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We need a BLE based safety leash between a driver and a fuel nozzle, plus a LoRa link back to the truck.
-Driver wears a rugged BLE badge that simply broadcasts a BLE ID.
-Nozzle side BLE + LoRa end node (us915LoRa) that scans the badge, decides if the driver is ‘near’ the nozzle, and sends a short ‘flow-allow / stop fuel’ LoRa packet.
-Truck side LoRa receiver with a normally open safety relay that drops when it stops seeing ‘flow allow’ from the nozzle unit.
Looking for suggestions for a BLE tag/badge and BLE-plus-LoRa node (us915) that can be used this way, and can someone support or recommend a configuration for this kind of safety type application?
As I read through you’re application description, a few thoughts/questions come to mind:
Driver wears a rugged BLE badge that simply broadcasts a BLE ID.
For a safety critical application such as what you’re describing, this is a very insecure communication protocol. It’s fine for a proof-of-concept, but do realize that it leaves the system vulnerable to replay/spoofing attacks.
Nozzle side BLE + LoRa end node (us915LoRa) that scans the badge, decides if the driver is ‘near’ the nozzle
How exactly does the nozzle decide if the driver is ‘near’ the nozzle? RSSI? If by near in this scenario you mean “in the general vicinity”, then this might be just fine. But if by near you mean “the driver is standing next to the nozzle and attending it carefully”, then this probably isn’t the best solution. 1) Bluetooth isn’t capable of precise ranging measurements and 2) there’s no way to tell if the driver is actually wearing the badge or if they simply laid it down next to the nozzle somewhere and wandered off. You may want to consider something like a UWB-based solution and also incorporating a motion sensor (e.g., accelerometer) into the badge.
and sends a short ‘flow-allow / stop fuel’ LoRa packet
Aside from the same security concern I raised earlier, I’m not sure why LoRa is the technology of choice here. LoRa is best suited for applications requiring extremely low-power consumption but also very long-range. Is the nozzle really going to find itself so far away from the truck that a Bluetooth connection becomes unreliable? If so, fine. But if not, why make the solution more complicated than it has to be by incorporating multiple wireless technologies?
Regarding your core ask:
Looking for suggestions for a BLE tag/badge
Really, any BLE module/chipset could be employed for the purpose you’ve described. It’s just a matter of prototyping a solution on your preferred development platform and then creating a custom badge design using the target RF solution for further testing/development. If what you’re looking for, though, is something already in badge-form, then the best option I’ve found is this offering from Seeed. Very much overkill for what you’ve described, but it could serve as a good starting point. Note that it includes a BLE module (the core of which is Nordic’s nRF52840) and an accelerometer/gyroscope sensor from STMicroelectronics.
and BLE-plus-LoRa node (us915) that can be used this way
Sounds like what you’re asking for is an RF module that includes both BLE and LoRa communication capabilities. These exist, though they aren’t extremely common. A good example would be this LPWAN module from RAK. Chipset-wise, it features another nRF52840 for the BLE portion as well as Semtech’s SX1262 for the LoRa portion.
Thank you very much for your thoughtful response! I am completely new at this and learning as I go with a defined end goal in mind, so your comments, questions, and feedback are greatly appreciated. My goal is to create a system that is rugged, simple to use, low power use requirements, and doesn’t inhibit the person using it.
I researched many different forms of communication and determined (through AI) that BLE would be better suited than UWB due to power requirements. It appears that BLE devices could go very long periods of time (weeks/months) without new batteries, whereas UWB would require frequent charging or battery swaps. If this isn’t the case, I’d love to know. Again, I don’t know what I’m doing, just trying my best with large language models and research. My understanding was that BLE could be used for very approximate distancing, maybe to within 10’ or so, which isn’t ideal, but is better than nothing. It also sounded as if it could potentially be “tuned” to narrow down the distance?
Regarding the LoRa useage, the fuel trucks often carry 150’ or more of hose and often the operator will need to drag the nozzle end of the hose around obstacles, buildings, etc, so I wanted something that wouldn’t lose contact with the truck.
For context, the reason I am trying to develop this system is because I work for a large fuel company where we’ve had some bad spills due to drivers leaving a nozzle unattended under flow to go sit in the fuel truck and warm up. This is a people problem, not a technology problem, but it keeps happening (and is expensive/unacceptable), so I’ve been challenged to come up with a solution to prevent the driver from leaving the nozzle under flow. If I get a proof of concept, the next challenge will be how to make sure the driver doesn’t leave the badge/bracelet/fob next to the nozzle while they go sit in the warm truck….
Again, thank you for your help and I look forward to researching the options you provided. Please feel free to leave a reply at any time.
You said this a couple of times so I’d be remiss if I didn’t point out that we do maintain a list of design service providers for those who need to realize a solution which is out of their realm of expertise. That being said, I do have some more thoughts on your application.
Yes, UWB in general tends to consume more power than BLE during a ranging/communication session. But the difference depends on many factors like what modules you are using and how you set the RF parameters. Looking at the datasheet for the DWM3001C from Qorvo as an example, we see that the TX current consumption (Figure 2) is actually less than that of the RAK module I mentioned earlier (Figure 1).
What really matters is how often you use the radios. For low-power applications, you want all the chips on your board to spend as much time in low-power sleep/standby modes as possible. Considering your application, I imagine that the mobile tag kept by the driver doesn’t have to constantly be ranging, correct? Perhaps determining distance from the nozzle could occur every 15, 30, or 60 seconds? And even then, this only has to be occurring during the actual fueling process. That’s a lot of time the module could spend in sleep mode allegedly consuming only 850 nA according to the datasheet.
Ten feet might be achievable, but I imagine it would still be quite error-prone as there are so many environmental factors out of your control. I’ve never come across any methods of “tuning” as you mentioned, other than rudimentary average filtering…
I’m not saying this approach wouldn’t work for your application, though. I really depends what you’re requirments are. The BLE RSSI approach could give you an idea of near vs far, but there’s a VERY fuzzy line between those two. The UWB approach could provide much more precise ranging at the expence of added complexity.
That sounds reasonable. Hard to say what the best solution is without better understanding what the worst-case scenario will be. A sub-GHz solution like LoRa would indeed be likely to provide a more robust connection in general thanks to it’s greater reach and penetrating capability. However, managing multiple wireless solutions in a single application can quickly get quite complicated (and expensive).
Just a thought, but have you considered which requirement is most important as it relates to this issue?
The driver is standing next to and attending the nozzle during fueling
or
The driver is not sitting inside the truck during fueling
Given the constraints you have to work with, I would say Requirement 2 is a much simpler one to focus on solving. If you can ensure the driver is not warming up inside the truck during fueling (using any number of sensors inside the cabin), then what else are they going to do other than watch the nozzle? I don’t know the answer to that question and I’m sure some accidents would still happen. But I imagine there wouldn’t be nearly as many and not at the same level of severity as you’re currently experiencing.
