Abstract: In order to implement 3D measurement utilizing structured-light sensors, the matrix for transforming the 2D data from the sensor into 3D data is firstly established. By measuring a ball using the sensor, the distance between two circles on the ball and the distance between two positions of the CMM scanning axis is found possessing linear relationship. This enables the sensor to measure a fixed point (ball center), thus some “conjugate pairs” for solving the matrix are identified. Finally, a method for searching optimal solution of the three rotational angles is proposed. With the increment of the three rotational angles in a range, the 2D data picked up on the ball is transformed into 3D data using each set of angles, at the meantime a sphere is fitted using the 3D data. The summation of distance between the 3D data and the fitted sphere surface is calculated, the angles corresponding to the smallest summation are the optimal solution. The procedure of calibration is simple and facilitative for practical application, the solution is proved to be accurate by experiment.

Key words: Calibration, Conjugate pair, Extrinsic parameter, Searching optimal solution, Structured light sensor