Acceleration control method and system and vehicle

Abstract

The invention provides an acceleration control method and system and a vehicle, and the method specifically comprises the following steps: (1) the current vehicle speed vf and acceleration af, the current vehicle speed vx of the vehicle and the actual vehicle distance L between the vehicle and a front vehicle are collected in real time, and the expected front acceleration ax required by the change of input parameters near a sliding mode surface is determined; and (2) the difference value ax-a between the expected acceleration ax and the current acceleration a (t) of the vehicle serves as the current deviation value e (t), and the variable quantity delta a (t) of the current acceleration of the vehicle is output based on PID control, so that the acceleration of the vehicle reaches the expected acceleration ax. By defining the sliding mode surface and the approaching rate and outputting the expected acceleration ax of reasonable change of input parameters near the sliding mode surface, the safe parking distance can be guaranteed, it can be guaranteed that comfortable braking is achieved at the appropriate deceleration under the deceleration condition, and then the vehicle control stability is improved by controlling the stable variable quantity of the output acceleration of the vehicle through PID.

Description

Technical Field

[0001] The present invention relates to the field of autonomous driving technology and provides an acceleration control method, system and vehicle. Background Art

[0002] In recent years, with the development of science and technology, especially the rapid development of intelligent computing, research on autonomous driving vehicle technology has become a hot topic in various industries.

[0003] According to the technical field, autonomous driving can be divided into perception module, positioning module, prediction module, control module and execution module. The perception module is equivalent to human eyes, and collects the surrounding environment status in real time through sensors such as cameras, millimeter wave radars, and lidars. The positioning module is used to obtain the vehicle's own position information. The prediction module predicts the vehicle's own running trajectory or the trajectory of other vehicles, pedestrians, and motor vehicles. Control is the decision-making and planning of vehicle movement, and execution is the execution of the vehicle's decision-making and planning commands.

[0004] At present, in practical applications, PID controllers are often used to directly control the longitudinal speed. Although PID control has the characteristics of good stability, it is often difficult to achieve ideal control effects when facing complex and changeable road environments and external interference. Summary of the invention

[0005] In view of this, the present application provides an acceleration control method, aiming to improve the above-mentioned problem.

[0006] Specifically, the following technical solutions are included:

[0007] On the one hand, an embodiment of the present application provides an acceleration control method, and the method is specifically as follows:

[0008] (1) Collect the current vehicle speed v in real time f , acceleration a f 、The current speed of the vehicle v x As well as the actual distance L between the vehicle and the preceding vehicle, determine the expected front acceleration a required for the input parameters to change near the sliding surface. x ;

[0009] (2) The expected acceleration a x The difference a from the current acceleration a(t) of the vehicle x -a is used as the current deviation e(t), and the change in the vehicle's current acceleration Δa(t) is output based on PID control to make the vehicle's acceleration reach the desired acceleration a x .

[0010] In some embodiments of the present invention, the expected front acceleration a x The calculation formula is as follows:

[0011]

[0012] Among them, a c is the comfortable following acceleration during braking, amax is the maximum acceleration of the leading vehicle during following, S is the set sliding surface, S = C ε + ε′, C is the sliding surface coefficient, ε is the actual distance L between the vehicle and the leading vehicle and the expected distance L q , ε′ is the rate of change of the deviation ε.

[0013] In some embodiments of the present invention, the calculation formula of the function sat0(S) is as follows:

[0014]

[0015] in, is the boundary value of the change interval.

[0016] In some embodiments of the present invention, the calculation formula of the current acceleration change Δa(t) is as follows:

[0017]

[0018] Among them, K P is the proportionality coefficient, K I is the integration coefficient, K D is the differential coefficient.

[0019] On the other hand, an embodiment of the present application provides an acceleration control system, the system comprising:

[0020] The input unit, the acquisition unit, the processor and the actuator are arranged in the vehicle where the vehicle is located. The acquisition unit and the input unit are connected to the processor in communication. The processor is connected to the actuator in communication. The processor is integrated with the expected acceleration calculation model and the PID control model.

