CN117922554A - Method and system for controlling emergency collision avoidance stability of automatic driving vehicle - Google Patents
Method and system for controlling emergency collision avoidance stability of automatic driving vehicle Download PDFInfo
- Publication number
- CN117922554A CN117922554A CN202410049252.7A CN202410049252A CN117922554A CN 117922554 A CN117922554 A CN 117922554A CN 202410049252 A CN202410049252 A CN 202410049252A CN 117922554 A CN117922554 A CN 117922554A
- Authority
- CN
- China
- Prior art keywords
- vehicle
- collision avoidance
- axis
- centroid
- emergency collision
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000000034 method Methods 0.000 title claims abstract description 49
- 230000008569 process Effects 0.000 claims abstract description 18
- 238000001824 photoionisation detection Methods 0.000 claims description 29
- 230000001133 acceleration Effects 0.000 claims description 15
- 238000006073 displacement reaction Methods 0.000 claims description 14
- 230000001276 controlling effect Effects 0.000 claims description 11
- 238000012937 correction Methods 0.000 claims description 5
- 230000001105 regulatory effect Effects 0.000 claims description 5
- 238000013459 approach Methods 0.000 claims description 4
- 230000009977 dual effect Effects 0.000 claims description 4
- 239000011159 matrix material Substances 0.000 description 4
- 238000005457 optimization Methods 0.000 description 4
- 238000004364 calculation method Methods 0.000 description 3
- 230000008859 change Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 238000013461 design Methods 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 238000005096 rolling process Methods 0.000 description 2
- 239000000725 suspension Substances 0.000 description 2
- 206010039203 Road traffic accident Diseases 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000011217 control strategy Methods 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000004044 response Effects 0.000 description 1
Landscapes
- Steering Control In Accordance With Driving Conditions (AREA)
Abstract
The invention discloses a method and a system for controlling the emergency collision avoidance stability of an automatic driving vehicle, wherein the method comprises the following steps: determining the maximum stable vehicle speed of the vehicle in the emergency collision avoidance process based on a two-degree-of-freedom vehicle dynamics model; judging whether the actual vehicle speed exceeds the maximum stable vehicle speed, if so, actively braking the vehicle; if not, the vehicle tracks the predetermined trajectory through 2WS or 4 WS. The invention can effectively improve the path tracking performance and the running stability of the automatic driving vehicle in the emergency collision avoidance process, and has high control precision.
Description
Technical Field
The invention relates to the field of vehicle control, in particular to a method and a system for controlling emergency collision avoidance stability of an automatic driving vehicle.
Background
With the rapid development and progress of the social economy and the automobile industry, the importance of the automobile safety problem is continuously increased. In the last decades, in order to improve the active safety of intelligent vehicles, pre-braking, four-wheel steering (4 WS), direct yaw moment control (DYC) and other modes are generally adopted, and these systems greatly reduce the occurrence of road traffic accidents.
In order to improve the lateral stability of a vehicle during collision avoidance, in the prior art, a stability controller generally keeps a sideslip angle within a safety threshold, a driver can control a turn to be stable through steering actions, and further improve the stability of the vehicle, wherein direct yaw moment control (DYC) is the basis of a vehicle stability control system, and main calculation methods of the direct yaw moment control (DYC) are linear secondary regulators, fuzzy control, fuzzy PID control and sliding mode control.
Aiming at road adhesion coefficient and speed change under different road conditions, a fuzzy self-adaptive PID strategy for vehicle safety and stability control adjusts PID parameters by adopting fuzzy control so as to adapt to different working conditions, and has better robustness; however, the fuzzy rule and membership function have higher requirements and the control accuracy thereof has larger change. The prior art of controlling the motor driving system in the wheel realizes the smooth adjustment of the longitudinal and transverse movement of the vehicle under various transportation conditions; the data fusion technology is adopted to correct the measured data so as to improve the control precision and the response, synchronously estimate the sideslip angle and the yaw rate, and then, based on the active yaw moment obtained by calculation, a feedforward-feedback control system is constructed so as to improve the maneuverability and the stability of the vehicle; however, it does not take into account the influence of different road attachment coefficients on the control system.
