Design of a Rotational Hydroelastic Actuator for a Powered Exoskeleton for Upper Limb Rehabilitation. - Arno H. A. Stienen; Edsko E. G. Hekman; Huub ter Braak; Arthur M. M. Aalsma; Frans C. T. van der Helm; Herman van der Kooij (IEEE Trans. Biomed. Eng., 2010)