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The robot

 The robot on November the 20th 1999
Nearly 2 months have been spent since the rules were published. Many emails were sent by the Fribottes and tests in small groups have been carried on.

Result : we have made some significant progress, but there is a lot to do ! :-)

  The carrousel
How fit the MIOs in the carrousel, making easier their exit, and without turning the mechanics of the carrousel to difficult ?

The prototypes we tested made us choose to put 6 MIOs in the carrousel (and not 8 as we initially thought) for dimension reasons. Indeed, with a PIC board (or a 68HC11), the servomotors, the wheels, the sensors, the batteries, 8 MIOs will make them too small and difficult to build.

Instead of turning the carrousel to make the MIOs leave, a more simple way to put the MIOs into the carrousel is decided :

Disposition du manège

MIOs in the carrousel (view from above)


The previous diagram shows the MIOs inside the carrousel on the starting area.
The movement of the MIOs at the start is shown by the arrows.
The MIOs are drawn with their maximal size (a cube of 15cm side).

We can see on the diagram that there is enough room in the carrousel to put its locomotion system.
  The MIOs
  • The motorization

The choice of servo-motors has been validated (see the documents on servo-motors in the Technical DB).

  • The wheels

The wheels were found on 50 Francs toys (see the characteristics in the technical DB in the page related to the MIOs mechanics).
These wheels are very adhesive, they are small enough to fit in the MIO and big enough to provided an adequate speed.
The assembling of the wheels on the servo-motors is in the Technical DB.

Petite voiture
Toy from which the wheel have been taken

  • The batteries

For our MIOs, we choose cheap batteries. These are Ni-Ca accumulators of 600 mA found in supermarkets. We make a few loaded tests and we talk about it soon in the technical DB.

  • The frame

The frame is built with aluminium bars, servo-motors and 2 wheels, and in the front a small ball. A description of the realization of the frame is in the technical DB. To test the frame in movement, a test board with a PIC is put on it.


Prototype
Frame prototype

The final frame will have a prop under the ball to increase the ground clearance to 2cm. Our calculation for these MIOs give us a ground clearance of 1cm at least to be able to cross the hill. 2cm will then be OK.

Prototype
Climbing the hill

Regarding the tests we made on this MIO, the best manoeuvrability and the best adherence is obtained with a propulsion from the back of the MIO.

And it climbs the hill of more than 60%!!!
  The hot spot

Tests with transistors were not convincing, we made a new test with a resistive wire. Result : "BOOM"! hum.... the resistance didn't survive neither !


Fil résistif
Proof that it works !

  The sensors

The tests on the sensors are in progress : line sensors with photo resistances and a nearness sensor or beacon with infrared transmitter. When these tests will be finished, we will have a clear vision to make the PIC boards.

Oscillo
Tests with the oscilloscope lent by a benefactor ! :-))

We would like to thank Bernard who lent us his oscilloscope to help us make our robot! This loan is priceless !!! Because adjusting without an oscillo is quite difficult.... ;)



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Last modified : January 30th 2000