This is a quick article to clear up some confusion between the various offerings of the InvenSense MPU inertial sensors to show which is currently best for FPV racing flight controllers. All of the MPU/ICM range of sensors include a built in 3 axis accelerometer and a 3 axis gyroscope into a tiny chip!.
!(/content/images/2016/11/m2pu60001.jpg)Right now the MPU6000 is the most popular IMU sensor used on just about all the best flight controllers. Reason being is that it it can sample the gyro at 8kHz via an SPI bus, and also has great vibration tolerance. One thing to watch out for is to make sure this sensor is connected via SPI to the processor to get full use of the high speed updates.
!(/content/images/2016/11/rp-mpu-6500.png)The MPU6050 is exactly the same as the MPU6000 above, however it talks on I2C protocol, it is not often used on flight controllers because I2C is just too slow for this sort of thing and cant read the gyro at 8Khz. I would stay away from any flight controllers using this sensor.
!(/content/images/2016/11/rp-mpu-6500-1.png)The MPU6500 is newer than the above IMU sensors, but is not as popular. This IMU allows up to 32kHz updates from the gyro, and the gyro is more sensitive which is usually better right? Well because of this extra sensitivity it is more susceptible to vibrations so you often need to use some [vibration isolation methods](http://www.dronetrest.com/t/quadcopter-vibration-damping-for-flight-controllers/33) like foam when mounting this flight controller.
However this reputation for poor vibration tolerance is largely a function of the flight controller not using the full 32Khz gyro update rate as few flight controllers are powerful enough to sample this sensor any faster than 8Khz. This means that the FC is only getting every 4th reading, of which some can be seriously affected by vibrations. By using a more powerful flight controller (using STM F4 or F7 processor) you can get readings at the full 32Khz which largely reduces the negative vibration effects.
So as long as your flight controller is rocking a STM F4 or F7 processor and your firmware supports up to 32Khz update rates then this is the one to go for. Currently only BetaFlight and RaceFlight support 32Khz gyro updates, but CleanFlight will also soon add this.
!(/content/images/2016/11/rp-icm-20602.png)This is one of the newest IMU's from InvenSense suitable for use on drones and it features much more accurate sensors with less noise. It can also get gyro readings at 32Khz so will be a great option for future flight controllers that have more processing power like F4 or F7 boards. This IMU is starting to show up on the latest boards like the [Omnibus F4 V3](https://www.unmannedtechshop.co.uk/omnibus-f4-v3-flight-controller/), or [SPF4 Evo flight controller](https://www.unmannedtechshop.co.uk/sp-racing-f4-evo-flight-controller/). But I am sure in the future this will become the standard IMU sensor on flight controllers!
What about the 9 or 10 DOF IMU sensors?
There are a collection of other IMU sensor chips with extra sensors like a compass, and other brands also make them. However in the case of InvenSense (first company to make an all in one IMU sensor chip), the other sensors within the family are essentially the same chip, but with an added compass (magnetometer), for example:
- MPU9150 is based on the MPU6050 with and added compass
- MPU9250 iis based on the MPU6500 with and added compass
Want to know more, check out our guide on how to buy the best FPV racing flight controller
Otherwise if you have any questions, comments or suggestions just let me know!
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