Spoke sensor for bicycle

On 6/14/2022 8:51 AM, Dimiter_Popoff wrote:
> I started cycling again (used to as a kid...) some 4 years ago.
> And while I know there are plenty of super cheap "bicycle computers"
> I have been thinking of making my own.

As the COTS units are "super cheap", one has to assume you want
to do something MORE -- or differently...

> Thus so far 4 years no speed/mileage indicator for me, obviously.
> While this may likely remain the case forever I am still thinking
> about it - not the obvious things like the MCU, display etc., just
> the rotation sensor. They all use a magnet placed somewhere on one
> of the wheels and some sensor, I have used a Hall sensor for
> pretty precise positioning of the rotor of our TLD reader etc.,
> but I only still keep on thinking of making the thing because I
> imagine it sensing just the spokes, i.e. making some inductive sensor.

You need to consider your goal.  If you simply want to know your
"physical displacement" on the globe, then periodic fixes from a GPS
(with straightline interpolation of route traveled) is a crude
approximation.  Advantage:  you likely are already carrying a cell
phone that could give you that data.  Disadvantage:  GPS accuracy
varies (from moment to moment) as does reception.  Likely won't
tell you you're moving at all if your pedaling in a tight circle!

A variable reluctance sensor noting the passing of one or more
"slugs" on the wheel gives you an idea of rotation -- if you
aren't concerned with direction of rotation (software to filter out
"jitter" if you're stopped and rocking forwards and backwards on
a "sense point").  A magnet and reed switch can do comparable.

Optical ON THE WHEEL is likely not practical due to weather
conditions.

All of these have issues with proximity of sensor -- an out of
true wheel (wobble) could complicate things.

Personally, if I saw some added value to rolling my own, I'd
opt for a "vintage" speedometer's pickup:

<https://i.ebayimg.com/images/g/JkMAAOSws21iGSc9/s-l1600.jpg>

transferring motion through a "cable-in-cable" to a "head
unit" that has been gutted.  Mount a toothed gear on the end
of the cable shaft *in* the head unit and sense rotation optically
or variable reluctance.  Quadrature detector if you want to
be able to note direction of movement for FINE sensitivity.

Electronics mounted on a little board that also supports the
inductive/optical sensors -- display, controls, etc.

This lets you move the electronics (and display) away
from the wheel -- which is likely kicking up mud, water, etc.

> I know what I will try out etc., I may even get to designing one before
> the millennium is over but well, these thoughts seem to be on topic and
> I am sure there are people with more experience making inductive
> sensors than I have.

tirsdag den 14. juni 2022 kl. 21.21.00 UTC+2 skrev Don Y:
> On 6/14/2022 8:51 AM, Dimiter_Popoff wrote: 
> > I started cycling again (used to as a kid...) some 4 years ago. 
> > And while I know there are plenty of super cheap "bicycle computers" 
> > I have been thinking of making my own.
> As the COTS units are "super cheap", one has to assume you want 
> to do something MORE -- or differently...
> > Thus so far 4 years no speed/mileage indicator for me, obviously. 
> > While this may likely remain the case forever I am still thinking 
> > about it - not the obvious things like the MCU, display etc., just 
> > the rotation sensor. They all use a magnet placed somewhere on one 
> > of the wheels and some sensor, I have used a Hall sensor for 
> > pretty precise positioning of the rotor of our TLD reader etc., 
> > but I only still keep on thinking of making the thing because I 
> > imagine it sensing just the spokes, i.e. making some inductive sensor.
> You need to consider your goal. If you simply want to know your 
> "physical displacement" on the globe, then periodic fixes from a GPS 
> (with straightline interpolation of route traveled) is a crude 
> approximation. Advantage: you likely are already carrying a cell 
> phone that could give you that data. Disadvantage: GPS accuracy 
> varies (from moment to moment) as does reception. Likely won't 
> tell you you're moving at all if your pedaling in a tight circle! 
> 
> A variable reluctance sensor noting the passing of one or more 
> "slugs" on the wheel gives you an idea of rotation -- if you 
> aren't concerned with direction of rotation (software to filter out 
> "jitter" if you're stopped and rocking forwards and backwards on 
> a "sense point"). A magnet and reed switch can do comparable. 
> 
> Optical ON THE WHEEL is likely not practical due to weather 
> conditions. 
> 
> All of these have issues with proximity of sensor -- an out of 
> true wheel (wobble) could complicate things. 
> 
> Personally, if I saw some added value to rolling my own, I'd 
> opt for a "vintage" speedometer's pickup: 
> 
> <https://i.ebayimg.com/images/g/JkMAAOSws21iGSc9/s-l1600.jpg> 
> 
> transferring motion through a "cable-in-cable" to a "head 
> unit" that has been gutted. Mount a toothed gear on the end 
> of the cable shaft *in* the head unit and sense rotation optically 
> or variable reluctance. Quadrature detector if you want to 
> be able to note direction of movement for FINE sensitivity. 

