Error Analysis And Compensation Algorithm For Redundant Robot

With the rapid development of the research technology of manipulator,it has spread in aerospace,medical,industrial,EOD,and other service industries.The manipulator developed in this thesis is a lightweight manipulator with redundant degrees of freedom and will be applied in the field of medical massage.Due to the strict limit of the quality,the rigidity of the manipulator is low,and the geometric error and the flexible deformation error exist.In order to improve its performance,it is necessary to reduce the positioning error of the manipulator by compensation.In order to gain a deeper understanding of the principle of the geometric error of the manipulator and improve its accuracy by compensation,this thesis makes an in-depth study on the geometric error modeling,parameter identification and compensation methods.Firstly,the geometric error model is derived based on the kinematic model,and the correctness of the model is verified by a simulation example.Then,the DH parameters are classified,and the influence degree of various parameters on the positioning accuracy of the manipulator is analyzed.These are instructive to the design of the manipulator.And then the geometric parameters of the manipulator are identified by least square method.Finally,the error compensation method is used to compensate the geometric error of the manipulator,and the validity of the method is verified by simulation.In order to better understand the flexible error of manipulator,in this thesis,the joint flexibility of the manipulator is regarded as a linear spring between the rotor and the connecting rod,and the dynamic model is established.On this basis,the vibration characteristics are analyzed.Then,the flexible error model is established for the flexible joint.The torque caused by the weight of the manipulator to seven joints is deduced based on the concept of force Jacobian matrix.In addition,a reliable method for the identification of the joint stiffness of the manipulator is presented.Finally,a real and reliable compensation strategy is proposed.In the experimental part of this paper,the repeatability experiment of manipulator is carried out first.Then,the identification of the geometric parameters and the identification of the joint stiffness of the manipulator are carried out.On the basis of the identification results,the flexible error compensation and geometric error compensation of the manipulator are carried out by using the compensation strategy.The experimental results show that the error model and compensation strategy proposed in this thesis are effective in reducing the positioning error and improving the accuracy of the manipulator.The compensation method is also suitable for the compensation of other degrees of freedom manipulator.