JP6724820B2 - Running trajectory generator - Google Patents

Description

The present disclosure relates to a traveling trajectory generation device.

As a device for generating a traveling track of a moving body such as a vehicle, a device described in Patent Document 1 below has been proposed. The device described in Patent Document 1 below treats conditions that do not collide with obstacles on the road and surroundings and conditions that do not go outside the road boundary as risk potentials, and treats the movable range of the front wheel steering angle as an inequality constraint condition. The running trajectory is generated by modeling the optimal control problem.

JP, 2011-186878, A

In Patent Document 1, in solving an optimal control problem, an appropriate solution candidate is given, and a process of adding a correction to the solution candidate is repeated. After processing the iterative operation, the result is checked to determine whether the condition for ending the iterative operation is satisfied. Various conditions are used as the termination condition of the iterative calculation, for example, when the number of iterations reaches a predetermined number or when the amount of change due to the iterative calculation becomes smaller than a predetermined level. Therefore, depending on the risk potential parameter and the setting of the termination condition, it may take longer than expected to satisfy the termination condition. Therefore, the maximum calculation amount depends on the traveling scene, and the upper limit of the cycle for updating the traveling track cannot be clearly grasped.

An object of the present disclosure is to provide a traveling trajectory generation device that can keep the maximum calculation amount within a predetermined calculation amount without depending on the driving scene and parameters.

The present disclosure is a traveling trajectory generation device, and a reference trajectory generation unit (201) that generates a reference trajectory based on lane information in which the vehicle is traveling, and a state quantity that defines upper and lower limit constraints on the state quantity of the vehicle. A constraint information generation unit (202) that calculates constraint information and manipulated variable constraint information that defines upper and lower bound constraints on the manipulated variable of the host vehicle, a reference trajectory, and at least one of state quantity constraint information and manipulated variable constraint information. A trajectory generation unit (203) that generates a traveling trajectory of the host vehicle based on the vehicle. The trajectory generation unit generates a partially reflected trajectory in which the state quantity constraint information or the manipulated variable constraint information is reflected with the reference trajectory as a reference, and the partially reflected trajectory is not reflected in the partially reflected trajectory as a reference. The travel trajectory is generated by reflecting the amount constraint information or the operation amount constraint information.

In the present disclosure, a reference trajectory based on only lane information is generated without being restricted, and the constraint information is reflected one by one on the reference trajectory, so that the amount of calculation until the travel trajectory is generated can be suppressed to a predetermined value or less. it can.

In addition, the reference numerals in parentheses described in "Means for solving the problem" and "Claims" indicate a correspondence relationship with "Mode for carrying out the invention" described later, It does not mean that the “means for solving the problems” and the “claims” are limited to “modes for carrying out the invention” described below.

According to the present disclosure, it is possible to provide a traveling trajectory generation device capable of keeping the maximum calculation amount within a predetermined calculation amount or less without depending on the traveling scene and parameters.

FIG. 1 is a block configuration diagram for explaining a functional configuration of the traveling track generation device according to the present embodiment. FIG. 2 is a diagram for explaining the setting of the state quantity. FIG. 3 is a diagram for explaining the setting of the entry prohibition area. FIG. 4 is a diagram for explaining the upper and lower limit settings for the lateral position. FIG. 5 is a diagram for explaining setting of upper and lower limits for acceleration. FIG. 6 is a flowchart for explaining the processing flow of the traveling trajectory generation device. FIG. 7 is a diagram for explaining an example of travel trajectory generation. FIG. 8 is a diagram for explaining an example of travel trajectory generation. FIG. 9 is a diagram for explaining the processing of the tracking error.

The present embodiment will be described below with reference to the accompanying drawings. In order to facilitate understanding of the description, the same constituent elements in each drawing are denoted by the same reference numerals as much as possible, and redundant description will be omitted.

FIG. 1 is a block configuration diagram of a system including a traveling trajectory generation device 20 according to the present embodiment.

