Towards the design of a decoupled, two-dimensional, vision-based μn force sensor for microrobotics

In this paper, we present three designs for a decoupled, two-dimensional, vision-based μN force sensor for microrobotic applications. There are currently no reliable, off-the-shelf, commercially-available force sensors to measure forces at this scale, that can be easily integrated into standard microrobotic test-beds. In our previous work, we presented a design consisting of a planar, elastic mechanism with known force-deflection characteristics. It was inspired by the designs of pre-existing MEMS suspension mechanisms. A CCD camera is used to track the deformation of the mechanism as it is used to manipulate objects in a micro/meso-scale robotic manipulation test-bed. By observing the displacements of select points in the mechanism, the manipulation forces can be estimated. Here, a building block approach for conceptual synthesis of compliant mechanisms methodology is used to design for decoupled displacements for the tracking points when the tip is subjected to forces in the XY-plane. By designing mechanisms with circular compliance and stiffness ellipses along with zero magnitude compliance and stiffness vectors, we are able to achieve our design requirements. Validation of this approach with macro-scale prototypes and recommendations for scaling the designs down for microrobotic applications are offered along with a sensitivity analysis of the final designs yielding insights for microfabricating such designs.