With these motors (full rotation servos - no electronics; just motors) and the heavy weight of my bot, not a chance. Other robots I've seen can recover or stand up from prone. Botka, for instance:ericgibbs said:Never made a balancing robot, but my gut reaction would be, if the the robot got more than +/-37.5 deg off balance from its COG, would it be able to recover..??
futz said:With these motors (full rotation servos - no electronics; just motors) and the heavy weight of my bot, not a chance. Other robots I've seen can recover or stand up from prone. Botka, for instance:
**broken link removed**
Big grippy wheels and powerful motors combined with good controls can do amazing things.
Why I'm asking about gyros is because I don't understand what they mean by degrees per second. Does that mean how sensitive the gyro is? In that case, how sensitive do I want it to be?
I've been googling hard and am beginning to see what it means. So the higher deg/sec ones are capable of sensing higher rates of rotation. The lower rate ones would be more sensitive? Not sure about that part...ericgibbs said:From my experience with gyro's degrees/sec means the rate of change of signal output with respect to time.
As I said, not a chance. With different motors/wheels, maybe. Still unlikely. It's too heavy. If I designed a lighter one with less weight up top, yes.Do you expect your robot to get back upright if it falls over.?
That's what I'm shooting for, for now.or will it always be able to correct its balance before its does fall over.?
Bottom of this thread: https://www.electro-tech-online.com/threads/de-accm3d-accelerometer-junebug-a-d-question.38957/Its difficult to visualise your robot not having seen its configuration.
Me too. I was a Meccano maniac when I was young. Built tons of cool things with it. Too bad it got chucked many years ago.ericgibbs said:I used to have a mechano set as a child, great fun and educational.
Ya. Unfortunately I don't know how much or how little I need. I balance the bot with batteries in it and let it go. It takes (guesstimated) a bit less than a second to fall, so maybe a 75 deg/sec is not enough? I don't know!Ref the gyro, if I was designing a balancing bot, I would shoot for a high sensitivity, providing the motor response was able to cope and didnt send the mass into oscillation.
They're called inverted pendulums.Sounds an interesting project, bit like balancing a long pole at the end of your finger.
I've been to that site, but it does nothing for me. I just don't have the math chops for it.Papabravo said:The degrees per second refers to the angular velocity of the rotor. The faster it spins the more angular momentum it has and the greater will be the restoring force when the spin axis is displaced. See the following page
http://www.gyroscopes.org/math.asp
As for what is most useful, this REALLY depends on the project. A balancing robot would probably love the 75 deg/s part. An airborne INS would either need the 150 deg/s part or the 300 deg/s part (if you're doing tumble applications or have a very maneuverable design). You might be surprised how fast something can turn, especially in the first 5 degrees of a longer turn. Might top out the 75 deg/s part, maybe even the 150 deg/s part.
I think they still are mechanical inside the chip, but nothing rotating.Papabravo said:So we're not talking a mechanical device that generates forces when it is displaced? What's the point of calling it a gyroscope?
Papabravo said:So we're not talking a mechanical device that generates forces when it is displaced? What's the point of calling it a gyroscope? Sounds like a serious truth in advertising issue. This is like 1984
- War is Peace
- Love is Hate
- Truth is Beauty
https://en.wikipedia.org/wiki/Vibrating_structure_gyroscope3v0 said:Wikipedia says "A gyroscope is a device for measuring or maintaining orientation," but then it goes on to talk about angular moment. Maybe we should say the electronic units are gyroscope replacements.
From another site said:The next generation of gyro is the piezoelectric gyro.
Here, there are no spinning bits, only a rapidly vibrating crystal. This crystal wobbles along a particular axis, and as I understand it, turning the crystal will cause disturbances in this wobble which cause a small electric current. This current can be measured and used to adjust your servo position. Piezoelectric systems are very temperature sensitive since temperature affects some internal resistances. This is why they start to drift as the temperature changes. Most piezo gyros now have a temperature compensation circuit to avoid this.
The most modern kind of gyro is the MEMS gyro. MEMS = Micro Electric-Mechanical System. MEMS are molecule sized machines that are fabricated on top of a piece of silicon, along with the electronics to interface to them. I don't know how MEMS gyros work specifically, but they do some sort of differencing on some sort of moving bits
They're not SO difficult, but analog output is SO easy that it makes measuring pulse widths seem like such a pain. The SPI/analog ones don't cost any more, so that's what I'm going for.Sceadwian said:Why is a heli gyro too difficult to interface? They're designed to interface directly to a tail rotor control servo. 1.5ms center (no rotation) positive and negative rotation around it's axis will give you a proportionatly higher/lower pulse width based on the rotation change. For ballance rate of change direction isn't too much of an issue, it's update and responce rate for the correction and programming the control loop that are the difficult part.
Heh.Papabravo said:Which brings us full circle back to the original question about the measurement of an angular velocity in degrees/second and what it actually refers to. We think we understand the measurement for a mechanical gyro, but I am less clear for the other types exactly what angular velocity is being measured. Assuming we can get our arms around that one, then we need to understand how, as a figure of merit, we could apply different non-mechanical gyros to a given application. Like erecting our robots from a supine position. CMOL(Chuckling mildly out loud)
Tuning Fork Gyroscopes. Tuning fork gyros contain a pair of masses that are driven to oscillate with equal amplitude but in opposite directions. When rotated, the Coriolis force creates an orthogonal vibration that can be sensed by a variety of mechanisms.
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