Therefore, in order to solve the above problems, there is a need for a method and a system for controlling the emergency collision avoidance stability of an automatic driving vehicle, which can fully consider various influencing factors, effectively improve the path tracking performance and the driving stability of the automatic driving vehicle in the emergency collision avoidance process, and have high control precision.
Disclosure of Invention
In view of the above, the invention aims to overcome the defects in the prior art, and provides the method and the system for controlling the emergency collision avoidance stability of the automatic driving vehicle, which can fully consider various influencing factors, effectively improve the path tracking performance and the driving stability of the automatic driving vehicle in the emergency collision avoidance process and have high control precision.
The invention relates to a method for controlling the emergency collision avoidance stability of an automatic driving vehicle, which comprises the following steps:
Determining the maximum stable vehicle speed of the vehicle in the emergency collision avoidance process based on a two-degree-of-freedom vehicle dynamics model;
Judging whether the actual vehicle speed exceeds the maximum stable vehicle speed, if so, actively braking the vehicle; if not, the vehicle tracks the predetermined trajectory through 2WS or 4 WS.
Further, the two-degree-of-freedom vehicle dynamics model includes a lateral motion equation and a yaw motion equation;
The lateral motion equation is:
wherein m is the vehicle mass, V is the vehicle speed, The mass center cornering angle speed is represented by r, the yaw rate, C f, the cornering stiffness of the front tire, delta f, the front wheel corner, l f, the distance from the mass center to the front axle, beta, the mass center cornering angle, and C r, the cornering stiffness of the rear tire;
the yaw motion equation is as follows:
wherein, I z is the yaw moment of inertia of the vehicle about the Z axis; is yaw acceleration; l r is the distance from the centroid to the rear axis; the straight line of the vehicle running direction is taken as an X axis, the straight line perpendicular to the X axis is taken as a Y axis in the horizontal plane of the vehicle, and the straight line perpendicular to the plane formed by the X axis and the Y axis is taken as a Z axis.
Further, a maximum stable vehicle speed V r of the vehicle in the emergency collision avoidance process is determined according to the following formula:
wherein m is the mass of the vehicle; l is the sum of the distance from the centroid to the rear axis and the distance from the centroid to the front axis; mu is the road adhesion coefficient; l f is the distance from the centroid to the front axis; h is a front steering correction coefficient; r is road curvature; Δy c is the relative lateral displacement.
Further, actively braking the vehicle, comprising: the control of longitudinal movement is realized by adopting double PIDs; wherein the dual PID includes a first PID and a second PID;
The first PID controls the position error e 1 to adjust the speed; wherein the error e 1 is the difference between the lateral displacements of the desired path and the actual path;
the second PID controls the speed error e 2 to regulate the acceleration; the error e 2 is the difference between the set speed and the actual vehicle speed; the set speed is the sum of the desired vehicle speed and the regulated vehicle speed output by the first PID control.
Further, after the vehicle is actively braked, the method comprises the following steps: four-wheel steering control;
The four-wheel steering control adopts proportional control; wherein, the steering angle of the front and rear wheels is adjusted according to the mode of the proportion coefficient; the proportionality coefficient of the rear wheel steering angle delta r and the front wheel steering angle delta f in steady state steering is K ff;
The scaling factor is determined to be K ff according to the following formula:
where l is the sum of the distance from the centroid to the rear axis and the distance from the centroid to the front axis.
Further, after the vehicle is actively braked, the method comprises the following steps: direct yaw moment control;
And the direct yaw moment control adopts a sliding mode variable structure to control the active yaw moment.
Further, the active yaw moment is controlled by adopting a sliding mode variable structure, and the method specifically comprises the following steps: determining a control amount of the additional yaw moment through deviation of the centroid side deviation angle reference value and the yaw rate reference value;
Wherein the control amount Δm of the additional yaw moment is determined according to the following formula:
Wherein, beta is the centroid slip angle; r is yaw rate; epsilon is the boundary layer thickness; s is a sliding surface; sgn(s) is a sign function, when s is greater than 0, sgn(s) =1, when s is equal to 0, sgn(s) =0, when s is less than 0, sgn(s) = -1; k is an approach rate index; The yaw acceleration corresponding to the yaw-rate reference value r ref.
