AN OPTIMIZATION STRATEGY FOR MAXIMIZING COORDINATE MEASURING MACHINE PRODUCTIVITY .2. PROBLEM FORMULATION, SOLUTION, AND EXPERIMENTAL RESULTS

In this, the second of two papers focused on optimizing CMM productivi ty, a strategy is presented for obtaining operating speeds that maximi ze CMM throughput. The strategy involves posing the objective and cons traints in terms of a nonlinear programming problem. The objective is to minimize measuring time, and constraints are on measurement quality , available motor power and other machine specific characteristics. So lutions to various measurement scenarios are given, computed with a ge neralized conjugate gradient method that uses a golden section accepta ble search method. Also, a sensitivity study is presented that utilize s the optimization strategy to determine how change to a CMM's design will affect overall productivity. In the final section, experimental r esults utilizing the optimally computed trajectories for both single a xis and multiple axis motion are given. In addition, an example is pre sented to demonstrate the implementation of the optimization strategy in an actual measuring application. In the example, a connecting-rod i s measured at three speeds: the machine's default speed, a speed const rained by available motor power, and the optimized speed (constrained additionally by measurement quality). The experiment demonstrates a 27 percent reduction in time for the optimized speed compared to the def ault speed using the Bartlett test for comparing variances in the dime nsional data obtained.