AIRBORNE PROJECTS DROTAG Sony Alpha Series Image Tagging User Guide

AIRBORNE PROJECTS DROTAG Sony Alpha Series Image Tagging

AIRBORNE PROJECTS

Airborne Projects specializes in building drone solutions with emphasis on telemetry gathering and integration with avionics and automatic flight systems.

DROTAG – Sony Alpha Series Image Tagging

DroTag is a small board that simply sits between your Sony Alpha Series camera and your Pixhawk, allowing you to plan the camera trigger events and have the pictures taken automatically geo-tagged on the fly.

Upon landing you only need to take out the card from your camera and the images are immediately available and ready to be visualized/used by your mapping software.

Product Usage Instructions

1. Install the DroTag board between your Sony Alpha Series camera and your Pixhawk.
   • For Sony Alpha Specifics, set the Tethering and Focus Mode settings as recommended in the manual.
   • Set up the TELEM Port Parameters, Arming mode (Arduplane specific), and Hot shoe configuration (optional) as instructed in the manual.
2. Plan your camera trigger events and set the time between pictures using the Preflight Mission Planning instructions.
3. Complete the Pre-Flight Checklist as detailed in the manual.
4. During flight, the DroTag board will automatically geo-tag each picture taken by your Sony Alpha Series camera.
   • Manual triggering from RC is available for ArduCopter only using the In Flight Capabilities instructions.
   • Do not take pictures while in RTL or LAND mission or mode as stated in the Flight Behaviour instructions.
5. After landing, remove the microSD card from your camera and access your pictures immediately for use with mapping software.
   • Follow the After Flight Capabilities instructions for DROTAG microSD card care.
   • If troubleshooting is needed, refer to the Troubleshooting section of the manual for solutions to common issues.

DroTag is a small board that simply sits between your Sony Alpha Series camera and your Pixhawk, allowing you to plan the camera trigger events and have the pictures taken automatically geo-tagged on the fly. Upon landing you only need to take out the card from your camera and the images are immediately available and ready to be visualized/used by your mapping software.

Context

This User Guide’s goal is to get DROTAG working with your tethering camera and your Ardupilot-based Flight Controller module. DROTAG is a small board that simply sits between your camera and your Flight Controller (like Pixhawk), allowing you to remotely trigger the camera (manual or automatically) and have the taken pictures auto- matically geo-tagged. The pictures are tagged in the camera itself. Currently, the main Sony cameras tested are (A5000, A5100, QX1, A6000, A6300, and RX100 M2), but others may be added in the future.

Assumptions

1. The DROTAG module is connected to one of the available telemetry output found on your flight controller (Pixhawk/NAVIO/etc);
2. The power to the DROTAG is supplied by the autopilot’s telemetry port;
3. To get the pictures geo-tagged you need a GPS fix on your Autopilot. Without it, DROTAG will not trigger the camera

Package Contents

1. DROTAG board;
2. New: External Flash Hotshoe PCB;
3. DROTAG Quick Start Guide;
4. An Operation Checklist;

Hardware installation

Below you can find a picture illustrating the installation. We point out that good practices are advised re- regarding the fixation of the board. Boards and Cables should be stowed clear of propellers in a vibration-resistant manner.

Sony Alpha Specifics
There are 2 camera settings DROTAG can’t change automatically, which are important for aerial photog- raphy. The tethering setting and the focus mode. In the following instructions, you will learn how to make these one-time configurations to your Sony camera. The procedure for each specific Sony camera can be slightly different steps than the one exemplified below.

Tethering setting

• Turn On the camera;
• Press the Menu button;
• Navigate to the Setup tile;
• Navigate-right, to page 2;
• On the USB Connection select USB Storage;

Focus Mode setting (Recommended)

• Turn On the camera;
• Press the Menu button;
• Select Camera Settings;
• Go to Page 3 by navigating right;
• Navigate and select Focus Mode;
• Navigate the options available until you find and select one saying MF;
• Rotate the lens ring until your camera says it is on 1.

Setup your TELEM Port Parameters

This step is required to configure the TELEMETRY Port that you are willing to use your DROTAG board. It only needs to be done once or any time you reset/refactor your parameters. In the following instructions, the SERIAL1 prefix corresponds to TELEM1. If you would like to use TELEM2 the applicable parameters are prefixed by SERIAL2. Accordingly, the prefix SERIAL4 corresponds to the physical port TELEM4/5.

