JP2010100086A - Parking assist device and method for determining contact with obstacle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily determine whether there is a possibility that a vehicle is brought into contact with an obstacle when the vehicle moves along a parking path. <P>SOLUTION: At least a part of a parking path for guiding a vehicle to the target parking position is approximated by a circular arc CA, and the contact possibility of the vehicle with an obstacle PV during the parking action of the vehicle is determined based on the locus of the circular arc CA. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a parking assistance device and an obstacle contact determination method for assisting a parking operation by calculating a parking route for guiding a vehicle to a parking target position.

Conventionally, as a parking assistance device that supports a parking operation of a vehicle, a parking route that guides the vehicle to a set parking target position is calculated, and the vehicle is steered so that the vehicle can appropriately move along the calculated parking route. A device that performs automatic control is known (for example, see Patent Document 1). In the parking assist device described in Patent Document 1, a series of parking routes is calculated by combining a route in which the steering angle of the vehicle changes and a route in which the steering angle is constant, and the vehicle moves along the parking route. The steering of the vehicle is automatically controlled so that it can be done. Further, when the vehicle approaches an obstacle such as another vehicle existing ahead of the parking target position in the parking process, an approach warning is issued to alert the vehicle driver.
JP 2004-352120 A

  By the way, when guiding a vehicle along a parking route, in order to surely avoid the vehicle from contacting an obstacle in the middle of the parking route, the possibility of contact with the obstacle is calculated at the stage of calculating the parking route. It is desirable to be able to judge. However, as described in Patent Document 1, for example, when a series of routes in which a route in which the steering angle of the vehicle changes and a route in which the steering angle is constant is calculated as a parking route, etc. In addition, since the parking route is a route calculated by repeated calculation, in order to appropriately determine the possibility of contact with an obstacle at the stage of calculating the parking route, it is necessary to perform determination for the number of repeated calculations. There is a problem that the processing load increases.

  The present invention has been made in view of the above-described conventional situation, and can easily determine whether or not there is a possibility of contact with an obstacle when the vehicle moves along the parking route. An object of the present invention is to provide a parking assist device and an obstacle contact determination method.

  The present invention approximates at least a part of the parking route calculated as a route for guiding the vehicle to the parking target position with an arc, and the obstacle occurs when the vehicle moves along the parking route based on the obtained arc trajectory. The above-mentioned problem is solved by determining whether there is a possibility of contact with an object.

  According to the present invention, since the possibility of contact with an obstacle during the parking operation of the vehicle is determined based on an arc trajectory approximating the parking route, the possibility of contact with the obstacle can be determined very simply. Can do.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

[Outline of parking assistance device]
FIG. 1 is a block diagram showing a functional configuration of a parking assistance apparatus to which the present invention is applied. This parking assist device calculates a parking route for guiding a vehicle to a parking target position, and performs steering control of the vehicle so that the vehicle moves along the calculated guidance route. As shown in FIG. 1, the vehicle includes a parking target position setting unit 1, a parking route calculation unit 2, an obstacle detection unit 3, a contact determination unit 4, and a steering control unit 5. Among these functional configurations, the parking target position setting unit 1, the parking route calculation unit 2, the contact determination unit 4, and the steering control unit 5, for example, use a dedicated ECU (electric control unit) for parking assistance, This can be realized by installing software for executing each function in the ECU. Moreover, the parking route calculation part 2 can also be implement | achieved by the software mounted in ECU for navigation as one function of a vehicle-mounted navigation apparatus. The obstacle detection unit 3 can be realized by using, for example, an ultrasonic sonar or a radar.

  The parking target position setting unit 1 sets the parking target position of the vehicle. For example, when a vehicle-mounted camera is mounted on the vehicle, the parking target position is detected by performing image processing on a captured image of the vehicle-mounted camera to detect a parking available space around the vehicle. The parking target position may be automatically set in the parking available space, or the captured image of the in-vehicle camera is displayed on the monitor, and the parking target position is set at the position selected by the vehicle occupant on the monitor screen. May be. In addition, a parking space may be detected using information from the obstacle detection unit 3 such as an ultrasonic sonar or a radar, and a parking target position may be automatically set in the detected parking space. The parking target position may be automatically set by acquiring information from an infrastructure facility that provides information on a parking space that is present.

