Smart IOT Propane Monitoring Pedestal Using Arduino

Intro

We wanted to make a IOT device to reflect our love for grilling and that is why we made The Smart IOT Propane Pedestal. The device is capable of monitoring the weight of the tank as well as detecting any propane leaks. This all requires creating an Alexa Smarthome Skill, an AWS Lambda function and Shiftr.io to communicate with the MKR1000.

Weight Monitoring

Using (4) 50kg Load Sensors in a Wheatstone Bridge arraignment a Load Cell Amplifier, Logic Level Converter, and Arduino MKR1000 we set up a scale similar to your average digital bathroom scale.

Sparkfun has documented hookup guides that should be referenced.

Arduino IDE Sketch we used the sketch example referenced in the spark fun hookup guide for the load cells titled HX711.ino

https://github.com/sparkfun/HX711-Load-Cell-Amplifier

https://github.com/bogde/HX711

Sparkfun Example , Digital Scale

Example Diagram*Note LPG Sensor Supposed to be connected to analog A0 not DigitalPin.

GAS Leak Detection

A Sparkfun LPG Sensor was also connected to the Logic Level Converter and Arduino MKR1000 to provided basic gas leak monitoring rather then varying levels we kept it simple using T/F either gas is detected or its not. With more time we plan on setting certain thresholds to increase accuracy.

Arduino IDE Sketch/Hookup – we used the code example referenced below:

LPG sensor

Pedestal Housing

The pedestal housing consists of two aluminium pans details available in CAD file. We had these fabricated for us by our friends at www.FuseFab.com out of aluminum sheet metal.

The inner pan is where the hardware components were located and the load cell’s were mounted on top of 3d printed feet to allow for enough room underneath for our Arduino MKR1000, LPG Sensor, LoadCellAmp, LogicLevelConverter, etc. A smaller circular plate was placed atop for the propane tank to sit on.

Tank in pedestal

Inner pan housing hardware components

Inside view

Custom parts and enclosures

Strain Gauge Raised Feet

3d Printed Raised Feet Mounts for each of the 4 strain gauges.

Inside view

CAD Sheet Metal Fabrication

Housing consists of two Aluminium Pan’s Fabricated from 10 Gauge Sheet Metal

Schematics

Generic Layout

Code

Lambda Function

Python

float gas, currentWeight, double propaneLevel
def MAX_WEGHT = 36.6
def TARE_WEIGHT = 16.6


def lambda_handler(event, context):
  # TODO implement
 return 'Hello from Lambda'
 
def isDetected(gas):
  if (gas > 0)
  result = True
  print("Gas Leak Detected!")

  else:
  result = False

  return result

print(isDetected(x))

def checkLevel(currentWeight):
  if (currentWeight <= MAX_WEGHT):
  propaneLevel = currentWeight - TARE_WEIGHT

  else
  print("Careful, your tank is too full!")

  return propaneLevel
  print("The current level")

Amazon Skill

JavaScript

{
  "languageModel": {
    "intents": [
      {
        "name": "AMAZON.CancelIntent",
        "samples": []
      },
      {
        "name": "AMAZON.HelpIntent",
        "samples": []
      },
      {
        "name": "AMAZON.StopIntent",
        "samples": []
      },
      {
        "name": "GetPropane",
        "samples": [
          "check propane",
          "tell me propane",
          "get propane",
          "get current propane",
          "check current propane"
        ],
        "slots": []
      }
    ],
    "invocationName": "check propane"
  }
}

Read more: Smart IOT Propane Monitoring Pedestal