An iterative method for solving the inverse kinematic problem of three-joints robotic fingers with distal coupling.

This paper introduces a methodology for finding a solution to the inverse kinematic problem of underactuated manipulators composed of a three-link revolute joints planar mechanism with mechanical coupling. The proposed method consists in solving iteratively a set of algebraic equations defining the Inverse Kinematic Model (IKM) of a 3R mechanism whose rotational joints are first considered independent. The respect of the mathematical constraint due to the mechanical coupling between certains axes is taken into account in the procedure by introducing an internal variable whose value is updated iteratively. The value of this internal variable is increased at each iteration until the coupling relationship is satisfied. The proposed methodology is applied to solve the IKM of a multi-phalanx robotic finger whose kinematics follows a human-like finger coupling between the intermediate and distal phalanges.