Application of non-linear H-infinity control to the Tetrabot robot manipulator

In this paper, an application of a non-linear H-infinity control law for an industrial robot manipulator is presented. Control of the manipulator moti on is formulated into a non-linear H-infinity optimization problem, namely optimal tracking performance in the presence of modelling uncertainties and external disturbances. Analytical solutions for this problem are implement ed on a real robot. The robot under consideration is the six-degrees-of-fre edom GEC Tetrabot. Investigations are made into the selection of weights fo r the H-infinity controller and it is shown how different selections of wei ghts affect the Tetrabot performance. The authors believe this to be the fi rst robotic application of nonlinear H-infinity control. Comparisons of the proposed control strategy with conventional proportional-derivative and pr oportional-integral-derivative controllers show favourable performance of t he Tetrabot under the new non-linear H-infinity control scheme.