Further, the saturation function sat(s) is used to replace the sign function sgn(s);
wherein,
Δs is the sliding surface variation; delta is the given boundary layer thickness.
An automatic driving vehicle emergency collision avoidance stability control system comprises a vehicle speed determining unit and a stability control unit;
The vehicle speed determining unit is used for determining the maximum stable vehicle speed of the vehicle in the emergency collision avoidance process based on the two-degree-of-freedom vehicle dynamics model;
The stability control unit is used for judging whether the actual vehicle speed exceeds the maximum stability vehicle speed, and if yes, the vehicle is actively braked; if not, the vehicle tracks the predetermined trajectory through 2WS or 4 WS.
Further, a maximum stable vehicle speed V r of the vehicle in the emergency collision avoidance process is determined according to the following formula:
wherein m is the mass of the vehicle; l is the sum of the distance from the centroid to the rear axis and the distance from the centroid to the front axis; mu is the road adhesion coefficient; l f is the distance from the centroid to the front axis; h is a front steering correction coefficient; r is road curvature; Δy c is the relative lateral displacement.
The beneficial effects of the invention are as follows: the invention discloses a method and a system for controlling the emergency collision avoidance stability of an automatic driving vehicle, which are used for determining the maximum stable vehicle speed in the emergency collision avoidance process based on a two-degree-of-freedom vehicle dynamics model, and actively braking the vehicle if the actual vehicle speed exceeds the maximum stable vehicle speed; secondly, four-wheel steering control and direct yaw moment control are adopted to further improve the stability of the vehicle in the collision avoidance process. The invention can fully consider various influencing factors, effectively improve the path tracking performance and the running stability of the automatic driving vehicle in the emergency collision avoidance process, and has high control precision.
Drawings
The invention is further described below with reference to the accompanying drawings and examples:
FIG. 1 is a schematic diagram of the stability control principle of the present invention;
FIG. 2 is a schematic representation of a vehicle dynamics model of the present invention;
FIG. 3 is a schematic diagram of the control principle of the dual PID controller according to the invention;
FIG. 4 is a schematic diagram of various control strategies according to the present invention.
Detailed Description
The invention is further described with reference to the accompanying drawings, in which:
The invention relates to a method for controlling the emergency collision avoidance stability of an automatic driving vehicle, which comprises the following steps:
Determining the maximum stable vehicle speed of the vehicle in the emergency collision avoidance process based on a two-degree-of-freedom vehicle dynamics model;
judging whether the actual vehicle speed exceeds the maximum stable vehicle speed, if so, actively braking the vehicle through an active brake control system; if not, the vehicle tracks the predetermined trajectory through 2WS or 4 WS. The 2WS is an existing front wheel steering control technology, and the 4WS is an existing four wheel steering control technology, which will not be described herein.
In this embodiment, in the path planning, collision avoidance path planning is a precondition for implementing collision avoidance. In order to generate a smooth and continuous path, the invention selects a fifth order polynomial as the collision avoidance path planning algorithm. The expression is as follows:
Wherein: y is the lateral displacement of the vehicle; x is the longitudinal displacement of the vehicle; a is the lane width; and b is the longitudinal movement distance of the vehicle before and after lane changing.
Vehicle dynamics models are classified into various types according to different research emphasis. The main research objective of the invention is to make the vehicle track the expected track stably and efficiently, which belongs to the problem of vehicle steering stability. In the invention, a 2-degree-of-freedom vehicle dynamics model is shown in figure 2, and in the dynamics modeling process, the following assumption is made that (1) the vehicle and the suspension are assumed to be rigid bodies, and the suspension dynamics is ignored; (2) Assuming that the vehicle adopts front wheel steering, the steering angles of the two wheels are the same; (3) It is assumed that the wheels of each axle are combined into one wheel along the centerline of the vehicle.
