A Variable Configuration Force Sensor With Adjustable Resolution for Robotic Applications

Multitask measurements with different measuring ranges and resolutions have put forward higher requirements for force sensors. This article presents a novel variable configuration approach to develop an adjustable-resolution force sensor with a compact force-sensitive structure. Unlike the traditional strain gauge-based force measurement, the external force is detected through measuring the displacement of the deformed structure with a precision optical linear encoder. This approach can enable variable measuring range and force resolution through the continuous adjustment of structural stiffness. Specifically, the stiffness adjustment is implemented by changing the second moment of area of the sensor structure through rotating its build-in flexure beam shafts. Analytical models are established to provide the theoretical basis for analysis and design of the sensor. Furthermore, the validity of the design is evaluated with finite element simulations. Finally, a sensor prototype is developed for performance evaluation, and applied for the wire bond pull tests to evaluate the bond strength on the printed circuit board assembly. Experimental results show that it is effective to change the measuring range and force resolution of the developed force sensor through the stiffness adjustment.