A novel calibration method for multi-robots system utilizing calibration model without nominal kinematic parameters

In this manuscript, a novel method for multi-robots system calibration utilizing a calibration model based on the Product of Exponentials formula (POE formula) without nominal kinematic parameters is proposed. The calibration model is characterized by the adjoint transformation which is adopted to represent the transformation relationship between two twists. Compared with the traditional POE formula model for calibration, the proposed model merely depends on the reference configuration rather than base frame and reference configuration. Then a coordinate which describes the robot is fixed and the end-effector pose with respect to the predetermined coordinate is measured several times. Least square method is adopted to identify the exact POE formula model with respect to the predetermined coordinate. The results of simulation and experiment reveal that 1) with the proposed model, nominal kinematic parameters are not required to establish the initial kinematic equation, 2) the result of the calibration is not only identifying the exact kinematic parameters of the robot but also determining the pose of the robot base frame with respect to a predetermined coordinate, 3) the calibration method can increase the accuracy of multi-robots system.