This paper discusses the quasi-synchronous tracking control of multiple electro-hydraulic actuators (MEHA) with load disturbances and parametric uncertainties. Each electro-hydraulic actuator (EHA) has a third-order nonlinear dynamics in the presence of unknown lumped uncertainties resulting from some uncertain hydraulic parameters and external load. Firstly, the isomorphic MEHA system is constructed which extracts the nominal model from the lumped uncertainties. Then, an adaptive quasi-synchronization controller is designed such that each cylinder position of the MEHA system tracks the desired trajectory in a collaborative manner. To compensate the lumped uncertainties of the MEHA system, adaptive laws are constructed and the resultant quasi-synchronization controller guarantees that all the closed-loop signals and the estimate errors are uniformly ultimately bounded. Finally, the effectiveness of the proposed control method is verified by simulation and experimental results.

In electro-hydraulic system (EHS), uncertain nonlinearities such as some hydraulic parametric uncertainties and external load disturbance often degrade the output dynamic performance. To address this problem, a prescribed performance constraint (PPC) control method is adopted in EHS to restrict the tracking position error of the cylinder position to a prescribed accuracy and guarantee the dynamic and steady position response in a required boundedness under these uncertain nonlinearities. Furthermore, a dynamic surface is designed to avoid the explosion of complexity due to the repeatedly calculated differentiations of the virtual control variables derived in backstepping. The effectiveness of the proposed controller has been verified by a comparative results.