I need to measure a moving double pendulum's velocity and acceleration in reference to its resting position. It is a fairly large pendulum with a trajectory with a radius of about a metre and so I was unsure what to look for.
Most of the accelerometer information I have found has linked them to the applications of smallscale scenarios like the tilting of a smartphone, which I worry may mean that the accelerometer is of the wrong scale for the outcome I need.
Could anyone give me some clarity on what exactly I should look out for when searching for the accelerometer - or gyroscope - I desire?
A consumer grade accelerometer can be used to measure the acceleration, but in practice, not the speed. Most will measure several g's which should be fine, unless the pendulum is moving at high speed.
The problem will most likely be how to get the data from the sensor without using wires that tangle or break.
What would a high speed be in this scenario? The pendulum will always rely on gravity and the subsequent potential energy to rotate, do you think this may ever be too much?
Also in regards to the tangling, a slip ring should do the trick wouldn't you think?
Probably not. You need several of them, power, ground and communication. Communications will be unreliable.
Most consumer grade accelerometers register 6, 8 or more g and your pendulum bob would have to be moving at fairly high speeds to generate such forces.
For an object rotating with angular velocity w (radians/sec) about a point with radius R, the inward-directed the acceleration is Rw^2. So, a gyroscope could measure w, and allow calculation of the acceleration.
The current method of rotation is through a simple bearing that is lodged in the pendulum. A shaft runs through it and connects one pendulum to another.
I was thinking that a slip-ring-sized hole could be drilled into the diameter of the shaft and placed inside, and another hole for the wires could follow suit. I don't have any experience with a slip ring, however, so I am not sure whether one slip ring would work or whether we'd need two.
In regards to the communications being unreliable, I'm guessing the slip ring may interfere with the data of the wire? If this is due to something else please correct me.
Considering that all, a gyroscope does sound more useful for measuring data, but wouldn't it have the same problem as the accelerometer for the communications?
I've ordered some slip rings and accelerometers, so I will be able to begin to understand the kit once they've arrived.
How many hours of work does a slip ring normally take for data to be distorted? I read a source online saying that they start off clean and become noisy through use and so I'm just wondering whether I need to worry or not. For some clarity, this system is for a 24 hour art installation and so if the slip rings do their job for that brief period of time everything should be fine.