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\begin{document}

\begin{labcover}
\labtitle{A Brief History of USV Autonomy Platforms at MIT}
\vspace{0.1in}
\labdate{Spring 2022}
\vspace{0.1in}
\labauth{Michael Benjamin, mikerb@mit.edu}
\labauth{Department of Mechanical Engineering}
\labauth{MIT, Cambridge MA 02139}
\labline
\end{labcover}

\wikidoc{file=Help.HeronHistory}
\wikidoc{auth=mikerb@mit.edu}

%a. early days: all about the BF21  1999-2020/present
%b. Autonomous kayaks 2003-2011
%c. Kingfisher M100 2012-2015
%d. WAM-V  2014 - present
%e. Kingfisher M200 2015-2018
%f. Heron M300 2018-2021
%g. Heron M400 2022-present
%h. Philos


%====================================================================
\section*{Introduction}
%====================================================================

The MIT autonomy software has been in development on campus since
roughly 2000. This sofware has been developed in simulation and on
robotic platforms, both underwater and surface. Initially the target
platform was underwater, the Bluefin 21-inch unmanned underwater
vehicle (UUV) as part of the ONR GOATS program. Soon after, relatively
low-cost unmanned surface vehicle (USV) platforms were introduced as a
means of intermediate field testing prior to UUV deployments. Over
time the mission, sponsors and platforms have evolved. This document
provides a brief history.

%====================================================================
\section*{The Early Days (Early 2000s)}
%====================================================================


The GOATS (Generic Ocean Array Technology Sensors) was a project,
initiated in 1998 in collaboration between MIT and NURC, with the
long-term objective of developing net-centric, autonomous underwater
vehicle sensing concepts for littoral MCM and ASW. This project was
funded by ONR Code 32. The core of the program was the exploitation of
collaborative and environmentally adaptive, bi- and multi-static,
passive and active sonar configurations for concurrent detection,
classification and localization of subsea and bottom
objects. Prof. Henrik Schmidt was the Principal Invesigator, with
Prof. John Leonard as the Co-investigator.

\vspace{0.2in}
\begin{figure}[H]
  \centering 
  \includegraphics[width=0.9\textwidth]{figures/goats_2002.png}
  \caption{The MIT Bluefin 21 inch UUVs at the GOATS 2002 exercise in
    Italy 2002, with the NATO Underseah Reseach Centre (NURC), now
    known as the NATO Centre for Maritime Research and Exploration
    (CMRE).}
\end{figure}
\vspace{0.2in}

During this era, UUVs typically ran missions that were largely
scripted.  Sensor data was primarily recorded for post-mission
processing and analysis. Furthermore, in this era the 21-inch UUVs and
the daily cost of ships to deploy them, were extremely expensive. Even
though UUVs contained fail-safes such as drop-weights and acoustic
locators, the conservative nature of scripted missions was a welcome
feature that ensured that a UUV would run a predictable course and
surface at a predictable location.

\vspace{0.1in}
\noindent
Even during this era, it was becoming obvious that UUVs were capable
of processing their on-board sensor data during the mission, and using
that data to make unscripted maneuver decisions. While {\em adaptive
  autonomy} may have only limited advantages in searching for mines,
it has enormous advantages in searching marine mammals or other
non-stationary underwater objects or ocean phenomena of interest.

\vspace{0.1in}
\noindent
The drawback of adaptive autonomy is that it introduces risk of
vehicle loss. In developing autonomy that adapts to sensed events,
care must be taken to consider the variations of sensed events to
ensure the autonomy system does not produce unexpected maneuver
decisions, resulting in vehicle loss. Proper simulation plays an
important role in ensuring the autonomy, but there is a saying
(commonly attributed to Rodney Brooks) "In simulation, you are doomed
to succeed".

\vspace{0.1in}
\noindent
To expand our UUV autonomy development to be based on a truly adaptive
and multi-vehicle collaborative structure, we needed to improve our
simulation to include simulated sensor, a simulated ocean environment,
and a multi-vehicle simulation capability. But equally important, we
needed to find access to a low-cost marine robotic platform that could
serve as a proxy for UUV missions prior to actual UUV deployments on
research vessels.


