Quote:
|
Originally Posted by Jonathan Norris
The first myth I can see is the idea that they are more maneuverable than a basic tank or 6-wheel drive. The fact is that the majority of the successful robots using a mecanum or holonomic drive systems all have low COG. If you have ever seen a good 6-wheel or tank drive system with a low COG which can turn on a dime. I would argue they are far more controllable and more effective (traction!). Have a look at some of the 2002 (or was it 2003) videos just posted here, and you will see some low bots (SPAM 108) which were blazing fast, could turn on a dime, and seemed controllable. Our robot in 2005 was our first year using a 6-wheel design, because of design faults with our arm we ended up being a defensive bot (in the most offensive oriented game so far  ), that robot didn't score much but was fast and maneuverable for defense.
Another fact is that having a high COG with a mecanum or holonomic drive system will cause horrors to the controllability of the robot, because all 4 wheels need to be on the ground (with relatively equal pressure on them) to work properly. I have heard teams argue that these systems allow them to be more maneuverable and therefore better offensively. But in the era of FIRST where the majority the scoring is up high, this will cause havoc for teams trying to use these types of drive systems. I have yet to see a strafing drive system (other than crab, I like!) that can out perform a tank drive or 6-wheel system while still having an offensive robot (presumably with a high COG). |
One word, strafing. The ability to move sideways is the inherent advantage to the "omni-directional" drivetrains (such as mecanum). That is especially advantageous in maneuvering through narrow spaces or when quickly correcting direction or orientation. The most cited con to omni-directional drivetrains is their weaker pushing power (which is true), but they are often rather difficult to be pushed as well (if they are attempting to resist the opposing motion).
As for the CoG, the rest of the bot should have little dependance on what drivetrain you impliment, and thus the CoG shouldn't be terribly effected depending on your drivetrain. But even with higher scoring games, you can still have a low CoG, especially if the robot design doesn't recquire you to elevate any components until your in scoring range (or near it).
I'm also wondering why you angeled the gearboxes.