A 'basis trajectory' approach to the inverse dynamics formulation of robot manipulators

Abstract

A method, called the trajectory pattern method for formulating the inverse dynamics of rigid-body and nonredundant manipulators is presented. The method is based on dividing the trajectories into different groups (patterns), where each pattern produced an inverse dynamics model with a fixed structure. The time history of motion along a given path is described by an appropriate sinusoidal time function and its harmonics. This description leads to trajectory-specific inverse dynamics equations that are expressed in terms of the sinusoidal time function and its harmonics. The inverse dynamics models are grouped into different classes according to the number of harmonics present in their equations. The models are ideal for use in model-based tracking controllers with full compensation of the nonlinearities. They eliminate real-time computations in the control loop and provide the basis for reducing the effects of model parameter inaccuracies. The use of the method to determine the inherent characteristics of the manipulator dynamics and the development of systematic model approximation techniques is demonstrated