Abstract: The effects of the joint clearance variables to the position repeatability of the robot end effector are analyzed using a two-dimensional vector method to define the joint clearance variables. According to the theory of probability, the probability density function of the robot end effector is developed based on the assumption of the distribution of the joint clearance randomness. And then error distribution function of the robot end effector is derived. The joint clearance error of RHJD4—1 6 DOF arc welding robot is analyzed by means of this method. The affects of the joint clearance to the uncertainty of the robotic position repeatability are outlined. And the restraining relation between the joint clearance and position repeatability of robot is given, which sets a theoretical foundation for the robot designing and precision analyzing.

Key words: Joint clearance, Repeatability, Robot, Composite grinding factor, Critical grinding depth, Machinable ceramics, Surface roughness, Undeformed chip thickness