Quantitative Feedback Theory Velocity Control of a Single-rod Pump-controlled Actuator Using a Novel Flow Compensation Circuit

This paper employs the quantitative feedback theory (QFT) to design a robust fixed-gain linear velocity controller for a newly developed single-rod pump-controlled actuator. The actuator operates in four quadrants, with a load force becoming resistive or assistive alternatively. The controller also satisfies tracking, stability and sensitivity specifications in the presence of a wide range of system parametric uncertainties. Its performance is examined on an instrumented John Deere JD-48 backhoe. The experimental results show that the controller can maintain the actuator velocity within an acceptable response envelope, despite variation in load mass as high as 163 kg and the hydraulic circuit switching between operating quadrants.