Speed control method, device and equipment and computer readable storage medium

Abstract

The invention provides a speed control method, device and equipment and a computer readable storage medium, and the method comprises the steps: obtaining a car following model under the condition that the safety distance between a car and a front car is satisfied, and the car following model comprises a motion equation describing a plurality of longitudinal tracks, the motion equation describes the relation between the displacement of the self-vehicle in the longitudinal track and the time; solving the car following model to obtain a solving result; and controlling the speed of the vehicle based on the solving result. Wherein the multiple sections of longitudinal tracks comprise a first section of longitudinal track, a second section of longitudinal track, a third section of longitudinal track and a fourth section of longitudinal track; the acceleration change rate of the first section of longitudinal track is equal to that of the third section of longitudinal track, and the acceleration of the second section of longitudinal track and the acceleration of the fourth section of longitudinal track are constant values. According to the invention, the controllability and stability of car following driving can be ensured.

Description

Technical Field

[0001] The present invention relates to the field of speed control, and in particular to a speed control method, device, equipment and computer-readable storage medium. Background Art

[0002] The progress of artificial intelligence technology has promoted the rapid implementation of autonomous driving and assisted driving. Intelligent driving technology must not only ensure the safety of the vehicle during driving, but also take into account comfort, and comfort is often closely related to speed control. The following function is an extremely important function in autonomous driving or assisted driving. At the same time, the quality of following is also an important indicator for evaluating the performance of autonomous driving or assisted driving. After the system obtains the control target and environmental perception information, the speed control of the following vehicle needs to complete a comfortable and safe transition. Some speed controls use quintic polynomials or quartic polynomials, but these control methods only constrain the starting and ending states of the following vehicle, and the intermediate states are relatively uncontrollable. Summary of the invention

[0003] The present invention application provides a speed control method, device, equipment and computer-readable storage medium to solve the technical problem of how to improve the controllability of a vehicle during following vehicle driving.

[0004] In order to solve the above technical problems, the first aspect of the present invention application provides a speed control method, comprising:

[0005] Under the condition that a safe distance between the ego vehicle and the preceding vehicle is satisfied, a vehicle following model is obtained, wherein the vehicle following model includes a motion equation describing multiple longitudinal trajectories, and the motion equation describes a relationship between a displacement of the ego vehicle in the longitudinal trajectory and time;

[0006] Solving the following vehicle model to obtain a solution result; and controlling the speed of the self-vehicle based on the solution result;

[0007] The multiple longitudinal trajectories include a first longitudinal trajectory, a second longitudinal trajectory, a third longitudinal trajectory and a fourth longitudinal trajectory; the acceleration change rate of the first longitudinal trajectory is equal to the acceleration change rate of the third longitudinal trajectory, and the acceleration of the second longitudinal trajectory and the acceleration of the fourth longitudinal trajectory are constant values.

[0008] The following vehicle model applied for in the present invention includes motion equations of multiple longitudinal trajectories, which describe the relationship between the displacement of the ego vehicle in the longitudinal trajectory and time. By designing the above-mentioned multiple longitudinal trajectories in the following vehicle model, that is, there are multiple control segment points in the following vehicle process, compared with the control scheme of the prior art using a quintic polynomial or a quartic polynomial, not only the starting and ending states are constrained, but also the ego vehicle state at each control segment point is constrained, thereby ensuring the controllability of the starting state, the ending state and the intermediate state during the ego vehicle following vehicle driving process; in addition, the multiple longitudinal trajectories include a first longitudinal trajectory, a second longitudinal trajectory, a third longitudinal trajectory and a fourth longitudinal trajectory, the acceleration change rate of the first longitudinal trajectory is equal to the acceleration change rate of the third longitudinal trajectory, and the acceleration of the second longitudinal trajectory and the acceleration of the fourth longitudinal trajectory are constant values, so that the speed change of the ego vehicle during the whole following vehicle driving process is relatively smooth, which optimizes the user experience while ensuring the stability of the following vehicle driving.

[0009] As a preferred solution of the first aspect, the motion equation of the first longitudinal trajectory is:

[0010] f1(t)=a0×t 3 +b0×t 2 +c0t+d0;

[0011] The motion equation of the second longitudinal trajectory is:

[0012] f2(t)=a1×t 2 +b1×t+c1;

[0013] The motion equation of the third longitudinal trajectory is:

[0014] f3(t)=a2×t 3 +b2×t 2 +c2×t+d2;

[0015] The motion equation of the fourth longitudinal trajectory is:

[0016] f4(t)=a3t+b3;

[0017] Among them, f1(t) is the displacement of the vehicle at the tth moment in the first longitudinal trajectory, f2(t) is the displacement of the vehicle at the tth moment in the second longitudinal trajectory, f3(t) is the displacement of the vehicle at the tth moment in the third longitudinal trajectory, f4(t) is the displacement of the vehicle at the tth moment in the fourth longitudinal trajectory, and a0, b0, c0, d0, a1, b1, c1, a2, b2, c2, d2, a3 and b3 are all parameters to be solved.

[0018] As a preferred solution of the first aspect, solving the vehicle following model to obtain a solution result includes:

[0019] Under the preset constraint conditions, solving the vehicle following model to obtain the solution result;

[0020] The preset constraint conditions include: the longitudinal displacement of the connection position of the first longitudinal trajectory and the second longitudinal trajectory is continuous, the longitudinal speed of the connection position of the first longitudinal trajectory and the second longitudinal trajectory is continuous, the longitudinal acceleration of the connection position of the first longitudinal trajectory and the second longitudinal trajectory is equal, the longitudinal displacement of the connection position of the second longitudinal trajectory and the third longitudinal trajectory is continuous, the longitudinal speed of the connection position of the second longitudinal trajectory and the third longitudinal trajectory is continuous, the longitudinal acceleration of the connection position of the second longitudinal trajectory and the third longitudinal trajectory is equal, the longitudinal speed at the end of the third longitudinal trajectory is the target speed, the longitudinal acceleration at the end of the third longitudinal trajectory is zero, the longitudinal displacement of the connection position of the third longitudinal trajectory and the fourth longitudinal trajectory is continuous, the longitudinal speed of the connection position of the third longitudinal trajectory and the fourth longitudinal trajectory is continuous, the longitudinal acceleration change rate of the first longitudinal trajectory and the second longitudinal trajectory is a constant, and the total planned trajectory time length of the first longitudinal trajectory, the second longitudinal trajectory, the third longitudinal trajectory and the fourth longitudinal trajectory is a preset value.

