StrokeSleeve: Spatially Distributed Tactile Feedback for Stroke Rehabilitation
Current Researchers: Karlin Bark, Frank Tan
Clinical Collaborators: Steven A. Jax, Laurel J. Buxbaum, Moss Rehabilitation Research Institute
Previous Researchers: Elizabeth Cha, Preeya Khanna, Pulkit Kapur, and Rikki Irwin
More than 780,000 Americans suffer a stroke each year  and it is the leading cause of long term disability in the United States. Approximately 80% of these individuals survive and undergo rehabilitation to regain motor functionality. Many of these patients are subsequently afflicted by ideomotor limb apraxia, a motor control condition that hinders one's ability to carry out skilled upper-limb movements, like those required for the activities of daily living . Although patients are still able to comprehend tasks and their sensory capabilities remain in tact, deficits in motor planning often prevent them executing the specified motions. Rehabilitation therapy is often used to improve their motor skills, but optimal treatment methods are undefined and still being developed.
Examples of performance by patients in the Ideomotor Apraxic group. (A) is the target pose demonstrated by a clinican. (B) displays the deficits exhibited by a patient with ideomotor apraxia even when vision is available to the patient. The patient's ability to mimic the pose when vision is not available deteriorates significantly (C). Image taken from Jax et.al, 2006 
Current therapy methods typically utilize virtual environments, providing patients with visual feedback as they perform repetitive arm movements to improve motor functionality, but patients often struggle to process such information. A therapist also provides hand-over-hand skilled guidance (“shaping”) to assist the affected arm in performing functional tasks. These training methods are work-intensive for the therapist and can become boring and laborious for the patient, thus presenting the need to develop alternative therapy methods. Newer rehabilitation therapy benefits from the use of virtual reality and assistive robotic arms. These newer technologies permit the delivery of enhanced feedback and guided practices as well as the option to record user performance for evaluation.
Tactile Motion Guidance System
Our goal is to develop a low cost sleeve that can measure the movement of the upper limb and assist the patient by providing tactile feedback at key locations. The feedback provided by the tactile system should guide the patient through a series of desired movements by allowing him or her to feel limb configuration errors at each instant in time.
Envisioned System for Kinesthetic Motion Guidance
To investigate the merits of our envisioned approach to stroke rehabilitation, we have created a prototype sleeve system. This wearable tactile interface has three main objectives. It should be comfortable and easy to wear without encumbering the user, it should continually and reliably measure the configuration of the user's arm in space, and it should provide intuitive tactile cues to guide the user into target configurations.
The Current StrokeSleeve Prototype
Our current prototype uses a Microsoft Kinect to measure a user's upper arm and forearm motions. The user is able to chose either their left or right arm for motion training. In addition, we are able to record and replay desired motions and trajectories.
A computer monitor displays a graphical representation of the user's arm motions and provides a wireframe overlay of a desired motion for an individual to learn. This helps the user see what the desired path is and make adjustments accordingly.
The haptic (vibrotactile) feedback is provided in the form of cuffs that are placed around the bicep and forearm of the user. Stretchable, compression arm sleeves are used to create a tight fit and accomodate a wide variety of individuals. Four, shaftless, eccentric mass motors are evenly distributed around the cuff and attached to the material using rubber coated plastic caps. This ensures that the actuators are close to the skin for good tactile sensation and localization of the vibration actuators.
We are currently testing the effects of providing haptic guidance cues in learning a new motion.
Alternative Forms of Tactile Feedback
We also aspired to explore forms of tactile feedback beyond the traditional vibrotactile approach. We designed four tactile actuators capable of tapping, dragging across, squeezing, and twisting the user's wrist. By creating sensations that are more natural and commonly experienced in everyday life than vibration, we hope that these actuators can give the user a more intuitive interface, particularly for guidance in wrist pronation and suppination. Each of these actuators is capable of replaying recorded human physical contact, as demonstrated in our actuators video.
 American Heart Association. Heart Disease and Stroke Statistics- 2008 Update, Dallas, Texas, 2008.
 S. A. Jax, L. J. Buxbaum, A. D. Moll, Deficits in movement planning and intrinsic coordinate control in ideomotor apraxia. Journal of Cognitive Neuroscience, Vol. 18, pp. 2063 - 2076, 2006.
K. Bark, P. Khanna, R. Irwin, P. Kapur, S. A. Jax, L. J. Buxbaum, K. J. Kuchenbecker. Lessons in Using Vibrotactile Feedback to Guide Fast Arm Motions. In Proceedings, IEEE World Haptics Conference, 261-266, June 2011. (pdf) (bib)
P. Kapur, M. Jensen, L. J. Buxbaum, S. A. Jax, and K. J. Kuchenbecker. Spatially Distributed Tactile Feedback for Kinesthetic Motion Guidance. In Proceedings, IEEE Haptics Symposium, pages 519-526, March 2010. (pdf) (bib)
P. Kapur, S. Premakumar, S. Jax, L. Buxbaum, A. Dawson, and K. J. Kuchenbecker.Vibrotactile feedback system for intuitive upper-limb rehabilitation. In Proceedings, World Haptics Conference, pp.621-622, 18-20 March 2009
This material is based upon work supported by the National Science Foundation under Grant No. 0915560. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.