Adaptive Backlash Inverse Augmented Virtual Decomposition Control of a Hydraulic Manipulator

In addition to the inherent strong nonlinearities associated with hydraulic systems, the use of mechanical drives (gears) in hydraulic applications (e.g., in hydraulic rotary actuators) introduces additional nonlinearities in the form of backlash. Thus, confronting these traditional hydraulic nonlinearities as well as the non-smooth backlash nonlinearity requires special considerations. This work designs a virtual decomposition control (VDC) controller, a subsytems-based nonlinear model-based controller, to combat the heavy hydraulic non-linearities in a hydraulic manipulator and effectively control it. For the first time, a VDC controller is designed to compensate for a non-smooth nonlinearity (backlash), which has never been modelled in the dynamic equations of all existing VDC works. While it is not presented herein, stability of the resulting controller can be mathematically proven based on the L2 and L∞ Lebesgue spaces. Obtained experimental results indicated the capability of the combined VDC algorithm and the adaptive backlash inverse scheme improves system’s position tracking performance compared to traditional Proportional-Integral-Derivative (PID) controller.