Initial patient testing of iPAM - a robotic system for Stroke rehabilitation

iPAM is a dual robotic system currently being developed in the UK under a NHS New and Emerging Applications of Technologies (NEAT) grant. The aim of the system is to provide assistive upper-limb therapeutic excercise for post-stroke rehabilitation. iPAM features two co-ordinated, pneumatically-actuated robotic arms which attach to the patient´s forearm and upper-arm to provide assistance, mimicking the intervention of a physiotherapist. The system design and manufacture has been completed and the robot installed at a local hospital (St Mary´s, Leeds PCT, UK) inside a community rehabilitation unit. The controller is currently developed and ´tuned´ to provide gravity compensation for robots, removing any potentially damaging loads on the patient arm. The control scheme has been tested in simulation and using a mechanical arm model to ensure safe operation. Two small scale trials have been conducted to assess two facets of the robot design; firstly the mechanical design of the system to unimpede normal arm movement and secondly, its ability to provide varying levels of lift to the patient´s arm to increase range of movement. The former of these trials compares free arm movement in healthy volunteers and Stroke patients with that when attached to iPAM. The robot was configured to compensate for its own weight, so the human upper-limb was unloaded. It was found that the robot had no significant affect on movement patterns. The second group of patient trials evaluated the operation of various levels of assistance against gravity. Patients were asked to point to a target with varying degrees of ´lift´ applied to their upper and lower arm. In those patients with significant upper-limb impairment it was found that higher values of ´lift´ improved the extent of reach but altered the movement pattern. Results from the trials demonstrated the suitability of certain modes of operation depending on the severity of patient disability.