[0021] As a preferred solution of the first aspect, solving the vehicle following model to obtain a solution result includes:

[0022] The solution result of the vehicle following model is sampled within a preset sampling interval to obtain the multiple analytical solutions, and the multiple analytical solutions are determined as the solution result; wherein the sampling interval is [0, T].

[0023] As a preferred solution of the first aspect, solving the vehicle following model to obtain a solution result includes:

[0024] The solution result of the following vehicle model is sampled within a preset sampling interval to obtain the multiple analytical solutions, and the multiple analytical solutions are determined as the solution result; wherein the sampling interval is [0, T], and T represents the total planned trajectory time length of the first longitudinal trajectory, the second longitudinal trajectory, the third longitudinal trajectory and the fourth longitudinal trajectory.

[0025] As a preferred solution of the first aspect, the controlling the speed of the vehicle based on the solution result includes:

[0026] Calculating the cost of each analytical solution through a preset cost function, selecting the analytical solution with the minimum cost, and controlling the speed of the vehicle based on the analytical solution with the minimum cost;

[0027] The preset cost function includes:

[0028] f cost=w1×cost speed +w2×cost comfort +w3×cost collision +w4×cost centerAcc +

[0029] w5×cost follow ;

[0030] cost speed =|f4(T)'-V s2 |;

[0031] cost comfort =|f2(t a )"|;

[0032]

[0033] cost2=V t ×V t ×k;

[0034]

[0035] cost3=max(0,X t -X safet );

[0036] Among them, f cost is the cost function, cost speed Cost is the speed cost. comfort Cost of comfort collision is the collision cost, cost centerAcc is the centripetal acceleration cost, cost follow is the stable following cost, w1, w2, w3, w4 and w5 are the weights corresponding to the cost function, speed cost, comfort cost, collision cost, centripetal acceleration cost and stable following cost respectively, k represents the lane curvature of the vehicle, V t represents the longitudinal velocity of the vehicle at time t, X t represents the longitudinal displacement of the vehicle at time t, X tfront represents the longitudinal displacement of the leading vehicle at time t, f4(T)' represents the longitudinal velocity of the vehicle at the end of the fourth longitudinal trajectory, and f2(t a )” represents the longitudinal acceleration at the initial moment of the second longitudinal trajectory, V s is the second preset speed value, X safet It represents the safety distance at the tth moment, and cost1, cost2 and cost3 are intermediate variables.

[0037] As a preferred embodiment of the first aspect, the speed control method further comprises:

[0038] When the distance between the vehicle and the front vehicle is less than or equal to a preset distance, the target speed is the current speed of the front vehicle;

[0039] When the distance between the vehicle and the preceding vehicle is greater than the preset distance, the target speed is a first preset speed value.

[0040] As a preferred embodiment of the first aspect, the speed control method further comprises:

[0041] When the current speed of the vehicle is greater than the preset speed limit, or the current acceleration of the vehicle is greater than the preset acceleration limit, the target speed is subjected to a golden section to obtain an updated target speed.

[0042] The second aspect of the present invention provides a speed control device, which includes an acquisition module and a control module; wherein:

[0043] The acquisition module is used to acquire a vehicle following model under the condition that a safe distance between the vehicle and the preceding vehicle is satisfied, wherein the vehicle following model includes a motion equation describing multiple longitudinal trajectories, wherein the motion equation describes the relationship between the displacement of the vehicle in the longitudinal trajectory and time;

[0044] The control module is used to solve the following vehicle model to obtain a solution result; and control the speed of the vehicle based on the solution result;

[0045] The multiple longitudinal trajectories include a first longitudinal trajectory, a second longitudinal trajectory, a third longitudinal trajectory and a fourth longitudinal trajectory; the acceleration change rate of the first longitudinal trajectory is equal to the acceleration change rate of the third longitudinal trajectory, and the acceleration of the second longitudinal trajectory and the acceleration of the fourth longitudinal trajectory are constant values.

[0046] In some preferred embodiments of the second aspect, the motion equation of the first longitudinal trajectory is:

[0047] f1(t)=a0×t 3 +b0×t 2 +c0t+d0;

[0048] The motion equation of the second longitudinal trajectory is:

[0049] f2(t)=a1×t 2 +b1×t+c1;

[0050] The motion equation of the third longitudinal trajectory is:

[0051] f3(t)=a2×t 3 +b2×t 2+c2×t+d2;

[0052] The motion equation of the fourth longitudinal trajectory is:

[0053] f4(t)=a3t+b3;

[0054] Among them, f1(t) is the displacement of the vehicle at the tth moment in the first longitudinal trajectory, f2(t) is the displacement of the vehicle at the tth moment in the second longitudinal trajectory, f3(t) is the displacement of the vehicle at the tth moment in the third longitudinal trajectory, f4(t) is the displacement of the vehicle at the tth moment in the fourth longitudinal trajectory, and a0, b0, c0, d0, a1, b1, c1, a2, b2, c2, d2, a3 and b3 are all parameters to be solved.

