A 6-Axis Force-Torque Sensor to Achieve Compliant Behavior in an Omnidirectional Mobile Platform for Wheeled Humanoid Robots

This work presents the design of a multi-axis force-torque sensor based on strain gauges located on its planar surfaces (frontal and back sides) for easy installation, to measure external forces in a direct and simple way, due to physical interactions between the mobile platform of a humanoid robot and the environment (objects and humans). This is an outstanding feature, because the estimation of those interaction forces will allow the humanoid robot to execute manipulation tasks using an unusual body part (mobile platform) and to distinguish between intentional and unintentional contacts known as gesture recognition, and at the same time, guarantying a safe interaction between a wheeled humanoid robot and the environment. All the aforementioned is achieved while the mobile platform is carrying a heavy load (the upper body of the humanoid robot). The force-torque sensor was designed using a finite element analysis (FEA), and the results show that it is possible to distinguish each component of the wrench <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\bar{F}$</tex> with a low coupling, having a good isotropy and a high sensitivity, due a suitable and strategic composition of the Wheatstone bridge circuits.