Stealthy Index Finger Throttle/Regen Variable Pressure Button

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hillzofvalp   1 MW

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Stealthy Index Finger Throttle/Regen Variable Pressure Button

Post by hillzofvalp » Nov 25 2019 4:55pm

Once upon a time I bought a whole bunch of FSR 400 sensors and now I'm looking to sell them. They are hard to sell as standalone parts. They are the kind without the crimped connector because I was interested in mounting them to PCB directly with 3M Z-axis tape (3703?). The crimps limit the usefulness as the connector takes up space.

They were originally intended for an electric skateboard throttle.. But since then I have wondered if it would be good to be used as a index finger throttle on an ebike. It would be a 1cm wide thing clamped between the brake mount and the grip.. The fsr would point down towards the ground.

Anyone envision this working well for throttle? it could be pretty tiny and slick.. cost like $30-40 once assembled.. Could also be used for regen braking. I've found that if you build up a silicone button just above the tiny sense area that's all you need to get good feedback. Large sensors are unnecessary and take up space...

Please help me determine the optimum location for the sensor. Grip diameter survey:
https://forms.gle/sTfDLV2ofH4Tis4r5

Here is the latest CAD. Please feel free to print and test the ergonomics.
https://drive.google.com/open?id=1cn1Io ... 8EPcj3wsB_


data sheet:
https://cdn2.hubspot.net/hubfs/3899023/ ... et_FSR.pdf
integration guide
https://cdn2.hubspot.net/hubfs/3899023/ ... ies_IG.zip

It's this part minus the crimps:
Image

Looks like this:
Image
Last edited by hillzofvalp on Dec 12 2019 4:26pm, edited 6 times in total.

tony5haw2013   10 mW

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Re: Interlink FSR 400 Based Throttle -- Design Brainstorm

Post by tony5haw2013 » Nov 25 2019 5:14pm

So how would this work? Looks like they are flexible? Not sure what im looking at ij all fairness but getting rid of bulky throttle would be amazing

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hillzofvalp   1 MW

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Re: Interlink FSR 400 Based Throttle -- Design Brainstorm

Post by hillzofvalp » Nov 25 2019 8:33pm

Here's the general idea. You'd have to cut a small hole or slot in your grip end flange near the clamping area. The little bump is where the throttle is. It could be more pronounced, but I think this will just about do.

If you'd like to 3D print it and test the ergonomics, I can link the cad.

Image

Image

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Re: "INDEX THROTTLE" - Interlink FSR 400 Based Throttle/Regen Button- Brainstorm

Post by amberwolf » Nov 26 2019 12:30am

This might work as a good sensor on a brake lever for proportional regen.

Do you think it would be able to provide significant range of output before the brakes (cable-actuated Avid BB7 in my case) begin to apply noticeable / significant mechanical braking?

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Re: "INDEX THROTTLE" - Interlink FSR 400 Based Throttle/Regen Button- Brainstorm

Post by fechter » Nov 26 2019 9:11am

Those sensors don't like being folded or even curved unless the radius is very large. They also need to be vented and the vent would need to be protected against water ingress. I have a bunch of similar sensors from another project. You may need a simple circuit to linearize and scale the output. My guess is it will tend to be twitchy at the low end.

It might work pretty well for regen control, as sensitivity is less critical. It might also be good for a totally stealth throttle that's integrated into the grip or other part on the handlebars.
"One test is worth a thousand opinions"

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hillzofvalp   1 MW

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Re: "INDEX THROTTLE" - Interlink FSR 400 Based Throttle/Regen Button- Brainstorm

Post by hillzofvalp » Nov 26 2019 1:14pm

amberwolf wrote:
Nov 26 2019 12:30am
This might work as a good sensor on a brake lever for proportional regen.

Do you think it would be able to provide significant range of output before the brakes (cable-actuated Avid BB7 in my case) begin to apply noticeable / significant mechanical braking?
I didn't really envision it being actuated by the lever. That would require a lot of customization depending on the lever and particular setup. Although I suppose it could be moved into a position nearer to the lever, behind the lever, so you could reach your index finger around the lever and to the regen button so your hand was always ready to squeeze the lever for mechanical braking.
Last edited by hillzofvalp on Nov 26 2019 1:23pm, edited 1 time in total.

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Re: "INDEX THROTTLE" - Interlink FSR 400 Based Throttle/Regen Button- Brainstorm

Post by hillzofvalp » Nov 26 2019 1:21pm

fechter wrote:
Nov 26 2019 9:11am
Those sensors don't like being folded or even curved unless the radius is very large. They also need to be vented and the vent would need to be protected against water ingress. I have a bunch of similar sensors from another project. You may need a simple circuit to linearize and scale the output. My guess is it will tend to be twitchy at the low end.

It might work pretty well for regen control, as sensitivity is less critical. It might also be good for a totally stealth throttle that's integrated into the grip or other part on the handlebars.
There wouldn't be any folding or curving... would stick flat on a pcb. I'm not sure the linearization would be necessary. Need to test which range. I don't think the force for max will be greater than about 2-5N

Amalgamating shrink might be the best way to seal the sensor. As long as air can't get out, a vacuum can't be created. It would take a lot of vacuum to depress it enough to matter. In the past I've wrapped the pcb + sensor with kapton and never noticed a vacuum causing issues

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Re: "INDEX THROTTLE" - Interlink FSR 400 Based Throttle/Regen Button- Brainstorm

Post by hillzofvalp » Nov 26 2019 1:31pm

0-500grams is mostly linear using 3k with 5V supply

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Re: "INDEX THROTTLE" - Interlink FSR 400 Based Throttle/Regen Button- Brainstorm

Post by Grantmac » Nov 26 2019 2:10pm

If you could install that on the front of the rear brake lever in a position where braking activated it that would be slick.

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hillzofvalp   1 MW

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Re: "INDEX THROTTLE" - Interlink FSR 400 Based Throttle/Regen Button- Brainstorm

Post by hillzofvalp » Nov 26 2019 3:55pm

I think it would work out that way if it was designed for select few levers with a defined range

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Re: "INDEX THROTTLE" - Interlink FSR 400 Based Throttle/Regen Button- Brainstorm

Post by hillzofvalp » Dec 12 2019 4:23pm

Low interest?

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