Abstract:

This paper describes the kinematic error model of Navi-Robot, a novel hybrid parallel/serial robotic system, designed to be used for several medical applications. This calibration technique allows modeling the stiffness of the structure taking into account the influence of non-perfect geometry of serial and parallel chains caused by manufacturing errors and mechanical tolerances. The experimentally identified errors have been used to predict, and compensate for, end-point errors as a function of configuration and loads applied, improving the system absolute accuracy. Experimental results show that the adopted methodology is able to effectively correct for the system errors with a significant improvement of robot accuracy. After calibration, the mean/maximum position errors on the end-effector are reduced from 0.743 mm/1.236 mm respectively, to 0.503 mm/0.902 mm.

Keywords: error model; kinematic calibration; hybrid robot.