[0055] In some preferred implementations of the second aspect, the control module solves the vehicle following model to obtain a solution result, including:

[0056] The control module solves the vehicle following model under the preset constraint conditions to obtain the solution result;

[0057] The preset constraint conditions include: the longitudinal displacement of the connection position of the first longitudinal trajectory and the second longitudinal trajectory is continuous, the longitudinal speed of the connection position of the first longitudinal trajectory and the second longitudinal trajectory is continuous, the longitudinal acceleration of the connection position of the first longitudinal trajectory and the second longitudinal trajectory is equal, the longitudinal displacement of the connection position of the second longitudinal trajectory and the third longitudinal trajectory is continuous, the longitudinal speed of the connection position of the second longitudinal trajectory and the third longitudinal trajectory is continuous, the longitudinal acceleration of the connection position of the second longitudinal trajectory and the third longitudinal trajectory is equal, the longitudinal speed at the end of the third longitudinal trajectory is the target speed, the longitudinal acceleration at the end of the third longitudinal trajectory is zero, the longitudinal displacement of the connection position of the third longitudinal trajectory and the fourth longitudinal trajectory is continuous, the longitudinal speed of the connection position of the third longitudinal trajectory and the fourth longitudinal trajectory is continuous, the longitudinal acceleration change rate of the first longitudinal trajectory and the second longitudinal trajectory is a constant, and the total planned trajectory time length of the first longitudinal trajectory, the second longitudinal trajectory, the third longitudinal trajectory and the fourth longitudinal trajectory is a preset value.

[0058] In some preferred implementations of the second aspect, the control module solves the vehicle following model to obtain a solution result, including:

[0059] The control module samples the solution results of the vehicle following model within a preset sampling interval to obtain the multiple analytical solutions, and determines the multiple analytical solutions as the solution results; wherein the sampling interval is [0, T], and T represents the total planned trajectory time length of the first longitudinal trajectory, the second longitudinal trajectory, the third longitudinal trajectory and the fourth longitudinal trajectory.

[0060] In some preferred implementations of the second aspect, the control module controls the speed of the vehicle based on the solution result, including:

[0061] The control module calculates the cost of each analytical solution through a preset cost function, selects the analytical solution with the minimum cost, and controls the speed of the vehicle based on the analytical solution with the minimum cost;

[0062] The preset cost function includes:

[0063] f cost =w1×cost speed +w2×cost comfort +w3×cost collision +w4×cost centerAcc +

[0064] w5×cost follow ;

[0065] cost speed =|f4(T)'-V s2 |;

[0066] cost comfort =|f2(t a )"|;

[0067]

[0068]

[0069] cost2=V t ×V t ×k;

[0070]

[0071] cost3=max(0,X t -X safet );

[0072] Among them, f cost is the cost function, cost speed Cost is the speed cost. comfort Cost of comfort collision is the collision cost, cost centerAcc is the centripetal acceleration cost, cost follow is the stable following cost, w1, w2, w3, w4 and w5 are the weights corresponding to the cost function, speed cost, comfort cost, collision cost, centripetal acceleration cost and stable following cost respectively, k represents the lane curvature of the vehicle, V trepresents the longitudinal velocity of the vehicle at time t, X t represents the longitudinal displacement of the vehicle at time t, X tfront represents the longitudinal displacement of the leading vehicle at time t, f4(T)' represents the longitudinal velocity of the vehicle at the end of the fourth longitudinal trajectory, and f2(t a )” represents the longitudinal acceleration at the initial moment of the second longitudinal trajectory, V s is the second preset speed value, X safet It represents the safety distance at the tth moment, and cost1, cost2 and cost3 are intermediate variables.

[0073] In some preferred embodiments of the second aspect, when the distance between the vehicle and the leading vehicle is less than or equal to a preset distance, the target speed is the current speed of the leading vehicle; when the distance between the vehicle and the leading vehicle is greater than the preset distance, the target speed is a first preset speed value.

[0074] In some preferred embodiments of the second aspect, the speed control device also includes an update module, which is used to perform golden section on the target speed to obtain an updated target speed when the current speed of the vehicle is greater than a preset speed limit or the current acceleration of the vehicle is greater than a preset acceleration limit.

[0075] A third aspect of the present application provides a terminal device, comprising a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein the processor implements the speed control method when executing the computer program.

[0076] The fourth aspect of the present application provides a computer-readable storage medium, which includes a stored computer program, wherein when the computer program is running, the device where the computer-readable storage medium is located is controlled to execute the speed control method. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] Figure 1 : A flow chart of the first embodiment of the speed planning method provided in the present application.

[0078] Figure 2 : A schematic diagram of a vehicle following scenario provided in the present invention application.

[0079] Figure 3 : A schematic diagram of a position curve of the first embodiment of the speed planning method provided in the present application.

[0080] Figure 4 : A schematic diagram of a speed curve of the first embodiment of the speed planning method provided in the present application.

[0081] Figure 5 : A schematic diagram of the acceleration curve of the first embodiment of the speed planning method provided in the present application.

[0082] Figure 6 : A schematic diagram of an acceleration curve of an acceleration scenario provided in the present invention application.

[0083] Figure 7 : A schematic diagram of an acceleration curve for a deceleration scenario provided in the present invention application.

[0084] Figure 8 : A schematic structural diagram of the first embodiment of the speed planning device provided in the present application. DETAILED DESCRIPTION

[0085] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0086] Embodiment 1

[0087] Please refer to Figure 1 , Figure 1 A speed control method provided by the present invention includes steps S101 to S102; wherein:

[0088] Step S101, under the condition of satisfying the safety distance between the ego vehicle and the preceding vehicle, a vehicle following model is obtained, wherein the vehicle following model includes a motion equation describing multiple longitudinal trajectories, and the motion equation describes the relationship between the displacement of the ego vehicle in the longitudinal trajectory and time.

[0089] In this embodiment, the calculation formula of the safety distance is as follows:

[0090] X safe =t safe× V0+X min_safe ; (1)

[0091] Among them, X safe is the safety distance, V0 is the speed of the vehicle, X min_safe Indicates the minimum following distance, t safe Represents the time parameter.

[0092] like Figure 2As shown, vehicle A is the vehicle itself, and vehicle B is the front vehicle. The vehicle itself needs to maintain a certain distance from the front vehicle, which is less than the safety distance. In some embodiments, the safety distance can be 100 meters, the time parameter can be 1 to 3 seconds, and the minimum distance can be 1 to 5 meters, which can be specifically set by the automobile developer or the driver.

[0093] In some following scenarios based on autonomous driving or assisted driving, the vehicle needs to use the following function to keep the distance between itself and the vehicle in front as close as possible to a safe distance. Since the speed and position of the vehicle in front are changing dynamically and may even stop suddenly, the speed needs to be controlled during the following process to ensure the safety and comfort of the user.

