# Tag Info

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Another popular rotary sensor is the ratiometric Hall effect sensor. Use a device like the A1324. It's a 3-pin device which gives an analog voltage proportional to the magnetic field strength. For a magnet, you have two options: A diametrically polarised ring magnet mounted on the steering column. The sensor should sit at the circumference of the magnet, ...

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I would think you should be able to. I've used magnets and reed switches in a similar application for a speed sensor which uses the turns to calculate speed much like an encoder and it worked perfectly. The hall sensor should behave in a similar way.

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Sometimes they are called linear halls. A company called Eltrol used to make drives for these. I used them in the past in combination with Anorad Linear motors. Nowadays they are still available from PeakServo. The drives drive the linear (or sine) hall and receive the two halll signal (which are 120 degrees apart). http://www.peakservo.com/series-45-...

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Probably a simple and cost-effective solution would be to use a flex sensor. Essentially you can determine the amount of flex subjected on the sensor using resistance, much like a potentiometer.

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A potentiometer linked to the output gear of your motor controlling the joint is the simplest position sensor. This is typically what is done inside cheap servomotors. You will get an analog signal relative to the position of the output gear. Position can be found using the relation $$\theta = \theta_0 + \frac{V_{out}}{V_{max}}$$ With $V_{max}$ the ...

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Potentiometers are great for this kind of thing. Its what servos use to move to specific angles. They offer a linear resistance change that could be used to change an analog voltage that you measure, then angles map directly to that voltage.

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To measure position more accurately you need to use all three. They are used for choosing which motor phase to energise, which is called commutation. Searching for "6 step commutation" will give you lots of diagrams and info on how to estimate position this way.

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Thanks to @RobReus, who pointed me to a Youtube video describing my issue I was able to fix it. The issue was in fact my Raspberry Pi not being able to keep up with the amount of interrupts a second and losing some of the events. The solution I came up with is to attach hall sensor to my Arduino Nano which is connected to Rpi via serial port. Interrupts are ...

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Since the encoder with that motor is an incremental encoder, you would have to keep track of the motor position constantly. If you really want to go to a home position, you'll need another sensor, like a limit switch, to tell you when you've gotten to home. There are also physical problems such as acceleration and deceleration which makes stopping ...

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Are you running a PID loop to control the motor? Without a PID loop, the motor is going to be highly dependent on load and will likely stop differently every time. Also, since the sensor is relative position only, you will need a way to home the motor to be able to know absolute position. If you need accurate absolute position, you could use a hall ...

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This question might be better suited to the Physics StackExchange, but the back-of-the-envelope calculation goes like this: The Earth's magnetic field is 31.869 µT, and a refrigerator magnet is 5000µT. So the refrigerator magnet will very readily affect the magnetometer (not usually called a hall-effect sensor) on a smartphone. However, you will run ...

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I've figured out the problem a while ago. It turns out to be a power supply problem. I'm using a computer power supply (Antec HCG 850M) with the under voltage & over current protections removed, so it doesn't trip. There was also another huge problem I didn't mention. The motor was randomly stopping and starting several times a second. Then I saw that ...

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