The vehicle-mounted camera 10 photographs the front of the vehicle. The vehicle-mounted camera 10 continuously captures landscape images including a road outside line, a lane boundary line, and a road center line on a track on which the vehicle travels. The vehicle-mounted camera 10 outputs the image data of the captured landscape image to the travel trajectory generation device 20.

The distance measuring sensor 11 is a sensor that measures the distance to the surface of an obstacle such as another vehicle, a pedestrian, or a bicycle on the track. The measurement is continuously performed while changing the distance measurement angle. The distance-measuring sensor 11 outputs the data in which the distance and the distance-measuring angle are paired as distance-measuring data to the traveling track generation device 20.

The vehicle speed sensor 12 detects the speed of the host vehicle and outputs it as vehicle speed data to the traveling track generation device 20. The yaw rate sensor 13 detects the yaw rate of the host vehicle and outputs it as yaw rate data to the running trajectory generation device 20.

The traveling track generation device 20 executes a calculation for generating a traveling track based on the image data, the distance measurement data, the vehicle speed data, and the yaw rate data, and outputs it to the control device 14. The control device 14 calculates a steering torque for following the output running trajectory, and outputs it to the electric power steering device 15 as a steering torque command. The electric power steering device 15 steers the front wheels based on the steering torque command.

The running trajectory generation device 20 and the control device 14 are configured as a computer including, as hardware components, an arithmetic unit such as a CPU, a storage unit such as a RAM or a ROM, and an interface unit for exchanging data.

Subsequently, functional components of the traveling track generation device 20 will be described. The traveling track generation device 20 includes a reference track generation unit 201, a constraint information generation unit 202, and a track generation unit 203 as functional components.

The reference trajectory generation unit 201 is a portion that generates a reference trajectory based on lane information in which the vehicle is traveling. The reference trajectory generation unit 201 generates, as a reference trajectory, a traveling trajectory when it is assumed that there is no road obstacle on the basis of the lane information in which the vehicle is traveling.

The reference trajectory generation unit 201 detects white lines such as a road outside line, a lane boundary line, and a road center line from the image data of the landscape image captured by the vehicle-mounted camera 10 by a method such as Hough transform. As shown in FIG. 2, the reference trajectory generation unit 201 generates an imaginary line located at the center of the left and right lane boundaries from the detected white line as the reference trajectory Tr. The reference trajectory generation unit 201 outputs the generated reference trajectory to the trajectory generation unit 203.

The constraint information generation unit 202 is a part that calculates state amount constraint information that defines upper and lower limit constraints for the state amount of the own vehicle and operation amount constraint information that defines upper and lower limit constraints for the operation amount of the own vehicle.

The constraint information generation unit 202 calculates the state quantity of the host vehicle. As shown in FIG. 2, as an example, the host vehicle position y and the host vehicle angle θ can be used as the state quantities of the host vehicle C. The host vehicle position y is defined as the lateral position of the host vehicle center with respect to the nearest point Np on the reference trajectory Tr. The host vehicle angle θ is defined as the orientation of the host vehicle C with respect to the tangent line of the reference trajectory Tr at the nearest point Np.

It should be noted that the changing speed vy of the vehicle position y can be used as the state quantity instead of the vehicle angle θ. The changing speed vy can be estimated by a method such as a difference approximation using the vehicle position y or an approximate differentiation filter.

The constraint information generation unit 202 calculates an operation amount that is an input for operating the own vehicle. As an example of the operation amount, the front wheel steering angle δ and the acceleration ay of the vehicle position y are used.

