An acceleration control method, system and vehicle

Abstract

This invention provides an acceleration control method, system, and vehicle. The method is as follows: (1) Real-time acquisition of the current vehicle speed v f acceleration a f The current speed of this vehicle, v x Given the actual distance L between this vehicle and the vehicle in front, determine the desired forward acceleration a required for the input parameters to change near the sliding surface. x (2) The desired acceleration a x The difference a from the current acceleration a(t) of the vehicle x -a is the current deviation e(t), and the PID control outputs the change in the vehicle's current acceleration Δa(t) to make the vehicle's acceleration reach the desired acceleration a. x By defining the sliding surface and the approach rate, the desired acceleration 'a' of the input parameters is output as the input parameters reasonably vary near the sliding surface. x It can ensure a safe stopping distance and achieve comfortable braking with appropriate deceleration under deceleration conditions. Furthermore, by controlling the change in stable output acceleration of the vehicle through PID control, the stability of vehicle control is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of automatic driving, and provides an acceleration control method, system and vehicle. BACKGROUND

[0002] In recent years, with the development of technology, especially the rapid development of intelligent computing, the research on automatic driving vehicle technology has become a focus of various industries.

[0003] According to the technical field, automatic driving can be divided into a perception module, a positioning module, a prediction module, a control module and an execution module. The perception module is equivalent to the eyes of a person, which collects the surrounding environment state in real time through sensors such as cameras, millimeter wave radars and laser radars. The positioning module is used to obtain the position information of the vehicle itself. The prediction module is used to predict the running track of the vehicle itself or the track of other vehicles, pedestrians and motor vehicles. The control is the decision and planning of the movement of the vehicle, and the execution is the execution of the decision and planning command of the vehicle.

[0004] At present, in actual application, a PID controller is usually used to directly control the longitudinal speed. Although the PID control has the characteristics of good stability, it is difficult to achieve ideal control effect when facing complex and changeable road environment and external interference. SUMMARY

[0005] In view of this, the present application provides an acceleration control method, which aims to improve the above problems.

[0006] Specifically, the technical scheme comprises the following:

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

[0008] (1) Real-time collection of the current vehicle speed v f , acceleration a f , the current vehicle speed v x of the vehicle and the actual vehicle distance L between the vehicle and the front vehicle to determine the expected front acceleration a x required for the change of the input parameter in the sliding surface vicinity.

[0009] (2) Taking the difference a x between the expected acceleration a x and the current acceleration a(t) of the vehicle as the current deviation e(t), and outputting the change amount Δa(t) of the current acceleration of the vehicle based on the PID control, so that the acceleration of the vehicle reaches the expected acceleration a x .

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

[0011]

[0012] Among them, a c The set comfortable following acceleration during braking is defined by: amax, the maximum acceleration of the preceding vehicle during the following process, S, the set sliding surface, S = C·ε + ε′, where C is the sliding surface coefficient, and ε is the difference between the actual distance L and the desired distance L between the current vehicle and the preceding vehicle. q The deviation is ε′, where ε′ is the rate of change of the deviation ε.

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

[0014]

[0015] in, These are the boundary values ​​of the variation range.

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

[0017]

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

[0019] On the other hand, embodiments of this application provide an acceleration control system, the system comprising:

[0020] The system includes an input unit, a data acquisition unit, a processor, and an actuator. The data acquisition unit and the input unit are communicatively connected to the processor, and the processor is communicatively connected to the actuator. The processor integrates a desired acceleration calculation model and a PID control model.

[0021] The input unit is used to input the set comfort following acceleration a during braking. c Expected vehicle distance L q Input the desired acceleration calculation model and set the proportional coefficient K. P Integral coefficient K I Differential coefficient K D Input the PID control model;

[0022] The data acquisition unit is used to collect the current vehicle speed v in real time. f acceleration a f The current speed of this vehicle, v x The actual distance L between this vehicle and the vehicle in front is calculated and sent to the desired acceleration calculation model;

[0023] The desired acceleration calculation model outputs the desired acceleration a x ;

[0024] The difference a x between the desired acceleration a x and the current acceleration a(t) of the vehicle is taken as the current deviation e(t) and input into a PID control model, which outputs a current acceleration change amount Δa(t).

[0025] In some embodiments of the application, the desired acceleration calculation model is specifically as follows:

[0026]

[0027] where S is a sliding surface, S=C·ε+ε', C is a sliding surface coefficient, ε is the deviation of the actual vehicle distance L from the desired vehicle distance L q between the vehicle and the preceding vehicle, and ε' is the rate of change of the deviation ε.

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

[0029]

[0030] where a is a change interval boundary value.

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

[0032]

[0033] The difference a x between the desired acceleration a x and the current acceleration a(t) of the vehicle is taken as the current deviation e(t) and input into a PID control model, which outputs a current acceleration change amount Δa(t).

[0034] On the other hand, the embodiments of the application provide a vehicle integrated with the above acceleration control system, which determines the current desired acceleration of the vehicle through the acceleration control system when the vehicle is in an unmanned or automatic driving state, and controls the vehicle to change from the current acceleration to the desired acceleration stably.