Equations of lateral and yaw motion can be expressed as:
The front-rear wheel camber angle can be expressed as:
considering that the steering angle and the tire slip angle are generally small angles when the vehicle is traveling at a high speed, the lateral force generated by the tire is proportional to the tire slip angle, and then the equations of lateral motion and yaw motion can be expressed as:
wherein m is the vehicle mass, V is the vehicle speed, The mass center cornering angle speed is represented by r, the yaw rate, C f, the cornering stiffness of the front tire, delta f, the front wheel corner, l f, the distance from the mass center to the front axle, beta, the mass center cornering angle, and C r, the cornering stiffness of the rear tire; i z is the yaw moment of inertia of the vehicle about the Z axis; /(I)Is yaw acceleration; l r is the distance from the centroid to the rear axis; the straight line of the vehicle running direction is taken as an X axis, the straight line perpendicular to the X axis is taken as a Y axis in the horizontal plane of the vehicle, and the straight line perpendicular to the plane formed by the X axis and the Y axis is taken as a Z axis.
In this embodiment, the desired vehicle speed through the road is found by calculating the relationship between the lateral deviation from the heading center and the vehicle speed to obtain the minimum radius of curvature and the minimum lateral deviation through the road at the time of fixing the road surface adhesion coefficient. When the vehicle speed is higher than the expected speed (namely, the maximum stable speed), the vehicle is controlled by the double PID to drive at the expected speed so as to ensure the safety of the vehicle.
The transverse deviation of the actual displacement and the tracking displacement of the vehicle has a certain relation with the vehicle speed, and the corresponding safe vehicle speed under the maximum transverse deviation can be solved on the premise of giving the curvature and the attachment coefficient of the road. Assuming that the vehicle speed is constant, equation (3) may be expressed as:
wherein y c is a lateral displacement, and ψ is a yaw angle;
assuming that the vehicle is traveling at a constant speed on a curve with a curvature R, the equation can be expressed as:
Wherein Δy c is the relative lateral displacement and Δψ is the relative yaw angle;
constructing a state equation by using the relative variables:
wherein,
C 11＝-V,c12＝a11V,c32＝-V2+a31 V by calculation, the relation of the desired vehicle speed (maximum steady vehicle speed V r) is as follows:
Wherein m is the mass of the vehicle; l is the sum of the distance from the centroid to the rear axis and the distance from the centroid to the front axis; mu is the road adhesion coefficient; l f is the distance from the centroid to the front axis; h is a front steering correction coefficient, h=4.5×10 -2; r is road curvature; Δy c is the relative lateral displacement.
According to the above formula, when the vehicle adheres to the fixed road surface by the coefficient μ, the desired vehicle speed V r through the road can be found from the radius of curvature R and the lateral deviation Δy c of the road.
The maximum lateral deviation of the present invention is 0.555m, and the expected speed is 24.7km/h when the road surface is a low adhesion road surface (u=0.3); when the road surface is a medium adhesion road surface (u=0.6), the expected speed is 35km/h; when it is a high adhesion road surface (u=1.0), the desired speed is 45km/h; assume a maximum lateral deviation of 0.55m. According to the formula, when the vehicle is in double-lane-change emergency collision avoidance, the safe vehicle speed under the low, medium and high attached roads is 24.7km/h,35km/h and 45km/h respectively.
In this embodiment, actively braking a vehicle includes: the control of longitudinal movement is realized by adopting double PIDs; wherein the dual PID includes a first PID and a second PID;
The first PID controls the position error e 1 to adjust the speed; wherein the error e 1 is the difference between the lateral displacements of the desired path and the actual path;
the second PID controls the speed error e 2 to regulate the acceleration; the error e 2 is the difference between the set speed and the actual vehicle speed; the set speed is the sum of the desired vehicle speed and the regulated vehicle speed output by the first PID control.
