Page 26 - Read Online

Zhang et al. Intell. Robot. 2025, 5(2), 333-54 I http://dx.doi.org/10.20517/ir.2025.17 Page 351

Figure 14. Control input in the case of NFTSMC. NFTSMC: Non-singular fast terminal sliding mode controller.

in a finite time frame. The robustness of this method to unknown bounded external perturbations advances
and also solves the singularity problem and chattering phenomenon that often plague conventional slip-mode
control systems.

ThestabilityoftheentiresystemissubstantiatedthroughtheapplicationofLyapunovstabilitytheory,providing
a robust theoretical underpinning for the control framework. Simulation outcomes corroborate the efficacy
and resilience of the proposed control framework, demonstrating its adaptability to variations in reference
trajectories in response to safe mode settings and its capacity to maintain smooth operation with minimal
chattering during modal transitions.

Whilst the current control framework has exhibited promising results, there exist realms for further refine-
ment and development. One limitation highlighted in this discourse is the scheme’s sensitivity to the ini-
tial state of the system. Future research endeavors will concentrate on mitigating this issue by incorporating
fixed-time control strategies that can accommodate system model uncertainty. This will be instrumental in
enhancing the robustness of the exoskeleton system, particularly in unpredictable real-world scenarios where
initial conditions may exhibit significant variability. Another avenue for future inquiry is the enhancement
of the motion-dependent switching function. Although the current function permits smooth modal transi-
tions, there is potential to further optimize this function to respond more dynamically to alterations in patient
movement and external conditions. This could entail the integration of sophisticated sensor technologies and
machine learning algorithms to anticipate and adapt to patient requirements in real time. Furthermore, the
integration of haptic feedback and virtual reality technologies into the exoskeleton system could engender a
more immersive and engaging training experience for patients. This would not only augment the efficacy of
the rehabilitation process but also bolster patient adherence to the training regimen.