Driving control method and driving control device

Abstract

A driving control device 100 acquires discrete travel route information including a plurality of reference points indicating the discrete positions on a travel route R, determines whether or not a curvature value of each interpolation section between the reference points is equal to or greater than a predetermined curvature threshold, interpolates an interpolation section, in which the curvature value is smaller than the curvature threshold, by spline interpolation based on an n-th degree polynomial function of a third degree or more, interpolates an interpolation section, in which the curvature value is equal to or greater than the curvature threshold, by spline interpolation based on an m-th degree polynomial function of a degree larger than that of the n-th degree polynomial function, generates continuous travel route information on the basis of the plurality of interpolation sections having been interpolated, and controls or assists the driving of an own vehicle 1 on the basis of the continuous travel route information.

Description

Operation control method and operation control device

[0001] The present invention relates to an operation control method and an operation control device.

[0002] The high precision map data utilization device described in Patent Document 1 interpolates discontinuous road shape data to make it continuous data based on road shape data included in high precision map data and a curve function that is a predetermined cubic function.

[0003] International Publication No. 2020 / 250368

[0004] However, in the method of interpolating road shape data described in Patent Document 1, route interpolation is performed based only on a predetermined cubic function, so in sections with curves, the curvature of the route after interpolation may change significantly, and it may not be possible to create a smooth driving route.

[0005] The problem to be solved by the present invention is to provide a driving control method and a driving control device that can control or assist driving of a vehicle based on a smooth driving route.

[0006] The present invention solves the above problem by determining, based on discrete driving route information, whether the curvature value of each interpolation section between multiple reference points of the driving route is greater than or equal to a predetermined curvature threshold, and if the curvature value is less than the curvature threshold, interpolating the interpolation section using spline interpolation based on an nth-order polynomial function of degree 3 or higher, and if the curvature value is greater than or equal to the curvature threshold, interpolating the interpolation section using spline interpolation based on an mth-order polynomial function of degree greater than the nth-order polynomial function.

[0007] According to the present invention, it is possible to control or assist the driving of a vehicle based on a smooth driving route.

[0008] 1 is a block diagram showing the configuration of a driving control device according to the present embodiment. FIG. 2 is a diagram schematically showing an example of a driving route interpolated by the driving control device shown in FIG. 1. FIG. 3 is a graph with curvature value on the vertical axis and route length on the horizontal axis, showing changes in curvature of a portion (interpolated sections X1 to X8) of the driving route shown in FIG. 2. FIG. 4 is a diagram schematically showing an example of an extension route interpolated by the driving control device shown in FIG. 1 when extending a driving route. FIG. 5 is a flowchart showing the steps of a driving control method executed by the driving control device shown in FIG. 1. FIG. 6 is a flowchart showing another example of the steps of a driving control method executed by the driving control device shown in FIG. 1.

[0009] An embodiment of the present invention will be described below with reference to the drawings. As shown in FIG. 1 , a host vehicle 1 includes a driving control device 100. The driving control device 100 controls or assists driving of the host vehicle 1 so that the host vehicle 1 travels along a predetermined driving route R. The driving control device 100 also generates a target trajectory (continuous driving route R) for controlling or assisting driving of the host vehicle 1. That is, the driving control device 100 also functions as a driving route generation device that generates the target trajectory (continuous driving route R). The driving control device 100 controls a drive mechanism 2, a brake mechanism 3, and a steering mechanism 4 of the host vehicle 1 based on the target trajectory. The drive mechanism 2 includes the operation of an internal combustion engine in an engine vehicle and the operation of a traction motor in an electric vehicle, and also includes torque distribution between the internal combustion engine and the traction motor in a hybrid vehicle. The brake mechanism 3 is a brake actuator. The steering mechanism 4 is a steering actuator. In this embodiment, the driving control device 100 may autonomously control the driving of the vehicle 1 or may execute control to assist the driver of the vehicle 1 in manual driving.

[0010] The vehicle 1 also has a map database 5, a vehicle position acquisition unit 6, and an input unit 7. The map database 5 is a memory configured to be accessible from the driving control device 100. The map database 5 stores three-dimensional high-precision map information including position information of various facilities and specific points. The vehicle position acquisition unit 6 detects radio waves transmitted from multiple satellite communications by a GPS unit and periodically acquires position information of the vehicle 1. The input unit 7 is a user interface that allows the occupant of the vehicle 1 to input information. For example, the occupant of the vehicle 1 inputs the destination of the vehicle 1 into the input unit 7.

[0011] The driving control device 100 includes a processor 10. The processor 10 includes a read-only memory (ROM) storing a program, a central processing unit (CPU) that executes the program stored in the ROM, and a random access memory (RAM) that functions as an accessible storage device. The processor 10 includes a driving plan setting unit 11, a discrete driving path acquisition unit 12, a curvature value determination unit 13, a driving path interpolation unit 14, a state quantity calculation unit 15, a continuous driving path generation unit 16, and a vehicle control unit 17. The processor 10 executes the functions of the driving plan setting unit 11, the discrete driving path acquisition unit 12, the curvature value determination unit 13, the driving path interpolation unit 14, the state quantity calculation unit 15, the continuous driving path generation unit 16, and the vehicle control unit 17 by using the CPU to execute the program stored in the ROM.

