Extended State Observer Based Control for a Mechanical Drive System with Unmatched External Disturbance

In this study, a mechanical drive system is modeled by a simple mass-spring-damper system, and the system is used for designing robust controllers to compensate for an external disturbance that does not fulfill the matching condition. A corresponding test rig with two electrical motors and coupling elements has been built for experimental verification. Two different control strategies are proposed for the given control task, the Extended State Observer Based Control (ESOBC) and the Sliding Mode Control (SMC) in combination with the extended state observer (ESO). Both controllers are compared by simulation where the SMC achieves a better performance. However, when applying the controllers to the real test rig, the experiment using the SMC shows chattering and the ESOBC achieves better results.