Can't set max accel and decel below 0.5

RMP 210, 220, 440LE, 440SE, 440 Omni
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noah.leblanc

Can't set max accel and decel below 0.5

Post by noah.leblanc »

I'm having a problem setting the maximum acceleration and deceleration rates. I can change the values to anything above 0.5 m/s^2 and clearly see the values change in the fram_accel_limit_mps2 and fram_decel_limit_mps2 feedback items. However, when I try to set it below 0.5 m/s^2 the feedback always comes back saying the limit is set to 0.4909999... m/s^2. The CCU Interface Document says these values can be set as low as 0. So far, we're using velocity mapping for control and 0.5m/s^2 is too much for our purposes. Any idea why we can't set the accel and decel values below 0.5? Thanks!

phussey
Posts: 79
Joined: Fri Apr 20, 2012 8:12 am

Re: Can't set max accel and decel below 0.5

Post by phussey »

The minimum acceleration and deceleration is set to 0.05 g (0.4909999 m/s^2) to prevent the user from accidentally setting it to zero. This value was determined by 2 factors,

1. To allow for reasonable coastdown acceleration for acceleration based input mapping
2. At the max speed for static systems the minimum deceleration would result in a 64m stopping distance.

Future updates may clamp the minimum acceleration to get a minimum stopping distance for a given maximum velocity. This has not been implemented yet.
PATRICK HUSSEY
Principal Engineer

STANLEY INNOVATION, INC
www.stanleyinnovation.com

noah.leblanc

Re: Can't set max accel and decel below 0.5

Post by noah.leblanc »

Thanks for the clarification. Once we did more driving around outside it turns out 0.5m/s^2 was just right for accel and a bit slow for decel. I think scaling according to max velocity is an excellent idea by the way.

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