Adaptive motion stage reaction force cancellation with an active vibration isolation system

Precision machines with an internal motion stage typically feature a force frame or a balance mass to prevent actuation forces from reaching the sensitive parts of the machine. In some cases, the use of a balance mass or force frame might not be desired due to the added volume and/or mass. Here, we propose to use an active vibration isolation system to cancel the reaction forces generated by the motion stage, while also isolating a sensitive payload from floor vibrations. A feedforward controller is designed to transmit the reaction forces to the floor. This feedforward controller is designed by solving the non-linear equations of motion, and is implemented adaptively to track the changes of the system using the filtered error method. For experimental validation, an existing active vibration isolation setup is extended with a flexure-based motion stage. Validation of the proposed method shows that the power of the sensitive payload acceleration in the 1–200 Hz frequency band decreased by 3-4 orders of magnitude, depending on the direction, when compared to the case where the controllers of the AVIS are turned off. Furthermore, the peak tracking error of the stage decreases by a factor of 10. In the 15–100 Hz frequency band, almost all measurable floor vibrations are cancelled in the sensitive payload acceleration.