Research On Inertia And Friction Parameter Identification And Compensation Of 6-DOF Serial Robots

The presence of joint friction is an important factor causing the deterioration of the robot servo system.When the industrial robot moves along the trajectory, friction inevitably lead to positional error of the end effector.To reduce the effect of friction on the robot control system, the robot control system must be compensated on the friction torque.In this paper,we research on the identification and compensation based on friction parameters and inertial parameter. And the research of friction is based on the 6-DOF serial robots.This dissertation focuses on the following work:First of all, this paper begins with an introduction of the resreach on the accuracy of the robot. And the methods of identification are introduced on the inertial parameters and friction parameters of the robot.Friction compensation methods are analyzed the advantages and disadvantages.Secondly,based on the latest research achievements on friction modeling, four stages are analyzed when accelerates from zero to sliding at low speed,then the formation mechanisms of the four periods of friction are analyzed.Several important features on dynamic characteristics of friction are introduced in this paper, such as the variability of static friction, pre-sliding displacement, friction memory and creeping phenomenon of friction. Theory and methods which are used in this paper are analyzed and selected.Then, the kinetic modeling of friction is set using Lagrangian mechanics method based on the characteristics of 6-DOF serial robots. The end of link is simplified as two linkage whose track moving rely on rotating wrist joint agency. Some softwares are used to build three-dimensional models in the paper. And the three-dimensional models can be used to identify the inertial parameter of the 6-DOF serial robots. All the parameters of Stribeck friction model is identified based on Genetic Algorithm, and all simulations are using the MATLAB.At last, the transfer function is established based on the six degrees of freedom robot. The Compensation Coulomb friction and viscous friction of Coulomb are based on the second-order transfer function. The simulation is used to the analytical work of the servo system with LuGre friction model.The compensations of PD control after friction compensation to reduce the impact caused by friction.