  The parking route calculation unit 2 calculates a parking route for guiding the vehicle to the parking target position set by the parking target position setting unit 1. FIG. 2A is a diagram illustrating an example of a parking route calculated by the parking route calculation unit 2 at the time of parallel parking (garage parking), and FIG. 2B is a diagram of the parking route calculation unit 2 at the time of parallel parking. It is a figure which shows an example of the calculated parking route. Note that PA in the figure is the parking target position set by the parking target position setting unit 1, V in the figure is the vehicle position where the parking operation starts, and PV in the figure is parked adjacent to the parking target position PA. Each parked vehicle is shown.

  When guiding the vehicle to the parking target position PA while backing the vehicle during parallel parking of the vehicle, the parking route calculation unit 2 calculates, for example, a curved route T0 shown in FIG. When the vehicle is parked in parallel, when the vehicle is guided to the parking target position PA while backing up, the parking route calculation unit 2 uses, for example, the curved route T1, the straight route T2, and the curved route T3 shown in FIG. A series of routes connected to each other is calculated as a parking route. Here, the curved route T0 shown in FIG. 2 (a) and the curved routes T1 and T3 shown in FIG. 2 (b) take the vehicle steering from the neutral state in consideration of the fact that the parking operation is performed by automatic steering. A clothoid curve that is a trajectory when moving while changing to a predetermined steering angle θx, a curve with a constant curvature that is a trajectory when moving while maintaining the steering of the vehicle at a predetermined steering angle θx, and a steering of the vehicle The path is a combination of a clothoid curve that is a trajectory when moving while returning to the neutral state from the angle θx. In other words, when performing a parking operation by automatic steering along the parking route, if a route that requires a stationary operation that changes the steering angle while the vehicle is stopped is calculated as the parking route, the actuator that drives the steering wheel Requesting excessive torque may cause a failure. Therefore, the parking route that does not require the stationary operation is calculated by obtaining the curved route T0 and the curved routes T1 and T2 as a combination of a clothoid curve and a curve having a constant curvature.

  The obstacle detection unit 3 detects an obstacle such as a parked vehicle existing in the vicinity of the parking target position. As the obstacle detection unit 3, an ultrasonic sonar, a radar, or the like is used as described above. For example, while the vehicle moves to the side where the parking operation starts after passing the side of the parking target position, An obstacle existing in the vicinity of the parking target position is detected, and the position information is output.

  When the parking route is calculated by the parking route calculation unit 2, the contact determination unit 4 determines whether or not there is a possibility of contact with an obstacle when the vehicle moves along the parking route. In particular, as will be described in detail later, the contact determination unit 4 applies at least a part of the parking route calculated by the parking route calculation unit 2, for example, the curved route T0 shown in FIG. 2A or FIG. 2B. Approximate the curved paths T1 and T2 shown by arcs, and easily determine the possibility of contact with the obstacles based on whether the obtained arc trajectory interferes with the obstacles detected by the obstacle detection unit 3 or not. The determination result is fed back to the parking route calculation unit 2. When the contact determination unit 4 determines that there is a possibility of contact with the obstacle, the parking route calculation unit 2 calculates a new parking route that avoids the obstacle. The specific method for calculating a new parking route will be described later in detail.

  The steering control unit 5 automatically controls the steering of the vehicle so that the vehicle moves along the parking route calculated by the parking route calculation unit 2. Specifically, the steering control unit 5 calculates an optimum steering amount for causing the vehicle position to follow the parking route while constantly monitoring the steering angle of the vehicle, and outputs the calculated steering amount to an actuator that drives the steering. In the case where the vehicle includes an electric power steering device, the steering control unit 5 may perform steering control of the vehicle using the electric power steering device.

[Specific method of arc approximation]
Next, a specific method for approximating at least a part of the parking route with an arc by the contact determination unit 4 will be described.

  The contact determination unit 4 is a clothoid included in the parking route calculated by the route calculation unit 2, such as the curved route T0 shown in FIG. 2A and the curved routes T1 and T2 shown in FIG. A path of a combination of a curve and a curve with a constant curvature (a combination of a path with a constant steering angle and a path with a change in steering angle) is set as a target path for arc approximation. In the following, the case where the curved path T0 shown in FIG. 2A is approximated by an arc will be described as an example. However, the curved path T1 and the curved path T2 shown in FIG. This method can be approximated by a circular arc.

  FIG. 3 is an enlarged view of the curved path T0 shown in FIG. In this curved path T0, the path from the path starting point A to the point P is a path from the clothoid curve, the path from the point P to the point Q, when the vehicle moves while changing the steering from the neutral state to the predetermined steering angle θx. However, the curve from the point Q to the route end point B returns the vehicle steering from the predetermined steering angle θx to the neutral state. It is a clothoid curve which is a locus when moving while moving. In addition, the dashed-dotted line in the figure has shown the circular arc which draws the curve from the point P to the point Q. The curve route T0 as described above is calculated by sequentially obtaining each position from the route start point A to the route end point B by repeated calculation.