how would that  make any sense compared to the simple and ultra reliable reed and magnet?

Rube Goldberg would be proud

On 6/14/2022 12:39 PM, Lasse Langwadt Christensen wrote:
> tirsdag den 14. juni 2022 kl. 21.21.00 UTC+2 skrev Don Y:
>> On 6/14/2022 8:51 AM, Dimiter_Popoff wrote:
>>> I started cycling again (used to as a kid...) some 4 years ago.
>>> And while I know there are plenty of super cheap "bicycle computers"
>>> I have been thinking of making my own.
>> As the COTS units are "super cheap", one has to assume you want
>> to do something MORE -- or differently...
>>> Thus so far 4 years no speed/mileage indicator for me, obviously.
>>> While this may likely remain the case forever I am still thinking
>>> about it - not the obvious things like the MCU, display etc., just
>>> the rotation sensor. They all use a magnet placed somewhere on one
>>> of the wheels and some sensor, I have used a Hall sensor for
>>> pretty precise positioning of the rotor of our TLD reader etc.,
>>> but I only still keep on thinking of making the thing because I
>>> imagine it sensing just the spokes, i.e. making some inductive sensor.
>> You need to consider your goal. If you simply want to know your
>> "physical displacement" on the globe, then periodic fixes from a GPS
>> (with straightline interpolation of route traveled) is a crude
>> approximation. Advantage: you likely are already carrying a cell
>> phone that could give you that data. Disadvantage: GPS accuracy
>> varies (from moment to moment) as does reception. Likely won't
>> tell you you're moving at all if your pedaling in a tight circle!
>>
>> A variable reluctance sensor noting the passing of one or more
>> "slugs" on the wheel gives you an idea of rotation -- if you
>> aren't concerned with direction of rotation (software to filter out
>> "jitter" if you're stopped and rocking forwards and backwards on
>> a "sense point"). A magnet and reed switch can do comparable.
>>
>> Optical ON THE WHEEL is likely not practical due to weather
>> conditions.
>>
>> All of these have issues with proximity of sensor -- an out of
>> true wheel (wobble) could complicate things.
>>
>> Personally, if I saw some added value to rolling my own, I'd
>> opt for a "vintage" speedometer's pickup:
>>
>> <https://i.ebayimg.com/images/g/JkMAAOSws21iGSc9/s-l1600.jpg>
>>
>> transferring motion through a "cable-in-cable" to a "head
>> unit" that has been gutted. Mount a toothed gear on the end
>> of the cable shaft *in* the head unit and sense rotation optically
>> or variable reluctance. Quadrature detector if you want to
>> be able to note direction of movement for FINE sensitivity.
> 
> how would that  make any sense compared to the simple and ultra reliable reed and magnet?

   "As the COTS units are "super cheap", one has to assume you want
   to do something MORE -- or differently..."

