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Hobby Robotics Page |
| The
Hobby Robotics Page |
Here you'll find tips on turning an RC(remote control) toy car into a mobile robotic device.
I
purchased this car at Radio Shack a couple of years ago, and
playing with it by remote control has gotten kind of boring for
me, so I have decided to turn it into an autonomus robotic toy.
By
the way, let me tell you why the fastest way to get started into
mobile robotics, is by using an RC toy car/truck/tank:
1) Even as brand new
they are cheap, cost even less if aquired at garage sales. The
one for this project was purchased as brand new, but I have
aquired other 2 for only a couple of dollars each at garage
sales.
2) All the mechanical
things such as motors, gears, tires and steering system come
already built in them, all you have to do is remove the car's
electronics board and install your own microcontroller board,
motor driver board or IC and sensors.
Because of some non robotic projects in the past, I own the the F100 microcontroller
board from tecel micro.
Except for the steering motor, the 2 drive motors on this RC car
are very powerfull motors that require a very high current to be
driven, there's no way the popular L293D IC or any other IC can
drive these motors, it'll instantIy burn, that's why I also just
aquired the D100 motor driver board
from tecel.
Do
all RC toys require a motor driver board such as the D100?
No... there's millions of rc toys that their motors can be easily
driven by motor driver ICs such as the L293D, as a matter of fact
the motors in the two RC cars that I aquired at garage sales can
be driven by the L293D.
About the Car
Picture of the RC car after it's own electronics were removed |
The hanging wires coming out of it, are from the 2 drive motors and the steering motor. The white cylinders are D-size rechargable batteries. Note: This car was designed to be operated with a 6-battery C-size power pack, since I wanted to give it more battery power, a total of 9 D-size batteries were attached to the car's body with silicone glue, 6 of those can be seen on the picture, the other 3 are located in the bottom of the car.
Steering:
Before I opened the car, since it's equipped with digital
proportional steering, I always assumed that a standard servo would be taking
care of the steering, well... I was wrong.
In this car, the receiver and steering control electronics were
all in the same board. I found the servo position 5K pot to be
inside of the steering motor/gear box, that's why there are 5
wires coming out of the steering motor box, 2 for the motor and 3
for the 5K pot.
Let
me explain how I decided to control the steering without using
the car's electronic board:
Step
1)
I took apart a standard HS303 servo that I had no use for. Now...
let's recall that in a standard servo, both the position pot and
the motor are soldered to the servo's control board, so, after
taking note of the spots where the servo's 5K pot was soldered
at, I unsoldered it and removed it from the servo's control
board, I also unsoldered and removed the servo's motor from the
servo's control board.
Step
2)
Soldered the 3 wires from the car's pot in the spot where the
servo's pot used to be soldered at. Soldered the 2 wires from the
car's steering motor in the spot where the servo's motor used to
be soldered at... Now controlling the steering is just as easy as
sending control pulses to a standard servo motor.
There's a few more details to step 2 than I have time to write
for, but if you're in a similar situation and want more details,
send me an email.
| Finally got some spare time to take
one more picture. Here we see the car with 3 infrared sensors mounted in the front bumper, the D100 motor driver board and the F100 microcontroller board can also be seen, the servo controller board is so small I had to draw a yellow line pointing to it. The edge of the power supply board can barely be seen at the left. The F100 generates the signals for the D100 board, the steering servo board, and the infrared emiting LEDs. Latter on, I will add some more sensors such as sonar and for line following. To be continued.... |
|
More
pictures and programming tips comming...
In the mean time, here's a Tip:
Don't
ever spend any money on robotics books, the internet is
full of information on the subject. The book's writter might have
gotten most of the information from the web anyways.
Links
rc robots Check out this
page for tips on building and controlling your own mobile
platform from scratch.
if you have any suggestions or things that you'll be looking forward to, email me at: hobby_robotics@yahoo.com
