Re: Acceleration profile of mice

[Peter Harrison <peter.harrison@helicron.net>]

Matthew Cattle wrote:
> I'm using stepper motors. I have experimented with constant 
> acceleration. I found that my mouse seems to slip when first 
> accelerating from rest, but then accelerates slowly when aproaching its 
> maximum speed. An e^x graph seemed to be the solution, but calculating 
> the delay values for the microprocessor is proving difficult. Should I 
> just stick with constant accleration?

So it would seem you are accelerating too fast at the beginning and then 
not fast enough?

If that is the case, you do not have constant acceleration. Pretty well 
by definition, with constant acceleration, the speed increases linearly 
with time. Note that is time, not distance. So v=at. All the actions 
with a stepper driver tend to occur at discrete step intervals and so 
depend on distance traveled not time elapsed (there are other ways to do 
it). If you have a look at this page:

http://micromouse.cannock.ac.uk/motors/stepper_driving.htm

About one third down is a section called speed control that describes 
how to calculate the timer values. Have a read of that. If it does not 
help or you are using fixed time intervals for your stepper driver, then 
come back and ask again.

Pete Harrison