Visual sensing and visual servo control

Objective: 

The need for high precision and robust motion control is wide spread in areas dealing with micro and nano scale phenomena where ultra precision motion control devices are extensively used in advanced instrumentations and modern fabrication processes requiring the highest precision. In the micro world, the governing mechanics are highly uncertain where gravity is no longer the dominant force and temperature fluctuations of proportions that are harmless in the macro world, can be detrimental causing structural drift, sensor drift, and surface tension variations. Therefore, manipulation of material and objects in the micro world requires schemes based on feedback information that directly and precisely conveys the objective task at hand. Our lab’s research is focusing on multi-axis and multi-object motion measurement and visual servo control in nanometer resolution.

Figure 1: Setup for the Lateral Sampled White Light Interferometry method

Figure 2: Integrated visual servoed 3D multi-object alignment system

Figure 3:  3D alignment error in x-y-z.

Ongoing Project:

Six-axis visual sensing and visual servo control for nanometer resolution by using the lateral sampled white light interferometry (L-SWLI, as shown in Figure 1) method and pattern matching method.

Finished Project:

1.  An Ultra Precision Six-Axis Visual Servo Control System, a tracking of 1 um circle motion with visual feedback control was performed as show in Figure 2.
2.  Visual Servo Control Achieving Nanometer Resolution in X-Y-Z.
3.  Visually Servoed 3D Alignment of Multiple Objects(system setup as show in Figure 3) with Sub-Nanometer Precision.

Facilities:

1. Leica DMLM microscope and interferometers (20x and 50x ).
2. PI Nanocube XYZ Piezo Nanopositioning System.
3. PI High-Speed Objective Nanofocusing/Scanning Z-Drives with Direct Metrology.
4. PI LISA (Linear Stage Actuators) high-speed nanopositioner.
5. Photometric CoolSnap Monochrome CCD Camera.

Publications:

[1] J. Kim, S.K. Kuo, C.H. Menq, “An Ultra Precision Six-Axis Visual Servo Control System,” IEEE Transactions on Robotics Volume 21,  Issue 5,  Oct. 2005 Page(s):985 - 993.
[2] J. Kim, C.H. Menq, “Direct Visual Servo Control Achieving Nanometer Resolution in X-Y-Z,”  to appear in IEEE Transactions on Robotics.
[3] J. Kim, C.H. Menq, “Visually Servoed 3D Alignment of Multiple Objects with Sub-Nanometer Precision,” to appear in IEEE Transactions on Nanotechnology.