We’re inclined to think you’ll love this week’s EYE ON NPI (video), since it’s the Murata SCL3300 Series 3-Axis Inclinometer, a really unique and useful sensor that can be very useful for industrial and robotic applications.
Inclinometers measure…incline! That is, the angle of tilt of the sensor and the platform it’s placed on. This is useful when you want to make sure something is perfectly straight or flat with respect to the center of Earth’s mass. If a robot or piece of construction equipment isn’t perfectly level, errors can build up and construction projects can end up with big flaws, gaps or repairs. Not good!
Now experienced engineers (including ourselves, before we researched this part) may be wondering: wait, if you’re measuring tilt with respect to the earth, why not just use an accelerometer? Accelerometers measure acceleration, and gravity is an acceleration force everything on Earth is affected by, so you can easily do some math on the number of g’s measured by an accelerometer and convert that into tilt with a little math as shown by this detailed ST app note.
So why have a special sensor called an inclinometer, and why does it cost much more? Well, accelerometers can be used for rough tilt calculations, but they’re not really designed for it.
They tend to be used for ‘gross motion detection’ like taps, jerks, big angles. For that reason many everyday accelerometers are maybe 10 to 12 bits of precision and +- 2g to +-16g. That’s fine for motion detection, but not precise enough for minute changes in tilt, where only a few mg of change in gravity can affect the angle. So you can think of an inclinometer as a special type of accelerometer, with very low g rating, and very very high accuracy (how close the reported value is to reality) and high precision (how many digits you can squeeze out of the measurement)
So, for example, a common accelerometer may have at +-2g a precision of 1mg per LSB, whereas the SCL3300 in inclination mode has a precision of 12000 LSB/g (which is 12 LSB/mg and 0.08 mg/LSB). The noise density on a common accelerometer is about 220 μg/√Hz, on the SCL3300 is as little as 15 μg/√Hz. The temperature and offset stability are also going to be much better. Basically, it’s very very precise, but not designed for moving fast – that’s what a high g accelerometer would be for!
For detection of small changes, or small angles, the Murata SCL3300 Series 3-Axis Inclinometer will do the job much better than an accelerometer, with a simple SPI interface that will integrate quickly with any microcontroller or microcomputer. We especially like that the SPI interface has CRC and error monitoring, important for critical installations. And for such a precise sensor, the price is very good as well!
The sensor is available on an easy-to-use eval board if you want to start prototyping fast. Both sensor and eval board are in stock right now for immediate shipment from Digi-Key. Order today and you’ll be inclinating (that’s a word right?) by tomorrow afternoon.