Adaptive sliding mode control of a magnetic levitation three-point bending device

This paper presents a non-contact three-point bending device based on magnetic levitation technology, in which a specimen can be bent while being levitated. As the levitated object needs to withstand an increasing bending load in levitated state, this requires the control system to have a strong robustness. Therefore, a centralized sliding mode controller (CSMC) was proposed for the levitation. Furthermore, based on CSMC, an adaptive centralized sliding mode controller with the bending load as scheduling variable (ACSMC), which is the novelty of this paper, were proposed to deal with the disturbance caused by the bending load. Simulation results demonstrated that ACSMC has good robustness to three typical bending loads, i.e., ramp load, sine load, step load. Finally, experiments were conducted and experiment results demonstrated that ACSMC allows the device to withstand ramp bending load, sine bending load and step bending load up to 50 N.