Error Modeling&Uncertainty Analysis Of The Large Gear In-Site Measuring System

The in-site measuring system with laser tracker for mega gear is aiming fordesigning a more capable measuring system which will have the advantage of thehuge volume measuring ability as a laser tracker and the precision as a CMM. In thisthesis, first we solved some essential problems in the implementation of themeasuring system and an error propagation module is developed, then the uncertaintyof the measuring system is achieved by the Monte Carlo Method (MCM).The in-site measuring system is a set of instruments of normal size that could beused to measure big gear, and it’s also a little bit more complicate to implement themeasurement than single instrument. An error propagation module is developed basedon the system designing conception and the detail of the measuring sequence. Notingthat it’s difficult to evaluate measuring uncertainty for coordinate measuring systemssuch as laser tracker and CMM, because there are many error sources, and thepropagation of these errors are sophisticated which makes the conventional evaluatemethods lack of availability and theoretical support. Uncertainty estimation of thein-site measuring system using the Monte Carlo method is implemented in this paper.First, it’s necessary to know the error sources well, such as their values anddistributions, with these variables and the propagation of the errors, a model of thewhole system can be formed. With this model we get mounts of samples of themeasuring points. At last, put the samples into an error evaluate software and we getmounts of evaluation results. Then it’s easy to evaluate the measuring uncertainty withthe A type method. The implementation of the MCM simulates the error distributionand propagation which happened in actual measuring process and avoid theintroduction of sensitivity coefficients. The MCM is successfully used in estimatingthe measurement uncertainty of involute profiles and produced stable results for thein-site measuring system. Now times most commercial coordinate measuring systemsare failed to provide task specific uncertainty reports, and the MCM is a superiormethod to solve the problems when a measuring system includes more than oneinstruments and the measuring process is sophisticated.