So I want to measure the angle of this folding hinge with arduino, and I've considered a few methods of doing so (As indicated by the green lines in the image attached). Either using a rotary encoder or using IR sensors. I need accuracy of the order of +-0.5 degrees. A non contact method of doing so would be ideal. Are there any better ways of doing this? Please do let me know! Thanks in advance!
Points A and B being the ends and point C being the hinge point...... place sonic transmitter at A, focus on B, receiver at B....measure hypotenuse, calculate angle.
Can you attach a potentiometer to the hinge?
...R
bluejets:
Points A and B being the ends and point C being the hinge point...... place sonic transmitter at A, focus on B, receiver at B....measure hypotenuse, calculate angle.
You'll have to ensure a clean line-of-sight across all possible angles == tricky
bluejets:
Points A and B being the ends and point C being the hinge point...... place sonic transmitter at A, focus on B, receiver at B....measure hypotenuse, calculate angle.
Seems like this would be a bit complicated. Attaching the sensors mainly. But I suppose this could be one option. But thank you so much for your input!
Robin2:
Can you attach a potentiometer to the hinge?...R
Not at the hinge, but it might be possible to attach a string to the edge of the folding piece and then connect that to a pot. Not sure if that makes things complicated though.
sreshtiyer:
Not at the hinge, but it might be possible to attach a string to the edge of the folding piece and then connect that to a pot. Not sure if that makes things complicated though.
A lever may be better rather than a string because a string cannot "push". Something like this?
...R
Robin2:
A lever may be better rather than a string because a string cannot "push". Something like this?
...R
Hmm, this is interesting! Might try this! But for now, my team is using a camera with a Pi to detect angle, but I shall still look for a way this can be done in an arduino. Will try this and see how it works. Thanks!
With the above sketch, you will have to work out the log measurements for the linear hinge travel.
i.e. as the hinge goes "around the corner" the pot does not move as much.
That's why Robin2 said "at the hinge".
A wheel locked to the moving arm and centred on the hinge line with a "thread" running to a similar wheel(either through pulleys or direct) mounted on a potentiometer will give linear readings.
To overcome the "pull but not push" the thread, simply add a small weight to the overrun at the pot or a small "clock spring" on the pot.
Or indeed a "dial cord" arrangement.
What about a flexible coupling? Keep everything as close as possible to the rotation axis and it might work.
I'd go for a pot at the hinge point. So it makes a 90° turn together with the door. A typical pot has 270° rotation, so you get only 1/3 of the total range - but that's OK. That still gives you some 341 ADC points of range, and a resolution of 0.26°. Add two sprockets and you can get that to the full range of the pot. A 10k pot, one end to Vcc, one end to GND, slider to the analog input.
The hardest part is going to be the pot's precision and reproducibility over such a small range. You're likely to encounter hysteresis.
wvmarle:
I'd go for a pot at the hinge point.
My drawing was prepared on the assumption that it would be difficult / impossible to mount the pot with its axis in line with the hinge axis. I think to do that it would be necessary to cut away part of the door and part of the door-post.
As far as the control goes my idea is the same as yours.
...R
dougp:
What about a flexible coupling? Keep everything as close as possible to the rotation axis and it might work.
Your diagram looks like the opening door would "push" your flexible coupling. Is that you have in mind? I don't see how that would cause the pot to rotate.
I am assuming the hinge axis comes out of the image and the door opens by swinging to the left.
...R
I guess “why do you need to do this ?” May elicite a few more possible solutions
Robin2:
I am assuming the hinge axis comes out of the image and the door opens by swinging to the left.
Attempt to clarify.
How about an encoder and interrupter. If you need fine detail you can gear it down using pullys or gears... Yeah the end use would be helpful. If it's just open and shut then any limit sensor would work. we really need more detail.