Integrated mechatronic design of precision and energy saving electro-hydraulic systems

Lower cost, higher control performance and significantly less energy consumption are the goals for the design of any industrial systems including electro-hydraulics. The paper presents an integrated mechatronic design approach – seamless integration of advanced control techniques with novel hardware reconfiguration/re-design – as one of the tools to achieve these lofty goals simultaneously. The proposed integrated mechatronic design philosophy will be illustrated through recent research on the precision and energy saving control of electro-hydraulic systems. Specifically, instead of the traditional four-way valves, a unique configuration of five independently controlled poppet type cartridge valves is used as an example of hardware redesigns for the control of hydraulic systems. Such a hardware redesign not only enables decoupled controls of the meter-in and meter-out flows but also precise control of the cross-port regeneration flow for significant energy-savings. In addition, the much faster responses of the poppet type cartridge valves also provide the hardware capability of completely overcoming the performance limiting sandwiched deadband control problems associated with the traditional four-way proportional directional valves. Coordinated advanced adaptive robust controls are subsequently developed to effectively handle the increased complexity of system level controls and the difficulty of precisely controlling each individual cartridge valve due to the lack of accurate flow models. Comparative experimental results obtained have demonstrated that the proposed low cost programmable valves not only achieve significant energy saving but also higher control performance.