reverse path pattern is generated by adopting a trochoid curve as a curve in which the curvature continuously changes from the initial position to the target position.

[0049] The trochoid curve is a curve in which a sudden change in curvature does not occur. The trochoid curve is a smooth curve that can arbitrarily specify the initial and terminal curves and positions by combining three cycloid curves with equal path lengths. The trochoid curve can be easily obtained by numerically solving a two-variable non-linear equation. Note that the trochoid curve is described in detail in the "Path Generation Method with Specifiable Initial and Terminal Curvatures by Cycloid Curves" in the Transactions of the Japan Society of Mechanical Engineers (Vol. 85, No. 878, 2019).

[0050] Then, based on the identified multiple reverse path patterns, the path generation ECU 14 generates a plurality of reverse trajectory profiles. Specifically, the path generation ECU 14 generates a reverse trajectory profile (tractor reverse trajectory) indicating the reverse trajectory of the tractor 3 from a plurality of reverse trajectory profiles based on the rear axle of the trailer 4. In the upper figure at the lower part of FIG. 8, the trajectory of the rear axle of the trailer 4 is shown by a solid line, and the trajectory of the rear axle of the tractor 3 is shown by a dashed line. The path generation ECU 14 derives the trajectory of the rear axle of the tractor 3 shown by the dashed line based on the trajectory of the rear axle of the trailer 4 shown by the solid line and the dimensions of the vehicle body 9 of the trailer 4 and the like. Then, as shown in the lower figure at the lower part of FIG. 8, the path generation ECU 14 derives the trajectory of the entire articulated vehicle 2 based on the trajectory of the rear axle of the trailer 4 and the trajectory of the rear axle of the tractor 3. As shown in the lower part of FIG. 8, the path generation ECU 14 generates a reverse trajectory profile for each of the multiple reverse path patterns.

[0051] Subsequently, for each reverse trajectory profile, the path generation ECU 14 moves (adjusts) the position so as to fit within the virtual walls V1 to V3 that constitute the virtual parking mass (step S3). As shown in FIGS. 9(a) and 9(b), the reverse trajectory profile is moved in the Y-axis (vertical) direction to find a position where it does not collide with the virtual parking mass. FIG. 9(a) is a diagram in which the reverse trajectory profile is largely moved in the - direction of the Y-axis, and FIG. 9(b) is a diagram in which the reverse trajectory profile is largely moved in the + direction of the Y-axis. The path generation ECU 14 sets the reverse trajectory profile at a position that does not collide with the virtual parking mass and is as close as possible to the parking target position A2, for example, by means of a binary search method. Then, as shown in FIG. 9(c), when the position of the reverse trajectory profile is determined, the path generation ECU 14 corrects the trajectory so as to add a straight line section to the goal (parking target position A2).

[0052] Subsequently, the path generation ECU 14 performs a collision determination regarding the reverse path of the articulated vehicle 2 based on the obstacle map (step S4). The obstacle map is information indicating the positions of the obstacles 50 acquired from the map storage unit 18 of the camera 13 and the car navigation 11 that can function as an environment detection unit. The path generation ECU 14 determines whether the articulated vehicle 2 collides with the obstacle 50 (whether the obstacle 50 exists on the trajectory) for a plurality of reverse trajectory profiles (tractor reverse trajectories) reaching the parking target position A2. In the example shown in FIG. 10, among the seven reverse trajectory profiles C1 to C7, the reverse trajectory profiles C1 to C3 collide with the building wall 52 which is the obstacle 50. In this case, the path generation ECU 14 excludes the reverse trajectory profiles C1 to C3 and leaves (selects) the other reverse trajectory profiles C4 to C7 as candidate paths for the reverse path.

[0053] Subsequently, the path generation ECU 14 determines a turning-back position A3 (reverse start position) at which the articulated vehicle 2 starts to reverse based on the parking target position A2 and the reverse trajectory profile selected by the trajectory selection unit 24. Then, the path generation ECU 14 generates a forward path of the tractor trajectory based on the parking start position A1 and the turning-back position A3 (step S5).

[0054] Subsequently, the path generation ECU 14 performs a collision determination regarding the forward path of the articulated vehicle 2 based on the obstacle map (step S6). The obstacle map is information indicating the positions of the obstacles 50 acquired from the map storage unit 18 of the camera 13 and the car navigation 11 that can function as an environment detection unit. The path generation ECU 14 determines whether the articulated vehicle 2 collides with the obstacle 50 (whether the obstacle 50 exists on the trajectory) for a plurality of forward trajectory profiles (tractor forward trajectories) from the parking start position A1 to the turning-back position A3. In the example shown in FIG. 11, the forward trajectory profile does not collide with the building wall 52 or the like which is the obstacle 50. In this way, the path generation ECU 14 specifies the candidate path for the forward path.

[0055] Then, when there are multiple candidate routes, the route generation ECU 14 determines one final route from the candidate routes based on a pre-set priority order. In the example shown in FIG. 12, reverse trajectory profiles C4 to C7 are selected as candidate routes for the reverse route. In this case, the route generation ECU 14 determines, for example, the reverse trajectory profile C4 with the smallest degree of change in curvature in the route among the multiple reverse trajectory profiles C4 to C7 as the final route of the reverse route. Then, for the forward route, it is also determined as the forward route continuous with the reverse trajectory profile C4.

