Dynamic Collaborative Workspace Based on Human Interference Estimation for Safe and Productive Human-Robot Collaboration
Mitsuhiro Kamezaki, Tomohiro Wada, Shigeki Sugano
Abstract
Collaborative robots that operate safely close to workers without fences have attracted attention, but few examples of such human-robot collaboration (HRC) have been seen in factories. The main reason is the difficulty in balancing safety and productivity. Current fenceless HRC systems stop the robot when a human enters the collaborative workspace ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CC</i> ) where both human and robot can work to ensure safety, which ISO/TS15066 regulates. The robot stops even when the human is far enough away, so productivity is drastically decreased (FCW, Fixed <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CC</i> ). If a system could identify the human-work area, designate it as a no-entry space in <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CC</i> for the robot ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CCPP</i> ), and dynamically set the closed <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CC</i> ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CCCC</i> ) with shrinking <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CC</i> by <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CCPP</i> , productivity would improve thanks to enabling the robot to work in <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CCCC</i> and safety would be ensured thanks to allowing the human to continue working in <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CCPP</i> . In this study, we propose a new concept of a dynamic collaborative workspace (DCW) that dynamically sets <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CCCC</i> and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CCPP</i> based on the human's predicted trajectory. It also provides visual and auditory prompts to enable the human to understand DCW states, i.e., when a human enters <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CC</i> , <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CC</i> is changed, and the robot is in emergency mode. We compared four HRC systems using a real robot arm: two conventional FCW ones with and without fences and two proposed DCW ones with and without a state indicator and found that the proposed system with a state indicator has the best productivity and ensures the same level of safety as the conventional system with fences.