Measuring strain on a bike frame
Hi new to the forum, I'm currently working on a project to measure the strain on a bike frame and store the data. I will be looking to use between 6 and 10 strain gauges on this project. Is this something that will be do-able with a raspberry pi? also seen the propeller hat attachment would this be needed?
Re: Measuring strain on a bike frame
Pi has digital input. Is your gauge digital? If not, you can use interface circuit or Arduino. There are many posts on analogue to digital.
Re: Measuring strain on a bike frame
Strain gauages are not that easy to read. You will certainly need additional hardware and probably you should choose some that is designed specifically for strain gauages. The Raspberry Pi can read from I2C and SPI interfaces easily.
You could look at this: https://learn.sparkfun.com/tutorials/lo ... okup-guide
...although I don't think the interface is quite SPI compatible it would be fairly simple to use.
You can also get HX711 boards cheaper from China, for example BangGood, if you don't mind minimal support and a long wait.
You could look at this: https://learn.sparkfun.com/tutorials/lo ... okup-guide
...although I don't think the interface is quite SPI compatible it would be fairly simple to use.
You can also get HX711 boards cheaper from China, for example BangGood, if you don't mind minimal support and a long wait.
Re: Measuring strain on a bike frame
Hi smiles123,
Very interesting project!
There are many sensors available, see for an overview this link:
https://www.electricbike.com/torque-sensors/
for strain gauges this link:
https://www.hbm.com/nl/0014/rekstroken
The sensor (in one of the branches of a wheatstone bridge) converts a torque/strain into a small voltage.
You need to amplify the voltage with a low drift instrumenstation amplifier and digitize it with an analog to digital converter. Use a bus system to read all values of your adc's such as i2c or canbus.
National Instrument (labview) has a very nice program to do all your programming.
Success with your project!
Very interesting project!
There are many sensors available, see for an overview this link:
https://www.electricbike.com/torque-sensors/
for strain gauges this link:
https://www.hbm.com/nl/0014/rekstroken
The sensor (in one of the branches of a wheatstone bridge) converts a torque/strain into a small voltage.
You need to amplify the voltage with a low drift instrumenstation amplifier and digitize it with an analog to digital converter. Use a bus system to read all values of your adc's such as i2c or canbus.
National Instrument (labview) has a very nice program to do all your programming.
Success with your project!
Success with your project!
Ferdinand
Ferdinand
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tenochtitlanuk
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Re: Measuring strain on a bike frame
Sounds a fun and very do-able project.
Note that strain gauges measure strain, ie ( we hope elastic-) deformation. It will be hard to deduce the actual stress producing the deformation, so you can't really see if you are reaching stresses near the elastic limit. If you see PERMANENT strain then you are already in trouble!
A good start is to interface a SINGLE gauge, ie not a balanced bridge, and a standard op-amp circuit, to get a feel for them. I had a lot of fun years ago mounting a single gauge to a hacksaw blade, clamped one end, and with a mass at the other end, and producing graphical output. You can add damping, etc easily.
Thee bike project could be interesting- seeing where the strains are greatest at various phases of the pedal cycle. Are the strains much greater when you stand to pedal? etc.
Note that strain gauges measure strain, ie ( we hope elastic-) deformation. It will be hard to deduce the actual stress producing the deformation, so you can't really see if you are reaching stresses near the elastic limit. If you see PERMANENT strain then you are already in trouble!
A good start is to interface a SINGLE gauge, ie not a balanced bridge, and a standard op-amp circuit, to get a feel for them. I had a lot of fun years ago mounting a single gauge to a hacksaw blade, clamped one end, and with a mass at the other end, and producing graphical output. You can add damping, etc easily.
Thee bike project could be interesting- seeing where the strains are greatest at various phases of the pedal cycle. Are the strains much greater when you stand to pedal? etc.
Re: Measuring strain on a bike frame
Thanks for all your replies, The plan for the project is to have resistive strain gauges within a wheatstone bridge circuit connected to the board through an inverting op-amp. I haven't used a raspberry pi before and was just wondering if it'd be do-able through one. Going to try get my hands on one to have a play around before commiting to using one.