Hysteretic behaviour of tape-spring actuators:: Influence on the deployment of an hexapod

This paper focuses on a deployable telescope based on an hexapod equipped with tape-spring coiling devices. It aims at understanding the effects of parameters uncertainties on the deployment. Stability during the deployment can be better investigated if localized nonlinearities are identified. The deployment analysis starts with the establishment of a single degree of freedom (DOF) force-deflection model for a single deployable coiling device, the parameters being identified experimentally. In a second step, this actuator model is implemented in a simplified bipod model similar to a planar three-DOF mechanism giving a first approach of the deployment behaviour. Therefore, the two coiling devices are modeled as parallel phenomenological models. In the last part, six actuators models are used to perform a complete model of the deployable hexapod. Finally, the hexapod response is predicted by modifying the restoring force of one of the six actuators.