a 16 MHz ATmega128 controller. This controller is an eight-bit
low power AVR processor with 128 Kbytes of Flash program
memory, 4 Kbytes of EEPROM (electrically erasable programmable
read-only memory), and 4 Kbytes of internal SRAM (static
RAM). The ATmega128 also includes three eight-channel,
10-bit ADCs (Analog-to-Digital converters) and several bus
interfaces including two USARTs (universal synchronous
asynchronous receiver transmitter), some SPIs (serial peripheral
interfaces), and I2C buses (inter-integrated circuit buses).
The controller in the cube that houses the battery and
motor functions as the master controller while the other
controller functions as the slave. The controllers connect to
each other via power lines and bi-directional 400 Kb/S I2C
buses. These connections may be established by a slip-ring
to ensure the unlimited degrees of rolling, according to
Professor Wei-Min Shen, Director, Polymorphic Robotics Lab,
Information Sciences Institute, University of Southern
California. I2C was selected because it provides just enough
bandwidth for this application while maintaining minimal
wiring. Both controllers oversee the technologies within
their own cubes including the sensors, communications,
power needs, and docking action, as well as the motors on
the master controlled cubes.
The master controller uses a wireless receiver for
remote motor control, motor disable, stopping modules,
and receiving serial commands. The ATmega128 measures
the voltage and output current of the battery. PWM pulses
— which are interfaced to the motors through an H-bridge
— control the motor speed.
A potentiometer measures the angle of the end
effector (cube) of each module. The ATmega128 uses an
SPI bus to communicate with each docking face. The
docking faces communicate with the modules attached
to them via 230K baud RS-232 lines. The SPI bus also
communicates between the microcontroller and a 3D
accelerometer/inclinometer. The docking face communications architecture uses four infrared receiver LEDs and a
transmitter LED to locate, recognize, and measure the
distance to other available modules for docking. Modules can
communicate with other modules up to one meter away.
The Hawaii Institute of Geophysics and Planetology,
University of Hawaii, together with Ames Research Center,
Lockheed Martin, and DigitalSpace worked with the
SuperBot platform to design three robotic systems for lunar
exploration. These include the SuperBot MULE (multi-use
lunar explorer), a SuperBot Mini-MIS (mini-mobile
investigation system), and a SuperBot HOMS (habitat
operations and maintenance system), according to
Strategies for Using SuperBots on the Lunar Surface — a
final report from the University of Hawaii.
The MULE would employ 120 of the SuperBot modules
(modules consist of two, connected, six-degree-of-freedom
cubes with gears, motors, and communications technologies)
Electronics between the SuperBot cubes.
which are able to cooperate to reconfigure themselves.
The MULE would attach these modules to a lunar rover
type chassis and tools tasked with autonomous geological
exploration of the moon’s surfaces and underground. The
MULE modules would separate and re-attach themselves
into different robotic forms each suited to differing explorative missions. Configurations include the addition of an
excavating arm for digging trenches and a seismic network.
Working with astronauts, the MULE would operate in
the excavating mode, drilling holes and trenches in the
ground and taking samples. The robot would function as a
SuperBots in the form of a walking robot.
SERVO 11.2009 11