Dynamic Decomposition and Adaptive Control of a Six-Degrees-of-Freedom Robotic Manipulator

Abstract The complete dynamic model of a 6-degrees-of-freedom (DOF) robotic manipulator is very complicated, having a large number of nonlinear terms, and so it is very difficult to be used for actual on-line control. The purpose of this paper is to provide a method for decomposing the dynamical model of such a 6-IDOF manipulator in two 3-DOF submodels (one for the arm and one for the wrist) which can be successfully used both for simulation and control purposes. The arm submodel takes into account the effect of the wrist and of the manipulator task requirements, in the form of an external force/ torque pair expressed in tool coordinates. The influence of the robot task is similarly included in the wrist dynamic model. Then the paper shows how the model reference adaptive control (MRAC) technique can be used on this two-part robot model. As a simulator of the 6-DOF robot, the exact dynamic model, based on the Newton Euler method, is employed. Computational experimental results are included which show the effectiveness of the approach.