Throwing motion design based on minimum sensitivity with respect to error covariance of robot dynamic parameters

Abstract

Throwing by a powered manipulator is an effective way for wide range transportation of an object and carrying an object in unmanned environments. The main problems of throwing are (i) how far the manipulator can throw the object and (ii) the accuracy of the landing position. Focusing on (ii), this paper proposes sensitivity analysis of the landing position with respect to the error covariance of dynamic parameters. Focusing on a planar 3-DOF manipulator, (1) the minimum set of dynamic parameters is introduced and identified based on a frequency weighted method for a nonlinear system, and its error covariance is also identified. (2) The calculation algorithm for sensitivity of landing position with respect to the minimum set of dynamic parameters is proposed. (3) By considering the error covariance of identification, an optimal throwing is designed and evaluated by simulations and/or experiments. Moreover, (4) the principal of sensitivity analysis is discussed from error ellipsoid point of view, and zero error throwing is designed.