A variable acceleration calibration system combines an innovative mechanical system and a statistical design of experiments to calibrate multi-axis force transducers. This system can reduce calibration time, allow for improved calibration of large-scale transducers, provide mobility for on-site calibrations, allow multiple transducers to be calibrated simultaneously, and accommodate dynamic force calibration.

State-of-the-art calibration systems include manual dead-weight calibration stands, automated calibration machines, and the Single Vector System (SVS). All three of these machines rely on generating force under constant gravitational acceleration by changing the mass (force = mass × acceleration). The current innovation holds the mass constant and changes the acceleration, thereby generating large forces with relatively small masses. This also allows for multiple forces to be applied without changing the mass, and dynamic forces can be applied by oscillating the acceleration.

This design provides improved efficiency and new capabilities for force calibration. The most recent state-of-the-art calibration system used is the SVS. This system is unique because it is the only force transducer calibration system that uses a single applied force vector — gravity.

By pitching and rolling the transducer, and by changing the location of the applied gravitational force relative to the transducer moment center, combinations of all six force components can be achieved. This loading technique, in conjunction with a statistically rigorous loading sequence, makes the SVS more efficient and accurate. In addition, the SVS uses less complex hardware compared to the other calibration systems; hence, it is considered the mechanically simplest of the three systems.

This work was done by Peter Parker, Ray Rhew, and Thomas Johnson of Langley Research Center; and Drew Landman of Old Dominion University. LAR-18065-1