Destabilizing effects of muscular co-contraction in human-machine interaction

We are studying the control of human arm movements that are constrained by physical interaction with a machine such as a hand controller or a telerobotic system. One of the difficulties in controlling this type of constrained interaction is instability in the human arm-machine system. In this article, we present simulation results showing that increasing muscular co-contraction destabilizes human-machine interaction. Results of this work may have an impact on the design of machines that are to interact with humans.