This paper proposes an algorithm for identification of contact conditions between a grasped object and external environment from position and velocity information of a robot hand. The contact conditions mean contact type, contact position, and contact force. Soft finger contact type, line contact type, and plane contact type are considered in addition to point contact type. The contact type is identified by rank of the matrix that places estimated angular velocity of the object at contact point. Contact position, contact normal and contact line are also estimated. This method has the following merits as compared with the method using 6-axes force information described in the previous paper. The identification problem is reduced to the problem of solving linear equations. The required number of active sensing motion is less.

This paper discusses a method for identification of contact conditions from the information of 6-axes force sensor equipped with a robot hand. The previous paper (1999) has the following problems: the noise of sensing force was not considered, and hence the estimates obtained by the previous method are biased from true value, and the identification of contact types depends on an unknown contact position. In this paper we consider the noise of force. We propose a method of removing the bias from the estimates. Hence, it is guaranteed that asymptotically unbiased estimates are obtained. The contact types can be judged by eigenvalues of a covariance matrix, which is derived from estimates of the contact moment. The effectiveness of the algorithm is demonstrated by simulations.