Moasure

[Tseralo]

Anyone know anything about this tool? It looks like it doesn’t use GPS and can export raw coordinates. Might be well worth a try especially with the price tag.

Discover Moasure

Moasure is a revolutionary new measuring technology that measures by sensing its position and movement in three dimensions. It uses inertial motion sensors to measure distance, height, level, angle, area and volume in a single measurement, simply by moving from one point to another.

moasure.co.uk

 

[aricooperdavis]

It's a pretty old concept, but processing noisy acceleration/inertia data is really hard, so I guess the real selling point of this is the "proprietary algorithm" they use. However, all the use cases seem to be closed loop - when you look at the videos of the measurements being taken and the resultant plan you see a super simplified polygon.

Who knows how well their algorithm could make sense of data from a cave? I suspect that's not a use case that they've got much training data for!

 

[pwhole]

Looks interesting. And at least they're UK-based, so handy for pestering. May be worth asking them if they've trialled it underground at least.

 

[Allan]

Sounds like it could be useful surveying old mines which often have lots of metal in them.

 

[Bob Mehew]

If you explore some of the Inertial Measurement Units such as the LSM9DS1 you will see them refer to 9 DOF (I presume Degrees of Freedom), see adafruit-lsm9ds1 for example. They use 3 acceleration sensors, 3 angular rate (gyro) sensors and 3 magnetic field sensors (so the 3 sensors point in the three directions at 90 degrees to each other.) Others work on 6, missing the magnetometer (its sensing rate is much slower). Moasure appears to work on just acceleration and gyro sensors. As Ari said, the detail will be in the algorithm. One thing I have found is they are limited in frequency of measurement (well limited for my sub milli second potential application) but it seems that approaching 1000 samples per second is all that is required for most applications in motion sensing. Though I suspect the military versions are more precise. Cheap to set one up to do some field experiments but no doubt expensive in time to work out the data processing. I did not manage to progress to a working set up.

 

[Steve Clark]

The biggest problem with inertial navigation systems is 'velocity drift'. In its simplest form you're taking acceleration data, integrating twice and churning out distance (position). You know the initial conditions, usually stationary. When the sensor moves (accelerates), it can start processing and figuring out it's velocity and hence distance to where it is. Any tiny error that gives an incorrect velocity results in huge errors in position that continues to increase with time. If it thinks it's travelling at 0.1m/s, when it's actually stationary it will be 360m out in an hour.

I've seen some adverts for this 'Moasure' thing and it appears that the procedure for using it is to stop at the end of each 'leg'. This is a big advantage. It resets the velocity initial condition to zero at the end of each leg. The velocity drift can only happen during the length of time of the 'move'.

This is quite an old video now, but it gives a good explanation as to how modern devices use sensor fusion & the kalman filter to make sense of multiple inputs, noise and drift.

 

[Tseralo]

As others have said it’s not going to be perfect and obviously there won’t be splays but if I can do as they claim it might be a useful tool in the arsenal. Especially as it’s IP67. I’m thinking of some of the more horrible wet crawls we have where you don’t really need splays to draw a tiny tube.

It would be interesting to see if someone from the BCRA CSG could reach out to them and ask if we could evaluate it.

 

[Steve Clark]

Some info on how to use it here :

Introduction | Moasure User Guide

www.moasure.com

Lots of tips about rapid moves (1m/s), short (in time) leg lengths and lots of pauses (for zero velocity reset/boundary condition). It looks like it's got some monitoring so you can tell if you're doing things that promote drift.

1m/s in a horrible wet crawl may be a bit much. Unless they are totally full of water of course

 

[Duncan Price]

I have the app on my phone - it is OK over short distances. I corresponded with the manufacturers several years ago and they confirmed it had been trialed for cave surveying with poor results.

 

[ChrisB]

I have the app on my phone

The original Moasure app (2019?) was a basic measuring app using the sensors in the phone. The device discussed in this thread is a dedicated hardware device that uses the phone as an interface and should be much more capable. The currently available Moasure app has no measurement functionality of its own, it's only an interface to the device, and so far as I can see the original app isn't available now.