In this paper, a space climbing robot based on Delta parallel mechanism is taken as the research object, its pose error is analyzed, and the structure and size of the robot are optimized. Firstly, the error of space climbing robot mainly comes from Delta mechanism. The forward and inverse kinematics solutions of delta mechanism are deduced, and the kinematics space of delta mechanism is solved. On this basis, the error model of hole axis skew at joint of delta robot is established by using geometric space vector method, and the pose error of delta mechanism is solved. The calculation results show that the skew pair of hole axis at joint of delta robot is skewed. The motion accuracy of the delta mechanism has a great influence; then, according to the functional requirements of the space climbing robot, the overall size planning of the robot is carried out, and then the Jacobian matrix condition number of the delta mechanism is solved to evaluate the motion transfer performance of the delta mechanism; the position and attitude errors and motion transfer performance of the delta mechanism are considered comprehensively, which are taken as the scale synthesis. Two objective functions are used to find the optimal size combination of the robot. Finally, based on the error sources of delta mechanism, the structure of delta mechanism is optimized.
Key words: Delta; Parallel Mechanism; Hybrid Mechanism; Kinematics Analysis; Path Planning; Jacobi