Fixed-Time Control of the Lifting Axis of a CNC Machine Using a Permanent Magnet Synchronous Motor and a Fixed-Time Nonlinear Observer

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dc.contributor.authorCholahan, Varin
dc.contributor.authorTangsrirat, Worapong
dc.contributor.authorPukkalanun, Tattaya
dc.date.accessioned2026-08-06T10:55:57Z
dc.date.available2026-08-06T10:55:57Z
dc.date.issued2026-07-01
dc.description.abstractThis paper introduces an adaptive fixed-time position controller (AFxTPC) designed for the lifting axis servo mechanism of a computer numerical control (CNC) plasma machine. It integrates a permanent magnet synchronous motor, gearbox, and ball screw into a unified electromechanical model. The proposed AFxTPC combines a fixed-time terminal sliding surface function with adaptive fixed-time sliding mode control to achieve fixed-time convergence, precise tracking, and robustness in the presence of parameter uncertainties. A specially designed reaching law guarantees accurate trajectory tracking, while the fixed-time terminal sliding surface function effectively minimizes chattering near the sliding manifold. Importantly, a novel fixed-time nonlinear disturbance observer is developed to simultaneously estimate the unmeasured system states and lumped disturbances in real time within a guaranteed initial-state-independent settling time. These estimated values are explicitly fed back into controller for active disturbance compensation. The stability of the overall closed-loop system is rigorously established using Lyapunov stability theory. Simulation results demonstrate that the proposed observer-based controller achieves superior performance compared with conventional proportional–integral–derivative (PID) and standard sliding mode controllers. It exhibits zero steady-state error, reduced overshoot, minimal chattering, and strong robustness over a wide range of operating conditions.
dc.identifier.citationTechnologies, 14(7), 2026
dc.identifier.doi10.3390/technologies14070381
dc.identifier.issn22277080
dc.identifier.other2-s2.0-105045869240
dc.identifier.urihttps://dspace.kmitl.ac.th/handle/123456789/18216
dc.sourceTechnologies
dc.subjectadaptive sliding mode control
dc.subjectCNC servo system
dc.subjectdisturbance observer
dc.subjectfixed-time control
dc.subjectpermanent magnet synchronous motor (PMSM)
dc.subjectrobust nonlinear control
dc.titleFixed-Time Control of the Lifting Axis of a CNC Machine Using a Permanent Magnet Synchronous Motor and a Fixed-Time Nonlinear Observer
dc.typeArticle

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