Re: Very high changes in acceleration and wheel forces which is not logical

Hi Alan

Do you sample these values in every simulation timestep (500Hz) or from 
the robot (50Hz), what are the conditions for the experiment (track, 
speed, cars, ...). What about averaging to get a better signal (e.g. 
cosider it as noise)? Is all output from the same wheel (just asking)?

For me these values "make sense", you can think of a gear wheel, which 
bounces within its play.

I am aware that the force calculation around speed=0 is a mess there, 
but I did not find so far the time to improve it, e.g. I want to get rid 
of "if v < 0.000001" etc.

The trick will be to add the result of another function around zero, 
this function will need to fulfill these requirements:
- I must be plausible
- It must fade out completely for the ranges where the current model is 
correct
- Ideally there would be no "if" decisions to do anymore.

Best regards

Bernhard


On 02/27/2013 01:50 PM, Alan Ali wrote:
> Hi All,
>
> I am trying to control the vehicles, my control law needs to know
> vehicle acceleration "DynGCg.acc".
> watching this acceleration show that it change very quickly in
> unlogical  way (we don't see all this changes as the speed is the
> accumulation (filteration) of the acceleration and we will see filtred
> response...)
>
> trying to konw the source of the problem :
> i found that the problem is from the forces applied on the wheels
> computed in (void SimWheelUpdateForce(tCar *car, int index)) function
> where the forces change very rapidly in unlogical way
> as un exempl:
>   taking          Car->ctrl.accelCmd = 0.1;
> i get the following forces acting on the wheels:
>
>
>
> you can see that the longitudial force changes very rapidly (eg. from Ft
> =-6360 to 7843) which is not logiacl
>
> Searching more and more to know the problem i have found that it is
> caused as a result of high changes of  sx = (vt - wrl) / fabs(vt);
> which is it its turn change as a result of high changes of wrl =
> wheel->spinVel * wheel->radius;
> so it is very clear that the problem is from high changes of
> "wheel->spinVel" but i couldn't know much more ...
> can any one help me to know why it change rapidly and how to reduce this
> changes as it is not logical.
>
> thanks for all.
>
>
>
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