can anyone replicate this?

[blort1961]

Used in the control of rc subs.

 

[cowboybob]

By replicate, do you mean build one from scratch? Or adapt a PCB accelerometer/gyro PCB to control a servo?

 

[jpanhalt]

Gyro (aka accelerometer) controls are standard fare in many models, particularly in aircraft and helicopters with one or more rotors. One option is to buy a complete model and scavenge the gyro and servo circit. Alternatively, you can buy the gyro chip already designed to operate a servo. Finally, you can buy the bare chips fairly cheaply and build your own circuit. You will need a microcontroller and be able to program it to do this last approach.

Please let us know more about your project and how you want to approach it.

John

 

[ClydeCrashKop]

Just add PWM for the servo to this: ADXL345 Accelerometer and 18F4550 in Hi-Tech C

 

[blort1961]

By replicate, do you mean build one from scratch? Or adapt a PCB accelerometer/gyro PCB to control a servo?

Gyro (aka accelerometer) controls are standard fare in many models, particularly in aircraft and helicopters with one or more rotors. One option is to buy a complete model and scavenge the gyro and servo circit. Alternatively, you can buy the gyro chip already designed to operate a servo. Finally, you can buy the bare chips fairly cheaply and build your own circuit. You will need a microcontroller and be able to program it to do this last approach.

Please let us know more about your project and how you want to approach it.

John

This is specifically for rc sub work so the plentiful (and cheap) modules out there for Airplanes will not work.

I mean adapt a existing module to do this...they HAVE to be less expensive than existing modules that approach $100.00 or more

 

[jpanhalt]

This is specifically for rc sub work so the plentiful (and cheap) modules out there for Airplanes will not work.

Why won't they work?

I mean adapt a existing module to do this...they HAVE to be less expensive than existing modules that approach $100.00 or more

You have already been given some leads to very cheap modules and have rejected them. If you want something specifically designed and made for model submarines, you are going to pay a steep price.

John

 

[blort1961]

Basic info on how RC Sub Autolevellers work in comparison to RC Airplane ones:

The Auto leveler will work the stern planes to keep the boat level when no input from the transmitter is received. When you apply input to your transmitter, the receiver will act on that input overriding the auto leveler for the most part.

The auto leveler will return the boat to level when you release the tx input.
To dive and rise a submarine requires very little input, the auto leveler trying to counter act the tx input is not enough so the input to the planes will be more than the auto leveler.

Example. You input in 25 degrees of dive. The auto leveler will try of correct the nose down but the auto leveler may only put 5 degrees up. You still have 20 degrees down on the planes. Not real numbers. Just illustrating .

IM LOOKING FOR A BEETER ILLUSTRATION THAN THIS>>>STAND BY

 

[blort1961]

I think this short statement says it the best:
A sub leveller is like a gyro that is constantly referenced to the horizon (thinking in aeroplane terms). A gyro references to the last commanded position and keeps it locked there (as best it can).

 

[jpanhalt]

Basic info on how RC Sub Autolevellers work in comparison to RC Airplane ones:

The Auto leveler will work the stern planes to keep the boat level when no input from the transmitter is received. When you apply input to your transmitter, the receiver will act on that input overriding the auto leveler for the most part.

How is that different than an accelerometer on an airplane stabilizer/stabilator/elevator?

The auto leveler will return the boat to level when you release the tx input.

Same with airplanes.

To dive and rise a submarine requires very little input, the auto leveler trying to counter act the tx input is not enough so the input to the planes will be more than the auto leveler.

Again no difference between a sub and an airplane when the sub is about neutral buoyancy. Now, if the sub takes on water to dive, there in no comparable mechanism for airplanes to add water or mass while in flight (excluding in flight refueling ). However, some aircraft (e.g., sailplanes) routinely carry water ballast, which they can jettison to control their flight characteristics.

An accelerometer controlling a servo to maintain or change a control axis is no different in a sub than in an airplane. You may be confusing gyros that have a rotating wheel with modern accelerometers. Some use a vibrating weight, and others have no moving mechanical parts at all. They do not have to be reset periodically to a horizon.

John

 

[blort1961]

How is that different than an accelerometer on an airplane stabilizer/stabilator/elevator?

Same with airplanes.

Again no difference between a sub and an airplane when the sub is about neutral buoyancy. Now, if the sub takes on water to dive, there in no comparable mechanism for airplanes to add water or mass while in flight (excluding in flight refueling ). However, some aircraft (e.g., sailplanes) routinely carry water ballast, which they can jettison to control their flight characteristics.

