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I'm building an app which analysis the step of the person that wears the sensor, and I haven't found and mention in the API or the exapmle apps for what are the unit of measurement (in the linear acceleration and angular velocity).

I believe that timestamp is milliseconds (correct me if I'm wrong), but what are the others?

Thanks!

Barak Ohana
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  • What are you trying to say here: "which analyis the step of the one that whear the sensor"? – NetMage Dec 05 '17 at 22:38
  • Fixed the unclear (and very weird) sentence (sorry for that, I'm not native with english, so I sometimes write weird stuff by mistake). Hope it's more clear now. Anyway, its not relevent to my question. – Barak Ohana Dec 05 '17 at 22:45
  • Since your question doesn't mention which device, whose API, what OS or language, or what data types, I was hoping knowing what you were trying to do would provide a clue. – NetMage Dec 05 '17 at 22:48
  • @NetMage He tagged it as "Movesense", so it is a movesense. – Dotevo Dec 06 '17 at 07:29

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Time Api returns data in uS

$ wbcmd --port com9 --op get --path Time { "response": 200, "responsestring": "HTTP_CODE_OK", "operation": "get", "uri": "/net/ECKIB9870DA4/Time", "content": 1420070440653000, "querytimems": 26, "querytimens": 26918122 }

But Timestamp for Acc goes from the LSM6DS3 chip and it is in mS.

$ wbcmd --port com9 --op subscribe --path Meas/Acc/13 /net/ECKIB9870DA4/Meas/Acc/13::onSubscribeResult Subscribed and listening for notifications. Press ESC to stop:

@191 { { "Timestamp": 158, "ArrayAcc": [ { "x": -0.07657305896282196, "y": -0.66044265031814575, "z": 9.9186038970947266 } ] } }

@255 { { "Timestamp": 235, "ArrayAcc": [ { "x": -0.11485958844423294, "y": -0.64129936695098877, "z": 9.9377470016479492 } ] } }

@383 { { "Timestamp": 312, "ArrayAcc": [ { "x": -0.052643977105617523, "y": -0.6341206431388855, "z": 9.9329614639282227 } ] } }

You have to know that LSM chip doesn't have any good clock. So real timestamp can drift a little (depends on temperature) like +-2%.

Dotevo
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  • I thanks you so much! Do you know what are the units of the linear acceleration and angular velocity? – Barak Ohana Dec 09 '17 at 22:43
  • @user3195363 Here is the best place to check: https://bitbucket.org/suunto/movesense-device-lib/src/a08789c38c4ad7fed623950dc9fdb4c643dd7534/MovesenseCoreLib/resources/movesense-api/?at=master LA: x-unit: m/s^2 Gyro: x-unit: dps (degree per second) – Dotevo Dec 11 '17 at 07:42