Creating the torso for YT4 added height, stability, and
body-like features. Working from the upper deck panel on
the base, I drilled eight 2-56 holes at pre-marked spots
mounting two 1/4” aluminum spacers to anchor down the
torso. Next, hubs were attached to the spacers along with
six inch aluminum tubing which created a ladder design,
making it taller yet stable, as well.
Repeating that step one more time going higher, the
top was bracketed together using a single custom-cut piece
of tubing to add some extra height. At the top of the
tallest tube, a hub was used to connect the tube to the
upper body of YT4.
The head and arms were added to the construction of
YT4 to give it a more authentic human-like appearance.
Using brackets from a servo erector set and 12 Hitec
645MG servos with 133 oz torque, the arms began to
replicate the characteristics of modern human beings.
All the servos were set up with a Propeller servo
controller driven by a BASIC Stamp 2 microcontroller. The
servo positions are set to limit different ranges, mimicking
the typical human range of motion. A seven inch LCD
monitor with built-in speakers sits on top of YT4’s
shoulders, along with a Logitech web cam mounted to
aluminum brackets which rests on a high torque servo.
The servo allows rotation of the head from side to
side to view all surroundings. The LCD screen is powered
by the main 12 volt battery source, while the web cam is
connected to a MAC Mini via USB. A video cable is wired
from the screen and connected to a DVI-to-RCA adapter
attached to the MAC. Sound cables are then run from the
head down to the speaker jack on the MAC Mini, thus
providing audio and video (refer to Figure 2).
In an attempt to replicate human senses, onboard
notification of the environment was created
by using the power of a Mac Mini G4 and five
BS2 and BS2PX single-board computers from
Parallax that run a PBASIC language
interpreter, bringing YT4 to life. Each
microcontroller has its own custom program
and task including remote motor control,
temperature measurement, tilt balance, and
object detection as seen in Figure 3.
One of the microcontrollers (using an
infrared temperature sensor with a 90 degree
field of view) is used for measuring
environmental temperatures. Developing a
code in PBASIC allows the sensor to measure
the temperature repeatedly. Once it
approaches either the hot or cold threshold
that is set, an alarm sounds and displays hot
or cold color assortments on the front chest
of the robot. Measuring temperature allows
the user to become aware of extreme
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