[0094] The multiple longitudinal trajectories of this embodiment include a first longitudinal trajectory, a second longitudinal trajectory, a third longitudinal trajectory and a fourth longitudinal trajectory. The acceleration change rate of the first longitudinal trajectory is equal to the acceleration change rate of the third longitudinal trajectory, and the acceleration of the second longitudinal trajectory and the acceleration of the fourth longitudinal trajectory are constant values.

[0095] This embodiment uses the above-mentioned multi-segment longitudinal trajectory, that is, there are multiple control segment points in the process of following the vehicle. Compared with the control scheme of the prior art using a quintic polynomial or a quartic polynomial, this not only constrains the starting and ending states, but also constrains the state of the ego vehicle at each control segment point, thereby ensuring the controllability of the starting state, the ending state and the intermediate state during the ego vehicle following the vehicle; in addition, the multi-segment longitudinal trajectory includes a first longitudinal trajectory, a second longitudinal trajectory, a third longitudinal trajectory and a fourth longitudinal trajectory, the acceleration change rate of the first longitudinal trajectory is equal to the acceleration change rate of the third longitudinal trajectory, the acceleration of the second longitudinal trajectory and the acceleration of the fourth longitudinal trajectory are constant values, so that the speed change of the ego vehicle during the whole process of following the vehicle is relatively smooth, which optimizes the user experience while ensuring the stability of following the vehicle.

[0096] like Figures 3 to 5 As shown, Figure 3 Schematic diagram of the position of the speed control method of this embodiment (the ordinate is the position or displacement), Figure 4 Schematic diagram of the speed control method of this embodiment (the vertical axis is speed), Figure 5 Schematic diagram of the speed control method shown in this embodiment (the vertical axis is acceleration), Figures 3 to 5 The horizontal axis is time. Figure 5 The first acceleration curve, the second acceleration curve, the third acceleration curve and the fourth acceleration curve correspond to the first longitudinal trajectory, the second longitudinal trajectory, the third longitudinal trajectory and the fourth longitudinal trajectory of this embodiment respectively.

[0097] In some preferred implementations, the following vehicle model specifically includes:

[0098] The motion equation of the first longitudinal trajectory is:

[0099] f1(t)=a0×t 3 +b0×t 2 +c0t+d0; (2)

[0100] The motion equation of the second longitudinal trajectory is:

[0101] f2(t)=a1×t 2 +b1×t+c1; (3)

[0102] The motion equation of the third longitudinal trajectory is:

[0103] f3(t)=a2×t 3 +b2×t 2 +c2×t+d2; (4)

[0104] The motion equation of the fourth longitudinal trajectory is:

[0105] f4(t)=a3t+b3;(5)

[0106] Among them, f1(t) is the displacement of the vehicle at the tth moment in the first longitudinal trajectory, f2(t) is the displacement of the vehicle at the tth moment in the second longitudinal trajectory, f3(t) is the displacement of the vehicle at the tth moment in the third longitudinal trajectory, f4(t) is the displacement of the vehicle at the tth moment in the fourth longitudinal trajectory, and a0, b0, c0, d0, a1, b1, c1, a2, b2, c2, d2, a3 and b3 are all parameters to be solved.

[0107] In step S102 of this embodiment, by obtaining the above-mentioned parameters to be solved and using them for speed control of the vehicle, it is possible to ensure that the speed of the vehicle is further smoothed during the process of following the vehicle in front, improve the refinement of speed control during the process of following the vehicle, and further optimize the user's driving experience.

[0108] Step S102, solving the following vehicle model to obtain a solution result; and controlling the speed of the vehicle based on the solution result.

[0109] In some embodiments, several constraints can be pre-set in the process of solving the vehicle following model to obtain more accurate results. Exemplarily, the preset constraints include: the longitudinal displacement of the connection position of the first longitudinal trajectory and the second longitudinal trajectory is continuous, the longitudinal speed of the connection position of the first longitudinal trajectory and the second longitudinal trajectory is continuous, the longitudinal acceleration of the connection position of the first longitudinal trajectory and the second longitudinal trajectory is equal, the longitudinal displacement of the connection position of the second longitudinal trajectory and the third longitudinal trajectory is continuous, the longitudinal speed of the connection position of the second longitudinal trajectory and the third longitudinal trajectory is continuous, the longitudinal acceleration of the connection position of the second longitudinal trajectory and the third longitudinal trajectory is equal, the longitudinal speed at the end of the third longitudinal trajectory is the target speed, the longitudinal acceleration at the end of the third longitudinal trajectory is zero, the longitudinal displacement of the connection position of the third longitudinal trajectory and the fourth longitudinal trajectory is continuous, the longitudinal speed of the connection position of the third longitudinal trajectory and the fourth longitudinal trajectory is continuous, the longitudinal acceleration change rate of the first longitudinal trajectory and the second longitudinal trajectory is a constant, and the total planning trajectory time length of the first longitudinal trajectory, the second longitudinal trajectory, the third longitudinal trajectory and the fourth longitudinal trajectory is a preset value.

[0110] Combining the above content and formulas (2) to (5), it can be specifically expressed by the formula:

[0111] f1(0)=0;(6)

[0112] f1(0)'=V0;(7)

[0113] f1(0)”=0;(8)

[0114] f1(t a )=f2(t a );(9)

[0115] f1(t a )'=f2(t a )';(10)

[0116] f1(t a )”=f2(t a )”; (11)

[0117] f2(t a +t b )=f3(t a +t b ); (12)

[0118] f2(t a +t b )'=f3(t a +t b )';(13)

[0119] f2(ta +t b )”=f3(t a +t b )”; (14)

[0120] f3(t a +t b +t a )'=V p ; (15)

[0121] f3(T)”=0;(16)

[0122] 2t a +t b +t c =T; (17)

[0123] f3(t a +t b +t a )=f4(t a +t b +t a );(18)

[0124] f3(t a +t b +t a )'=f4(t a +b+t a )';(19)

[0125] -f1(0)”'=f2(t a +t b )”'=J;(20)

[0126] Where T is the total planning trajectory time length of the first longitudinal trajectory, the second longitudinal trajectory, the third longitudinal trajectory and the fourth longitudinal trajectory, t a is the time between the first and third longitudinal trajectories, t b is the time of the second longitudinal trajectory, t c is the time of the fourth longitudinal trajectory, V0 is the initial speed of the vehicle, J is a constant, V p is the current speed of the preceding vehicle (when the distance between the vehicle and the preceding vehicle is less than or equal to the preset distance f3(t a +t b +t a )'=V p ), f1(0) represents the displacement of the vehicle at the beginning of the first longitudinal trajectory.