%====================================================================
\section*{The Autonomous Kayaks (Mid-late 2000s)}
%====================================================================

After GOATS 2002, Prof. John Leonard, brainstorming with Joseph
Curcio, an MIT Ocean Engineering alumnus from the nineties, conjured
the idea of a low-cost autonomous kayak, made mostly from commercial
off-the-shelf (COTS) components. Joe initially made four kayaks called
SCOUT (Surface Craft for Oceanographic and Undersea Testing) with
major contributions from Andrew Patrikalakis, a former member of John
Leonard's lab and MIT student (Curcio 2005). Soon afterward, in
roughly 2004, four more kayaks were constructed for the Navy for use
by Mike Benjamin, stationed at MIT as a visiting scientist. These
kayaks were purchased from Robotic Marine Systems, the company
recently launched by Joseph Curcio primarily to sell the SCOUT
platform to non-MIT groups.

\vspace{0.2in}
\begin{figure}[H]
  \centering 
  \includegraphics[width=0.9\textwidth]{figures/kayaks_2005.png}
  \caption{The MIT autonomous kayak (SCOUT) platforms, shown on the
    left on the docks of the MIT Sailing Pavilion, and on the right
    on the back deck of the R/V Leonardo in an exercise in Italy. The
    latter photo by Alex Bahr, a former PhD student of John Leonard,
    and co-founder of present-day Hydromea.}
\end{figure}
\vspace{0.2in}

\vspace{0.1in}
\noindent
During late 2003 and into 2004, the MOOS software (Newman) and IvP
software packages were merged into MOOS-IvP and field tested on the
autonomous kayaks on the Charles River. During this period the first
COLREGS collision avoidance algorithms were developed and tested,
(Benjamin 2004). In 2005, the MIT SCOUT platforms were further
field-tested during the Focused Acoustic Field 2005 (FAF'05)
experiments in Pianosa Italy. FAF'05 was also funded by ONR Code
32. During the first part of this exercise, Paul Newman and Mike
Benjamin conducted MOOS-IvP experiments on the autonomous kayaks in
the waters off Pianosa.  Toward the end of this exercise, the code was
migrated from the kayaks onto the Bluefin UUV and deployed on the last
day of experiments.

\vspace{0.1in}
\noindent
From mid-2005 until summer of 2006, the kayaks at MIT were further
used for autonomy development in preparation for a major UUV exercise
in Monterey Bay in August of 2006 (MB'06). The MIT Bluefin UUV ran for
the first time using what we now called the payload autonomy
arrangement with MOOS-IvP running on the backseat science computer and
Bluefin control and navigation software running on the front seat
computer. This was a major milestone in autonomy development for two
reasons. First was the use of the payload autonomy arrangement working
on a secondary computer in concert on a commercial vehicle,
coordinated with the native manufacturer's software. This arrangement
was the brain child of Dr. David Battle, a post-doc at the time at
MIT, and co-founder of present-day Mission Systems in Australia. The
second milestone of MB'06 was a subtle but important shift in the
structure of the autonomy mission itself. Prior to 2006, missions were
structured as a fixed sequence of events, culminating with a surfacing
and recovery after the last event. The MB'06 mission was structured as
a set of mission modes, where transition between modes depended on
sensed events, comms messages, and default transitions. This style has
persisted to the present day.

\vspace{0.1in}
\noindent
The introduction of the adaptive autonomy mission structure in MB'06
was not without contention. At the time it was perceived as risky. The
time and cost of the UUV and its towed sensor array at MB'06 were
substantial, and involved several research groups. Fortunately, the
chief scientist on the ship was Prof. Schmidt who had the final say.
The roughly two years of testing through simulation and on the
autonomous kayaks gave the science team the confidence to debut the
new autonomy structure on a high-profile exercise.

%====================================================================
\section*{The Clearpath Kingfisher M100s (Early 2010s)}
%====================================================================

Throughout the 2000's, the MOOS-IvP autonomy project was primarily
funded by ONR Code 31, and field-tested on a number of large ONR Code 32
projects such as GOATS and PLUSNet.  In 2011, Battelle began a
multi-year grant to MIT to leverage the MOOS-IvP project to create a
new MIT class in Marine Autonomy. A goal of this class was to provide
students with the ability to write autonomy software of their own and
field-test their work on marine vehicles on the MIT campus. At this
point the SCOUT autonomous kayaks were nearly a decade old. Robotic
Marine Systems (Joseph Curcio), the maker of the SCOUT platforms, was
deeply involved as the chief scientist of Juliet Marine, focused on a
completely different vessel. MIT needed another solution for providing
low-cost marine robots in time for the first class of MIT 2.680,
Marine Autonomy, Sensing and Communications, beginning in February of
2012.