  When this curved path T0 is approximated by an arc, first, an intermediate point between the path start point A and the path end point B is obtained as a path midpoint M as shown in FIG. For example, the midpoint M of the path can be easily obtained by storing a point of the number of repetitions that is half of the total number of repetitions in the iterative calculation when calculating the curved path T0.

  Next, a perpendicular bisector L2 of the line segment L1 connecting the route start point A and the route end point B is obtained. The perpendicular bisector L2 is a straight line passing through the route midpoint M. On the vertical bisector L2, a point C satisfying CA = CM (= CB) is obtained. Here, two points satisfying the above condition are obtained, and a point located inside the curved path T0 is set as a point C. When a circle with a radius R (= CA = CM = CB) is drawn around the point C, an arc CA (an arc indicated by a broken line in the drawing) approximating the curved path T0 can be obtained.

  The contact determination unit 4 contacts the obstacle when the vehicle passes the curved path T0 depending on whether the trajectory of the arc CA obtained as described above interferes with the obstacle detected by the obstacle detection unit 3. Determine if there is a possibility. Specifically, when an obstacle existing in the vicinity of the parking target position is detected by the obstacle detection unit 3, the contact determination unit 4 detects an arc CA that approximates the curved path T0 based on the position information. The maximum distance from the center point C to the obstacle is obtained. Note that the maximum distance from the center point C of the arc CA to the obstacle is, as shown in FIG. 5, in the obstacle (parked vehicle PV) that is located farthest from the center point C of the arc CA toward the arc CA. The distance CN between the portion N and the center point P of the arc CA can be obtained by recognizing the position of the obstacle (parked vehicle PV) and the position of the arc CA on the same two-dimensional coordinates. Then, when the maximum distance CN from the center point C of the arc CA to the obstacle is larger than the radius R of the arc CA, the contact determination unit 4 detects the obstacle (parked vehicle) when the vehicle passes the curved path T0. It is determined that there is a possibility of contact with PV).

  As described above, the contact determination unit 4 approximates a path of a combination of a clothoid curve and a curve with a constant curvature like a curved path T0 with an arc, and based on the obtained arc trajectory, the vehicle is in a parking operation. The possibility of contact with an obstacle is easily determined. However, if there is a part where the approximated arc trajectory is far away from the target path of the approximate arc, the determination accuracy of the possibility of contact decreases and is reliable. Sexuality will be impaired. Therefore, when the maximum separation distance between the approximated arc trajectory and the target path of the circular arc approximation exceeds the reference value, the target path of the circular arc approximation is divided into two or more path sections, and each path section is divided. It is desirable to approximate each with an arc.

The maximum separation distance between the approximated arc trajectory and the arc approximate target path is the maximum value Max (d) of the error d between the arc approximated target path and the arc trajectory approximating the target path. For example, as shown in FIG. 6, at an arbitrary point D on the curved path T0, which is the target path for circular approximation, the error d from the locus of the circular arc CA approximating the curved path T0 is obtained by the following equation (1). It is done.
d = | CD-R | (1)

  The error d is calculated on the curve path T0, and the maximum value Max (d) is obtained. Then, a predetermined threshold value (reference value) d1 is set for the maximum value Max (d) of the error d based on the required determination accuracy of the contact determination, and the maximum value Max (d) of the error d sets the threshold value d1. In the case of exceeding, the curved path T0 which is the target path of the circular arc approximation is divided into, for example, two path sections, and each path section is approximated by a circular arc, thereby reducing the error d. Here, the maximum value Max (d) of the error d is defined by the path start point A of the curved path T0, which is the target path of the circular arc approximation, the center point C of the circular arc CA, and the path end point B of the curved path T0. There is a correlation with the angle θ, and as shown in FIG. 7, the value of Max (d) increases as the angle θ increases. Therefore, an angle θ1 corresponding to the threshold value d1 is obtained in advance, and actually, the error d depends on whether or not the angle θ formed by the route start point A, the center point C of the arc CA, and the route end point B exceeds θ1. It is determined whether or not the maximum value Max (d) exceeds the threshold value d1, and if it exceeds, the curved path T0 is approximated by, for example, two arcs. It should be noted that the relationship as shown in FIG. 7 may be calculated in advance for each vehicle type and stored in a memory inside the ECU.