[0127] As can be seen from the above, formula (6) indicates that in the local coordinate system, the starting position of the vehicle is the origin, and at time t = 0, the longitudinal displacement of the vehicle at the beginning of the first longitudinal trajectory is 0. Formula (7) indicates that the starting speed of the longitudinal trajectory of the vehicle is the actual longitudinal speed V0 of the vehicle, and V0 is known; Formula (8) indicates that the longitudinal acceleration of the vehicle at the starting position is 0; Formula (9) indicates that the longitudinal displacement of the first longitudinal trajectory and the second longitudinal trajectory is continuous; Formula (10) indicates that the longitudinal speed of the first longitudinal trajectory and the second longitudinal trajectory is continuous; Formula (11) indicates that the longitudinal acceleration of the first longitudinal trajectory and the second longitudinal trajectory is equal; Formula (12) indicates that the longitudinal displacement of the second longitudinal trajectory and the third longitudinal trajectory is continuous; Formula (13) indicates that the longitudinal speed of the second longitudinal trajectory and the third longitudinal trajectory is continuous; Formula (14) indicates that the longitudinal acceleration of the second longitudinal trajectory and the third longitudinal trajectory is equal; Formula (15) indicates that the longitudinal speed at the end of the third longitudinal trajectory can be equal to the current speed V of the target vehicle in front p , V p It is known that it can be obtained from the perception system (when the distance between the self-vehicle and the front vehicle is less than or equal to the preset distance); formula (16) indicates that the longitudinal acceleration at the end of the third longitudinal trajectory is 0; the total planned trajectory time length T in formula (17) is known, and in some examples it can be 8 seconds; formula (18) indicates that the longitudinal displacement at the connection position of the third longitudinal trajectory and the fourth longitudinal trajectory is continuous; formula (19) indicates that the longitudinal speed at the connection position of the third longitudinal trajectory and the fourth longitudinal trajectory is continuous; formula (20) indicates that the acceleration change rate jerk of the first longitudinal trajectory and the third longitudinal trajectory is a constant J, and J is known to be 4, and its physical meaning indicates that the self-vehicle accelerates or decelerates to the expected value at the maximum acceleration change rate.

[0128] From the above, for the above formula (15), when the distance between the vehicle and the front vehicle is less than or equal to the preset distance (for example, 100 meters), the target speed is the current speed V of the front vehicle. p When the distance between the vehicle and the preceding vehicle is greater than the preset distance, the target speed may be a first preset speed value V s1 , the first preset speed value can be set by the driver.

[0129] In other embodiments, when the solution of the equation does not satisfy the constraint, for example, when the current speed of the ego vehicle is greater than the preset speed limit, or the current acceleration of the ego vehicle is greater than the preset acceleration limit, the ego vehicle speed V0 and the front vehicle speed V p Or the vehicle speed V0 and the first preset speed value V s1 The gap is too large; the target speed may be subjected to a golden section to obtain an updated target speed.

[0130] Exemplarily, the update is performed according to the following formula: p =V0+(V p -V0)×0.618. Where V0 is the vehicle speed.

[0131] By performing one or more of the golden sections above, the target speed is iteratively updated until the target speed meets the requirements, and the final target speed can be obtained.

[0132] In some preferred embodiments, solving the following vehicle model to obtain a solution result includes: sampling the solution result of the following vehicle model within a preset sampling interval to obtain the multiple analytical solutions, and determining the multiple analytical solutions as the solution result; wherein the sampling interval is [0, T], and T represents the total planned trajectory time length of the first longitudinal trajectory, the second longitudinal trajectory, the third longitudinal trajectory and the fourth longitudinal trajectory.

[0133] For example, assuming that t a +t b +t a =T s , T s Unknown, then for T s Sampling is performed, the number of sampling points is 30, and the sampling interval is [0, T]. The physical meaning is that the ideal state must be reached within the planned time. At this time, multiple analytical solutions can be obtained. For example, in the acceleration scene, the acceleration curve is as follows Figure 6 As shown in the deceleration scenario, the acceleration curve is as follows Figure 7 shown.

[0134] In some preferred embodiments, the cost of each analytical solution can be calculated by a preset cost function, and the analytical solution with the minimum cost is selected, and the speed of the vehicle is controlled based on the analytical solution with the minimum cost;

[0135] The preset cost function includes:

[0136] f cost =w1×cost speed +w2×cost comfort +w3×cost collision +w4×cost centerAcc +

[0137] w5×cost follow ;

[0138] cost speed =|f4(T)'-V s2 |;

[0139] costcomfort =|f2(t a )"|;

[0140]

[0141] cost2=V t ×V t ×k;

[0142]

[0143] cost3=max(0,X t -X safet );

[0144] Among them, f cost is the cost function, cost speed Cost is the speed cost. comfort Cost of comfort collision is the collision cost, cost centerAcc is the centripetal acceleration cost, cost follow is the stable following cost, w1, w2, w3, w4 and w5 are the weights corresponding to the cost function, speed cost, comfort cost, collision cost, centripetal acceleration cost and stable following cost respectively, k represents the lane curvature of the vehicle, V t represents the longitudinal velocity of the vehicle at time t, X t represents the longitudinal displacement of the vehicle at time t, X tfront represents the longitudinal displacement of the preceding vehicle at time t (if there is no preceding vehicle, the value can be -1000 meters), f4(T)' represents the longitudinal velocity of the vehicle at the end of the fourth longitudinal trajectory, and f2(t a )” represents the longitudinal acceleration at the initial moment of the second longitudinal trajectory, V s2 is the second preset speed value, X safet It represents the safety distance at the tth moment, and cost1, cost2 and cost3 are intermediate variables.

