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Andy Stewart





Andrew Stewart's research supports the development of next-generation ocean science technology and the creation of new tools to advance capabilities and maintain strategic advantage for the U.S. Navy.

His interests include vehicles, marine renewable energy technologies, remote sensing, and robotics. Through employing design methodologies rooted in fundamental principles, Stewart contributes to all phases of project development from conceptual design to fabrication, testing, and deployment.

In addition to conducting federally-funded research, Dr. Stewart is actively commercializing technology developed within the Laboratory and frequently collaborates with industry to aid transition.

In 2014 Dr. Stewart joined the executive committee of the Pacific Marine Energy Center as Associate Director.

Department Affiliation

Ocean Engineering


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, 2012


Persistent Environmental Monitoring Near an Operational Wave Energy Converter

In the first demonstration of the technology, the WEC supplied all the power needed by the multi-sensor Adapatable Monitoring Package.

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15 Jul 2019

For over 6 months, ocean environment observations were captured by the sensor package powered only by the ocean waves at the U.S. Navy Wave Energy Test Site off Oahu, HI.

Here, offshore Hawaii, the Navy is interested to understand the risk of interactions between wave energy conversion devices and marine animals, especially humpback whales. During its deployment the acoustic, sonar, photo, and video sensors detected, characterized, and recorded marine animals (no whales) relying only on the wave power captured by and converted to electricity by the Fred. Olsen BOLT Lifesaver buoy.

Knotty Dawg: Student-Designed, Student-Powered Submarine

The 2017–2018 UW Human-Powered Submarine Team is ready for international competition. They hope to set speed records with their two-person vehicle constructed mostly of wood.

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25 May 2018

The UW's entry in the first International Submarine Races competition in 1989 was built at APL-UW and the team was comprised of Laboratory scientists and engineers, and UW students. Since then, the team has been an active club in the UW Department of Mechanical Engineering.

APL-UW Principal Engineer Andy Stewart serves as the team's faculty advisor, so many of the design and build activities have returned to APL-UW facilities. Taking inspiration from the 1989 sub that was constructed of spruce strips coated by a fiberglass shell, the UW team collaborated with the Northwest School of Wooden Boatbuilding on Knotty Dawg — a two-person sub with a hull made of red cedar strip planking and fiery khaya veneer.

Wave Energy Buoy that Self-deployes (WEBS)

The Wave Energy Buoy that Self-deploys (WEBS) converts surface wave energy to mechanical and electrical power. WEBS is an easily deployed power station that can operate anywhere in the off-shore environment. Potential applications include power sensor payloads for scientific instrumentation; power station for autonomous systems, undersea vehicles, and/or surface vessels; and communications relay.

Research collaborators are the Monterey Bay Aquarium Research Institute and Columbia Power Technologies.

13 Dec 2016

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2000-present and while at APL-UW

Adaptable Monitoring Package development and deployment: Lessons learned for integrated instrumentation at marine energy sites

Polagye, B., J. Joslin, P. Murphy, E. Cotter, M. Scott, P. Gibbs, C. Bassett, and A. Stewart, "Adaptable Monitoring Package development and deployment: Lessons learned for integrated instrumentation at marine energy sites," J. Mar. Sci. Eng., 8, 553, doi:10.3390/jmse8080553, 2020.

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24 Jul 2020

Integrated instrumentation packages are an attractive option for environmental and ecological monitoring at marine energy sites, as they can support a range of sensors in a form factor compact enough for the operational constraints posed by energetic waves and currents. Here we present details of the architecture and performance for one such system — the Adaptable Monitoring Package — which supports active acoustic, passive acoustic, and optical sensing to quantify the physical environment and animal presence at marine energy sites. we describe cabled and autonomous deployments and contrast the relatively limited system capabilities in an autonomous operating mode with more expansive capabilities, including real-time data processing, afforded by shore power or in situ power harvesting from waves. Across these deployments, we describe sensor performance, outcomes for biological target classification algorithms using data from multibeam sonars and optical cameras, and the effectiveness of measures to limit biofouling and corrosion. On the basis of these experiences, we discuss the demonstrated requirements for integrated instrumentation, possible operational concepts for monitoring the environmental and ecological effects of marine energy converters using such systems, and the engineering trade-offs inherent in their development. Overall, we find that integrated instrumentation can provide powerful capabilities for observing rare events, managing the volume of data collected, and mitigating potential bias to marine animal behavior. These capabilities may be as relevant to the broader oceanographic community as they are to the emerging marine energy sector.

Station-keeping simulation of a non-moored WEC

Rusch, C., B. Polagye, J. Joslin, and A. Stewart, "Station-keeping simulation of a non-moored WEC," Proc., 4th Marine Energy Technology Symposium, 25-27 April, Washington, D.C. (2016).

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25 Apr 2016

While most concepts for wave energy revolve around anchored or tethered wave energy converters (WECs), untethered WECs may have broader potential applications. The lack of an anchor simplifies deployment and recovery operations and eliminates a component of the WEC that constitutes approximately 10% of the capital expense.

