Base frame calibration for coordinated industrial robots

To solve the problem of base frame calibration for coordinated multi-robot system, a new method is proposed in this paper. It is carried out through a series of “handclasp” manipulations between two coordinated robots, then a preliminary result can be reached by the calibrating equation. After that, in order to make sure that the calibrated rotation matrix is orthonormal, an optimal estimation of the relative rotation between the base frames of coordinated manipulators is solved out under the criterion of optimal Frobenius norm approximation. By the quaternion representation for rotation matrix and the Lagrange Multiplier method, an orthonormal matrix can be reached which is just the unknown calibrating result for base frames of the coordinated robots. Simulation and experiment results have verified the validity and effectiveness of the proposed method.

► Calibration method of base frames between coordinated manipulators is proposed.
► Orthonormalization for rotation matrix is reached under Frobenius norm approximation.
► Optimal approximation is obtained by quaternion and Lagrange Multiplier method.
► Calibration is carried out by a series of handclasp manipulations without other sensors.