Specifically, the control of the longitudinal movement is realized by adopting double PIDs, and the controller is shown in the figure 3, wherein: sr and V r,ar are respectively the expected positions, the expected speeds and the expected accelerations; s, V, a are the actual positions, the actual speeds and the actual accelerations respectively; vd, a d are respectively the regulated speeds, the regulated accelerations.
A first PID controls the position error e 1 to adjust the speed;
The second PID controls the speed error e 2 to adjust the acceleration.
And transmits the torque to the motor drive (brake) through torque distribution.
The present invention controls the driving torque of a vehicle by using an in-wheel motor. And simplifying the permanent magnet brushless direct current motor model into a 2-order system.
Wherein: A target torque calculated for the controller; t m is the output torque of the hub motor; motor characteristic parameter ζ=0.05.
The longitudinal control of the vehicle can be completed by obtaining the driving moment of the vehicle through the acceleration of the vehicle and distributing the driving moment to four wheels. The distribution mode adopts axle load proportion distribution, and the method for determining the estimated values of the front axle load and the rear axle load is as follows:
As known from vehicle kinematics, the driving moments of the four wheels are:
considering the road adhesion coefficient, the driving force is:
Ti＝min(Ti,uFzi) i＝1,2,3,4 (13)
Wherein: h g is the height of the mass center, B is the tread, T i is the driving moment of the left front wheel, the right front wheel, the left rear wheel and the right rear wheel respectively, and R is the limited rolling radius of the tire.
In this embodiment, the 2WS controller herein adopts a Model Predictive Controller (MPC), and the MPC algorithm has the advantages of predictive control and solving the constraint control problem, and is generally applied to the design of a transverse controller. The MPC controller ensures accurate transverse tracking control through real-time rolling optimization of the front wheel steering angle.
The kinetic equation is expressed by a state equation:
Wherein: the state vector x= [ Y, ψ, v y,r]T, the control input u= [ δ f]T, the control output y= [ ψ, Y ] T.
For the problem of nonlinear model predictive control, the requirements on the performance of the controller are high in quick optimization, and particularly in the field of intelligent automobiles with high real-time requirements. To increase the speed of the optimization solution, the nonlinear predictive model is converted to a linear model to reduce complexity and increase the solution speed. The state equation linearization results in a linear motion programming model as follows:
Wherein: is a jacobian matrix relative to state variables and control quantities.
In order to realize faster real-time control of the whole system, the linear motion programming model is discretized to obtain a discretized state equation:
Wherein:
In order to bring the vehicle as close to the target path as possible, the MPC path tracking controller design problem is described as a general optimization problem, the purpose of which is to find the optimal control input vector deltau (k+i|k) to minimize the tracking error between the predicted output and the reference value. Since smart vehicles may encounter abrupt changes in control variables during travel, a slack factor must be added to the objective function. The objective function is therefore:
Wherein N p,Nc represents a prediction time domain and a control time domain respectively, Q, R represents a diagonal weight matrix, Q is a state tracking weight matrix, R is a weight matrix for controlling input change, ε represents a relaxation factor, and ρ represents a relaxation factor weight coefficient.
MPC presents excellent advantages in dealing with multi-constraint problems. Constraints may be added to the system control variables and control increments in each control step of the MPC controller. In path tracking control, the MPC controller may take physical constraints of the vehicle system as constraints and provide future references from predefined paths. The constraint conditions are as follows:
Wherein U max and U min are the maximum value and the minimum value of the control variable respectively, and correspond to the boundary value of the front wheel rotation angle. Δu max and Δu min are the maximum and minimum values of the control increment, respectively, that is, the boundary value of the front wheel steering angle increment.
After the vehicle is actively braked, the method comprises the following steps: four-wheel steering control;
The four-wheel steering control adopts proportional control; wherein, the steering angle of the front and rear wheels is adjusted according to the mode of the proportion coefficient; the proportionality coefficient of the rear wheel steering angle delta r and the front wheel steering angle delta f in steady state steering is K ff;
Wherein delta r＝Kffδf (19)
The scaling factor is determined to be K ff according to the following formula:
where l is the sum of the distance from the centroid to the rear axis and the distance from the centroid to the front axis.
