Disturbance Observer with Energy Reducing Filter

Disturbance rejection in a closed loop multi-actuator system. In some embodiments, a first disturbance observer (DOB) circuit is configured to inject a first disturbance rejection signal into an input control signal of a first stage of a multi-stage actuator. A second DOB circuit is configured to concurrently inject a second disturbance rejection signal into an input control signal of a second stage of the multi-stage actuator. Each of the first and second DOB circuits includes a band pass filter and an energy reducing filter. In some embodiments, the energy reducing filter has at least one notch filter and at least one anti-notch filter. In other embodiments, the energy reducing filter is a low-pass filter (LPF).