Dual Constraint-Based Controllers for Wheeled Mobile Manipulators

A wheeled mobile manipulator, consisting of a mobile platform and a manipulator arm, can be used to provide assistive handling of loads without requiring large investments or changes in factory layout. This paper introduces a novel constraint-based control architecture in which such assistive tasks can be defined. From the same constraint-based task specification two constraint-based controllers are generated in such a way that the more accurate and higher bandwidth manipulator arm can compensate for the inaccuracies and lower bandwidth introduced by the mobile platform. The effectiveness of this approach is validated using a null-space motion task and a guided peg insertion task. The experiments clearly show an improvement in the accuracy of the null-space motion task and an increased comfort-level of the operator in the guided peg insertion task.