When using a track drive or a SKID-STEER type steering system, how would you move away from the wall if you got pushed side ways against it accidentally?
- J15.5h (TEAM 1247 ROKS) :ahh:
The trick is to believe itās possible.
As a prelude to this post, for the sake of fully explaining myself, I am going go into more detail than needed, but I will bold objects that are most important to the topic at hand.
When using a tank drive (equivalent to a track drive for this purpose), there are a few options of movement. You can move Left Drive(L) Forwards (F) or Backwards (B) as well as not moving (N). This also applies to the Right DriveĀ®. This means that you can have these senarios:
LF RF =forwards
**LF RN ** =curve clockwise to the right with your R as the pivot point
LF RB =turn clockwise with a point between the drives as the pivot point
**LN RF ** =curve counter-clockwise to the left with your L as the pivot point
LN RN =stopped
**LN RB ** =curve clockwise to the right with your L as the pivot point
LB RF =turn counter-clockwise with a point between the drives as the pivot point
**LB RN ** =curve counter-clockwise to the right with your R as the pivot point
LB RB =backwards
This is the list of basic movements for a tank-drive robot non-inclusive of speeds (varying PWM values or gear ratios) and also non-inclusive of choosing between sharp braking or glide-braking with your victorās.
The four options bolded above allow the robot to move away from a wall that one side parallel to itās drivetrain direction is pressed flat up against. This is because the robot drags around the turn and thus means that your pivot point becomes the upper or lower point of contact with the side of the field instead. That is the theoretical easiest way out. In reality, all FIRST robots motors (drill, CIM, fisher-price, van-door, window, etcā¦) are powerful enough to push the robot out in any of the turning configurations barring another robot pinning you there.
I hope this answers your question for you, but Iāve been doing History for an hour (Civil War), so I may be making a few mistakes. Correct at will.
Itās actually not hard, you just drive away from the wall. The way the robots are built, they almost always have more than enough power to push themselves away from the wall, so long as your drivers know what theyāre doing. The most important thing for this is to just make sure your batteries are fully charged, so your robot has plenty of power to push itself away from the wall, as this (along with pushing other robots) is probably one of the more power intensive aspects of a match.
and then of course assuming 1) you have lots and lots of torque. 2) you have plenty of grip to spare. 3) the walls are not bolted into the floor every foot.
then the walls will move. or at least give a little if you are missing either 1) or 2) or maybe both. so you basically dont have to worry about getting stuck at all
*edit. oh right. you are pushed sideways into the wall. nvm 2) then 
well aaaanyways, the REAL question is if you have 2wd but have the drivewheels at the center point of your robot. either you need a lot of torque qith grip or just less grip. either way, unless your robot is a circle, center 2wd is probably the hardest to get away from a āparallel park to the wallā 
My team used BreckoFlex tracks this year and had NO problem. Its relativley easy, say your up agains the player station wall. you can drive straigh with a slight arc and eventually you will have gotten off the wall. OR you can simply just turn left or right and it will āflopā aroundā¦ i use the term āflopā as it does this weird turn i cant explain.
WARNINGā¦
we used and offset idler pully in our tracksā¦so we had less of a foot print to turn onā¦
I HIGHLY RECOMMEND USING A OFFSET IDLER OR RISK THE POTENTIAL OF NOT TURNINGā¦WE FOUND OUT THE HARD WAY!
To also include on this we actually also had a nub on the side of teh frame toowhich allowed use to have a slight turn on the wallā¦enough so that we can get off itā¦it kinda looks like whats below
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This allows you to pivot on that point