Research On Motion Optimization And Trajectory Tracking Control Of Space Redundant Manipulator

With the continuous development of aerospace technology and the increasing demand for applications,higher requirements have been placed on space robots.Compared with non-redundant manipulators,redundant manipulators have many advantages,such as motion flexibility,avoiding joint displacement limits,and avoiding singularities.They are the hotspots and focuses of space redundants.Among them,kinematics analysis,trajectory planning,and trajectory tracking control are the basis for the research of robotic arm,which is of great significance to this direction.In this paper,the seven-degree-of-freedom redundant manipulator developed by the laboratory is taken as the research object.The kinematics,trajectory optimization and trajectory tracking control of the manipulator are studied under the controlled conditions of the pedestal.The aim is to reverse the redundant manipulator.Kinematics solution,time-jerk optimal trajectory planning and trajectory tracking control provide an effective method.Firstly,the kinematics model of the seven-degree-of-freedom redundant manipulator is established,and the kinematics analysis is carried out.The problem of solving the inverse kinematics of the seven-degree-of-freedom manipulator is studied.Two methods are used to solve the inverse kinematics of the manipulator: the improved scale factor method and the configuration control method.The improved scale factor method modifies the scale factor in the gradient projection method.Compared with the fixed scale factor method and the equalization scale factor method,this method can overcome the joint speed of the fixed-scale factor method when the end speed of the arm is zero.Therefore,the problem of speed shock is easy to occur,and the defect of the joint angular velocity and angular acceleration caused by the gradient vector of the optimization performance index function approaching zero in the equilibrium scale factor method can be compensated.The other is to use the configuration control method to solve the inverse kinematics of the manipulator in some specific space working scenes.This method is used to ensure that the pose matrices and arm angle values remain unchanged at the planning point.Only the position value changes,and the values of the current plan-point is used.The position,pose and arm angle values of the current plan-point are used to calculate the corresponding values of the next planning point.By iterative calculation,the inverse kinematics solution of all plan-point s can be obtained.The simulation and experimental results show that the proposed methods are effective.Secondly,aiming at the optimal trajectory planning problem of the seven-degree-of-freedom redundant manipulator,this paper proposes an Augmented Lagrangian Multiplier-Compressed Particle Swarm Optimization algorithm based on the advantages of the Augmented Lagrangian Multiplier method and the Compressed Particle Swarm Optimization algorithm.The time-jerk optimal trajectory planning is studied.In this algorithm,on the one hand,by saving and passing the best particles obtained in each search process to the next generation,the optimal values can be retained generation by generation;on the other hand,random initialization generates new other particles to avoid falling into the local maximum.excellent.The time-jerk optimal trajectory planning for the circular and linear trajectory motion of the manipulator is simulated and experimentally verified by this algorithm,and the simulation based on the Sequence Quadratic Programming algorithm,the interior penalty function method and the Compressed Particle Swarm Optimization algorithm.Compared with the experimental results,the effectiveness of the proposed algorithm is verified.Finally,for the most common circular and linear trajectories in the manipulator motion planning task,this paper proposes a high-precision trajectory tracking control study based on the PD and integral sliding mode control method.According to the difference between the circular and straight line planning trajectories,different trajectory tracking control methods are proposed.In the tracking trajectory of the circle,a variable integral sliding mode PD robust control algorithm is proposed.According to the different weighting coefficients in the previously set optimization objective function,the obtained optimized trajectory is divided into low speed and high speed.The PD control parameters are unchanged and then the two types of trajectories are tracked by different integral sliding mode control parameters.The experimental results verify that the proposed algorithm can make the circular trajectory tracking accuracy compared with the results obtained by simply applying the PD control method to the tracking trajectory of the planned trajectory increase by 10%-69.42%.When tracking the linear optimization trajectory,the same integral sliding mode PD robust control parameters are used.After experimental verification,compared with the results obtained by the PD control method,the proposed algorithm can improve the control accuracy by 13.6%-56.7%.