He can *buy* the "ultrareliable reed switch and magnet".  Presumably,
that doesn't meet his needs.  It doesn't, for example, register correctly
if the magnet happens to be CLOSE (rotationally) to the switch and
you are stopped -- chatting with someone -- while rocking forwards and
backwards with the bicycle.  (it has no sense of direction)

It doesn't register variations in speed within a single revolution
(e.g., cranking up hill) or the instantaneous WHEEL acceleration from
the rider's efforts.

It also requires the wheel to be true (no wobble) to ensure the distance
from magnet to switch is sufficient to reliably engage -- while not getting
*whacked* by some other portion of the wheel as it passes that isn't
true.

The magnet can be dislodged, sensor alignment botched, etc.  If
you swap out the wheel, you have to remount a new magnet on the
replacement wheel, ensure proper alignment, etc.

And, you're still going to have to run a (electrical) cable up
to some sort of display/control unit.  And, protect that input
to the electronics (i.e., you wouldn't want to directly expose a
pin to that external signal) lest the device die with the first
bit of ESD.

Instead, bring the motion (ALL of it) up to that unit and let *it* decide
what criteria are appropriate to measure.  Instead of cable-in-cable plugging
into the back of a legacy "speedometer" (indicator), let it drive a slotted
wheel/gear mounted on a board already aligned with the sensors (which need
not worry about the same environmental issues that sensing ON the wheel
imposes) and UNBUFFERED inputs to whatever processing/display/control logic.

 > Rube Goldberg would be proud

Most of his designs worked!

On 6/14/2022 12:35 PM, Dimiter_Popoff wrote:
> On 6/14/2022 20:25, Ricky wrote:
>> On Tuesday, June 14, 2022 at 1:16:34 PM UTC-4, John Doe wrote:
>>> Dimiter_Popoff <d...@tgi-sci.com> wrote:
>>>
>>>> I started cycling again (used to as a kid...) some 4 years ago. And
>>>> while I know there are plenty of super cheap "bicycle computers" I 
>>>> have
>>>> been thinking of making my own. Thus so far 4 years no speed/mileage
>>>> indicator for me, obviously. While this may likely remain the case
>>>> forever I am still thinking about it - not the obvious things like the
>>>> MCU, display etc., just the rotation sensor. They all use a magnet
>>>> placed somewhere on one of the wheels and some sensor, I have used a
>>>> Hall sensor for pretty precise positioning of the rotor of our TLD
>>>> reader etc., but I only still keep on thinking of making the thing
>>>> because I imagine it sensing just the spokes, i.e. making some 
>>>> inductive
>>>> sensor.
>>>>
>>>> I know what I will try out etc., I may even get to designing one 
>>>> before
>>>> the millennium is over but well, these thoughts seem to be on topic 
>>>> and
>>>> I am sure there are people with more experience making inductive 
>>>> sensors
>>>> than I have.
>>> This might be blasphemy, but...
>>>
>>> Speed and mileage indication is easily done with a smartphone these 
>>> days,
>>> at least here in America.
>>
>> People often talk about cell phones as if they had universal 
>> coverage.&nbsp; That is true for 99.9% of where people spend their time.&nbsp; 
>> But that 0.1% of the time, like biking in the woods, you are out of 
>> cell phone range.&nbsp; So any solution needs to not depend on a cell 
>> phone connection.&nbsp; If you can use the GPS in your phone without a 
>> cell connection, great!&nbsp; But I haven't found such a program as yet.&nbsp; 
>> Maybe I just haven't dug deep enough.
>>
>
> Oh where I bike there is coverage allright, and I think I had seen
> references to some apps for biking. Looks like the only thing making
> me think of that "project" I am unlikely to ever even start is the
> sensor design.... (I am vague because I am not so sure myself why I
> keep thinking of this every now and then for 4 years and still have
> nothing in use when I bike :).
Google tracks me all over, it knows if I drive, bike or walk. I'm not 
sure the times that has come in handy is worth being tracked.
But at least if a bank is robbed my phone should be able to prove it 
didn't do it.

-- 
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

Okay then, just clip a playing card to the fork.