[0012] The driving plan setting unit 11 sets a driving plan including a driving route R based on the map information in the map database 5, the current position (starting point) of the vehicle 1 acquired by the vehicle position acquisition unit 6, and information such as a destination input by the occupant to the input unit 7. The driving route R may also be set by the occupant of the vehicle 1.

[0013] The discrete travel route acquisition unit 12 acquires discrete travel route information for the travel route R based on the travel plan set by the travel plan setting unit 11. The discrete travel route information is information including a plurality of reference points indicating discrete positions on the vehicle's travel route. As shown in FIG. 2 , the discrete travel route information includes status information for each of a plurality of reference points P1 to P14 on the travel route R. The status information is discrete information indicating the position coordinates of each of the reference points P0 to P14 in a predetermined coordinate system. The status information may also include discrete information indicating the vehicle speed, acceleration, azimuth angle, yaw rate value, etc. of the host vehicle 1 at each of the reference points P0 to P14, i.e., discrete time information. Each of the reference points P0 to P14 is a point at which the host vehicle 1 is predicted to pass at a predetermined time interval. The reference points P0 to P14 may be points set at predetermined intervals along the travel route R. For example, the discrete driving route acquisition unit 12 can acquire the discrete driving route information by using three-dimensional high-precision map information stored in a map database. The three-dimensional high-precision map information includes curvature data or azimuth data as data representing the degree of curvature of the road for each road section. Note that, although FIG. 2 shows a schematic representation of 15 reference points P0 to P14, the number of reference points is not limited to this.

[0014] Furthermore, the curvature value determination unit 13 shown in FIG. 1 determines whether the curvature value of each of the interpolated sections X1 to X14 between the reference points P0 to P14 is equal to or greater than a predetermined curvature threshold based on the discrete travel route information. For example, in the example shown in FIG. 2, the curvature values ​​of the interpolated sections X4 to X6 and X10 to X12, which form curved portions of the travel route R, are equal to or greater than the curvature threshold, while the curvature values ​​of the interpolated sections X1 to X3, X7 to X9, X13, and X14, which are substantially linear sections, are less than the curvature threshold. More specifically, the curvature value determination unit 13 determines whether the curvature value of each of the interpolated sections X1 to X14 is equal to or greater than a predetermined curvature threshold based on discrete curvature value information such as that shown by the dashed line L1 in FIG. 3. The curvature value determination unit 13 may use the curvature values ​​included in the curvature data of the above-mentioned three-dimensional high-precision map information. The curvature value determination unit 13 may also calculate the curvature value using spline interpolation based on a predetermined function, Bézier curve interpolation, or the like, for position information at a plurality of reference points P0 to P14, which indicate discrete positions. The dashed line L1 shown in FIG. 3 illustrates discrete information on the curvature value in the interpolated sections X1 to X8, which are part of the travel route R. The curvature value of each of the interpolated sections X1 to X14 is a curvature value estimated based on the state information of the reference points P0 to P14. In other words, the curvature value of each of the interpolated sections X1 to X14 is an estimated curvature value assuming that the curvature value is constant in each of the interpolated sections X1 to X14. The curvature threshold is a threshold value used to determine whether the travel route R is curved.

[0015] 1, the travel path interpolation unit 14 includes a parameter conversion unit 14a, a route parameter determination unit 14b, and a route parameter storage unit 14c. The travel path interpolation unit 14 interpolates each of the interpolation sections X1 to X14 by spline interpolation based on the determination result of the curvature value determination unit 13. Specifically, the travel path interpolation unit 14 interpolates the interpolation sections X1 to X3, X7 to X9, X13, and X14, whose curvature values ​​are less than the curvature threshold, by spline interpolation based on an n-th degree polynomial function of third degree or higher. The travel path interpolation unit 14 interpolates the interpolation sections X4 to X6 and X10 to X12, whose curvature values ​​are equal to or greater than the curvature threshold, by spline interpolation based on an m-th degree polynomial function of an order greater than the n-th degree polynomial function. Furthermore, the travel path interpolation unit 14 may interpolate all of the interpolation sections X1 to X14 by spline interpolation based on an nth-order polynomial function, and then determine whether the curvature value after interpolation of each interpolation section is equal to or greater than a curvature threshold, and may re-interpolate the interpolation sections X4 to X6 and X10 to X12 whose curvature value after interpolation is equal to or greater than the curvature threshold by spline interpolation based on an mth-order polynomial function. Note that in the following description, the nth-order polynomial function is assumed to be a cubic polynomial function, and the mth-order polynomial function is assumed to be a quartic polynomial function, but the orders of the nth-order polynomial function and the mth-order polynomial function are not limited to these.

