Real-time fuzzy-feedforward controller design by bacterial foraging optimization for an electrohydraulic system

High power-to-weight ratio rugged electrohydraulic systems are extensively used for land tilling, harvesting, construction and various industrial control operations. Flow, friction and valve deadband nonlinearities of these systems make the controller design quite challenging, especially for meeting fast and precise motion tracking requirements. For such a system, a bacterial foraging optimization, or BFO, has been employed with a simple swarming method proposed here to design a real-time controller. With a fuzzy voltage compensating the flow-related continuous nonlinearities, a feedforward voltage has been employed to cater for known external loading and discontinuous internal nonlinearities due to the valve deadband and cylinder stiction. Acceptability of the optimized controller has been demonstrated by testing the performances for square, trapezoidal and triangular demands for the piston position variation with time.