The constraint information generation unit 202 calculates state amount constraint information that defines upper and lower limit constraints for the vehicle position y that is the state amount of the vehicle. For example, as shown in FIG. 3, it is possible to avoid the intrusion prohibited area including the road obstacles 31 and 32 by the upper and lower limit constraints of the vehicle position y. In the example shown in FIG. 3, the prediction points are set at equal intervals on the reference trajectory Tr in front of the host vehicle C. As a data group in which the upper limit value and the lower limit value are set for each prediction point, (yl[1], yu[1]), (yl[2], yu[2]), (yl[3], yu [3]) is calculated as the state quantity constraint information.

A specific method of calculating state quantity constraint information will be described with reference to FIG. Although FIG. 4 illustrates the calculation of the state quantity constraint information that defines the upper limit value, the state quantity constraint information that defines the lower limit value can be calculated in the same manner.

As shown in FIG. 4(A), the measurement data of the distance measuring sensor 11 is a point group on the coordinates including the s axis that means the path along the reference trajectory and the y axis that corresponds to the vehicle position y. Convert to. More specifically, the point group on the coordinates is generated so as to avoid the road obstacles 31 and 32.

Then, as shown in FIG. 4B, the point cloud data is fitted to a curve having the path s as a parameter, and yu=fu(s). At this time, the data located outside the lane is not used, and a point is set on the lane detected by the vehicle-mounted camera 10.

Subsequently, as shown in FIG. 4C, the curve is offset by a half width or more of the vehicle to give a margin, and yu'=fu(s)-yd. In the curve obtained in this way, the upper limit value corresponds to each prediction point.

As the state quantity constraint information, the state quantity may be the vehicle angle θ or the changing speed vy of the vehicle position, and upper and lower limit constraints for them may be defined. In these cases, the constraints are not due to external factors such as road obstacles but to the motion state of the vehicle to be achieved, so the desired upper and lower limits are defined on the basis of the constraints.

The constraint information generation unit 202 calculates operation amount constraint information that defines upper and lower limit constraints for the front wheel steering angle δ that is the operation amount of the host vehicle and the acceleration ay of the host vehicle position y. In these cases as well, the constraints are not due to external factors such as road obstacles but to the motion state that the host vehicle wants to achieve, so the desired upper and lower limits are defined on the basis of these constraints.

As shown in FIG. 5, unlike the case of the state quantity, a data set that includes the current vehicle position and does not include the predicted point at the end is calculated. As a data group in which the upper limit value and the lower limit value of the operation amount in such a point sequence are set, (al[0], au[0]), (al[1], au[1]), (al [2], au[2]) is calculated as the manipulated variable constraint information.

The constraint information generation unit 202 outputs the state amount constraint information and the operation amount constraint information to the trajectory generation unit 203.

The trajectory generation unit 203 is a portion that generates a traveling trajectory of the host vehicle based on the reference trajectory and at least one of the state amount constraint information and the operation amount constraint information. Various variables and functions are set in preparation for the explanation of the processing contents of the trajectory generation unit 203.

Since the state quantity and the manipulated variable are different physical quantities depending on the constraints to be handled, generally, the state quantity is x[k]=[x1[k],x2[k]] ^T and the manipulated quantity is u[k]. However, x1[k]=y[k]. k is an index of the prediction point, where k=0 indicates the current vehicle position.

At this time, the relationship between x[k] and u[k] is expressed by the expression f01 by linearly approximating the nonlinear function as necessary.

A is a matrix and b is a vector. For example, when the state quantity is the vehicle position y and the vehicle angle θ and the operation quantity is the front wheel steering angle δ, the relationship of the expression f02 is established.

Subsequently, various variables are summarized as a vector having the vehicle position and the value of each prediction point as elements. The manipulated variable u[k] is represented by formula f03. The state quantity x[k] is represented by the expression f04. The first state quantity x ₁ [k] is represented by the expression f05. The second state quantity x ₂ [k] is represented by the expression f06. The manipulated variable lower limit value u _l [k] is represented by the expression f07. The operation amount upper limit value u _u [k] is represented by the expression f08. The state quantity lower limit value x _l [k] is represented by an expression f09. The state quantity upper limit value x _u [k] is represented by the expression f10.