[0021] Input unit, used to set the comfortable following acceleration a during braking c , expected vehicle distance L q Input the expected acceleration calculation model and set the proportional coefficient K P , integration coefficient K I , differential coefficient K D Input PID control model;

[0022] The acquisition unit is used to collect the current vehicle speed v in real time f , acceleration a f 、The current speed of the vehicle v x , the actual distance L between the vehicle and the preceding vehicle, and sends it to the expected acceleration calculation model;

[0023] The expected acceleration calculation model outputs the expected acceleration a required for the input parameters to change near the sliding surface x ;

[0024] The expected acceleration a x The difference a from the current acceleration a(t) of the vehicle x -a is used as the current deviation e(t) and input into the PID control model. The PID control model outputs the current acceleration change Δa(t), and sends the acceleration change Δa(t) to the actuator. The actuator converts the acceleration change Δa(t) into braking force or driving force to adjust the vehicle speed.

[0025] In some embodiments of the present invention, the expected acceleration calculation model is as follows:

[0026]

[0027] Among them, S is the sliding surface, S = C·ε+ε′, C is the sliding surface coefficient, ε is the actual distance L between the vehicle and the front vehicle and the expected distance L q , ε′ is the rate of change of the deviation ε.

[0028] In some embodiments of the present invention, the calculation formula of the function sat0(S) is as follows:

[0029]

[0030] in, is the boundary value of the change interval.

[0031] In some embodiments of the present invention, the PID control model is as follows:

[0032]

[0033] The expected acceleration a x The difference a from the current acceleration a(t) of the vehicle x -a is used as the current deviation e(t) and input into the PID control model, which then outputs the current acceleration change Δa(t).

[0034] On the other hand, an embodiment of the present application provides a vehicle, which is integrated with the above-mentioned acceleration control system. When the vehicle is in an unmanned driving state or an automatic driving state, the acceleration control system is used to determine the current expected acceleration of the vehicle and control the vehicle to stably change from the current acceleration to the expected acceleration.

[0035] The present invention defines the sliding surface and the approach rate, outputs the input parameters (current vehicle speed v f 、The current speed of the vehicle v xAs well as the actual distance L between the vehicle and the vehicle in front and the maximum acceleration a of the vehicle in front during the following process max ) The expected acceleration a that changes reasonably near the sliding surface x It can not only ensure safe stopping distance, but also ensure comfortable braking with appropriate deceleration under deceleration conditions, and then control the change of the vehicle's stable output acceleration through PID to improve the stability of vehicle control. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0037] Figure 1 A flowchart of an acceleration control method provided by an embodiment of the present invention;

[0038] Figure 2 A schematic diagram of the structure of an acceleration control system provided by an embodiment of the present invention;

[0039] The above drawings have shown clear embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0041] Unless otherwise defined, all technical terms used in the embodiments of the present application have the same meanings as commonly understood by those of ordinary skill in the art.

[0042] Figure 1 This is a flow chart of an acceleration control method provided by an embodiment of the present invention, and the method is specifically as follows:

[0043] (1) Collect the current vehicle speed v in real time f , acceleration a f 、The current speed of the vehicle v x As well as the actual distance L between the vehicle and the preceding vehicle, determine the expected front acceleration a required for the input parameters to change near the sliding surface. x ;

[0044] In the embodiment of the present invention, the minimum following distance L of the vehicle is set min Comfortable following acceleration during braking c , based on the actual distance L between the vehicle and the preceding vehicle and the expected distance L q The sliding surface S is defined by the deviation ε and the rate of change of the deviation ε. The sliding surface S is as follows:

[0045] S=C·ε+ε′ (1)

[0046] Where C is the sliding surface coefficient, ε′ is the difference between the actual distance L and the expected distance L q The rate of change of the deviation ε.

[0047] In the actual following process, the actual distance L between the two vehicles is different from the expected distance L q The deviation ε can be approximated as:

[0048]

[0049] Where L is the actual distance between the vehicle and the vehicle in front, v f is the current speed of the preceding vehicle, v x is the current speed of the vehicle, a max is the maximum acceleration of the preceding vehicle during the following process;

[0050] Among them, the rate of change ε′ of the deviation ε can be approximated as:

[0051] ε′=v r =v f -v x (3)

[0052] Substituting formula (2) and formula (3) into formula (1), we can get:

[0053]

[0054] By taking the derivative of formula (4), we can get:

[0055]

[0056] The approach rate of the sliding surface is designed using the sat function, as follows:

[0057]

[0058] in, is the boundary value of the changing interval. In order to effectively alleviate the shaking phenomenon of the vehicle, the function sat(S) is further smoothed to obtain the function sat0(S). The expression of the function sat0(S) is as follows:

[0059]

[0060] So the approach rate function is:

[0061]

[0062] Among them, k is the exponential coefficient and ε is the constant velocity coefficient.

