How to control motor movements and throttle using Arduino IDE, MAVLink, and Pixhawk

MAVLink
1

Hello everyone,

I am implementing the connectivity between the Pixhawk(2.4.8) and webapp. Please find the project setup information below,

Setup details :

  1. pixhawk 2.4.8
  2. ESP 8266
  3. M8N gps
  4. 2 wheel with motor
  5. R8FM Radio link to control motors
  6. Battery (2200mAh)

Development Tool:

I Using “Arduino IDE” tool to write code in ESP8266.

Installed Libraries:

  1. MAVLink.h
  2. Arduino.h

Setup Image:

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image1920×2560 428 KB

image
image1920×1440 151 KB

By using the above setup, I can arm & disarm and control left and right motors using Joystick controller.

QGC Connection:

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image1919×1008 84 KB

What we trying to do?

Here instead of Joystick we trying to control the project setup via web app. I established the connection between Pixhawk and server via webscoket (for data transfer between server and project setup). I can able to get the device info (GPS, motor and battery info) to webserver via custom code written in ESP 8266.

Problem Facing:

Same like, we trying to give input to arm & disarm and to control left and right motors. From the code written in ESP8266, cmd given to arm & disarm is working

CMD to arm and disarm:

arm command :
mavlink_msg_command_long_pack(
255, // System ID
190, // Component ID
&msg, // MAVLink message
1, // Target system ID (Pixhawk)
0, // Target component ID (all components)
MAV_CMD_COMPONENT_ARM_DISARM, // Command ID
0, // Confirmation
1, 0, 0, 0, 0, 0, 0 // Parameters (1 to arm)
);

disarm command :
mavlink_msg_command_long_pack(
255, // System ID
190, // Component ID
&msg, // MAVLink message
1, // Target system ID (Pixhawk)
0, // Target component ID (all components)
MAV_CMD_COMPONENT_ARM_DISARM, // Command ID
0, // Confirmation
0, 0, 0, 0, 0, 0, 0 // Parameters (0 to disarm)
);

but the cmd to control the left and right motors are not accepted by the kit.

CMD to run motors:

mavlink_msg_command_long_pack(
	255, 190, &msg,
	1, 0,
	MAV_CMD_DO_CHANGE_SPEED,
	0,
	MAV_MODE_FLAG_CUSTOM_MODE_ENABLED, MAV_MODE_MANUAL_ARMED, throttle, 0, 0, 0, 0
);

Please find the QGC logs:

I checked the QGroundControl (QGC) logs, which only show ‘arm’ and ‘disarm’ logs. There are no throttle or other command logs.

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Questions:

  1. Can you confirm my libraries are correct ?
  2. What are the mavlink commands to control left and right motors ? - to spin front and back
  3. Is there is any alternative libraries to control whole devices ?
  4. Is there is any existing solution to control pixhawk and its connected device via web ?
2

Are you using PX4 or MissionPlanner?

This doesn’t look right. It’s not made for motor speeds but for a vehicle’s speed.

Instead, with PX4 you would use MAV_CMD_DO_SET_ACTUATOR.

3

hi @JulianOes ,

We have tried this command earlier. The problem we faced while running this command was that, it only worked while the QGC(QGroundControl) was running in the background. When the QGC was closed, all it did was make beep sounds (& the motors did not work). How can I find a solution to this problem?

4

You didn’t even answer my question.