Method
Movement workspace measurement with the ARMEO Spring
To measure a subject’s movement workspace in the ARMEO Spring, the subject has to be seated on a chair. The device is then aligned to the patient. The alignment reference of the device to the subject is the vertical axis through the subject’s shoulder joint (humero-scapular joint). The subject’s arm is fitted to the exoskeleton and the height of the device as well as the upper and lower arm length and upper and lower arm weight support are defined individually for each subject, according to the user instructions. The movement workspace was calculated by using the x (right-left movement), y (up-down movement) and z (far-close movement) axes of the Cartesian coordinate system with its origin set as the shoulder joint of the device. Subjects are asked to move their arm to the maximal right position, whilst maintaining a straight and stable trunk position, and to hold this position for 3–5 seconds, then move the arm to the maximal left position
keeping a stable position and again holding the position for 3–5 seconds, and so forth for maximal top, bottom, forward and close (hand in front of the chest) position (see Figure 1). Subjects were not provided with knowledge about their results. During the movement the positions of the endpoint (hand) were recorded using the standard ARMEO Spring software [9].