Robust control of tomato picking robotic arm considering contact constraint
Aiming at the problem of picking damaged fruits by the end effector caused by low positioning accuracy of the robotic arm,a finite time robust control method is designed.Firstly,the mathematical model of the picking robotic arm with frictional resistance and contact constraints was established,and the dimensions were reduced.Then,the tracking error and the contact constraint of the tomato picking robotic arm end position were taken as the control targets,and the terminal sliding surface was designed.Finally,the finite time Robust control law under the contact constraint was designed by using auxiliary parameters,and the angle error and end contact constraint error of the designed tomato picking robotic arm could converge to 0 in finite time that proved by Lyapunov function.The simulation results show that the designed robust control method can stably track the control command within 0.3 s,and the maximum tracking errors of joint rotation angle and contact force are only 0.3° and 0.08 N·m,respectively,which has better rapidity and accuracy.The results of picking tomatoes tests show that the proposed robust control method can achieve a maximum positioning error of only 0.19 cm at the end of the picking arm,and the maximum contact constraint error is only 0.06 N·m.
tomato pickingrobotic armfrictional resistancecontact constraintterminal sliding surfacerobust control
万方数据
维普
