Time delay compensation and disturbance effect reduction on a magnetic levitation system based on a modified Smith predictor control scheme

The position control of magnetic levitation systems is complicated by several factors. These include hardware-induced delays, such as sensor response times and signal processing latency, as well as persistent disturbances like voltage and the effect of gravity. In addition, the inherently unstable dynamic behavior of the system further challenges the effectiveness of control strategies. In this article, we study how to overcome the challenges of controlling a magnetic levitation system. This system is inherently nonlinear and unstable, which makes its control particularly challenging. Besides, the presence of time delays and external disturbances further complicates the control process. To tackle these issues, control strategies based on the Smith predictor approach – which is well-suited for handling time-delay systems – have been developed. However, since the traditional Smith predictor has limited ability to reject disturbances, several modifications have been introduced in recent studies to improve its disturbance rejection performance. A control approach employing a novel modified Smith predictor has been introduced to address the challenges of controlling unstable systems with inherent time delays. As part of the design, two controllers are introduced. The first one handles the set-point tracking, whereas the second is specifically tailored for disturbance rejection. Finally, the proposed control technique SP − H is implemented on a real magnetic levitation platform, and its performance is compared with other control schemes. The experimental results demonstrate the effectiveness of the proposed approach and its superior performance, showing excellent set-point tracking and strong disturbance rejection capabilities.