Alt-BEAM Archive
Message #01565
To: beam@corp.sgi.com
From: Bob Shannon bshannon@tiac.net
Date: Tue, 16 Mar 1999 22:50:01 -0800
Subject: [alt-beam] Re: BEAM Suspension, was Pager Motors...
> In a message dated 3/14/99 5:27:08 PM US Eastern Standard Time,
> bshannon@tiac.net writes:
>
> > Try adding a simple spring suspension system to the motor mounts. This
> > lets you select a higher trigger voltage (more power) without energy
> > robbing wheel slippage.
>
> Hmmmm...interesting...How does this work? Can you tell me how I would build
> this?
There are several simple ways to mount your motors on some flexible
material
for a simple suspension system.
You can see several suspension systems at:
http://www.the-nest.com/BShannon/
The main idea is to have springy motor mounts that help keep the wheels
on the
ground. I often use thin leaf-springs that are epoxied to the motor and
to the
frame of the photovore. The weight of the robot partly compresses these
springs
so they push the wheels downward.
When the SE and motor fires, some of the mechanical energy is stored in
these springs
and is returned as the cap voltage falls below the motor operating
point. In this way
I can deliver more energy per SE trigger without wheel slippage.
In the Vore-n-more videos, you can see the photovores body 'squat down'
at the beginning of each 'step', and then return to its normal height at
the end of the step. When the SE fires, some of the motors torque is
used to flex the suspension spring, storing energy that would have been
wasted in wheel slippage. As the motor torque drops off with the
falling voltage, the suspension returns this stored mechanical energy.
It also gives a photovore a really organic looking gait.
I used leaf-spring suspension on several Symets as well as photovores.
The leaf spring bots are Hughie, Triluminary, Zaraam, and Vore-n-more.
The rather unusual photovore Eat-at-Joe's uses a combination of leaf
springs and coil springs to acheive its upright 'walking' posture.
Pure coil spring suspension is used on the Symet 'Chaos'.
You can build a really unusual photovore by mounting a BiCore head on
the top of the motor of a Chaos style Symet. It will move in the
direction the head 'leads' it by shifing the center of gravity. (I'd
mount 3 2224 cells in parallel in place of the 3733 cell on the back of
Chaos's motor, mounging them in the same way as on Triuminary.)
Then you would have a 'headed' photovore with full coil spring
suspension, but it would be a really weird little 'bot.
Now how would you add obstacle sensors to such a thing?
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