Researchers at the University of Aberdeen have developed a new vibration control scheme that increases the positioning bandwidth of precision positioning systems such as nanopositioning platforms. The enables a higher bandwidth capability without any intrusive mechanical modifications required to existing parts. The control strategy can be used in a variety of positioning systems such as hard disc drives, robots, satellite booms, overhead cranes, windmill towers, 3D-printing, high-density data storage devices, and other micro and nanomanipulation and machining.

About the technology

Until now the only known method of increasing positioning bandwidth (cut-off frequency) of precision positioning systems has been to change the mechanical design that places the dominant first resonant mode at a higher frequency. This is however time-consuming and often impractical due to material property limitations and motion range requirements.

The new vibration control scheme shifts the resonant mode through a controller-based method; this enables a higher bandwidth capability without any intrusive mechanical modifications to existing parts.

The main attractive qualities of the vibration control scheme are:

1. Substantial increase in the positioning bandwidth (as much as 40% of the original resonant frequency of the system) without the necessity of any mechanical modifications.

2. High gain and phase margins guaranteeing stability.

3. Parametric design and availability of optimization schemes with respect to user-defined performance indices.

4. Easy analogue implementation with tuning capability.

The optimization algorithms have been theoretically proved and experimentally validated for this system. An application-specific optimization of controller parameters for best system performance is possible.

The performance enhancement is shown in the graph below: the blue line shows the frequency response of an open-loop nanopositioner with a dominant resonant peak that limits the achievable positioning bandwidth; the black line shows the response of a nanopositioner with generic closed-loop control strategy, where the resonant peak is visibly damped but the positioning bandwidth is still less than that the dominant open-loop resonant mode; finally, the red line shows the response of the same nanopositioner with this new control strategy: The resonant peak is not only damped, but additionally delivers a substantially higher bandwidth (by ~40%) than the first resonant peak of the platform.

Response of control systems

Applications and benefits

Key Benefits:

  • Widely applicable to all systems where speed of operation (motion / positioning / pick and place) is limited by the first undamped natural frequency
  • No mechanical alteration of existing systems required
  • Simple to implement via an inexpensive and Tuneable analog Circuit
  • Eliminates resonance-induced vibrations
  • Increases bandwidth of existing positioning systems without needing mechanical alterations to the design

Applications:

  • Nanopositioners used in Atomic Force Microscopes / Scanning Probe Microscopes etc
  • Robotic manipulators and medical robots
  • Nanomachining and nanolithography equipment
  • 3D printing
  • Hard disk drives
IP status

UK Priority filed, patent pending.

Contact for further information

Dr Miguel Rey, Research & Innovation
Email: Miguel Rey
Tel: +44(0) 1224 274157