Model-based sub-nano positioning control systems
|Project members:||ir. J.R. van Hulzen (Jan), prof.dr.ir. P.M.J. Van den Hof (Paul), prof.dr.ir. J. van Eijk, |
|Keywords:||Robotics and mechatronics, Model-based control|
|Sponsored by:||Delft University of Technology|
A common tool for inspection and manipulation in the nano and sub-nanometer range is the scanning probe microscope (SPM). In most SPM applications the required range is in the micrometer range with a high accuracy scanning area of 50-100 nm2. Recently SPM’s having the ability to scan at video rate have started to emerge. For these applications high bandwidth motion control is required.
The goal of the project is to research actuation for position and motion control under extreme demands on bandwidth and accuracy.
Historically probe positioning is controlled using piezo electric actuators. Piezo actuators have high mechanical stiffness and can operate at the required accuracy and bandwidth. They do however exhibit hysteresis type non-linear behavior, thermal drift and creep. Using feedback we can address these problems. Non-linear control schemes like Preisach model inversion and feedback linearization have been proposed. However, due to their complexity and reliance on exact models they are difficult to implement in high bandwidth applications. Our aim is to provide bandwidth and stability by using simple control in combination with load balancing. By matching actuator and load we can use the driven load to damp the resonant modes of the actuator dynamics enabling high bandwidth without the need to provide damping electrically.