Robotrex Robotic Dinasaur
Date: Monday, December 06 @ 09:19:37 EST
Topic: Ayaklę Robotlar
Here is our robotic project; Robotrex. A robotic dinosaur. Its name comes from the words
"Robot" and "tyrosaurus-Rex". Inspired from our older projects "Bigfoot" and "the Goggles",
this project was built specially for our endtas.com fair stand in 2004 Izmir international
fair. Instead of forgetting it around somewhere under dust i worked on a plywood cutting plan and
a computer model of it to share the project with our visitors.
The Robotrex uses the walking principle of the "Bigfoot". But along with the placing of servos to
its foot shape and the center of gravity, it has got some important structural improvements which are
the results of a careful study which took several days of time before the fair.Just like the Bigfoot,
this robot is also powered by two servos. But with one big difference instead of the servo placing
scheme of the Bigfoot where the servos were looking towards the outside of the body,
(with links also outside) this robot has them all inside the body.
The power transferring parts are also placed between the legs, inside the body almost completely hidden.
The feet-up-down servo is placed at the back, facing the inside of the robot-body where it used to
sit in the front of Bigfoot facing forward. The feet-forward-reward servo is placed at the front
bottom, facing backwards into the robot-body where it used to sit at the rear part of The Bigfoot facing
down. Where the power of the feet-forward-reward servo is transferred to the legs by means of a iron
wire, in Robotrex, a rigid plywood piece is used for the same purpose. And this concludes to a robot
which moves more determinently with better balance. The power of the feet-up-down servo is transferred
not to the tip of the feet like it is in the Bigfoot but to the mid part of the feet resulting a much more
stable standing robot. By means of the improvements like this and a much better center of gravity, the
power of the servos are transferred to the legs and ground with more efficiency resulting less
power loss due to structure. This also yields a longer battery life. The robotrex can run for hours
with its 4 rechargeable AA batteries.
As for the circuitry, nothing is different than the one used in our project "The goggles".
The sensors of the system:
a- Two sound sensors. Independent two condenser microphone sensors at the right and left. With these
sensors, the robot can hear the sounds around it and also differentiate between sounds coming from
the left side and right side.
b- Light sensor. This is a photodiode located at the front of the Robotrex facing forward. With this
sensor, the robot can sense and measure the light level around it as a 5 bit (0-31) value.
c- Infra Red (IR) obstacle detection. With this microprocessor based (OZZ-IR-DIS chip) dedicated circuitry
Robotrex can sense the obstacles on its way as well as obstacles at the right and left sides within a
limit of almost 40cms.
Along with the sensors, the Robotrex has got a "Mood" display consisting of a 5x7 dot matrix LED display
where it can display its mood as smiling, crying, scary etc faces (16 total). The mood display can also
be built and used as a stand-alone module. While the mood display is showing the emotions of the robot
the main processor can also produce a variety of sound effects to improve the communication of the robot
with the outer world.
The Robotrex which is powered by three separate microcontrollers, can also be built by using only one
micro, the main controller. In this scheme there wil be no mood display and no IR obstacle detection.
Moods can be expressed by sounds only and obstacles can be detected by the whisker type touch sensors
like we use in our robugs and in Bigfoot.
As the structure, you can use plywood for making the parts as well as mock-up plastics, sheet
aluminium etc. You can give organic forms over the finished structure by using polyurethane foam and
obtain a smooth surface by sanding and finalizing the shape by applying steel putty & resanding.
With these, the robot can become a better looking dinasaur or any creature you like. It is all up to you.
The project can be modified in any way you like. And finally, don't forget to send photos of your final
work to us so as to enable us make a special page about your Robotrexs'.
Before starting to build robotrex, don't forget to read more about its ancestors; The Bigfoot and
The Goggles. The circuit schematics, photos etc in those articles can be helpfull while building the
Robotrex. And if you have questions, just add them to the end of this article as comments. I'll try
to repply them as soon as possible. Have fun and build many dinosaurs. :)
Robotrex Plywood Cutting Plan
The goggles' source code and circuit schematic
Bigfoot's circuit schematic