How to Validate the acceleration data?

[Shivam Paliwal]

We are using LSM6DSOXTR Sensor for getting the acceleration

Accelerator data coming from ST Sensors showing very high value of acceleration,

when compared to other Product such as YYY brand.

We mounted ST Sensor on an Industrial equipment, we get Acceleration data in mm/sec2 as below.

(We converted from mg to mm/sec2 by ((value in mg/1000)*9806.65) )

Y(in mm/sec2)	X(in mm/sec2)	Z(in mm/sec2)
8904.4382	4462.02575	5913.40995
9649.7436	5040.6181	3196.9679
10042.0096	2098.6231	696.27215
10865.7682	-961.0517	4177.6329
10669.6352	-6040.8964	3206.77455
10238.1426	-3991.30655	4001.1132
9306.51085	-1078.7315	1490.6108
9590.9037	2000.5566	98.0665
8227.77935	176.5197	-1990.74995
8727.9185	-2441.85585	3628.4605

When we mount Sensor from other brand YYY , and measured vibration for same condition, we get below values.

x(in mm/sec2)	y(in mm/sec2)	z(in mm/sec2)
9.439	7.57	1.122
8.785	6.168	5.327
6.823	2.056	5.047
8.411	1.963	3.084
9.907	6.262	6.262
7.29	3.178	9.253
5.327	2.71	11.776
6.823	1.963	20.374
5.421	1.589	24.113
0.467	0.935	22.43

There is huge difference between these values coming from 2 sensors for exactly same conditions.

We then calculated VRMS from acceleration data from ST Sensor and YYY sensor. With ST sensor it is coming abnormally high data.

Effectively we understand acceleration data coming from ST sensor is high value than it should be, but we are not sure, reason for this.

When we just keep ST sensor on stationary surface, we get acceleration data in mm/sec2 as below. (converted from mg)

X in mm/s2	Y in mm/s2	Z in mm/s2
9.80665	     166.71305	     -9747.8101
127.48645	166.71305	-9688.9702
176.5197	98.0665	       -9620.32365
147.09975	58.8399	       -9728.1968
78.4532	       78.4532	       -9581.09705
166.71305	88.25985	-10581.37535
-29.41995	313.8128	-9796.84335
68.64655	156.9064	-9433.9973
98.0665	      156.9064	         -9767.4234

This looks to be very large. Can you please throw some light??

Regards,

Shivam

[Shivam Paliwal]

Hi @Eleon BORLINI​ 

Can you Please guide us on above topic.?

Regards,

Shivam Paliwal

[Uwe Bonnes]

You can validate on a sensor in rest. The square root of all 3 axes added squared should give the g value at your site. Consider offets and gain variation in all 3 axes. Rotating in 3-d so that one axis is maximum in rest should give offset for the other axes an gain for that axis.

[Shivam Paliwal]

Hi @Uwe Bonnes​ 

Thanks for your reply..

We have taken some reading(in mg) when sensor is at rest .

Below are some readings in mg..

X in mg	Y in mg	Z in mg
1	    17	-994
13	    17	-988
18	    10	-981
15	     6	-992
8	     8	-977
7	    16	-962
10	    16	-996

Maximum offset can be +- 20 mg as per the datasheet of sensor.

But all these values looks high when we convert it in mm/sec2 and compare with some other *** brand's vibration sensors(Values are added in above main questions) ...

Values are much different, Even after doing the square root of all 3 axes added squared ,

so you please guide us on value differences..

and is there any way to calibrate the sensor?

Regards,

Shivam Paliwal

[Uwe Bonnes]

Did you measure mean values or dis you only take one sample. Did you hold in you hand? Think of some tremble. But as the datasheet only specifies typical values, and no min/max, all these values are inside the spec.

[Shivam Paliwal]

Hi @Uwe Bonnes​ 

Did you measure mean values or dis you only take one sample. Did you hold in you hand?

--> Sensor's PCB is lying on table, It was stable without any vibrations.

We had taken 2000 sample of X,Y and Z, Above values are just few samples from it .(However all samples are in almost same range)

But as the datasheet only specifies typical values, and no min/max

---> Datasheet says (±20mg, see datasheet, p.10).

 

[Shivam Paliwal]

I would like to bring to your notice the original issue we have.

Basically we mounted ST Sensor on an Industrial equipment, we get Acceleration data in mm/sec2.

The data what we got with ST Sensor is very very high compared to Sensor from other commercial product for same test conditions.

Readings from ST sensor as well as from other sensors is mentioned in original mail thread

.

We are looking for your guidance on why ST sensor is giving such a high value?

[Uwe Bonnes]

Look carefully. The value is in the row "typical"