Hao Ding, Kurniawan Wijaya, Gunther Reißig, and Olaf Stursberg.
Online Computation of Safety-Relevant Regions for Human Robot Interaction.
Proc. 43rd Intl. Symp. Robotics (ISR), Taipei, Taiwan, August 29-31, 2012.
For scenarios of robotic manipulators interacting with humans in a shared workspace, it is of paramount importance to avoid collision and to guarantee safe interaction. Thus, safety-relevant regions, i.e., regions of the workspace which are possibly occupied by a human, need to be reliably predicted and excluded from the workspace in which robot trajectories are planned. In our previous work, we have proposed using the probabilistic framework of Hidden Markov Models (HMMs) to account for the non-determinism in human motion. Such models often lead to sufficiently accurate predictions of safety-relevant regions (as opposed to single, most likely human positions) if the human motion follows one of a finite set of known motion patterns. However, predictions may be inaccurate to the extent of being useless if an unknown motion pattern is encountered, which may degrade the robots performance and may also cause safety problems. In this paper, the latter problem is avoided by combining HMM-based prediction with reachability analysis. This analysis is based on the present observation of the human's position, on dynamic limits of human motion such as velocity and acceleration limits, and on bounds of measurement errors. Based on the proposed method, a prediction of the unsafe region of the workspace can be computed online. This way, one arrives at motion plans for the robot, which are safe in the sense that collision between human and robot is avoided with a probability not less than a predefined threshold. The practicability of our method is successfully demonstrated by online predicting the motion of human hands in two scenarios with different human workers, multiple motion patterns, and multiple goals. The method is embedded into a scheme for online optimization of trajectories for an industrial robot which interacts with a human worker.
BibTeX entry:
 author = {Hao Ding and Kurniawan Wijaya and Gunther Rei{\ss}ig and Olaf Stursberg},
 title = {Online Computation of Safety-Relevant Regions for Human Robot Interaction},
 booktitle = {Proc. 43rd Intl. Symp. Robotics (ISR), Taipei, Taiwan, } # aug # { 29-31, 2012},
 year = 2012,
 url = {http://www.reiszig.de/gunther/pubs/i12rHMM.html}

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