[0016] The interpolation method of the travel route R by the parameter conversion unit 14a, the route parameter determination unit 14b, and the route parameter storage unit 14c of the travel route interpolation unit 14 will be described in more detail below. The parameter conversion unit 14a converts the discrete travel route information of each interpolation section X1 to X14 into a predetermined format (x ｉ , y ｉ , s ｉ ) (i = 0 to N-1) into a predetermined format (x ｉ , y ｉ , s ｉ ) includes the position information of the reference points P0 to P14. The parameter conversion unit 14a converts the discrete travel route information of each of the interpolation sections X1 to X14 into a predetermined format (x ｉ , y ｉ , t ｉ ) (i=0 to N-1).ｉ , y ｉ , t ｉ ) includes position information and time information of the reference points P0 to P14. In the equations described in this embodiment, N=15. In the following description, the parameter in this embodiment is the path length (s ｉ )

[0017] Next, the route parameter determination unit 14b estimates coefficient parameters of a cubic polynomial function (nth-order polynomial function) or a quartic polynomial function (mth-order polynomial function) to be used for spline interpolation for each interpolation section based on the discrete travel route information in the format converted by the parameter conversion unit 14a. Specifically, the route parameter determination unit 14b estimates coefficient parameters of a cubic polynomial function (nth-order polynomial function) to be used for spline interpolation for interpolation sections X1 to X3, X7 to X9, X13, and X14, whose curvature values ​​are less than the curvature threshold value. Furthermore, the route parameter determination unit 14b estimates coefficient parameters of a quartic polynomial function (mth-order polynomial function) to be used for spline interpolation for interpolation sections X4 to X6 and X10 to X12, whose curvature values ​​are equal to or greater than the curvature threshold value. The route parameter determination unit 14b then interpolates the interpolation sections X1 to X14 based on the estimated coefficient parameters.

[0018] Specifically, when the polynomial function used for spline interpolation is a third-order polynomial function (n-th order polynomial function) that can be expressed by the following equations (1) and (2), the path parameter determination unit 14b determines the coefficient parameter a ｉ , b ｉ , c ｉ , d ｉ , A ｉ , B ｉ , C ｉ , D ｉ Calculate.

[0019] Furthermore, when the polynomial function used for spline interpolation is a fourth-order polynomial function (m-th order polynomial function) that can be expressed by the following equations (3) and (4), the path parameter determination unit 14b determines the coefficient parameter a ｉ , b ｉ , c ｉ, d ｉ , e ｉ , A ｉ , B ｉ , C ｉ , D ｉ , E ｉ Calculate.

[0020] Furthermore, the route parameter storage unit 14c stores the coefficient parameters estimated by the route parameter determination unit 14b.

[0021] 1 calculates a state quantity corresponding to each value of the parameter (path length s or time t). When the parameter is path length s, the state quantity includes one or both of the position coordinates and the curvature value of each point on the travel route R. When the parameter is time t, the state quantity includes the position coordinates and the curvature value of each point on the travel route R, and at least one of the vehicle speed, acceleration, azimuth angle, and yaw rate value of the host vehicle 1 traveling at each point.

[0022] Furthermore, the continuous travel route generation unit 16 generates continuous travel route information including the state quantities calculated by the state quantity calculation unit 15. That is, the continuous travel route generation unit 16 generates continuous travel route information for controlling or assisting driving of the host vehicle 1 based on the interpolation sections X1 to X14 interpolated by the travel route interpolation unit 14. For example, the curvature value included in the continuous travel route information generated by the continuous travel route generation unit 16 varies smoothly, as shown by the solid line L2 in FIG. 3 . The travel route R generated by the continuous travel route generation unit, i.e., the post-interpolation travel route R, is a route combining the interpolation sections X1 to X3, X7 to X9, X13, and X14 interpolated based on a cubic polynomial function (an n-th order polynomial function) with the interpolation sections X4 to X6 and X10 to X12 interpolated based on a quartic polynomial function (an m-th order polynomial function).

[0023] The continuous driving path generation unit 16 may also acquire function switch points where the polynomial function used for spline interpolation switches from a cubic polynomial function (an nth-order polynomial function) to a quartic polynomial function (an mth-order polynomial function) or from a quartic polynomial function (an mth-order polynomial function) to a cubic polynomial function (an nth-order polynomial function). In the example shown in FIG. 2, the function switch points are reference points P3, P6, P9, and P12.

[0024] The continuous travel path generation unit 16 then determines whether the curvature change value at the function switch point is equal to or greater than a predetermined curvature switch threshold. The curvature change value is the amount of change when the curvature value changes on either side of the function switch point. For example, a predetermined section including the function switch point may be set, and the amount of change in the curvature value in that section may be calculated. If the curvature change value at the function switch point is equal to or greater than the curvature switch threshold, the continuous travel path generation unit 16 sets a predetermined switch section including the function switch point. The switch section may be an interpolation section upstream of the function switch point or an interpolation section downstream of the function switch point. Furthermore, the switch section may include an interpolation section upstream of the function switch point and an interpolation section downstream of the function switch point. For example, in the example shown in FIG. 3 , the reference point P6 is the function switch point, and the curvature change value at the reference point P6 is equal to or greater than the curvature switch threshold. Therefore, the continuous travel path generation unit 16 sets a switch section including the reference point P6. In this case, the switching section may be the interpolation section X6 upstream of the function switching point (reference point P6), or may be the interpolation section X7 downstream of the function switching point (reference point P6). Furthermore, the switching section may be a section including the interpolation section X6 upstream of the function switching point (reference point P6) and the interpolation section X7 downstream of the function switching point (reference point P6).