1. Connect your Flight Controller to Mission Planner (or equivalent);
2. Select the Config/Tuning tab;
3. Select Full Parameter Tree;
4. Find the command node SERIAL1 and set:
   • SERIAL1_BAUD 57 – For sales or firmware before 2018/04/10.
   • SERIAL1_BAUD 115 – For sale of firmware after 2018/04/10.
   • SERIAL1_PROTOCOL 1
5. Click Write Params
6. Power Cycle your Flight Controller board in order to the changes take effect.

Setup Arming mode (Arduplane specific)
The DROTAG needs to know when the Ardupilot is armed so that it starts a new flight session. With Arduplane, it is frequent that operators do not have any arming modes enabled. These instructions will help you enable the Rudder/Yaw arming settings. The procedure is similar to the TELEM Port Parameters but this time you need to set the Parameters ARMING_RUDDER to 1 and ARMING_REQUIRED to 1 or 2. We highly advise you to read carefully what these parameters do as they may affect your flight operation.

Hot shoe configuration – Optional

Ardupilot Parameters
If your camera has an external flash socket you can use the hotshoe board included with the DROTAG. In Mission Planner, go to the CONFIG/TUNNING tab and select Full Parameter Tree. Now search for the CAM_FEEDBACK_PIN parameter. To select which Pixhawk AUX pin the Hotshoe board is connected to, choose a number between 50 and 55 where 50 corresponds to to AUX pin 0 and 55 corresponds to AUX pin 5. See image 4.4.1 to better understand. Do not forget to press Write Params otherwise, the parameters are not saved. By default, the DROTAGx sets the correct CAM_FEEDBACK_POL parameter and correctly sets the value of CAM_FEEDBACK_POL if the hotshoe functionality is enabled. This way you do not need to set any value on this parameter manually. If you do, the DROTAGx will overwrite it to 0. IMPORTANT: If you enable the hotshoe functionality in the autopilot but do not have the actual hotshoe board installed in the camera the tagging will always fail. This is not a malfunction. When you do not want to use the hotshoe set the CAM_FEEDBACK_PIN to 0 before using DROTAG.

Camera connection
To physically connect the hotshoe board to the camera you need to have it installed as in the picture. It is very important that the center spring contact is facing the camera otherwise the signal does not reach the autopilot and tagging will fail. See example image 4.4.2 to be sure what face needs to be visible when you install the hot shoe on the camera. Another important aspect is that the camera’s flash doesn’t need to be enabled and it should be set be always off.

Preflight Mission Planning
DROTAG relies on Ardupilot messages to trigger the camera and add tags to it, so it is worth taking the time to learn how to efficient mission planning. At Airborne Projects we do the planning of the mission and waypoint upload through Mission Planner. Although planning a mission in Mission Planner or others is outside the scope of this manual there are some details that need to be taken into account. Specifically the “Photo every (est)”. Other parameters and tutorials on Mission Planner can be found on this link. We seriously advise our customers to get comfortable with tutorials as this part of the flight is the only one that is not automated.

Time Between Pictures or “Photo every (est)”
The “Photo every (est)” parameter should not be less than 1.6 seconds unless you have the compatible hotshoe installed and configured. There is no limitation with the hotshoe configured and installed in your camera. If the time between triggers in your mission plan is less than 1.6 seconds the trigger order will be not be issued by DROTAG. It is important to note that this time limit can be broken by flight conditions, like wind. In this case it may happen that the number of pictures predicted does not match the actual taken. This limitation would happen in any case due to the camera’s write speed.

There are many ways around the “Photo every (est)” parameter, each with their own drawbacks. Below, you can find the available approaches in order of best to worse:

1. Slightly Slower Flight – Your mission will take longer to fly but all your pictures will be with the desired Ground Resolution (pixel/cm) which is the normal requirement parameter when doing aerial photography.
2. Higher Altitude – When flying higher you can sacrifice Ground Resolution to obtain pictures with bigger area covered. With bigger area covered in each picture, the more time you have to take next one. You may hit a hard limit on both the altitude as well as on the Ground Resolution requirements.
3. Overlap or Sidelap reduction – It may be possible, due to end use of the collected pictures to reduce the sidelap or overlap of the pictures so that they are less frequent. This increases the time between pictures.
4. 2 passes – You can program the mission to perform the same flight path twice with a slight offset to get the same overlap at the cost of extended mission time. This option is not available automatically by Mission Planner and needs manually create the mission waypoints.

Pre-Flight Checklist
Included in the DROTAG package is a checklist to perform before the flight. This checklist is not manda- tory but is a good practice to guarantee that your fieldwork will be flawlessly done.

1. Verify camera and cables are secure and away from the propeller’s path.
2. Verify if the hotshoe parameters, including mission, are correct for the setup.
3. Power On the camera and check the battery.
4. (Optional) Make sure that the camera settings are correct.
5. Power On the UAV general power.
6. Wait for GPS Lock.
7. The DROTAG system is ready-to-go! Have a nice flight!

