FourByThree - D3.2 Motion planning and control of robots in collaboration with humans

This report describes all the activities developed in the FourByThree project in relation to the techniques developed in order to allow safe and friendly human-robot collaborative tasks. Specifically, the deliverable describes two main activities and their results: human aware motion planning and adjustment of the overall stiffness of the robotic arm based on human actions and intentions. oRecently, human-robot cooperation (HRC) research activities have focused on the development of new methodologies for the generation of safe robot trajectories. However, the applicability of such methodologies in a real context is limited due to the inherent uncertainty of robot trajectory execution time (i.e. the robot can avoid the worker by modifying its velocity along the path). In this context, an approach to estimate a confidence interval on robot trajectory execution time was developed. First, human arm movements are studied for a given set of assembly collaborative tasks: worker occupancy volumes and occupancy volume probabilities are derived. Then, a finite number of alternative robot trajectories, crossing human occupancy volumes with different occupancy probabilities, are generated. It is therefore possible to estimate a probability for the robot to reduce its velocity, and a confidence interval on the robot execution time. oThe ever-growing presence of robots in various aspects of our lives, especially in industry, has intensified the investigation of safe physical human-robot interaction (pHRI). In this research we present a novel active approach to address this topic. Assuming availability of sensory information (namely, the relative position and relative speed between human and robot), we employ a fuzzy inference mechanism to generate a decision for adjusting the overall stiffness of the robotic arm in the task-space direction(s) along the trajectory that is assumed to lead to a collision between the human and the robot, while not affecting the stiffness in other direction(s). The activities here after presented have bene published in: oPellegrinelli, S., Moro, F. L., Pedrocchi, N., Molinari Tosatti, L., & Tolio, T. (2016). A probabilistic approach to workspace sharing for human-robot cooperation in assembly tasks. CIRP Annals - Manufacturing Technology, 65(1), 57-60. http://doi.org/10.1016/j.cirp.2016.04.035 o(submitted-under review) Ali Shiva, Ahmad Ataka, Ali Shafti, Helge Arne Wurdemann, Kaspar Althoefer, "A Novel Fuzzy-based Approach to Real-Time Stiffness Adjustment in Robotic Manipulators for Safe Human-Robot Interaction", IEEE International Conference On Robotics and Automation, 2017