There are several applications for monitoring the fill level of bins for holding recyclable discards of various kinds. The idea is to use a LoRaWAN-capable device to monitor the fill level, and other bin “state” data, and notify the bin management service when the bin needs maintenance.
Bin maintenance usually means replacing the bin when full and carting the bin contents away for recycling. But it could also mean detecting when the contents need to be removed before 100% fill because they are generating heat, are too “wet” or smell too much, etc.
It’s hard to capture every case but with something like this Sentinel device:
mounted inside the bin, a BME280 measuring the temperature and humidity can keep track of inside environmental conditions, a BMA280 accelerometer can detect when the bin has been mechanically jarred or tipped over, a VEML6040 ambient light sensor can track when the bin lid is open, and a VL53L0 time-of-flight ranging sensor can track the fill level of the bin, which is the main function.
All of these sensors have been incorporated in a version of this Sentinel device which I am testing now. Average power usage measuring and logging sensor data once per minute and sending LoRaWAN updates once per ten minutes is ~40 uA. At this rate the Sentinel can monitor bin level for more than three years.
Here is a record of the distance from the Sentinel device to a wall in my house for the last week as part of a short-term (~80 day) power test:
The units are centimeters and you can see that the distance recorded is 34 cm plus or minus a few millimeters. The apparent jitter is partly due to diurnal temperature fluctuations in my house. The VL53L0 is a superbly accurate sensor, and certainly accurate enough to alert when a bin is full. The sensor itself is only a few dollars and is easily integrated into any pcb with an I2C bus.
We expect to begin deployment for these kinds of bin level measuring devices this year, with construction sites and hospitals likely first customers.
Sentinel is described in the logs at the hackaday.io link. It is not for sale at the moment, but VL53L0 breakout boards are for sale at Tindie in case you want to try out bin level measurement for yourself.
Typical use case is for recycling containers, where fill rate is unpredictable.
So large “55-gallon drum” sized containers with lids. Also large plastic containers with lids. Recycled materials could be soda cans, construction scraps, hospital disposables, office paper, etc.
May different types means a lot of opportunity for customization, but we expect a single product like the Sentinel to work for most of them.
Not a problem, most plastics though opaque in the visible are transparent in the near IR, i.e., 940 nm, so the VL53L0 is protected from the bin environment by the plastic container.
For the humidity/pressure/temperature measurement, we place a hole in the back with one or more grooves to allow air flow but no bin contaminants inside.
We also have small, cheap patches that are impervious to moisture but allow air to pass (semi-permeable membranes, etc) that we can place over small case penetrations if necessary.
“As a matter of fact there is now a commercially available product utilising ToF for bin level measurement.”
Can you provide a link?
“The battery life expectancy of 3+ years takes into account only fill level/1min or other sensors as well?”
This is with all sensors functioning. But I am not convinced that temperature, humidity, and light level are all that useful in this application.
Another application for this method is car park space monitoring. This can be done using a magnetometer buried in the ground or just anchored to the floor, but it can also be done well by mounting one of these devices on the ceiling pointed downward.
We are working now to minimize the production costs of these devices. The goal is to get the price below $40 each with a 3 year life. This would make widespread use possible.