[0035] The application outputs the input parameters (the current vehicle speed v f , the current vehicle speed v xThe actual distance L between the vehicle and the front vehicle and the maximum acceleration a of the front vehicle during the following process max The expected acceleration a near the sliding surface x , which can ensure safe stopping distance and suitable deceleration for comfortable braking under deceleration conditions, and then improve the stability of vehicle control by PID control of the change of the output acceleration of the vehicle. BRIEF DESCRIPTION OF DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0037] Figure 1 The flowchart of the acceleration control method provided by the embodiment of the present application;

[0038] Figure 2 The structural schematic diagram of the acceleration control system provided by the embodiment of the present application;

[0039] Through the above drawings, the specific embodiments of the present application have been shown, and more detailed description will be given in the following. These drawings and textual descriptions are not intended to limit the scope of the concept of the present application by any means, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present application will be described clearly and completely in the following by combining the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

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

[0042] Figure 1 The flowchart of the acceleration control method provided by the embodiment of the present application, which is specifically as follows:

[0043] (1) Collect the current vehicle speed v f , acceleration a f , the current vehicle speed v x of the vehicle, and the actual distance L between the vehicle and the front vehicle, to determine the expected front acceleration a x required for the change of the input parameter near the sliding surface;

[0044] In the embodiment of the present application, the minimum following distance L min of the vehicle and the comfortable following acceleration a c during braking are set q The sliding surface S is defined based on the deviation ε of the actual distance L between the vehicle and the preceding vehicle and the desired distance L q and the rate of change of the deviation ε, and the sliding surface S is specifically as follows:

[0045] S = C·ε + ε' (1)

[0046] Wherein, C is the sliding surface coefficient, and ε' is the rate of change of the deviation ε of the actual distance L and the desired distance L

[0047] During actual following, the deviation ε of the actual distance L and the desired distance L q between the two vehicles can be approximated as:

[0048]

[0049] Wherein, L is the actual distance between the vehicle and the preceding vehicle, v f is the current speed of the preceding vehicle, v x is the current speed of the vehicle, and a max is the maximum acceleration of the preceding vehicle during following.

[0050] Wherein, the rate of change of the deviation ε 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] Taking the derivative of formula (4), we can get:

[0055]

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

[0057]

[0058] Wherein, is the boundary value of the change 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), and the expression of the function sat0(S) is specifically as follows:

[0059]

[0060] Therefore, the rate of convergence function is:

[0061]

[0062] Where k is the exponential coefficient and ε is the constant velocity coefficient.

[0063] By combining equations (5) and (8), the desired acceleration a after sliding mode control adjustment can be obtained. c for:

[0064]

[0065] Among them, a f This represents the current acceleration of the vehicle in front.

[0066] (2) The desired acceleration a x The difference a from the current acceleration a(t) of the vehicle x -a is the current deviation e(t). Based on the PID control, the change in the vehicle's current acceleration Δa(t) is output to control the vehicle's stable output acceleration change, so that the vehicle's acceleration reaches the desired acceleration a. x ;

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

[0068]

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

[0070] This invention defines a sliding surface and a reaching rate to output input parameters (current vehicle speed v). f The current speed of this vehicle, v x And the actual distance L between this vehicle and the vehicle in front, and the maximum acceleration a of the vehicle in front during the following process. max The desired acceleration a that varies reasonably near the sliding surface. x It can ensure a safe stopping distance and achieve comfortable braking with appropriate deceleration under deceleration conditions. Furthermore, by controlling the change in stable output acceleration of the vehicle through PID control, the stability of vehicle control is improved.

[0071] Figure 2 This is a schematic diagram of the acceleration control system provided in an embodiment of the present invention. For ease of explanation, only the parts related to the embodiment of the present invention are shown. The system includes:

[0072] The input unit, the acquisition unit, the processor and the execution mechanism are arranged in the vehicle, the acquisition unit and the input unit are connected with the processor in communication, the processor and the execution mechanism are connected in communication, the expected acceleration calculation model and the PID control model are integrated on the processor,

[0073] The input unit is used for inputting the set comfortable following vehicle acceleration a c during braking q The expected acceleration calculation model is used for inputting the set proportional coefficient K P , the integral coefficient K I and the differential coefficient K D The PID control model is inputted.

[0074] The acquisition unit is used for acquiring the current vehicle speed v f , the acceleration a f , the current vehicle speed v x of the vehicle and the actual distance L between the vehicle and the front vehicle, and sending the actual distance L to the expected acceleration calculation model, the expected acceleration calculation model outputs the expected acceleration a x required by the change of the input parameter near the sliding surface, the expected acceleration a x is inputted into the PID control model as the current deviation e(t) together with the difference a x -a between the current acceleration a(t) of the vehicle, the PID control model outputs the current acceleration change amount Δa(t), the acceleration change amount Δa(t) is sent to the execution mechanism, the execution mechanism converts the acceleration change amount Δa(t) into the braking force or the driving force to adjust the vehicle speed, controls the change amount of the output acceleration of the vehicle to make the acceleration of the vehicle reach the expected acceleration a x .

