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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
Quick Start Guide
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.
Contents
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4.1 Sony Alpha Specifics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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Tethering setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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Focus Mode setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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4.2 Setup your TELEM Port Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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5.1 Time Between Pictures or "Photo every (est)" . . . . . . . . . . . . . . . . . . . . . . . . .
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7.1 Manual triggering from RC (ArduCopter only) . . . . . . . . . . . . . . . . . . . . . . . . .
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Special Note: Do not take pictures while in RTL or LAND mission or mode . . . . .
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8.1 DROTAG microSD card care . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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9.3 Display is stuck "Camera USB Connecting" . . . . . . . . . . . . . . . . . . . . . . . . . .
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9.4 There are photos missing? Why?
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9.5 Display is stuck on "Check Connect Device" . . . . . . . . . . . . . . . . . . . . . . . . . .
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Appendix A How to update DROTAG’s firmware
Appendix B Considerations on appropriate camera SD Cards.
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1 Context
This User Guide’s goal is to get DROTAG working with your tethering camera and your APM based Flight
Controller module.
DROTAG is a small board that simply sits between your camera and your Flight Controller (like Pixhawk), allowing you to remote trigger the camera (manual or automatically) and have the taken pictures automatically geo-tagged. The pictures are tagged in the camera itself.
Currently just the main Sony Alpha Series cameras were tested (A5000, A5100 & QX1).
2 Assumptions
1. The DROTAG module is connected to one of the available telemetry output found on your flight controller (Pixhawk/APM/NAVIO/etc);
2. The power to the DROTAG is supplied by the autopilot’s telemetry port;
3. The microSD card that came with your package is inserted in the DROTAG board. This item is setup by Airborne Projects.
4. To get the pictures geo-tagged you need a GPS fix on your Autopilot. Without it, DROTAG will not trigger the camera
5. The microSD card image you receive is bound to your DROTAG serial number. That means you can use any microSD card you wish but you can only run it on your board. If you would like to run
DROTAG in another board contact us at our email;
3 Package Contents
1.
DROTAG board;
2. 16GB Class 10 microSD card loaded with DROTAG software;
3.
DROTAG Quick Start Guide;
4. An Operation Checklist;
4 Hardware installation
Below you can find a picture illustrating the installation. We point out that good practices are advised regarding fixation of the board.
Boards and Cables should be stowed clear of propellers in a vibration resistant manner.
4.1
Sony Alpha Specifics
There are 2 camera settings DROTAG can’t change automatically, which are important for aerial photography. The tethering setting and the focus mode. In the following instructions you will learn how to make these one-time configurations to your Sony Alpha 5000 Series camera. The procedure for other Sony
Alphas are analogous although with slightly different steps than the exemplified below.
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4.1.1
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;
4.1.2
Focus Mode setting
• 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 ∞.
4.2
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 SERIAL1 prefix corresponds to TELEM1. If you would like to use TELEM2 the applicable parameters are prefixed by SERIAL2. Accordingly, prefix SERIAL4 corresponds to 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:
(a) SERIAL1_BAUD 57
(b) SERIAL1_PROTOCOL 1
5. Click
Write Params
6.
Power Cycle your Flight Controller board in order to the changes take effect.
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5 Preflight Mission Planning
DROTAG relies on APM 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 which is not automated.
5.1
Time Between Pictures or "Photo every (est)"
The "
Photo every (est)" parameter should not be less than 1.6 seconds. If the time between triggers in your mission plan is less than 1.6 second 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:
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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.
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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 creating the mission waypoints.
6 Pre-Flight Checklist
Included in the DROTAG package is a checklist to perform before the flight. This checklist is not mandatory but is a good practice to guarantee that your field work will be flawlessly done.
1. Verify camera and cables are secure and away from the propeller’s path.
2.
Power On the camera and check battery.
3. (Optional) Make sure that the camera settings are correct.
4. Power On the UAV general power.
5. Wait for GPS Lock.
6. The DROTAG system is ready-to-go! Have a nice flight!
6.1
Pre-Flight checklist - Detailed Explanation
1.
Verify camera and cables are secure - This item is responsible for no damage or loss of equipment. Not getting pictures is bad, destroying your hardware is worse.
2.
Power on the camera and check 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 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 observer 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 APM needs to acquire a 3D Fix to have a position estimate. The position estimate of APM is what enables coordinates tagging into the picture. The way you check for this event is not the same in all the APM/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.
7 In Flight Capabilities
You can only interact with DROTAG in flight by associating an RC channel to Camera trigger. All other interactions are automatically triggered by APM.
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7.1
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 taken from 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 channel 7 toggle.
7.2
Flight Behaviour
When DROTAG is flying, it behaves like 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 way point.
• 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
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.
7.2.1
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
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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.
8 After Flight Capabilities
8.1
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 this 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.
9 Troubleshooting
9.1
After flight the camera still has a lens retracted
It can happen, specially after flight sessions with several hundreds 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.
9.2
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.
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9.3
Display is stuck "Camera USB Connecting"
When this happens it means the DROTAG is correctly booting but not taking over the camera. This may mean that the main program is not running. Possible actions are:
1. View hidden files in the microSD card and try to check if the executable ./telepresence_gstreamer is there. If it is not, you may have inadvertently deleted it. Please contact us.
2. Power cycle the DROTAG board and wait 30 seconds. The screen should disappear.
3. Contact Airborne Projects.
9.4
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 been 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 tweak 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 camera didn’t have a picture matching a known trigger.
A good solution is to try another card with better performance.
9.5
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 upgrade.
10 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.
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Appendix A How to update DROTAG’s firmware
To update the firmware you just need to contact us through [email protected] and request the new application binary. You will need to open the DROTAG, take out the SD Card and run Win32Imager with the new card image. In the future we will provide a simpler upgrade mechanism where the software can most of the times be upgraded through the camera itself.
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 Class 10 rating, although that is a very weak criteria, 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 which 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 a 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 afterwards 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 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 which have a best case write of 11.5MB/s and a worse case write of 33KB/s.
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