An accelerometer controlling a servo to maintain or change a control axis is no different in a sub than in an airplane. You may be confusing gyros that have a rotating wheel with modern accelerometers. Some use a vibrating weight, and others have no moving mechanical parts at all. They do not have to be reset periodically to a horizon.

John

Im not certain why, other than the aforementioned explanations, but many people "in the know" state that Airplane units cannot be used in submarines. Subs don't ALWAYS take on water to dive, often they are forced under water by the speed of the sub as well as the angle of their rear dive planes (where autolevellers are used). Front planes are used for stabilization only

 

[blort1961]

Here is a more comprehensive discussion:
https://www.modelboatmayhem.co.uk/forum/index.php?topic=36009.0

 

[jpanhalt]

That article must be way over my head. I simply didn't understand how it compared submarines to aircraft in any way that claimed aircraft controls couldn't be adapted to submarines. In fact, I didn't see a single mention of or comparison to model aircraft accelerometers ("gyro's"). As for modern accelerometers (i.e, excluding bubble levels, lead weights on strings, and similar) only the two types that I mentioned above were mentioned in the article. There is one type of "trainer" leveler that was used in model airplanes several years ago. It did sight on the horizon. Maybe it is still made, but I can't imagine why it would be used.

There was quite a bit of verbiage spent on bemoaning electronics made with surface mount devices (SMD's), but hey, get used to it. Many components today cannot even be bought with through-hole pins. Of course, some enterprising individuals take a $4.50 retail chip that they get wholesale (e.g., the Memsic accelerometer mentioned in your link), attach it to a TH adapter board, and sell it for $25.00 at Radio Shack. That is not a difference between airplanes and submarines. It is the difference between the 1980's and the 21st century. Can't fix that. If you want some very old (Apollo) servos with TH components, I would be happy to sell some to you, but they are quite rare and will be expensive. (sarcasm)

I suspect you need more experience with both submarines and model aircraft, as you really seem to be missing the similarities. What is really puzzling is that the illustration you gave in your opening post used exactly the components I have tried to describe. You wanted to "replicate" it, but you reject suggestions about how to do that.

John

 

[blort1961]

wow, that's quite a comeback. I didn't pen the articles that I gave links to. They may be relatively old, which may be why they say what they do about smd...I don't know, again , these links are not mine.
I do have a relatively secure knowledge about RC subs, just not Autolevellers.
I haven't rejected anything, I just have stated that every article I have read states that the units that are used for RC planes will not work in RC Subs, I just cannot find a article with a comprehensive description as to why.
I guess I will just have to consider this link closed, until I have further info to support this.

 

[audioguru]

My rc airplanes have elevator, rudder and aileron accelerometers that do not level the airplanes. Instead the accelerometers correct for quick changes in orientation caused by air turbulence. Then when I am not making control adjustments the airplane flies very smoothly like a much larger airplane that uses inertia from its weight to fly smoothly.

 

[Tony Stewart]

Looks more like a MEMS gyro than an accelerometer.
Accelerometers use double integrators from g to get displacement in each axis and tend to drift too much for DC control.

 

[jpanhalt]

Tony,

What you are describing sounds like the old inertial navigation units of the 1970's ans 80's. The device demonstrated by the op and discussed in the links he gave is also an acelerometer and works similarly but it is not double integrated to get distance. Their main use is to measure tilt relative to Earth's gravity. Of course, if you displace them rapidly you see the effect, but they settle relatively quickly to give tilt. They do not drift in that regard. I have left one for several days on a table and the reading didn't change. Ian uses them in devices he makes for crane operators.

John

Edit: You may find these links interesting and on-topic:

Accelerometer for roll and pitch:
https://ww1.microchip.com/downloads/en/AppNotes/00996a.pdf

Parallax application kit:
https://www.parallax.com/sites/default/files/downloads/28017-Memsic-2125-Accel-AppKit.pdf

Freescale tilt sensing:
**broken link removed**

 

[ronsimpson]

My rc airplanes have elevator, rudder and aileron accelerometers

My airplane has a rubber band.
**broken link removed**

 

[audioguru]

The biplane was new last year and the ducted fan jet is about 1 month old. Both use accelerometers.

 

[ronv]

My airplane has a rubber band.
**broken link removed**

My last one is on the other side of the golf course....... Somewhere.

 

[DerStrom8]

My last one is on the other side of the golf course....... Somewhere.

When I was in college I took one of those balsa wood airplanes (no propeller--just a glider), lit the tail on fire, threw it out the third story window (it had been raining so it wasn't a fire hazard) and watched it crash and burn. Never had any since then.

I did some crazy stuff when I was in school....