Rehabilitating the hand is, in a sense, the neglected middle child of stroke recovery. Rehabilitation therapies (physical, occupational and speech) are proven methods, but also a precious resource. Occupational therapy (that would include but not be exclusively devoted to the hand) is typically only provided up to a maximum of 3 hours per week for six months or less, and little improvement is generally seen after that. In fact, fewer than half of stroke patients with upper limb impairment ever regain functional use! And, as one stroke patient concluded in personal discussions, "if the hand does not work, there is little incentive to use the arm at all..."

 

 

We implemented and tested proof of concept devices that assist with two movement patterns: full hand extension and fingertip pinch. These aim to address some of the hand impairment types most commonly encountered as stroke aftereffects. Each pattern assists with movement of multiple fingers (four and five, respectively) through the use of a single actuator. We quantitatively assessed the combined actuation force needed for assisting hand extension in stroke patients with spasticity and correlated the results with the spasticity level observed in stroke patients, measured using the Modified Ashworth Scale. [Publication: ICRA 2016]

For devices to be wearable in a functional context, they need intuitive, user-driven controls. We developed an electromyography (EMG) controlmethod for our exoskeleton hand orthosis for stroke patients. We applied EMG pattern classification to determine the user's intention either to open or to close the hand, and use this signal to produce physical movement assisted by the orthosis. [Video below: illustrations of orthosis operation under EMG control] [Publication: ICORR 2017]

 

We have also investigated multiple transmission mechanisms for a tendon-driven hand orthosis, with the goal of increasing tendon moment arms around the joints and thus increasing performance without the need for larger motors. [Publication: ICRA 2018][Video below: summary of our paper]

 

Building on the EMG expertise developed in this project, we also introduced new methods for teleoperating stand-along robotic hands using forearm EMG. We use a teleoperation subspace to map between the human pose space and the pose space of dexterous but non-anthropomorphic robot hands. We showed that such methods can be used for teleoperation using either an instrumented glove and an EMG armband. [Publications: ICRA 2018, ICRA 2019, journal version under review][Video below shows a summary of our method used with an instrumented glove]

We then performed a more extensive clinical study of our hand orthosis, working with 11 stroke survivors over an extended training period consisting of more than 15 sessions. Our results showed that the MyHand orthosis has potential for use either as a rehabilitation device or as an assitive device. [Publication: under review][Video below illustrates our study and the use of the orthosis]