Research On Attitude Control Of All-terrain Vehicle Based On Series Active Suspension

As vehicle drives in rugged terrain to carry out natural resource’s exploration,military attack,search and rescue,the center of gravity of traditional vehicle will shift and unable to maintain a stable body posture,affecting the accuracy of fieldwork and even causing vehicle rollover.However,the vehicle equipped with active suspension system can realize real-time control the attitude of the body by terrain information to improve the stability and safety.The series active suspension is one of the limited bandwidth active suspensions.Compared to the parallel and hybrid type active suspensions,the actuator of series active suspension is equipped with the shock absorber and its structure is simpler,cost of design is lower,range of attitude adjustment is wider.As well as the performance is no less than full active suspension.According to the analysis above,this paper combines the National Natural Science Foundation of China and the Jilin Province Science and Technology Development Plan project.Based on theoretical research,model building,algorithm optimization,and controller design,with the goal of improving the attitude control of the series active suspension in unstructured terrain,an All-Terrain Vehicle(ATV)based on a series active suspension system is designed.And the following research is carried out.For the problems about difficulty to get the experimental vehicle with active suspension and inaccurate simulation,the prototype of the ATV is designed.First,the general layout of the all-terrain vehicle with attitude control is determined,and the structure of the attitude control system based on the series active suspension is designed.The performance of electric servo actuators and shock absorbers is analyzed.The principle of attitude control of the series active suspension is expounded;secondly,the driving system is designed to drive the vehicle forward,backwards,differential steer and parking brake.Then,the electronic control system is designed to analyze and determine the control system plan to run the subsequent algorithm in real time,the sensor system is designed to perceive the status of the vehicle,and the CAN bus is used to realize the information communication.Finally,the vehicle parameters are calibrated,unstructured terrain is built to lay the foundation for subsequent attitude control research and verification.In order to control the attitude of ATV,the dynamic model is established.First,the kinematics and dynamics of the all-terrain vehicle is analyzed.The motion equations is established.The modeling method about the electric servo actuator speed control of the series active suspension on the basis of the traditional active suspension force control is analyzed by introducing the second-order low-pass filter.The full vehicle dynamic model is established.Secondly,the three road models are designed to verify the simulation performance of attitude controller.Then a terrain estimation algorithm based on the dynamics model and sensor fusion is designed to estimate the road elevation information in real time.Finally,the LQR controller for attitude adjustment is designed,and the performance has the vertical acceleration of the body,the vertical displacement of the body,the pitch angle and the roll angle.And to preliminarily verify the accuracy of the dynamic model and terrain estimation model and the effectiveness of attitude control by test.Due to the problem of insufficient model accuracy and constraints of actuators,the mechanism of model predictive control about model description and constraint control is analyzed,predictive equations based on the ATV vehicle dynamics model is derived,an optimized objective function with constraints is established,and solves the quadratic programming problem,designs the MPC attitude controller based on the series active suspension.Meanwhile,in order to get rid of the complex problems of dynamic modeling,the principle of fuzzy control is analyzed,the body attitude is decoupled.Then combines the PID algorithm,the system output and PID parameters is fuzzyed,uses fuzzy rules for fuzzy reasoning to design Fuzzy-PID controller for multi-input and multi-output of ATV.Finally,after solving the problems of model modeling,accuracy and actuator constraints,the two control strategies designed is verified significantly improve the attitude stability and comfort of the all-terrain vehicle by simulations and tests.