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6

The usual approach is to trigger only one sensor at a time. In other words, time-division multiplexing, rather than frequency-division multiplexing. Otherwise, even if the sensors aren't pointing in the same general direction, coupling through the structure of the robot itself can create unnecessary interference. Just to put some numbers with that: ...


3

The transducers exist, but the ranging modules do not (for the hobbiest range at least). Selection amongst ranging modules is very low. The selection is pretty much limited to ~40kHz for broad-beam long range detection and ~235kHz for narrow beam short range detection. That's it. Frequency determines range and cone angle so you will end up at similar ...


1

I'm going to suggest an entirely different thought to consider which addresses itself to both the measurement for the purposes of on/off thresholds, as well as detecting both shorted and open cases for the LDR (broken or someone has a screwdriver shorting the contacts for some reason.) The idea works almost entirely independently from the specific LDR ...


1

I want to add a simple LED indicator that will turn ON when the LDR is broken or something Actually driving the LED indicator is the easy part, of course. Depending on the expected light output from the "LDR fault detected" LED, then a drive transistor might not be needed. For detecting that the LDR is "broken or something", you need to decide exactly what ...


1

In addition to Sphero's answer Should I consider other types of sensors (have I overlooked something critical in my sensor selection)? Use thermocouples if you need a high range 100's of Celsius to ~2000C and an accuracy of 1C, also use thermocouples for cost. Use RTD's if you need a range of 100's of Celsius, but they are most costly Use thermistors ...


1

A thermocouple is probably the best available sensor for that set of requirements but it requires careful design of the cold junctions and associated CJC sensor and thermal EMFs. No guard rings are required, thermocouples are very low impedance sources. If you can electrical connect the junction to the mass being controlled you will get faster response but ...


1

If the machine has a brushed or universal motor, you can use a triac dimmer to control its speed. However, triac dimmers are annoying to control. They fire on each mains cycle, ie every 10ms on 50Hz mains which inserts a large phase lag in the control loop. Also the input-output curve is very nonlinear. If you want to control needle position you will need ...


1

I like Python, and I use it in my own projects. I wouldn't depend on a Python loop that reads an ADC value through who knows how many layers of libraries and operating system drivers to deliver anything like a consistent sampling rate, let alone a fast rate. If you check the adafruit_ads1x15 github repository, you'll find a "fast read" example. That ...


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You are using the wrong address. 0x44 in 7-bit notation is used in datasheet, so in 8-bit notation used by STM32 it should be 0x88.


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A different approach would be to use an accelerometer to detect when the backpack is moving around, and assume that means that someone is wearing it. More of less clever algorithms could be implemented to detect if the person stands stills or is walking with the backpack. Bonus: This will inevitably be much more robust and less error prone over time as ...


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I see this is an old question, but I recently took apart an Avago optical encoder from an HP printer and can provide a photo of what is connected to the four pins mentioned in the question: My first guess is that [...] the bottom is a light sensor of some kind." From the Avago AEDS-962x datasheet, here is the description: As seen in Figure 1 ["AEDS-...


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A small quantity of warm but not boiling water will often trigger a PIR (safety in mind) or on a cold day just tap water - just throw it into the air near the sensor. Alternatively a few drops of cold water from a fridge or well will trigger on a warm day. Alternatively a well trained cat can help.


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