We explore the dynamics of an unmoored WEC using numerical simulations of a free drifting WEC under various environmental forcing conditions. The feasibility of device station keeping is also assessed.

Extrinsic calibration of an RGB camera to a 3D imaging sonar

Marburg, A., and A. Stewart, "Extrinsic calibration of an RGB camera to a 3D imaging sonar," Proc., OCEANS 2015, 19-22 October, Washington, D.C. (MTS/IEEE, 2015).

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19 Oct 2015

The introduction of low-cost RGB-depth (RGB-D) sensors have led to a diversity of algorithms for robust 3D scene reconstruction under controlled settings, but the underwater realization of such algorithms has been hampered by the constrained performance of most RGB-D sensors in water. We explore the possibility of fusing a point cloud generated from a high-frequency, mechanically scanned 3D imaging sonar with visual data from a camera to create a rich 3D representation of objects in the water column. A state-of-the-art algorithm for depth sensor-to-camera registration utilizing concurrent images of spherical targets is adapted, and the resulting alignment is used to combine sonar and visual imagery.

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In The News

Repairing dead satellites with robots

ZDNet, Greg Nichols

There are more than 8,000 manmade objects orbiting earth, and a large portion of those no longer perform any function. Space debris is of increasing concern as barriers to launching satellites continue to fall, and the problem is only getting worse.

Rehabilitating and updating dead satellites could slow the space debris problem. The only catch is that working on satellites in space is prohibitively expensive.

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23 May 2019

But robots could help. A company called Olis Robotics has announced receipt of a grant from the U.S. Air Force to streamline the control systems of robots that could operate in space to make satellite rehab practical. The Small Business Innovation Research (SBIR) grant, which begins with an initial $50,000 and could lead to as much as $1.5M in future funding, will go to advancing Olis's AI-driven software platform.

Formerly known as BluHaptics, Olis has eschewed hardware to focus on a software platform that can expand the capabilities of pilot-controlled service robots in dynamic environments like space, deep oceans, and various field operations. The software is designed to improve robotic dexterity, precision, efficiency, and overall mission success, as well as to bring multiple piloted field robots under one streamlined control module…

Electric maritime company comes to Anacortes

GoSkagit (Skagit Valley Herald), Julia-Grace Sanders

A new Anacortes, WA, company hopes to design and manufacture components for electric maritime vessels in Skagit County. Andy Stewart comments on the environmental and economic benefits of research and commercial vessels.

27 Dec 2018

Underwater sensors for monitoring sea life (and where to find them)

UW News, Sarah McQuate

Harvesting power from the ocean, through spinning underwater turbines or bobbing wave-energy converters, is an emerging frontier in renewable energy.

Researchers have been monitoring how these systems will affect fish and other critters that swim by. But with most available technology, scientists can get only occasional glimpses of what’s going on below.

13 Dec 2018

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Integration of Auxiliary Sensors with Point Cloud-based Rendering and Virtual Fixtures

Patent Number: 10,394,327

Andy Stewart

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27 Aug 2019

Apparatus and methods for generating virtual environment displays based on a group of sensors are provided. A computing device can receive first data about an environment from a first group of one or more sensors. The computing device can model the environment as a virtual environment based on the first data. The computing device can determine whether to obtain additional data to model the environment. After determining to obtain additional data to model the environment, the computing device can: receive second data about the environment, and model the environment as the virtual environment based on at least the second data. The computing device can generate a display of the virtual environment.

Haptic Virtual Fixture Tools

Patent Number: 10,226,869

Howard Chizeck, Andy Stewart, Fredrik Ryden

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12 Mar 2019

Apparatus and methods for defining and utilizing virtual fixtures for haptic navigation within real-world environments, including underwater environments, are provided. A computing device can determine a real-world object within a real-world environment. The computing device can receive an indication of the real-world object. The computing device can determine a virtual fixture that corresponds to the real-world object based on the indication, where aspects of the virtual fixture are configured to align with aspects of the real-world object. The computing device can provide a virtual environment for manipulating the robotic tool to operate on the real-world object utilizing the virtual fixture. The virtual fixture is configured to provide haptic feedback based on a position of a virtual robotic tool in the virtual environment that corresponds to the robotic tool in the real-world environment.

Methods and Systems for Six-degree-of-freedom Haptic Interaction with Streaming Point Data

Patent Number: 9,753,542

Howard Chizeck, Fredrik Ryden, Andy Stewart

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5 Sep 2017

Methods, articles of manufacture, and devices related to generating six degree of freedom (DOF) haptic feedback are provided. A computing device can receive first depth data about an environment. The computing device can generate a first plurality of points from the first depth data. The computing device can determine a virtual tool, where the virtual tool is specified in terms of a translation component for the virtual tool and a rotation component for the virtual tool. The computing device can determine a first force vector between the virtual tool and the first plurality of points. The computing device can send a first indication of haptic feedback based on the first force vector.

More Inventions

Acoustics Air-Sea Interaction & Remote Sensing Center for Environmental & Information Systems Center for Industrial & Medical Ultrasound Electronic & Photonic Systems Ocean Engineering Ocean Physics Polar Science Center