View Single Post
  #254   Spotlight this post!  
Unread 14-04-2011, 17:34
JesseK's Avatar
JesseK JesseK is online now
Expert Flybot Crasher
FRC #1885 (ILITE)
Team Role: Mentor
 
Join Date: Mar 2007
Rookie Year: 2005
Location: Reston, VA
Posts: 3,734
JesseK has a reputation beyond reputeJesseK has a reputation beyond reputeJesseK has a reputation beyond reputeJesseK has a reputation beyond reputeJesseK has a reputation beyond reputeJesseK has a reputation beyond reputeJesseK has a reputation beyond reputeJesseK has a reputation beyond reputeJesseK has a reputation beyond reputeJesseK has a reputation beyond reputeJesseK has a reputation beyond repute
Re: Minibot climb rate

Different excercise from Ether's:

Using the second derivative of Ether's equation x(t), the acceleration versus time is:
a(t) = -D*e^(-B*t)
To find out when there's no more acceleration, set a(t) = 0 -- since ln(0) is negative infinity, we basically see that the minibot is always technically accelerating. HOWEVER we can see when it gets "close" to its max. speed by substituting in a very small number for a(t). In my case I chose 0.01 m/s^2 since that's small enough to become "unnoticable" IMO.

Sovling the equation for t, to see when the minibot is no longer accelerating gives us
t = ln(0.01/-D)*(1/-B)

Then we can plug that 't' back into the original equation to figure out the height at which the minibot is no longer accelerating.

Presuming:
  • 0.40" Wheel Diameter
  • 2.35lb Weight
  • 0.8225lbs of friction (anecdotally determined)
  • 2 motors, drive driven to the wheels
  • No slip
The time of acceleration = 0.86 seconds
The distance of acceleration = 5.57 feet
__________________

Drive Coach, 1885 (2007-present)
2017 Scoring Model
CAD Library | GitHub

Last edited by JesseK : 14-04-2011 at 17:39.