Development of a novel uniaxial force sensor with two-stage force resolutions

This paper presents the concept design of a novel uniaxial force sensor with two stage force resolutions. Unlike conventional stain-gauge-based force sensing devices, the developed force sensor measures an external force through measuring the displacement of a movable member suspended by a compliant mechanism. The compliant mechanism is specially designed to have two stiffness values within its workspace. The low stiffness is used for small range and fine resolution force measurement, while the high stiffness is used for large range and coarse resolution force measurement. In order to get the required performance, the static stiffness as well as the dynamics of the sensing system is analyzed both analytically and numerically. After a prototype sensor is fabricated, preliminary characterization tests are carried out to verify the accuracy of the theoretical model and validate the effectiveness of the proposed design. The experimental results indicate that the structure of the force sensor is compact, and it has the ability to measure both micro range and macro range forces within one setup, meanwhile keeps very fine resolutions.