Novel design and kinematic analysis of a 5-DOFs robotic arm with three-fingered gripper for physical therapy

Abstract

This paper presents the design and kinematic analysis of a novel robotic arm for the automation of manual operations performed by physiotherapists. Conventionally, a repetitive task is performed to visualize inflamed tendons, joints and ligaments with many patients. Therapeutic ultrasound techniques are further used to heal them by efficient energy transfer. During both, visualization and healing process, physiotherapists move the hand-held transducer knob for a set of specified trajectories. To perform such actions, a dedicated robotic arm can reduce manual working hours of physiotherapists and relax them. In this work, a 5-degrees of freedom (DOFs) robotic arm with three-fingered gripper is designed and modeled in SolidWorks software. The design specifications of the robotic arm are decided in accordance with therapist’s arm and available ultrasonic therapy unit of institute hospital. The detailed forward, inverse, and velocity kinematic analysis of the robotic arm are presented using Denavit-Hartenberg (D-H) parameters and Jacobian matrix. From the simulation runs in MATLAB, the joint variables and joint angular velocities are estimated for a specified set of trajectory responses viz., spiral and lemniscate curves in the x-y plane. A set of specified trajectories is selected in consultation with the institute physiotherapist. Furthermore, the linear and angular velocities of the end-effector are estimated using velocity kinematics. The smooth and small magnitude of variation in joint angles, joint angular velocities and end-effector linear and angular velocities establishes a framework for reliable design.