Transparent force control for Body Extender

The Body Extender is a whole-body exoskeleton designed to operate in unknown and difficult environments, for instance in disaster areas. The Body Extender allows the wearing operator to increase its force while maintaining a high level of perception. The present work describes a novel control system for the Body Extender. We designed the control loop in such a way the interaction forces are perceived as a fraction of the overall external forces. These percentages can be decided at design time as a trade-off between sensitivity and force extension. To realize control, the algorithm includes an on-line estimation of the transported mass. The algorithm has been implemented for one arm of the Body Extender. The identification, the performances and the stability limits has been tested on a simpler structure with only one joint. In the following we will show the basis of the developed algorithm as well as the results achieved on the test platform.