A miniature load cell suitable for mounting on the phalanges of human-sized robot fingers

Abstract

It is frequently accepted that tactile sensing must play a key role in robust manipulation and assembly. The potential exists to complement the gross shape information that vision or range sensors can provide with fine-scale information about the texture, stiffness, and shape of the object grasped. Nevertheless, no widely accepted tactile sensing technology currently exists for robot hands. Furthermore, while several proposals exist in the robotics literature regarding how to use tactile sensors to improve manipulation, there is little consensus. This paper describes the electro-mechanical design of the Robonaut 2 phalange load cell. This is a miniature load cell suitable for mounting on the phalanges of humanoid robot fingers. The important design characteristics of these load cells are the shape of the load cell spring element and the routing of small-gauge wires from the sensor onto a circuit board. The paper reports results from a stress analysis of the spring element and establishes the theoretical sensitivity of the device to loads in different directions. The paper also compares calibrated load cell data to ground truth load measurements for four different manufactured sensors. Finally, the paper analyzes the response of the load cells in the context of a flexible materials localization task.