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Journal 3.1 Self-Help Embodiment Design

Dizzy’s Journal Entry (The “self-help” principle in mechanical design)

We had a visit from a mechanical engineering mentor today and told him about Vex’s idea for Function #4 (reorient sticks for AON insertion). During our discussions about how we can just let gravity reorient the sticks for us, some of the team argued that we should use a motor instead so that the driver has some ability to account for unforeseen scenarios.

So, which should we do? Should we let gravity rotate the sticks for us, or use a motor?

The engineer explained to us a principle that all mechanical designs should seek out called “self-help” designs. [you can read about the principle in the EST Foundations curriculum teacher presentation slides, section 7.1] Basically, it says that we should always seek out a solution that helps itself accomplish the task. In our case, if we grab the sticks at the top and then try to flip them over, we’ll have to fight gravity (the entire weight of the stick). Instead, we can grab the stick at the bottom. By doing so, gravity will actually help us rotate the stick. This would allow us to accomplish the task with a  lot less motor torque.

So, the answer is, even if we do use a motor, we’ll still want to hold the stick in such a way that gravity isn’t working against us and perhaps even helps the motor do its task.

I wonder if it is better to grab the stick near the bottom (and let gravity help us rotate it) or grab it near the middle (so we can rotate it both directions more easily)?

This article demonstrates one principle of mechanical embodiment design (Self-Help).

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