Figure 1: Inertia matching means matching the inertia of the scanner motor assembly to the inertia of the load. This yields the highest scanner motor performance.
General Scanning has developed a new approach to digital servo control as part of its Lightning Digital Scanner technology platform. This new digital servo driver addresses the quest for higher system performance in a number of ways. First, the signal-to-noise ratio has been significantly improved through the use of a 16-bit bus design for low noise and high accuracy. The new design uses a DSP processor to run sophisticated control algorithms, and multiple filters for frequency-response shaping. Lastly, it provides an interface that enables the driver to support a sophisticated software toolset that automates tuning and documents key performance parameters. General Scanning offers the TuneMaster Software Toolset for this purpose, reducing development time, lowering production costs, improving product support, and maintaining “like-new” system performance over a product’s service life.

Software Toolset

Figure 2: The basic optical scanner consists of a servo driver and a scanner motor with position detector for feedback. Tuning the servo loop with analog or digital servo drivers traditionally has been a time-consuming manual procedure.
TuneMaster consists of three interactive modules that provide tools for product development, production, and field support. One of the main challenges in servo control is tune development or balancing scanner system speed and accuracy for a given application. Today, engineers use either an oscilloscope to observe optical scanner performance in the time-domain, or a signal analyzer to perform sophisticated tuning in the frequency domain. Engineers observe the results and adjust the controls to shape the response of the system. In either case, scanner tuning is done using an intermediate indicator that is limited to a specific type of motion.

The approach taken by TuneMaster allows engineers to tune the optical scanner in the application domain, or in other words, the system is tuned while running its actual application, such as marking, welding, or cutting. Additional equipment that yields intermediate indicators of system performance is no longer required because the tuning process is software-controlled and automatic. As a result, the resulting development time for the application tune can be reduced up to 90%.

Tuning the servo with software rather than using external equipment also makes it easier to set up multiple servos for OEM manufacturers. Using the MatchTune Generator Module, the operator downloads a specific tune for a given application from the archive and automatically adjusts the system’s optical scanner set to the desired quality and throughput based on the original application requirements captured by the TuneMaster Creator module.

In addition to automated scanner optimization, full documentation is retained for quality assurance and traceability. For each system, the original TuneMaster, the resulting MatchTune, system performance at the time of production, and serial numbers are recorded in a production database and onboard the Lightning servo driver. This capability also eases field repairs and upgrades because TuneMaster’s Support Toolbox Module lets technicians replace only the failed component — a motor or a mirror — and restore the system to like-new performance through its automated software-tuning routines.

Ongoing maintenance or re-tuning a system to maintain optimal performance also can be automated. By linking the system based on Lightning technology to a computer, TuneMaster software can re-tune the system to match the original performance specification. Click the retune button on the Support Toolbox Module GUI and system performance is re-optimized in less than a minute.

Lightning Digital Scanner Technology and TuneMaster software are examples of the ongoing development of digital optical scanning solutions, bringing in a new era of digital hardware paired with advanced software tools that provide cost-effective, improved control of optical scanners and the systems that depend on them.

This article was written by Amit Shahar, market development manager, at General Scanning (GSI Group), llerica, MA. For more information, contact Mr. Shahar at This email address is being protected from spambots. You need JavaScript enabled to view it., or visit

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