Development of a participation assessment system based on multimodal evaluation of user responses for upper limb rehabilitation

The patient's active participation in exercises is a crucial factor to increase the functional outputs received from therapy. For improving the patient's active and voluntary involvement, the difficulty levels of therapy tasks and the device assistance are adjusted based on the patient's therapy performance. However, the existing performance evaluation methods are based on either some specific device designs or certain therapy tasks. In this work, a patient performance evaluation method is proposed based on a multimodal sensor fusion formed by the trajectory tracking error signal and the patient's physiological responses (heart rate and skin conductance) during the upper extremity rehabilitation. The novelty of the system is assessing the patient's performance independently from any device designs or therapy tasks. The developed system also evaluates the patient's tiredness and slacking, which are substantial factors affecting the therapy performance. The patient's upper limb joints' angles are measured via inertial measurement unit sensors. Arm movements of the patient are estimated by an upper limb kinematic module for evaluating the trajectory tracking. The patient's performance, tiredness, and slacking are assessed by a fuzzy inference system using physiological responses and exercise profile. The developed system is tested experimentally with healthy subjects on five therapy tasks. Also, for demonstrating the proposed method efficacy, additional experiments have been performed for different cases while measuring the sEMG signals of the subjects. The experimental results showed that the proposed system estimates subjects’ participation successfully and adjusts the therapy tasks according to subjects' performance and tiredness.