A review on the mechanical design elements of ankle rehabilitation robot

Abstract

Ankle rehabilitation robots are developed to enhance ankle strength, flexibility and proprioception after injury and to promote motor learning and ankle plasticity in patients with drop foot. This article reviews the design elements that have been incorporated into the existing robots, for example, backdrivability, safety measures and type of actuation. It also discusses numerous challenges faced by engineers in designing this robot, including robot stability and its dynamic characteristics, universal evaluation criteria to assess end-user comfort, safety and training performance and the scientific basis on the optimal rehabilitation strategies to improve ankle condition. This article can serve as a reference to design robot with better stability and dynamic characteristics and good safety measures against internal and external events. It can also serve as a guideline for the engineers to report their designs and findings.

Design and Performance Evaluation of a Novel Wearable Parallel Mechanism for Ankle Rehabilitation

“…Thus, it is necessary to carry out the anatomical analysis before determining the configuration of the robot. As one of the most complicated joint in the human body, the HAC (Figure 1A) contains two anatomically separate joints, namely, the ankle joint and the subtalar joint (Dai and Zhao, 2004;Khalid et al, 2015). Specifically, the ankle joint consisting of the tibia, fibula and talus, is located above the subtalar joint which is formed by the talus inferiorly and the calcaneus superiorly (Dai and Zhao, 2004).…”

“…The rotation axis of the ankle joint (i.e., PL/DO) passes through the tips of the medial and lateral malleolus ( Figure 1B), and the orientation of IN/EV (i.e., the rotation axis of the subtalar joint) is approximated by the line between the superior point of the navicular and the posterolateral point of the calcaneus (Figure 1C; Dul and Johnson, 1985;Dettwyler et al, 2004). The combined motion of the ankle joint and the subtalar joint, as well as the rotation between the tibia and fibula contribute to the AD/AB (Khalid et al, 2015). In biology, the aforementioned skewed rotation axes produce rotational motion in all three orthogonal planes (i.e., sagittal, coronal, and transverse planes; Feuerbach et al, 1994).…”

Moving toward Soft Robotics: A Decade Review of the Design of Hand Exoskeletons

“…Generally, the control strategies of the hand exoskeletons can be divided into two categories: low-level and high-level control strategies. In the low-level control strategy, the controller addresses the physical parameters of the device such as force, torque and position [79]. It uses basic control loops for positioning or controlling force/torque based on the design parameters.…”

Toward Standardizing the Classification of Robotic Gait Rehabilitation Systems

“…Back-drivability: During rehabilitation exercises, it is possible that the patient suddenly loses control or the ability to move a limb, as well as any unexpected event. Therefore, if the system is not ready to cope quickly with the new situation, it may cause damage to the patient [104]. Moreover, the backdrivability allows the therapist to easily apply certain maneuvers, that is, back-drivability is the ability of the system to show low intrinsic endpoint impedance toward certain force sources [41], thus the patient does face an inertia that could delay the response of the system.…”