On Tuesday, June 14, 2022 at 12:40:03 PM UTC-7, lang...@fonz.dk wrote:
> tirsdag den 14. juni 2022 kl. 21.21.00 UTC+2 skrev Don Y: 

> > Personally, if I saw some added value to rolling my own, I'd 
> > opt for a "vintage" speedometer's pickup: 
> > 
> > <https://i.ebayimg.com/images/g/JkMAAOSws21iGSc9/s-l1600.jpg> 
> > 
> > transferring motion through a "cable-in-cable" to a "head 
> > unit" that has been gutted. Mount a toothed gear on the end 
> > of the cable shaft *in* the head unit and sense rotation optically 
> > or variable reluctance. Quadrature detector if you want to 
> > be able to note direction of movement for FINE sensitivity.
> how would that make any sense compared to the simple and ultra reliable reed and magnet? 
> 
> Rube Goldberg would be proud

Two advantages: it knows forward from reverse, and it has angular sensitivity to sub-one-revolution
movement.    It also doesn't need an adjustment-type mount for the sensor, just
slap it around the axle and mount the wheel.   There's nothing to prevent that kind
of axle-mount item from having a magnet and quadrature reed switches, of course; the speedometer-cable
is a bit of a hassle compared to a signal wire.

A better solution would be to instument a hub and axle, but the axle diameter is fixed by the bicycle frame, and
the hub by the wheel-builders.   That means redesigns of the mechanical bits unless one lucks out and
finds a compatible generator hub off-the-shelf.

On Tue, 14 Jun 2022 20:09:26 +0300, Dimiter_Popoff <dp@tgi-sci.com>
wrote:

>On 6/14/2022 18:57, Joe Gwinn wrote:
>> On Tue, 14 Jun 2022 18:51:21 +0300, Dimiter_Popoff <dp@tgi-sci.com>
>> wrote:
>> 
>>> I started cycling again (used to as a kid...) some 4 years ago.
>>> And while I know there are plenty of super cheap "bicycle computers"
>>> I have been thinking of making my own.
>>> Thus so far 4 years no speed/mileage indicator for me, obviously.
>>> While this may likely remain the case forever I am still thinking
>>> about it - not the obvious things like the MCU, display etc., just
>>> the rotation sensor. They all use a magnet placed somewhere on one
>>> of the wheels and some sensor, I have used a Hall sensor for
>>> pretty precise positioning of the rotor of our TLD reader etc.,
>>> but I only still keep on thinking of making the thing because I
>>> imagine it sensing just the spokes, i.e. making some inductive sensor.
>>>
>>> I know what I will try out etc., I may even get to designing one before
>>> the millennium is over but well, these thoughts seem to be on topic and
>>> I am sure there are people with more experience making inductive
>>> sensors than I have.
>>>
>> 
>> .<https://en.wikipedia.org/wiki/Variable_reluctance_sensor>
>> 
>> 
>> Joe Gwinn
>
>Hmmm, but will that work at really low speed (like when pushing the
>bike uphill)? It is an idea to do it this way (I did not even know the
>name of the method so the idea is more than welcome), yet what I was
>thinking was more in the line of changing some oscillation frequency
>(thus detecting the spokes also  "at DC").

Well, there is also Wiegand-wire sensors:

.<https://en.wikipedia.org/wiki/Wiegand_effect>

.<https://en.wikipedia.org/wiki/Wiegand_Sensor>

But as others have noted, the spokes may be non-magnetic.  This can be
solved by adding a bit of zinc-plated mild steel tubing (automotive
brake line) glued to at least one spoke with a silicon rubber
adhesive.  The spoke would pass through an inch of tube, with silicon
 rubber filling the gap between tube and spoke.

