Design of an active orthosis for improved rehabilitation of stroke patients

Sammanfattning: To regain mobility in an affected limb after a stroke it is important to be consistent with rehabilitation exercises. The purpose of this project was to create an active orthosis for the elbow joint. The intended use of the orthosis is to help stroke patients during rehabilitation and to enable the possibility to use the orthosis at home without the assistance of a physiotherapist or other help. The active orthosis that was developed in the project is a further development of a passive orthosis developed at the Center for Bionics and Pain Research (CBPR) in Gothenburg. To make the orthosis active a servo motor was added to the elbow joint. To control the orthosis EMG-signals were collected from the participants bicep brachii and tricep brachii. The EMG-signals were thereafter interpreted by a machine learning algorithm in the open source program BioPatRec. The machine learning algorithm constructed a movement classifier based on data from a training set. The program thereafter sent a motor command with the intended direction to an Arduino. Lastly the Arduino sent a pulse width modulation (PWM) signal to the motor to move it a predetermined amount of degrees. Two different ways to obtain the data for the training set were designed. An evaluation test was performed to evaluate the methods. Seven participants made flexion and extension movements from endpoint to endpoint in the range of motion. The two training methods were considered to be equally good. It was possible to control the orthosis in both directions but it was easier to do the flexion movement than the extension movement. The participants did not feel that the orthosis movements were scary but they experienced a delay in the movement. With the end product it is possible to test the concept of an active orthosis but much development is still needed for it to be a rehabilitation tool for stroke patients.