Inclination Sensor

  • Thread starter Malcolm Moorhouse
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Malcolm Moorhouse

I need to measure the inclination of a forestry vehicle, previously a pot fitted with a pendulum has worked well in less rugged applications . I'm concerned the rough ride will wreck the pot in no
time at all, one suggestion I've had is to fit the pot in an enclosure filled with silicone oil. Can the forum members offer any suggestions for a low cost sensor

Malcolm Moorhouse

Fong Kin Fui

Hi Malcolm

How about using an accelerometer? I have used products that used Analog Devices accelerometer chips ( from Crossbow
( for 2-axis inclination measurements. The thing you have to be worry about are vibration range (max g), bandwidth and the accuracy when choosing the product. Also, if you want low cost, you may even get away with just
using Analog Devices' evaluation boards (

Fong Kin Fui

Eduardo Hoyos


Analog Devices and Motorola have accelerometers than can be used like inclinometers.

Eduardo Hoyos

Anthony Kerstens

Surplus aircraft sensors? Your local electronics
sales/repair shops might help. You might even check aircraft magazines at a library.

Anthony Kerstens P.Eng.

Randy DeMars

If you are OK with the pendulum and just question the pot, you could mount a cam on the shaft of the pendulum, and use analog proximity sensor to read the position of the cam. Turck makes one
that gives a 0-10VDC signal when the target (cam) varies from 2mm to 4mm from the face of the sensor. It operates off of a 12 VDC supply.

Clark Southoff

Hi Malcolm:

The silicone oil may vary in its viscosity under different temperatures. The constant motion over the same area of the resistive material.

An alternative is the KMZ series of magneto resistive sensors from Phillips. The also carry angle sensors. The pendulum can be dampened by magnets as well. This solution may not be bargain basement, but it has reliability and

Best regards
Clark Southoff
Technology Wranglers Inc.

Vic Ellescas

Have you looked at the Spectron Sensors they're excellent but expensive and depending in you applications. I don't know the Spectrons website but try calling (516) 582 5671 (Hauppauge, NY).

I have used a device for this exact purpose in a slipform curb pouring vehicle. You're right, the pot will die. After giving up on pots, we went
to a sealed encoder from BEI with a pendulum suspended in multi-viscosity oil. The index pulse was used for the level indicator, as the encoder is not an absolute device. We went through a trial and error learning trial for the length of the pendulum, and it ended up about 50 cm. long. Our ambient operating temperature range was limited by what temperatures you can pour concrete at (roughly 0-40 C); if you have a wider range, oil selection may become more critical. The only other problem I remember that's worth mentioning is that we started out by using the most rugged encoder housing, which was cast aluminum. We had to eventually change to a formed aluminum cover sealed with silicone because the porosity of the casting allowed water to get in, eventually ruining the electronics. The units we used already came with a mil-style circular connector. In retrospect, the sensor worked very well and had the advantage of being easily "understood" by field maintenance people. A pendulum in oil is not a mysterious device!

This particular machine also had encoders with wands that touched a stringline; the encoders in these positions were subject to getting hit and
ruined, so we eventually devised a way to use linear Hall effect transducers instead of encoders. This involved placing a magnet on the
pendulum, and attaching the Hall sensor to the housing. Because of all the other factors involved with putting electronics on a vehicle, I used an AD654 VFC for the analog-to-digital conversion. This was simple (5 cheap parts per channel), easy to optoisolate, provided some built-in filtering, and made the input section was very rugged. The only disadvantage with the
Hall transducers was that their outputs had to be calibrated, so the machine had to be tilted to one side, then leveled, then tilited to the
other side during production. This info was stored in EEPROM, and could be redone in the field by a moderately well-trained technician or an idiot with a cell phone.

Looking back, each method (encoder vs. Hall sensor) has its pros and cons. I eventually preferred the Hall device because of its simplicity and ruggedness. The Hall device costs less than USD 5, whereas the encoder was over USD 100. The front-end electronics is also slightly cheaper. It was more of a pain to get all the software and hardware issues worked out, though. Most of the machines are still in operation, even after ten years of rugged service. And the pendulum was not a failure point, even with
encoders. You could also use a resolver, but this would add more cost up front and I don't know if you'd gain much except complexity.

Hope this helps, and I'll be happy to address more specific questions if you have them.


Willy Smith
I have not used one, but there are gyro modules available for model helicopters. I think Tower Hobbies has some for around $100.

I would be interested in hearing about your final solution.

Ed M.

Speaking for me, not for Starbucks. . .

Anthony Kerstens

Wouldn't a gyro module for model helicopters be
about stabilization, not sensing?

A helicopter gyro would not work for position sensing as its DC or steady state errors are too large due to drift . A cheap accelerometer would work, check out Analog Devices and their ADXL202, it is perfectly capable of being used as a tilt sensor . Being a micromachined silicone sensor has no moving parts, no fluids, highest reliability and probably lowest cost. IF you need
various types of output options check out Crossbow which is using the ADXL in a few different small modules.

In case anybody needs the URL for Crossbow, it's (not I also looked up the AD part. Looks like a really good way to go, if I had had these parts ten years ago it would have made my mobile application a lot easier! Now I just need an excuse to get some samples and play a little.

Also, here's the URL for the AD part:

There's also an app note for using the part as a combination tilt sensor.


Willy Smith
Numatics Inc.
Costa Rica
I seem to have some trouble with that same project. If anybody would give me a link to a webpage with the same project please respond back.


> I seem to have some trouble with that same project. If anybody would give me a link to a webpage with the same project please respond back.
I think, you can go for the Tilt sensors which has a full range of angles up to 360degrees. This types of sensor are manufactured by THE FREDRICKS COMPANY, USA. You can browse for more details

WIth Regards

A.Kunni malai Samy