[python] python stability, again...
- From: mtb@xxxxxxx
- To: python@xxxxxxxxxxxxx
- Date: Sun, 30 Oct 2005 01:32:17 -0700
I have made a couple of mods to the Frame Geometry and Stability program.
http://rjs.org/Python/FrameGeometry.zip 2.8MB
You can modify the wheel sizes visually and set the max speed to analyze.
What I was then noticing was how much the size of the front wheel affects
things. By adding a few kilos to the front rim (lots more mass) the
possible stable speed range drops (ex. stable_1.cfg). Of course, there are
a number of effects all related to the front wheel, like being able to move
the pivot closer.
One of the most important things seems to be how much the mass of the
feet/legs on the pedals helps stability, which is fairly intuitive -
imaging trying to coast with your feet off the pedals and steering with
your handlebars - the python does not want to turn. I've tried!
At large trail numbers, self-stability seems less sensitive to pivot angle
than other factors. If the pivot angle lessens the trail, that is a bigger
effect.
Unfortunately, the program does not model how the bikes "feel" in the
general sense...
I tried to model Dirk's 20", and it seems it can be close to self stable
with some reasonable, small, pivot input from the rider (torsional K in the
model).
I want to mount my vid camera on my back rack tomorrow for a weekend ride.
We'll see...
Vids are also now in the Internet archive:
http://www.archive.org/search.php?query=python%20recumbent
I also just noticed the a Google search for recumbent+python puts my page
on top! http://www.google.com/search?q=recumbent+python
Cheers,
Ray
[front]
fmassheight = 48
frontmass = 22.7
fmassheight_min = 25
fmass2pivot_min = 0
wheelmassf = 0.7
ksteer = -1
ksteer_min = -100
fyp = 1
alphaf = 45
fmass2pivot = 42
wheeldiameterf = 50.8
fmass2pivot_max = 71
fmassheight_max = 89
ksteer_max = 100
[main]
wheelbase_min = 99
wheelbase_max = 150
pivotang_min = -10
wheelbase = 111
trail_min = -41
trail = -14
pivotang_max = 110
trail_max = 20
measure = metric
pivotang = 60
[display]
clearance_min = 5
maxspeed = 96.5
pivotheight = 22
pivotheight_min = 5
clearance = 21
clearance_max = 84
pivotheight_max = 84
[rear]
rmassht_min = 10
alphar = 60
rmassht = 43
wheeldiameterr = 50.8
rmassht_max = 140
masstorear = 48
masstorear_max = 130
rearmass = 75.5
wheelmassr = 0.7
masstorear_min = 10
ryp = 1
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