May 1, 2015 20:48 WSPC - Proceedings Trim Size: 9in x 6in clawar15khan 1 An Innovative Torque Sensor Design for the lightest Hydraulic Quadruped Robot H. KHAN * , F. CANNELLA, D G. CALDWELL and C. SEMINI Department of Advanced Robotics, Istituto Italiano di Tecnologia Via Morego 30, 16163 Genova, Italy * E-mail: hamza.khan@iit.it http://www.iit.it/en/advanced-robotics.html High-performance legged robots that are required to navigate on unstructured and challenging terrain benefit from torque-controlled joints. High-fidelity torque measurements are crucial for proper joint torque control. Commercially available torque sensors are expensive and often hard to integrate into com- pact and light-weight robot leg designs. Custom-made sensors on the other hand often suffer from asymmetric behaviour with respect to direction of rota- tion or poor linearity, especially for small and compact applications. This work is motivated by the need to achieve reliable torque measurements for the newly developed, small-size hydraulically actuated quadruped robot MiniHyQ. The main contribution of this work is the development of a new innovative design of a strain gauge based torque sensor with a high degree of linearity, symme- try, and scalability (both in dimension and measuring range). Furthermore, the glueing and wiring of the strain gauges are easy thanks to the geometry of the sensor that allows direct access to the mounting surfaces, even in compact dimensions. We show the design’s symmetric (clockwise and counterclockwise rotation) and linear behaviour through virtual prototyping and experimental tests. Furthermore, we show how a small-scale instance of the sensor design is successfully installed on the MiniHyQ robot. Keywords : Quadruped Robot Design; Torque Sensor; Strain Gauge based Sen- sor. 1. Introduction In order to advance research faster, legged robots must become more man- ageable. So that dynamic experiments can be performed faster and more easily. The simplest way to achieve this goal is by reducing the size and weight of the robot. Currently, it is still area of great interest for designers to build a portable highly dynamic and versatile quadruped robot to run fast in all terrains. One of the key points of a successful of this kind of