conditions that might pose a potential problem for YT4
while in remote operation.
Another program carried out by one of the BS2s is
measuring tilt and tilt degree with the Memsic 2125 dual-axis accelerometer. Utilizing the tilt sensor allows the user
to travel different terrains and become aware of changes in
gravity that are undetectable with the web cam. When
YT4 is going up or down a steep incline or climbing over
an object, the tilt sensor will measure the x and y axis. If it
is beyond the set maximum angle degree, an alarm goes
off eliminating any chance of destruction.
A Ping))) sensor is also connected to a microcontroller
positioned behind the robot to detect people and/or
objects approaching from the rear for security purposes.
The Ping))) sends a pulse to pin 13 on the BS2 for 10
micro/sec, then receives and stores the data continuously.
Using IF THEN ELSE statements, < or = symbols, and
constants, it will be able to determine if something
interrupts its path by calculating new distance
measurements then comparing them to the old
distance measurements. Once movement is
detected within a 60 cm range, an alarm tone is
activated warning the operator someone or
something is behind YT4.
Being able to navigate the environment by sight is
critical and require utilization of a Logitech USB web cam
connected to the Mac. Operating YT4 remotely requires
real time vision to view surroundings and to communicate
with others. Using the live web cam feed or a video chat
application, live video can be viewed from the web cam
on YT4 to a remote laptop. Using a video chat application
within the remote desktop program, the user is able to
video chat using two different application accounts.
Video chatting between the Mac and a PC allows the
user to view themselves from the web cam on their laptop
while viewing video from the Mac web cam within the
same shared screen. Being able to view yourself (as shown
in Figure 5) allows the user to project their image to
YT4’s LCD screen while viewing Mini’s web cam in a
split screen. While the user’s image is projected to the
robot’s screen, people see their face in real time on
the robot as it is interacting, and at the same time the
user can have full vision of the environment during
operation of YT4.
The track system used has upgraded 12 VDC gear
head motors with a 50:1 reduction which produces
152 RPM. Driving the motors are two HB- 25 motor
controllers daisy-chained to a Stamp 2 microcontroller
as shown in Figure 6. Removing the jumper from the
second motor controller, installing a three-pin jumper
extension cable from one motor controller to the
other, then installing another three-pin cable extension
from the first motor controller to pin 15 on the
60 SERVO 08.2011