Overcoming Gear Backlash With Flexible Shaft Using Disturbance Observer

Abstract

The presence of backlash in gears with a flexible shaft is a challenging non-linearity that can cause vibration and noise, due to unstable torque, in the system which lead the system to unpleasant behavior and damage. In this paper, we are going to estimate the backlash angle to compensate the input torque to a simulated two-inertia system and overcome the torque instability in the system. The backlash non-linearity will be represented by the rigorous model proposed by Nordin et al. (2001) and carefully installed in an accurate simulation model, which gives the most effective platform for validation of controllers. Ignoring external loads, we are going to use Disturbance Observer (DO) to approximately estimate the internal backlash angle under flexible shaft condition. The estimated disturbance will be compensated and fed back to a torque controller to operate the system and overcome the unstable torque due to backlash. The simulation results showed that the driver motor torque accurately tracked the reference, in contrast with PID controller results without DO. However, the backlash estimation is not accurate, but it is synchronized with actual backlash angle. Therefore, in our further investigation, we are going to apply this scheme in our actual system and compare between simulation and experimental results using our new machine proposed in Shino (2022); Samadouny et al. (2023). Moreover, we will modify this scheme to estimate the backlash angle accurately.