Variable admittance control for hand exoskeletons in virtual reality-based rehabilitation tasks

Object manipulation is a crucial element of hand rehabilitation treatments. However, as a standalone process may result in being repetitive and unstimulating. In several studies robotic devices have been proved effective solutions in short and long term therapies for patients with motor dysfunctions and disabilities. Combined with virtual reality-based exercises, Robotics may greatly increase patients involvement, boosting not only the recovery outcome but also psychological aspects like satisfaction and confidence. Moreover, modern physics simulators can render forces from a virtual environment thus providing both visual and force feedback to the user. This work presents the development of a variable admittance control strategy for a rehabilitative hand exoskeleton designed to provide force feedback to the user while interacting with virtual objects in the Webots framework. By means of the proposed control, the device can both follow the user's intentions resulting almost transparent to the him/her, and providing a force feedback giving the feeling of handling real objects.