\vspace{0.2in}
\begin{figure}[H]
  \centering 
  \includegraphics[width=0.9\textwidth]{figures/kingfishers_m100.png}
  \caption{The Clearpath Robotics Kingfisher M100 USV used a custom
    trimaran hull and frame, with Pelican case electronics boxes on
    both the port and starboard sides. A pair of differencial thrust
    trolling motors was mounted on each side. It contained a single
    computer with Clearpath software (and eventually MIT software),
    with a WiFi connection and RC control for launch and recovery. (On
    the left: Alon Yaari, PhD student Stephanie Petillo. On the right:
    PhD student Erin Fischell.)}
  \label{fig_kfish}
\end{figure}
\vspace{0.2in}

\vspace{0.1in}
\noindent
The Kingfisher USVs were the primary teaching and research platforms for
Marine Autonomy from 2012-2014. MIT eventually purchased four units. One
drawback to the M100s (and same for the kayaks) was that the thruster
propellers extended well below the waterline and were not movable. This
meant that, for each Kingfisher, the lab needed also to own a dedicated
cart for storing and moving the vehicle. The next version of the Kingfisher
solved this problem nicely.

%====================================================================
\section*{The Clearpath Kingfisher M200s (Mid 2010s)}
%====================================================================

The Kingfisher M200 was a complete re-design from the M100. It contained
dual collapsable pontoons, and used water jet propulsion instead of trolling
motors. The switch to water jet provided a couple advantages. First, it
allowed the vehicles to be safely placed directly on the dock, eliminating the
need to have a cart or stand for each vehicle. Lab space is precious and this
was a huge advantage. The second advantage was safety. Although the spinning
propellers were never really regarded as a danger, the major project in the lab
from about 2015 through 2019 was the Aquaticus project (www.aquaticus.org).
This project involved humans in motorized kayaks, co-deployed with the robots.
All experiments required human-subject approval, and the elimination of the
spinning props was helpful. The downside or the waterjet propulsion is that
reverse propulsion was only about 1/10th as effective which made the turning
speed slower than the M100s. Overall the M200 was a substantial improvement
over the M100.

\vspace{0.2in}
\begin{figure}[H]
  \centering 
  \includegraphics[width=0.9\textwidth]{figures/kingfishers_m200.png}
  \caption{The Clearpath Robotics Kingfisher M200 USV used custom-made
    pontoons and hull frame. From front to back it contained three
    sections. The main computer section, the battery section and the
    payload section. The payload section was empty, but had removable
    plates to access the water below. The MIT lab began using the
    payload section to hold a separate payload computer and power
    supply for the payload computer. The Clearpath computer provided
    an external connector to the payload section and the payload
    computer. Batteries were removable recharged externally. Our lab
    typically had two batteries per vehicle. (On the right: Arturo
    Parrales.)}
  \label{fig_kfish_m200}
\end{figure}
\vspace{0.2in}

\vspace{0.1in}
\noindent
The M200 came with one other important advantage. It contained a
separate payload section, and Clearpath supported a version of the
{\em payload autonomy} interface. This interface was implemented in
the style of NMEA text strings over a serial port. The Clearpath
interface was modeled after the Bluefin payload autonomy interface
developed for the MB'06 exercised discussed above. While the payload
computer was in a separate pressure sphere within the Bluefin UUV, the
payload computer on the Kingfisher was on a Raspberry Pi computer
inside a water-tight box. This computer box is known as a PABLO at MIT
and is in its fourth generation configuration. The first generations
were designed to work with the M200. The primary advantage of a
separate and removable payload autonomy computer was that different
users, e.g., student teams, could prepare their mission on their own
PABLO and insert the PABLO unit into any working M200. In the case of
the M100, students had to integrate their software onto a particular
M100 which creates scheduling conflicts when there are more users than
robots. Even with more robots than users, it meant that if one vehicle
were experiencing a mechanical problem, a user would need to
re-install their software onto another robot which can be
time-consuming. The swappable payload autonomy computer of the M200
was a very valuable feature indeed!

\vspace{0.1in}
\noindent
One drawback of the M200 design was that the computer section was
essentially inseperable from the vehicle body. MIT owned four M200s,
and as vehicles wear down, it was common to have a disabled vehicle
due to a computer problem, or due to a thruster problem. It was not
possible to swap components to create a working vehicle in a pinch.
The M300, coming next, solved this problem.

%====================================================================
\section*{The Clearpath Heron M300s (Late 2010s, Early 2020s)}
%====================================================================

In 2016, Clearpath began offering an improved version of the
Kingfisher, the M300. Due to a name clash with another vendor,
Clearpath also decided to change the name of the vehicle from
Kingfisher to Heron. In 2016 our lab was heavily invested in a DARPA
funded project called Aquaticus. A decision was made to upgrade the
four existing Kingfishers to the M300 configuration and purchase two
additional Herons. The Aquaticus project required fielding four Herons
simultaneously. Aquaticus event days involved substantial resources in
people and equipment, so our lab decided that a six vehicle inventory
was required.

