Calibration procedure
shoulder abduction, pain
To calibrate the position of the robot, the shoulder height and upper arm length were manually measured using a measuring tape in the beginning of the first session and entered in the software. At the beginning of each session, the robot moved the flange to the respective clip-in position at 30° shoulder abduction. Once the brace was clipped to the arm, the arm was weighed by the robot to enable the calibration of robotic support. Afterwards, the patient’s specific range of motion (ROM) was evaluated, which consisted of two assessments: the active ROM, in which the patient could actively move the impaired arm, and the passive ROM without pain as guided and determined by the therapist. The passive ROM typically exceeded the active ROM in patients. This differentiation enabled the implementation of two different robotic support modes: (A) The support level was set to a constant level for both ranges, or (B) the support level within the active ROM was set to a constant level while the support of the movement beyond the active ROM increased dynamically until the patient achieved the desired movement. The robot enabled six support levels that were adjustable with increments of 20%, from 0 to 100%.