Discussions

I just upgraded my tricopter from 3.2.1 to 3.3 and got bit by the reversed servo bug. As those of you with tricopters know, there has been a variable called RC7_REV which you can use to ensure the APM/Pixhawk moves the tail servo in the correct direction. It default loads as +1, but I've often had to change it to -1. I know to do this because the tricopter spins wildly out of control as soon as it lifts off.

I knew 3.3 introduced a new variable called MOT_YAW_SV_REV to replace the reversing done by the RC7 variable. What I didn't expect was that the new variable loads a +1 as its default. So......liftoff of what had been an extremely  well behaved tri turned into a whirling dervish. I got it back on the ground with minimal damage and after a bit of research discovered I needed to change the MOT_YAW_SV_REV to -1 to match the -1 of my older RC7_REV. So that's OK now, but be careful when upgrading if your RC7_REV is -1.

Putting aside the initial spinning, I can't say I'm thrilled with 3.3 on my tricopter at this point. Under 3.2.1 I had the yaw pretty well dialed in using a high Stabilize Yaw value. But with 3.3 the yaw is really sloppy and wants to drift. Doesn't lock like it used to. I've imported and used the same PIDs as the older firmware so I'm surprised at the change in its handling. Clearly I'm going to have to do a bit of messing around to get back my earlier performance.