Backstepping sliding-mode control for active suspension system matching mechanical elastic wheel with uncertainties

For the purpose of anti-puncture and lightweight, a new type of mechanical elastic wheel (MEW) is constructed. However, the large radial stiffness of MEW has a negative effect on ride comfort. To make up for the disadvantage, this paper proposes a novel control strategy consisting of backstepping control and integral sliding-mode control, considering the uncertainties of active suspension and MEW. First, an active suspension system matching MEW is established, discussing the impact of uncertainties. The nonlinear radial characteristic of MEW is fitted based on the previous experiment results. Then, in order to derive ideal motions, an ideal suspension system combining sky-hook and ground-hook damping control is introduced. Next, ignoring the nonlinear characteristics and external random disturbance, a backstepping controller is designed to track ideal variables. Combined with the backstepping control law, an integral sliding-mode control strategy is given, further taking parameter uncertainty and external disturbance into account. To tackle chattering problem, an adaptive state variable matrix is applied. By using Lyapunov stability theory, the whole scheme proves to be robust and convergent. Finally, co-simulations with Carsim and MATLAB/Simulink are carried out. By analyzing the simulation results, it can be concluded that the vehicle adopting backstepping sliding-mode control performs best, with excellent real-time performance and robustness.

Order-reduced-model based integral sliding mode control of a heavy-duty hydraulic manipulator with disturbances estimation

A sliding mode control method is adapted to the trajectory tracking and positioning control of a heavy-duty hydraulic manipulator in this article, which shows high performance with the drive of hydraulic proportional valve. The dynamic model of the system is established, the complexity of which is reduced based on the singular perturbation theory to simplify the analysis and the online calculation of the control variable. The extended state observer is developed in the control loop to estimate the real-time disturbances including the parameter uncertainties and load changes of the system. The integral sliding mode control law is designed combining the extended state observer, and the stability of the system is proved theoretically. The experimental results on a heavy-duty hydraulic manipulator show that the proposed control method has high dynamic tracking performance and positioning accuracy, and the proposed extended state observer can effectively resist disturbances.

Robust Global Synchronization of a Hyperchaotic System with Wide Parameter Space via Integral Sliding Mode Control Technique

The inherent property of invariance to structural and parametric uncertainties in sliding mode control makes it an attractive control strategy for chaotic dynamics control. This property can effectively constrain the chaotic property of sensitive dependence on initial conditions. In this paper, the trajectories of two identical four-dimensional hyperchaotic systems with fully-known parameters are globally synchronized using the integral sliding mode control technique. Based on the exponential reaching law and the Lyapunov stability principle, the problem of synchronizing the trajectories of the two systems was reduced to the control objective of asymptotically stabilizing the synchronization error state dynamics of the coupled systems in the sense of Lyapunov. To verify the effectiveness of the control laws, the model was numerically tested on a hyperchaotic system with a wide parameter space in a master-slave configuration. The parameters of the hyperchaotic system were subsequently varied to evolve a topologically non-equivalent hyperchaotic system that was identically coupled. In both cases, the modeled ISM control laws globally synchronized the dynamics of the coupled systems after transient times, which sufficiently proved the invariance property of the ISMC. This study offers an elegant technique for the modeling of an ISMC for hyperchaotic coupling systems. As an open problem, this synchronization technique holds promises for applications in robot motion control, chaos-based secure communication system design, and other sensitive nonlinear system control.

A novel dynamic integral sliding mode control for power electronic converters

The key characteristics of the sliding mode control (SMC) are the ability to manage unmodeled dynamics with rapid response and the inherent robustness of parametric differences, making it an appropriate choice for the control of power electronic converters. However, its drawback of changing switching frequency causes critical electro-magnetic compatibility and switching power loss issues. This paper addresses the problem by proposing a dynamic integral sliding mode control for power converters having fixed switching frequency. A special hardware test rig is developed and tested under unregulated 12.5-22.5 V input and 30 V output. The experimental findings indicate excellent controller efficiency under wide range of loads and uncertain input voltage conditions. In addition, the findings indicate that the closed-loop system is robust to sudden differences in load conditions. This technique provides an improvement of [Formula: see text]% in the rise time, [Formula: see text]% in the settling time and [Formula: see text]% in robustness of the controller as compared to conventional controllers. Furthermore, the comparison with the existing fixed-frequency sliding mode control techniques is presented in a tabular form.