Research ArticleGA-optimized feedforward-PID tracking control for a rugged electrohydraulic system design

- A rugged cylinder and proportional valve have been used for their manufacturing ease, longer component life and energy efficiency.
- A feedforward controller has been used to compensate the hard nonlinearities of valve deadband and cylinder friction.
- No characterization experiments have been performed to design the feedforward controller.
- A real-coded GA has been used to optimize the feedforward and feedback controller parameters.
- The rugged system has provided performance comparable to a servosystem.

Rugged electrohydraulic systems are preferred for remote and harsh applications. Despite the low bandwidth, large deadband and flow nonlinearities in proportional valves valve and highly nonlinear friction in industry-grade cylinders that comprise rugged systems, their maintenance are much easier than very sophisticated and delicate servocontrol and servocylinder systems. With the target of making the easily maintainable system to perform comparably to a servosystem, a feedforward control has been designed here for compensating the nonlinearities. A PID feedback of the piston displacement has been employed in tandem for absorbing the unmodeled effects. All the controller parameters have been optimized by a real-coded genetic algorithm. The agreement between the achieved real-time responses for step and sinusoidal demands with those achieved by modern servosystems clearly establishes the acceptability of the controller design.