Automation1: Industry-leading Laser Scan Head Material Processing Performance

The Benefits of Controlling a Laser Scan Head and Servo Stages from a Single Motion Controller

Many laser machine builders are experienced in building systems that incorporate both laser scan heads and direct- or ballscrew-driven servo stages. Usually, machine component selection is driven by consideration of laser-material interaction. (For example; a laser scan head is often selected when a higher throughput is desired.)

However, laser scan heads often use f-theta optics that can affect beam quality (and therefore part quality & process performance). ?

Fortunately for machine builders, there is a way to manage these tradeoffs and build a machine that optimizes process throughput while maintaining part quality: Aerotech’s high-performance laser scan heads and controls.

Aeroech's Automation1 uses a single controller for both scan head and servo motion control - and offers numerous controller features for precision process control.

High-Performance Laser Scan Heads and Controls

No matter how good the controls are, high performance will not be possible without exceptional mechanical hardware. The award-winning AGV-XPO High-Dynamic Laser Scan Head? - Aerotech’s highest performance laser scan head -is a two-axis laser scan head designed to minimize the tradeoff between speed and precision.

It's high-efficiency motors enable rapid acceleration profiles, while ultra-high resolution position feedback and optimized structural dynamics provide excellent part-profile tracking with minimal following error.?AGV-XPO scan heads provide an order of magnitude improvement to in-position jitter when compared to Aerotech’s own AGV-HP 2D scan head – a specification that translates to improved tracking capabilities.

The AGV-XPO’s control architecture is unique in that the amplifiers and servo control loops are not contained in the laser scan head. Instead, they are located remotely in the?Automation1 GL4 Galvo Laser Scan Head Linear Drive. This architecture improves system performance in ways traditional scan heads with integrated controls cannot match. Removing the electronic heat source from the scan head ensures consistent performance over time – a must for any production material processing application. The GL4 uses linear amplifiers, which are the highest performance amplifier technology for driving galvanometric motors and provide improved velocity control and position stability.

A Single Controller for Scan Head and Servo Motion Control

Once you have selected mechanical hardware that is up to the task, you need a control system to match. The?Automation1 iSMC Intelligent Software-Based Motion Controller?is a central motion engine capable of generating a single stream of motion control positions over the?HyperWire??Motion Control Communication Bus. The HyperWire bus runs at 2 gigabits per second (Gbps) with a position update rate of 100 kHz. This means that the Automation-iSMC controller can generate and communicate 100,000 position command points per second for the laser scan head axes and 20,000 position command points per second for the servo axes. Over HyperWire, the Automation1-GL4 receives the 100 kHz stream of points and interpolates the number of points to 200 kHz for use in the 200 kHz two-axis laser scan head servo controller. A variety of Automation1 servo motor drives can be used, and each receives the 20 kHz stream of position command points over HyperWire and uses them directly in the drive’s servo control loop. The trajectory points are 64-bit double-precision floating point values, and the drive-to-drive jitter is capable of being < 1 nanosecond, even after adding 16 total axes on a single HyperWire port.

Simply put, no superior motion control technology exists for coordinating the motion of precision laser scan heads and servo axes.

Using a single controller drives the highest performance coordination of laser scan heads with servo axes for the most demanding laser processing applications. Aerotech’s Automation1 controller platform is unique in that it enables not only a single configuration and programming environment for scan heads and servo axes, but it also enables higher performing systems due to some of the unique controller features addressed in the next section.

Controller Features for Precision Process Control

Automation1 has several controller features for those building precision laser material processing machines:

• Automation1 provides extensive encoder feedback tuning and servo tuning tools for optimizing axes’ performance.

• Error mapping - both 1D and 2D calibration tables – can be constructed and loaded into the Automation1 controller. Aerotech provides special services for error mapping of servo axes.?However, machine builders can manage this process on their own. Similarly,?laser scan head calibration is often handled by machine builders and the process is simplified with tools like Aerotech’s?GalvoCFC – Galvo Calibration File Converter?

• ?Infinite Field of View?(IFOV) feature enables users to directly program a part (or series of parts) that extend past the laser scan head’s field of view (XY-motion constraints) with a single XY trajectory. IFOV pre-processes a larger motion path and designates the higher speed portion of that path to the laser scan head. IFOV designates the lower speed portion to the servo axes. This ensures that the scan head is always working within its field of view. Because IFOV eliminates step and scan motion, the laser remains on for a larger percentage of time and therefore increases process throughput.? Another unique advantage of using IFOV is that the actual servo stage position is known by the Automation1 GL4 laser scan head controller immediately prior to the servo control loop. This allows the laser scan head to compensate for dynamic position errors in real time. Approaching combined scan head and servo stage motion in this manner helps to manage servo stage position errors that can be orders of magnitude larger than the scan head position errors.

• Position Synchronized Output (PSO)?tool provides precision laser machine builders with a flexible toolset for managing laser-material interactions. For pulsed lasers, the pulse spacing can be managed by tracking actual distance traveled and generating a firing event based on a fixed or variable distance. A firing event typically creates a physical change in state for a PSO output pin on a specified Automation1 servo motor drive. How this output functions is configurable. The output can be held “on” for a specific amount of time, a specific waveform can be generated or a series of pulses can be generated. In addition, an analog output can be modified with each firing event.??

IFOV, PSO and laser output control functions are all powerful features in the Automation1 motion control platform, and are even more powerful when used together.

The final result is a world-class precision automation machine that delivers all the advantages of the Automation Motion Development Kit (MDK), including the Studio application, the Automation1 APIs and the Automation1 MachineApps Windows-based custom HMI tool.

These tools make Automation1 a single-motion control environment for machine builders who want to lead their industry in precision laser material processing applications.??