|
Re: Different Drivetrains
We went with a 35" long x 24" wide perimeter with 4 wheels, 12.5 inch pneumatic configured with #35 chain and two AM Tougbox Minis at 12.75:1 with all wheels dead axle and using Tank Drive as the logic. Wheelbase was about 20 inches axle to axle with a 7 inch separation between tires. This might seem fairly straightforward but here is what we did different.
Chassis floor was 7 inches off the ground to mount the wheel axle below the chassis and bumper was 6 inches off the ground to clear the rock wall. However, while crossing most defenses was silly easy, turning was a problem with significant shudder. The wheels were plastic frame and would bend on turning while the tire shell had knobbies with a lot of grip. The wheel frames would bend so much in a turn that significant energy would get released when the tire knobbies released from the carpet causing the bot to literally bounce several inches off the floor on carpet.
So we tried something different, we dropped the front left and back right wheels 1/8 inch simulating a drop wheel config but on the diagonal. This was highly effective in taking a lot of the shudder out. The diagonal list was barely noticeable and proved not an issue in driving straight. But since the wheels were pneumatic and flexed enough to still maintain some contact with all 4 wheels, the bot still shuddered some, just not violently anymore. We found a slick black duct tape and covered the rear wheels to permit them to drift. Turning was no longer a problem and the config was ridiculously effective at crossing defenses permitting us to avoid the Evel Knievel breaching method.
The diagonal wheel drop and tape cover worked remarkably well even on wheels that have a lot of surface contact due to their diameter and any rocking action was practically unnoticeable. I spent significant time trying to find some reference to someone else having done it before to see if there was any insight on the best wheelbase separation and drop height. Could find no evidence that it had been tried before. I joked a couple times that we should call it the East Coast drive.
|