An Ultra Precision Six-Axis Visual Servo Control System

A real-time visual measurement of six-degree-of-freedom motion with nanometer precision.

The Need

Conventional microscopic visual feedback systems have limited out-of-plane measurement resolution in the micrometer range, and conventional interferometry systems are inherently not real-time sensors. When dealing with dimensions of sub-micrometer range, small pre-calibration errors, e.g. non-orthogonal transducer axes, can lead to erroneous results, especially in the cases where rotational motion is necessary. Errors such as thermal expansion and sensor drift can be even more critical and will attribute to system variance with respect to the object coordinate frame. A niche for a measurement device that can measure in the nanometer range, as well as in 3D exists.

The Technology

The Ohio State University researchers, led by Dr. Chia-Hsiang Menq, developed a visual measurement device that provides the full pose of multiple 3D micro objects with under ten nanometer precision in x-y-z. The six-degree -of-freedom motion of each object is measured from a single image. No scanning is necessary to obtain 'out-of-plane' motion parameters. This allows real-time positioning and alignment of micro-objects. Therefore, it can serve as a compact motion sensor and can be employed to achieve direct metrology and visual servo control in the object's space with nanometer resolution. This measurement technique can be applied to achieve automatic positioning and engagement in imaging and manipulation of micro objects at micro and nano scales. Applications include dynamic alignment of micro parts, assembly of micro-optical components, assembly of micro mechanical components, assembly of micro sensors and so forth.

Commercial Application

  • Motion sensing
  • Research and development


  • Imaging and manipulation of objects at the micro and nano scales.
  • Many researchers and practitioners believe that multi-scale 3D devices whose components measure down to nanometers will have a much greater application range than microelectromechanical systems (MEMS) in many industries including medicine, communications, defense, aerospace, consumer products, and many more.

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