[dtengineering]

There are many reasons to keep the weight of structural components as low as possible.

First of all is the aesthetic argument that a strong, lightweight piece is simply more elegant and better thought out than a needlessly heavy piece. This isn't the most convincing argument, but in a contest that focuses on engineering design I believe it is relevant.

On a more practical basis, by building structural components light, you can have more of them... this means that you can get your robot to do more things. For instance if you can shave a couple pounds off your frame, then you can perhaps add an extra motor or manipulator component.

Designing with a focus on weight also prevents last-minute robot diets... I've seen teams have to shed as much as 30 pounds on a Thursday at competition, but in our experience it mostly comes at the end of build where we need to re-inforce or replace one system or component, but don't have room in the weight limit. So we break out the hole saws and start lightening the robot elsewhere. Now we try to design the parts lightweight right from the beginning as it is much easier to shed weight at the design stage than at the "oh sh.." stage.

Building light also allows for changes to components at (or between) competitions... or repairs that aren't as light as the original part. At GTR one year a major component broke and we fabricated a heavier replacement part. Going in to elims we weighed 120.0 lbs. Had we not taken the time to replace the steel machine screws holding the electrical components to our robot with nylon screws two months earlier during build we wouldn't have been able to compete on Saturday afternoon.

Finally, even if you can build absolutely everything you want in to your robot, come out ridiculously under the weight limit, with lots of room for upgrades and repairs, you can improve the performance of your robot by building lighter still. It gives you the choice of either having lower mass for higher accelleration (F=ma applies here too) or adding ballast to lower your centre of gravity and/or improve traction and handling.

Jason