Rethinking the Chassis

This post may make my previous post Giant Servos – Will They Work / Are They Worth the Cost? somewhat moot.

I have recently stumbled onto some information that makes it unclear whether or not the Giant servos will work the way we hoped they would. On the site, all of the servos that are able to be upgraded to a continuous rotation servo are given difficultly levels. These levels apparently indicate how difficult it is to modify the servo to make it a continuous rotation servo. Not only would this be a risky task to take on (without any professional experience), it is also illegal as of rule R08.w.
After realizing that the giant servos would not work, I felt very much cornered. The wheels each take up one motor (four total), the lower arm takes up another two, the upper arm (with the new upgrades) will take 2 more motors, the block bucket takes up another, and the flag spinner takes up one more after that. That makes ten DC motors; we are only allowed eight.
To make matters worse, Danny had been sick for the past few days, and was not there to help when I discovered this. I discussed it with Tyler and neither of us felt confident about how to solve the issue. We needed at least one more motor to run the new arm. Coming to the conclusion to take the motor off of some other part of the robot was an easy enough thought to come up with; the real question was where we would take it from.

I called Danny. Funny thing; he will always pick up the phone if you call him enough times. It’s as if he has a sixth sense about the robot, and knows when it’s in distress. When I finally got a hold of him, I asked if he was able to come in and help us out. Surprisingly, he decided that he would wait to come in until the next day (a Saturday where we would be more productive). I still needed his advice, so I instead explained our issue to him.
He agreed that we didn’t have many options, but he felt that we may want to consider taking two motors off of the chassis and running the wheels on a chain drive, with sprockets on the motor and each wheel. In the beginning of the year, I would’ve written this idea off entirely. When the game was first released, one of the reoccurring observations that Jerry, Danny, and I kept making was the prediction that in this game we would see even more defense than last year (see second to last paragraph The Game Reveal: Block Party ). Given the narrowness of the field, I am still surprised that we aren’t seeing more of it. However, since we haven’t seen much defense being practiced at all, reducing the power of our wheel system will hopefully not be nearly as big of an issue.

We have already placed a large order of parts, which include both extra chain and more sprockets. We hope to test the new wheels as soon as the order arrives. With the two extra motors, we will not only be able to run our new and improved arm design, but we should also be able to have a working flag spinner in the back of the robot that will enable us to raise the flag if our alliance partner is a reliable hanging robot. I am incredibly nervous about removing the extra motors, but given our lack of other options, I’m hoping for the best.

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3 thoughts on “Rethinking the Chassis

    • They are – we call them Lego wheels because they’re just regular 4″ tetrix wheels with a type of Lego tire stretched over top of it. It adds a lot of grip, but they wear down pretty quickly.

    • I did a post about the different types of wheels used in robotics and my opinion of each. The Lego wheels are talked about at the bottom and I think the product code is on there as well.

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