Smart city sensors


(Osbex) #1

Hi,
Scouting sensors for smart city solution (waste bins, air quality measurements, water quality/levels/leakage etc.). Most vendors have the following issues on their web sites:

  1. Too much basic information.
  2. They focus too much on add-on features and their platform which normally is of no interest if you just look for sensors.
  3. Too many sensor versions.

I’m turning to this forum to see if someone has tested any of the above mentioned sensor types and can share some best practice advice?

Thanks in advance!

Cheers,
Oscar


#2

maybe you could start a list what you found and other users can add info ? :sunglasses:


(Osbex) #3

The problem is that a single vendor can have hundreds of sensors in their portolio. If I create a list right now it will be infinitely long and useless as I haven’t yet started to test anything myself. Will be able to add information myself during next year, but was hoping someone here could shorten the ramp-up time by knowledge sharing from failed projects. :wink:


#4

I understand, but in my experience this type of questions don’t work very well on this forum, you have to show some ‘work’ yourself.
And your question is not very specific, as you said their could be hundreds of sensors that fit your description ‘waste bins, air quality measurements, water quality/levels/leakage etc.’

be more specific… tell something about your use case for example.


(Osbex) #5

Gotcha. Use cases:

  1. Smart bins use case: The idea is to measure the filling levels so that you don’t empty bins with no trash, so that you can route your cars in the most optimal way and so that no bin is overfilled. I have seen very good use cases/results here from both regular public trash bins and recycling bins (glass, paper etc.). Savings typically range from 50 to 80% in time/fuel/dollars. I’m looking for a sensor that can measure filling level, typically ultrasonically, and report it over LoRaWAN. There are many such sensors around. Interested to hear if someone has tested any.

  2. Similarly, there are quite clear use cases to measure water in various ways. Filling levels and water quality is often measured manually to a quite high cost. Leakage is often not measured at all. Some municipalities I’ve talked to say they sometimes register that the water consumption is 50% higher than what they charge for. A pipe might be broken somewhere. Again, looking for references here. Someone who has tested sensors and can tell if there is a good one that does what it should.

When I have tested something myself I will share my findings here.


#6

anything on climate … certification… life battery … remote updates … networks … region


#7

Water quality is a wide topic, you need to specify what you need to measure: Turbidity, colour, nitrates, phosphates, ammonia, iron, aluminium, pH, conductivity, ORP, pollutants etc. A lot of these are not simple sensors and will be expensive units requiring chemical reagents. This is based on my industry experience.

Level, flow and leaks are fairly straightforward and readily available now.

If you’ve got a specific application then there are organisations that can develop sensors but this will require a minimum order of several hundred or thousand to make it cost effective.

Andrew


(Osbex) #8

Well, that’s exactly the kind of lists I have gone through. Then I speak to people who have tested sensors and they say the quality is like night and day depending on what you get. So if someone has tested something that works or doesn’t work, it would be nice if they shared findings.


(Osbex) #9

What I’m after is mainly level, flow and leaks. It’s straight forward, but it’s a djungle of sensors out there and I would like to know if someone has tested something that works.


#10

I create my own for a living. Was one of the first to produce a lora river level sensor and now it has been copied by others.

Andrew


(Osbex) #11

Do you have link to that project you could share?


#12

Its at https://flood.network/


(Onehorse) #13

Material level, like for a trash bin, can be measured with a simple time-of-flight proximity sensor like the VL53L0X, which uses I2C for connection, measures distance to the nearest surface independent of surface reflectivity and has a range of 0 - 2 meters. Here is a breakout for such a sensor:

adding such a sensor to a LoRa enabled dev board like this:

could be a reasonable solution to at least the bin level problem.


(Brulath) #14

Using ultrasonic sensors to measure fluid level is one of the suggested uses by the sensor manufacturers, so it’s pretty common. I’m curious to know if you’ve had any issues so far with condensation, spiders making homes, finding adequately calm water with something above it to mount on, keeping track of sensor locations, etc.

Condensation can be countered by purchasing the more expensive sensors which can self-clean, but that comes with increased energy requirements (~68 mA avg current, must be on for ~40 sec at a time). This might mean you need a larger battery, depending upon measurement frequency, or a small solar panel and a rechargeable battery (which is more expensive and would require mounting stuff on top of whatever you mount the sensor under).

Spiders seem happy to spin their webs around ultrasonic sensors; the web doesn’t generally affect the reading, but anything caught in it and suspended under the sensor will. That means a maintenance visit to correct the issue, which is sub-optimal for sensors suspended half-way across a river.

An alternative method of measuring the depth of water is a pressure transducer, but those are relatively pricey, require installation in the river beneath low tide, and have other requirements (such as filtered access to air for pressure comparisons). The ones I’ve used also state that they require re-calibration at the factory yearly, though that isn’t going to happen.

Somewhat related, the problem with using ultrasonic sensors for bin level measurement isn’t that hooking up a sensor is difficult, it’s protecting it against damage/theft. It needs to be slim enough to have the greatest range above the bin, avoid damage when emptying the bin, be difficult to remove from the bin, and be semi-resistant to intentional damage (chewing gum, someone with a lighter trying to burn it, etc.) You can encase it in metal, but that makes it larger and more difficult to get decent radio range.

I’m quite interested in finding a way to solve these issues in a very low-maintenance way, to allow for mass installation of sensors. The problems seem quite easy to solve at face value, but it doesn’t appear to be quite so easy.


#15

I’ve also developed LoRaWAN Nodes using pressure depth sensors. As you say, these are expensive and the one I’ve used had a 4-20mA current loop interface. As a proof of concept it worked well.

For bin level sensors, the time of flight sensors are a more compact solution and the one I have has been working very well for most of the year now.

Andrew


(Steve James) #17

Hi osbex. I agree, it can be a little bit chicken and egg.

We want to go to our ‘business units’ and show them potential as well as ask them what their main issues are.

We are piloting the Flood Network sensors and would be happy to discuss.

We’d be happy to invest/purchase solutions but could do with a balance between prototyping and solutions with some sort of track record.

Thanks


(Osbex) #18

If you have something I could look at, please send PM with your mail and I’ll contact you.


(Osbex) #19

Steve, I didn’t get whether you’re a manufacturer or if you’re also looking for sensors. Please send a PM if you have something to offer and I will take a look at it.


(Osbex) #20

Do you have that one productified? :wink:


(Onehorse) #21

I am assuming you are asking about the VL53L0X?

There is no off-the-shelf product, but prototyping elements are all in place and if there were a need and the VL53L0X solved the bin-level problem this could be turned into a product in short order.

Please email me at tleracorp@gmail.com if you want to discuss further.