An error-similarity-based robot positional accuracy improvement method for a robotic drilling and riveting system

It is important to improve the absolute positional accuracy of the industrial robots used in the robotic drilling and riveting systems. The purpose of this paper is to propose a method to compensate for the absolute positional errors of the industrial robots. Firstly, the spatial similarity of the positional errors is qualitatively and quantitatively analyzed using semivariogram function and experiments. Secondly, the positional error model is established based on the spatial similarity, and a linear unbiased optimal estimation method of the target positional errors is proposed. Finally, experiments are used to verify the proposed methods with measuring the robot's positional errors after compensation. The analysis shows that there is a spatial similarity of positional errors in the robot joint space, which can be used to establish error model and to estimate the target's positional errors. Experimental results show that the proposed method can reduce the maximum absolute positional errors by 84.08 % from 2.01 to 0.32 mm, which can meet the accuracy requirements of the robotic drilling and riveting system.