Uncertainty of estimated parameters of contact conditions by active force sensing

When a grasped object is in contact with an external environment, it is required to identify contact conditions prior to performing assembly tasks. The contact conditions include contact position, contact force, contact type, direction of contact normal, and direction of contact line between the object and the environment. The contact type is assumed to be a point, soft-finger, line, or planar contact type with friction. These contact parameters are identified by active force sensing. Moreover, uncertainty of the estimated parameters is derived. This paper formulates least-squares functions including contact position, direction of contact normal, and direction of contact line. The uncertainty is derived by using an amount of each function. The effectiveness of this method is verified by using numerical examples. As a result, we obtain the novel knowledge that contact types can be distinguished by the uncertainty.