Research On Motion Control And Trajectory Planning Algorithm For Mobile Manipulator

In today’s life and production, mobile manipulator plays an increasingly important roleand it also causes widespread research scholars’ concern at home and abroad. The researchmainly focuses on the mobile manipulator motion planning and control, and trajectory planningis the basis for manipulator trajectory control and it has great significance, especially in theaspects of smooth, operating efficiency, operating accuracy and energy consumption. Thispaper considers both of the kinematic and the operating time constraints, and takes the optimaloperating time, the continuity of the joint displacement, velocity, acceleration trajectory curveas the optimization objectives. The research focuses on the manipulator motion control andtrajectory planning, and the main work is as follows:Firstly, the research state and methods for the mobile manipulator motion control andtrajectory planning are summarized. The various trajectory planning algorithms and itsoptimization method are generalized, and the research background and main contents of thepaper are presented.Secondly, the mobile manipulator mathematical model is set up and analyzed. The mobilemanipulator platform–MT-ARM modular manipulator with four degrees freedom is taken as aresearch object. The D-H(Denavit-Hartenberg) method is used to build up a transformationmatrix to achieve the solution of the kinematics equation, and inversed kinematics equation isobtained through algebraic method. Simulation and experiment results show the correctness ofthe model, which lay a foundation for the trajectory planning; the construction of trajectories injoint space and Cartesian space are established, and equations for line, arc and spline curve inthree-dimensional space are derivated. A manipulator time–optimal trajectory based on splinecurve is proposed. The constraints also include the joint velocity, acceleration, jerk and torques,and the spline curve is used to interpolate the joint trajectory nodes sequence for location-time.The time–optimal trajectory planning problem is converted to solving nonlinear constrainedoptimization problem.Thirdly, a manipulator trajectory optimization method based on genetic algorithm isproposed. The execute time, spatial distance and trajectory length are taken as optimizationswith joint velocity, acceleration and torques constrains. In the environment with or withoutobstacles, the proposed method is verified through simulation experiments, the results showthat the constraints are met and the trajectory velocity and acceleration curves are smooth andcontinuous; in order to improve the smoothness of the joint trajectory, the integral of the jerk’ssquare is taken as the optimization. The cubic spline curve is used to fit the joint trajectory, theresults show that the joint velocity and acceleration are continuous and jerk is bounded.Finally, the architecture of the MT-ARM system is introduced, and a distributed–centralized independent switch and coordinated control system for scalable, modular mobilemanipulators is proposed, which combines the advantages of distributed systems in stabilityand control accuracy and centralized systems in real–time and operating. According to theexternal perception information, the systems can choose appropriate control methodsindependently; meanwhile, the software for the mobile manipulator control system is designedand the performance is analyzed.