34 Optimal Design for High Precision Stiffness Surveying Instrument

New approaches were explored to overcome the difficulties existing in stiffness measurement. Based on the optimal design, a portable and high-precision surveying instrument with a recumbent T-shaped mechanical body was developed for measuring the stiffness of sheet metal. Accurate force transducer and grating sensor were used to measure the loading force and the deformation respectively. A three-foot organ was designed to determine the normal direction of the specimen, which ensures the rationality and accuracy of the stiffness measurement. The improved least square method was adopted in the special software to process data and to calculate the stiffness value of the specimen. This instrument with the accuracy of better than 0.1%FS can also be applied to evaluating characteristics related to deformation or/and loading force.