Design and Kinematics Analysis of Parallel Robots for Ankle Rehabilitation

Abstract

Ankle joint injury is a common athletics injury in clinic. It can be treated in a medical way, besides, rehabilitation exercises are needed, sufferers can regain the ankle joint's function to the greatest extent and enhance the proprioception. In this paper, a medical treatment robot is proposed for ankle joint rehabilitation exercises, in which the 3-RSS/S parallel mechanism is adopted based on the ankle joint's movements. The mechanical design is described and the inverse kinematic is derived, as a result, the Jacobian matrix is obtained. Furthermore, a reality model of the robot is built by UG and simulated under the ADMS environment. It shows the design can meet the needs of ankle joint rehabilitation movements. In order to validate these concepts, the first prototype is developed that driven by three torque motors and equipped with force sensor for sensing the interaction force between patient's foot and robot. At last, the robot's control system is presented in the paper.

Assist On-Ankle: a reconfigurable ankle exoskeleton with series-elastic actuation

“…Unlike the Stewart platform-based design, the degrees of freedom (DoF) of this device match those of the human ankle and a center strut is employed in the kinematics to achieve high structural stiffness. Spherical 3RSS/S 1 (Liu et al 2006) and Agile Eye (spherical 3RRR) (Malosio et al 2014) mechanisms have also been used for ankle rehabilitation. These devices possess good load carrying capacities with compact designs.…”

“…These devices possess good load carrying capacities with compact designs. 3RSS/S mechanism in Liu et al (2006) relies on force sensors for the control, while a smooth motion control, based on a minimum jerk reference trajectory, validated through EMG measurements, is used for the control of the Agile Eye mechanism.…”

Development of a New Robotic Ankle Rehabilitation Platform for Hemiplegic Patients after Stroke

“…Rutgers University developed a 6-DOF ankle rehabilitation robot “Rutgers ankle” based on a Stewart platform driven by pneumatic actuation, where a 6-DOF force sensor was used to provide force and torque feedback generated between the patient's foot and the foot pedal [5]. Liu et al announced a 3-RSS/S parallel robotic platform associated with a virtual training environment, which employed servo motor to drive its parallel links [6]. Meng et al constructed a parallel structure ankle rehabilitation robot, where the patient's leg is fixed to the base of the robot; therefore, the robot can drive the patient's foot to generate relative movement using the ankle joint as the pivot center [7].…”

Parallel Robot for Lower Limb Rehabilitation Exercises

“…To develop the robotic devices, first the motor learning and motor adaption of healthy people should be investigated; and then the neurologically injured patients can be rehabilitated with respect to the obtained results [ 22 , 23 ]. Therapeutic exercises can vary from range of motion, active assistive isotonic, isometric, isokinetic, and manual exercises [ 24 – 26 ].…”