[0145] The curvature k of the lane where the vehicle is located can be obtained from the map data. The speed cost can be expressed as the absolute value of the difference between the longitudinal speed of the vehicle at the end of the fourth longitudinal trajectory and the second preset speed value to express the cost of reaching the set speed. The comfort cost can be expressed as the absolute value of the difference between the longitudinal speed of the vehicle at the end of the fourth longitudinal trajectory and the second preset speed value to express the cost of reaching the set speed. a The acceleration at the moment is used as the comfort cost of the analytical solution, and the greater the acceleration, the more uncomfortable it is.

[0146] The cost of each analytical solution is obtained through the above-mentioned preset cost function, and then the analytical solution with the smallest cost is selected for the speed control of the vehicle. This can take into account factors such as speed, comfort, collision, centripetal acceleration and stable following, ensuring that the user is comfortable, stable and low-risk during the following vehicle driving.

[0147] like Figure 8 As shown, the present invention also provides a speed control device 800, which includes an acquisition module 801 and a control module 802; wherein,

[0148] The acquisition module 801 is used to acquire a vehicle following model under the condition that a safe distance between the vehicle and the preceding vehicle is satisfied, wherein the vehicle following model includes a motion equation describing multiple longitudinal trajectories, wherein the motion equation describes the relationship between the displacement of the vehicle in the longitudinal trajectory and time;

[0149] The control module 802 is used to solve the following vehicle model to obtain a solution result; and control the speed of the vehicle based on the solution result;

[0150] The multiple longitudinal trajectories include a first longitudinal trajectory, a second longitudinal trajectory, a third longitudinal trajectory and a fourth longitudinal trajectory; the acceleration change rate of the first longitudinal trajectory is equal to the acceleration change rate of the third longitudinal trajectory, and the acceleration of the second longitudinal trajectory and the acceleration of the fourth longitudinal trajectory are constant values.

[0151] In some preferred technical solutions, the motion equation of the first longitudinal trajectory is:

[0152] f1(t)=a0×t 3 +b0×t 2 +c0t+d0;

[0153] The motion equation of the second longitudinal trajectory is:

[0154] f2(t)=a1×t 2 +b1×t+c1;

[0155] The motion equation of the third longitudinal trajectory is:

[0156] f3(t)=a2×t 3 +b2×t 2 +c2×t+d2;

[0157] The motion equation of the fourth longitudinal trajectory is:

[0158] f4(t)=a3t+b3;

[0159] Among them, f1(t) is the displacement of the vehicle at the tth moment in the first longitudinal trajectory, f2(t) is the displacement of the vehicle at the tth moment in the second longitudinal trajectory, f3(t) is the displacement of the vehicle at the tth moment in the third longitudinal trajectory, f4(t) is the displacement of the vehicle at the tth moment in the fourth longitudinal trajectory, and a0, b0, c0, d0, a1, b1, c1, a2, b2, c2, d2, a3 and b3 are all parameters to be solved.

[0160] In some preferred technical solutions, the control module 802 solves the vehicle following model to obtain a solution result, including:

[0161] The control module 802 solves the vehicle following model under the preset constraint conditions to obtain the solution result;

[0162] The preset constraint conditions include: the longitudinal displacement of the connection position of the first longitudinal trajectory and the second longitudinal trajectory is continuous, the longitudinal speed of the connection position of the first longitudinal trajectory and the second longitudinal trajectory is continuous, the longitudinal acceleration of the connection position of the first longitudinal trajectory and the second longitudinal trajectory is equal, the longitudinal displacement of the connection position of the second longitudinal trajectory and the third longitudinal trajectory is continuous, the longitudinal speed of the connection position of the second longitudinal trajectory and the third longitudinal trajectory is continuous, the longitudinal acceleration of the connection position of the second longitudinal trajectory and the third longitudinal trajectory is equal, the longitudinal speed at the end of the third longitudinal trajectory is the target speed, the longitudinal acceleration at the end of the third longitudinal trajectory is zero, the longitudinal displacement of the connection position of the third longitudinal trajectory and the fourth longitudinal trajectory is continuous, the longitudinal speed of the connection position of the third longitudinal trajectory and the fourth longitudinal trajectory is continuous, the longitudinal acceleration change rate of the first longitudinal trajectory and the second longitudinal trajectory is a constant, and the total planned trajectory time length of the first longitudinal trajectory, the second longitudinal trajectory, the third longitudinal trajectory and the fourth longitudinal trajectory is a preset value.

[0163] In some preferred technical solutions, the control module 802 solves the vehicle following model to obtain a solution result, including:

[0164] The control module 802 samples the solution results of the vehicle following model within a preset sampling interval to obtain the multiple analytical solutions, and determines the multiple analytical solutions as the solution results; wherein the sampling interval is [0, T], T represents the total planned trajectory time length of the first longitudinal trajectory, the second longitudinal trajectory, the third longitudinal trajectory and the fourth longitudinal trajectory.

[0165] In some preferred technical solutions, the control module 802 controls the speed of the vehicle based on the solution result, including:

[0166] The control module 802 calculates the cost of each analytical solution through a preset cost function, selects the analytical solution with the minimum cost, and controls the speed of the vehicle based on the analytical solution with the minimum cost;

[0167] The preset cost function includes:

[0168] f cost =w1×cost speed +w2×cost comfort +w3×cost collision +w4×cost centerAcc +

[0169] w5×cost follow ;

[0170] cost speed =|f4(T)'-V s2 |;

[0171] cost comfort =|f2(t a )"|;

[0172]

[0173] cost2=V t ×V t ×k;

[0174]

[0175] cost3=max(0,X t -X safet );

[0176] Among them, f cost is the cost function, cost speed Cost is the speed cost. comfort Cost of comfort collision is the collision cost, cost centerAcc is the centripetal acceleration cost, cost follow is the stable following cost, w1, w2, w3, w4 and w5 are the weights corresponding to the cost function, speed cost, comfort cost, collision cost, centripetal acceleration cost and stable following cost respectively, k represents the lane curvature of the vehicle, V t represents the longitudinal velocity of the vehicle at time t, X t represents the longitudinal displacement of the vehicle at time t, X tfront represents the longitudinal displacement of the leading vehicle at time t, f4(T)' represents the longitudinal velocity of the vehicle at the end of the fourth longitudinal trajectory, and f2(t a)” represents the longitudinal acceleration at the initial moment of the second longitudinal trajectory, V s is the second preset speed value, X safet It represents the safety distance at the tth moment, and cost1, cost2 and cost3 are intermediate variables.