Next, since there are innumerable traveling trajectories that satisfy the constraints, it is possible to uniquely determine them by setting an index of the traveling trajectories. In this embodiment, the function of the expression f11 generally called "quadratic form" is used as an index.

Here, Q is a parameter matrix for adjusting the action of bringing the generated trajectory closer to the reference trajectory, and R is a parameter for adjusting the steepness of the change of the generated trajectory. N is the total number of prediction points. When the expression f11 is modified, it can be expressed as the expression f12 using U.

However, H is the matrix represented by Formula f13 and F is the matrix represented by Formula f14.

Furthermore, X, X1=Y, and X2 can be expressed as in formulas f15, f16, and f17.

Subsequently, the processes of the reference trajectory generation unit 201 and the trajectory generation unit 203 will be described with reference to FIGS. 6, 7, and 8. In step S101, the reference trajectory generation unit 201 generates a traveling trajectory when there is no constraint as a reference trajectory. As shown in FIG. 7A, a running trajectory that minimizes the function used as an index when there is no constraint is generated as the reference trajectory Tr. The reference trajectory Tr is algebraically established as in equations f18, f19, and f20. The reference trajectory Tr is represented by Y ₀ ^* .

In step S102 following step S101, the trajectory generation unit 203 corrects the reference trajectory Tr to a partial reflection trajectory Tra that satisfies the lower limit constraint of the state quantity. As shown in FIG. 7B, the road obstacle 33 and the lane are the lower limit restrictions. The partially reflected trajectory for the first state quantity is obtained by the equation f21, and the partially reflected trajectory for the second state quantity is obtained by the equation f22. The correction vector λxl is a vector that determines the correction amount of the trajectory.

The problem of finding a correction vector to satisfy the constraint is called a linear complementarity problem, and a known method such as the Lemke method is known as a method of solving this problem. When obtaining a correction vector for one type of constraint, the amount of calculation is finite and is less than the default, so the maximum amount of calculation in step S102 is less than the default.

In step S103 following step S102, the trajectory generation unit 203 corrects the partially reflected trajectory Tra to the partially reflected trajectory Trb that satisfies the upper limit constraint of the state quantity. As shown in FIG. 7C, the road obstacle 34 and the lane are the upper limit restrictions. The partially reflected trajectory for the first state quantity is obtained by the equation f23, and the partially reflected trajectory for the second state quantity is obtained by the equation f24.

Similar to step S102, the amount of calculation for obtaining the correction vector is finite and less than the default, so the maximum amount of calculation in step S103 is also less than the default.

In step S104 following step S103, the trajectory generation unit 203 corrects the partially reflected trajectory Trb to the partially reflected trajectory Trc that satisfies the lower limit constraint of the operation amount. The partial reflection trajectory Trc shown in (A) of FIG. 8 is obtained by the expression f25.

Similar to steps S102 and S103, since the amount of calculation for obtaining the correction vector is finite and less than the default, the maximum amount of calculation in step S104 is also less than the default.

In step S105 following step S104, the trajectory generation unit 203 corrects the partially reflected trajectory Trc to be the partially reflected trajectory Trd that satisfies the upper limit constraint of the operation amount. The partial reflection trajectory Trd shown in (B) of FIG. 8 is obtained by the expression f26.

In step S106 following step S105, the trajectory generation unit 203 checks whether or not the partially reflected trajectory Trd obtained in the above steps satisfies all the constraints. As shown in (C) of FIG. 8, if all the constraints are satisfied, the traveling trajectory Tre is set, and the process proceeds to step S107. If all the constraints are not satisfied, the process proceeds to step S108.

In step S107, the trajectory generation unit 203 notifies the control device 14 of the completion of the generation of the traveling trajectory Tre and the traveling trajectory Tre, and ends the processing. In step S108, the trajectory generation unit 203 notifies the control device 14 that the generated traveling trajectory does not satisfy the constraint, and ends the process.

