NONLINEAR PERFORMANCE INDEX (NPI) - A TOOL FOR MANIPULATOR DYNAMICS IMPROVEMENT

The precise control of manipulators depends nonlinearly on the velocit y of the motion as well as on manipulator configuration and commanded acceleration requiring complex control strategies. This paper presents a useful tool for identifying and quantifying nonlinear effects appea ring during the motion of any manipulator, the Nonlinear Performance I ndex (npi). The npi takes into account not only the geometrical parame ters defining the manipulator but also its structural dynamics through the use of inertial parameters like mass, inertia, centre of mass... The npi can be used in the design stage for analysing and reducing the se undesirable nonlinear effects in any general motion or in the traje ctory planning looking for paths along which more precise control is e xpected. The last part of the paper shows how this design optimisation and path planning has been applied to the Agribot, a fruit picking ro bot designed at the IAI.