[0025] Furthermore, the continuous travel path generation unit 16 calculates a first curvature value C of the switching section calculated based on a third-order polynomial function (an n-th-order polynomial function). ｎ and a second curvature value C of the switching section calculated based on a fourth-order polynomial function (an m-th-order polynomial function). ｍ and the new curvature value C of the switching section are mixed using the following equation (5), where α is a number greater than 0 and less than 1. The continuous travel route generation unit 16 then regenerates the continuous travel route information based on the new curvature value C.

[0026] The continuous travel path generating unit 16 may also regenerate the continuous travel path information based on the yaw rate change value at the function switch point. The yaw rate change value is the amount of change when the yaw rate value changes across the function switch point. For example, a predetermined section including the function switch point may be set, and the amount of change in the yaw rate value in that section may be calculated. In this case, the continuous travel path generating unit 16 first determines whether the yaw rate change value at the function switch point is equal to or greater than a predetermined yaw rate switch threshold. If the yaw rate value at the function switch point is equal to or greater than the yaw rate switch threshold, the continuous travel path generating unit 16 sets a switch section including the function switch point. The yaw rate value at the function switch point is the value of the yaw rate when the host vehicle 1 passes through the function switch point.

[0027] Then, the continuous travel path generating unit 16 calculates the first yaw rate value Y in the switching section calculated based on a third-order polynomial function (an n-th-order polynomial function). ｎ and a second yaw rate value Y in the switching section calculated based on a fourth-order polynomial function (an m-th-order polynomial function). ｍ and the new yaw rate value Y of the switching section are calculated by mixing them using the following equation (6), where α is a number greater than 0 and less than 1. Then, the continuous driving route generating unit 16 regenerates the continuous driving route information based on the new yaw rate value Y.

[0028] In the above formulas (5) and (6), when the polynomial function switches from a third-order polynomial function (an nth-order polynomial function) to a fourth-order polynomial function (an mth-order polynomial function) at the function switching point, the continuous travel path generating unit 16 may gradually increase the value of α toward the downstream side. That is, the continuous travel path generating unit 16 sets the value of α so that the value of α at a second point downstream of the first point is larger than the value of α at the first point. That is, the continuous travel path generating unit 16 sets the value of α so that the value of α at a second point downstream of the first point is larger than the value of α at the first point. ｎ The first curvature value C included in the new curvature value C at the second point downstream of the first point is larger than the proportion of the component ofｎ Alternatively, the continuous travel path generating unit 16 calculates the new curvature value C so that the proportion of the first yaw rate value Y ｎ The first yaw rate value Y included in the new yaw rate value Y at the second point downstream of the first point is larger than the proportion of the component of ｎ That is, the continuous travel path generating unit 16 calculates the new yaw rate value Y so that the proportion of the component of the new curvature value C or the second curvature value C included in the new yaw rate value Y becomes smaller toward the downstream side. ｍ or second yaw rate value Y ｍ The value of α is set so that the proportion of the component of gradually increases.

[0029] Furthermore, in the above formulas (5) and (6), when the polynomial function switches from a fourth-order polynomial function (m-th order polynomial function) to a third-order polynomial function (n-th order polynomial function) at the function switching point, the continuous travel path generating unit 16 may gradually decrease the value of α toward the downstream side. That is, the continuous travel path generating unit 16 sets the value of α so that the value of α at the second point downstream of the first point is smaller than the value of α at the first point. That is, the continuous travel path generating unit 16 sets the value of α so that the value of α at the second point downstream of the first point is smaller than the value of α at the first point. ｎ The first curvature value C included in the new curvature value C at the second point downstream of the first point is larger than the proportion of the component of ｎ Alternatively, the continuous travel path generating unit 16 calculates the new curvature value C so that the proportion of the first yaw rate value Y ｎ The first yaw rate value Y included in the new yaw rate value Y at the second point downstream of the first point is larger than the proportion of the component of ｎ That is, the continuous travel path generating unit 16 calculates the new yaw rate value Y so that the proportion of the first curvature value C included in the new curvature value C or the new yaw rate value Y becomes larger toward the downstream side. ｎ or first yaw rate value Y ｎ The value of α is set so that the proportion of the component of gradually increases.

[0030] 1 controls the operations of the drive mechanism 2, braking mechanism 3, and steering mechanism 4 of the host vehicle 1 based on the continuous driving route information generated by the continuous driving route generation unit 16. That is, the vehicle control unit 17 controls or assists the driving of the host vehicle 1 based on the continuous driving route information.

[0031] Next, the functions of each component of the driving control device 100 when extending the driving route R as shown in FIG. 4 will be described. First, when it becomes necessary to extend the driving route R due to a change in destination or the like, the driving plan setting unit 11 re-sets a driving plan including an extended route Re. Specifically, the driving plan setting unit 11 generates an extended route Re by connecting a new driving route R2 to the previous driving route R1 (driving route R in FIG. 2 ) before extension. At this time, the driving plan setting unit 11 sets a boundary point Z between the previous driving route R1 and the new driving route R2. In the example shown in FIG. 4, the boundary point Z is a reference point P13. That is, the driving plan setting unit 11 sets the boundary point Z upstream of the end point P14 of the previous driving route R1. In the example shown in FIG. 4, the new driving route R2 has 12 reference points Q0 to Q11. Also, in the example shown in FIG. 4, M=12.

[0032] Next, the discrete travel route acquisition unit 12 acquires discrete travel route information of the new travel route R2 based on the travel plan reset by the travel plan setting unit 11. Then, the curvature value determination unit 13 determines whether the curvature value of each of the new interpolated sections X14 to X24 between the reference points Q0 to Q11 is equal to or greater than a predetermined curvature threshold, based on the discrete travel route information of the new travel route R2. For example, in the example shown in FIG. 4 , the curvature value of the new interpolated sections X17 to X19, which form curved portions of the new travel route R2, is equal to or greater than the curvature threshold, while the curvature values ​​of the new interpolated sections X14 to X16 and X20 to X24, which are substantially linear sections, are less than the curvature threshold.

[0033] The travel path interpolation unit 14 then interpolates each of the new interpolation sections X14 to X24 by spline interpolation based on the determination result of the curvature value determination unit 13. Specifically, the travel path interpolation unit 14 interpolates the new interpolation sections X14 to X16 and X20 to X24, whose curvature values ​​are less than the curvature threshold, by spline interpolation based on a third-order polynomial function (an nth-order polynomial function). The travel path interpolation unit 14 interpolates the new interpolation sections X17 to X19, whose curvature values ​​are equal to or greater than the curvature threshold, by spline interpolation based on a fourth-order polynomial function (an mth-order polynomial function).

[0034] At this time, the travel route interpolation unit 14 sets a predetermined connection condition for connecting the new travel route R2 with the previous travel route R1 at the boundary point Z. The travel route interpolation unit 14 sets the above connection condition using coefficient parameters stored in the route parameter storage unit 14c.

[0035] Specifically, when the curvature value of a new interpolation section (new interpolation section X14 in the example shown in FIG. 4) that connects to the boundary point Z on the new travel route R2 is less than the curvature threshold, the travel route interpolation unit 14 interpolates the new interpolation section X14 by spline interpolation based on a cubic polynomial function (n-th order polynomial function). The connection condition at this time is the cubic polynomial function f ｉ and a third-order polynomial function f relating to the new travel route R2 ｊ The above is to satisfy the following formulas (7) and (8).

[0036] In addition, when the curvature value of a new interpolation section (new interpolation section X14 in the example shown in FIG. 4) that connects to the boundary point Z on the new travel route R2 is equal to or greater than the curvature threshold, the travel route interpolation unit 14 interpolates the new interpolation section X14 by spline interpolation based on a fourth-order polynomial function (m-th order polynomial function). The connection condition at this time is the fourth-order polynomial function f ｉ and a fourth-order polynomial function f relating to the new travel route R2 ｊ The following equations (9) and (10) must be satisfied.

[0037] That is, the driving route interpolation unit 14 makes the previous driving route R1 and the new driving route R2 continuous by interpolating each of the new interpolation sections X14 to X24 of the new driving route R2 using spline interpolation so that the extended route Re satisfies the above-mentioned connection conditions at the boundary point Z.

[0038] Next, the procedure of the driving control method executed by the processor 10 of the driving control device 100 will be described using the flowchart shown in Figure 5. First, in step S1, the discrete driving route acquisition unit 12 acquires discrete driving route information of the driving route R based on the driving plan set by the driving plan setting unit 11.

[0039] Next, in step S2, the curvature value determination unit 13 determines whether the curvature value of each of the interpolation sections X1 to X14 is equal to or greater than the curvature threshold. If the curvature value of the interpolation section is less than the curvature threshold, in step S3, the travel path interpolation unit 14 interpolates the interpolation section based on a third-order polynomial function (an nth-order polynomial function). On the other hand, if the curvature value of the interpolation section is equal to or greater than the curvature threshold, in step S4, the travel path interpolation unit 14 interpolates the interpolation section based on a fourth-order polynomial function (an mth-order polynomial function).

[0040] Next, in step S5, the state quantity calculation unit 15 calculates the state quantities of each point on the interpolated travel route R. Then, in step S6, the continuous travel route generation unit 16 generates continuous travel route information including the state quantities calculated by the state quantity calculation unit 15.

[0041] Furthermore, in step S7, the continuous travel path generating unit 16 determines whether the curvature change value at the function switching point is equal to or greater than a curvature switching threshold. Note that in step S7, the continuous travel path generating unit 16 may determine whether the yaw rate change value at the function switching point is equal to or greater than a yaw rate switching threshold.

[0042] If it is determined in step S7 that "the curvature change value at the function switching point is less than the curvature switching threshold" or "the yaw rate change value at the function switching point is less than the yaw rate switching threshold", the process proceeds to step S9.

[0043] On the other hand, if it is determined in step S7 that "the curvature change value at the function switching point is equal to or greater than the curvature switching threshold value," then in step S8, the continuous travel path generating unit 16 calculates a first curvature value C based on a third-order polynomial function (n-th order polynomial function). ｎ and a second curvature value C based on a fourth-order polynomial function (m-th order polynomial function) ｍ Then, the continuous travel path generating unit 16 regenerates the continuous travel path information based on the new curvature value C. Furthermore, if it is determined in step S7 that "the yaw rate value at the function switching point is equal to or greater than the yaw rate switching threshold value," the continuous travel path generating unit 16 regenerates the continuous travel path information based on the first yaw rate value Y ｎ and a second yaw rate value Y based on a fourth-order polynomial function (m-th order polynomial function) ｍ The continuous travel route generating unit 16 then mixes the new yaw rate value Y to calculate a new yaw rate value Y for the switching section. The continuous travel route generating unit 16 then regenerates the continuous travel route information based on the new yaw rate value Y.

