search

PX4 / PX4-Autopilot

PX4 Autopilot Software
https://px4.io
BSD 3-Clause "New" or "Revised" License
8.47k stars 13.5k forks source link

use param for disarmed value of ESCs connected via CAN #20081

Open FlorianPix opened 2 years ago

FlorianPix commented 2 years ago

Describe problem solved by the proposed feature

in v1.13 PX4-Autopilot/src/drivers/uavcan/actuators/esc.cpp line 91 is responsible for setting the disarmed value that gets published to the ESCs over CAN. The value is hardcoded to 0 but some ESCs don't idle at 0. For example my ESCs spin backwards with full power at 0.

Describe your preferred solution

Use a param like PWM_MAIN_DIS to configure the CAN ESCs disarmed value.

FlorianPix commented 2 years ago

just adding disarmed: { min: 0, max: 8191, default: 4096 } above these lines isn't enough. That adds the parameters but they aren't used then to actually change the value used by uavcan.

FlorianPix commented 2 years ago

because the param didn't exist before it was set in uavcan_main.cpp and thereby invalidated afterwards

FlorianPix commented 2 years ago

I still need to investigate why uavcan only reacts to actuator_motors and actuator_servo commands between 0 and 1 (leading to output 4096 and 8191). Because I need it to react to -1 till 0 (0 till 4096) as well.

EDIT: adding reversible_flags 255 to the actuator_motors/servos messages helped

FlorianPix commented 2 years ago

As stated in dronecan the usual range for CAN ESCs is -8191 to 8191. The ESCs im using might just not comply to the standard. One could still add the parameters with range -4096 to 4096 and set the default to 0.

bkueng commented 2 years ago

Yes you need to remove this line as well if you want it to be confiurable: https://github.com/PX4/PX4-Autopilot/blob/main/src/drivers/uavcan/uavcan_main.cpp#L577 But I'd much rather have the ESC conform to the standard. Can you ask the manufacturer?

You can configure motors to be bidirectional in the UI: https://docs.px4.io/main/en/config/actuators.html

TorbjornHouge commented 1 year ago

I would also prefer to have a UAVCAN_EC_DISx parameter like PWM_MAIN_DISx, and the option of outputting this upon pre-arm like the PWM-ports do. Currently, since my ESCs expect to be fed a zero-value (pwm 1000 or equal) they will not arm until I perform an ARM-DISARM-sequence. Upon the next ARM they will go to the idle-speed set in UAVCAN_EC_MINx. I can set this value to 1 in order to make them arm at the appropriate time, but that will not give me idle-speed when arming and it will then make the throttle response more jumpy in manual/stabilize.