The objective of the study was to undertake a preliminary analysis of the operational accuracy of a prototype suspension therapy apparatus. This entailed the establishment of the kinematic relationship between the movements imposed by the actuators and the movements of the participants’ body segments. The experimental procedure involved the taking of measurements on six participants (average age 32 ± 8 years, weight 67 ± 7 kg, height 178 ± 7 cm). Five movement sequences were observed, including rotation of the head, shoulders, and pelvis, and alternating movement of the shoulders, relative to the pelvis, and the head, relative to the shoulders. The movement of body segments and actuators was recorded using a Vicon optoelectronic system, based on passive markers. A virtual kinematic model was prepared for each of the measurements. It was found that the relationship between the actuator-imposed rotations and the resulting segmental rotations depended on the movement sequence and the body segment involved. The mean head rotation was 46.4° ± 1.2° (27.8% greater than the actuator setting) and the mean shoulder rotation was 23.8° ± 2.4° (11.1% greater), whereas the mean pelvic rotation (20.1° ± 0.9°) showed near agreement with the actuator-imposed value. In alternating movement sequences, distinct directional patterns were observed: head rotation remained greater than the actuator setting, shoulder rotation showed near-agreement or moderate increases, and pelvic rotation in the shoulder–pelvis sequence was markedly lower than the actuator-imposed rotation. The device demonstrates a high level of efficacy in mapping movements, particularly with regard to pelvic rotation. Differences in head rotation indicate the need for further optimisation of movement sequences. The results suggest mapping stability for the majority of participants, with isolated deviations requiring further investigation.
Saternus et al. (Thu,) studied this question.