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Measure wheel RPM on an motor cycle — Parallax Forums

Measure wheel RPM on an motor cycle

linuxntlinuxnt Posts: 4
edited 2011-04-11 05:41 in Accessories
Hi:

I like to measure RPM of the wheels of a Enduro / Moto cross / Dirt track motor cycle. Both wheels if feasible (in an attempt to detect bad traction & over acceleration etc.)
What methods and sensors do you suggest?
I have seen Hall effect sensors mentioned for RPM in this forum, would that work here?

One thing to mind, is the physically hostile enviroment with water, mud and even stones, rocks and tree branches trying to remove whatever objectsI like to place. On other hand, if they aren't expensive, I may very well accept a certain rate of loss.

Please see this as brainstorming - Tell me whats on your mind, even if it sounds crazy (many good ideas comes this way) - I appreciate every try :smile:

Cheers:

Comments

  • ercoerco Posts: 20,256
    edited 2011-02-17 13:16
    Hall effect sensor could work, or even a magnet on the wheel spokes and a reed switch on the fork, just like a bicycle computer uses.
  • jim N8RHQjim N8RHQ Posts: 85
    edited 2011-02-21 18:19
    late model Harleys with ABS use a hall effect sensor built in to an axle wheel spacer to read a magneticaly encoded bearing. I can get you the bearing ID and OD and probably the sensor thickness if you think it will help. so, are you planning a servo the keeps you from closing the throttle thereby preventing a low side from becoming a high side?
  • sidecar-racersidecar-racer Posts: 82
    edited 2011-03-02 09:19
    Linuxnt,
    I am working on a similar project for a Bonneville Salt flats sidecar. I am using wheel speed sensor from Aim Sports. I am guessing that your bike has disk brakes ( I am a old MXer) The sensor is a hall effect unit but does not require an external magnet. It triggers by steel proximity; in my case the bolts that fasten the disk to hub. It looks like a bolt with a cable coming out the opposite end. You could fab a bracket on the axle spacer to position the sensor near (1mm or so) the bolts. For protection, you could make an aluminum "cup" that bolts to disk bolts and just clears fork leg, protecting the cable would be the challenge. I plan to use a propeller (C3) with one cog doing counts (from OBEX) for both wheels and tach as part of a data aquisition system. Traction control is one possible result with traction being such an issue on the salt.
    Rick
  • Ray0665Ray0665 Posts: 231
    edited 2011-03-04 15:20
    Hows about the Peizo (parallax 605-00004) flapping against the spokes
    Ought to last about 2 revolutions....
  • kwinnkwinn Posts: 8,697
    edited 2011-03-04 22:20
    For this type of application a hall effect sensor is the way to go. No other sensor I am aware of will stand up to the vibration, dirt, and abuse.
  • sidecar-racersidecar-racer Posts: 82
    edited 2011-03-25 12:14
    Linuxnt,
    Here is a link to a fabrication using Parallax's Hall Effect sensor.
    http://s2kev.blogspot.com/2008/08/motor-rpm-sensor.html
    Rick
  • londevittlondevitt Posts: 2
    edited 2011-03-29 12:27
    Hello All,

    This is my first post in this forum so if I am out of line please just say so and I won't take it badly.
    My question is this: Does it make sense to try and use a Hall effect sensor to try to measure the length of time that a (roller skate) wheel spins given a known and standardized force vector?

    This meant to be a bench test and not something permanently in place on the wheel in normal use; If I am correctly understanding what I have read about Hall effect sensors, I would need to attach a magnet to the wheel to use a Hall effect sensor and while this is possible, it is not preferable. Is that true?

    Simply put, I want to measure how long a (roller skate) wheel spins after a known and standardized force vector is applied to it. The purpose here is to find wheels that have high friction and thus are less efficient. Ultimately I want to use a sensor to control a timer to clock this metric.

    Thank you for your time and consideration,
    \Lon.
  • Ray0665Ray0665 Posts: 231
    edited 2011-03-29 12:41
    Yes that will work. I don't know what affect the magnets would have on length of spin due to unbalancing or extra weight.
    Since this is bench testing perhaps an optical method might be better, by painting stripes on the wheel itself and using something like the QTI sensor would be a better method.
  • londevittlondevitt Posts: 2
    edited 2011-03-29 15:58
    Thank you Ray, I will look into QTI sensors.
    \Lon.
  • FranklinFranklin Posts: 4,747
    edited 2011-04-03 11:39
    linuxnt, is this still unresolved?
  • linuxntlinuxnt Posts: 4
    edited 2011-04-11 05:41
    Hi all! Sorry for beeing away from here for such long time, but ..ahh .. life happend (to get other things on my poor head).
    Anyway - I have browsed through the answers and I think Im happy with the ideas there. Many thanks!
    Franklin wrote: »
    linuxnt, is this still unresolved?

    How do I change this to resolved?
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