There are many things I love about the KK2.1 flight control board including its small and light form factor, the ease with which it can be configured, its versatility, and its self-level feature, which is the subject of this step. When in self-level mode, the KK2.1, as you can probably guess, attempts to keep the quadcopter as level as possible during flight. Self-level is a great feature for people who are new to flying quadcopters as it greatly reduces the chance of losing control and crashing. Flying in self-level mode is also nice for doing aerial photography or videography since it makes the quadcopter a nice, stable platform for your camera.
But, for the self-level feature to work well, we are going to need to customize some settings for the SK450 Dead Cat quadcopter. Fortunately, this step does not require much explanation because what we will actually be doing is calibrating another PID loop like we did in the last step, just this time the PID loop is used for a different purpose.
Just before we conclude this step, I wanted to include one final bit of theory about the ACC Trim Pitch value. The reason we decreased that value from 0 to -3 has to do with the geometry of our SK450 Dead Cat quadcopter. The difference between a normal X quadcopter and our SK450 Dead Cat quadcopter is in the position of Motor One and Motor Two. Compared with a normal quadcopter, the front arms of our Dead Cat quadcopter are angled back by 25o. The negative ACC Trim Pitch value helps prevent the quadcopter from tipping forward since, relative to a normal quadcopter, there is less lift for the front of the craft. If you mount a heavy camera in the front, you may wish to decrease this value a bit further.
- P Gain: 42
- P Limit: 56
- ACC Trim Roll: 0
- ACC Trim Pitch: -3