Construction of an Avionics Box for a NonPrehensile Robot

1
Construction of an Avionics Box for a
Non-Prehensile Robot
Chris Swanson - Vermont Space Grant, Vytas
SunSpiral - Intelligent Robotics Group Ames
Research Center
Abstract
XP-08 Power Management
DC123S DC Converter
24V
24V
24V
24V
This summer I designed and built an avionics box
for a robot constructed by a senior design team
at the University of Idaho. The senior design
team, called the Lunartics, is part of Idahos
Robotic Lunar Exploration Program (RLEP) and is
being sponsored by NASA to build a robot capable
of non-prehensile soil manipulation. The robots
responsibilities, which include plowing, digging
trenches, and taking soil samples, are of
interest to NASA for future missions to the
moon. The Lunartics robot originally possessed
a simple avionics box that manipulated the motors
of the robots arm and a shovel for digging.
Plans to upgrade the motors power required
several new components, and after talking with
senior design lead John Lacy, I began designing a
new avionics box for the robot. I included many
new features such as a battery box which housed
eight Lithium-ion batteries to power the motors
and circuit boards, DC to DC converters to
increase and regulate the voltage, a CPU and
mini-screen to allow mobile troubleshooting of
the robot, and a remote kill switch to protect
against accidental damage to the robots arm.
Some of these parts I cannibalized from an
obsolete avionics box that two interns
constructed last summer to power a robotic arm in
the lab. Other parts required that I spec the
needs of the robot and order them individually.
I integrated these components with the components
the Lunartics already possessed in a new
plexiglass avionics box designed to fit on their
robots back. The larger avionics box provided
volume to spread components out for easy access
and the upgraded DC converters allowed more
powerful motors to be added to the robots arm.
These new components add power and versatility to
the robot, allowing additional applications that
were previously unattainable.
16V
16V
5V
To Encoder
24V
To Motor
DC1HV DC Converter
16V
12V
5V
Brushless
Controller
24V
To Brake
5V
16V
Kill Switch
To Encoder
5V
12V
12V
To Motor
Mini ITX Board
24V
5V
5V
To Brake
5V
To Encoder
12V
12V
The Lunartics Original Avionics Box
To Motor
Motor Minds
24V
8 Li-ion Batteries
Basic Stamps
Electrical Diagram for New Avionics Box

• Features to be added
• Larger plexiglass box
• Battery pack with Lithium-ion batteries for power
• CPU and MiniScreen for mobile troubleshooting
• DC Converters to power stronger motors
• Remote kill-switch for safety

Results and Conclusion
Background
The newly constructed avionics box (pictured
below) is capable of powering the three DC motors
that control the robots arm. The CPU can be
accessed anywhere because of the touchscreen.
The killswitch can be activated from over 50
meters away via a key fob and will instantly kill
power to the motors while leaving the electronics
running. The eight Lithium-ion batteries each
provide 95 watts of power to run the robot.
Ports mounted on the side of the box allow easy
connections for a serial cable, computer monitor,
keyboard, and mouse. The components are laid out
in an easily accessible manner to facilitate
further upgrades, fixes, or additions to the
electronics system. The end result is an
avionics box that is robust in design and suited
for control of an autonomous robot.
In the previous summer, two interns constructed
the avionics box pictured below to power an Amtec
arm and analyze the force-torque signals from a
robotic hand attached to it. Between then and
the beginning of this summer, their box became
obsolete and was replaced.
Design
I used an OceanServer power system consisting of
eight Lithium-ion batteries, an XP-08 power
consolidation board that drew 16V from the
batteries, and two DC-DC converters that
converted the 16V to 24V, 12V, and 5V. Two of
the robots motors are controlled by and receive
their power (24V for brakes, 12V for motors, and
5V for encoders) from identical Motor Mind
circuit boards that I took from the Lunartics
original avionics box. These Motor Minds receive
commands from two BASIC stamp controllers (one
taken from the original box and one newly
ordered) that interface with Labview. The other
motor is a brushless motor controlled by a
special controller we ordered. This controller
requires 24V to power the brushless motor (24V)
and its encoders (5V). The Mini ITX Board is a
Commell LV-675D Pentium M supplied by Logic and
supplies features such as a wireless card, hard
drive, fan power, battery management capability,
and USB connections for mouse and keyboard. The
MiniScreen attached to the ITX board is a 7 inch
touchscreen with an 800x600 pixel VGA monitor.
Pictured at the top of the next column is an
electrical diagram for the avionics box.
Obselete Avionics Box
In an effort to increase sustainability, I
constructed a separate box to house the
components necessary to analyze the hands
force-torque readings. The other components were
offered to a group of RAP students testing and
modifying the Lunartics robot. We decided to
use several of the new components in building a
new avionics box to replace the current one
(pictured top of next column.)
The Lunartics New Avionics Box (Mid-construction)
Acknowledgements
I would like to thank John Lacy, project lead
for the University of Idaho Lunartics senior
design group Vytas Sunspiral, my mentor and head
of the ArmLab Terry Fong, head of the Intelligent
Robotics Group and the Vermont Space Grant
Consortium