A new robust discrete-time sliding mode control design for systems with time-varying delays on state and input and unknown unmatched parameter uncertainties

In discrete-time systems, instead of having a hyperplane as in the continuous case, there is a countable set of points comprising a so-called lattice; and the surface on which these sliding points lie is the latticewise hyperplane. In this paper the concept of multivariable discrete-time sliding mode is clarified and new sufficient conditions for the existence of the sliding mode are presented. A new control design using the properties of discrete sliding is proposed, and the behavior of the system in the sliding mode is studied. Furthermore, the stabilization of discrete-time systems and an optimal sliding lattice are considered. [S0022-0434(00)02804-5]

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Discrete Sliding Mode Speed Control of Induction Motor Using Time-Varying Switching Line

Electronics ◽

10.3390/electronics9010185 ◽

2020 ◽

Vol 9 (1) ◽

pp. 185 ◽

Cited By ~ 1

Author(s):

Grzegorz Tarchała ◽

Teresa Orłowska-Kowalska

Keyword(s):

Sliding Mode Control ◽

Induction Motor ◽

Discrete Time ◽

Control Method ◽

Sliding Mode ◽

Power Converter ◽

Discrete Version ◽

Time Varying ◽

Mode Control ◽

Switching Line

Sliding mode control (SMC) of electric drives constitutes a very popular control method for nonlinear multivariable and time-varying systems, e.g., induction motor (IM) drives. Nowadays, IM are the most popular electrical machines (EM) applied in many industrial applications as motion control devices, including electrical and hybrid vehicles. Nowadays, the control systems of EM are mostly realized using digital techniques (microprocessors and microcontrollers). Therefore, all control algorithms should be discretized or the whole control system should be designed in the discrete-time domain. This paper deals with a discrete-time sliding mode control (DSMC) for IM drives. The discrete algorithms for sliding mode control of the motor speed and rotor flux are derived in detail and next tested in simulation research. The simulation tests include the discrete nature of the power converter supplying the IM and present excellent performance of the developed control structure. To obtain the rotor speed regulation invariant to external disturbances, like load torque or inertia, especially during the reaching phase of the switching line, the discrete version of a time-varying switching line was introduced. It is shown that the assumed dynamics of the IM flux and speed is achieved and the proposed control algorithm can be realized using commonly available microcontrollers. The paper is illustrated with comprehensive simulation results for 1.5 kW IM drive, which are verified by experimental tests.

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Multiloop state-dependent nonlinear time-varying sliding mode control of unmanned small-scale helicopter

Proceedings of the Institution of Mechanical Engineers Part G Journal of Aerospace Engineering ◽

10.1177/0954410019872116 ◽

2019 ◽

Vol 234 (3) ◽

pp. 585-606 ◽

Cited By ~ 1

Author(s):

Sinan Ozcan ◽

Metin U Salamci ◽

Volkan Nalbantoglu

Keyword(s):

Sliding Mode Control ◽

Sliding Mode ◽

Operating Conditions ◽

Small Scale ◽

Time Varying ◽

Parameter Uncertainties ◽

Time Step ◽

Mode Control ◽

State Dependent ◽

Improved Performance

Time delays, parameter uncertainties, and disturbances are the fundamental problems that hinder the stability and reduce dramatically the tracking performance of dynamical systems. In this paper, a new state-dependent nonlinear time-varying sliding mode control autopilot structure is proposed to cope with these dynamical and environmental complexities for an unmanned helicopter. The presented technique is based on freezing the nonlinear system equations on each time step and designing a controller using the frozen system model at this time step. The proposed method offers an improved performance in the presence of major disturbances and parameter uncertainties by adapting itself to possible dynamical varieties without a need of trimming the system on different operating conditions. Unlike the existing linear cascade autopilot structure, this study also proposes a nonlinear cascade state-dependent coefficient helicopter autopilot structure consisting of four separate nonlinear sub-systems. The proposed method is tested through the real time and PC-based simulations. To show the performance of the proposed robust method, it is also bench-marked against a linear sliding control control in PC-based simulations.

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