This paper explored the approach to solve the problems, such as instability of loading force and difficulty in measurement of deformation. A portable and high precision stiffness surveying instrument was developed for measuring the stiffness of large sheet metal. Combined with the mechanism, high accurate force sensor and grating sensor were used to measure the loading-force and the displacement. A special software named Stiffness Test(ST) was developed to process data and calculate the value of stiffness. In the practical test...