In this embodiment, after the vehicle is actively braked, the method includes: direct yaw moment control;
And the direct yaw moment control adopts a sliding mode variable structure to control the active yaw moment.
Specifically, in order to improve the control stability of the vehicle during running, the active yaw moment is controlled by adopting a sliding mode variable structure. Taking the yaw rate and the centroid side-slip angle in the two-degree-of-freedom dynamic model as expected reference values, and determining the control quantity of the additional yaw moment through the deviation of the centroid side-slip angle reference value and the yaw rate reference value;
When the vehicle is traveling at a constant speed to a steady state, with dβ=0, dr=0, the ideal centroid slip angle and yaw rate of the reference model can be expressed as:
Wherein: vehicle understeer gradient
Since the maximum lateral acceleration achievable by the vehicle is limited by the ground attachment coefficient, the constraints of the ideal centroid slip angle and yaw rate can be expressed as:
Thus, the reference values of the centroid slip angle and the yaw rate can be expressed as:
From the motion equation of the linear two-degree-of-freedom vehicle model, the yaw rate and the centroid slip angle have a certain coupling relation, and a single variable cannot fully reflect the motion state of the vehicle. Therefore, the present invention analyzes the joint control of the yaw rate and the centroid slip angle. First, the sliding surface is defined as:
s＝(r-rref)+λ(β-βref) (23)
By differentiating the two ends:
The invention selects the index approach rate to constrain the trajectory of the system:
wherein: epsilon is the boundary layer thickness and K is the approach rate index.
Adding an additional yaw moment in the formula (4), and combining the formulas (15) and (16) to solve the output variable, namely, the control quantity delta M of the additional yaw moment is as follows:
Wherein, beta is the centroid slip angle; r is yaw rate; s is a sliding surface; sgn(s) is a sign function, when s is greater than 0, sgn(s) =1, when s is equal to 0, sgn(s) =0, when s is less than 0, sgn(s) = -1; The yaw acceleration corresponding to the yaw-rate reference value r ref.
To eliminate buffeting, the saturation function sat(s) is used to replace the sign function sgn(s);
wherein,
Δs is the sliding surface variation; delta is a given boundary layer thickness and can take on a value of 0.05.
Because of the additional active yaw moment, equation (12) can be modified to (28), then the drive moment for the four wheels is:
the invention also relates to an automatic driving vehicle emergency collision avoidance stability control system, which corresponds to the automatic driving vehicle emergency collision avoidance stability control method and can be understood as a system for realizing the method, and the system comprises a vehicle speed determining unit and a stability control unit;
The vehicle speed determining unit is used for determining the maximum stable vehicle speed of the vehicle in the emergency collision avoidance process based on the two-degree-of-freedom vehicle dynamics model;
The stability control unit is used for judging whether the actual vehicle speed exceeds the maximum stability vehicle speed, and if yes, the vehicle is actively braked; if not, the vehicle tracks the predetermined trajectory through 2WS or 4 WS.
The invention provides an objective and scientific method and a system for controlling the stability of emergency collision avoidance, which improve the active safety of an intelligent driving vehicle during high-speed running, avoid accidents through pre-braking control, and further improve the stability of the vehicle during collision avoidance by four-wheel steering control and direct yaw moment control.
Finally, it is noted that the above embodiments are only for illustrating the technical solution of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications and equivalents may be made thereto without departing from the spirit and scope of the technical solution of the present invention, which is intended to be covered by the scope of the claims of the present invention.
Claims (10)
1. A method for controlling the emergency collision avoidance stability of an automatic driving vehicle is characterized by comprising the following steps of: the method comprises the following steps:
Determining the maximum stable vehicle speed of the vehicle in the emergency collision avoidance process based on a two-degree-of-freedom vehicle dynamics model;
Judging whether the actual vehicle speed exceeds the maximum stable vehicle speed, if so, actively braking the vehicle; if not, the vehicle tracks the predetermined trajectory through 2WS or 4 WS.
