Intelligent Therapeutic Robot: Design, Development, and Control

Abstract

This research contributes to developing an Intelligent Therapeutic Robot (iTbot) designed to provide therapy to patients with upper limb impairment due to stroke, injury, and other trauma. This robot aims to implement robotic rehabilitation based on principles of motor rehabilitation and Neuroplasticity. The iTbot, as developed in this research, can provide end-effector type rehabilitation exercises in various configurations, including motion in the vertical and horizontal plane. It can provide passive, active, and active-assisted rehabilitation therapies to patients with limited upper limb mobility. The iTbot has been designed with simplicity in mind with a minimum viability approach. With a minimum amount of custom fabricated parts, the design, build, control, and operation of this robot have reduced complications while providing a wide range of therapeutic exercises. iTbot’s manually adjustable orientation allows it to offer rehabilitation exercises in either vertical or horizontal workspace with only two degrees of freedom. To facilitate such a therapeutic robot’s operation, which can operate in multiple physical orientations, model-based control strategies including modified Computed Torque Control (mCTC) and newly developed Sliding Mode with intelligent Reaching Law (SMiRL) have been implemented as iTbot’s control method. Various experiments mimicking real-world application scenarios have been performed to compare the two controllers’ operating performance with the traditional Proportional, Integral, Derivative (PID) control method. To provide active and active-assistive rehabilitation exercises, iTbot employs a six-axis force-torque sensor as its input along with an adjustable admittance-based control strategy. This allows iTbot to either provide assistive or resistive rehabilitation exercises with the same system, enabling applying multiple principles of robot-aided rehabilitation in a single robot. Furthermore, iTbot can be used as a physical interface to video game and virtual reality-based rehabilitation exercises, enabling implicit and explicit feedback principles of motor rehabilitation.