[0177] In some preferred technical solutions, when the distance between the vehicle and the leading vehicle is less than or equal to a preset distance, the target speed is the current speed of the leading vehicle; when the distance between the vehicle and the leading vehicle is greater than the preset distance, the target speed is a first preset speed value.

[0178] In some preferred technical solutions, the speed control device 800 also includes an update module, which is used to perform golden section on the target speed to obtain an updated target speed when the current speed of the vehicle is greater than a preset speed limit, or the current acceleration of the vehicle is greater than a preset acceleration limit.

[0179] In addition, the present invention application also provides a terminal device, including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, and the processor implements the speed control method when executing the computer program.

[0180] The processor may be a central processing unit (CPU), other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor, etc. The processor is the control center of the terminal, and various interfaces and lines are used to connect various parts of the entire terminal.

[0181] The memory can be used to store the computer program, and the processor realizes various functions of the terminal by running or executing the computer program stored in the memory and calling the data stored in the memory. The memory can mainly include a program storage area and a data storage area, wherein the program storage area can store an operating system, an application required for at least one function (such as a sound playback function, an image playback function, etc.), etc.; the data storage area can store data created according to the use of the mobile phone (such as audio data, a phone book, etc.), etc. In addition, the memory can include a high-speed random access memory, and can also include a non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a smart memory card (SmartMedia Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), at least one disk storage device, a flash memory device, or other volatile solid-state storage devices.

[0182] Correspondingly, the present invention application also provides a computer-readable storage medium, which includes a stored computer program, wherein when the computer program is running, the device where the computer-readable storage medium is located is controlled to execute the speed control method.

[0183] Wherein, if the module integrated in the speed control device is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on such an understanding, the present invention implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned various method embodiments when executed by the processor. Wherein, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form, etc. The computer-readable medium can include: any entity or device capable of carrying the computer program code, recording medium, U disk, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), electric carrier signal, telecommunication signal and software distribution medium, etc.

[0184] Compared with the prior art, the embodiments of the present application have at least the following beneficial effects:

[0185] The present invention application provides a speed control method, device, equipment and computer-readable storage medium, the method comprising: obtaining a following vehicle model under the condition of satisfying a safe distance between a self-vehicle and a leading vehicle, the following vehicle model comprising a motion equation describing multiple longitudinal trajectories, the motion equation describing the relationship between the displacement of the self-vehicle in the longitudinal trajectory and time; solving the following vehicle model to obtain a solution result; and controlling the speed of the self-vehicle based on the solution result; wherein the multiple longitudinal trajectories comprise a first longitudinal trajectory, a second longitudinal trajectory, a third longitudinal trajectory and a fourth longitudinal trajectory; the acceleration change rate of the first longitudinal trajectory is equal to the acceleration change rate of the third longitudinal trajectory, and the acceleration of the second longitudinal trajectory and the acceleration of the fourth longitudinal trajectory are constant values. The following vehicle model applied for in the present invention includes motion equations of multiple longitudinal trajectories, which describe the relationship between the displacement of the ego vehicle in the longitudinal trajectory and time. By designing the above-mentioned multiple longitudinal trajectories in the following vehicle model, that is, there are multiple control segment points in the following vehicle process, compared with the control scheme of the prior art using a quintic polynomial or a quartic polynomial, not only the starting and ending states are constrained, but also the ego vehicle state at each control segment point is constrained, thereby ensuring the controllability of the starting state, the ending state and the intermediate state during the ego vehicle following vehicle driving process; in addition, the multiple longitudinal trajectories include a first longitudinal trajectory, a second longitudinal trajectory, a third longitudinal trajectory and a fourth longitudinal trajectory, the acceleration change rate of the first longitudinal trajectory is equal to the acceleration change rate of the third longitudinal trajectory, and the acceleration of the second longitudinal trajectory and the acceleration of the fourth longitudinal trajectory are constant values, so that the speed change of the ego vehicle during the whole following vehicle driving process is relatively smooth, which optimizes the user experience while ensuring the stability of the following vehicle driving.

[0186] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. It is particularly pointed out that for those skilled in the art, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A speed control method, characterized in that: include: Under the condition that a safe distance between the ego vehicle and the preceding vehicle is satisfied, a vehicle following model is obtained, wherein the vehicle following model includes a motion equation describing multiple longitudinal trajectories, and the motion equation describes a relationship between a displacement of the ego vehicle in the longitudinal trajectory and time; Solving the following vehicle model to obtain a solution result; and controlling the speed of the self-vehicle based on the solution result; The multiple longitudinal trajectories include a first longitudinal trajectory, a second longitudinal trajectory, a third longitudinal trajectory and a fourth longitudinal trajectory; the acceleration change rate of the first longitudinal trajectory is equal to the acceleration change rate of the third longitudinal trajectory, and the acceleration of the second longitudinal trajectory and the acceleration of the fourth longitudinal trajectory are constant values.