2. The automatic driving vehicle emergency collision avoidance stability control method according to claim 1, characterized in that: the two-degree-of-freedom vehicle dynamics model comprises a lateral motion equation and a yaw motion equation;
The lateral motion equation is:
wherein m is the vehicle mass, V is the vehicle speed, The mass center cornering angle speed is represented by r, the yaw rate, C f, the cornering stiffness of the front tire, delta f, the front wheel corner, l f, the distance from the mass center to the front axle, beta, the mass center cornering angle, and C r, the cornering stiffness of the rear tire;
the yaw motion equation is as follows:
wherein, I z is the yaw moment of inertia of the vehicle about the Z axis; is yaw acceleration; l r is the distance from the centroid to the rear axis; the straight line of the vehicle running direction is taken as an X axis, the straight line perpendicular to the X axis is taken as a Y axis in the horizontal plane of the vehicle, and the straight line perpendicular to the plane formed by the X axis and the Y axis is taken as a Z axis.
3. The automatic driving vehicle emergency collision avoidance stability control method according to claim 1, characterized in that: the maximum stable vehicle speed V r of the vehicle in the process of emergency collision avoidance is determined according to the following formula:
wherein m is the mass of the vehicle; l is the sum of the distance from the centroid to the rear axis and the distance from the centroid to the front axis; mu is the road adhesion coefficient; l f is the distance from the centroid to the front axis; h is a front steering correction coefficient; r is road curvature; Δy c is the relative lateral displacement.
4. The automatic driving vehicle emergency collision avoidance stability control method according to claim 1, characterized in that: actively braking the vehicle, comprising: the control of longitudinal movement is realized by adopting double PIDs; wherein the dual PID includes a first PID and a second PID;
The first PID controls the position error e 1 to adjust the speed; wherein the error e 1 is the difference between the lateral displacements of the desired path and the actual path;
the second PID controls the speed error e 2 to regulate the acceleration; the error e 2 is the difference between the set speed and the actual vehicle speed; the set speed is the sum of the desired vehicle speed and the regulated vehicle speed output by the first PID control.
5. The automatic driving vehicle emergency collision avoidance stability control method according to claim 1, characterized in that: after the vehicle is actively braked, the method comprises the following steps: four-wheel steering control;
The four-wheel steering control adopts proportional control; wherein, the steering angle of the front and rear wheels is adjusted according to the mode of the proportion coefficient; the proportionality coefficient of the rear wheel steering angle delta r and the front wheel steering angle delta f in steady state steering is K ff;
The scaling factor is determined to be K ff according to the following formula:
where l is the sum of the distance from the centroid to the rear axis and the distance from the centroid to the front axis.
6. The automatic driving vehicle emergency collision avoidance stability control method according to claim 1, characterized in that: after the vehicle is actively braked, the method comprises the following steps: direct yaw moment control;
And the direct yaw moment control adopts a sliding mode variable structure to control the active yaw moment.
7. The automatic driving vehicle emergency collision avoidance stability control method according to claim 1, characterized in that: the active yaw moment is controlled by adopting a sliding mode variable structure, and the method specifically comprises the following steps: determining a control amount of the additional yaw moment through deviation of the centroid side deviation angle reference value and the yaw rate reference value;
Wherein the control amount Δm of the additional yaw moment is determined according to the following formula:
Wherein, beta is the centroid slip angle; r is yaw rate; epsilon is the boundary layer thickness; s is a sliding surface; sgn(s) is a sign function, when s is greater than 0, sgn(s) =1, when s is equal to 0, sgn(s) =0, when s is less than 0, sgn(s) = -1; k is an approach rate index; The yaw acceleration corresponding to the yaw-rate reference value r ref.
8. The automatic driving vehicle emergency collision avoidance stability control method according to claim 1, characterized in that: replacing the sign function sgn(s) with a saturation function sat(s);
wherein,
Δs is the sliding surface variation; delta is the given boundary layer thickness.