  FIG. 8 is a diagram illustrating an example of a case where a curved path T0, which is a target path for arc approximation, is approximated by two arcs. When approximating the curved path T0 with two arcs, first, the curved path T0 is divided into a path section T01 from the path start point A to the path middle point M and a path section T02 from the path middle point M to the path end point B. . Then, the midpoints M1 and M2 in the route sections T01 and T02 are obtained by the same method as that for the route midpoint M. Next, for the route segment T01, the distance from the route start point A, the route point T01 to the midpoint M1, and the route midpoint M on the vertical bisector of the line segment connecting the route start point A and the route midpoint M is as follows. A point C1 that is equal to each other is obtained, and a circle CA1 that approximates the route section T01 is obtained by drawing a circle with a radius R1 of a locus that passes through the route start point A, the middle point M1, and the route middle point M with the point C1 as the center. . For the route segment T02, the distances to the route midpoint M, the midpoint M2 of the route segment T02, and the route end point B are on the perpendicular bisector of the line segment connecting the route midpoint M and the route end point B, respectively. An equal point C2 is obtained, and a circle CA2 that approximates the route section T02 is obtained by drawing a circle with a radius R2 of a trajectory passing through the route middle point M, the middle point M2, and the route end point B with the point C2 as the center.

  If the maximum value Max (d) of the error d between the curve path T0 and the arc CA exceeds the threshold value d1 when the curve path T0 is approximated by one arc CA, the contact determination unit 4 as described above. The curved route T0 is divided into two route sections T01 and T02, and these are approximated by two arcs CA1 and CA2. And based on the locus | trajectory of circular arc CA1, CA2, the possibility of contact to the obstacle at the time of parking operation of a vehicle is determined. Thereby, since the error d between the curved path T0 and the arcs CA1 and CA2 can be reduced, the possibility of contact with the obstacle can be determined with higher accuracy.

[Change of parking route]
Next, a specific method for changing the parking route when the contact determination unit 4 determines that there is a possibility of contact with an obstacle will be described. In the following, the case where the parking route (curved route T0) at the time of parallel parking (garage parking) shown in FIG. 2A is changed to a new route that does not interfere with an obstacle will be described as an example. However, even when the parking route (curved route T1, T3) at the time of parallel parking shown in FIG. 2B is changed to a new route, the following method is applied to appropriately change the parking route. Can do.

  FIG. 9 exemplarily shows a case where the locus of the circular arc CA approximating the parking route at the time of parallel parking interferes with an obstacle (parked vehicle PV) existing in the vicinity of the parking target position detected by the obstacle detection unit 3. FIG. In the example shown in FIG. 9, since the distance CN from the center point C of the arc CA approximating the parking path to the corner N of the parked vehicle PV is larger than the radius R of the arc CA, the contact determination unit 4 Determines that there is a possibility of contacting the parked vehicle PV when moving along the parking path.

  In this case, for example, the parking path calculation unit 2 parks the original parking path from the path starting point A of the parking path along the vehicle posture (that is, on the trajectory when the steering is moved in a neutral state). A new parking route that avoids the parked vehicle PV is simply calculated by a method of shifting to a position that does not interfere with the PV. That is, the parking route calculation unit 2 obtains the center point C ′ (C′N <R) of the arc CA ′ obtained by shifting the arc CA that approximates the original parking route to a position that does not interfere with the parked vehicle PV. As a new parking route, a route that travels in the same curve as the original parking route after moving with the steering in the neutral state from the starting point A of the parking route to the distance from C to C ′ is neutral. calculate.

  Specifically, first, the degree of interference D1 (D1 = CN−R) between the locus of the arc CA approximating the original parking route and the parked vehicle PV is calculated.

Next, based on the degree of interference D1, a distance CC ′ between the center point C of the arc CA and the center point C ′ of the moved arc CA ′ is obtained. CC ′ can be obtained by the following equation (2), where ω1 [rad] is an angle surrounded by the corner N of the parked vehicle PV, the center point C of the arc CA, and the route end point B.
CC ′ = (D1 + α) / cos (ω1) (2)

  In the equation (2), α is a constant set in order to surely avoid interference with the parked vehicle PV, and is set to a constant value larger than zero.

  Then, a position where the steering is moved in a neutral state by a distance corresponding to CC ′ obtained as described above from the route start point A of the original parking route is set as a new route start point A ′, and this new route start point A ′. Therefore, a route that draws the same curve as the original parking route and moves is defined as a new parking route.

  By the way, since the new parking route calculated as described above is a route obtained by shifting the original parking route so as to avoid interference with the parked vehicle PV, the position of the route end point B ′ is the position of the original parking route. The position is shifted laterally with respect to the parking target position PA according to the degree of interference D1 with the parked vehicle PV. Here, if the degree of interference D1 with the parked vehicle PV is sufficiently small and the amount of deviation is small enough to fit within the parking space, there is no problem even if the vehicle is guided along the new parking route. If the amount of deviation increases to such an extent that it interferes with the adjacent parking space, there is a possibility that it will come into contact with another parked vehicle PV or the like parked in the adjacent parking space. Therefore, in such a case, as shown in FIG. 10, the parking route calculation unit 2 sets a turn-back position KA on the route of the new parking route, and turns the vehicle to the parking target position PA by turning back. To be able to guide properly.

  The cut-back position KA is obtained as follows, for example. That is, first, a trajectory RT of the outer rear wheel when the vehicle moves along a new parking route is obtained. The trajectory RT of the vehicle outer rear wheel is approximated by an arc whose center is the center point C ′ of the arc CA ′ approximating a new parking route and whose radius is a value obtained by adding the vehicle width VW to the radius R of the arc CA ′. it can. An intersection point K between the locus RT and the extension line PAL on the side surface of the parking target position PA is obtained, and the position of the intersection point K may be set as the position of the outer rear wheel of the vehicle at the turn-back position KA.

  However, since the turn-back position KA obtained as described above is in the middle of a new parking route, the vehicle steering is in a neutral state when the vehicle moves backward along the new parking route and reaches the turn-back position KA. is not. For this reason, if it tries to advance from this return position KA by automatic steering and return, it will move in the direction which approaches a parked vehicle PV, and is unpreferable. Therefore, it is desirable that the parking route calculation unit 2 corrects the route to the turn-back position K so that the steering is in a neutral state when the vehicle reaches the turn-back position KA.

  Here, the above-described new parking route is a route obtained by shifting the original parking route (curved route T0), and is a route in which the steering of the vehicle becomes neutral at the route end point B '. Then, as described above, the original parking route (curved route T0) is a route end point B in which a curve with a constant curvature (a route from point P to point Q in FIG. 3) and a clothoid curve are combined to become a steering neutral state. It is a route to reach. Therefore, the steering is in a neutral state when the vehicle reaches the turn-back position KA by adjusting the length of the curve with a constant curvature so that the path length of the new parking route becomes equal to the distance to the turn-back position KA. It can be corrected to the route.

The travel distance D2 from the route starting point A ′ of the new parking route to the turn-back position KA is determined by the route start point A ′, the center point C ′ of the arc CA ′, and the position K ′ of the inner rear wheel of the vehicle at the turn-back position KA. If the enclosed angle is ω2 [rad], it can be obtained by the following equation (3).
D2 = R × ω2 (3)

  Therefore, the vehicle at the turn-back position KA is adjusted by adjusting the length of the curve with a constant curvature included in the new parking route so that the route length of the new parking route becomes equal to D2 obtained as described above. It is possible to guide the vehicle so that the steering wheel is in a neutral state. Thereby, automatic steering including turning over becomes possible, and convenience can be improved.

  In the above example, the parking route calculation unit 2 automatically sets the return position KA on the new parking route. However, the return position KA may be set by an operation input by a vehicle occupant. . That is, an image representing the relationship between the new parking route and the parking target position PA is displayed on the monitor, and the vehicle occupant who refers to this monitor determines that switching is necessary and designates an arbitrary position on the new parking route. When the operation input for setting the return position is performed, the parking route calculation unit 2 corrects the new parking route so that the steering of the vehicle becomes neutral at the return position designated by the vehicle occupant. You may make it add.

  In the above example, it is assumed that the turnover is performed only once. However, a parking route including a plurality of turnovers may be calculated as a new parking route. In this case, it is possible to change the separation distance (constant α in the above equation (2)) from the obstacle (parked vehicle PV) serving as a reference when determining the trajectory of the new parking route according to the number of turnovers. desirable. That is, the constant α is set to a larger value at the first turn-over, and the value is decreased as the number of turn-backs increases. As a result, the vehicle can be guided so that it can be properly parked even in a narrow parking lot, and convenience can be improved.

[Example]
Next, specific examples of the present invention will be described.

  FIG. 11 is a block diagram showing a configuration of a parking assistance system 100 according to an embodiment of the present invention. The parking assist system 100 is a system that automatically controls not only the steering control of the vehicle but also the driving and braking to automatically guide the vehicle to the parking target position. Various types of parking route calculation and vehicle guidance are performed. The process is configured to be integratedly controlled by the parking assist ECU 110.