[0044] Then, in step S9, the driving control device 100 controls or assists the driving of the vehicle 1 based on the continuous driving route information.

[0045] 6, the driving control device 100 may omit steps S7 and S8 and execute step S9 after step S6. That is, the driving control device 100 controls or assists the driving of the vehicle 1 based on a travel route that combines an interpolated section interpolated based on a cubic polynomial function (an nth-order polynomial function) and an interpolated section interpolated based on a quartic polynomial function (an mth-order polynomial function).

[0046] As described above, the driving control device 100 according to this embodiment determines whether the curvature value of each of the interpolated sections X1 to X14 between the reference points P0 to P14 is equal to or greater than a predetermined curvature threshold, based on the discrete driving route information of the driving route R. The driving control device 100 then interpolates the interpolated sections whose curvature values ​​are less than the curvature threshold using spline interpolation based on an nth-order polynomial function of third or higher order, and interpolates the interpolated sections whose curvature values ​​are equal to or greater than the curvature threshold using spline interpolation based on an mth-order polynomial function, which is a higher order than the nth-order polynomial function. The driving control device 100 generates continuous driving route information based on the interpolated multiple interpolated sections X1 to X14 and controls or assists driving of the vehicle 1 based on the continuous driving route information. As a result, the driving control device 100 interpolates each of the interpolated sections X1 to X14 using spline interpolation based on an nth-order polynomial function of third or higher order or an mth-order polynomial function, thereby generating a smooth target trajectory. In particular, the driving control device 100 interpolates the interpolation section where the curvature value is equal to or greater than the curvature threshold value using spline interpolation based on an m-th order polynomial function, which has a higher order than an n-th order polynomial function, thereby preventing excessive changes in the curvature value in the curved section. Therefore, the driving control device 100 can control or assist the driving of the vehicle based on a smooth driving route. Furthermore, the driving control device 100 can calculate the curvature value of a curve that requires high-order differentiation or a clothoid curve by interpolating the driving route R using polynomial functions of different orders.

[0047] Furthermore, the driving control device 100 interpolates all interpolated sections X1 to X14 of the driving route R using spline interpolation based on an nth-order polynomial function based on the discrete driving route information, and determines whether the curvature value after interpolation of each of the interpolated sections X1 to X14 is equal to or greater than the curvature threshold.The driving control device 100 then re-interpolates the interpolated sections whose curvature values ​​after interpolation are equal to or greater than the curvature threshold using spline interpolation based on an mth-order polynomial function.This allows the driving control device 100 to more clearly determine whether the curvature value of each of the interpolated sections X1 to X14 is equal to or greater than the curvature threshold based on the driving route R that was initially interpolated using an nth-order polynomial function.

[0048] The operation control device 100 also determines whether the curvature change value at the function switching point where the order of the polynomial function used for spline interpolation is switched is equal to or greater than a predetermined curvature switching threshold. If the curvature change value is equal to or greater than the curvature switching threshold, the operation control device 100 sets a predetermined switching section including the function switching point. The operation control device 100 calculates the first curvature value C of the switching section calculated based on the n-th degree polynomial function. ｎ and a second curvature value C of the switching section calculated based on an m-th degree polynomial function. ｍ and are mixed in a predetermined ratio to calculate a new curvature value C. The driving control device 100 then regenerates the continuous driving route information based on the new curvature value C. This allows the driving control device 100 to prevent the curvature value at the function switching point from changing too much. This allows the driving control device 100 to generate a smooth target trajectory.

[0049] The driving control device 100 also determines whether the yaw rate change value at the function switching point is equal to or greater than a predetermined yaw rate switching threshold. If the yaw rate change value is equal to or greater than the yaw rate switching threshold, the driving control device 100 sets a switching section. The driving control device 100 calculates the first yaw rate value Y in the switching section calculated based on the n-th degree polynomial function. ｎ and a second yaw rate value Y in the switching section calculated based on an m-th degree polynomial function. ｍ and are mixed in a predetermined ratio to calculate a new yaw rate value Y. The driving control device 100 then regenerates the continuous driving route information based on the new yaw rate value Y. This allows the driving control device 100 to prevent the yaw rate value from changing too much at the function switching point. This allows the driving control device 100 to generate a smooth target trajectory.