9. An automatic driving vehicle emergency collision avoidance stability control system, which is characterized in that: comprises a vehicle speed determining unit and a stability control unit;
The vehicle speed determining unit is used for determining the maximum stable vehicle speed of the vehicle in the emergency collision avoidance process based on the two-degree-of-freedom vehicle dynamics model;
The stability control unit is used for judging whether the actual vehicle speed exceeds the maximum stability vehicle speed, and if yes, the vehicle is actively braked; if not, the vehicle tracks the predetermined trajectory through 2WS or 4 WS.
10. The autonomous vehicle emergency collision avoidance stability control system of claim 1, wherein: the maximum stable vehicle speed V r of the vehicle in the process of emergency collision avoidance is determined according to the following formula:
wherein m is the mass of the vehicle; l is the sum of the distance from the centroid to the rear axis and the distance from the centroid to the front axis; mu is the road adhesion coefficient; l f is the distance from the centroid to the front axis; h is a front steering correction coefficient; r is road curvature; Δy c is the relative lateral displacement.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202410049252.7A CN117922554A (en) | 2024-01-12 | 2024-01-12 | Method and system for controlling emergency collision avoidance stability of automatic driving vehicle |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202410049252.7A CN117922554A (en) | 2024-01-12 | 2024-01-12 | Method and system for controlling emergency collision avoidance stability of automatic driving vehicle |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117922554A true CN117922554A (en) | 2024-04-26 |
Family
ID=90750138
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202410049252.7A Pending CN117922554A (en) | 2024-01-12 | 2024-01-12 | Method and system for controlling emergency collision avoidance stability of automatic driving vehicle |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN117922554A (en) |
-
2024
- 2024-01-12 CN CN202410049252.7A patent/CN117922554A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN110356404B (en) | Intelligent driving system with autonomous lane changing function and improved lateral safety | |
| CN109976159A (en) | Intelligent vehicle crosswise joint method based on safely controllable domain | |
| CN111923908A (en) | Stability-fused intelligent automobile path tracking control method | |
| CN109969183A (en) | Bend follow the bus control method based on safely controllable domain | |
| CN108177692A (en) | A kind of differential power-assisted steering of electric wheel drive vehicle and stability control method for coordinating | |
| CN111959500B (en) | Automobile path tracking performance improving method based on tire force distribution | |
| WO2022266824A1 (en) | Steering control method and apparatus | |
| CN113978450B (en) | Anti-roll commercial vehicle path tracking game control method | |
| WO2023138258A1 (en) | Self-learning cooperative control method of active steering and yaw moment | |
| CN113911106A (en) | Commercial vehicle transverse track following and stability cooperative control method based on game theory | |
| CN116552550A (en) | Vehicle track tracking control system based on parameter uncertainty and yaw stability | |
| CN116560371A (en) | Self-adaptive model predictive control-based automatic driving vehicle path tracking method | |
| Li et al. | Adaptive sliding mode control of lateral stability of four wheel hub electric vehicles | |
| CN114312848B (en) | Intelligent driving automobile track planning and tracking control method based on double-layer MPC | |
| CN114148403B (en) | Multi-working-condition stability control method for wire-controlled steering system | |
| JP2003231429A (en) | Action to route of vehicle by measured value of lateral force in consideration of load movement on both sides of vehicle symmetrical with respect to center thereof | |
| CN116834754A (en) | Transverse and longitudinal cooperative control method for self-adaptive speed regulation of automatic driving vehicle | |
| CN116714578A (en) | Vehicle lane changing obstacle avoidance method, system, device and storage medium | |
| CN114435399B (en) | Automatic driving automobile stability path tracking method based on predictive model | |
| CN115933662A (en) | Intelligent automobile trajectory tracking and stability control system and method based on adaptive model prediction control | |
| CN114312847B (en) | Transverse control method and device for automatic driving vehicle | |
| CN117922554A (en) | Method and system for controlling emergency collision avoidance stability of automatic driving vehicle | |
| Li et al. | Path tracking control based on the prediction of tire state stiffness using the optimized steering sequence | |
| CN114896694A (en) | Path tracking control method based on two-point preview | |
| CN114148411A (en) | Drift control method of wheel type unmanned platform |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |