Stroke is the leading cause of long-term disability in developed countries. Due to population aging, the number of people requiring rehabilitation after stroke is going to rise in the coming decade...

An elbow assisting device is presented as based on a cable-driven parallel mechanism with design solutions that are improvements from a previous original design. The new mechanism, ideal for domestic use, both for therapies and exercises, is characterized by low-cost, portable, easy-to-use features that are evaluated through numerical simulations and experimental tests whose results are reported with discussions.

Rehabilitation robots help the treatment of diseases by performing cyclic exercises for a long period of time. These exercises must perform movements of the patient’s limbs; thus, the robots are required to be flexible and safe. Among rehabilitation robots, cable robots are widely used due to their unique properties, such as being lightweight and the possibility of being equipped with magnetic hooks to improve both safety and ease of use. However, the elasticity and flexibility of cables result in vibrations of the payload and hooks. In this paper, the forced vibrations due to rehabilitation exercises are studied. Since the previous studies of the authors showed a weak coupling between longitudinal and transverse vibrations, a two-cable planar model for the study of transverse vibrations is developed. The model makes it possible to study the forced transverse vibrations due to both cable motion and robot motion. Stiffness and damping of the patient’s arm are considered. Results show that the cable system exhibits a simple linear behavior when excited by robot motion and a non-linear behavior when excited by cable motion.

Practicing walking motions while supine might help accelerate recovery after neurologic injury. This paper presents the design, modeling, and initial testing of a novel cable-driven device called AirStep that compensates for the weight of the legs, facilitating air-stepping practice while supine. AirStep integrates multiple mass-spring counterbalancing mechanisms to minimize the effect of gravity throughout the entire gait cycle such that patients can perform active or passive stepping motions in a near-zero gravity environment. Handles allow a rehabilitation therapist to manually assist leg motion through the cables as needed. Data acquired from an optical motion capture system validated the mathematical model of the AirStep, showing that the leg trajectories in air-stepping resembled those from running. In pilot testing, two individuals with spinal cord injury (SCI) required manual assistance at the hips from a physical therapist to achieve step-like motions through the AirStep interface. AirStep can apply low-forces, allow stepping in the supine position, and can quantify changes in patient-generated force production. Compared to other rehabilitation robots, AirStep offers the advantages of a low-cost mechanical structure, high acceptability by the patient and easy transportability aside a hospital bed, making the AirStep a good candidate for adoption in the early-stage gait rehabilitation.

Cable robots are widely used in the field of rehabilitation. These robots differ from other cable robots because the cables are rather short and are usually equipped with magnetic hooks to improve the ease of use. The vibrations of rehabilitation robots are dominated by the effects of the hooks and payloads, whereas the cables behave as massless springs. In this paper, a 2D model of the cables of a robot that simulates both longitudinal and transverse vibrations is developed and experimentally validated. Then the model is extended to simulate the vibrations of an actual 3D robot in the symmetry planes. Finally, the calculated modal properties (natural frequencies and modes of vibration) are compared with the typical spectrum of excitation due to the cable’s motion. Only the first transverse mode can be excited during the rehabilitation exercise.