[python] Re: python stability, again...
- From: "dirk@xxxxxxxxxx" <dirk@xxxxxxxxxx>
- To: python@xxxxxxxxxxxxx
- Date: Tue, 16 Apr 2013 15:16:36 +0200 (CEST)
i don't know the program either, but from that variable names, i reckon that
i.e. "front mass (cog of front part) to pivot distance" is meant to be used,
which seems plausible. The cog of the whole bike is - as patrick says - not
really usefull for dynamic analysis of bike behaviour. The least one would
expect is to separate each part that is able to move in relation to others -
front and rear part. And ideally, add the rider as well to that system and that
is where things get really complicated, quickly...
greetings,
DirkS
> Patrick van Gompel <patrick_van_gompel@xxxxxxxxxxx> hat am 16. April 2013 um
> 14:23 geschrieben:
>
> Hello Peter,
>
> I don't know that program and I don't have answers to all your questions
> about it, but a stable bike is not only about centre of gravity (CoG). Just a
> simple example: you have a bike which seems to be stable with a 100kg load
> right in the middle. Now, take 50kg and put that 1 meter to the rear and put
> that other 50kg 1 meter to the front. Your CoG hasn't changed, but your
> (steering) stability has. For example, I think it's almost impossible to drive
> a Python with a 50kg load on the front near the pedals. Your front end will
> probably flip left or right and your legs won't be strong enough to keep it
> centre.
>
> Keep in mind that CoG is an idea to simplify things. Although it can be used
> to calculate things like the load on both wheels, for stability you need quite
> a bit more.
>
> A good question might be why your other bike isn't stable. Is it because of
> the steering, position of mass or a weak construction?
>
> Hope that helps a bit, but I am sure others know much more about it.
> Patrick
>
>
> > From: peter.svancarek@xxxxxxxx
> > To: python@xxxxxxxxxxxxx
> > Subject: [python] python stability, again...
> > Date: Tue, 16 Apr 2013 13:52:44 +0200
> >
> > Hi,
> > I was looking for bicycle stability calculator becase I ran into problems
> > with stability of my little rowing bike project model. It is model(to this
> > time without drive) where I could change to some degree parametres of
> > steering. But that beast is is not very stable, even if it is possible to
> > ride it. So before I will built final recumbent I must obtain reasonably
> > stable model :)
> >
> > I found this little program on this mailing list (
> > http://rjs.org/Python/FrameGeometry.zip ). I even changed a few values to
> > obtain selfstable bike at 6.4 km/h, but while I understand some of
> > variables, others I don’t understand.
> >
> > Front mass to pivot, front mass to height... Why not give there only data
> > about centre of gravity? While on projected bike will be mass moved(both
> > legs and torso of rider) during driving, the centre of gravity would be
> > more
> > or less in the same position. And centre of mass is what is loading the
> > wheels, isn't it so?
> >
> > what is "tortional K to pivot axis" ? What is inertial factor and "inertial
> > angle of front mass from horizontal"? "inertial angle of front mass from
> > horizontal? Front mass and main mass???
> > Cheers Peter
> >
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