Automated complex of motion control based on vibrotactile feedback for rehabilitation

Abstract

This report presents a technique for using vibrotactile feedback for rehabilitation of patients after an operation on the hand with a suture on the tendon. The task is to limit the arm muscle tension using vibrotactile feedback, which aims to prevent exceeding the preset force threshold and thus protect the stitched tendons from rupture in the post-operation period. The study goals were to develop an automated complex able to record muscle activity (myography) and induce vibrotactile signals; and develop an algorithm able to inform the patient (via tactile sensation) that the muscle tension is exceeded. These developments were aimed at preventing possible tendon rupture and maintaining smooth recovery after surgery. Materials and Methods. A wireless system consisting of a single-channel myograph combined with a tactile pulse generator (vibration actuator) was used. The system was placed on the forearm and was controlled from a remote computer in both manual and automatic modes using a software package developed in the MATLAB environment. The real-time analysis of the myographic signal allowed us to determine the force of muscle contraction. When the preset threshold (20% of the maximum) is exceeded, the system triggers a short burst (200 ms duration) of vibration pulses. This vibration stimulus informs the subject about the exceeding or redundant muscle tension, after which he/she stops further exercise. Results. Here we show that the vibrotactile feedback signal lasting hundreds of milliseconds is well perceived by the subject and allows him/her to respond so not to exceed the preset muscle force threshold. This biological feedback is viewed as physiologically favorable for patients because it can automatically inform them about excessive muscle contractions that are undesirable in the rehabilitation period. In the long term, this feedback mechanism may help forming normal patterns in patients.