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Schematic diagram - first drafts
07/05/2018 at 16:42 • 0 commentsI chose ultrasonic transmitter MA40S4S and receiver MA40S4R. In the German data sheet there are many application notes with many examples of schematics. I did not find these documents in English though.
The following diagrams were created with KiCad/Eeschema based on the data sheet.
My plan is to build sub-modules that transmit and receive. Both use the same interface, which will also be used by a measurement-device. For this device all I have so far is a vague concept which I will refine in a future post:
- maybe a box with several interfaces (minimum of four) for connecting sub-modules, which
- output the 'burst*
- analogue input from three sensors
- ADC for said analogue inputs. maybe a 1 bit ADC (aka schmitt trigger)
- inside some kind of digital signal processor. may even be a small 8 bit µC
- output of scanned image. maybe a display or connector for a computer which runs 'display software'For now I will focus on creating some sub-modules and test them with an oscilloscope.
Ideally this will allow me to test my concept (in 2D for I only own a two channel oscilloscope right now).
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Theory of operation pt. 2
06/27/2018 at 16:53 • 0 commentsIn the previously post I described an simplified version of the scanning array with only two sensors.
This is, what the signals would look like if there was a single object.
Well, what's next? With these time-discrete readings of ultrasonic amplitude we can do something simillar to a time-discrete convolution to create a 2D image.
The white dot marks the object. In this simulation there is only one object, if there were more than one, artefacts will appear.To eliminate the artefacts, a threshold is applied.
%input data simulation: clear size = 10; f=ones(1,size); g=ones(1,size); style='rx'; f(2)=3; f(5)=4; g(4)=3; g(6)=4; threshold = 4; %plot input data subplot(2,1,1) stem(f,style) subplot(2,1,2) stem(g,style) %create heatmap z = zeros(size, size); for r = 1:size for c = 1:size z(r,c) = f(r)*g(c)-threshold; end end z(z<0)=0; %plot heatmap fig = figure; colormap('ocean'); imagesc(z); %create plot colorbar; %intensity bar
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Theory of operation
06/26/2018 at 21:46 • 0 commentsThis is an overview of the main function.
The main part is a digital signal processor, which creates the ultrasonic burst. The Signal is send out by the transmitter, reflected by an object and received by the sensor array.
I will focus on 2D scanning at first. Therefore the sensor array only consists of two sensors, aligned in a row with the transmitter. This also simplifies the required calculations for object detection.
In this first prototype sensor 1 and 2 are 160mm apart, the transmitter is located in the middle between the sensors. -
First note on this project
06/26/2018 at 16:46 • 0 commentsCredits for the background image go to LiDAR ParaView which is released under Creative Commons Attribution License 3.0, until I am able to provide my own images.
The picture is an example of the result which I try to create with this 3D scanner.