Here is a little background on what I am trying to accomplish:
I work at a power plant. I have been tasked with building a project to display wind speed. We have truck tippers that lift tractor-trailer trucks up on a really steep incline in order for them to dump the wood chips out the back. They are not supposed to use the tipper if the wind speed gets above a certain limit. They want me to install an anemometer to measure the wind speed and to display it using custom fabricated, seven segment digits. These digits need to be 2 feet tall in order for our bulldozer operators to see it from up to 300 feet away in broad-daylight. They will then shut down the tippers and prevent the truck drivers from using them if the wind speed is too high. I’m thinking I will also need to build a small shed above the displays to shade it from the sun a little so that the digits cab be seen better.
I would like to use an Arduino for this project. This will be my first time using an Arduino. I have worked with other micro-controllers before and have a beginners level knowledge of using code.
I will be using an Anemometer from Adafruit to measure the wind speed. The output is 0.4 to 2.0 Volts.
I will be custom building the 2 foot tall seven segment displays.
Questions:
Which Arduino would be the best choice for this project? (Looking at using the UNO).
Should I use the outputs on the Arduino to activate transistors that drive each segment of the displays separately; forming the numbers by activating the appropriate segments or, is there a simpler method that someone can share?
Any help, ideas and/or guidance on this project would be much appreciated.
Any Arduino can read a voltage (e.g. from a wind sensor) and send control signals to a display.
The answer depends on the specifics of the display. Post a link to the product page, the data sheet, or complete information on how the display is controlled. A circuit diagram would be very helpful.
Nice project. Just thinking out aloud, what about flip 7-digit displays? You don't have to update the speed more than once every 10 seconds or so and this display is visible from a great distance under day light. Never used one myself though:
Digits? Your dozer drivers want to read digits? If I'm the one driving a dozer, I don't want to have to remember what wind speed is acceptable or isn't. Just put up a single big red light that says "stop". Buy an old traffic light, so it looks more legit. (Of course then your guys will ask you to make the yellow come on when the wind speed is close to the limit.)
The outdoor part of the anemometer is the most critical. It needs to be weather-proof and vandal-proof. (If you're driving a dozer and this is stopping you from doing your job, you won't be to careful about not crushing it.) Not to mention, it needs calibration.
Peet Bros. make some good, simple anemometers. You will be shocked at the price when you look at how simple they are, but honestly, simple is good. Building your own and calibrating it in a wind tunnel is beyond the skills of most people I know.
Using digits has the advantage that an incresing wind can be observed and work planned according to that.
Having both education and experience from aero dynamics I point out the importance of placing the anemometer in a place where buildings etc. will not trick the readings.
When life is at stake I beleive any professional driver will follow given orders, but of course, adding a large red light adds clearance.
Best scenario I can think of use optocoupler to drive the mosfets and use arduino to drive the optocoupler. In this way there will be no durability problem. This is very very safe setup due to importance of the problem. TLP521 can do the trick for you as optocoupler. And select a proper mosfet preferable N channel sourcing current type that fits your voltage range and current limits. Thats it. Have a nice day.
MorganS:
.... Not to mention, it needs calibration.
well, the way hobbyists do things, you set your unit up and data log.
then you use it until it goes past where you want
then cut back to about 80% of that.
install the unit,
data log.
dump the trucks as normal
once one or two flip over, use that as max,
set yor red light to that 80% level and you're good to go!
I am less than enthusiastic about digits as well.
a 10 bar LED display is not hard to light up.
lower 4 green next 3 yellow, then the next 3 red.
however the OP said the loader drivers will close the tipper. not the truck drivers.
that means the loader operators would be trained in the problems and procedures.
I would put up 4 or more anemometers with ESP8266 or NANO and an RF output.
signal the speed of each to the main unit at the LED display.
common LED's with clear lense and narrow beam will appear to be very bright to a driver in the center of that beam.
maybe even blink the RED once it gets into the un-safe zone.
My suggestion is to get a cheap Anemometer, a mini and an RF module
get a cell phone battery charger for the unit.
since the mini does not have the USB link, it will not burn as much power.
mount this on a pole, on the lift at the section that is highest, on a tree, on a building, etc, take and log readings to get a picture of the flow around the plant.
Also the air speed at the top might be much higher than at the ground level.
A hard solution would be gates of some kind prohibiting further work….
Go on with Your idea! The intention is godd!
Once forklift drivers complained about false alarms from a safety system. The chief said: Don't trigger the alarms unless You want to get fired… Management.....
The truck tippers can't be seen from the control room at our plant. They are at a remote location on the other side of a huge pile of wood chips. The only people that see them while they are in operation are our bulldozer operators. The truck drivers do not stay on the truck while it is on the tipper. They back the truck onto the tipper then they go to a control panel booth and activate the tipper. The tipper raises the truck up to about a 60° angle so the wood chips dump out. There are no buildings or trees near there. The anemometer will be mounted on a tall pole near the tipper control booth.
