Trajectory Tracking And Attitude Control Of The Synchronous Steering High Clearance Sprayer

As a new type of agricultural plant protection machinery,high clearance unmanned sprayer plays an important role in the prevention and control of pests and diseases in agricultural production.Due to its unique steering structure design,the synchronous steering high clearance sprayer has better trafficability and adaptability in paddy fields with complex and changeable environment.Nevertheless,because of its characteristics of large time delay,strong coupling,and high nonlinearity,the existing trajectory tracking control algorithm cannot meet the structural characteristics of this sprayer.At the same time,the attitude controller of this sprayer cannot respond to the target state in time and achieve stable and reliable control.To solve these problems,this paper established the fuzzy adaptive model predictive control algorithm and the sliding mode active disturbance rejection attitude control algorithm based on the kinematic model of the sprayer and carried out the simulation test and field test,respectively.The main researches are listed below:(1)The trajectory tracking model and attitude control model of the sprayer synchronous steering high clearance sprayer were established.Firstly,according to the characteristics of the synchronous steering structure and the Ackerman steering principle,the nonlinear kinematics model of the sprayer is derived and the feasibility of the chain rod constraint structure is proved.Then,the simplified model and attitude control model of the sprayer are established.Finally,the dynamic model of the sprayer was established to analyze the motion characteristics of the synchronous steering structure and verify the reliability of the kinematic model.(2)The fuzzy adaptive model predictive controller of synchronous steering high clearance sprayer is established to improve the response speed and robustness of trajectory tracking.Firstly,based on the structure of the sprayer,the state prediction matrix is established and the trajectory tracking predictive controller is designed.Then,combined with the actual working conditions of the sprayer,the fuzzy rules are designed and the fuzzy adaptive predictive controller is proposed.Finally,in the field test,average tracking errors of linear trajectory,circular trajectory and ’ U ’ shaped trajectory are 0.0442 m,0.0602 m,0.0901 m and 0.0362 m,and the standard deviations are 0.0518 m,0.0882 m,0.0436 m and 0.0515 m,respectively.The test results show that the fuzzy adaptive trajectory tracking prediction control strategy established in this paper can meet the requirements of unmanned navigation operation of the sprayer,and has fast response speed and great robustness ability.(3)The sliding mode active disturbance rejection attitude controller of synchronous steering high clearance sprayer is established.Firstly,the attitude control model of the sprayer is decoupled and transformed into the standard feedback system.Then the state observers are designed to compensate for the total disturbance of the model in real-time and derive the terminal sliding mode control rate.Finally,in the field test,when the target angle is 5°,the stable durations of the front and rear steering angles of the sprayer are 2.97 s and 2.46 s,respectively.When the target angle is 20°,the stable durations of the front and rear steering angles are 4.57 s and 4.86 s,respectively,and the front and rear steering angles of the sprayer also tend to the target angle and are stable.The experimental results show that the sliding mode active disturbance rejection attitude control algorithm can meet the needs of practical application and has good stability.