Subsequently, the processing of the control device 14 will be described with reference to FIG. 9. The control device 14 selects one of the predicted points forming the traveling track Trf and calculates the distance e between the center axis of the host vehicle and the selected point. The target front wheel steering angle δt is calculated by the expression f27 so as to reduce the tracking error with the distance e as the tracking error. Note that g is a compatible parameter.

Subsequently, the steering torque Tw is calculated based on the equation f28 using the actual front wheel steering angle δw and the target front wheel steering angle δt. Note that g _p , g _d , and g _i are compatible parameters.

As described above, the traveling trajectory generation device 20 according to the present embodiment includes the normative trajectory generation unit 201 that generates the normative trajectory based on the lane information in which the host vehicle C is traveling, and the upper and lower limit constraints on the state quantity of the host vehicle C. A constraint information generation unit 202 that calculates the operation amount constraint information that defines the state amount constraint information and the operation amount constraint information that defines the upper and lower limit constraints for the operation amount of the vehicle C, a reference trajectory, and at least one of the state amount constraint information and the operation amount constraint information. And a trajectory generation unit 203 that generates a traveling trajectory of the host vehicle C based on The trajectory generation unit 203 generates a partially reflected trajectory in which the state quantity constraint information or the operation amount constraint information is reflected with the reference trajectory as a reference, and the partially reflected trajectory is not reflected in the partially reflected trajectory as a reference. The traveling trajectory is generated by reflecting the state quantity constraint information or the operation quantity constraint information.

In the present embodiment, a reference trajectory based on only lane information is generated without being restricted, and the constraint information is reflected on the reference trajectory one by one, so that the amount of calculation until the travel trajectory is generated is suppressed to a predetermined value or less. You can

In addition, in the present embodiment, the trajectory generation unit 203 reflects the state quantity constraint information on the reference trajectory and generates a state quantity reflected trajectory (see (B), (C) of FIG. 7 and its description) as a partially reflected trajectory. , The operation amount constraint information is reflected on the state quantity reflecting trajectory to generate a traveling trajectory. By reflecting the state quantity constraint information, which is an external factor that cannot be controlled by the host vehicle, first, the manipulated variable can be controlled on the premise of the reflected state quantity reflecting trajectory.

Further, in the present embodiment, the constraint information generation unit 202 calculates the state quantity constraint information by defining upper and lower limit constraints on the lateral position of the center of the own vehicle C in the lane in which the own vehicle C is traveling.

Further, in the present embodiment, the constraint information generation unit 202 can also calculate the state quantity constraint information by defining upper and lower limit constraints on the angle formed by the direction in which the host vehicle C faces the reference trajectory.

Further, in the present embodiment, the constraint information generation unit 202 can also calculate the state quantity constraint information by defining upper and lower limit constraints on the speed at which the lateral position of the vehicle C changes.

Further, in the present embodiment, the constraint information generation unit 202 can also calculate the operation amount constraint information by defining upper and lower limit constraints on the front wheel steering angle of the host vehicle C.

Further, in the present embodiment, the constraint information generation unit 202 can also calculate the operation amount constraint information by defining upper and lower limit constraints on the acceleration at which the lateral position of the center of the own vehicle C changes.

The present embodiment has been described above with reference to specific examples. However, the present disclosure is not limited to these specific examples. Those obtained by those skilled in the art who appropriately change the design are also included in the scope of the present disclosure as long as they have the features of the present disclosure. The elements provided in each of the specific examples described above and the arrangement, conditions, shapes, and the like of the elements are not limited to those illustrated, but can be appropriately changed. The respective elements included in the above-described specific examples can be appropriately combined as long as there is no technical contradiction.

