Three-Stage Design Analysis and Multicriteria Optimization of a Parallel Ankle Rehabilitation Robot Using Genetic Algorithm

Abstract

This paper describes the design analysis and optimization of a novel 3-degrees of freedom (DOF) wearable parallel robot developed for ankle rehabilitation treatments. To address the challenges arising from the use of a parallel mechanism, flexible actuators, and the constraints imposed by the ankle rehabilitation treatment, a complete robot design analysis is performed. Three design stages of the robot, namely, kinematic design, actuation design, and structural design are identified and investigated, and, in the process, six important performance objectives are identified which are vital to achieve design goals. Initially, the optimization is performed by considering only a single objective. Further analysis revealed that some of these objectives are conflicting, and hence these are required to be simultaneously optimized. To investigate a further improvement in the optimal values of design objectives, a preference-based approach and evolutionary-algorithm-based nondominated sorting algorithm (NSGA II) are adapted to the present design optimization problem. Results from NSGA II are compared with the results obtained from the single objective optimization and preference-based optimization approaches. It is found that NSGA II is able to provide better design solutions and is adequate to optimize all of the objective functions concurrently. Finally, a fuzzy-based ranking method has been devised and implemented in order to select the final design solution from the set of nondominated solutions obtained through NSGA II. The proposed design analysis of parallel robots together with the multiobjective optimization and subsequent fuzzy-based ranking can be generalized with modest efforts for the development of all of the classes of parallel robots.Note to Practitioners-Design of parallel robotic mechanisms present many challenges. This paper attempts to formulate and solve these problems in the pretext of a parallel mechanism designed for ankle joint physical therapy. The problems include the parallel mechanism itself and intrinsically compliant or flexible actuators used to power the parallel robot. In order to address these issues, a complete design analysis of the parallel ankle rehabilitation robot was carried out. The design analysis was divided into three stages, namely, kinematic design, actuation design, and structural design. A NSGA II algorithm was used to optimize the Manuscript six performance objectives. The method proposed in this work can be used for the development of all categories of parallel robots with minor adaptations.Index Terms-Nondominated genetic algorithm, parallel robots, robot design optimization, wearable ankle rehabilitation robot.

Reconfigurable workspace and torque capacity of a compliant ankle rehabilitation robot (CARR)

“…However, these configurations were only preliminarily selected and further optimization should be involved to enhance the kinematic and dynamic performance. Jamwal, Hussain [23] proposed a three-stage analysis techniques, including kinematic design, actuation design, and structural design, to solve the issues in the pretext of a parallel mechanism designed for ankle therapy. This analysis method can be used for the optimization of the CARR with minor adaptations.…”

Single joint robotic orthoses for gait rehabilitation: An educational technical review

“…A quasi-passive knee exoskeleton for human locomotion augmentation has been proposed recently (50). The quasipassive exoskeleton comprises a stiffness control module on the thigh segment and a pulley on the shank segment.…”

“…During the swing phase, a torsional spring-damper control provides toe clearance. A control scheme based on finite-state machine has also been designed for the quasi-passive knee exoskeleton in order to engage the assistance spring (50). The controller identifies the states of the gait cycle using in-sole sensors that indicate the heel and toe contacts with the ground (50).…”

EEG-modulated robotic rehabilitation system for upper extremity

“…In the past few years, many research institutes have developed robotic rehabilitation systems [3,4]. Depending on the patient's condition, programmable levels of assistance can be provided by a robot [5,6]. Moreover, the patient's rehabilitation process can be tracked and suggestions to the therapists can be made whenever necessary.…”