uable to use MAV_CMD_DO_SET_SERVO

[KBhanup]

I am trying to use MAV_CMD_DO_SET_SERVO to send PWM commands to AUX1 (channel 9). But unable to find the right protocol structure to do it. Aim: I want to integrate activating and Deactivating magnet into a FCU code that I have built (set Magnet at AUX1 normally operated through RC)

msg_hi = self.vehicle.message_factory.command_long_encode( 0, 0, # target_system, target_command mavutil.mavlink.MAV_CMD_DO_SET_SERVO, # command 0, 8, # servo number 2006, # servo position 0, 0, 0, 0, 0)

Here, I know here in this example I have tried using similar dronekit function not knowing how I can do using MAVSDK or MAVROS, Pleaseee guide me if any alternative ways how I can do it?

I don't see my drone responding even after sending self.vehicle.send_mavlink(msg_hi), checked the AUX1 pin with Oscilloscope, but I don't see any fluctuating signal..

I am using Px4 and Odroid as my onboard computer..

%%

!/usr/bin/python

import rospy as rp import threading

from dronekit import connect, VehicleMode from pymavlink import mavutil

from std_msgs.msg import Int8 from sensor_msgs.msg import Joy from geometry_msgs.msg import PoseStamped, TwistStamped

class magdroneControlNode():

def __init__(self):
    rp.init_node("magdrone_deploy")

    # Connect to the Vehicle
    rp.loginfo('Connecting to Vehicle')
    self.vehicle = connect('/dev/ttyUSB0', wait_ready=True, baud=921600)

    # Set up Subscribers
    self.joy_sub = rp.Subscriber("/joy", Joy, self.joy_callback, queue_size=1)

    # Create thread for publishers
    self.rate = 30
    t = threading.Thread(target=self.send_commands)
    t.start()

    rp.spin()

def joy_callback(self, data):
    # Button Controls
    if data.buttons[0] == 1.0:
        rp.loginfo("Mission set to 1 - Deploying Sensor")
        self.mission_id = 1

    if data.buttons[1] == 1.0:
        rp.loginfo("Mission set to 2 - Retrieving Sensor and Exiting")
        self.mission_id = 2

'''
    Magnet Control
'''

def engage_magnet(self):
    msg_hi = self.vehicle.message_factory.command_long_encode(
            0, 0,   # target_system, target_command
            mavutil.mavlink.MAV_CMD_DO_SET_SERVO, # command
            0,
            8,    # servo number
            2006, # servo position
            0, 0, 0, 0, 0)

    msg_neut = self.vehicle.message_factory.command_long_encode(
            0, 0,   # target_system, target_command
            mavutil.mavlink.MAV_CMD_DO_SET_SERVO, # command
            0,
            8,    # servo number
            1500, # servo position
            0, 0, 0, 0, 0)

    # Send command
    self.vehicle.send_mavlink(msg_hi)
    rp.loginfo("Magnet Engaged")
    time.sleep(5)
    self.vehicle.send_mavlink(msg_neut)
    rp.loginfo("Magnet in Neutral")
    self.docked = True

def disengage_magnet(self):
    msg_low = self.vehicle.message_factory.command_long_encode(
            0, 0,   # target_system, target_command
            mavutil.mavlink.MAV_CMD_DO_SET_SERVO, # command
            0,
            8,    # servo number
            982,  # servo position
            0, 0, 0, 0, 0)

    msg_neut = self.vehicle.message_factory.command_long_encode(
            0, 0,   # target_system, target_command
            mavutil.mavlink.MAV_CMD_DO_SET_SERVO, # command
            0,
            8,    # servo number
            1500, # servo position
            0, 0, 0, 0, 0)

    # Send command
    self.vehicle.send_mavlink(msg_low)
    rp.loginfo("Magnet Disengaged")
    time.sleep(5)
    self.vehicle.send_mavlink(msg_neut)
    rp.loginfo("Magnet in Neutral")
    self.docked = False

'''
    Main Loop
'''

def send_commands(self):
    rp.loginfo("Accepting Commands")
    r = rp.Rate(self.rate)
    while not rp.is_shutdown():   

        if (self.mission_id == 1) & (not self.magnet_engaged):
            self.magnet_engaged = True
            t = threading.Thread(target=self.engage_magnet)
            t.start()

        if (self.mission_id == 2) & (self.magnet_engaged):
            self.magnet_engaged = False
            t = threading.Thread(target=self.disengage_magnet)
            t.start()
        r.sleep()

Start Node

magdrone = magdroneControlNode()

[JonasVautherin]

I am not familiar with MAV_CMD_DO_SET_SERVO. Is it similar to MAVSDK's SetActuator action?

[julianoes]

It looks like this is a PX4 question and not a MAVSDK question. Also your example code is DroneKit or pymavlink and not MAVSDK, so not sure what to do with it.