Spring-Follower-Cam Assembly for Muscular Training at Different Speeds

Abstract

Conventional equipment for muscular rehabilitation and training uses passive load systems. This work seeks the creation of an alternative resistance generation device for the skeletal muscle contraction to be applied in conventional machines of muscular training and physiotherapy. The proposed device uses a group spring-follower-cam to produce the resistance and does not use cables, belts or chains. The device was designed to generate mechanical resistance through low inertia set, accessibility, modular and low-cost to be adapted on training machines. This device consists of a cam-follower pair connected to a compression spring. Its operating principle is based on the pressure angle variation between the cam-follower pair. The mathematical modeling and the numeric solution for the cam profile is presented. It was noted that prototype can be applied in high speeds unlike conventional equipment. The maximum torque curve available and the torque curve obtained in the device approached, as the movement training approached motor gesture, with maximum errors of about 10 %. The results confirm that the device is capable of generating a resistance profile that resembles the maximum available torque profile at the joint user when performing certain movement training, which can more adequately represent the motor gesture to be trained. Two case studies were conducted using the motor gesture of judo training and rower’s movement which mainly uses elbow flexion.