Characterization of PKM dynamics in terms of system identification

Abstract

This paper presents a study on the dynamics of parallel kinematic mechanisms (PKMs), and the determination of which dynamics terms are candidates for identification. Using D'Alembert's method, the dynamics equations of motion are derived with inclusion of the strut masses. These equations are used to solve for the required actuator forces that are grouped according to inertial and gravitational components. Comparative observations are made using Euclidean norms and sample trajectory-based characterizations. Detailed results are presented for the University of Florida Special 6-6 PKM and two geometric variants. Observations of the Hexel PKM machine tool and Ford PKM vehicle simulator's dynamics are also presented to further demonstrate shifts in the dynamics effects. Experimental validation substantiates the simulation-based results and highlights the measurement difficulties as well as delineating a need for an iterative methodology for full dynamic system identification implementation.

Keywords

hexapod dynamics parallel kinematic mechanisms system identification

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