Simulation Study Of Kinematic Characteristics, Identification And Compensation Of The Folding Portable Cutting Manipulator

In the manufacturing process of large hull structures such as aircraft carriers, submarines and all kinds of ships, a large number of various holes with variable angle grooves must be cut, because of the special characteristics of the hull surface, cutting equipment is necessary to be transferred in real time to meet the needs of manufacturing in different position. Therefore,it has very important significance to shorten the gap between our country and the world advanced ship manufacturing technology to develop a portable cutting manipulator which is for improving ship manufacturing technology and improving the ship performance to achieve high efficiency and high precision machined variable angle grooves pass on space complex surface.In this paper, a kind of portable cutting manipulator for high efficiency machining hull curved surface was proposed, and the key problems of kinematic characteristics, identification and compensation were studied based on screw theory. The main contents were as follows:Aiming at the requirements of the portable and high efficiency cutting of various kinds of holes, the degree of freedom and the driving mode of each joint were determined, and the design scheme of folding portable structure was proposed. And the double rotary positioning mechanism and the cutting gun swinging mechanism were analyzed theoretically. On the basis of the double rotating connecting rod size calculated by two bar parameter equation, the projection of the working space in the X-Y plane was analyzed, to ensure the cutting range meets the design requirements.Aiming at the analysis of the kinematics characteristics of the cutting manipulator, the kinematics model and kinematics error model were established. Firstly, the DH modeling method was compared with the screw modeling method, and the screw modeling method was selected. Then, the positive solution of the manipulator was given based on the product of exponential formula, and the inverse kinematics of the manipulator was obtained by solution of the subproblem of the screw theory. At last, the kinematics error model of the end position of the cutting manipulator was established by using the partial differentiation of product of exponential formula based on the linear kinematics error model,.Aiming at high precision cutting of the manipulator, studies on the identification and compensation of kinematics parameters were completed. Firstly, the Jacobi matrix for identification of cutting manipulator was derived; Then, the identifiability of kinematics parameters in error model was analyzed according to the linear correlation between the column vector of Jacobi matrix. And the convergence of the iterative least square method in which was introduced the method of screw coordinate updating used in kinematics parameters identification algorithm was proved based on the Lipschitz continuity of exponential and logarithmic. At last, the off line feed-forward error compensation and the PLS calculation method of the joint kinematics variable compensation value were given based on the compensation principle.In the end, the virtual prototype simulation and numerical simulation were carried out by using Adams and Matlab to simulate the kinematics characteristics, kinematics parameters identification and error compensation of cutting manipulator. Simulation results had showed:The kinematics model of the manipulator was correct and effective; All the kinematics parameters in the error model of cutting manipulator could be identified, and the results were more close to the real value than the other methods; The identification algorithm maintained good robustness in the case of measurement noise; The compensation strategy was feasible through the comparison of the error curve before and after compensation.In this paper,the developed portable cutting manipulator,the analysis of its kinematics characteristic and the studies of identification and compensation of kinematics parameters,providing a theoretical reference and engineering basis for solving high precision cutting problems on the hull surface with various holes.