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  • Author Author: hawkeyethehacker
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SFH: Week 2 - The Build

hawkeyethehacker

The Safe Field Hockey project is a compact and modular design that can be modified to fit all sizes of human (or other animal, if that's the kind of thing you do image), by simply removing and adding pieces. An example of this is the chest strap that holds the pack, which is located on the left of the body, above the hip.

 

I'll split the explanations of the system into two parts, the base and the uniform.

 

Base

The overall composition of the Base unit depends on the school's or sport club's networking setup. In general, this is the basic outline:

  • Raspberry Pi Model B+
  • WiFi Access Point (Of appropriate range)
  • WiFi Adapter over USB (or USB Ethernet module) *
  • Ethernet Switch *

 

* These are optional. In a larger deployment the Pi and Access Point may be connected to either a dedicated switch for the system, or into the site's network backbone. If the school/club is limited to a single WiFi access point or Ethernet endpoint, however, the Pi may take an internet connection through a USB WiFi/Ethernet module, with the access point connected to the onboard Ethernet port.


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While there is not much difference in the setup, it all boils down to a matter of preference. They both work exactly the same way. What should be noted is that in terms of expandability, going with Deployment Option 2 would be easier. The Raspberry Pi acts as an endpoint for the uniform and mobile app, so everything is unified onto one piece of hardware.

Where this system really shines through though, is the ease of use involved when initially setting up the system. The coach can connect his Android powered Phone/Tablet to the system's WiFi Access Point (which has a password to maintain security, mind you), and launch the SFH app. The app can detect what network it is connected to, and if it is indeed connected to the SFH AP, it will automatically pull the data from the system. No need to configure IP addresses or further usernames and passwords. Even if it is not on the AP, but rather another AP on the network (for example, a school's Bring Your Own Device platform), it can autosearch for the Pi on the network, and authenticate against it for external access. If all else fails - an IP address can be entered. Due to WebSockets being utilised on the app, however, Cellular connections are NOT supported, and if the app detects it is connected via a cellular service, it will not allow the user to connect. Addendum: The issue regarding WebSockets was a lack of research on my part. In general, however, most UK mobile providers will not support such a protocol, and is why I am not implementing cellular connections.

 

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The app is designed in the simplistic Ionic Framework which is powered by AngularJS. Behind the Ionic platform is Apache Cordova, which should allow for future deployment to an iOS device. It is critical the app is simplistic, so the coach can reach the information he requires quickly and easily. Cordova helps open up the possibility for multiple platform support, with minimal adjustments.

 

Uniform

 

The Uniform is where things get exciting.

 

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As shown above, various sensors and boards are placed in different areas of the body. The temperature sensor (ADT7420FBZ) is part of a sweatband that fits onto your wrist, Piezoelectric elements to measure impact are on the shinpads, and an accelerometer is attached to a strap which in turn holds a 3D Printed pack onto your side. This pack holds all measurement PCBs and..... Drumroll Please...

 

The mystery Breakout board and Chip is the Electric Imp!

 

The Electric Imp is an all in one package that is in the package of an SD card. It has WiFi built in and plenty of I/O, including Analogue, Digital, Serial and I2C.

 

All of the sensor output goes to the input of the Electric Imp, which in turn reads them, compiles the readings and sends them to a Node.JS web server on the Pi. The Pi in turn processes the data into a readable form for the app.

 

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This was just a quick overview of what the project entails, and I will be going into more detail as time goes on. Thanks for reading!

 

EDIT: It has come to my attention that I missed the ECG system in the diagram above. Heart rate monitoring works over standard 3 probe electrodes on the chest.