Re: What type of drive train is the most maneuverable?
 

A look at 610 from this year would be worthwhile, too. Very nice use of 6WD and grippy stuff on the wheels.

Re: What type of drive train is the most maneuverable?
 

For a defensive/offensive combo, Swerve would be the cream of the crop, but also expensive. The "best buy" for an agile defender would probably be a 6WD.

Re: What type of drive train is the most maneuverable?
 

Our programmers this year actually got the code down to 4 lines... and it was just converting joy numbers to good PWM values.... super efficient.

Most programmers that I've met actually say they're easier to program than a 4-wheel / 6 wheel tank drive, or at least the ones that have used them.
Only a very weird configuration would make it harder... like only using 3 wheels :p

As for making it go relative to the driver, thats where it becomes tricky (all that great vector math). Thats where we used the gyro, and thats how our robot messed up (preseason, the lead programmer then decided that it wasn't worth our time).

We also found out that a gyro is affected by temperature, pressure, etc. greatly; and that it gave out different readings at different times of the day :( oh well

Re: What type of drive train is the most maneuverable?
 

How would vectors not apply for robot-centric control as well? :confused:

Re: What type of drive train is the most maneuverable?
 

I'm simple. I am a fan of the 4w tank drive, for several years we always went with a width ways orientation so we had a zero degress turning radius. but this last year we had a 4 wheel 2 spd tank that was long ways so to solve the manuverablility problem we implemented a pop-castor design that used a piston to push up the fron and turn on 2 castors and the rear wheels. It looks pretty sweet too!!!

Re: What type of drive train is the most maneuverable?
 

the vector math is easier, and actually is just converting joy input to PWM values (4 lines of code)...

In a stroke of brilliance one of our programmers got rid of all the vectors... and explained "To go left, turn these wheels forward, those ones backward. To go right, turn these wheels backward, those ones forward. To go forward, all wheels go forward, backwards the same. To spin, turn these 2 forward, these 2 backward, and vice-versa" (as he pointed to our diagram).

now (like all other drives) the driver is thinking in terms of the robot, so they're the ones "doing the math".
The robot isn't remembering where it is, so theres fewer vectors involved.

If the robot did remember where it was, the coding would become absolutely atrocious.

Re: What type of drive train is the most maneuverable?
 

if that was true then your gyro was defective or there was a bug in your code reading the gryo value. Solid state gyros are highly reliable, the same AD chips used on the robots are used in cars for things like airbags and stability control (steering).

One thing about the gyros, they must be solidly mounted to the chassis of the robot. If the gyro can wiggle and vibrate (if you hold it down with tie wraps, or foam tape) you will get all sorts junk on the output signal.

To be useful the gyro chip must move exactly the same as the robot chassis moves.

Re: What type of drive train is the most maneuverable?
 

Our 2006 Martian robots were initially designed and built with the same knobby pneumatic skid steer drive train layout we had in 2003,4, and 5. This proved to be too unstable during turning because of the robots’ higher center of gravity. The diagonally placed omni wheels were installed very late in the build. Omni wheels are fine for maneuverability, but not good for resisting a lateral push.

If we had it to do over again, we would have had a drive train very similar to what 469 did this year (and what we did in 2001 on our first Martian robot). Las Gorillas had a skid steer with a set of deployable ball casters on the front right and left to lift the front of the robot off of the ground for maneuverability. When the casters were retracted, all four knobby pneumatic tires were on the ground for impressive pushing power and sideways stability against an aggressor.

Re: What type of drive train is the most maneuverable?
 

What are the joystick controls you use? I can see that the robot can slew around very easily, but what if you really do want to face the robot to a different heading?

Re: What type of drive train is the most maneuverable?
 

When HOT did crab in 2005, we used a regular black Flightstick (forward, backward, left strafe, right strafe) and a Playstation steering wheel to change the robot's orientation.
We just opened up the case of the steering wheel and soldered some wires onto the potentiometer to put into a gameport connector.

Re: What type of drive train is the most maneuverable?
 

Although swerve drive can maneuver around objects, it is not the most physical of drive trains. From what I've seen, the most effective drive seems to be the 6WD.

Re: What type of drive train is the most maneuverable?
 

MORT's best drive train was a 4-wheel.
It used 5" (I think, I'm sure Brandon can correct me) Colson wheels with a very short, wide wheelbase (long robot, short wheelbase) to cut down on scrub. The tipping problems of a short wheelbase were solved with 4 ball casters, one on each corner. It handled beautifully, could get up some decent speed, and was a pretty vicious defender. (I'm pretty sure that robot provoked the no-wedge rule.) Keep in mind however, that this was a flatland drive train for triple-play.
General suggestions based on that bot:
*Colsons rock
*Find the happy balance in the ratio or use a 2speed tranny. (I don't remember what our ratio was.)
*Short, wide wheelbase reduces scrub.
*Ball casters are beautiful on flat land.
*Keep the game in mind. A flat game needs no clearance, a ramp does.

Re: What type of drive train is the most maneuverable?
 

Just an off topic post. If you want manuverable go with a wide robot. Doesn't matter how many wheels you have, it will still be better than a long robot.

Re: What type of drive train is the most maneuverable?
 

All other things being equal, a typical six wheel drive along the long axis will have a shorter effective wheelbase than a four wheel drive arranged on the short axis.

Re: What type of drive train is the most maneuverable?
 

Is there a way to calculate the force (or torque, whatever) required to have a robot turn?