Issue with uORB message TrajectorySetponit

Adam_Brown · May 11, 2023, 4:25pm

I am using Uorb messages with ROS2 to make a drone move in gazebo simulation. I am using Trajectoy setpoint to make the drone go up at a certain velocity. However when I assign the velocity it goes to a certain height which is similar to the velocity value I assigned and then just stops going up. Its as if its taking the velocity value as a position value instead. I used a script made by px4 as a template.
Am I using the wrong uORB message?
link to script below:

github.com

adamongerfoo/px4code/blob/650cf03aa21f24247e44c99256a26af7cccc0ca8/verticalvel.py



import time
import rclpy
from rclpy.node import Node
from rclpy.clock import Clock

from px4_msgs.msg import OffboardControlMode
from px4_msgs.msg import TrajectorySetpoint
from px4_msgs.msg import VehicleCommand
from px4_msgs.msg import VehicleControlMode
from px4_msgs.msg import VehicleThrustSetpoint
from px4_msgs.msg import TrajectoryWaypoint
from px4_msgs.msg import VehicleOdometry



class test1(Node):

    def __init__(self):

This file has been truncated. show original

Benja · May 12, 2023, 3:07am

Hi @Adam_Brown , if you take a look at the offboard mode documentation you will see that to track a velocity reference you must set position field of the trajectorySetpoint message to NaN. Any other finite value will switch on the position controller. So right now you are asking your drone to go to position 0 0 0 with feedforward velocity [0.0, 0.0, -2.0]. The equilibrium of this is exactly what you are seeing. See also Offboard mode set velocity not working - #2 by Benja

FYI @hamishwillee , I think the offboard mode doc should be better linked to the ROS 2 guide and reshaped a bit to have the different control modes better explained.

hamishwillee · May 12, 2023, 4:22am

FYI @hamishwillee , I think the offboard mode doc should be better linked to the ROS 2 guide and reshaped a bit to have the different control modes better explained.

I’ve tried to keep that doc “abstracted” from implementations. But you’re right. Let’s talk about it next week.