Development, Calibration and Testing of Three Axis Force Sensor

Strain Gauge based force transducers are widely used in instrumentation and primary sensing elements in Force and torque measurements. At present, force transducers are necessarily force and moment transducer. The analysis of three force and three moments is the basis for evaluation of forces in three directions. These transducers are typically popular as six-axis force / moment transducer. Due to evaluation of three forces and three moments, the mathematical analysis becomes complex. These six variables warrant intricate models (shapes) of transducer to facilitate compliant surfaces to sense force / moments in specific direction. The moment estimations may not be required in typical robotic assembly platforms where theses sensors are performing a role as feedback devices. The proposed transducer ignores moments (even though they exists) and considers only force components. The sensors ( strain gauge) pasted to three mutually perpendicular compliant surfaces. The transducer is randomly loaded, giving force components in three directions. One of the components will have effect on other two due to cross sensitivity. Thus load sensed in any mutually perpendicular direction is algebraic sum of force in that direction and a cross component of remaining two axis forces as result of cross sensitivity. A simple mathematical model is developed to arrive at actual forces in three directions to factor the effect of cross sensitivity. A tailor-made data acquisition card and an algorithm is developed to sense real-time forces. These transducers have wide range of applications.