Abstract
For the problem of actuator-integrated fault estimation (FE) and fault tolerant control (FTC) for the electric power steering (EPS) system of a forklift, firstly, a dynamic model of a forklift EPS system with actuator faults was established; then, an integrated FE and FTC design was proposed. The nonlinear unknown input observer (NUIO) was proposed to estimate the system states and actuator faults, and an adaptive sliding mode FTC system was constructed based on it. The gain of the observer and controller is obtained by H∞ optimization and one-step linear matrix inequality (LMI) formula operation in order to realize the overall optimal design of an FTC system. Finally, the experimental results show that when actuator failure occurs, the proposed integrated FE and FTC were more accurate than the decentralized design to estimate the system states and the actuator faults. The proposed fault-tolerant controller can more effectively restore the power assist performance of the steering power motor in case of failure and effectively ensure the safety and reliability of the forklift EPS system.
Highlights
Power Steering System of Forklift.As a transport tool, the forklift plays a very important role in cargo moving in ports, workshops, logistics warehouses, airports, and other fields
In the last few years, various types of observers and controllers have been used for actuator fault estimation and fault tolerant control, such as an integrated FE and FTC design for Lipschitz nonlinear systems subject to uncertainty, disturbance, and actuator/sensor fault
For forklift electric power steering (EPS) systems affected by bounded disturbance and actuator faults, a rankFor forklift EPS systems affected by bounded disturbance and actuator faults, a rankfree nonlinear unknown input observer (NUIO) algorithm is proposed to estimate the system state and fault simultaneously, free NUIO algorithm is proposed to estimate the system state and fault simultaneously, and an adaptive sliding mode FTC controller is constructed by using the obtained estimates
Summary
In the last few years, various types of observers and controllers have been used for actuator fault estimation and fault tolerant control, such as an integrated FE and FTC design for Lipschitz nonlinear systems subject to uncertainty, disturbance, and actuator/sensor fault. An integrated robust active FTC design based on linear matrix inequality (LMI) is proposed for a class of nonlinear systems with actuator failures [10]. Ijaz et al proposed a new adaptive integral sliding mode based on the FTC strategy for the actuator faults and failure compensation problem of a class of Lipschitz nonlinear systems. The nonlinear adaptive integral SMC and control allocation scheme are introduced to compensate the unknown disturbance and uncertainty caused by actuator failure and fault estimation.
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