Affect of acceleration on the gyro: LSM6DSL, LSM6DSO, LSM6DSR

[Singh.Harjit]

I want to use the ST MEMs IMU in a high acceleration environment - example could be race car, drone, remote control car, etc.

I'd like to know how the gyro behaves under acceleration.

For example, Analog Devices calls this parameter:

* Linear Acceleration Effect (degrees/second/g)

* Vibration Rectification (degrees/second/g^2)

The reason I ask is that another company makes a six axis IMU where the gyro in old version was not very sensitive to acceleration but the new one is very sensitive.

Thanks.

[Eleon BORLINI]

Hi @Singh.Harjit​ , these are interesting parameters. From our experience, there are two main factors that contributes to an eventual acceleration affecting the gyro behavior (unwanted noise floor): the amplitude and the frequency of the disturbance, and this impact is basically due to the internal structure of the MEMS. Which are the vibration intensity and the frequency range of your interest / application? For example, the gyro-only device L2G2IS (or the OIS parts of the IMUs) is optimized for the Image stabilization, managing the frequency range of the hand vibrations. And, other than ADI, are there other IMU vendors you compared, if I can ask you? Regards

[Singh.Harjit]

The explanation of the sensing of acceleration by the gyro makes sense. Unfortunately, I don't have a frequency / magnitude spectrum.

I would like to sample the IMU around 3kHz to 4kHz. I expect the device to experience up to +/- 4g acceleration and around 1200 deg/sec rotational velocity.

The bandwidth of the L2G2IS is too low for my application.

From reading about the Invensense ICM-20602, the gyro is more sensitive to acceleration compared to the older Invensense MPU-6xxx parts. Invensense introduced the ICM-20689 but I do not know how it compares to the MPU-6xxx part.

This paper talks about vibration sensitivity of gyros: Vibrations Rejection In Gyroscopes Based On Piezoresistive Nanogauges (https://core.ac.uk/download/pdf/55253035.pdf).

I think having similar data for the ST parts would be great.

[Singh.Harjit]

In researching ST's gyros, a friend pointed out TA0343 - Everything about STMicroelectronics’ 3-axis digital MEMS gyroscopes.

This talks about the construction of the sense element. Are the LSM6DSL, LSM6DSO, LSM6DSR constructed using the same type of structure i.e. a single driving structure design?

[Singh.Harjit]

Help?

[Eleon BORLINI]

Hi @Singh.Harjit​ , thank you for the explanation. Basically yes, the evolution of the mechanical structure of the (capacitive) IMUs has been in the direction of integrating the accelerometer and the gyroscope sensors, especially along x and y axis, but the actuation frequencies of the active element of the gyro are far away the typical acceleration sensed by the accelerometer part, and properly filtered, so there is no fear of a frequency disturbance overlapping. Regards

[Singh.Harjit]

Do the LSM6DSL, LSM6DSO, LSM6DSR use a single driving structure?

[Eleon BORLINI]

Basically yes