Control

  Prototypical control system for control of path deviation. Copyright: © Jan-Niklas Schneider, 2023. CC BY-SA 4.0. Prototypical control system for control of path deviation.

In addition to modelable process behavior, stochastic behavior also occurs in Laser Material Processing (LMP). These deviations must be detected and compensated for against the background of processing components as accurately as possible. A significant advantage of the laser as a tool is that it is a mass-free tool, so that only the system for deflecting the laser beam has any mass. Theoretically, this allows very fast control of the process.

Problem

To leverage the potential of a massless tool - the laser beam - prototypical beam manipulation kinematics are used. These kinematics are similar to galvanometer scanners with one mirror, i.e. the beam is redirected by a mirror. This mirror can be rotated so that the beam path can be manipulated in one direction. Prototypes developed as part of the robotic systems enabler are used for facilitating low-complex design of control loops. However, migration to industry standard laser scanner systems is intenden. The three major control variables are:

  • Measured process variable: path deviation
  • Desired set point: zero,
  • Manipulated process variable: angle of mirror rotation.

The deviation of the attained trajectory from the command trajectory is the measured process variable. It is measured by camera, thereby making use of the sensors investigated in the sensors enabler. The desired set-point is zero, i.e. zero path deviation is the intended state. The manipulated variable is the angle of mirror rotation. The closed control loop incorporates a PID motor control which directly correlates with the angle of mirror rotation.

Research focus


Initial experiments have been conducted, proving that control of the deviations known to arise in robot-based LMP (frequency: 5 - 20 Hz, amplitude: +- 2mm) is possible (compare Figure 1). We are therefore currently looking to expand research on control.

Please contact PhD Christian Hinke or Thomas Kaster if you are interested in joining the group Digital Photonic Production.
Research aspects might be:

  • Design of control systems for LMP in close collaboration with other group members for support with kinematics and sensors
  • Simulation of the proposed system in close collaboration with other group members for support with kinematics and sensors
  • Simulation of the proposed system in close collaboration with other group members for support with modeling
  • Experimental validation of the proposed system in close collaboration with other group members