Joe Gwinn

Dimiter_Popoff <dp@tgi-sci.com> wrote in
news:t8aapr$ab6$1@dont-email.me: 

> I started cycling again (used to as a kid...) some 4 years ago.
> And while I know there are plenty of super cheap "bicycle
> computers" I have been thinking of making my own.
> Thus so far 4 years no speed/mileage indicator for me, obviously.
> While this may likely remain the case forever I am still thinking
> about it - not the obvious things like the MCU, display etc., just
> the rotation sensor. They all use a magnet placed somewhere on one
> of the wheels and some sensor, I have used a Hall sensor for
> pretty precise positioning of the rotor of our TLD reader etc.,
> but I only still keep on thinking of making the thing because I
> imagine it sensing just the spokes, i.e. making some inductive
> sensor. 
> 
> I know what I will try out etc., I may even get to designing one
> before the millennium is over but well, these thoughts seem to be
> on topic and I am sure there are people with more experience
> making inductive sensors than I have.
> 
  Most out there do not sense every spoke, but instead sense a metal 
flag attached to one spoke and most use a hall effect sensor 
transducer for that.

John Dope <always.look@message.header> wrote in
news:t8afpb$t21$6@dont-email.me: 

> Dimiter_Popoff <dp@tgi-sci.com> wrote: 
> 
>> I started cycling again (used to as a kid...) some 4 years ago.
>> And while I know there are plenty of super cheap "bicycle
>> computers" I have been thinking of making my own. Thus so far 4
>> years no speed/mileage indicator for me, obviously. While this
>> may likely remain the case forever I am still thinking about it -
>> not the obvious things like the MCU, display etc., just the
>> rotation sensor. They all use a magnet placed somewhere on one of
>> the wheels and some sensor, I have used a Hall sensor for pretty
>> precise positioning of the rotor of our TLD reader etc., but I
>> only still keep on thinking of making the thing because I imagine
>> it sensing just the spokes, i.e. making some inductive sensor. 
>> 
>> I know what I will try out etc., I may even get to designing one
>> before the millennium is over but well, these thoughts seem to be
>> on topic and I am sure there are people with more experience
>> making inductive sensors than I have. 
> 
> This might be blasphemy, but... 
> 
> Speed and mileage indication is easily done with a smartphone
> these days, at least here in America. 
> 

With a range of error.  At least unless you are using militsry grade 
hardware and getting military grade resolves logged.

  Phones are slow at keeping up.  Use one riding a bus and you can 
watch the lags in real time.

  Johnny loses the phone on a bus gps test!   Ehhhh!

Record-setting gas prices every day.

Highest inflation rate since 1981 when Ronald Reagan entered office.



DecadentLinuxUserNumeroUno@decadence.org wrote:

> John Dope <always.look@message.header> wrote in
> news:t8afpb$t21$6@dont-email.me: 
> 
>> Dimiter_Popoff <dp@tgi-sci.com> wrote: 
>> 
>>> I started cycling again (used to as a kid...) some 4 years ago.
>>> And while I know there are plenty of super cheap "bicycle
>>> computers" I have been thinking of making my own. Thus so far 4
>>> years no speed/mileage indicator for me, obviously. While this
>>> may likely remain the case forever I am still thinking about it -
>>> not the obvious things like the MCU, display etc., just the
>>> rotation sensor. They all use a magnet placed somewhere on one of
>>> the wheels and some sensor, I have used a Hall sensor for pretty
>>> precise positioning of the rotor of our TLD reader etc., but I
>>> only still keep on thinking of making the thing because I imagine
>>> it sensing just the spokes, i.e. making some inductive sensor. 
>>> 
>>> I know what I will try out etc., I may even get to designing one
>>> before the millennium is over but well, these thoughts seem to be
>>> on topic and I am sure there are people with more experience
>>> making inductive sensors than I have. 
>> 
>> This might be blasphemy, but... 
>> 
>> Speed and mileage indication is easily done with a smartphone
>> these days, at least here in America. 
>> 
> 
> With a range of error.  At least unless you are using militsry grade 
> hardware and getting military grade resolves logged.
> 
>   Phones are slow at keeping up.  Use one riding a bus and you can 
> watch the lags in real time.
> 
>   Johnny loses the phone on a bus gps test!   Ehhhh!
>