Quote:
Originally Posted by LCJ
This is pretty wild. Really cool idea and thanks for sharing!
What was your inspiration?
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a few years ago we had the idea of using an IVT on an FRC bot. There are enough advantages where it seemed like it would give us a very competitive edge in the competitions. looking online we found nothing though so we started playing with ideas. It took a while but we eventually came to realize that a differential could be used in such a fashion, but the obvious drawback is that it requires two motors per transmission and you would have to run them in active feedback speed control. You simply can't use that many motors and at that time we didn't have the capabilities to pull something like this of so it was put in the back of our minds.
So far we have tried various drive systems and the one we had the most success with is 4 corner holonomic which we used for years. It has a lot of it's own drawbacks though so we always had ideas on new drive systems and tried out different things over the years. We had to keep the maneuverability we were used to but we had to gain in speed and power. The only solution was some type of swerve. We prototyped a shifting swerve last year(of which a lot of parts can be seen on this bot) but when we found out the game had no defense we felt it was unnecessary to give up on the holonomic just yet. Due to this fact we were able to perform like we never had before since the weaknesses of holonomic drive didn't matter in that game and we were able to win the st.louis regional since we spent all of our time scoring rather than fighting other robots.
Well we know bumpers will be required again this year, which means robot on robot contact. From previous years we know that if you have a good scoring bot(which we had in previous years but would always get shut down) the other team will dedicate 1 if not 2 of their alliance bots just to get in your way and do anything they can to stop you. Well we don't want to be stopped. so we're trying to come up with the most effective solution we can think of. One of the issues with any drive system or motor control is you lack any control in the low end due to how the power is varied to the motors. so if you want to go slow or make fine adjustments most of the time you can't unless you over gear it which isn't desirable or spend a lot of time trying to tweak in overshoot/undershoot the best you can with PID control which in the end may still not be enough. So with this design we kill multiple birds with 1 proverbial stone.
As with any design however, it has it's own advantages and disadvantages. While we are aware of some of them already, we decided to build a whole bot to try to determine most if not all of the rest of them with such an implementation.