Anybody with experience in APM Tri copters? I’m sure this has been asked before, but I really need to get this thing off the ground.
I’m set to go except one thing. My Tri Copter has no yaw servo movement. The signal seems to have no pass through. The motors spin up with the throttle, and adjust in different attitudes, but no tail servo. I have no where to begin, and need suggestions.
It has power supplied from a separate step-down converter to the tail servo, and retracts. I am running an FRSKY module in a futaba 9C with a FRSKY D8R-XP in CPPM mode.
The radio calibrates, and all the green bars move through Ch 8, there are no warnings at all.
Is there a way to check the firmware while connected to make sure it is tri copter firmware?
It seems that when you select the frame type in MP, the tri copter frame is mixed with a whole bunch of others kind of generally…
I am suspecting that the tri copter firmware is not going into my board, which might explain no tail servo movement. (maybe)
Tail servo plugged into ch7 on receiver. The motors arm, I have no warnings.
I found this on the APM Tricopter wiki, but it seems it is a bit vague. I believe this page is the issue.
I wish there were clear, concise directions to solve this problem on the wiki. It seems that this problem has been over looked, or most likely people like Quads, and other frame types better. No biggie, I like Tricopters for their maneuverability.
I suspect these settings are in the advanced parameters…
Can you make sense of them? If so can you explain it to me?
MOT_YAW_SV_MIN: yaw servo’s lowest PWM value before binding occurs.
MOT_YAW_SV_MAX: yaw servo’s highest PWM value before binding occurs.
MOT_YAW_SV_TRIM: yaw servo’s PWM value close to what is required to keep the tail from spinning.
MOT_YAW_SV_REV: yaw servo’s reverse setting. +1 = servo moves in default direction, -1 to reverse direction of movement.
Copter 3.2.1 (and earlier)
RC7_MIN: yaw servo’s lowest PWM value before binding occurs.
RC7_MAX: yaw servo’s highest PWM value before binding occurs.
RC7_TRIM: yaw servo’s PWM value close to what is required to keep the tail from spinning.
RC7_REV: yaw servo’s reverse setting. +1 = servo moves in default direction, -1 to reverse direction of movement.
I’m using 3.2.1 on my tricopter and have been for quite a while now and have had no issues, the only thing I had to do was reverse the tail servo by setting RC7_REV to -1. I haven’t tried 3.3 yet, waiting for the issues to be sorted out first.
Forgot also to say that the tail servo also only works when the system is armed (motors spinning) AND the throttle is above zero (take the props off).
When I set everything up it just worked so not sure what’s happening with your Tricopter.
As for settings, here’s a rough guide:
RC7_MIN: = 1100
RC7_MAX: = 1900
RC7_TRIM: = 1500
RC7_REV: -1 or 1
You can set the min/max to higher or lower depending on how much servo movement you want or need, the range is 900-2100 which is what most servo’s can handle.
Set the EPA on your Tx to 100%/100%.
You can monitor the input and output of RC7 in the status window of mission planner.
If you are seeing the green bar move for channel 7 in Mission Planner then you most likely either have a bad servo or the way you’ve provided power to the servo is incorrect (floating ground perhaps).
Also, you posted that, “Tail servo plugged into ch7 on receiver”. I hope you mean the servo is plugged into output 7 of the Pixhawk.
Hello Gentlemen, thank you for responding.
Yes, I thought about the floating ground issue, but it is grounded to the lipo battery itself, via the balance plug. I do not think there is a better ground
I am going to mess with RC_7, and start with Grahams settings as a start point. For some reason it is probably nulled, even though I have Tri copter firmware loaded. I will probably have to do the same with RC_5 as this is where I have the retracts hooked to.
When I first powered it up the servo did move to a neutral position, but I am going to test the servo again anyway.
I am slowly narrowing in on the problem, and can’t wait to fly this thing. I have two more in the works. A Hobbyking C-3, and an RC Explorer with some secret mods that will make it super fast…
Sure I could just put a flip Mega 3.5 board in this one, but then that would be giving up.
Problem Solved, A simple bad intermittent connection, in two places. That is why it was baffling.
No problem in RC-7, I just have to make sure things move correctly, and the tilt is at 5 degrees.
I wired it correctly after all of my self doubt
Thank you for your support gentlemen.
