Force resistive sensor connection

Technology
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1

I want to use the FSR sensors to measure pressure under foot but I do not know how to connect it. I already used some soldering directly… but the plastic melts.

Do you have any trick ?

FSR.jpg816×612 240 KB

2

Soldering directly in a flex is a tricky thing, I think is a hack.
The better way is to use this kind of connectors :

But you will need a small adaptation board…

Anyway, the best methode for soldering directly on a flex is to use flux used to conduct heat.
Place flux on contacts and weld with a soldering iron not too hot.
You also can add a conductive surface like aluminium plate. Place it under your FSR during the operation.

1 Like
3

Thanks, I cannot tune the temperature of my soldering. I will try the aluminium plate.

4

@Nicolas : Are you sure this kind of connector can be used in that case? I hope you’re right :slight_smile: This would simplify a lot of things for the integration on Poppy :slight_smile:

5

This kind of connector is for standard flex PCB. I already seen this kind of things in Nao’s foot, but I don’t remember if there had custom FSR or not…

6

@Thot did you consider the use of a Sensor Film Kit ? I am not sure about the sensitivity with a load during the step but based on the diagram they provide I think it will be more than enough. I think it will be more flexible and we can easily create a grid under the foot.

The only problem I can think of, is the constraint on the number of “analogReads” (in the case of an arduino implementation) . But then again you can have 5 FSR at the shape you want at a price of 15$.

And the connection shouldn’t be a problem (to be on topic :wink: )

(btw, question to Poppy team, on your papers you are referring to use of 8 FSR sensors on each foot. How are you reading these sensors? )

7

Thanks for the link, it is very interesting to replace the FSR sensors. Concerning several analog input for arduino, you can use multiplexers. For each analog input of arduino, you can plug 8 channel. Then you switch the channel every 10ms. The result is 64 analog input for an arduino.
Analog multiplexer are expensive about 11€

8

I am using FSR Interlink 402 sensors, the same used by the Poppy team and i am wondering to know how are you reading data from this sensors and what did you use ?

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I think they used an Arduino to read the datas of the sensor.