1884. CG Measurement Error Analysis – New Technology Has Changed All the Rules

Paper

Abstract

This paper re-evaluates the basic methods for measuring center of gravity in light of the dramatic innovations in force measurement which have taken place in the last few years. The authors attempt to include all sources of error. These include the ability of the test operator to reliably determine the position of the unit under test relative to the reference datum of the instrument (”fixturing error”), effect of instrument lean, sensitivity (the smallest cg shift which can be detected), and linearity. The type of cg instruments analyzed are: the gas bearing rotary table moment measuring concept (using both load cells and the new active moment transducers), the multiple point weighing method (”three load cell method”), the moment of inertia method, mechanical rebalance methods, and spin balance cg determination. Typical errors for different test objects are determined, and recommendations are made for different applications. The authors conclude with an error summary of current available cg measuring instruments.