[0063] Combining formula (5) with formula (8), we can obtain the expected acceleration a after sliding mode control adjustment: c for:

[0064]

[0065] Among them, a f is the current acceleration of the front vehicle.

[0066] (2) The expected acceleration a x The difference a from the current acceleration a(t) of the vehicle x -a is used as the current deviation e(t), and the change in the current acceleration of the vehicle is output based on PID control Δa(t), which controls the change in the stable output acceleration of the vehicle so that the acceleration of the vehicle reaches the desired acceleration a x ;

[0067] In the embodiment of the present invention, the PID control formula is as follows:

[0068]

[0069] Among them, K P is the proportionality coefficient, K I is the integration coefficient, K D is the differential coefficient.

[0070] The present invention defines the sliding surface and the approach rate, outputs the input parameters (current vehicle speed v f 、The current speed of the vehicle v x As well as the actual distance L between the vehicle and the vehicle in front and the maximum acceleration a of the vehicle in front during the following process max ) The expected acceleration a that changes reasonably near the sliding surface x It can not only ensure safe stopping distance, but also ensure comfortable braking with appropriate deceleration under deceleration conditions, and then control the change of the vehicle's stable output acceleration through PID to improve the stability of vehicle control.

[0071] Figure 2 The schematic diagram of the structure of the acceleration control system provided by the embodiment of the present invention, for the convenience of description, only the part related to the embodiment of the present invention is shown, the system comprises:

[0072] The input unit, the acquisition unit, the processor and the actuator are arranged in the vehicle where the vehicle is located. The acquisition unit and the input unit are connected to the processor in communication. The processor is connected to the actuator in communication. The processor is integrated with the expected acceleration calculation model and the PID control model.

[0073] Input unit, used to set the comfortable following acceleration a during braking c , expected vehicle distance L q Input the expected acceleration calculation model and set the proportional coefficient K P , integration coefficient K I , differential coefficient K D Input PID control model;

[0074] The acquisition unit is used to collect the current vehicle speed v in real time f , acceleration a f 、The current speed of the vehicle v x , the actual distance L between the vehicle and the preceding vehicle, and sends it to the expected acceleration calculation model; the expected acceleration calculation model outputs the expected acceleration a required for the input parameters to change near the sliding surface x ; Set the expected acceleration a x The difference a from the current acceleration a(t) of the vehicle x -a is used as the current deviation e(t) and input into the PID control model. The PID control model outputs the current acceleration change Δa(t), which is sent to the actuator. The actuator converts the acceleration change Δa(t) into braking force or driving force to adjust the vehicle speed and control the change in the output acceleration of the vehicle to stabilize the vehicle so that the vehicle's acceleration reaches the desired acceleration a. x .

[0075] In the embodiment of the present invention, the expected acceleration calculation model is specifically as follows:

[0076]

[0077] Among them, S is the sliding surface, S = C·ε+ε′, C is the sliding surface coefficient, ε is the actual distance L between the vehicle and the front vehicle and the expected distance L q The deviation of ε′ is the rate of change of the deviation ε, and the expression of the function sat0(S) is as follows:

[0078]

[0079] in, is the boundary value of the change interval.

[0080] In the embodiment of the present invention, the PID control model is as follows:

[0081]

[0082] The expected acceleration a x The difference a from the current acceleration a(t) of the vehicle x -a is used as the current deviation e(t) and input into the PID control model, which then outputs the current acceleration change Δa(t).

[0083] The present invention defines a sliding surface and a convergence rate, and outputs an expected acceleration a of a reasonable change of input parameters near the sliding surface. x It can not only ensure safe stopping distance, but also ensure comfortable braking with appropriate deceleration under deceleration conditions, and then control the change of the vehicle's stable output acceleration through PID to improve the stability of vehicle control.