Our bulldozer operators do not load the trucks. They push the wood chips over to a very long conveyor that carries the wood to the fuel bins at the plant. Our bulldozer operators decide when to stop the tippers because of wind speed but, they do not have a way to know the exact wind speed. The safety rules state that the tippers can't be used if the wind speed is above 32 MPH. My boss wants numbers, so I got to give him numbers, even though I suggested the idea of the traffic light. He thinks it will be cool to see the actual wind speed. The bulldozer operators have a remote kill switch for the tippers in the cab of the bulldozer. Tried to convince the boss to let the Arduino itself stop the operation of the tippers but, he wants the bulldozer operators to make the decision.
I will look into the idea of the flip digits (never saw them before) Thanks liuzengqiang.
I will not be building an anemometer. I am ordering it from adafruit.com ($44)
I will post pictures and some schematic ideas as soon as I can to help everyone understand my project.
Is there a way to post a video? Would like to show the tippers in operation.
Well, with all respect for Adafruit, they're targeting the hobby market. You don't. If that anemometer fails and an accident happens, you did it. You find the exact same products Adafruit sells (yes, the very same) for 1/10th the price on Taobao and Aliexpress, sometimes even less. It's fine for hobby work, but I wouldn't want it in any professional environment, and even less so when it's a safety device. If your power plant doesn't even have the budget to buy a proper anemometer, that's a big problem. I'm quite sure your hourly salary is more than such a cheap anemometer from Adafruit.
If you get an anemometer from a reputable anemometer manufacturer, recommended by the weather services or aviation industry, you at least can say you did your homework and went for something that's proven and reliable, and that will be measuring the wind for years to come without any maintenance. Preferably with a digital output as it is so much easier to read out.
For the display, numbers are good. A traffic light as well. What's stopping you to implement both? I fully understand your boss wants to see numbers: that tell the story. Is it above the limit? Red light - but how much above the limit? Is it orange, how close are we to either the red or green side?
Such big displays I expect to have their own power supply, and a simple digital input where it takes the data from an MCU, so that's another thing you shouldn't have to worry about. Plug it into a power socket, wire up your MCU, and off you go. Such displays won't come cheap of course. At least a commercial one comes with warranty on waterproofing and so, after all your job is to measure and display wind speed, not to develop a waterproof LED display. Do your research on commercially available displays first, then start worrying about controlling them!
Some professional quality air sensor/weather station solutions:
I'm not associated with this company. I've used their sensors in the past with no complaints. I do a lot of data logging. I'd start with their sonic anemometer since there is no moving part that is prone to failure.
This company used to be a US company "Decagon" until they merged with a German company.
I do things in stages I use cheap stuff wants to make sure the concept can actually work then I actually did I replace the pieces with high-quality pieces to implement in the field.
The low-cost anemometer and displays can be proof of concept.
Install that verify that's exactly what's needed and wanted.
Then get the quality stuff for a permanent installation that will last year's
There is no danger to personnel. Only to equipment. Which of course is also bad. They truck drivers are located far enough away and have to hold two buttons in(one for each hand) for the entire three minute process. That way, if they leave the booth, the tipper stops. The drivers do not stay on the truck.
The boss has given me a budget of a measly $700 and expects me to pull this off. Commercial signs with digits that are large enough to see from up to 300 feet away have proven to be extremely expensive. Costing far more than this pittance of a budget allows. Although,.....it would be kind of fun to see if I can custom fabricate my own two foot tall digits, that also is turning out to be very expensive. Hopefully we can brainstorm an idea that would work and come in within the budget.
I am looking for a higher quality anemometer per your advice. How reliable is the Arduino? I know that it is also a considered a hobby item. Maybe I will have to consider something else. Oh well, I doubt I will be able to meet that budget anyway.....
You could create your 2' digits from led strip. Cut the strips to make each segment, then wire each digit up to a tpic6b595 chip to drive it. Single colour led strips generally need 12V power, but the tpic chips can handle that. I am working on a clock with 200mm (~8") digits using the is technique at the moment. Each of the chip's 8 outputs can sink 150mA which should be enough for a 1' segment, assuming a strip with 60 LEDs per metre.
Here is a test print that I made with my 3D printer of one of the segments for a seven segment display. I am using an L.E.D. strip from superbrightleds.com. For now I hooked up a battery pack to check the brightness.
Looks neat. Hope your boss is paying you for that 3D design and printing work, and that your time (salary) is not part of your budget.
Powering those things is going to be another challenge. You've got 18x4x0.02 = 1.44A per segment - if you have 2 1/2 digits that's 16 total segments, 23A. Get a 30-40A 12V power supply for that.
Every segment will need its own driver - a normal logic level MOSFET will do. Probably the easiest approach to this is to take a regular 7-segment display driver IC, and where the LEDs would go on the outputs you connect the MOSFET's gate. Then you have the ease of programming of a small sized display.
Another approach for this would be two shift registers (8 segments each) for the output.
