335 ISSN 0146-4116, Automatic Control and Computer Sciences, 2020, Vol. 54, No. 4, pp. 335–345. © Allerton Press, Inc., 2020. Chattering-Free Adaptive Finite-Time Sliding Mode Control for Trajectory Tracking of MEMS Gyroscope A. S. S. Abadi a, *, P. A. Hosseinabadi b , N. B. Soin c , and S. Mekhilef b, d a Department of Electrical Engineering, Yazd University, Yazd, Iran b Power Electronics and Renewable Energy Research Laboratory (PEARL) Department of Electrical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur, 50603 Malaysia c Department of Electrical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur, 50603 Malaysia d School of Software and Electrical Engineering, Swinburne, Victoria, Australia *e-mail: a.soltanisharif@stu.yazd.ac.ir Received September 16, 2019; revised October 14, 2019; accepted December 18, 2019 Abstract—One of the inevitable problems with real-time control systems is the presence of the uncer- tainties and external disturbances. The existence of these uncertainties in the fabrication processes of the MEMS Gyroscope devices can deeply impact the performance of the devices. In this paper, five adaptive finite time robust control methods are employed based on SMC method for a Micro-Electro- Mechanical System (MEMS) Gyroscope with mismatched uncertainties and external disturbances to achieve trajectory tracking goal. A new Stepping SMC method is proposed in this study to improve some deficiencies of conventional and existing methods including Simple SMC, Classical SMC, Cubic SMC, and Hexagonal SMC. The upper bound of mismatched uncertainties is estimated in finite time and their estimation is utilized in the control inputs for all five control methods. The elim- ination of chattering phenomenon is considered in this paper. The system finite time stability proof is obtained using Lyapunov stability theory. The numerical simulation is performed in Simulink/MATLAB for the MEMS gyroscope system to demonstrate the effectiveness of our proposed control method, Stepping SMC, compared with four other methods. To make an extensive comparison among results, the performance criterion, Integral of the square value (ISV), is used. Keywords: chattering-free, finite-time, SMC, adaptive, MEMS, gyroscope DOI: 10.3103/S0146411620040021 1. INTRODUCTION The existence of the uncertainties in most real-time systems is one of the inevitable issues in the mod- eling of these systems. Uncertainties can be due to the existence of unmodeled dynamics, measurement errors, and parametric uncertainties. Uncertainties effects are much higher when the system is exposed to the disturbances. Different methods have been presented to deal with these disturbances and uncertain- ties, such as estimating the upper bound of them and using their estimations in the controller design by utilizing adaptive control concept [1–9]. In [10], an adaptive control concept has been incorporated with a robust H∞ method to ensure asymptotic system stability. In [11], a trajectory tracking control scheme has been proposed based-on an adaptive scheme for wheeled mobile robots. Furthermore, SMC is a robust popular non-linear control scheme. It is popular for its low sensitivity towards external disturbances, and parametric uncertainties or variations in the system [12–20]. It has been applied in [13] for networked control systems by multiple data packet losses. The studied class of the systems has been only subjected to the matched uncertainties and external disturbances. Indeed, they have not dealt with mismatched disturbances and uncertainties, which are more present in the real-time con- trol systems. In [21], SMC scheme has been utilized to provide a robust trajectory tracking controller for an agricultural tractor with the influence of slip. One of the problems with these control efforts (especially with conventional SMC methods) for dealing with uncertainties is the occurrence of the undesirable chattering phenomenon. Many control efforts have been made to reduce the effect of this destructive phenomenon [22–24], which reduces the useful life of