[0056] Finally, the route generation ECU 14 performs a vehicle motion simulation in which the articulated vehicle 2 is controlled to follow in a forward travel from the parking start position A1 and the parking target position A2 to the turning position A3 using the geometric model of the articulated vehicle 2, thereby calculating the data series of the steering angle of the tractor 3 and the data series of the respective attitude angles of the tractor 3 and the trailer 4. Note that the data series is historical data.

[0057] Next, the operation and effect of the parking route generation device 16 according to this embodiment will be described.

[0058] The parking path generation device 16 according to this embodiment is a parking path generation device that generates a parking path for parking the articulated vehicle 2 including the tractor 3 and the trailer 4. For each wheelbase length of the trailer 4, a plurality of reverse path patterns based on the rear axle of the trailer 4, and a plurality of reverse path patterns with different degrees of curvature change in the path are stored in the pattern storage unit 21. Based on the information including the current position of the articulated vehicle 2, a position setting unit 22 that sets the parking start position A1 of the articulated vehicle 2 and the parking target position A2 of the articulated vehicle 2. Based on the information indicating the wheelbase length of the trailer 4 in the articulated vehicle 2 and the information stored in the pattern storage unit 21, a plurality of reverse path patterns corresponding to the wheelbase length of the trailer 4 in the articulated vehicle 2 are specified, and based on the specified plurality of reverse path patterns, a trajectory generation unit 23 that generates a plurality of reverse trajectory profiles. Based on the parking target position A2, the information of the obstacles 50 around the articulated vehicle 2, and the plurality of reverse trajectory profiles, a trajectory selection unit 24 that selects a reverse trajectory profile in which the articulated vehicle 2 does not collide with the obstacles 50. Based on the parking start position A1, the parking target position A2, and the reverse trajectory profile selected by the trajectory selection unit 24, a path determination unit 25 that determines a parking path so that the articulated vehicle 2 that starts parking from the parking start position A1 is parked at the parking target position A2 by moving forward and then reversing. And a path output unit 26 that outputs the parking path determined by the path determination unit 25.

[0059] In the parking path generation device 16 according to this embodiment, a plurality of reverse path patterns based on the rear axle of the trailer 4 are stored in advance for each wheelbase length of the trailer 4. When a parking path is generated, a plurality of reverse trajectory profiles corresponding to the wheelbase length of the trailer 4 in the articulated vehicle 2 are specified, and a plurality of reverse trajectory profiles are generated based on the specified plurality of reverse trajectory profiles. Among the plurality of reverse trajectory profiles generated in this way, a reverse trajectory profile that does not collide with the surrounding obstacle 50 is selected, and a parking path is determined from the selected reverse trajectory profile, the parking start position A1, and the parking target position A2. In the parking path of the articulated vehicle 2, particularly when reversing, the movement becomes complicated. For this reason, in generating the parking path of the articulated vehicle 2, it is difficult to generate the reverse path with high precision, and also, the problem is that the calculation cost increases in order to generate it with high precision as much as possible. In this regard, in the parking path generation device 16 according to this embodiment, a plurality of reverse path patterns are stored in advance for each wheelbase length of the trailer 4, and since a reverse trajectory profile is selected from these pre-stored pieces of information, the calculation cost can be significantly reduced. Further, since a plurality of reverse path patterns are stored for each wheelbase length of the trailer 4, the reverse path can be generated with high precision (high reproducibility) according to the type of the trailer 4 connected to the tractor. As described above, according to the parking path generation device 16 according to this embodiment, the parking path of the articulated vehicle 2 can be generated with high precision and at low calculation cost.

[0060] The path determination unit 25 determines a turning-back position A3, which is a reverse start position where the articulated vehicle 2 starts to reverse, based on the parking target position A2 and the reverse trajectory profile selected by the trajectory selection unit 24, and determines, as a reverse path, a path that reaches the parking target position A2 along the selected reverse trajectory profile from the turning-back position A3. After determining the reverse path, based on the parking start position A1, the turning-back position A3, and the information on the obstacle 50, the path determination unit 25 determines a forward path for the articulated vehicle 2 that starts to move forward from the parking start position A1 and reaches the turning-back position A3 without colliding with the obstacle 50, and may determine a parking path based on the forward path and the reverse path. For example, when the forward path is determined first and then the reverse path is determined in the order of the actual driving path, constraints regarding the forward path may occur in the determination of the reverse path. For example, the vehicle posture may bend when reaching the parking target position. FIG. 13 is a diagram for explaining the generation of a parking path according to a comparative example. In the example shown in FIG. 13, the forward path is determined first and then the reverse path is determined, and the vehicle posture of the articulated vehicle 2 is bent when reaching the parking target position. Such a problem occurs more significantly in the articulated vehicle 2 with a connection angle. In this regard, by determining the reverse path first and then the forward path (determining the path in reverse order from the parking target position A2), there are no constraints regarding the forward path when determining the reverse path, so it is possible to suppress the bending of the vehicle posture during parking and generate an ideal parking path.

