Question regarding publishing motor speed to Gazebo & some theoretical parameters about crazys HOT 6 CLOSED

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from crazys.

Hi! Think of my 'answers' with a grain of salt, I am no expert regarding this repo. I am just someone who used this repo recently as well.

For Issue 1, you publish the motor speed to /crazyflie/command/motor_speed. I used the Matlab version of this repo, so I am not entirely sure how to publish
via script, but in Matlab, /crazyflie/command/motor_speed needs input from mav_msgs/Actuators and Propellers Angular Velocities (4) from Omegas (motor speed), see Fig. 11 (p.22) of the documentation that you refer to.
As for the units, I already forgot but I think it's in the docu as well.

As for Issue 2, I think it's correct as maybe the ones showed in Gazebo is rounded-up to 0.XX significant digits? Not entirely sure.

If you wait for a bit, your issues maybe resolved by the author of this repo, good luck!

from crazys.

Update for Issue 1 regarding the motor speed:

I found that the /CrazyS/src/CrazyFlie/rotors_control/src/nodes/roll_pitch_yawrate_thrust_crazyflie_node.cpp is also publishing some sort of motor speed commands to gazebo apart from the /crazyflie2/command/motor_speed one, what should we do about this? E.g. does these two node interfere each other during simulation in gazebo?

from crazys.

Hi! Think of my 'answers' with a grain of salt, I am no expert regarding this repo. I am just someone who used this repo recently as well.

For Issue 1, you publish the motor speed to /crazyflie/command/motor_speed. I used the Matlab version of this repo, so I am not entirely sure how to publish via script, but in Matlab, /crazyflie/command/motor_speed needs input from mav_msgs/Actuators and Propellers Angular Velocities (4) from Omegas (motor speed), see Fig. 11 (p.22) of the documentation that you refer to. As for the units, I already forgot but I think it's in the docu as well.

As for Issue 2, I think it's correct as maybe the ones showed in Gazebo is rounded-up to 0.XX significant digits? Not entirely sure.

If you wait for a bit, your issues maybe resolved by the author of this repo, good luck!

Hi! Thanks for the help!

For Issue 1, now I also agree with you that we should publish the motor speed to the /crazyflie2/command/motor_speed, but as my comments above mentioned, there is one more node named as /CrazyS/src/CrazyFlie/rotors_control/src/nodes/roll_pitch_yawrate_thrust_crazyflie_node.cpp that is also publishing something towards the same topic, so I am not sure how is this affect my result.

As for Issue 2, since the drone is too light-weighted (roughly 30 grams), so any small change in the value will result in a very huge change in the calculation result. Since I am trying to use pure math calculation to 'simulate' how the drone fly, so I think the numbers will be crucial to the result.

from crazys.

Hi wonggwan! Glad to hear from you that you found my work helpful. Here are my answers:

• Motor speeds are expressed in radians per second [rad/s]. If you want to control the drone, without using the provided controller, just run roslaunch rotors_gazebo crazyflie2_without_controller.launch. Then, your code should publish on the /crazyflie2/gazebo/command/motor_speed topic.

• ROS Messages are defined in the mav_msgs repository. Specifically, here you can find the definition of Actuators. You can find the maximum angular velocity in the the crazyflie2_base.xacro and crazyflie2_forster.xacro files. Since I have never tested the simulator with the Crazyflie, comparing the behaviors, I suggest you find your own parameters or rely on those in Forster's thesis.

I hope this helps. If not, let me know.

from crazys.

Hi wonggwan! Glad to hear from you that you found my work helpful. Here are my answers:

• Motor speeds are expressed in radians per second [rad/s]. If you want to control the drone, without using the provided controller, just run roslaunch rotors_gazebo crazyflie2_without_controller.launch. Then, your code should publish on the /crazyflie2/gazebo/command/motor_speed topic.
• ROS Messages are defined in the mav_msgs repository. Specifically, here you can find the definition of Actuators. You can find the maximum angular velocity in the the crazyflie2_base.xacro and crazyflie2_forster.xacro files. Since I have never tested the simulator with the Crazyflie, comparing the behaviors, I suggest you find your own parameters or rely on those in Forster's thesis.

I hope this helps. If not, let me know.

Thank you so much for your help! I think that solves my current problem! Closing this issue now:)

from crazys.