Mode Control In Order Research Articles

Nonlinear Control of an Electromagnetic System Based on Exact Linearization and Sliding Mode Control#

The present research project aims to apply two nonlinear control tools: exact linearization and sliding mode control, in the position control of a nonlinear system comprising an iron ball and an electromagnetic coil. Exact linearization (EL) has been used to generate a desired level in the current, and then the current acts like a current source for the electromagnetic coil considering that the system can be separated in a mechanical and electrical subsystem. Notably, we will need to follow this desired current because that current is required to maintain the ball's levitation. For that reason, we will use the sliding mode control in order to force the real current to track the desired current. Lyapunov stability will be used to validate the convergence of this tracking. The satisfactory performance of the controlled system has been verified by simulations in Matlab. However, the implementation, not shown in this paper, was performed using the DSP TMS 320LF2407, which is a powerful digital signal processor.

On digital high-gain and sliding-mode control

This paper is on the analysis and design of sampled-data high-gain control and sliding-mode control systems. In continuous high-gain control, it is usually true that the higher the gains, the more effective the system uncertainties may be suppressed. When implemented digitally, however, there are limits to the feedback gains without causing instability.This paper analyses high-gain,sampled-data,systems utilizing the results of the singular perturbation theory. The system can be decomposed into fast and slow subsystems under high gain feedback. It is shown how the fast subsystem goes unstable when the gains get high enough due to the sampling effect. With reasonable approximations, a set of simple stability criteria is derived relating the feedback gains to the sampling period and other factors. It is also shown that control chattering, which is typical in variable structure systems with sliding mode, also happens in high-gain control systems when the gains exceed or are close to the critical values. Moreover, since the behaviour of a variable structure system with sliding mode is very close to that of a high-gain system, the design issue of a digital slidingmode control system is also explored in this paper. From the similarity between the two control techniques, the stability criteria for high-gain systems are shown to be applicable to the design of digital sliding mode control in order to guarantee stability and avoid chattering.

Adaptive sliding mode control for variable structure systems with constraint control input

In this paper, the problems in sliding mode control systems with constraint control input are described, and then we utilize selecting a switching surface with an integrator to solve this problem and to derive a bound for the existence of sliding motion. Additionally, we propose an adaptive sliding mode controller in order to reduce settling time and also maintain the sliding motion in a larger bound. Finally, an illustrative example is given to demonstrate the effect of proposed controller.