Preface
1 Laser triangulation ranging
The principle of the laser triangulation method is very simple. It uses a beam of laser to illuminate the target at a certain incident angle. The laser will produce diffuse reflection on the target surface. At another angle, the reflected laser is converged and imaged by a lens. The spot is imaged on the CCD ( Charge-coupled Device, photosensitive coupling component) on the position sensor. When the measured object moves along the laser direction, the light spot on the position sensor will move, and its displacement corresponds to the moving distance of the measured object. Therefore, the distance between the measured object and the baseline can be calculated by the algorithm design. value. Since the incident light and the reflected light form a triangle, the geometric triangle theorem is used to calculate the spot displacement, so this measurement method is called the laser triangulation method.
There are two types of laser triangulation ranging: direct and oblique. Generally, the common ones on the market are direct, and the oblique method is more complicated. The Halcon routine uses a direct approach.
2 Direct shot
Calibration
The calibration of the laser triangulation system camera is basically the same as the general 2D camera process. The construction of this system consists of an area scan camera and a laser transmitter. The steps are as follows:
- Use standard camera calibration procedures to determine the internal and external parameters of the camera;
- Determine the direction of the laser projection plane relative to the world coordinate system by calculating the pose of a plane facing z=0;
- From two consecutive profiles