Instructional Material: How to build the robot

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I recommend you read everything but I will underline the key points

The compass sensor works very much like a normal compass. This is both a good and a bad thing. The good side to it is the compass has been around for a very long time and has been proven accurate, that is when it is not being acted upon by an outside force other than the earth’s magnetic pull. The bad side is you want to put this on a robot that runs on electricity and it moves around.

The two main problems that you will have to account for in the design process are magnetic fields and stability.

A magnetic field is generated whenever electricity moves. So the cables that connect the sensors and motors to the NXT produce a small magnetic field (the more power demanding sensors will make the wire’s magnetic field slightly bigger. The same thing will happen when you add more power to the motor). The motors themselves emit the biggest magnetic field; this is due to them having magnets in them. The NXT brick will emit the second biggest magnetic fields. Do to all of the magnetic fields I will highly recommend that you build your robot so that the compass is a minimal of 3 to 4 inches away from the NXT and 5 to 6 inches away from the motors.

Do to the fact that the robot will be moving around the stability is very important. The first thing you need to realize is that if the structure is 100% stiff with no movement; yes it is very stable but any and all moment that the robot does will be transferred to the sensor. This will cause the sensor to get inaccurate readings. Also if it is very flimsy it will also be very inaccurate because it will just flop around everywhere. The best way to build it would be to build it with shocks. This would be very hard to do, so the best thing you can do is try to find a midpoint between very sturdy and flimsy.  

 

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