Adaptive Terminal Sliding-Mode Control for Speed Tracking of Multiple High Speed Train
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Date
2022-04
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Addis Ababa University
Abstract
In today‟s world, the railway transportation entered into the era of high speed. Which means the
concern becomes more of to travel faster and safer. High speed trains are a train with a maximum
operating speed of more than 200 km/h. Automatic train operation system is an operational
safety enhancement device used to help automate the operation of the high speed trains. This
system does its controlling function based on controllers which is embedded on it. But, due to
some influencing factors which reduce the performance of the controllers which embedded on
ATO like; parameter uncertainties, unknown model parameters, actuator effectiveness loss,
coupler effect and external disturbance, until know there is a limitation in controllers to attain
finite time convergence of the tracking error to the equilibrium point rather than achieving
asymptotic convergence, that means stability within finite time is not guaranteed.
In real time operation of high speed trains (HSTs), stability within finite time interval is desired
instead of the asymptotic stability, as it is more physically realizable than concerning infinite
time. In this paper, adaptive terminal sliding-mode control scheme was developed for finite time
stable speed tracking control for high speed trains with unknown parameters of a model,
parameters uncertainties, actuator effectiveness losses, coupler effect and external disturbance. In
this paper the train system is modeled as a multi-point mass model and considered the in-train
forces between the adjacent cars which are the effect of couplers. To attain stability within in a
finite time terminal sliding-mode control is proposed and introduced for multiple high speed
train system that drives the dynamical system of a tracking error to the predesigned sliding
surface within defined time and thereafter sustain a sliding motion on it. For online estimation of
unknown parameters of the model and the actuator fault compensation term adaptive technique is
designed and cooperates with a terminal sliding-mode control. Saturation function is used to
eliminate the chattering problem caused due to the terminal sliding mode control. Lyapunov
theory is used to demonstrate the stability of a closed-loop train system. Lastly, to demonstrate a
performance of the controller Matlab/Simulink environment is used. Finally, the system response
settles within 3.134ms and zero steady state error is attained. So, the main objective of the paper,
stability in finite time is achieved with good tracking accuracy. To realize the strong robustness
of the proposed controller, its performance was demonstrated for different scenarios and
obtained good results.
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Keywords
high-speed trains, multi-point mass model, tracking control, finite time stability, adaptive control, terminal sliding mode surface, actuator faults