Desenvolvimento de sistema para controle de velocidade de esteiras ergométricas

Abstract

The use of robotic structures for human gait rehabilitation can facilitate the work of healthcare professionals involved in the process and assist in the individual’s recovery. In this context, the structure named HOPE-G is being developed at the Automation and Robotics Laboratory (ARL) of the Federal University of Uberlândia’s Mechanical Engineering Faculty. The goal is to develop a system that allows the individual to perform as much of the rehabilitation protocol as possible without restricting the natural movement of the individual. Among the elements that compose HOPE-G, is a split treadmill, i.e., two treadmills positioned side by side that will be used in gait retraining. The idea is to make the treadmills move at slightly different speeds, forcing the individual to adopt distinct step rhythms on each leg. This can help in the recovery of leg coordination. For HOPE-G to function properly, it is necessary to develop a control system and an electronic circuit that make the treadmills follow speed references provided by a healthcare professional or an external system. These are the objectives of the present work. More specifically, the aim is to develop and implement speed controllers for HOPE-G’s treadmills. The work is carried out by modifying commercially available ergometric treadmills already present in ARL, to reduce the development time. Initially, these treadmills were modified to enable speed measurement and speed adjustment through an Arduino UNO without significant delays. Then, through experimental tests, mathematical models were obtained to describe the relationship between the average motor voltage applied and the linear speed developed by the treadmills. From these models, two controllers (one for each treadmill) are designed using the root locus method. The performances of these controllers are verified through simulations and experimental tests. Both show that the controllers can guide the treadmills speeds to reference values according to project requirements. With a patient on the treadmills, the performances of the controllers were affected due to the inconsistency of human gait. However, it was considered that the results were satisfactory with measured speeds remaining around 20 % of the established references, thus fulfilling the project proposal.