  The parking assist ECU 110 is an electric control unit mainly composed of a microcomputer having a CPU, a ROM, a RAM, an input / output circuit, a power circuit, and the like. The parking target position setting unit 1, the parking route calculation unit 2, the contact described above Each function of the determination unit 4 and the steering control unit 5 is realized by the parking assist ECU 110.

  The parking assist ECU 110 is connected to a brake ECU 120, a shift gear actuator 132 that drives the shift gear 132, an engine ECU 140, and a steering actuator 151 that drives the steering 152. A brake actuator 121 that drives the brake 122 is connected to the brake ECU 120.

  The parking assist ECU 110 receives signals from the wheel speed sensor 101 and the acceleration sensor 102 via the brake ECU 120. The parking assist ECU 110 also includes information on the external infrastructure 109 that provides information such as a signal from the shift sensor 103, an image from the in-vehicle camera 104, a signal from the sonar sensor (ultrasonic sonar) 108, an empty space in the parking lot, A signal from the rotary encoder 153 for detecting the steering amount is input. Further, the parking support ECU 110 is connected to a user interface such as an operation input device 105 for a vehicle occupant to input an operation, a monitor 106 for displaying various types of information, and a speaker 107 for outputting various types of information as audio.

  In the parking support system 100 configured as described above, the parking support ECU 110 includes various information such as an image taken by the in-vehicle camera 104, information from the sonar sensor 108 and the external infrastructure 109, and input information from the operation input device 105. One or more is used to set a parking available space around the vehicle as a parking target position, and a parking route for guiding the vehicle to the parking target position is calculated. Moreover, the parking assistance apparatus 110 recognizes the position of an obstacle such as a parked vehicle that exists in the vicinity of the parking target position by using information from the sonar sensor 108. Then, the parking assist ECU 110 approximates the calculated parking route with an arc by the above-described method, and may contact an obstacle when the vehicle moves along the parking route based on the obtained arc trajectory. If it is determined whether there is a possibility of contact with an obstacle, a new parking route that avoids the obstacle is calculated.

  In addition, the parking assist ECU 110 performs dead reckoning using sensor signals from the rotary encoder 153, the wheel speed sensor 101, the acceleration sensor 102, and the like, and estimates the position / posture of the vehicle moving along the parking route as needed. Then, based on the calculated parking route and the result of dead reckoning, and the sensor signal from the wheel speed sensor 101, the accelerator opening for moving the vehicle at the optimum speed along the parking route is commanded to the engine ECU 140. When the vehicle approaches the parking target position, a braking command is given to the brake ECU 120 to automatically perform braking control. Further, the parking assist ECU 110 performs optimum steering for moving the vehicle along the parking route based on the calculated parking route and the result of dead reckoning and the current steering amount of the steering 152 detected by the rotary encoder 153. The amount is calculated and the steering actuator 151 is controlled. In a vehicle equipped with a power steering device, steering control linked to the control of the power steering device may be performed.

  FIG. 12 is a flowchart showing an operation of parking support by the parking support system 100 configured as described above. The parking assistance operation flow shown in FIG. 12 is started when the vehicle occupant performs an input for instructing the start of parking assistance using the operation input device 105, and unless the instruction for canceling the parking assistance operation is input, Continue until the operation is complete.

  When an instruction input for starting parking assistance is made by a vehicle occupant, first, in step S1, a parking available space around the vehicle is detected and the position is set as a parking target position. If the parking space cannot be detected in step S1, the vehicle occupant is instructed to move the vehicle by displaying information on the monitor 106 or outputting sound from the speaker 107. When the setting of the parking target position is completed, in step S2, a parking route for guiding the vehicle to the parking target position set in step S1 is calculated. This parking route is calculated as a route combining a clothoid curve and a curve with a constant curvature in consideration of automatic steering control.

  Next, in step S3, the parking route calculated in step S2 is approximated by a circular arc by the method described above. Then, in step S4, it is determined whether or not there is a possibility of contact with an obstacle when the vehicle moves along the parking path calculated in step S2, based on the arc trajectory approximating the parking path. If it is determined that there is a possibility of contact with the obstacle, the process proceeds to the next step S5, and if it is determined that there is no possibility of contact with the obstacle, the process proceeds to step S8.

  In step S5, a new parking route that avoids the obstacle is calculated based on, for example, the method described above, based on the degree of interference between the arc locus approximating the parking route and the obstacle. In step S6, if it is determined that it is necessary to switch back based on the amount of deviation between the end point of the new parking route and the parking target position set in step S1, In step S7, a return position is set, and the new parking route calculated in step S5 is corrected so that the steering of the vehicle becomes neutral at the return position.

