Hi
I am adding external imu to my pixahawk which currently has mpu6000. I will use spi for the imu. I have three imus as options - which one is best for quadrotor performance (best vibration and other criteria) -
So which imu is best?
What problem are you trying to solve?
MPU9250 is basically an MPU6000 with compass. This is still a solid IMU but the ICM42688 is better IMO. Can not tell you about the differences between 45686 and 42688. Guess the first one with “balanced gyro technology” is more expensive and therefore less common.
What issues are you facing with the MPU6000 that affects your flight?
I would say the best lipstick to put on that pig is a ADIS16470 IMU.
What? Costs twice the drone itself, haha
Yea, I know. That’s the joke. Another dated analogy is “Spinners on a Yugo” but I suppose that’s regional.
Trying to add redundant imu
Would be happy to put it if someone could sponsor it lol
But the real question is whether you really want it for your drone. Maybe you can use another MPU or the ICM one just as well.
Just to confirm that you are using the pixhawk 2.4.8?
Why not just buy one with multiple already installed?
That would be far more expensive and I would need to rewire everything
The second imu also adds more ekf features and a full second independent lane that could improve safety of the quad since I would sometimes fly in little crowded areas so safety is very important
What kind of safety you think to add by the second, third, fourth imu?
Do you have noticed failures of your imu? The risk to have failures on external connected devices is much higher than onboard failures.
If safety is actually a priority, you’d replace the autopilot with one that isn’t a junk clone.
Simply tacking on another bit of cheap silicon is nothing more than a false sense of security.
Even then I do not think it will be any upgrade for this use case as I have found mine to be good enough.
@Ishitbh If you mean you fly in manual modes, I don’t think a second IMU is helpful at all. The MPU6000 is solid enough and I have have never experienced any drift with this sensor to cause a flyaway. If you use are using autonomous modes, most flyaways happen due to factors other than the onboard IMU such as very high vibrations (mechanical issue that is causing the IMU variance) or GPS glitches. If you think the drone is about to flyaway, you can switch into a manual mode. I would also personally prefer to have a switch set to Disarm (so that I can disarm immediately during flight) if safety is absolutely critical.
It is recommended to use Arm/Motor Emergency Stop (3Pos) or Motor Emergency Stop (2 Pos) to stop the motors in emergency as accidental activation of disarm switch is unrecoverable (successful rearming in freefall is like winning a lottery). Motor emergency stop disarms after some a few seconds.
What I have is rudder to the left plus a momentary switch. This causes Motor Emergency Stop. The only use for this is to prevent prop damage if things go wrong during setup phase. Can’t really imagine a flyaway scenario…
Actually the thing is that there is a competition and it is like sort of drone race but recently the changed the criteria and it now requires redundant primary sensors. So stabilize primarily uses imu so this imu has to redundant. Similarly if use althold then baro needs to be redundant. I don’t know why they have added this but I need to comply to fly in it
So if I need to add another sensor so I thought I should just add a sensor that would be better and not just another old sensor
Do they require fail-safe propulsion system? I would ask about the risk assessment that justifies such requirement as in my experience propulsion failures are much more common than sensor failures.