Control Design of a De-Weighting Upper Limb Exoskeleton

Abstract

One of the most common problems in humans is a muscle fatigue. Exoskeletons are known as one of the solution to deal with human muscle fatigue. However, several issues related to the development of exoskeletons for such a case have been identified. One of these is the control mechanism. Thus, the objective of this paper is to investigate development of a control strategy for the upper-limb exoskeleton. In this paper, a new control mechanism for an upper-limb exoskeleton is proposed. A fuzzy-based PD controller and PID are used in the proposed control mechanism, and a comparative assessment of the performance of both controllers is made. The results show that the control mechanism with fuzzy-based PD controller performs better than the PID controller in terms of trajectory tracking accuracy and control torque analysis.

Modelling of extended de-weight fuzzy control for an upper-limb exoskeleton

“…Table 4, the RMS and MAE values for the extended de-weight fuzzy were lesser as compared to fuzzy-PD. This indicates that the combination of fuzzy-based PD and de-weight fuzzy provides a more stable and robust system as compared to the previous study [1,2]. This observation could be due to the algorithm of the extended de-weight fuzzy itself, in which the value of the actual movements and the error is considered and subsequently added as inputs to the fuzzy.…”

“…7. A detailed description of the control design is provided in [1,2]. The proposed controller has been previously tested on humans with different strength [1].…”

“…The exoskeleton is one example of an assistive technological innovation. Nowadays, the use of an exoskeleton is not limited to assisting or augmenting human performance [1][2][3][4]. In fact, the exoskeleton has been identified as one of the solutions in dealing with muscle fatigue in humans [5][6][7].…”

Innovative Metaheuristic Optimization Approach with a Bi-Triad for Rehabilitation Exoskeletons

“…For the second, simplified biomechanical models of rigid bodies are used (the upper limb uses a simplified model of 7 degrees of freedom (DOF) and it assumes 3 DOF for the shoulder, 2 DOF for the elbow and 2 DOF for the wrist [1,8,22,23]). Regarding the third, industrial controllers are commonly used in trajectory tracking [2,7,[22][23][24][25][26].…”

“…The use of a standard industrial controller through a human-robot interface proved to be feasible in application (therapeutic routines adaptable to users through different modes of operation). However, it is feasible to improve the controller by including adaptive in-line control techniques (attention to disturbances during therapeutic routines) [1,7,24].…”