问题
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!
回答1:
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%.
来源：https://stackoverflow.com/questions/47663799/what-are-the-unit-of-measurement