gms | German Medical Science

Objectives: Previous studies have highlighted the possibilities that robotically assisted therapy approaches for CRPS patients – especially for those with afflictions of the hand – could provide to their recovery process. CRPS is most often preceded by injury and/or surgery of the afflicted limb, resulting in a loss of motivation for the patient to move their afflicted hand. At this time, CRPS therapy remains a costly and time-intensive process with little empirical data available and measured to judge the success of the individual therapy approach. For this reason, a previous prototype was used to further develop new robotic devices that extend to the entirety of the hand.

Methods: A previously developed prototype that actuated only the index finger of the right hand was taken as a baseline for development. Three different actuation methods and structures were developed and applied to an entire hand. All three approaches also possess the ability to measure the angle between different finger elements and allow for the precise measurement of the force applied by a servo onto the finger or measure the force available to the patient. Attention was given to use as many of-the-shelf components and to keep the number of individual components as low as possible, in order to keep the barrier to entry for the building and usage of these devices as low as possible. For this, the choice was made to switch to cheaper servo and spring pairings or servo-servo one instead of expensive linear actuators. The first concepts loosely follows the actuation concept of the system developed for the right index finger. The second concept was chosen, to investigate a pairing of active actuators – one for extension and one for flexion of each finger – as a possible solution for exoskeletons for the hand. The third concept was chosen to explore alternative, simplified kinematic linkage structures compared to the first concept.

Figure 1 [Fig. 1], Table 1 [Tab. 1]

Results and conclusion: All three different prototypes were able to be worn without any restriction to hand movement. They can also be integrated in previously developed gamification approaches.