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Andy Stewart Senior Engineer andy@apl.washington.edu Phone 206-221-8015 |
Biosketch
Andrew Stewart's research supports the development of next-generation ocean science technology and the creation of new tools to improve robotic exploration of marine environments. Stewart's interests include dynamics and automated control of mechanical systems, decision-making dynamics in mixed teams of humans and robots, and development of deployable hardware for exploration of remote environments. Stewart contributes to all phases of development from conceptual design to prototype fabrication and testing. He has worked to develop a number of mobile sensor platforms, including unmanned air vehicles and autonomous underwater vehicles. Through employing control theoretic tools and design methodologies rooted in fundamental principles, Stewart aims to extend the limits of human presence in the ocean.
Education
B.S. Mechanical Engineering, University of California San Diego, 2006
M.A. Dynamics & Control Theory, Princeton University, 2008
Ph.D. Mechanical & Aerospace Engineering, Princeton University, 2011
Videos
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Propagating Undersea Vehicle Expertise APL-UW scientists and engineers mentor the UW ROV Team. The underwater robotics program at the University of Washington provides a dynamic learning environment for oceanography and engineering students to design, build, and operate an underwater remotely operated vehicle (ROV) from scratch. |
21 Mar 2013
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Publications |
2000-present and while at APL-UW |
Towards humanrobot teams: Model-based analysis of human decision making in two-alternative choice tasks with social feedback Stewart, A., M. Cao, A. Nedic, D. Tomlin, and N. Leonard, "Towards humanrobot teams: Model-based analysis of human decision making in two-alternative choice tasks with social feedback," Proc. IEEE, 100, 751-775, doi:10.1109/JPROC.2011.2173815, 2012. |
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1 Mar 2012 |
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With a principled methodology for systematic design of humanrobot decision-making teams as a motivating goal, we seek an analytic, model-based description of the influence of team and network design parameters on decision-making performance. Given that there are few reliably predictive models of human decision making, we consider the relatively well-understood two-alternative choice tasks from cognitive psychology, where individuals make sequential decisions with limited information, and we study a stochastic decision-making model, which has been successfully fitted to human behavioral and neural data for a range of such tasks. We use an extension of the model, fitted to experimental data from groups of humans performing the same task simultaneously and receiving feedback on the choices of others in the group. First, we show how the task and model can be regarded as a Markov process. Then, we derive analytically the steady-state probability distributions for decisions and performance as a function of model and design parameters such as the strength and path of the social feedback. Finally, we discuss application to humanrobot team and network design and next steps with a multirobot testbed. |
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The role of social feedback in steady-state performance of human decision making for two-alternative choice tasks Stewart, A., and N.E. Leonard, "The role of social feedback in steady-state performance of human decision making for two-alternative choice tasks," in Proc., 49th IEEE Conf. Decision and Control, 15-17 December, Atlanta, GA, 3796-3801, doi:10.1109/CDC.2010.5717531 (IEEE, 2010). |
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15 Dec 2010 |
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With an eye towards design of human-in-the-loop systems, we investigate human decision making in a social context for tasks that require the human to make repeated choices among finite alternatives. We consider a human decision maker who receives feedback on his/her own performance as well as on the choices of others performing the same task. We use a drift-diffusion, decision-making model that has been fitted to human neural and behavioral data in sequential, two-alternative, forced-choice tasks and recently extended to the social context with an empirically derived feedback term that depends on choices of other decision makers. |
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Steady-state distributions for human decisions in two-alternative choice tasks Stewart, A., M. Cao, and N.E. Leonard, "Steady-state distributions for human decisions in two-alternative choice tasks," in Proc., American Control Conference, 30 June - 2 July, Baltimore, MD, 2378-2383 (IEEE, 2010). |
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30 Jun 2010 |
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In human-in-the-loop systems, humans are often faced with making repeated choices among finite alternatives in response to observations of the evolving system performance. In order to design humans into such systems, it is important to develop a systematic description of human decision making in this context. We examine a commonly used, drift-diffusion, decision-making model that has been fit to human neural and behavioral data in sequential, two-alternative, forced-choice tasks. |
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Convergence in human decision-making dynamics Cao, M., A. Stewart, and N.E. Leonard, "Convergence in human decision-making dynamics," Syst. Control Lett., 59, 87-97, doi:10.1016/j.sysconle.2009.12.00, 2010. |
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1 Feb 2010 |
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A class of binary decision-making tasks called the two-alternative forced-choice task has been used extensively in psychology and behavioral economics experiments to investigate human decision making. The human subject makes a choice between two options at regular time intervals and receives a reward after each choice; for a variety of reward structures, these experiments show convergence of the aggregate behavior to rewards that are often suboptimal. |
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Integrating human and robot decision-making dynamics with feedback: Models and convergence analysis Cao, M., A. Stewart, and N.E. Leonard, "Integrating human and robot decision-making dynamics with feedback: Models and convergence analysis," in Proc., 47th Conf. Decision and Control, 9-11 December, Cancun, Mexico, 1127-1132, doi:10.1109/CDC.2008.4739103 (IEEE, 2008). |
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9 Dec 2008 |
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Leveraging research by psychologists on human decision-making, we present a human-robot decision-making problem associated with a complex task and study the corresponding joint decision-making dynamics. The collaborative task is designed so that the human makes decisions just as human subjects make decisions in the two-alternative, forced-choice task, a well-studied decision-making task in behavioral experiments. The human subject chooses between two options at regular time intervals and receives a reward after each choice; for a variety of reward structures, the behavioral experiments show convergence to suboptimal choices. |
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Inventions
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Methods for Underwater Haptic Rendering Using Non-contact Sensors Record of Invention Number: 46396 Wei-Chih Wang, Fredrik Ryden, Payman Arabshahi, Andy Stewart, Howard Chizeck |
Disclosure
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7 Feb 2013
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Virtual Fixtures for Subsea Technology Record of Invention Number: 46397 Andy Stewart, Fredrik Ryden, Howard Chizeck |
Disclosure
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7 Feb 2013
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