Design and Development of a Twisted String Exoskeleton Robot for the Upper Limb

Abstract

Design and Development of a Twisted String Exoskeleton Robot for the Upper Limb Lei Jiang High-intensity and task-specific upper-limb treatment of active, highly repetitive movements are the effective approaches for patients with motor disorders. However, with the severe shortage of medical service in the United States and the fact that post-stroke survivors can continue to incur significant financial costs, patients often choose not to return to the hospital or clinic for complete recovery. Therefore, robot-assisted therapy can be considered as an alternative rehabilitation approach because the similar or better results as the patients who receive intensive conventional therapy offered by professional physicians. The primary objective of this study was to design and fabricate an effective mobile assistive robotic system that can provide stroke patients shoulder and elbow assistance. To reduce the size of actuators and to minimize the weight that needs to be carried by users, two sets of dual twisted-string actuators, each with 7 strands (1 neutral and 6 effective) were used to extend/contract the adopted strings to drive the rotational movements of shoulder and elbow joints through a Bowden cable mechanism. Furthermore, movements of non-disabled people were captured as templates of training trajectories to provide effective rehabilitation. The specific aims of this study included the development of a two-degree-of-freedom prototype for the elbow and shoulder joints, an adaptive robust control algorithm with cross-coupling dynamics that can compensate for both nonlinear factors of the system and asynchronization between individual actuators as well as an approach for extracting the reference trajectories for the assistive robotic from non-disabled people based on Microsoft Kinect sensor and Dynamic time warping algorithm. Finally, the data acquisition and control system of the robot was implemented by Intel Galileo and XILINX FPGA embedded system.

Exoskeleton Recognition of Human Movement Intent Based on Surface Electromyographic Signals: Review

“…The evolution of middle-level mechanical architectures in exoskeletal design has transitioned from an initial emphasis on rigid materials to an increasingly prevalent integration of flexible or hybrid materials, encapsulating advancements in driving methods, structural flexibility, and material transformation. Regarding driving methods, beyond conventional hydraulic, pneumatic, and motor-driven mechanical systems, contemporary developments have introduced cost-effective and lightweight alternatives, such as the twisted rope drive [18] and twisted tube drive [19] integrated into lower limb exoskeleton devices. Studies have suggested that the international exploration of these methodologies commenced around 2017, with domestic Chinese initiatives gaining by 2020.…”