Adaptive gain super twisting algorithm to control a knee exoskeleton disturbed by unknown bounds
- PDF / 3,005,154 Bytes
- 16 Pages / 595.276 x 790.866 pts Page_size
- 13 Downloads / 159 Views
Adaptive gain super twisting algorithm to control a knee exoskeleton disturbed by unknown bounds Seyed Mehdi Rakhtala1 Received: 20 January 2020 / Revised: 24 August 2020 / Accepted: 12 September 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Knee exoskeletons as wearable robots have been increasingly aimed to assist elderly and disabled people to increase their movement abilities through flexion/extension execution of the knee. In this paper, a robust controller was suggested for a new knee joint orthosis. The system is integrated with the orthosis and the human shank and has a nonlinear dynamic model. This paper presents a novel robust controller of an active orthosis for rehabilitation due to no prior knowledge on the dynamical model and unknown the flexion/extension movements as disturbances, an adaptive gain super-twisting algorithm is used to control the knee joint. It is needed to this strategy to cope with the nonlinear nature of the knee exoskeleton with disturbance and model uncertainties that is bounded with unknown bounds. The stability analysis was proven by the Lyapunov approach. Keywords Exoskeleton/actuated orthosis · Adaptive gain super-twisting algorithm · Dynamic modelling · Lyapunov stability · Adaptive PID
1 Introduction Exoskeletons and wearable robots are defined as mechatronic devices that are worn by an operator and fit closely to the body to increase the ability to achieve daily activities. The exoskeletons assist people in routine tasks such as (standingup, sitting-down, transport weighty loads, climbing stairs, walking, etc.) and medical application such as rehabilitation of dependent persons. An exoskeleton is worn on a part of the body (arms, knee, pelvis, etc.) or upper or lower limbs of human [1]. The first passive wearable robot was developed in 1935 by G.L. Cobb as a Patent. The exoskeletons included mechanical device acting on the upper/lower human’s body and are developed to be comfortable for the wearer with its movements [2]. In the Tokyo University of Agriculture and Technology, an exoskeleton was designed to help people for framing work [3]. Berkeley University in 2006 and 2007 has designed a Berkeley lower limb exoskeleton named the BLEEX as one of the most famous that eligible its wearer to carry heavy
B 1
Seyed Mehdi Rakhtala [email protected] Faculty of Engineering, Department of Electrical Engineering, Golestan University, Gorgan, Iran
loads [4]. A military application of these robots is Hercules that has been used to increase the performances of soldiers [5]. A knee joint orthosis at Salford University was developed by Costa et al. [6]. This robot has five DoF for the ankle, knee and hip for each leg. Nowadays, this equipment’s are made for different applications such as medical, military applications.
1.1 Literature review for knee exoskeleton Knee exoskeleton is mechatronic equipment that is included of a mechanical part, sensor, actuator, and controller. In this literature, the exoskeletons are being surveyed in actuator type of D
Data Loading...
