Nanopositioning (NP) stages are used to perform precise nanoscale manufacturing and measurement. Friction bearings (such as roller bearings) are a promising way to lower the cost of NP stages while still preserving their range of motion and versatility in a clean room environment. However, these bearings have prolonged settling times due to non-linear nanoscale friction effects. Current methods using feed forward or feedback control are only robust within a small range of friction behavior and rely on complex control loops to be effective. Vibration-Assisted Nanopositioning (VAN) Stage technology promises to overcome these limitations through a new friction-compensation strategy that will enable friction bearing NP stages to deliver on their cost effectiveness potential.
Independent dithering actuator keeps control simple
By introducing a new independent high-frequency vibration actuator to the NP stage, a dither force can be applied directly to the frictional points of contact to eliminate nonlinear effects. Special design elements isolate this dithering from the body of the stage, and any lingering vibrations can be completely compensated by using a simple repetitive controller on the main stage actuator. Further optimizations can control the frequency, amplitude, and on time of the dither to best suit compensatory needs. Preliminary simulation results on VAN show greater robustness and stability to a variety of friction parameters, enabling more versatile friction bearing nanopositioning stage deployments.
- Nonlinearity compensation in friction bearing nanopositioning stages
- Simpler control schemes in nanopositioning stages
- Greater robustness and stability to varying friction parameters
- Reduces control complexity and costs through simple, independent dithering actuator
- Improved stage settling time and accuracy