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VISUAL
SOFTWARE TO
UNDERSTAND
ROBOT
FUNCTIONS
National Instruments, a leader in computer-based data
acquisition, was one of the sponsors and mentors of
FIRST
Robotics Team 418, from the Liberal Arts and Science
Academy of Austin (Texas) at
LBJ High School. With that
kind of expertise, it’s not surprising that Team 418 was one
of the best in the area of control innovations. Not only did
the team design a high-performing robot, but also it created
a measurement and display system to monitor robot
performance, and programmed a variety of autonomous
operations to provide versatility at the start of each match.
The control and display systems combined effectively to
help the team better understand the robot and its operating
characteristics.
“SEEING”
SOFTWARE
AS A CONTROL
ADVANTAGE
TEAM 418
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Camera Aiming for
Controlled Shooting
The robot skeleton began as a thin, alu-
minum angle frame that was riveted and
welded to form a strong machine foun-
dation. This material was selected for its
easy construction and flexibility in sup-
porting robot subcomponents. In addi-
tion, the lightweight structure helped
keep the robot’s center of gravity low.
Team
418s scoring system relied on
a dual set of rollers to trap balls and lift
them into a storage hopper. A conveyor
belt lifted the stored balls nearly 4 feet
(1.2 m), where they were ejected from
the robot by a powerful, dual-wheeled
shooting device.
The shooter was solidly housed in
an aluminum box frame with precision
bearings supporting each side of the
wheel’s drive shaft. A cowling, first pro-
totyped with wood and later fabricated
aluminum, served as a back-plate
against which the shooter wheels com-
pressed the balls. The complete shoot-
ing system was compact, rugged, and
protected to prevent damage from
opposing teams.
The frame, lightened to conserve weight,
supports all the motors, rollers, and sensors that
transport the balls from the playing surface to
the shooting system.
The robot frame is constructed with an alu-
minum angle, welded and riveted together. This
simple frame is the central structure of an inte-
grated ball-gathering and scoring system.
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Balls enter the bottom of the robot and
ride through the central frame to the shooting
wheel. Sensors detect the location of the balls,
and monitor robot functions to ensure the accu-
racy of each shot.
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Aiming was accomplished by rotating
the robot with the drive system. A pow-
erful, dual-speed, four-wheel drive sys-
tem was designed to quickly cover the
field and easily align the robot with the
goal. The drive and shooting systems
were used in tandem to position the
mechanisms and propel the balls into
the upper goal.
The camera provided in the
FIRST Kit
of Parts was an important sensor on
Team 418’s robot. The camera con-
stantly searched for the illuminated tar-
get on top of the goal. Once the light
was detected, the camera’s servo
motors kept the target centered in the
camera’s view. Data on the orientation
of the servo motors, when locked on
the target, was used to develop a tar-
geting solution for the robot. The cam-
era pan determined the alignment of the
robot, and the camera tilt established
the distance to the goal.
The distance the shooter could propel
a ball was a function of shooter speed—
a parameter that could be adjusted to
accommodate the robot’s distance from
the goal. The speed and resulting trajec-
tory were determined from testing. These
results were stored in the robot con-
troller’s computer memory, and could be
accessed to determine the required
speed based on the camera’s tilt angle.
These automated processes—to align
the robot and determine the shooting
speed—were just two of Team
418’s
many control innovations.
Computer models closely match the final
robot configuration. It is much easier to move
parts around in a computer model to examine
options and ensure fit, thereby eliminating prob-
lems during the construction phase.
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A stable shooing platform is needed to
reduce vibrations and deliver accurate shots into
the goal. Aluminum box tube is carefully fitted to
form the frame and support the shooting wheel.
Wood is a useful material to prototype
robot systems. The shooter system prototype
is constructed with wood to evaluate the
optimal spacing between the cowling and
the shooting wheel.
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