[0084] Another embodiment of the present invention provides a vehicle that is integrated with the above-mentioned acceleration control system. When the vehicle is in an unmanned driving state or an automatic driving state, the acceleration control system is used to determine the current desired acceleration of the vehicle, and control the vehicle to stably change from the current acceleration to the desired acceleration, thereby ensuring both a safe parking distance and comfortable braking with an appropriate deceleration under deceleration conditions.

[0085] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the present application disclosed herein. The present application is intended to cover any variations, uses or adaptations of the present application, which follow the general principles of the present application and include common knowledge or customary techniques in the art that are not disclosed in the present application. The specification and examples are intended to be exemplary only.

[0086] It should be understood that the present application is not limited to the precise structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. An acceleration control method, characterized in that: The method is specifically as follows: (1) Collect the current vehicle speed v in real time f , acceleration a f 、The current speed of the vehicle v x As well as the actual distance L between the vehicle and the preceding vehicle, determine the expected front acceleration a required for the input parameters to change near the sliding surface. x ; (2) The expected acceleration a x The difference a from the current acceleration a(t) of the vehicle x -a is used as the current deviation e(t), and the change in the vehicle's current acceleration Δa(t) is output based on PID control to make the vehicle's acceleration reach the desired acceleration a x .

2. The acceleration control method according to claim 1, characterized in that: Expected forward acceleration a x The calculation formula is as follows: Among them, a c is the comfortable following acceleration during braking, a max is the maximum acceleration of the leading vehicle during the following process, S is the set sliding surface, S = C·ε+ε′, C is the sliding surface coefficient, ε is the actual distance L between the vehicle and the leading vehicle and the expected distance L q , ε′ is the rate of change of the deviation ε.

3. The acceleration control method according to claim 2, characterized in that: The calculation formula of the function sat0(S) is as follows: in, is the boundary value of the change interval.

4. The acceleration control method according to claim 1, characterized in that: The calculation formula of the current acceleration change Δa(t) is as follows: Among them, K P is the proportionality coefficient, K I is the integration coefficient, K D is the differential coefficient.

5. An acceleration control system, characterized in that: The system comprises: The input unit, the acquisition unit, the processor and the actuator are arranged in the vehicle where the vehicle is located. The acquisition unit and the input unit are connected to the processor in communication. The processor is connected to the actuator in communication. The processor is integrated with the expected acceleration calculation model and the PID control model. Input unit, used to set the comfortable following acceleration a during braking c , expected vehicle distance L q Input the expected acceleration calculation model and set the proportional coefficient K P , integration coefficient K I , differential coefficient K D Input PID control model; The acquisition unit is used to collect the current vehicle speed v in real time f , acceleration a f 、The current speed of the vehicle v x , the actual distance L between the vehicle and the vehicle in front, and send it to the expected acceleration calculation model; The expected acceleration calculation model outputs the expected acceleration a required for the input parameters to change near the sliding surface x ; The expected acceleration a x The difference a from the current acceleration a(t) of the vehicle x -a is used as the current deviation e(t) and input into the PID control model. The PID control model outputs the current acceleration change Δa(t), and sends the acceleration change Δa(t) to the actuator. The actuator converts the acceleration change Δa(t) into braking force or driving force to adjust the vehicle speed.

6. The acceleration control system according to claim 5, characterized in that: The expected acceleration calculation model is as follows: Among them, S is the sliding surface, S = C·ε+ε′, C is the sliding surface coefficient, ε is the actual distance L between the vehicle and the front vehicle and the expected distance L q , ε′ is the rate of change of the deviation ε.

7. The acceleration control system according to claim 6, characterized in that: The calculation formula of the function sat0(S) is as follows: in, is the boundary value of the change interval.

8. The acceleration control system according to claim 5, characterized in that: The PID control model is as follows: The expected acceleration a x The difference a from the current acceleration a(t) of the vehicle x -a is used as the current deviation e(t) and input into the PID control model, which then outputs the current acceleration change Δa(t).

9. A vehicle, characterized in that: The vehicle is integrated with an acceleration control system as described in any one of claims 5 to 8. When the vehicle is in an unmanned driving state or an automatic driving state, the acceleration control system is used to determine the current expected acceleration of the vehicle and control the vehicle to stably change from the current acceleration to the expected acceleration.

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