Data-driven adaptive integral terminal sliding mode control for uncertain SMA actuators with input saturation and prescribed performance

In this paper, finite-time consensus of double-integrator multi-agent systems is investigated. A new adaptive-terminal sliding mode control is proposed to satisfy the goal within a finite time by considering disturbances and input saturation. The problem is solved for two cases. In the first case, the agents are subjected to disturbances with known upper bounds and input saturation parameters. For the case, the control inputs are designed based on a terminal sliding mode technique to achieve the consensus aim within the finite time as a summation of settling and reaching times. Then, a fast terminal sliding mode control is applied and the control inputs are modified to reduce the high dependency of reaching times to initial speeds. In the second case, the upper disturbance bounds are unknown. To handle this problem, the control laws are adopted by an adaptive-terminal sliding mode method. The upper bounds of disturbances are estimated in the finite time. In both cases, the maximum control efforts are adjusted to always be less than the saturation boundary by optional tuning parameters. The proposed methods efficiency is verified by numerical simulations.

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Data-driven model-free adaptive fractional-order sliding mode control for the SMA actuator with prescribed performance

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/09544062211059746 ◽

2022 ◽

pp. 095440622110597

Author(s):

Hongshuai Liu ◽

Lina Hao ◽

Mingfang Liu ◽

Zhirui Zhao

Keyword(s):

Sliding Mode Control ◽

Fractional Order ◽

Sliding Mode ◽

Data Driven ◽

Sliding Mode Controller ◽

Prescribed Performance ◽

Sma Actuators ◽

Mode Control ◽

Model Free ◽

Sma Actuator

In this paper, a novel data-driven model-free adaptive fractional-order sliding mode controller with prescribed performance is proposed for the shape memory alloy (SMA) actuator. Due to the strong asymmetric saturated hysteresis nonlinear characteristics of the SMA actuators, it is not easy to establish an accurate model and develop an effective controller. Therefore, we present a controller without using the model of the SMA actuators. In other words, the proposed controller depends merely on the input/output (I/O) data of the SMA actuators. To obtain the reasonable compensation for hysteresis, enhance the noise robustness of the controller, and reduce the chattering, a fractional-order sliding mode controller with memory characteristics is employed to improve the performance of the controller. In addition, the prescribed performance control (PPC) strategy is introduced in our work to guarantee the tracking errors converge to a sufficiently small boundary and the convergence rate is not less than a predetermined value which are significant and considerable in practical engineering applications of the SMA actuator. Finally, experiments are carried out, and results reveal the effectiveness and success of the proposed controller. Comparisons with the classical Proportional Integral Differential (PID), model-free adaptive control (MFAC), and model-free adaptive sliding mode control (MFAC-SMC) are also performed.

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