Value Meaning
0 Don’t adjust the trims
1 Assume first orientation was level
2 Assume ACC_BODYFIX is perfectly aligned to the vehicle

Looking for advice on the right setting for this parameter. The default seems to be 1. But there isn’t really an explanation of what the two options mean. Assume what first orientation? Power up? Arming? Accel cal? Would 2 be better for a non isolated IMU since it is showing actually frame state?

I have ACC_BODYFIX set to IMU3 since that is the one that isn’t vibration isolated.

Hi Matt,

I’m not an expert in this area, so I’m not sure of the relevance of this parameter. All I can say after looking at code:

From accel cal. Accel calibration gives you steps to change your vehicle position to, but in reality it doesn’t care if you follow them, as long as the samples have enough difference between them. But the trim does need to know what is level, so option 1 assumes you did the correct thing and your first accel calibration sample is level.

I’m assuming that comparing the samples from isolated IMUs against the one that isn’t gives a better trim (it still assumes the first accel cal sample is level position). In reality this was ported from Solo and I’m not sure the current approach is generic enough.

In 3DR’s branch there’s no option, so I guess that for Solo parameters, you want this to set to 2 (as well as ACC_BODYFIX set to 2 3).

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Received. I will set it for 2, run the accel and level calibrations again, and test fly. Phillip said 1 & 2 are the isolated IMUs, making #3 the body fixed IMU,

Yes, sorry, just changed that. I’m not sure why the default is 2, probably a mistake when porting from Solo fork to master.

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