| The RCX is the heaviest component of your robot. Therefore it is important that it be placed so your robot is well balanced and won't tip over. When you build your robot's frame, the wheels that are in contact with the ground define the support polygon for your robot. If your robot has 4 wheels, then the support polygon is rectangular. If your robot has 3 wheels, then it is a triangle. A 2 wheeled robot, like a bicycle, has a very small support polygon and is not very stable. |  |
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In order to keep your robot from tipping over, its center of gravity must be inside the support polygon. Since the RCX is very heavy, the robot's center of gravity will most likely be located there.
The RCX's center of gravity can be considered to be directly in the middle of the RCX brick. As long as the center of the RCX remains within the support polygon, your robot will be stable. For the most stable robot, the center of the RCX should be in the center of the support polygon. |
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This robot is poorly designed, and the RCX's center of gravity is outside of the support polygon. As a result, the robot tips over. |
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For this robot, the wheels are very close together, so its support polygon is very small. Even though the RCX's center of gravity is inside the support polygon, any slight push to the side and the robot will tip over. |
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| The height of the RCX also affects how stable your robot is. Robots that have their RCX very low to the ground are more stable because it takes a larger tip-over angle before the RCX's center of gravity is outside of the support polygon. |
| This robot is very unstable because its RCX is very high. It takes a much smaller tip-over angle before the center of gravity goes outside of the support polygon and the robot tips over. |
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