I have TKOFF mode set on an RC switch, and with ground testing, everything seems to be working well. Two questions:
I’m fairly new to plane, but in my experience (and with my set parameters), when the FC is armed and I switch to takeoff mode, it will go to takeoff thrust regardless of whether I have the throttle stick at zero or any other position. ETA: If you can share a parameter file, I can take a look.
Yes, you would need to switch out of takeoff mode.
If you switch out of takeoff mode and are then in FBWA, you will need to move your throttle stick up to have thrust, or already have it at a position where the throttle will drop down to when you switch modes.
Me too
No. Is the plane armed when you switch to TKOFF?
When you flip the switch back, the mode you selected on the normal mode channel will be active. If you select a different mode while TKOFF is active, that mode will take effect immediately.
Rolf
Thanks, I will try to generate a log with another test (I set a low IDLE Throttle (10%) and shake to get it to go to my test max throttle (30%). If I preset my throttle to any amount >0 before I engage TKOFF switch, I can’t get it to activate even the IDLE throttle).
Regarding the termination of TKOFF, if I switch off TKOFF, does my flight mode default to FBWA?
Rolf, plane is definitely Armed prior to flipping TKOFF switch.
My sequence: Arm plane, turn off throttle cut switch, raise throttle 50%, switch on TKOFF mode. This seems to prevent even idle throttle from starting.
As @Rolf mentioned, the flight mode will revert back to whatever you have selected on your flight mode channel.
t would be best if you could post a link to the *.bin file so we can take a closer look at it. It should actually work, especially since I run it the same way.
In testing to create the log file, I figured out the issue. It had to do with a safety throttle over-ride switch I have in addition to the ARM switch. Interestingly, TKOFF ignores this throttle over-ride (throttle cut) and will work normally with it off. If the throttle override switch is set to throttle enable, obviously I cannot advance the throttle prior to setting TKOFF because the motors will spin.
So, looks like I have to remember to arm the throttle AND advance the throttle before the plane goes into FBWA mode.
To create the log file: It’s best if you temporarily set LOG_DISARMED to 1 then logging will be enabled at all times, including when disarmed.
Rolf
How are you doing the throttle cut? I’m guessing it’s in the radio. I’d argue that with a flight controller in the loop managing the arming sequence, and all the arming checks are in place, a throttle cut isn’t needed and may in-fact be confusing things. Motor emergency stop is a switch function that is in Ardupilot that may give you the safety feature you’re looking for without extra complexity.
Is this plane gas or electric?
Allister, this plane is an electric twin, the ZOHD Altus, and yes, my throttle cut switch is a Special Function override of the throttle in EdgeTx.
I understand that there are other checks on throttle status, such as in EdgeTx when you turn the transmitter on, and in the Arduplane PreArm checks. Are you suggesting there are any other throttle checks that do not involve a physical switch.
My override switch is redundant, but I’ve seen or personally experienced accidents that occurred after successful arming. I guess it just gives me peace of mind. Maybe I could eliminate it on this hand-launched plane?
RC_OPTIONS bit 5 (should be on by default) will check that the throttle is down before arming. It’s confusing because the way it’s worded. In other words, ardupilot won’t let you arm unless the throttle is down, and all other arming checks have been passed (don’t disable any arming checks)
I’m a big proponent of RCx_OPTIONS, 165 #Arm/Emergency Stop This way I can arm with a switch but I can stop the motors right away if needed. More important with rotary wing than fixed wing, but it also doesn’t dis-arm right away even though the motors are stopped so if it happens in flight you can save it. (If the drone is motionless for a few seconds and the throttle is down it will disarm on it’s own. Usually by the time I’ve walked over and picked it up)
Can be different for gas engines, hence why I asked.
Thanks for expanding on the RC_Options and RCx_Options. The former was definitely set in my parameters. I was unaware of the RCx_Options 165. I’ll enable it and try it out, first on the ground. Hope I never trigger it by accident in the air!
Motor Emergency Stop is reversible so you can move the switch back to mid/high and the motor will be back on.
Good to know. There is also a RCx_OPTIONS = 31 that is also a motor stop function, but it is not clear from the description how it is different than the Emergency Motor Stop.
They’re the same. Just that the method I suggested has arming and motor stop on one switch. Option 31 was the original implementation of the feature and it was on it’s own switch, separate from arming.
OK, I think I get that, but I can be dense sometimes, how do you use the options 165? I just tried it on a separate switch with my plane. The motors will turn if either ARM has been done (using ARM switch) OR switch for Option 165 has been enabled…I thought it would stop the motors if the plane was armed…confused. Sorry!
165 does arming and motor stop on one switch. No need for two switches.
I use this system with post-secondary students and it’s been safe enough that everyone can still count to 10 and we’ve had no mid-flight disarms. Even if somebody bumps the switch you can flick it back in the air and recover. We did have issues with mid-flight disarming when we used a single arm/disarm switch.
Great explanation, thanks! I just tried it outside on a bench (no flight) and it works as you describe. One thing that differed was that the plane would not disarm after motors were stopped and I left the plane sit. I waited at least at minute. Any ideas why?
AFAIK disarming on motor emergency stop is copter only behavior. Plane generally will only disarm if it thinks it is landed (except for disarm and arm/disarm switches) and you command disarm.