Research On Path Planning Of Smooth Avoiding Obstacle And Trajectory Tracking For Manipulators

Manipulators have a wide range of applications in the field of human social production.However,the level of automation and intelligence of manipulators is low at present.Manipulators need human participation to complete the specified tasks,which not only restricts the application scope of manipulators,but also reduces the safety of production processes.In order to overcome the above two problems,it has important significance to explore a universal smooth obstacle avoidance path planning method for manipulators.Potential energy functions were introduced into probabilistic roadmap method(PRM)to study potential energy-PRM algorithm with low time complexity and high planning quality;on this basis,the potential energy functions about joint vectors of manipulator links were established;a safe path detection method of manipulators under different joint vectors was studied;potential energy-PRM algorithm was applied to the obstacle avoidance planning of manipulators,and an obstacle avoidance path planning method with strong applicability,high planning efficiency and high planning quality was explored.In order to enhance the movement performance of obstacle avoidance processes for manipulators,the problem of poor optimization quality of MOPSO was tried to overcome by studying external archives self-searching strategy and diversity maintaining strategy;an improved MOPSO was used to optimize the obtained obstacle avoidance nodes,and the smooth obstacle avoidance trajectory of manipulators with high execution efficiency,low energy consumption and jerk was explored.In order to make manipulators track obstacle avoidance curves,fuzzy equivalent-terminal sliding mode control of manipulators was studied by designing the equivalent term and fuzzy switching term,and a trajectory tracking control method of manipulators with low chattering and excellent control effect was explored.The main research work and achievements of this paper are as follows.1)The obstacle avoidance path planning of manipulators was studied.Aiming at the problem that PRM algorithm is difficult to pass through the narrow area between obstacles,which leads to poor quality of planning results,potential energy functions of planning space nodes were constructed;nodes in difficult regions were defined;an adjustment strategy of obstacle space nodes to nodes in difficult regions was studied through position adjustment equation and probability selection equation;then potential energy-PRM algorithm was proposed.Potential energy functions of manipulator links were constructed;the safe path detection method of manipulators was studied,and the application of potential energy-PRM algorithm in obstacle avoidance path planning for manipulators was explored.The simulation results show that the planning performance of the potential energy-PRM algorithm is better than that of PRM,Gaussian sampling PRM and OBPRM,and the obstacle avoidance planning performance of potential energy-PRM algorithm is better than that of PRM,Gaussian sampling PRM and OBPRM;experimental results show that the potential energy PRM algorithm can complete the obstacle avoidance planning task of manipulators;in addition,the performance evaluation index of obstacle avoidance path planning algorithms is also given.2)Trajectory optimization of obstacle avoidance nodes for manipulators was studied.B-splines were used to interpolate the position nodes of joints;the mathematical model of optimization objectives was established;the constraint conditions of joints were analyzed;the optimization quality improvement strategy of MOPSO was studied by disturbing the solutions in external archives and deleting the solutions that are too close to other solutions in objective space;on this basis,an improved MOPSO was used to optimize obstacle avoidance nodes.The simulation results of test functions show that the improved MOPSO can obtain a better quality frontier with less time cost.The simulation results of obstacle avoidance nodes show that the improved MOPSO can obtain smooth obstacle avoidance trajectories with each motion parameter satisfying constraints.In addition,the selection method of the required optimal solution under different working conditions is also given.3)The trajectory tracking of the obstacle avoidance curves of joints was studied.The equivalent item and the fuzzy switching item of trajectory tracking systems for manipulators were designed by using the design method of equivalent sliding mode control law,and fuzzy equivalent-terminal sliding mode control law of the systems was obtained by adding the two terms;on this basis,the stability and finite arrival time of the systems were analyzed;on the premise of stability,the chattering of the systems was tried to reduce by designing fuzzy rules for fuzzy constants in the fuzzy switching term.Simulation results show that the tracking error of equivalence-terminal sliding mode method is reduced by at least 28.95%and 33.33%compared with equivalence-terminal sliding mode method and equivalent sliding mode method,and the chattering phenomenon of control input is lower than that of equivalence-terminal sliding mode method.