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Author Topic: Measuring angular movement with a rotary encoder or accelerometer?  (Read 654 times)

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Offline Malin_681Topic starter

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I am going to construct a robot hand that will follow the motions of a human hand. I need advice on which type of component or sensor that would be best to use when I am going to detect the movement of the wrist of the human hand. The sensor for the wrist must be able to detect when the wrist turns and how many angles the wrist has turned. It should also be able to tell if the wrist turned clockwise or counterclockwise.

I have considered using either an absolute rotary encoder or an accelerometer. The component is supposed to be connected to an arduino platform that will interpret the signals. Does anyone have experince using either an absoulte rotary encoder or accelerometer togehter with the ardunio platform to mesure angular movement? Or is there other components that are better to use when detecting the turning of the wrist?

Offline newInRobotics

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Re: Measuring angular movement with a rotary encoder or accelerometer?
« Reply #1 on: February 15, 2013, 12:48:28 PM »
In my opinion the simplest way around it is to use 2 potentiometers (one for flexion & extension and one for radial & ulnar deviation).

You can use two 3-axis accelerometers, but data will be very noisy and will require some clever algorithms to filter it and work out angles.
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Offline Malin_681Topic starter

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Re: Measuring angular movement with a rotary encoder or accelerometer?
« Reply #2 on: February 17, 2013, 11:43:11 AM »
okay, thanks for the answer. :)
the thing is, that the only movement that i would like to detect is when the wrist rotates, in other words, i only want to measure the rotation of the wrist in one axis. so the sensor i use does only need to mesure the rotational angle in one axis. so is it enough with only one acceleromter if i just want to measure one axis of rotation?

Offline newInRobotics

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Re: Measuring angular movement with a rotary encoder or accelerometer?
« Reply #3 on: February 17, 2013, 02:54:54 PM »
I am not sure what exactly You want to measure, because wrist does not rotate, Your forearm rotates (it's called supination and pronation). To measure that You can still use potentiometer, or if You want to be fancy - gyroscope & accelerometer :)
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Offline jwatte

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Re: Measuring angular movement with a rotary encoder or accelerometer?
« Reply #4 on: February 17, 2013, 11:24:13 PM »
Two accelerometers and magnetometers -- one on the palm, and one on the forearm -- would let you calculate relative orientations, which would in turn let you calculate how much the wrist is bent. The magnetometers may actually be best for this, as they don't see additional forces because of the movement itself.

Another option is to buy something that already does what you want. There are various kinds of "gamer gloves" around that may already suit your needs.

 


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