I am in Year 12 at Parkes Christian School and making a major work that i can track where i am hitting a cricket ball on a bat. similar to what hot spot is and to be able to relay the information on the position to a phone via Bluetooth
(video to help with what my idea is)
At the moment i have ordered a Raspberry pi for the help transmit the data, EeonTex Pressure Sensing Fabric, EeonTex Conductive Fabric.
But i dont know what else i would need so i can get the information of the position to a raspberry pi like what types of thread do i or is there some thing else i need as this is my first time making something like this
Sounds like a great project underway. From what I understand, an Infrared Camera is used to determine where the ball hit the bat. Upon impact, the ball will leave a hotspot on the bat, which can be observed via the elevated IR emitted from that spot (impact=heat=infrared energy).
Fabric may not stand up to all the forces involved - one or two hits in and it’ll be fairly unreliable.
I was then following up with how could I make this work and what would I need to do it if even if I only use tennis balls just for training purposes because we are only looking for the position. And if I have the conductive thread quite close together to make a closer checkered pattern
I would use infrared but I want to make it so it can be added to a bat and taken of with a hat string type system and not broken if it was placed on the ground in the nets and I would like the infamation to be broadcasted to a phone so in realtime you can locate where the ball is on the bat at the time of impact and display that for a period of time
Using a tennis ball will make things a lot easier. Perhaps you could use strips of pressure sensitive fabric, in a grid layout of sorts (3 vertical columns, broken into 3 horizontal rows, 9 segments all up). More segments if you add more columns/rows.
The constraint you’ll likely run into is Analogue to Digital (ADC) sample speed. Each segment will need to be sampled and most microcontrollers share the one buffer for all ADC channels (one sample at a time). While sample speeds are in the microsecond range, performing many samples one after the other isn’t always a clean snap-shot of instant information.
I’d start by putting a piece of fabric on a wall and throwing a tennis ball at it. Capture the signal on an oscilloscope so you can see the rise/fall of resistance (which will be depicted as voltage when the fabric is wired up as a voltage divider). You’ll have a clear understanding of how long it takes for each signal to come/go.
With that timing in mind, ensure that the sample speed of whatever microcontroller you use can perform all of the samples for each panel. Say the signal is present for 1mS; if your ADC sample speed was configured to 50Khz; then you could make 250 samples within each ball strike event. So that’s beyond perfect - you’ll alwas know which panel(s) change resistance.
You’ll need to test to be sure though; I’m just plucking at numbers. Most microcontrollers can handle 10-50Khz ADC sampling with ease. Perhaps you could use something like the Particle Photon if you wanted to jet-set into a phone app of sorts (as they have great sandbox apps ready to use).
And some info about ADC config for the Particle Photon (ADC can be configured for 93nS which is around 12Mhz - it won’t be accurate for high resistive loads though. I’d make it slower to ensure accuratelyreadings):
@Graham So there is no way for it to be done via Bluetooth because I want to limit the use of the internet and cellular data so Bluetooth can be used anywhere and not chew through data?
Also what will I need to connect the fabric to the raspberry pi zero w?
And what will happen if I was to fibre glass the face of the sock where the piezoelectric fabric is located will it then create a stronger area so it absorbed the Impact of a cricket ball but still track the location?
So there is no way for it to be done via Bluetooth because I want to limit the use of the internet and cellular data so Bluetooth can be used anywhere and not chew through data?
Choose a device that has what you need on it, such as Pycom WiPy. There are just so many options.
Also what will I need to connect the fabric to the raspberry pi zero w?
Take a look at the product pages for the fabric; it’s well described there.
And what will happen if I was to fibre glass the face of the sock where the piezoelectric fabric is located will it then create a stronger area so it absorbed the Impact of a cricket ball but still track the location?
I guess you’ll have to get your research hat on - no one would likely have this info ready for you given how bespoke it is. I’d be interested to hear how you get on with it!
We might be on different pages, but this is more than enough intel to get something going: EeonTex Pressure Sensing Fabric is highly conductive with a surface resistivity of 2K Ohm/sq. Additionally, it features a dynamic range of 5g to 100kg, as well as a data acquisition rate of 500 cycles per second.
So you now know it has a resistance of around 2Kohm per/sq. They have also stated that the resistance change is effective from 5kg to 100kg. Do some light research on how voltage dividers work and you can measure that change in resistance easily. They recommend that 500 samples per second is the fastest rate to sample this material, which will likely suit your project fine.
We have over 40 tutorials for getting started with Pi hardware. Some of which are linked on the product page, and the remainder are here. I doubt you’ll find anyone that has done this specific project where you can just copy/paste code from - you’ll be in for plenty of DIY (and that’s half the fun).
@Graham thank you but i was also concerned how i go about connecting the fabric via conductive thread or something similar to the raspberry pi to i can get the information of the location? as this is my first time with a project like this i know how to code some what in python but im not sure about the transmitting the data and what is needed there i have teachers to help with this but i want to know what you say about everything that i need? and i can use the raspberry pi bluetooth to get the data from the Pi to my phone im just consered aboout from the fabric to the Pi
@Graham if i was to use a conductive thread sown into the fabric or use the conductive fabric as an alternative would i use aligator clips on the fabric to connect it to the raspberry pi zero w or what other products are available for me to use to make that connection? i have very limited knowledge on this as its my first time doining this i am trying to find out everything that i need to know and everything you have said so far has been a bit overwhelimg for me at the moment as i dont know much on this topic
@Graham i have recived my products and working on it now but i need to know how to connect the fabirc so i can get a location sensor on the peizoelectric fabric to the raspberry pi or to another computer so i can begin testing.
@Graham here is a better example posibly of what i want to do with the peizoelectric fabric and a raspberry pi can you recomend to me what i need to connecect up a conductive wire or something else so i can purchase anything elsy to make this happen
@Graham But that is the concept that I want to achieve with the piezoelectric fabric. This is only going to be a prototype for the time for my major work. I just want to know what could be available for me to use to be able to make it work in this way for I can the position/location from even if I just use a tennis ball or soft plastic ball just to have the concept working
I haven’t been on the lookout - I gave some ideas and that’s about the extent of what comes to mind when I consider the moving parts of your project. Perhaps someone else might be able to offer tips.
