Modeling and Simulation of Dynamic Errors in a Coordinate Measuring Machine with 3-DOF Laser Interferometer

In this paper, by constructing a 3-DOF (Degrees of freedom) laser interferometer on each displacement axis of motion, the main errors during the coordinate measuring machines (CMM) motion are dynamically monitored. The 3-DOF laser interferometer is composed of three-beam dual-frequency laser interferometers, and each dual-frequency laser interferometer obtains the reflection signal through a corner cube reflector. By determining the position parameters of the three corner cube reflectors and three sets of feedback signals, the 3-DOF laser interferometer can calculate the three parameters, i.e., the axial displacement and the lateral pitch and yaw angles. The device is installed on each motion axis of the CMM to monitor 9 major errors during the whole motion system. Laser signals are used to track position information by establishing the rigid body transformation relationship. Therefore, the 9 errors can be updated in real time through the monitoring system to replace the calibration results to calculate the probe position. The position error of the CMM probe caused by the dynamic error is simulated. Monte Carlo method is employed to obtain the error situation and monitor the residual error distribution throughout the measurement movement process. The errors can be corrected immediately without recalibrating the CMM error parameters especially when the dynamic error changes significantly. In addition, environmental errors are also introduced in the model to analyze the impact on the accuracy of position monitoring. The method proposed can reduce the position monitoring error within 0.1 mu m. Using this method, the error source of a dynamic error monitoring system can be designed in a simulated environment, which can be used as the basis for the design of the dynamic error monitoring system.