Directly-connected Inclinometer

[redboat219]

I read a topic on Model Submarine Technology about directly-connected inclinometer as a pitch control device. The book discussed the principles but not how exactly to build one. The optical pendulum is easy. It's how to build and connect it to the servo electronics that's unclear. Anybody out there know how?

Red

[ramius-ii]

Inclinometer

Hi Red,
Normally, there is an output voltage from the device proportional to the angle detected. This voltage is applied to the input of a PIC (Programmable Integrated Circuit) and the output of the PIC uses a function called "pulse width" to generate the pulse for the servo. Best is to look at the program functions of a PIC or STAMP. At the Reynolds Electronics site (http://www.rentron.com/) you can find the PIC code and how to use it.

Best, Ed

[anonymous]

Hi Red,

Without wishing to curb

Hi Red,

Without wishing to curb your enthusiasm it is worth pointing out that the electronic designs in Model Submarine Technology are showing their age.

IMHO You would be best off working with a sensor (e'g accelerometer chip feeding a PIC driving a servo- as discussed by Ramius) Or actually just buy a level controller, they are becoming very affordable like most electronics now.

The optical pendulum is almost an on/off (i.e not a proportional system) and so if you wanted to try it it could drive a small geared motor which moves the control surfsce. You would need a slipping clutch or limit switches to prevent the motor stalling and it could almost be driven by an amplifier and relay - if you want to keep it really simple.

[hakkikt]

I think you are talking

I think you are talking about the translation of Brüggen's book "Technik der Modell-Uboote" into English. I have the original, which includes a drawing for connecting the inclinometer to a servo.
You have to open up the servo. Inside, there is a potentiometer that tells the servo what the position of the servo lever is. You connect the 3 wires of the inclinometer to the 3 connections of the potentiometer, so that the outputs of the two units are added (or subtracted).

I guess you know all that already, since we are looking at the same book in different languages. Sorry that I cannot help you more, I have never taken apart a servo myself . My book includes a diagram with the necessary connections - if that is missing, send me a PM and I will mail you a scan of mine.

[anonymous]

Lost in Translation!

Yes, the English

Lost in Translation!

Yes, the English translation does not make that clear. So it just connects across the potentiomer in the servo - that's clever!

You would do us all a favour if you could post a translation.

Oddy enough I have just received an inclinometer from Norbert Bruggen. A lovely job, tiny and only £50 - so my original comments hold.

Davy

[hakkikt]

Here goes, translated from "Technik

Here goes, translated from "Technik der U-Boot-Modelle". I write "feed-back" because if I leave out the hypen the forum program will only write "###".

"Directly connected inclinometer

The simplest way for making the signal of an inclimometer usable by a servo is the direct connection to the servo's feed-back-value potentiometer ("poti"). What we want to use here is an inclimometer without evaluation electronics, for that is the very thing that that we want to avoid having - so we use one with optical sensoring. The two photo transistors are connected parallel to the poti, by which they make the servo's evaluation electronics believe that there is a different feed-back value than there really is. The electronics correct this by moving the poti - and thus the rudder - correspondingly. The information from poti and inclinometer are effectively subtracted, which is equivalent to the comparison of set-value/feed-back-value in the abstract loop that has been formulated above.

In practice, this version has been tested with servos whose poti uses a pure DC of about 2.5V. This is the case e.g. with servo electronics using the IC NE544. The sensitivity of the inclimometer can be set via the brightness of the LED (through R1) or via a resistor (R2). Leading regulation (PD controller) cannot be realised with this version.

Unfortunately, it is unavoidable that the maximum travel of the servo becomes larger than it was before the surgery. If there are mechanical travel blocks in the servo or in the rudder linking, the motor can be blocked, which may damage it if it occurs frequently."

[redboat219]

Thanks Hakkit. I have the

Thanks Hakkit. I have the same illustration. Like you I've never performed surgery on a servo. Is it just really a matter of soldering the optical sensor to the servo pot?

[anonymous]

Thanks for the translation.

Looks well

Thanks for the translation.

Looks well worth trying - a clever mod and servos are quite cheap.


Davy

[anonymous]

Hi hakkikt,

Sorry about troubling you

Hi hakkikt,

Sorry about troubling you for the translation. I read the chapter again and the text IS there. The chapter is a little jumbled and hard to read.

Most of the electronics is also rather out of date with lots of errors in it so I wouldn't try anything more than than the optical inclinometer which looks neat and simple.

I have a had a chance to try Norbert Bruggens latest stamp inclinometer and I am very impressed by it. So I would recommend getting one if you don't want to do your own experiments.

Davy

[hakkikt]

redboat,
from what I see in

redboat,
from what I see in the text & diagrams, that seems exactly what this is about - soldering the inclinometer wires to the poti. Looks doable to me, I considered it myself. It has this "I did it with my own hands" flair
But when my Seawolf project ever comes that far, I will probably try something neat & compact, like the Brüggen stamp inclinometer (as Davy recommended).