Pre-Flight Checklist – Detailed Explanation

1. Verify camera and cables are secure – This item is responsible for no damage or loss of equip- ment. Not getting pictures is bad, destroying your hardware is worse.
2. Power on the camera and check the battery – The camera should be powered before the DROTAG board because the software running will not see any camera available. If the DROTAG board is powered before the camera it can be reset and it will try to check the camera again. Powering on the camera is useful to check if there is any error in the camera. The battery check serves as a situational awareness reminder. It is up to the operator to ensure the camera has enough battery to perform the flight.
3. (Optional) Verify camera settings are correct – This is optional because the camera settings should not change between flights. You should observe this item if the camera settings were previously changed. Incorrect picture settings can make DROTAG under-perform severely because some settings can cause the camera to have big delays between trigger and picture shooting, blocking DROTAG while flight is carried on normally. Incorrect picture settings can also lead to blurry, dark or white pictures. Standard guidelines to camera settings are given in the appendix.
4. Power On the UAV general power – This will power all the system as well as the DROTAG board allowing it to take control of the camera.
5. Wait for GPS Lock – The Ardupilot needs to acquire a 3D Fix to have a position estimate. The position estimate of Ardupilot is what enables coordinates tagging into the picture. The way you check for this event is not the same in all the Ardupilot/GPS receivers. On the Pixhawk when the LED is green the GPS is locked and this item is passed.
6. DROTAG System is Ready to Go! – The operator can take off and start the mission knowing the camera system is working.

In Flight Capabilities
You can only interact with DROTAG in flight by associating an RC channel to a Camera trigger. All other interactions are automatically triggered by Ardupilot.

Manual triggering from RC (ArduCopter only)
If you want to manually trigger DROTAG you can configure an RC channel to do it. For this follow the instruction is taken from the Ardupilot documentation page for example for channel 7:

• Open Mission Planner and then click on CONFIG/TUNING | Full Parameters List;
• Set the value of CH_OPT to 9
• Write Parameters and reboot.

The camera should now trigger on the channel 7 toggle.

Flight Behaviour
When DROTAG is flying, it behaves like a simple trigger to the camera and their interaction is very limited. When DROTAG is ready to take pictures the lens of the camera should be out and, if applicable, the screen should be live as if it were ready to take pictures manually. In a normal flight the pictures are not tagged until very specific events happen:

• A pre-programmed mission reached it’s last waypoint.
• A LAND or RTL waypoint is activated.
• LAND or RTL mode are selected.
• The motors are disarmed (Only applicable for ArduCopter)

Before tagging the pictures DROTAG always writes a companion text file with the data of the triggers for additional information is available. For special orders this file can contain additional custom information. When the tagging is being executed the camera is not available for pictures. A clear sign is that the lens is retracted and the screen says it is in USB mode like in the image in 7.2.1. Also most cameras has card activity LED that will be almost permanently ON if DROTAG is still working. It is expected and desirable that the tagging happens in flight but it sometimes can take a while for it to happen. When DROTAG finishes tagging, the camera lens is put out, and a new flight session can commence or DROTAG can be turned off. DROTAG does not need to be restarted for a new flight.

Special Note: Do not take pictures while in RTL or LAND mission or mode

One of the conditions DROTAG is uses to know if it should start tagging is to verify that it is not Return to Launch or Landing mode. This applies also for equivalent mission commands. If you take pictures in this condition DROTAG will take a picture and immediately start tagging after it does so, which may not be what you want. Be aware of this technical detail.

After Flight Capabilities

DROTAG microSD card care
The partition that is visible under Windows also contains hidden boot files necessary for DROTAG to boot and start. If you blindly format the card you will also erase these boot files needing to re-image the card, which is a time-wasting effort. Reiterating DO NOT FORMAT THE CARD IN WINDOWS. Contact us for help in such a task.

Troubleshooting

Reflashing the DROTAGx firmware
DROTAGx should not need to ever be re-flashed, but in case there is an update to the firmware you may be required to reset the firmware. To do so:

Write the image through Windows

1. Decompress the zip file;
2. Download and install; Win32Imager;
3. Select the Image file as the file which was uncompressed. The file ends with .direct;
4. Insert at least an 8GB SD card into your reader;
5. Select the drive letter where the card is in your computer;
6. Press write and wait for a good while;

Write the image through Linux

1. Insert at least an 8GB SD card to your reader;
2. Unmount if it automatically mounts;
3. Unzip the file;
4. sudo apt-get install pv
5. pv | sudo dd of=/dev /mmeb1k0 (device name can be different. Do not choose a partition but a device!);

After flight the camera still has a lens retracted
It can happen, especially after flight sessions with several hundred or thousand pictures that tagging takes a while. The rough numbers we have is that it takes approximately 1 minute to tag 100 pictures. Another way to check if DROTAG is still tagging is to look for the camera’s card activity LED. If it is active then DROTAG is working.

