Sahbi Boubaker^1,2,*, Salim Hadj Said³, Souad Kamel¹, Habib Dimassi³

CMC-Computers, Materials & Continua, Vol.85, No.3, pp. 5703-5721, 2025, DOI:10.32604/cmc.2025.069047 - 23 October 2025

Abstract Accurate trajectory tracking in lower-limb exoskeletons is challenged by the nonlinear, time-varying dynamics of human-robot interaction, limited sensor availability, and unknown external disturbances. This study proposes a novel control strategy that combines flatness-based control with two cascaded observers: a high-gain observer to estimate unmeasured joint velocities, and a nonlinear disturbance observer to reconstruct external torque disturbances in real time. These estimates are integrated into the control law to enable robust, state-feedback-based trajectory tracking. The approach is validated through simulation scenarios involving partial state measurements and abrupt external torque perturbations, reflecting realistic rehabilitation conditions. Results confirm More >

Mohammad Soleimani Amiri¹, Sahbi Boubaker^2,3,*, Rizauddin Ramli^4,*, Souad Kamel²

CMES-Computer Modeling in Engineering & Sciences, Vol.144, No.3, pp. 3113-3133, 2025, DOI:10.32604/cmes.2025.069167 - 30 September 2025

Abstract Disability is defined as a condition that makes it difficult for a person to perform certain vital activities. In recent years, the integration of the concepts of intelligence in solving various problems for disabled persons has become more frequent. However, controlling an exoskeleton for rehabilitation presents challenges due to their non-linear characteristics and external disturbances caused by the structure itself or the patient wearing the exoskeleton. To remedy these problems, this paper presents a novel adaptive control strategy for upper-limb rehabilitation exoskeletons, addressing the challenges of nonlinear dynamics and external disturbances. The proposed controller integrated… More >

Lang Qin¹, Zhengrui Jiang¹, Xueshu Xing², Xiao Wang¹, Yaohua Yin², Yuhui Zhou², Zhiqin He^1,*

CMC-Computers, Materials & Continua, Vol.83, No.3, pp. 5279-5298, 2025, DOI:10.32604/cmc.2025.063358 - 19 May 2025

Abstract In permanent magnet synchronous motor (PMSM) control, the jitter problem affects the system performance, so a novel reaching law is proposed to construct a non-singular fast terminal sliding mode controller (NFTSMC) to reduce the jitter. To enhance the immunity of the system, a disturbance observer is designed to observe and compensate for the disturbance to the sliding mode controller. In addition, considering that the controller parameters are difficult to adjust, and the traditional zebra optimization algorithm (ZOA) is prone to converge prematurely and fall into local optimum when solving the optimal solution, the improved zebra… More >

Xiangfei Li, Yang Yin, Yang Zhou, Wenchang Liu, Kaihui Zhao^*

Energy Engineering, Vol.120, No.2, pp. 277-297, 2023, DOI:10.32604/ee.2023.022461 - 29 November 2022

Abstract This paper presents a novel non-singular fast terminal sliding mode control (NFTSMC) based on the deep flux weakening switching point tracking method in order to improve the control performance of permanent interior magnet synchronous motor (IPMSM) drive systems. The mathematical model of flux weakening (FW) control is established, and the deep flux weakening switching point is calculated accurately by analyzing the relationship between the torque curve and voltage decline curve. Next, a second-order NFTSMC is designed for the speed loop controller to ensure that the system converges to the equilibrium state in finite time. Then, More > Graphic Abstract

Bin Zhang, Boqiang Wei^*

Energy Engineering, Vol.119, No.3, pp. 1197-1218, 2022, DOI:10.32604/ee.2022.018411 - 31 March 2022

Abstract The non-cascade permanent magnet synchronous motor control system has the advantages of simple structure and less adjustable parameters, but the non-cascade structure needs to solve the problem of over-current protection. In this paper, a current constrained control method is used to limit the starting current to a safe range. At the same time, to ensure the robustness and rapidity of the system, a super twist current constraint controller (CCSTA) is generated by combining super twist algorithm (STA) with current constraint control; Considering the diversity of internal and external disturbances, a functional disturbance observer (FDOB) is More >