The automation of multi degree of freedom hydraulic crane by using Virtual Decomposition Control

In this paper heavy-duty hydraulic crane automation is addressed by applying the Virtual Decomposition Control (VDC) approach. The VDC approach allows the control problem of the entire system to be converted into the control problem of individual components, i.e. subsystems while rigorously guaranteeing the stability of the entire system without jeopardizing the control performance. The experimental results demonstrate that the VDC approach is applicable to robust and high performance control of low-cost hydraulic multi Degree of Freedom (DOF) applications, in which the controller is challenged by a significant number of different nonlinearities and parameter uncertainties. When a VDC controller was compared with a conventional PID controller, approximately 7 times lower piston position maximum error was achieved. Moreover, a VDC controller was given roughly the same control accuracy with low, medium and high velocity trajectory references without any additional tuning, whereas the performance of the PID controller significantly changed between different velocity trajectories. The achieved results with the VDC controller are comparable with the reported state-of-the-art studies on nonlinear model-based control of hydraulic multi DOF applications.