2. A speed control method as claimed in claim 1, characterized in that: The motion equation of the first longitudinal trajectory is: f1(t)=a0×t 3 +b0×t 2 +c0t+d0; The motion equation of the second longitudinal trajectory is: f2(t)=a1×t 2 +b1×t+c1; The motion equation of the third longitudinal trajectory is: <h2 style=";text-align:left;direction:ltr">f3(t) = a2×t<h2 style=";text-align:left;direction:ltr"> 3 <h2 style=";text-align:left;direction:ltr"> +b2×t<h2 style=";text-align:left;direction:ltr"> 2 <h2 style=";text-align:left;direction:ltr"> +c2×t+d2; The motion equation of the fourth longitudinal trajectory is: f4(t)=a3t+b3; Among them, f1(t) is the displacement of the vehicle at the tth moment in the first longitudinal trajectory, f2(t) is the displacement of the vehicle at the tth moment in the second longitudinal trajectory, f3(t) is the displacement of the vehicle at the tth moment in the third longitudinal trajectory, f4(t) is the displacement of the vehicle at the tth moment in the fourth longitudinal trajectory, and a0, b0, c0, d0, a1, b1, c1, a2, b2, c2, d2, a3 and b3 are all parameters to be solved.

3. A speed control method as claimed in claim 2, characterized in that: The method of solving the vehicle following model to obtain a solution result includes: Under the preset constraint conditions, solving the vehicle following model to obtain the solution result; The preset constraint conditions include: the longitudinal displacement of the connection position of the first longitudinal trajectory and the second longitudinal trajectory is continuous, the longitudinal speed of the connection position of the first longitudinal trajectory and the second longitudinal trajectory is continuous, the longitudinal acceleration of the connection position of the first longitudinal trajectory and the second longitudinal trajectory is equal, the longitudinal displacement of the connection position of the second longitudinal trajectory and the third longitudinal trajectory is continuous, the longitudinal speed of the connection position of the second longitudinal trajectory and the third longitudinal trajectory is continuous, the longitudinal acceleration of the connection position of the second longitudinal trajectory and the third longitudinal trajectory is equal, the longitudinal speed at the end of the third longitudinal trajectory is the target speed, the longitudinal acceleration at the end of the third longitudinal trajectory is zero, the longitudinal displacement of the connection position of the third longitudinal trajectory and the fourth longitudinal trajectory is continuous, the longitudinal speed of the connection position of the third longitudinal trajectory and the fourth longitudinal trajectory is continuous, the longitudinal acceleration change rate of the first longitudinal trajectory and the second longitudinal trajectory is a constant, and the total planned trajectory time length of the first longitudinal trajectory, the second longitudinal trajectory, the third longitudinal trajectory and the fourth longitudinal trajectory is a preset value.

4. A speed control method as claimed in claim 1, characterized in that: The method of solving the vehicle following model to obtain a solution result includes: The solution result of the following vehicle model is sampled within a preset sampling interval to obtain the multiple analytical solutions, and the multiple analytical solutions are determined as the solution result; wherein the sampling interval is [0, T], and T represents the total planned trajectory time length of the first longitudinal trajectory, the second longitudinal trajectory, the third longitudinal trajectory and the fourth longitudinal trajectory.

5. A speed control method as claimed in claim 4, characterized in that: The controlling the speed of the vehicle based on the solution result includes: Calculating the cost of each analytical solution through a preset cost function, selecting the analytical solution with the minimum cost, and controlling the speed of the vehicle based on the analytical solution with the minimum cost; The preset cost function includes: f cost =w1×cost speed +w2×cost comfort +w3×cost collision +w4×cost centerAcc + w5×cost follow ; cost speed =|f4(T)'-V s2 |; cost comfort =|f2(t a )”|; cost2=V t ×V t ×k; cost3=max(0,X t -X safet ); Among them, f cost is the cost function, cost speed Cost is the speed cost. comfort Cost of comfort collision is the collision cost, cost centerAcc is the centripetal acceleration cost, cost follow is the stable following cost, w1, w2, w3, w4 and w5 are the weights corresponding to the cost function, speed cost, comfort cost, collision cost, centripetal acceleration cost and stable following cost respectively, k represents the lane curvature of the vehicle, V t represents the longitudinal velocity of the vehicle at time t, X t represents the longitudinal displacement of the vehicle at time t, X tfront represents the longitudinal displacement of the leading vehicle at time t, f4(T)' represents the longitudinal velocity of the vehicle at the end of the fourth longitudinal trajectory, and f2(t a )” represents the longitudinal acceleration at the initial moment of the second longitudinal trajectory, V s is the second preset speed value, X safet It represents the safety distance at the tth moment, and cost1, cost2 and cost3 are intermediate variables.

6. A speed control method as claimed in claim 3, characterized in that: The speed control method further comprises: When the distance between the vehicle and the front vehicle is less than or equal to a preset distance, the target speed is the current speed of the front vehicle; When the distance between the vehicle and the preceding vehicle is greater than the preset distance, the target speed is a first preset speed value.

7. A speed control method as claimed in claim 3, characterized in that: The speed control method further comprises: When the current speed of the vehicle is greater than the preset speed limit, or the current acceleration of the vehicle is greater than the preset acceleration limit, the target speed is subjected to a golden section to obtain an updated target speed.

8. A speed control device, characterized in that: The speed control device includes an acquisition module and a control module; wherein, The acquisition module is used to acquire a vehicle following model under the condition that a safe distance between the vehicle and the preceding vehicle is satisfied, wherein the vehicle following model includes a motion equation describing multiple longitudinal trajectories, wherein the motion equation describes the relationship between the displacement of the vehicle in the longitudinal trajectory and time; The control module is used to solve the following vehicle model to obtain a solution result; and control the speed of the vehicle based on the solution result; The multiple longitudinal trajectories include a first longitudinal trajectory, a second longitudinal trajectory, a third longitudinal trajectory and a fourth longitudinal trajectory; the acceleration change rate of the first longitudinal trajectory is equal to the acceleration change rate of the third longitudinal trajectory, and the acceleration of the second longitudinal trajectory and the acceleration of the fourth longitudinal trajectory are constant values.

9. A terminal device, characterized in that: The method comprises a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein the processor implements the speed control method according to any one of claims 1 to 7 when executing the computer program.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium includes a stored computer program, wherein when the computer program is executed, the device where the computer-readable storage medium is located is controlled to execute the speed control method according to any one of claims 1 to 7.

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