ITERATIVE INVERSE KINEMATICS WITH MANIPULATOR CONFIGURATION CONTROL

A new method, termed the offset modification method (OM method), for s olving the manipulator inverse kinematics problem is presented. The OM method works by modifying the link offset values of a manipulator unt il it is possible to derive closed-form inverse kinematics equations f or the resulting manipulator (termed the model manipulator). This proc edure allows one to derive a set of three nonlinear equations in three unknowns that, when numerically solved, give an inverse kinematics so lution for the original manipulator. The OM method can be applied to m anipulators with any number of degrees of freedom, as long as the mani pulator satisfies a given set of conditions (Theorem 1). The OM method is tested on a 6-degree-of-freedom manipulator that has no known clos ed-form inverse kinematics equations. It is shown that the OM method i s applicable to real-time manipulator control, can be used to guarante e convergence to a desired endpoint position and orientation (if it ex ists), and allows one to directly choose which inverse kinematics solu tion the algorithm will converge to (as specified in the model manipul ator closed-form inverse kinematics equations). Applications of the me thod to other 6-DOF manipulator geometries and to redundant manipulato rs (i.e. greater than 6 DOF geometries) are discussed.