David Watt

High Performance Motion Tracking Control for Electronic Manufacturing

Motion control requirements in electronic manufacturing demand both higher speeds and greater precision to accommodate continuously shrinking part/feature sizes and higher densities. However, improving both performance criteria simultaneously is difficult because of resonances that are inherent to the underlying positioning systems. This paper presents an experimental study of a feedforward controller that was designed for a point-to-point motion control system on a modern and state of the art laser processing system for electronics manufacturing. We systematically apply model identification, inverse dynamics control, iterative refinement (to address modeling inaccuracies), and adaptive least mean square to achieve high speed trajectory tracking. The key innovations lie in using the identified model to generate the gradient descent used in the iterative learning control, encoding the result from the learning control in a finite impulse response filter and adapting the finite impulse response coefficients during operation using the least-mean-square update based on position, velocity, and acceleration feedforward signals. Experimental results are provided to show the efficacy of the proposed approach, a variation of which has been implemented on the production machine.

High-speed camera with real time processing for frequency domain imaging.

We describe a high-speed camera system for frequency domain imaging suitable for applications such as in vivo diffuse optical imaging and fluorescence lifetime imaging. 14-bit images are acquired at 2 gigapixels per second and analyzed with real-time pipeline processing using field programmable gate arrays (FPGAs). Performance of the camera system has been tested both for RF-modulated laser imaging in combination with a gain-modulated image intensifier and a simpler system based upon an LED light source. System amplitude and phase noise are measured and compared against theoretical expressions in the shot noise limit presented for different frequency domain configurations. We show the camera itself is capable of shot noise limited performance for amplitude and phase in as little as 3 ms, and when used in combination with the intensifier the noise levels are nearly shot noise limited. The best phase noise in a single pixel is 0.04 degrees for a 1 s integration time.

High Speed Processing of Frequency Domain Images

We are developing a system to process high frame rate frequency domain images using field programmable gate arrays. This has applications diffuse optical imaging or fluorescence lifetime imaging.

High-Speed Camera for Frequency Domain Imaging

We describe a high-speed camera system for performing frequency domain imaging with applications to photon migration imaging or fluorescence lifetime imaging. Field programmable gate arrays allow processing images up to 2 gigapixels per second.

High Speed Frequency Domain Camera

We are developing a system for high bandwidth frequency domain imaging using a high-speed camera together with field programmable gate array processing. Data processing rates are up to 2 gigapixels per second.