Before revision: This virtual state (sum of unknown part of model dynamics and external disturbances, usually denoted as a "total disturbance" ) is estimated online with an extended state observer and used in the control signal in order to decouple the system from the actual perturbation acting on the plant.
After revision: or "generalized disturbance"This virtual state (sum of unknown part of model dynamics and external disturbances, usually denoted as a "total disturbance" ) is estimated online with an extended state observer and used in the control signal in order to decouple the system from the actual perturbation acting on the plant.