Sliding-mode variable structure control for complex automatic systems: a survey

<abstract> <p>Automatic systems (ASs) can automatically control the work of controlled objects without unattended participation. They have been extensively used in industry, agriculture, automobiles, robots and other fields in recent years. However, the performance of the controller cannot meet the work requirements under complex environmental conditions. Therefore, improving the control performance is one of the difficult problems that automated systems should solve. Sliding-mode variable structure control has the advantages of fast response, insensitivity to uncertainty and interference and easy implementation; thus, it has been extensively used in the field of complex control systems. This article analyses and explains the research status of motors, microgrids, switched systems, aviation guidance, robots, mechanical systems, automobiles and unmanned aerial vehicles (UAVs) and prospects for the application of sliding-mode variable structure control in complex ASs.</p> </abstract>

Optimal Quick-Response Variable Structure Control for Highly Efficient Single-Phase Sine-Wave Inverters

This paper puts forward an optimal quick-response variable structure control with a single-phase sine-wave inverter application, which keeps harmonic distortion as low as possible under various conditions of loading. Our proposed solution gives an improvement in architecture in which a quick-response variable structure control (QRVSC) is combined with a brain storm optimization (BSO) algorithm. Notwithstanding the intrinsic resilience of a typical VSC with respect to changes in plant parameters and loading disruptions, the system state convergence towards zero normally proceeds at an infinitely long-time asymptotically, and chattering behavior frequently takes place. The QRVSC for ensuring speedy limited-time convergence with the system state to the balancing point is devised, whilst the BSO will be employed to appropriately regulate the parametric gains in the QRVSC for the elimination of chattering phenomena. From the mix of both a QRVSC together with a BSO, a low total harmonic distortion (THD) as well as a high dynamic response across different types of loading is generated by a closed-loop inverter. The proposed solution is implemented on a practicable single-phase sine-wave inverter under the control of a TI DSP (Texas Instruments Digital Signal Processor). It has experimentally shown the simulation findings as well as the mathematical theoretical analysis, displaying that both quick transient reaction as well as stable performance could be obtained. The proposed solution successfully inhibits voltage harmonics in compliance with IEEE 519-2014’s stringent standard of limiting THD values to less than 5%.

AUTO LOAD-LEVELLING CONTROL OF A LARGE SPRAYER CHASSIS USING THE SLIDING MODE METHOD

When a sprayer travels on a ramp or a rough road, the load exerted on each wheel changes. If an unbalanced wheel load is maintained for long periods of time, the wheels may slip, the sprayer’s manoeuvrability is affected, and a rollover accident may occur. In this study, the air suspension of a self-propelled sprayer chassis was investigated, and the potential load imbalance conditions of the sprayer suspension were analysed. A mathematical model of the inflation/deflation of the suspension was established based on air nonlinear thermodynamics and vertical dynamics theory and a ¼-scale vertical dynamics model of the sprayer chassis was developed. A control strategy to balance the sprayer’s wheel load was developed. Considering the nonlinear characteristics of the air suspension, a sliding mode variable structure control method was used to balance the wheel load. Simulation experiments were conducted under different working conditions. The simulation results showed that the sliding mode variable structure control provided good control response and precision. The proposed auto load-levelling controller was tested under different working conditions, including different roll and pitch angles and navigating a rough road; the controller successfully changed the load on each spring to ensure that the sprung mass of the suspension was equal and the wheel load was balanced. The results of this study provide reference information for auto load-levelling control of large sprayers.