The "Beam-Me-In Strategy" - remote haptic therapist-patient interaction with two exoskeletons for stroke therapy

We present a robot-assisted telerehabilitation system that allows for haptic interaction between therapist and patient over distance. It consists of two arm therapy robots. Attached to one robot the therapists can feel on their own arm the limitations of the patient's arm which is attached to the other robot. Due to the exoskeleton structure of the robot, movements can be performed in the three-dimensional space.

Fifteen physical and occupational therapists tested this strategy, named "Beam-Me-In", while using an exoskeleton robot connected to a second exoskeleton robot in the same room used by the study experimenter. Furthermore, the therapists assessed the level of impairment of recorded and simulated arm movements. They quantified four typical impairments of stroke patients: reduced range of motion (active and passive), resistance to passive movement, a lack of ability to fractionate a movement, and disturbed quality of movement.

On a Likert Scale (0 to 5 points) therapists rated the "Beam-Me-In" strategy as a very useful medium (mode: 4 points) to evaluate a patient's progress over time. The passive range of motion of the elbow joint was assessed with a mean absolute error of 4.9^∘ (absolute precision error: 6.4^∘). The active range of motion of the elbow was assessed with a mean absolute error of 4.9^∘ (absolute precision error: 6.5^∘). The resistance to passive movement (i.e. modified Tardieu Scale) and the lack of ability to fractionate a movement (i.e. quantification of pathological muscle synergies) was assessed with an inter-rater reliability of 0.930 and 0.948, respectively.

The "Beam-Me-In" strategy is a promising approach to complement robot-assisted movement training. It can serve as a platform to assess and identify abnormal movement patterns in patients. This is the first application of remote three-dimensional haptic assessmen t applied to telerehabilitation. Furthermore, the "Beam-Me-In" strategy has a potential to overcome barriers for therapists regarding robot-assisted telerehabilitation.