\vspace{0.1in}
\noindent
Although the payload section remained largly unchanged in size in
location, everything in front changed. The computer section is
essentially a tray that bolts into the frame. The battery sits in the
tray completely obscuring the computer section underneath. The
removable computer section was a huge improvement over the M200
because it allowed a computer section to be swapped between vehicle
frames.

\vspace{0.2in}
\begin{figure}[H]
  \centering 
  \includegraphics[width=0.9\textwidth]{figures/herons_m300.png}
  \caption{The Clearpath Robotics Heron M300 USV, similar to the M200,
    used custom-made pontoons and hull frame. The M300 computer
    section is removable however, and can be seamlessly swapped
    between vehicle bodies. Clearpath supported an "MIT variant" which
    included and E-stop button. MIT also created its own payload cover
    with mounts for the GPS receiver and IMU.  (On the left, Simen
    Overeng, Oliver Os, Norwegian visiting students, Spring 2019.)}
  \label{fig_heron_m300}
\end{figure}
\vspace{0.2in}

\noindent
With the M300, MIT requested that Clearpath support a variant that
includes an E-Stop button. This was primarily advocated for by
Dr. Michael (Misha) Novitzky, an MIT post-doc managing the Aquaticus
project. The Herons were to be involved in human-robot experiments and
the E-Stop was sensible safety feature. In retrospect it is a good idea
for all vehicles regardless of experiment.

\vspace{0.1in}
\noindent
The payload section of the Herons also evolved quite a bit from
2016-2019.  In addition to Misha's additions and fixes to the Herons,
Dr. Paul Robinette, and Caileigh Fitzgerald also created both a
payload section tray, and payload cover shown in the above figure.
The Payload autonomy box (PABLO) was further modified in terms of the
connector layout, and separate payload computer battery box and
connnector was also improved. These modifications continue to be
essential features of the robots to the present day. While the E-Stop
is a modification supported by Clearpath, the payload autonomy box,
battery box, and mounting tray, and cover, are all MIT in-house mods
worked out by Misha, Paul and Caileigh.

\vspace{0.1in}
\noindent
A minor note: the ability to switch computer boxes between vehicle
frames is a major advantage, especially as vehicles age and begin to
wear down.  However, it does create a philosophical debate on whether
the name/identity of the vehicle is determined by the computer box, or
the vehicle body. While the body is bigger, the user interacts with
the computer. Over time it seems the computer has won this battle. We
tend to name our vehicles, and the name follows the computer box. 

%====================================================================
\section*{The Clearpath Heron M400s (Early 2020s)}
%====================================================================

The M400 contains a number of funtional improvements over the M300,
primarily focused on the computer box, the battery, and their
interface. Early M300 units occasionally had issues with water
integrity and corrosion around the battery terminals. While these
issues were largely resolved, a more robust fix was engineered by
Clearpath and offered in 2020. At the time of this writing MIT is
expecting six new computer boxes and six new batteries in the Spring
of 2022. 


%====================================================================
\section*{Present-Day Bluefin-21 UUV}
%====================================================================

In the 20+ year timeline discussed here, the Bluefin-21 UUV has
remained the crown jewel of our lab, participating in many ONR and
DARPA funded projects. It has also evolved its sensing, navigation,
and on board computing capabilities substantially. It has been fielded
with nose-mounted arrays, and multiple types of towed sensors. It most
recently was deployed at ICEX 2020 in the Arctic, and in ICEX 2016.
The under-ice missions are further notable in that hardware or software
faults that may normally result in an all-stop and surfacing, cannot
be tolerated under the ice. 

\vspace{0.2in}
\begin{figure}[H]
  \centering 
  \includegraphics[width=0.9\textwidth]{figures/bluefin_recent.png}
  \caption{The Bluefin 21-inch UUV have in recent years been primarily
    used for participation the Navy's ICEX experiments in the Arctic.}
  \label{fig_bluefin_recent}
\end{figure}
\vspace{0.2in}

\noindent
Each successive deployment over the last decade has attempted
increasingly complex missions in terms of autonomy, sensing,
communication and navigation. Nearly every member of our lab working
with the Bluefin UUV has take MIT 2.680 Autonomy, Sensing and
Communication, and experienced early in-water deployments with one of
the low-cost surface craft described above.



%====================================================================
\section*{References}

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