I built a tricopter based on the titan frame, APM2.6, TGY-390DHM servo.
http://www.fortisairframes.com/titan-tricopter-frame-kit/
First, the servo was the correct direction when using the controller but the APM corrected the wrong way, causing it to spin.
Not reading the directions, i then reversed RC4, and then the APM held yaw properly, but the controller was now reversed. so i reversed the controller and everything now works.
So i had to rev RC4 and rev channel 4 on my TX.
The question came up when i read the directions and it states to reverse RC7. Why is that? i know the servo is connected to output 7, but i thought RCx were the input channels?
Did i fix it the improper way? If i rev RC7 will that not mess with channel 7 options? Why did i need to rev rc4 and channel 4 on my tx to fix the servo operation?
Replies
Your description isn't really clear on how you've hooked up your system. Unless you do APM remapping, output 1 is the front right motor, output 2 is the front left motor, output 4 is the rear motor and output 7 is the yaw servo. I think you mighty be confusing your input RC channels with the output channels. The channel 7 options apply only to the input side.
Depending on the specific brand of servo and the way it's mounted, you may have to reverse RC7 in the APM and/or your RC transmitter's yaw output. You might have to reverse both, or only one. You won't really know until you start testing. The RC transmitter is easiest, as you can see how it tilts the yaw servo (Note that you are NOT reversing the channel 7 RC output, you are reversing the yaw channel!!). But you won't know whether or not to reverse RC7 in the APM until you just try and hover and see if it spins.
Thanks, i think my confusion is the way things are labeled. The instructions refer to the outputs as "RC1-8" and mission planer/firmware labeled the inputs RC1-xx.
This line here caused the confusion:
(*Tricopter note: If the direction of your tail servo is going the wrong way in response to yaw then set RC7_REV to -1 (from 1), you may also need to then reverse your transmitter rudder channel as well.)
on this page: connecting-your-rc-input-and-motors
My setup uses " stock" input channel settings and motor outputs. (channel 4 is yaw)
Thanks for clearing that up. I guess in this case reading the instructions only confused things :)
Confusion is understandable. tricopters are funky to start with, then there's the problem of possibly having to do reversals of the yaw servo....or not. I usually don't attempt a full liftoff to check the correctness of the APM. That could end up badly. I just barely start it to lift and see if it starts to rotate on me. If it does, then I know to reverse the APM's output for RC7.