20: Running trajectory generation device 201: Reference trajectory generation unit 202: Constraint information generation unit 203: Trajectory generation unit

Claims (6)

A travel trajectory generator,
A reference trajectory generation unit (201) for generating a reference trajectory based on lane information in which the vehicle is traveling,
A constraint information generation unit (202) that calculates state quantity constraint information that defines upper and lower limit constraints on the state quantity of the own vehicle and operation amount constraint information that defines upper and lower limit constraints on the operation amount of the own vehicle,
A trajectory generation unit (203) that generates a traveling trajectory of the host vehicle based on the reference trajectory and at least one of the state amount constraint information and the operation amount constraint information;
The trajectory generation unit,
Based on the reference trajectory, generate a partially reflected trajectory reflecting either one of the state amount constraint information or the operation amount constraint information,
The reference to the part reflected orbital been made to generate the running track by reflecting the state quantity restriction information or the operation amount restriction information is not reflected in the part reflected track,
The traveling trajectory generation device , wherein the constraint information generation unit calculates the state quantity constraint information by defining upper and lower limit constraints on a lateral position of a lane in which the host vehicle travels at the center of the host vehicle . A travel trajectory generator,
A reference trajectory generation unit (201) for generating a reference trajectory based on lane information in which the vehicle is traveling,
A constraint information generation unit (202) that calculates state quantity constraint information that defines upper and lower limit constraints on the state quantity of the own vehicle and operation amount constraint information that defines upper and lower limit constraints on the operation amount of the own vehicle,
A trajectory generation unit (203) that generates a traveling trajectory of the host vehicle based on the reference trajectory and at least one of the state amount constraint information and the operation amount constraint information;
The trajectory generation unit,
Based on the reference trajectory, generate a partially reflected trajectory reflecting either one of the state amount constraint information or the operation amount constraint information,
The reference to the part reflected orbital been made to generate the running track by reflecting the state quantity restriction information or the operation amount restriction information is not reflected in the part reflected track,
The constraint information generation unit is a traveling trajectory generation device that calculates upper limit and lower limit constraints on an angle formed by the direction in which the host vehicle faces the reference trajectory and calculates the state quantity constraint information . A travel trajectory generator,
A reference trajectory generation unit (201) for generating a reference trajectory based on lane information in which the vehicle is traveling,
A constraint information generation unit (202) that calculates state quantity constraint information that defines upper and lower limit constraints on the state quantity of the own vehicle and operation amount constraint information that defines upper and lower limit constraints on the operation amount of the own vehicle,
A trajectory generation unit (203) that generates a traveling trajectory of the host vehicle based on the reference trajectory and at least one of the state amount constraint information and the operation amount constraint information;
The trajectory generation unit,
Based on the reference trajectory, generate a partially reflected trajectory reflecting either one of the state amount constraint information or the operation amount constraint information,
The reference to the part reflected orbital been made to generate the running track by reflecting the state quantity restriction information or the operation amount restriction information is not reflected in the part reflected track,
The traveling trajectory generation device , wherein the constraint information generation unit calculates upper limit and lower limit constraints on the speed at which the lateral position of the host vehicle changes to calculate the state quantity constraint information . The traveling trajectory generation device according to any one of claims 1 to 3 ,
The trajectory generation unit reflects the state quantity constraint information on the reference trajectory to generate a state quantity reflected trajectory as a partially reflected trajectory, and reflects the operation amount constraint information on the state quantity reflected trajectory to drive the running trajectory. A travel trajectory generation device for generating. The traveling trajectory generation device according to any one of claims 1 to 4 ,
The traveling trajectory generation device, wherein the constraint information generation unit defines upper and lower limit constraints on a front wheel steering angle of the host vehicle and calculates the operation amount constraint information. The traveling trajectory generation device according to any one of claims 1 to 4 ,
The traveling trajectory generation device, wherein the constraint information generation unit calculates upper limit and lower limit constraints on the acceleration at which the lateral position of the center of the vehicle changes and calculates the operation amount constraint information.

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