Mission Transfer Failed With Hover And Capture Option Set In Survey Mission.

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Introduction

When setting the "Hover and Capture" option in a survey mission, users expect the mission to transfer to the copter seamlessly. However, a pop-up error message appears, indicating that the mission transfer failed due to an invalid parameter value. In this article, we will delve into the expected behavior, current behavior, system information, and detailed description of the issue to identify the root cause and provide a solution.

Expected Behavior

The mission should transfer to the copter when the "Hover and Capture" option is set. This option is designed to enable the copter to capture images while hovering over a specific area. The expected behavior is that the mission will execute smoothly, and the copter will capture images as intended.

Current Behavior

When the "Hover and Capture" option is set, a pop-up error message appears, indicating that the mission transfer failed. The error message reads:

Mission transfer failed. Error: Param 4 invalid value. Item #4 Command: Start image capture Value: nan

This error message suggests that there is an issue with the fourth parameter of the "Start image capture" command. The value of this parameter is set to "nan" (Not a Number), which is causing the mission transfer to fail.

System Information

To better understand the issue, we need to gather information about the system configuration. The following details are provided:

  • Operating System: Pop!_OS 22.04
  • QGC Version: 4.3.0
  • QGC build: Flatpak
  • Flight Controller: Pixhawk 6c
  • Autopilot (with version): Ardupilot Copter 4.5.7

Detailed Description

To further investigate the issue, we need to examine the .plan file, which contains the mission plan. The .plan file is a JSON file that defines the mission parameters. The relevant section of the .plan file is:

{
    "autoContinue": true,
    "command": 2000,
    "doJumpId": 4,
    "frame": 2,
    "params": [
        0,
        0,
        1,
        null,
        null,
        null,
        null
    ],
    "type": "SimpleItem"
},

As we can see, the fourth parameter of the "Start image capture" command is set to null. This is likely the cause of the error message.

MavLink Docs

To confirm our suspicions, we need to consult the MavLink documentation. The MavLink documentation provides information about the MAV_CMD_IMAGE_START_CAPTURE command, which is used to start image capture. According to the documentation, the fourth parameter of this command should be set to either 0 or 1.

Solution

To resolve the issue, we need to modify the fourth parameter of the "Start image capture" command to either 0 or 1. This can be done by manually editing the .plan file. Once the parameter is set to a valid value, the mission should upload successfully.

Conclusion

In conclusion, the mission transfer failed with the "Hover and Capture" option set in the survey mission due to an invalid parameter value. The error message indicated that the fourth parameter of the "Start image capture" command was set to "nan". By examining the .plan file and consulting the MavLink documentation, we were able to identify the root cause of the issue and provide a solution. By setting the fourth parameter to a valid value, the mission should transfer to the copter seamlessly, and the copter should capture images as intended.

Troubleshooting Tips

If you encounter a similar issue, here are some troubleshooting tips to help you resolve the problem:

  1. Examine the .plan file: Check the .plan file to see if the fourth parameter of the "Start image capture" command is set to a valid value.
  2. Consult the MavLink documentation: Consult the MavLink documentation to confirm the expected value of the fourth parameter.
  3. Manually edit the .plan file: Manually edit the .plan file to set the fourth parameter to a valid value.
  4. Upload the mission again: Once the parameter is set to a valid value, upload the mission again to see if the issue is resolved.

Introduction

In our previous article, we discussed the issue of mission transfer failure with the "Hover and Capture" option set in a survey mission. We identified the root cause of the issue and provided a solution. In this article, we will answer some frequently asked questions (FAQs) related to this issue.

Q: What is the expected behavior of the "Hover and Capture" option in a survey mission?

A: The expected behavior of the "Hover and Capture" option in a survey mission is that the mission should transfer to the copter seamlessly, and the copter should capture images as intended.

Q: What is the current behavior of the "Hover and Capture" option in a survey mission?

A: The current behavior of the "Hover and Capture" option in a survey mission is that a pop-up error message appears, indicating that the mission transfer failed due to an invalid parameter value.

Q: What is the error message that appears when the mission transfer fails?

A: The error message that appears when the mission transfer fails is:

Mission transfer failed. Error: Param 4 invalid value. Item #4 Command: Start image capture Value: nan

Q: What is the root cause of the issue?

A: The root cause of the issue is that the fourth parameter of the "Start image capture" command is set to "nan" (Not a Number) in the .plan file.

Q: How can I resolve the issue?

A: To resolve the issue, you need to modify the fourth parameter of the "Start image capture" command to either 0 or 1 in the .plan file.

Q: What is the MavLink documentation, and how can it help me resolve the issue?

A: The MavLink documentation is a resource that provides information about the MAV_CMD_IMAGE_START_CAPTURE command, which is used to start image capture. By consulting the MavLink documentation, you can confirm the expected value of the fourth parameter and resolve the issue.

Q: What are some troubleshooting tips that I can use to resolve the issue?

A: Here are some troubleshooting tips that you can use to resolve the issue:

  1. Examine the .plan file: Check the .plan file to see if the fourth parameter of the "Start image capture" command is set to a valid value.
  2. Consult the MavLink documentation: Consult the MavLink documentation to confirm the expected value of the fourth parameter.
  3. Manually edit the .plan file: Manually edit the .plan file to set the fourth parameter to a valid value.
  4. Upload the mission again: Once the parameter is set to a valid value, upload the mission again to see if the issue is resolved.

Q: Can I use a different value for the fourth parameter of the "Start image capture" command?

A: Yes, you can use a different value for the fourth parameter of the "Start image capture" command. However, you need to consult the MavLink documentation to confirm that the value you choose is valid.

Q: How can I prevent this issue from occurring in the future?

A: To prevent this issue from occurring in the future, you can:

  1. Double-check the .plan file: Before uploading the mission, double-check the .plan file to ensure that the fourth parameter of the "Start image capture" command is set to a valid value.
  2. Consult the MavLink documentation: Consult the MavLink documentation to confirm the expected value of the fourth parameter.
  3. Use a valid value for the fourth parameter: Use a valid value for the fourth parameter of the "Start image capture" command.

By following these troubleshooting tips and best practices, you can resolve the issue and prevent it from occurring in the future.