[0050] In addition, when the polynomial function used for spline interpolation at the function switching point is switched from an n-th order polynomial function to an m-th order polynomial function, the operation control device 100 determines whether the first curvature value C included in the new curvature value C at the first point is ｎ The first curvature value C included in the new curvature value C at the second point downstream of the first point is larger than the proportion of the component of ｎOn the other hand, when the polynomial function is switched from an m-th degree polynomial function to an n-th degree polynomial function at the function switching point, the first curvature value C included in the new curvature value C at the first point is calculated so that the proportion of the component of ｎ The first curvature value C included in the new curvature value C at the second point downstream of the first point is larger than the proportion of the component of ｎ In this way, when the polynomial function used for spline interpolation at the function switching point is switched from an n-th order polynomial function to an m-th order polynomial function, the operation control device 100 calculates the new curvature value C so that the proportion of the component of ｎ to the second curvature value C ｍ On the other hand, when the polynomial function used for spline interpolation at the function switching point switches from an m-th order polynomial function to an n-th order polynomial function, the driving control device 100 can generate continuous driving route information so that the curvature value of the switching section becomes the second curvature value C ｍ to the first curvature value C ｎ Continuous driving route information can be generated so that the route changes smoothly.

[0051] In addition, when the polynomial function used for spline interpolation at the function switching point is switched from an n-th order polynomial function to an m-th order polynomial function, the driving control device 100 determines whether the first yaw rate value Y included in the new yaw rate value Y at the first point is a value of m. ｎ The first yaw rate value Y included in the new yaw rate value Y at the second point downstream of the first point is larger than the proportion of the component of ｎ On the other hand, when the polynomial function is switched from an m-th degree polynomial function to an n-th degree polynomial function at the function switching point, the first yaw rate value Y included in the new yaw rate value Y at the first point is calculated so that the proportion of the first yaw rate value Y is smaller than the proportion of the second yaw rate value Y. ｎ The first yaw rate value Y included in the new yaw rate value Y at the second point downstream of the first point is larger than the proportion of the component of ｎ In this way, when the polynomial function used for spline interpolation at the function switching point is switched from an n-th order polynomial function to an m-th order polynomial function, the driving control device 100 calculates the new yaw rate value Y so that the proportion of the first yaw rate value Yｎ to the second yaw rate value Y ｍ On the other hand, when the polynomial function used for spline interpolation at the function switching point switches from the mth-order polynomial function to the nth-order polynomial function, the driving control device 100 generates continuous driving route information so that the yaw rate value in the switching section is the second yaw rate value Y ｍ to the first yaw rate value Y ｎ Continuous driving route information can be generated so that the route changes smoothly.

[0052] Furthermore, the nth-order polynomial function is a cubic polynomial function, and the mth-order polynomial function is a quartic polynomial function. As a result, the driving control device 100 uses a cubic polynomial function to interpolate the interpolation section where the curvature value is less than the curvature threshold, thereby suppressing changes in the curvature value in a substantially straight section and allowing the vehicle 1 to travel stably. On the other hand, the driving control device 100 uses a quartic polynomial function to interpolate the interpolation section where the curvature value is less than the curvature threshold, thereby enabling the driving control device 100 to generate a target trajectory such that the curvature value changes smoothly in curved sections.

[0053] Furthermore, the parameter of the nth-order polynomial function and the mth-order polynomial function is the route length or time. As a result, when the parameter is the route length, the driving control device 100 can calculate a state quantity including either or both of the position coordinates and the curvature value of each point on the driving route R. Furthermore, when the parameter is time, the driving control device 100 can calculate a state quantity including at least one of the vehicle speed, acceleration, azimuth angle, and yaw rate value of the host vehicle 1 traveling at each point on the driving route R, in addition to either or both of the position coordinates and the curvature value.

[0054] Furthermore, when extending the travel route R, the driving control device 100 generates an extended route Re by connecting a new travel route R2 to the previous travel route R1 before the extension and sets a boundary point Z between the previous travel route R1 and the new travel route R2. The driving control device 100 interpolates each of the new interpolated sections X14 to X24 between the multiple reference points Q0 to Q11 of the new travel route R2 using spline interpolation so that a predetermined connection condition for connecting the new travel route R2 to the previous travel route R1 at the boundary point Z is satisfied. As a result, when extending the travel route R, the driving control device 100 can determine coefficient parameters for interpolating the new travel route R2 without updating the coefficient parameters used when interpolating the previous travel route R1. Therefore, the driving control device 100 can generate continuous travel route information for the extended route Re with lower computational cost than if all interpolated sections X1 to X24 of the extended route Re were interpolated at once.

[0055] 100... Driving control device 1... Vehicle 10... Processor 12... Discrete driving route acquisition unit 13... Curvature value determination unit 14... Driving route interpolation unit 16... Continuous driving route generation unit 17... Vehicle control unit R... Driving route R1... Previous driving route R2... New driving route P1 to P14... Reference points X1 to X14... Interpolation section X14 to X24... New interpolation section Z... Boundary point

Claims

1. A driving control method that uses a processor to control or assist the driving of a vehicle so that the vehicle travels along a predetermined driving path, The aforementioned processor, Using map information stored in a map database, discrete route information including a plurality of reference points indicating discrete locations on the aforementioned route is obtained. Determine whether the curvature value of each interpolation interval between the aforementioned reference points is greater than or equal to a predetermined curvature threshold. The interpolation interval in which the curvature value is less than the curvature threshold is interpolated by spline interpolation based on a polynomial function of degree n or higher, The interpolation interval in which the curvature value is greater than or equal to the curvature threshold is interpolated by spline interpolation based on an m-degree polynomial function, which has a higher degree than the n-degree polynomial function. Continuous travel path information is generated based on the multiple interpolated intervals. A driving control method for controlling or assisting the driving of the vehicle based on the continuous driving path information.

