I want to rebuilt my High-Speed Ebike after it went down.
I tried a Chinese out-of-the-box controller ($40) but it only rotates the 36DC 400W motor at 3 speeds.
Since I want to enhance the bike (GPS, RasPi) I might better intergrate the whole thing, so now I'm thinking of a bare PCB to regulate the speed of the 3 phase motor. Regulation is done by an analogue pot with knob. Could be this one
I'm looking for a way to replace the knob with a electronic version, that takes its input from the speedsensor. This is magnetic switch (Hall?), normal open.
So I'm looking for something that builds up a voltage between 1.8 and 4.9v, depending on the frequency of pulses from the sensor.
I hope this makes sense and somebody is able to get me on track for a solution.
TIA!
It works the other way around. There's no voltage to be 'build up', rather there should be a max voltage (5V) availlable that's dimmed to lower levels by a 10K digital potentiometer. The lever is controlled by a SPI-signal that's generated by the Pi.
Microchip Technology has quite a bunch of them: https://www.microchip.com/paramChartSearch/chart.aspx?branchID=11026
Still have to work this out on a board, though.
Related
I got the problem of the pedestrian library. I would like to use the pedestrian library to simulate the behavior of the vehicle, therefore, I would like to set the comfortable speed of the agent to be, say 70km/h. However, there is an error saying the speed has to be within [0mps, 10mps]. Is there any way to set whatever speed I want?
Thank you,
Jiannan
First why don't you use the road traffic library? But you must have your reasons.
You can't change the maximum speed value, but what you can do, which is not a very elegant solution, but a solution nonetheless, is to change the time scale of your model. There is no direct option for that, so you basically have to create your own clock that runs your way.
So for instance, if you want your car to move at 20mps, you choose 10 mps as the comfortable speed and you have the transformation customTime(time())=0.5*time(), where custom time is your own function.
So every time 1 second passes in the simulation, in your custom clock only 0.5 seconds will pass... You just have to take care of the statistics you are collecting so they fit your time scale.
Also, you will have to change everything according to your clock in your model, because Anylogic will continue showing you things in normal seconds.
Hope that helps :)
I have a project that consisted of transmitting data wirelessly from 15 tractors to a station, the maximum distance between tractor and station is 13 miles. I used a raspberry pi 3 to collect data from tractors. with some research I found that there is no wifi or GSM coverage so the only solution is to use RF communication using VHF. so is that possible with raspberry pi or I must add a modem? if yes, what is the criterion for choosing a modem? and please if you have any other information tell me?
and thank you for your time.
I had a similar issue but possibly a little more complex. I needed to cover a maximum distance of 22 kilometres and I wanted to monitor over 100 resources ranging from breeding stock to fences and gates etc. I too had no GSM access plus no direct line of sight access as the area is hilly and the breeders like the deep valleys. The solution I used was to make my own radio network using cheap radio repeaters. Everything was battery operated and was driven by the receivers powering up the transmitters. This means that the units consume only 40 micro amps on standby and when the transmitters transmit, in my case they consume around 100 to 200 milliamps.
In the house I have a little program that transmits a poll to the receivers every so often and waits for the units to reply. This gives me a big advantage because I can, via the repeater trail (as each repeater, the signal goes through, adds its code to the returning message) actually determine were my stock are.
Now for the big issue, how long do the batteries last? Well each unit has a 18650 battery. For the fence and gate controls this is charged by a small 5 volt solar panel and after 2 years running time I have not changed any of them. For the cattle units the length of time between charges depends solely on how often you poll the units (note each unit has its own code) with one exception (a bull who wants to roam and is a real escape artist) I only poll them once or twice a day and I swap the battery every two weeks.
The frequency I use is 433Mhz and the radio transmitters and receivers are very cheap ( less then 10 cents a pair if you by them in Australia) with a very small Attiny (I think) arduino per unit (around 30 cents each) and a length on wire (34.6cm long as an aerial) for the cattle and 69.2cm for the repeaters. Note these calculations are based on the frequency used i.e. 433Mhz.
As I had to install lots of the repeaters I contacted an organisation in China (sorry they no longer exist) and they created a tiny waterproof and rugged capsule that contained everything, while also improving on the design (range wise while reducing power) at a cost of $220 for 100 units not including batterys. I bought one lot as a test and now between myself and my neighbours we bought another 2000 units for only $2750.
In my case this was paid for in less then three months when during calving season I knew exactly were they were calving and was on site to assist. The first time I used it we saved a mother who was having a real issue.
To end this long message I am not an expert but I had an idea and hired people who were and the repeater approach certainly works over long distances and large areas (42 square kilometres).
Following on from the comments above, I'm not sure where you are located but spectrum around the 400mhz range is licensed in many countries so it would be worth checking exactly what you can use.
If this is your target then this is UHF rather than VHF so if you search for 'Raspberry PI UHF shield' or 'Raspberry PI UHF module' you will find some examples of cheap hardware you can add to your raspberry pi to support communication over these frequencies. Most of the results should include some software examples also.
There are also articles on using the pins on the PI to transmit directly by modulating the voltage them - this is almost certainly going to interfere with other communications so I doubt it would meet your needs.
I'm making a simple electric circuit simulator. It will (at least initially) only feature batteries, wires and resistors in series and parallel. However, I'm at a loss how best to simulate said circuit in a good way.