Significant delay in pictures
This happens if the camera was not configured with manual settings. The automatic modes of the cameras always take a certain amount of time find the correct settings. Not only can it take long for the automatic focus to settle but it can also find that long exposure times are adequate. Possible actions are:

1. Follow the recommended setting provided in the appendix.
2. Abnormal behavior. Contact us.

Display is stuck “Camera USB Connecting”

1. Verify that all the cables are not broken;
2. Verify that the telemetry port to which you are connecting has the baud rate set to 57600.
3. The DROTAGx card may have become damaged. Contact Airborne Projects for a re-generated image.

How to verify the systems on the ground
If you have the Mission Planner or any other Ground Control System connected to another telemetry port of your Ardupilot you can test DROTAG.

1. Connect DROTAGx to Ardupilot;
2. Connect Mission Planner to the Ardupilot;
3. Arm Ardupilot;
4. Make sure you have GPS reception;
5. Right-click on the map and press TRIGGER CAMERA NOW;
6. Disarm Ardupilot;
7. Disconnect all the systems;
8. Verify your pictures in the Camera Card;

There are photos missing? Why?
This situation can come from 2 possibilities:

• Flight conditions made the time between pictures inferior than 1.6 seconds and DROTAG automatically skipped the picture trigger.
• The camera card may have been still busy from the previous picture and could not trigger the picture.

When the 1.6-second rule is broken, nothing can be done besides accounting for flight conditions (ground speed) and tweaking the mission according to the recommendations in 5.1 When pictures are being missed because of poor camera card performance you normally can see the file drotag.log in the same directory as the pictures with some technical information and text mentioning that pictures were missed. This normally means that the camera didn’t have a picture matching a known trigger. A good solution is to try another card with better performance.

Display is stuck on “Check Connect Device”
This means the DROTAG did not boot at all even though the USB has power.

1. Verify the card is correctly seated in the DROTAG board.
2. Contact us so we can provide you with a new card image. The procedure is the same as the one for firmware upgrades.

Further Information
DROTAG relies on several open-source projects. Airborne Projects takes open source licenses very seriously and we have a public repository for the modifications made to the open source projects it relies on, fulfilling the clauses of GNU Public License and Lesser GNU Public License where applicable. We are not a company of lawyers so if we made any licensing mistake let us know so we can correct it as soon as possible.

Appendix A Reasons for lack of APM 2.x support
DROTAG does not support APM 2.x and earlier models because these components do not support newer versions of Ardupilot which have critical features for the correct work of DROTAGx. We cannot backport these features to older versions.

Appendix B Considerations on appropriate camera SD Cards.
As you may be aware there are many cards on the market, but not all card models are advised. We advise the Samsung 16GB Class 10 Pro or the Samsung Evo Series cards. There are other adequate cards for use with DROTAG, which can be consulted in this page of Camera Card Benchmarks. A good way to sort the benchmark table by the “Tested Write Ran” which represents Random Write characteristics. This characteristic is important because it makes the DROTAG tagging faster. It is not essential but a very nice characteristic if you want to land and have all pictures already tagged without further waiting. If these cards are not available to you, you should look for cards, with at least a Class 10 rating, although that is a very weak criterion, as this rating only means that such a card can at least write 10 MB/s, which may not be enough for the Sony Alpha 6100. Another aspect that is important for the performance of you camera and DROTAG is that your card should be correctly formatted. We advise that you do avoid formatting the card if possible and just use the default partitioning scheme. This is because naive formatting may misalign the partition and data layout inside the card and make it under-perform very extremely.If you think you may need to format it, then when you unpack your camera card for the first time, use Win32Imager to read it and store the Binary Image of it. If afterward, you need to “format” your card, just write this empty image back to the card. This ensures you have a backup of the card state out of the factory. This may seem ridiculous, but is real, with the added advantage of providing you with a secure erase of your data. You can read more about the technical reasons in this page, but suffice it so say that there are cards that have a best-case write of 11.5MB/s and a worse-case write of 33KB/s.

References

• Mission Planning — Mission Planner documentation
• Fastest microSD Card Speed Tests (May 2023)
• Optimizing Linux with cheap flash drives [LWN.net]
• Win32 Disk Imager download | SourceForge.net

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