Offboard Mode - MAVSDK - Drone random movement

Jetson Nano

I'm using a setup consisting of,

Flight Controller: Flight Core V2
Comapanion: VOXL2
PX4 version: PX4 1.14.3 dev version (modalai fork)

I'm able to connect and communicate between FC and Flight controller through the UART ports. Also initialise the mavlink stream from one of the ports on FC to initiate streaming of mavlink messages.

mavlink stream -r 30 -s ODOMETRY -d /dev/ttyS6

In voxl-vision-hub, I have defined the offboard mode to trajectory. When shifting to offboard, the drone stays at position since I'm streaming the mavlink message as stated above. The drone hovers stable in the same position(there are no visible drift or random motion which could be observed)

I have built MAVSDK on VOXL2 and try to execute a python script consisting of a path.

Below is the script,

#!/usr/bin/env python3

"""
Caveat when attempting to run the examples in non-gps environments:

`drone.offboard.stop()` will return a `COMMAND_DENIED` result because it
requires a mode switch to HOLD, something that is currently not supported in a
non-gps environment.
"""

import asyncio

from mavsdk import System
from mavsdk.offboard import (OffboardError, PositionNedYaw)


async def run():
    """ Does Offboard control using position NED coordinates. """

    drone = System()
    await drone.connect(system_address="serial:///dev/ttyHS1:2000000")

    print("Waiting for drone to connect...")
    async for state in drone.core.connection_state():
        if state.is_connected:
            print(f"-- Connected to drone!")
            break

    print("-- Arming")
    await drone.action.arm()

    print("-- Setting initial setpoint")
    await drone.offboard.set_position_ned(PositionNedYaw(0.0, 0.0, 0.0, 0.0))

    print("-- Starting offboard")
    try:
        await drone.offboard.start()
    except OffboardError as error:
        print(f"Starting offboard mode failed \
                with error code: {error._result.result}")
        print("-- Disarming")
        await drone.action.disarm()
        return

    print("-- Go 0m North, 0m East, -1m Down \
            within local coordinate system")
    await drone.offboard.set_position_ned(
            PositionNedYaw(0.0, 0.0, -1.0, 0.0))
    await asyncio.sleep(3)

    print("-- Go 1m North, 0m East, -1m Down \
            within local coordinate system, turn to face East")
    await drone.offboard.set_position_ned(
            PositionNedYaw(4.4, 0.0, -1.0, 0.0))
    await asyncio.sleep(7)

    print("-- Go 1m North, 0m East, -1m Down \
            within local coordinate system, turn to face East")
    await drone.offboard.set_position_ned(
            PositionNedYaw(4.4, 0.0, -1.0, 90.0))
    await asyncio.sleep(4)

    print("-- Go 1m North, 1m East, -1m Down \
            within local coordinate system")
    await drone.offboard.set_position_ned(
            PositionNedYaw(4.45, 2.9, -1.0, 90.0))
    await asyncio.sleep(5)

    print("-- Go 0m North, 1m East, -1m Down \
            within local coordinate system, turn to face South")
    await drone.offboard.set_position_ned(
            PositionNedYaw(5.9, 5.0, -1.0, 30.0))
    await asyncio.sleep(8)
    
    print("-- Go 0m North, 0m East, -1m Down \
            within local coordinate system, turn to face South")
    await drone.offboard.set_position_ned(
            PositionNedYaw(10.1, 4.8, -1.0, 0))
    await asyncio.sleep(6)
    
    print("-- Go 0m North, 0m East, 0m Down \
            within local coordinate system, turn to face South")
    await drone.offboard.set_position_ned(
            PositionNedYaw(11.9, 6.6, -1.0, 45))
    await asyncio.sleep(4)

    print("-- Go 0m North, 0m East, 0m Down \
            within local coordinate system, turn to face South")
    await drone.offboard.set_position_ned(
            PositionNedYaw(11.9, 6.6, -1.0, 90))
    await asyncio.sleep(2)

    print("-- Go 0m North, 0m East, 0m Down \
            within local coordinate system, turn to face South")
    await drone.offboard.set_position_ned(
            PositionNedYaw(12.3, 10.0, -1.0, 90.0))
    await asyncio.sleep(5)

    print("-- Go 0m North, 0m East, 0m Down \
            within local coordinate system, turn to face South")
    await drone.offboard.set_position_ned(
            PositionNedYaw(12.7, 13.0, -1.0, 90.0))
    await asyncio.sleep(5)

    print("-- Go 0m North, 0m East, 0m Down \
            within local coordinate system, turn to face South")
    await drone.offboard.set_position_ned(
            PositionNedYaw(12.7, 13.0, 0.3, 90.0))
    await asyncio.sleep(1)

    print("-- Stopping offboard")

    try:
        await drone.offboard.stop()
    except OffboardError as error:
        print(f"Stopping offboard mode failed \
                with error code: {error._result.result}")


if __name__ == "__main__":
    # Run the asyncio loop
    asyncio.run(run())

Once the above script is initialised once the drone is the air and shifted to offboard mode, the script is supposed to make the drone pass through a set of defined waypoints in NED frame.

When executing the above script I observe,

there is a random jittery motion in movement of the drone passing trying to reach further waypoints.
Visually I see that there is a resistance in the drone trying to move to next waypoints. Not sure if the drone is trying to come back to Home position.

How can I make the drone move through the defined waypoints?

Zachary Lowell 0

Why do you have it set to trajectory? If you are commanding the drone via strictly offboard commands programmatically - vision-hub should have offboard set to "off" so it isnt conflicting offboard commands with what you are feeding in.

Please do this and retest and post the results.

Jetson Nano

@Zachary-Lowell-0 as mentioned I have set offboard-mode in voxl-vision-hub.conf to "off".

I did a flight test shifting to offboard-mode,

The drone was able to execute the script in a stable way without any jittery motions or trying to come back to home position.

These are the flight logs,
https://review.px4.io/plot_app?log=e32a28df-cbba-4765-8499-6fe46e2ff890