Laser steering and closed-loop temperature control

Laser steering and closed-loop temperature control

A start-up developing a new process for curing powder coats with a laser heat source was unable to close the temperature control loop in a stable way with satisfactory performance. The system uses a thermal detector co-boresighted with a high power industrial laser to heat powder coats to the curing temperature.

After failing with off-the-shelf industrial PID control solutions and experiencing frustration with motion control consultants, the company contacted IJK Controls to provide the controller at the heart of their technology.

IJK Controls rapidly developed and delivered a custom controller capable of closing the temperature loop at the extremely high bandwidths required. Most process control consultants are familiar with long time-scale systems, not the millisecond and microsecond times required for this novel process.

Once the basic technology was proven, IJK Controls built a first order model of the system dynamics and began to understand how other parameters (beam motion, material thickness) affected the loop. IJK Controls even built simple thermal finite-element models to further understand the process dynamics. This understanding allowed more informed and effective tuning of the process design variables such as spot size, feed speed, and detector optics and enabled more advanced control options.

In addition to providing the thermal controller, IJK Controls also supported the motion control and beam steering aspect of the program with custom developed software. The motion control solution also had to meet demanding performance and safety requirements.

By understanding and applying control theory and sound engineering, IJK Controls quickly developed the solution necessary for the customer to meet an important investor review. A plastics industry expert watching the investor demonstration commented that this was the first successful demonstration of the technology that he had seen after watching three previous laser-based powder coat systems fail.

IJK Controls goes beyond motion control consulting: we are able to put the hardware together with the theory.

Keywords: controls, motion control, temperature control, hardware design, firmware design, beam steering, process modeling, process design, parameter estimation, adaptive control, finite-element analysis, optics, optical kinematics