Design and Manufacturing of a Mechatronic Device for Torque Estimation in Online Robotic Applications

This paper presents design and fabrication of a mechatronic device for measuring of exerted actuating torque on robotic joints, and also power consumption. The main objective is designing a simple, low cost and reliable device that has capability of measuring the actuating torque and consumed power of each joint of the robotic manipulator in object manipulation tasks. These quantities are required for torque control algorithms implementation, and performance analyses. The designed sensor is used in online applications of robotic manipulators for grasping tasks such as single or cooperative manipulator with fixed base and mobile manipulators. First, a brief classification of robot sensors as Proprioceptive sensors and Exteroceptive sensors is discussed. Next, the motivation of designing such a device is explained. An experimental set-up for grasp planning procedure by an industrial robotic arm and the role of this device are explained. Evaluation process is based on the new proposed performance index, MAG. The formulation of MAG index that is evaluating the quality of grasp configuration is described. Then, torque computation based on current measurement is discussed, and the structure of device is presented. Finally, obtained testing results are presented that reveal the sensitivity and linearity of the device are in the desirable control limit, so this device could be used in predicted applications.