AVR-Chat

On Jan 15, 2009, at 8:46 PM, Darren Worley wrote:

>>> Measure the travel of *this* wheel: http://home.hiwaay.net/~dkelly/Husaberg/Pages/4.html
>>
>> No problem - add a reluctance pickup, near the chain, on the front  
>> of the drive sprocket.
>>
>
> I think meant how far the wheel moves up and down in relation to the  
> frame.  Is this for the rear wheel?
>

Front and rear.

> LVDT? or Something simpler -> Concept: mount a 10 turn linear pot  
> with a negator spring and small deep section pulley directly  
> attached to the pot spindle. Wrap 10x with fishing line all sealed  
> in a rubber casing that has a tiny hole for the fishing line to  
> escape as the actuator. Depending on your pulley circumference  
> (x10), depends on linear distance measurable. Wind the pot fully  
> anticlockwise, connect spring, then wrap the line around the pulley  
> clockwise. The negator spring is a constant force spring and as you  
> pull the fishing line it tightens up and applies constant force on  
> the line, and the distance moved is then a linear resistance  
> measurement. Mount the module above the rear plastic guard,  
> (secondary protection against direct mud/stone spray, and gravity  
> works to your favour to some degree) but keep close to the frame  
> then drill tiny hole/slot through guard, seal with second piece of  
> rubber, pull fishing line though and attach to the swingarm via  
> swivel, but closer to the pivot point to keep away from potential  
> sticks etc. Any mud that collects on the string will be wiped of by  
> the rubber seals (similar to the front shock seals). This method may  
> be prone to sticks/stones/sticky mud/ though, but is ultra cheap and  
> easy to do. I'd be interested if you actually do this.
>

Mentioned that in my original post. Thats complex and prone to break.  
Considered optical encoder in place of 10 turn pot. Also need high  
frequency response because am interested in how fast it moves up and  
down. A telescopic tube with ultrasonic rangefinder inside could be  
clipped (or taped) on the bike in seconds. Also a copy of the same  
could be mounted to the front so that front and rear data would be  
from the same kind of sensors.

The tube would be easy to damage but cheap to replace. Could be PVC or  
aluminum.

LVDT can be expensive and delicate when caked with mud.

Design range is 14". Suspension travel is 335 mm rear, 300 mm front.  
13.2" rear, 11.8" front.
http://www.husaberg.com/Specifications.242.0.html

> Re the measuring the levels, have you considered what canon do on  
> their ink cartridges to measure tank capacity?

Not sure the OP's ink is for an inkjet but possibly for a printing  
press.

If I wanted an idea of how much liquid is in a tank, I'd thump it with  
a finger and guess based on the sound.


--
David Kelly N4HHE, dkelly@HiWAAY.net
========================================================================
Whom computers would destroy, they must first drive mad.