System Design Of Seven Degrees Of Freedom Manipulator With Offsets And Research On Kinematic Calibration Method

With the development of science and technology,robots are gradually used to assist workers in many industries to complete their tasks.Therefore,the robot industry has become an important development strategy in China.Compared with the traditional six-degree-offreedom manipulator,the seven-degree-of-freedom manipulator has redundant degrees of freedom,and can achieve any position within the working space and has infinite solutions.It has high research and application value in the fields of medical equipment,home service and industrial automation.In this thesis,through the analysis of the advantages and disadvantages of the sevendegree-of-freedom manipulators with various configurations,a seven-degree-of-freedom manipulator with shoulder,elbow and wrist offsets is designed.For the maximum load conditions,the arm of the "3+2+2" configuration is used to increase the load capacity at the end of the arm.The forward kinematics modeling and workspace analysis of the manipulator with offsets designed in this thesis are carried out.For the problem that the seven-degree-of-freedom manipulator with offsets has no closed solution,the TRAC-IK solver is used to solve the inverse kinematics,provided an inverse kinematic solution with high success rates and real-time performance for a series manipulator that does not comply with the PIEPER criteria.Aiming at the problem that the traditional robot arm kinematic calibration scheme requires high-precision and high-cost three-dimensional measuring instruments,a scheme of using a monocular camera for the geometric parameter calibration of the manipulator kinematics model is proposed,which mainly includes the internal and external reference calibration and rough identification of the camera.Kinematic parameter identification combined with fine identification,kinematic parameter compensation and comparative experimental analysis.The experimental results show that the kinematic calibration scheme proposed in this thesis can improve the absolute positioning accuracy of the end of the manipulator to some extent.Finally,the seven-degree-of-freedom manipulator with offsets and its hardware and software system is designed.A series of experiments are designed to verify the inverse kinematics accuracy and flexible motion characteristics of the manipulator.It is concluded that the seven-degree-of-freedom manipulator with offsets proposed in this thesis can increase the end load and can flexibly avoid obstacles.