For the forklift equipped with electrical sensors, a fault tolerant control (FTC) strategy is proposed. First, considering the uncertainty of forklift cargo and the external output disturbance, the equivalent sensor fault model of forklift is constructed. Then, a sliding mode observer (SMO) with adaptive regulation law is proposed to solve the problem that some fault reconstruction methods demand the upper bound of faults. Based on the fault value reconstructed by SMO, a sliding mode fault-tolerant controller is designed. It can realize active FTC of typical sensor faults of forklift in the presence of uncertainties and output disturbance. Finally, experiment is given to verify the effectiveness of the proposed FTC strategy. INDEX TERMS Forklift, sensor fault diagnosis, multi-sensor fault reconstruction, fault tolerant control.
For the problem of multiple sensor faults in the automated guided forklift (AGF), an equivalent model with system faults and disturbances is established. To detect multiple sensor faults in the AGF, a sliding mode observer (SMO) is proposed. It introduces a fault estimation algorithm that is designed by the fault residual and the residual is only sensitive to sensor faults which means that the SMO is robust to unknown input disturbances. On the other side, it can also judge the faulty sensor according to the feature vector of different sensors. To judge the type of sensor faults accurately, a mathematical model of sensor fault characteristics is established and it can provide a foundation for choosing appropriate fault-tolerant output compensation measures. Then an active fault-tolerant control method based on state feedback is proposed. It can restore the control system to normal and maintain the stability of the control system. Finally, experiments are given to verify the effectiveness of the proposed fault-tolerant control strategy.
Considering the movement of synthetic center of gravity of forklift caused by the cargo moving, a vehicle model including the cargo weight and its moving speed is established. Based on this model, a lateral stability controller with uncertain parameters is proposed. The proposed controller controls the four-wheel steering (4WS) forklift by analyzing feedback compensation angle which can realize fast tracking of the ideal yaw rate and sideslip angle with high robustness, solve the problem of insufficient lateral stability caused by the movement of cargo under the turning condition and improve the working efficiency of forklift. Under the operation conditions of a step input and double-lane-change (DLC) maneuver, the built forklift model is simulated and proved to be valid. Combined with the vehicle test, it is verified that the above control strategy can optimize the dynamic response indexes such as yaw rate and sideslip angle of the forklift and improve the impact of cargo moving on the lateral stability of forklift.INDEX TERMS Forklift, stability, cargo moving, sliding mode control, system with uncertain parameters.
For the problem of multiple sensor fault detection and reconstruction in the forklift fault-tolerant control system, a sliding mode observer (SMO) with adaptive regulation law is proposed. Based on the three-degree-of-freedom (3-DOF) model of forklift, a linear state equation with output disturbance is designed as its equivalent sensor fault model. The sensor fault is converted into an actuator fault by defining an auxiliary state variable as an output signal filter. Then the SMO-based method of sensor fault detection and reconstruction is given. Without knowing the upper bound of an unknown fault, an adaptive sliding mode observer (ASMO) can also be effective through the adaptive algorithm. Finally, experimental results further verify the effectiveness of the method, and provide a foundation for forklift fault-tolerant control.
Introduction: As an important transportation, the research on the control strategy of forklift has not been widely carried out. Objectives: This article proposes a turning slip regulation control strategy, which includes the improved electronic differential velocity control and turning slip regulation control, to track the optimal slip ratio. Methods: First, combined with the basic structure and characteristics of dual-wheel-independent-drive electric forklift, the vehicle model, Ackermann–Jeantand steering model, tire-ground model, and tire model of the driving wheel are established respectively. Second, according to these models, an improved electronic differential control strategy considering the influence of vertical load on tire force is proposed and it can reasonably allocate the driving torque of the two driving wheels of electric forklift. Moreover, the optimal slip ratio is given out and the turning slip regulation control strategy, which can track the optimal slip ratio of electric forklift under the conditions of different road surfaces is designed. Results: The simulation result and vehicle test show that the control strategy can optimize the slip ratio of electric forklift and greatly improve the stability of electric forklift. Conclusion: The turning slip regulation control strategy can be implemented on the TFC35 forklift to improve the safety and stability.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.