  Next, in step S8, the vehicle moves to the target position along the parking route calculated in step S2, the new parking route calculated in step S5, or the new parking route corrected in step S7. In addition, the vehicle is automatically controlled (path following control). In this route following control, the vehicle position and posture are always dead reckoned, and the result is fed back, and the parking route calculated in step S2, the new parking route calculated in step S5, or a new one corrected in step S7. The steering actuator 151 and the like are controlled so that the difference between the correct parking route and the actual moving route is minimized. Further, when the vehicle approaches the parking target position, a command for decreasing the accelerator opening is given to engine ECU 140 and a braking command is given to brake ECU 120 to stop the vehicle at the parking target position. When a turn-back position is set on the parking route, even when the vehicle approaches the turn-back position, a command to reduce the accelerator opening is given to the engine ECU 140 and a brake command is given to the brake ECU 120 to Stop. When the vehicle is stopped at the switch-back position, the shift gear actuator 131 is driven and controlled so that the gear position of the shift gear 132 is switched so that the traveling direction of the vehicle is reversed. Further, when the vehicle is stopped at the parking target position, the shift gear actuator 131 is driven and controlled to switch the gear position of the shift gear 132 to the parking range.

  The route follow-up control in step S8 is continued until it is determined in step S9 that the vehicle has reached the parking target position. Then, when it is determined in step S9 that the vehicle has reached the parking target position, in step S10, the vehicle occupant is informed that parking support has ended by displaying information on the monitor 106 and outputting sound from the speaker 107. A series of parking assistance operations are terminated.

  As described above in detail with reference to specific examples, the parking assist device to which the present invention is applied approximates at least a part of the parking route for guiding the vehicle to the parking target position with an arc. The possibility of contact with an obstacle during the parking operation of the vehicle is determined based on the trajectory. Therefore, according to this parking assistance apparatus, the possibility of contact with an obstacle during the parking operation of the vehicle can be determined very simply. In addition, when approximating at least a part of the parking route with an arc, the maximum separation distance between the path of the arc and the target route of the arc approximation when approximating the path to be approximated with an arc is a reference value. If the reference value is exceeded, it is possible to make contact with obstacles by dividing the target route for arc approximation into two or more multiple route sections and approximating each path section with an arc. Can be determined more accurately.

  In addition, according to the parking assistance device to which the present invention is applied, when it is determined that there is a possibility of contact with an obstacle during the parking operation of the vehicle, a new parking route that avoids the obstacle is calculated. Therefore, the vehicle can be guided to the parking target position while reliably avoiding contact with the obstacle. In addition, when the position of the end point of the new parking route deviates greatly from the parking target position, it is possible to reliably avoid contact with an obstacle by calculating a route to be turned back in the middle of the route as a new parking route. However, the vehicle can be accurately guided to the parking target position.

  In addition, when calculating a new parking route including turnover, the vehicle is returned to the parking target position in a manner that reflects the intention of the vehicle occupant by calculating the route for turning back at the position specified by the vehicle occupant. And can be guided appropriately. Furthermore, it is possible to calculate a route including a plurality of turnovers as a new parking route, and the distance from the obstacle as a reference when determining the trajectory of the new parking route according to the number of turnovers at that time. By changing, it becomes possible to guide the vehicle to the parking target position even in a narrow parking lot, and the convenience can be further improved.

  Moreover, according to the parking assistance apparatus to which the present invention is applied, the vehicle is guided to the parking target position by automatically controlling the steering of the vehicle so that the vehicle moves along the calculated parking route. Thus, the burden on the vehicle driver during the parking operation can be greatly reduced.

  The embodiment described above is an example of application of the present invention, and the technical scope of the present invention is not intended to be limited to the contents described in the above embodiment. That is, the technical scope of the present invention is not limited to the specific technical matters disclosed in the above embodiments, but includes various modifications, changes, alternative techniques, and the like that can be easily derived from this disclosure.

  For example, in the parking assist device described above, the obstacle detection unit 3 detects an obstacle such as a parked vehicle near the parking target position, and the obstacle detection unit 3 starts from the center point of the arc approximating the parking route. When the maximum distance to the detected obstacle is larger than the radius of the arc, it is determined that there is a possibility that the vehicle may come into contact with the obstacle during the parking operation, but there is an obstacle near the parking target position. If there is a trajectory of an arc that approximates the parking path is inflated by a predetermined amount or more in the lateral direction of the parking target position immediately before the parking target position, it is determined that there is a possibility of contact, etc. The possibility of contact with an obstacle during the parking operation of the vehicle may be determined based on the positional relationship between the trajectory of the circular arc approximating and the parking target position.

