Position Sensor-less Control for LOM based on Double Power Sliding Mode Observer with Third-order Generalized Integrator

In this paper, a double power sliding mode observer (DPSMO) is developed to estimate piston stroke of a linear oscillatory machine (LOM) to achieve robust sensor-less control. The DPSMO integrates the double power reaching law (DPRL) with an integral sliding mode surface. Both DPRL and integral sliding mode surface enhance the convergence rate of the sliding state, reduce the steady-state errors, and minimize the chattering phenomenon effectively. Furthermore, a third-order generalized integrator (TOGI) is introduced to address the integral saturation issue by effective elimination of the inherent DC components. The proposed method has been designed, assessed, and validated by full comparison with existing methods. Finally, the simulation and experimental results have confirmed its superiority over conventional methods.