Quote:
Originally Posted by JVN
Anybody have anything quantitative to share? Anybody? Anybody? Bueller?
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OK.
We drove wide, skid steer with a purposely shortened (14" center to center) wheelbase so that we would have less scrubbing while turning. With our CG just forward of the rear set of wheels this gave us excellent turning and control without reducing the standard ~15 LBf thrust allowed by the rover wheel CoF. Interestingly enough, we're not tippy either ... although I wasn't to worried about tipping with the low CoF this year.
We used a single CIM on each side, directly (through a toughbox) driving the rear wheels and chained to the front wheels. This gave us a safety margin should we throw a chain (not expected ... but one of the highest DFMEA values)
Additionally we gave our driver the ability to control the power curve to the wheels and thrust limiting, this allowed him to control wheel slippage as needed.
Next we added two 16" triblade propellers which added ~4.5 LBf each. These were reversable (although less efficient in reverse) and assisted us in direct line (forward and reverse) as well as turning. With this extra thrust we would overcome the trailers friction, thus the tail (trailer) never wagged the dog (robot).
While thrust for both the propellers and drivetrain were driven off the same joystick, they had different power curves. This allowed us to tune each independently.
The above gave us what we were looking for, in our strategy, The ability to get off the line quickly and the ability to pin (in both autonomous and teleop).