  In the above-described parking assistance device, the steering of the vehicle is automatically controlled so that the vehicle moves along the calculated parking route. However, the calculated parking route is recognized by a vehicle occupant by a monitor display or the like. Thus, the present invention can also be effectively applied to a configuration in which the steering along the parking route is left to the driving operation of the vehicle occupant.

It is a block diagram which shows the functional structure of the parking assistance apparatus to which this invention is applied. It is a figure which shows an example of the parking route calculated by the parking route calculation part, (a) is an example of the parking route at the time of parallel parking, (b) is a figure which shows an example of the parking route at the time of parallel parking. It is an enlarged view of the parking route (curved route T0) shown in FIG. It is a figure explaining the method of approximating the curve path | route T0 with a circular arc. It is a figure explaining the method of determining the contact possibility to an obstruction (parking vehicle PV) based on the locus | trajectory of circular arc CA which approximated the curved path | route T0. It is a figure explaining the method of calculating | requiring the error d of the curve path | route T0 and the locus | trajectory of the circular arc CA which approximates the said curve path | route T0. It is a figure which shows the relationship between the value of maximum value Max (d) of error d, and angle (theta) which the path | route start point A, the center point C of circular arc CA, and the path | route end point B make. It is a figure which shows the example at the time of approximating curve path | route T0 with two circular arcs. It is a figure explaining the method of changing a parking route, when it determines with possibility of contacting an obstruction. It is a figure explaining the method of setting the return position KA on the path | route of a new parking path | route. It is a block diagram which shows the structure of the parking assistance system which is one Example of this invention. It is a flowchart which shows the operation | movement of the parking assistance by the parking assistance system which is one Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Parking target position setting part 2 Parking route calculation part 3 Obstacle detection part 4 Contact determination part 5 Steering control part 100 Parking assistance system 108 Sonar sensor 110 Parking assistance ECU

Claims (11)

Parking target position setting means for setting the parking target position of the vehicle;
A parking route calculating means for calculating a parking route for guiding the vehicle to the parking target position;
Contact determination that approximates at least a part of the parking path with an arc and determines whether or not there is a possibility of contact with an obstacle when the vehicle moves along the parking path based on the obtained arc trajectory And a parking assist device. An obstacle detection means for detecting an obstacle near the parking target position;
The contact determination means determines that there is a possibility of contact with the obstacle when the maximum distance from the center point of the arc to the obstacle detected by the obstacle detection means is larger than the radius of the arc. The parking support apparatus according to claim 1, wherein   3. The contact determination unit according to claim 1, wherein a combination of a route with a constant steering rudder angle and a route with a change in steering rudder included in the parking route is a target route for arc approximation. Parking assistance device.   The contact determination means obtains an intermediate point between the route start point and the route end point of the target route as a route middle point, and sets a route start point, a route end point, and a point where distances to the route middle point are equal as a center point, a route start point, 4. The parking assist device according to claim 3, wherein an arc of a trajectory passing through a route end point and a route middle point is obtained as an arc that approximates the target route.   The contact determination means determines whether or not the maximum separation distance between the trajectory of the arc and the target path exceeds a reference value when the target path is approximated by a single arc. The parking assistance device according to claim 3, wherein the target route is divided into a plurality of route sections, and each route section is approximated by an arc.   The said parking route calculation means calculates the new parking route which avoids an obstacle, when it determines with the possibility of contacting an obstacle by the said contact determination means. The parking assistance device according to any one of the above.   The parking assistance device according to claim 6, wherein the parking route calculation unit calculates a route including a return as the new parking route.   The parking assist device according to claim 7, wherein the parking route calculation unit calculates a route for turning back at a position designated by a vehicle occupant as the new parking route.   The said parking route calculation means changes the separation distance from the said obstacle of the said new parking route according to the frequency | count of turning back, when calculating the said new parking route. Parking assistance device.   The steering control means for controlling the steering of the vehicle so as to move the vehicle along the parking route calculated by the parking route calculation means, further comprising a steering control means. Parking assistance device.   Approximate at least a part of the parking route calculated as a route for guiding the vehicle to the parking target position with an arc, and touch an obstacle when the vehicle moves along the parking route based on the obtained arc trajectory An obstacle contact determination method characterized by determining whether or not there is a possibility of failure.

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