Specifically, I will have batteries and resistors with two contact points each, and wires that go between two contact points. I assume that each component will have a field for its resistance, the current through it and the voltage across it (current and voltage will, of course, be signed). Each component is given a resistance, and the batteries are given a voltage. The goal of the simulation is to assign correct values to all the other fields in real time as the player connects and disconnects components and wires.
These are the requirements:
It must be correct, including Ohm's and Kirchhoff's laws (I'm modeling real world circuits, and there is little point if the model does something completely different)
It must be numerically stable (we can't have uncontrolled oscillations or something just because two neighbouring resistors can't make up their minds together)
It should stabilize relatively quickly for, let's say, fewer than 30 components (having to wait a few seconds before the values are correct doesn't really satisfy "real time", but I really don't plan on using it for more than 10 or maybe 20 components)
The optimal formulation for me (how I envision this in my head) would be if I could assign a script to each component that took care of that component only, possibly by communicating field values with neighbouring components, and each component script works in parallel and adjusts as is needed
I only see problems here and no solutions. The biggest problem, I think, is Kirchhoff's voltage law (going around any sub-circuit, the voltage across all components, including signs, add up to 0), because that's a global law (it says somehting about a whole circuit and not just a single component / connection point). There is a mathematical reformulation saying that there exists a potential function on the points in the circuit (for instance, the voltage measured against the + pole of the battery), which is a bit more local, but I still don't see how to let a component know how much the voltage / potential drops across it.
Kirchhoff's current law (the net current flow into an intersection is 0) might also be trouble. It seems to force me to make intersections into separate objects to enforce it. I originally thought that I could just let each component have two lists (a left list and a right list) containing every other component that is connected to it at that point, but that might not make KCL easily enforcable.
I know there are circuit simulators out there, and they must have solved this exact problem somehow. I just can't find an explanation because if I try googling it, I only find the already made simulators and no explanations anywhere.
Is there a way to calculate the electricity consumed to load and render a webpage (frontend)? I was thinking of a 'test' made with phantomjs for example:
load a web page
scroll to the bottom
And measure how much electricity was needed. I can perhaps extrapolate from CPU cycle. But phantomjs is headless, rendering in real browser is certainly different. Perhaps it's impossible to do real measurements.. but with an index it may be possible to compare websites.
Do you have other suggestions?
It's pretty much impossible to measure this internally in modern processors (anything more recent than 286). By internally, I mean by counting cycles. This is because different parts of the processor consume different levels of energy per cycle depending upon the instruction.
That said, you can make your measurements. Stick a power meter between the wall and the processor. Here's a procedure:
Measure the baseline energy usage, i.e. nothing running except the OS and the browser, and the browser completely static (i.e. not doing anything). You need to make sure that everything is stead state (SS) meaning start your measurements only after several minutes of idle.
Measure the usage doing the operation you want. Again, you want to avoid any start up and stopping work, so make sure you start measuring at least 15 seconds after you start the operation. Stopping isn't an issue since the browser will execute any termination code after you finish your measurement.
Sounds simple, right? Unfortunately, because of the nature of your measurements, there are some gotchas.
Do you recall your physics classes (or EE classes) that talked about signal to noise ratios? Well, a scroll down uses very little energy, so the signal (scrolling) is well in the noise (normal background processes). This means you have to take a LOT of samples to get anything useful.
Your browser startup energy usage, or anything else that uses a decent amount of processing, is much easier to measure (better signal to noise ratio).
Also, make sure you understand the underlying electronics. For example, power is VA (voltage*amperage) where both V and A are in phase. I don't think this will be an issue since I'm pretty sure they are in phase for computers. Also, any decent power meter understands the difference.
I'm guessing you intend to do this for mobile devices. Your measurements will only be roughly the same from processor to processor. This is due to architectural differences from generation to generation, and from manufacturer to manufacturer.
Good luck.
Hi: I want to do a sound waves simulation that include wave propagation, absorbing and reflection in 3D space.
I do some searches and I found this question in stackoverflow but it talk about electromagnetic waves not sound waves.
I know i can reimplement the FDTD method for sound waves but how about the sources and does it act like the electromagnetic waves ? Is there any resources to start with ?
Thanks in advance.
Hope this can give you some inputs...
As far as i know, in EM simulations obstacles (and thus terrain) are not considered at all. With sound you have to consider reflection, diffraction, etc
there are different standards to calculate the noise originated from different sources (I'll list the europe ones, the one i know of):
traffic, NMPB (NMPB-Routes-96) is THE standard. All the noise calculations have to be done with that one (at least in my country). Results aren't very good. A "new" algorithm is SonRoad (i think it uses inverse ray-tracing)... from my tests it works great.
trains: Schall03
industries, ISO 9613
a list of all the used models in CadnaA (a professional software) so you can google them all: http://www.datakustik.com/en/products/cadnaa/modeling-and-calculation/calculation-standards/
another pro software is SoundPlan, somewhere on the web there is a free "SoundPlan-ReferenceManual.pdf" 800-pages with the mathematical description of the implemented algorithms... i haven't had any luck with google today tough
An easy way to do this is use the SoundPlan software. Multiple sound propagation methods such as ISO9613-2, CONCAWE and Nord2000 are implemented. It has basic 3D visualization with sound pressure level contours.