2. The aforementioned processor, Based on the discrete travel path information, all interpolation intervals of the travel path are interpolated by spline interpolation based on the nth polynomial function. Determine whether the interpolated curvature value for each of the interpolation intervals is equal to or greater than the curvature threshold. The driving control method according to claim 1, wherein the interpolated interval in which the interpolated curvature value is equal to or greater than the curvature threshold is re-interpolated by spline interpolation based on the m-th polynomial function.

3. The aforementioned processor, The function switching point is obtained where the polynomial function used for spline interpolation switches from the nth-degree polynomial function to the mth-degree polynomial function, or from the mth-degree polynomial function to the nth-degree polynomial function. It is determined whether the curvature change value at the function switching point is greater than or equal to a predetermined curvature switching threshold. If the curvature change value is greater than or equal to the curvature switching threshold, a predetermined switching interval including the function switching point is set. The first curvature value of the switching interval calculated based on the n-th degree polynomial function and the second curvature value of the switching interval calculated based on the m-th degree polynomial function are mixed in a predetermined ratio to calculate a new curvature value of the switching interval. The driving control method according to claim 1 or 2, wherein the continuous driving path information is regenerated based on the new curvature value.

4. The aforementioned processor, The function switching point is obtained where the polynomial function used for spline interpolation switches from the nth-degree polynomial function to the mth-degree polynomial function, or from the mth-degree polynomial function to the nth-degree polynomial function. It is determined whether the yaw rate change value at the function switching point is equal to or greater than a predetermined yaw rate switching threshold. If the yaw rate change value is greater than or equal to the yaw rate switching threshold, a predetermined switching interval including the function switching point is set. The first yaw rate value in the switching interval calculated based on the n-th degree polynomial function and the second yaw rate value in the switching interval calculated based on the m-th degree polynomial function are mixed in a predetermined ratio to calculate a new yaw rate value in the switching interval. The driving control method according to claim 1 or 2, wherein the continuous driving path information is regenerated based on the new yaw rate value Y.

5. The aforementioned processor, If the polynomial function switches from the nth-degree polynomial function to the mth-degree polynomial function at the function switching point, the new curvature value is calculated such that the proportion of the component of the first curvature value included in the new curvature value at the second point downstream of the first point is smaller than the proportion of the component of the first curvature value included in the new curvature value at the first point. The operation control method according to claim 3, wherein, when the polynomial function switches from the m-th degree polynomial function to the n-th degree polynomial function at the function switching point, the new curvature value is calculated such that the proportion of the component of the first curvature value included in the new curvature value at the second point downstream of the first point is greater than the proportion of the component of the first curvature value included in the new curvature value at the first point.

6. The aforementioned processor, If the polynomial function switches from the nth-degree polynomial function to the mth-degree polynomial function at the function switching point, the new yaw rate value is calculated such that the proportion of the component of the first yaw rate value included in the new yaw rate value at the second point downstream of the first point is smaller than the proportion of the component of the first yaw rate value included in the new yaw rate value at the first point. The operation control method according to claim 4, wherein, when the polynomial function switches from the m-th degree polynomial function to the n-th degree polynomial function at the function switching point, the new yaw rate value is calculated such that the proportion of the component of the first yaw rate value included in the new yaw rate value at the second point downstream of the first point is greater than the proportion of the component of the first yaw rate value included in the new yaw rate value at the first point.

7. The aforementioned nth-degree polynomial function is a third-degree polynomial function, The operation control method according to any one of claims 1 to 6, wherein the m-th degree polynomial function is a quartic polynomial function.

8. The driving control method according to any one of claims 1 to 7, wherein the parameters of the n-th degree polynomial function and the m-th degree polynomial function are the path length or time.

9. The aforementioned processor, When extending the aforementioned travel route, the new travel route is connected to the previous travel route before the extension to generate the extended route. The boundary point between the previously traveled route and the new traveled route is set, The driving control method according to any one of claims 1 to 8, wherein each of the new interpolation sections between a plurality of reference points of the new driving path is interpolated by spline interpolation so that the new driving path satisfies predetermined connection conditions for connecting with the previous driving path at the boundary point.

10. A driving control device that controls or assists the driving of a vehicle so that the vehicle travels along a predetermined driving path, A discrete driving route acquisition unit that uses map information stored in a map database to acquire discrete driving route information including a plurality of reference points indicating discrete locations on the driving route, A curvature value determination unit that determines whether the curvature value of each interpolation interval between the aforementioned reference points is greater than or equal to a predetermined curvature threshold, A travel path interpolation unit interpolates the interpolation interval in which the curvature value is less than the curvature threshold by spline interpolation based on an n-th degree polynomial function of degree 3 or higher, and interpolates the interpolation interval in which the curvature value is equal to or greater than the curvature threshold by spline interpolation based on an m-th degree polynomial function with a degree greater than the n-th degree polynomial function. A continuous travel path generation unit that generates continuous travel path information based on a plurality of interpolated intervals, A driving control device comprising a vehicle control unit that controls or assists the driving of the vehicle based on the continuous driving path information.