Base parameters of manipulator dynamic models

A base parameter set as a minimum set of inertial parameters whose values can determine a dynamic model uniquely is investigated for a general parallel and perpendicular manipulator with rotational joints only. The notion of a base parameter is useful for an efficient and accurate identification of the manipulator dynamic model. A set of inertial parameters described in linear combinations of link parameters directly and completely in closed form is given and proved to constitute a base parameter set. It can be derived from this that the minimum number of inertial parameters whose values can determine the dynamic model is 7N-4β₁ (7N-4β₂-2 if the first joint axis parallel to the gravity vector), where N is the number of links in the manipulator, and β₁ is the number of links connected by joints whose axes are always parallel to the first joint axis. After defining the base parameter, it is also shown that any base parameter set can be obtained from one base parameter set by a nonsingular linear transformation. The method adopted has the potential advantage of determining the relations between base parameters and manipulator motions