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

[0076]

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

[0078]

[0079] Wherein, is the change interval boundary value.

[0080] In the embodiment of the application, the PID control model is specifically as follows:

[0081]

[0082] the desired acceleration a x the difference a x -a as the current deviation e(t), input the PID control model, and the PID control model outputs the current acceleration change amount Δa(t).

[0083] The present application defines the sliding surface and the approach rate, and outputs the desired acceleration a x which can ensure the safe stopping distance and achieve comfortable braking with appropriate deceleration under deceleration conditions, and further improves the stability of vehicle control by the PID control of the stable output acceleration change amount of the vehicle.

[0084] In another embodiment of the present application, a vehicle is also provided, which integrates the above-mentioned acceleration control system, and when the vehicle is in the unmanned state or the automatic driving state, the current desired acceleration of the vehicle is determined by the acceleration control system, and the vehicle is controlled to change from the current acceleration to the desired acceleration stably, which can ensure the safe stopping distance and achieve comfortable braking with appropriate deceleration under deceleration conditions.

[0085] Other embodiments of the present application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. The application is intended to cover any variations, uses or adaptations of the application following, in general, the principles of the application and including such departures from the present disclosure as come within known or customary practice in the art to which the application pertains. The specification and examples are to be regarded as illustrative only.

[0086] It should be understood that the application is not limited to the precise construction and methods described above and shown in the drawings, and various modifications and changes can be made without departing from the scope thereof. The scope of the application is limited only by the claims that follow.

Claims

1. An acceleration control method, characterized in that, The method is as follows: (1) Real-time collection of the current vehicle speed v f acceleration a f The current speed of this vehicle, v x Given the actual distance L between this vehicle and the vehicle in front, determine the desired forward acceleration a required for the input parameters to change near the sliding surface. x ; (2) The desired acceleration a x The difference a from the current acceleration a(t) of the vehicle x -a is the current deviation e(t), and the PID control outputs the change in the vehicle's current acceleration Δa(t) to make the vehicle's acceleration reach the desired acceleration a. x ; Expected forward acceleration a x The specific calculation formula is as follows: Among them, a c To set the comfortable following acceleration during braking, a max The maximum acceleration of the vehicle in front during the following process is given by S, where S is the set sliding surface, S = C·ε + ε′, C is the sliding surface coefficient, and ε is the difference between the actual distance L and the desired distance L between the vehicle and the vehicle in front. q The deviation is ε′, which is the rate of change of the deviation ε. The specific formula for calculating the function sat0(S) is as follows: in, These are the boundary values ​​of the variation range; The actual distance L between the two workshops and the expected distance L q The specific deviation ε is as follows: Where L is the actual distance between this vehicle and the vehicle in front, v f v represents the current speed of the vehicle in front. x a is the current speed of this vehicle. max L represents the maximum acceleration of the vehicle in front during the following process. min This is the minimum following distance.

2. The acceleration control method as described in claim 1, characterized in that, The formula for calculating the change in current acceleration Δa(t) is as follows: Among them, K P K is the proportionality coefficient. I K is the integral coefficient. D is the differential coefficient.

3. An acceleration control system, characterized in that, The system includes: The system includes an input unit, a data acquisition unit, a processor, and an actuator. The data acquisition unit and the input unit are communicatively connected to the processor, and the processor is communicatively connected to the actuator. The processor integrates a desired acceleration calculation model and a PID control model. The input unit is used to input the set comfort following acceleration a during braking. c Expected vehicle distance L q Input the desired acceleration calculation model and set the proportional coefficient K. P Integral coefficient K I Differential coefficient K D Input the PID control model; The data acquisition unit is used to collect the current vehicle speed v in real time. f acceleration a f The current speed of this vehicle, v x The actual distance L between this vehicle and the vehicle in front is calculated and sent to the desired acceleration calculation model; The desired acceleration a is required for the input parameters of the desired acceleration calculation model to change near the sliding surface. x ; The desired 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), which is 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. The specific model for calculating the desired acceleration is as follows: Where S is the sliding surface, S=C·ε+ε′, C is the sliding surface coefficient, and ε is the actual distance L between the current vehicle and the vehicle in front, and the expected distance L. q The deviation is ε′, which is the rate of change of the deviation ε. The specific formula for calculating the function sat0(S) is as follows: in, These are the boundary values ​​of the variation range; The actual distance L between the two workshops and the expected distance L q The specific deviation ε is as follows: Where L is the actual distance between this vehicle and the vehicle in front, v f v represents the current speed of the vehicle in front. x a is the current speed of this vehicle. max L represents the maximum acceleration of the vehicle in front during the following process. min This is the minimum following distance.

4. The acceleration control system as described in claim 3, characterized in that, The PID control model is as follows: The desired 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), which is input into the PID control model. The PID control model outputs the current acceleration change Δa(t).

5. A vehicle, characterized in that, The vehicle is equipped with an acceleration control system as described in any one of claims 3 to 4. When the vehicle is in an unmanned or autonomous driving state, the acceleration control system determines the current desired acceleration of the vehicle and controls the vehicle to change from the current acceleration to the desired acceleration in a stable manner.

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