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Unread 21-04-2004, 16:55
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dlavery dlavery is offline
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FRC #0116 (Epsilon Delta)
 
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Re: You write <G34> and <G35>

Quote:
Originally Posted by JohnV_Neun
Better yet... I'll have my driver run the bot around the field and you can TRY to hit it with your sledgehammer. Good luck.
OOOOHHHH!!! File that one away in the "Ideas for the 2005 game" folder!

Quote:
Originally Posted by KenWittlief
if I made a mistake in my potential/kinetic energy equations please point them out, but thats what it equates to - driving a 130 lb bot into another at 15mph is the SAME AS hitting it with a 5 lb sledge hammer going 76mph
Actually, you did make a mistake (or assumption that led to a significant mistake). In the original argument, you stated the kinetic energy transfer of a 130 pound robot traveling 15 mph was equivalent to the impact of a 5 pound sledgehammer face traveling 76 mph. In terms of raw energy transfer potential, that may be true. However, it requires that the impact area of the robot-to-robot collision be limited to approximately 4 square inches (in your example, "catching a corner of the frame"), AND that 100 percent of the potential energy of the moving system be transferred through that impact area. For that to happen, the centers of mass of both robots, the center of impact, and the dymanic motion vectors of both robots would all have to be precisely colinear.

In reality, given the kinematics and dynamics of the typical FIRST robot, that assumption is fallacious. It is highly unlikely (bordering on virtually impossible) that the "impact energy vectors" for the robots (drawn through the center of mass and the impact point of each robot) will be colinear and opposite. The higher the divergence between these two vectors and this "maximum impact energy transfer state," the higher the proportion of translational energy that is converted to rotational energy (i.e causes both robots to spin around their respective centers of mass). In the example of catching a corner, the majority of the energy is dissipated as torque around the center of mass of each robot. The actual amount of energy transferred to the impacted robot is equivalent to kinetic energy * cos(abs(dynamic motion vector - impact energy vector)).

-dave
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