[0061] When there are a plurality of reverse trajectory profiles that do not collide with the obstacle 50, the path determination unit 25 may determine the parking path based on one reverse trajectory profile with the smallest degree of change in curvature in the path among the plurality of reverse trajectory profiles that do not collide with the obstacle 50. Thereby, a path with as few steering operations as possible is selected for the reverse path, so that the discomfort of the driver during reverse can be suppressed.

[0062] As described above, embodiments of the present invention have been explained, but the present invention is not limited to the above embodiments. For example, in the above embodiment, the current position of the coupled vehicle 2 is measured by the GPS receiver 17 of the car navigation 11. However, the position detection unit for detecting the current position of the coupled vehicle 2 is not particularly limited to the GPS receiver 17. For example, the current position of the coupled vehicle 2 may be estimated by using a laser SLAM method that irradiates a laser around the coupled vehicle 2 and utilizes data from a laser sensor that receives the reflected light of the laser, or by using a Visual SLAM method that utilizes an imaging image of a camera.

[0063] Also, in the above embodiment, the obstacle 50 existing around the coupled vehicle 2 is detected by using the camera 13. However, it is not particularly limited to that form, and the obstacle 50 around the coupled vehicle 2 may be detected by using a laser sensor, a radar sensor, etc. instead of or together with the camera 13.

[0064] Also, in the above embodiment, a trochoid curve is adopted to generate the target path of the trailer 4. However, it is not particularly limited to that form, and a curve whose curvature continuously changes between the initial position and the target position of the trailer 4 may be adopted. Examples of such curves include Biarc curve, Clothoid curve, Bezier curve, and Spline curve.

[0065] Also, in the above embodiment, the coupled vehicle 2 is a semi-trailer type truck, but the present invention is also applicable to a full-trailer type truck. Further, the present invention is not particularly limited to trucks and is also applicable to coupled vehicles such as buses.

[0066] Also, the parking path generation device 16 of the above embodiment is provided in a travel control device that reverses the coupled vehicle 2 by automatic driving. However, the present invention is not particularly limited to that form and is also applicable to a case where the reverse parking of the coupled vehicle 2 is manually performed using a parking assistance system.

[0067] Further, although the parking route generation device 16 of the above embodiment is applied to a parking support system that supports the reverse parking of the articulated vehicle 2, the present invention is not limited to the reverse parking of the articulated vehicle 2 in particular, and can also be applied to forward driving such as right and left turns at intersections, for example.

Explanation of Signs

[0068] 2... Articulated vehicle, 3... Tractor, 4... Trailer, 16... Parking route generation device, 21... Pattern storage unit, 22... Position setting unit, 23... Trajectory generation unit, 24... Trajectory selection unit, 25... Route determination unit, 26... Route output unit, 50... Obstacle, A1... Parking start position, A2... Parking target position, A3... Turning-back position (reverse start position).

Claims

1. A parking path generation device for generating a parking path for parking a coupled vehicle including a tractor and a trailer, a pattern storage unit that stores, for each wheelbase type of the trailer, a plurality of reverse path patterns based on the rear axle of the trailer, the plurality of reverse path patterns having different degrees of change in curvature in the path; a position setting unit that sets a parking start position and a parking target position of the coupled vehicle based on information including the current position of the coupled vehicle; a trajectory generation unit that identifies the plurality of reverse path patterns corresponding to the wheelbase type of the trailer in the coupled vehicle based on information indicating the wheelbase type of the trailer in the coupled vehicle and information stored in the pattern storage unit, and generates a plurality of reverse trajectory profiles based on the identified plurality of reverse path patterns; a trajectory selection unit that selects a reverse trajectory profile in which the coupled vehicle does not collide with an obstacle based on the parking target position, information on obstacles around the coupled vehicle, and the plurality of reverse trajectory profiles; a path determination unit that determines a parking path based on the parking start position, the parking target position, and the reverse trajectory profile selected by the trajectory selection unit such that the coupled vehicle that starts parking from the parking start position parks at the parking target position by moving forward and then reversing; and a path output unit that outputs the parking path determined by the path determination unit. A parking path generation device.

2. The path determination unit, based on the parking target position and the reverse trajectory profile selected by the trajectory selection unit, determines a reverse start position at which the coupled vehicle starts to reverse, and determines a path from the reverse start position to reach the parking target position along the selected reverse trajectory profile as a reverse path, After determining the reverse path, based on the parking start position, the reverse start position, and the information of the obstacle, a forward path is determined for the articulated vehicle that has started moving forward from the parking start position to reach the reverse start position without colliding with the obstacle. The parking path generation device according to claim 1, wherein the parking path is determined based on the forward path and the reverse path.

3. When there are a plurality of reverse trajectory profiles that do not collide with the obstacle, the path determination unit determines the parking path based on one reverse trajectory profile having the smallest degree of change in curvature in the path among the plurality of reverse trajectory profiles that do not collide with the obstacle. The parking path generation device according to claim 1 or 2.

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