Vision-based Laser Tracking with Scanning laser Doppler vibrometer

DFG grant number: RE 3980/7-1

Motivation

Laser Doppler vibrometry enables precise and non-contact measurement of structural vibrations. However, measurements become more challenging when the target object is moving. In this case, the measurement laser has to follow the motion of the target in order to remain at approximately the same measurement location.

Without tracking, the laser beam remains fixed while the target moves underneath it. Consequently, different locations of the moving structure are measured over time. This can influence the measured vibration amplitudes and introduce additional features into the vibration spectrum, making the interpretation of the measurement more difficult.

Vision-based laser tracking enables a scanning laser Doppler vibrometer to follow moving measurement targets without requiring any external instrumentation on the moving target. However, reliable tracking requires continuous information about the target position. If the visual landmark is temporarily hidden, the tracking reference can be lost and the laser beam can move away from the intended measurement region.

Objectives

• Development of image-based laser tracking for vibration measurements on moving targets
• Improvement of tracking robustness during temporary loss of the visual target
• Investigation of the influence of laser tracking on the measured vibration response
• Extension toward multi-beam tracking for three-dimensional vibration measurements on moving targets

Methods

• Detection of a visual landmark and determination of the target position using image processing  
• Implementation of control techniques for steering the galvanometric scanning mirrors
• Investigation of predictive methods for maintaining target-position information during temporary visual interruptions
• Evaluation of tracking performance and its influence on vibration measurements

• A Talukder, C. Rembe:
  Vibrometry using a Scanning Laser Doppler Vibrometer and ArUco Marker
  ^{In: 23. ITG/GMA-Fachtagung Sensoren und Messsysteme 2026, D3-3.3, pp. 272-277 (2026). DOI:10.5162/sensoren2026/D3-3.3}
• A Talukder, C. Rembe
  Vision-based Kalman-PID-assisted laser tracking for laser-vibration measurements on moving targets, Results in Engineering
  ^{(under review)}