Error analysis of multi-legged walking robots based on forward kinematics

Determining precisely the motion of robot body is of great significance to the location and control of mobile robots. If the positions of each foothold and the driven joint variables are inaccurate, actual posture of the robot is likely to deviate from requirement. In this paper, based on the forward kinematics of a multi-legged walking robot, the posture accuracy of the robot is discussed in terms of errors of foothold positions and independent driven joint variables of the robot. The position errors of the dependent joints are firstly derived from the constraint equations which descript the kinematic relation between independent and dependent joints. The error of orientation matrix of the robot is then calculated. Finally, the position error of Center-of-Gravity of the robot is obtained on the base of the above calculation. The analysis process is verified through a numerical example.