Friction and backlash measurement and identification method for robotic arms

The paper presents a friction and a backlash identification method for robotic arms that are based on measurements performed during controlled robot motion. A modified friction model is proposed making use of which the linear least squares method can be applied for friction identification. The influence of the robot nonlinearities were also taken into consideration during the friction identification. The backlash gap was measured when the robot arm changes its direction taking into consideration the velocity and the drive motor current. A robot velocity control algorithm is also proposed for friction and backlash measurement. Experimental measurements are presented to show the applicability of the theoretical results.