Laser Systems
Laser Process Automation — Analog Control Retrofit
Work performed as an employee of an aerospace manufacturer, shown as an example of the engineering rather than as client work. Process details and the employer are omitted deliberately.
Project Overview
A Class 4 laser cell ran entirely on manually entered process parameters. An operator set laser power and pulse repetition frequency by hand, which made results depend on who was running the machine that day. The cell also had no accurate as-built electrical documentation. The work brought the process parameters under automatic control and rebuilt the electrical and technical documentation from scratch.
Challenge
- •Laser power and pulse repetition frequency were set manually, so results varied between operators and between runs
- •No analog path existed between the robot controller and the laser control board, so the robot could not vary parameters along a path
- •Circuit diagrams did not match the installed hardware after an earlier controls change, leaving no accurate as-built records
- •No operating, troubleshooting, or maintenance documentation existed for the cell
Approach
- •Designed and built a voltage-controlled oscillator PCB that converts an analog control voltage into a laser pulse repetition frequency, giving the robot direct control of PRF
- •Added an analog output module to the robot controller and wired the full path: robot controller to PLC cabinet to VCO board to laser control board
- •Modified the PLC program to route and interlock the new control signals
- •Programmed the robot to vary power voltage and pulse frequency along the path under program control rather than by operator entry
- •Redrew the complete as-built electrical documentation in AutoCAD Electrical from the installed hardware
- •Wrote system documentation at three levels — operator, engineer, and maintenance — covering components, interconnects, and troubleshooting
Outcome
Process parameters are set by the program instead of by hand, and the custom board, PLC, robot controller, and laser control board operate as one coordinated system. The electrical documentation now matches the installed hardware.
It is a fair example of the kind of work I do on laser systems: measure what a system is actually doing, fix the control path, and leave documentation behind that outlives the visit.
Project Snapshot
- Robot
- Yaskawa MH12 / DX200 controller
- PLC
- Allen-Bradley CompactLogix
- Custom hardware
- Voltage-controlled oscillator PCB
- Software
- AutoCAD Electrical, MotoSim, Studio 5000