Camera Shutter Triggering using Stratosnapper¶
This tutorial shows how to automatically trigger the camera shutter from ArduPilot using a Pixhawk and Stratosnapper V2 (with an IR Module).
The Stratosnapper v2 board supports a large number of output types: cables/connectors, infra-red, LANC, etc. The approach described in this article could be extended to target a broad range of cameras from many popular brands.
ArduPilot allows you to configure a servo or relay output as the control signal for the camera shutter so that it can be used in Camera Missions. Additional hardware is required to convert the shutter activation signal to the format expected by the particular camera.
This tutorial shows how to set up a Pixhawk to connect to a Sony NEX5 using the Stratosnapper v2 board with an IR trigger. This configuration has been selected because the NEX5 is widely used for aerial photography in UAVs, and because an IR Trigger does not require an extra cable connected to your camera.
Parts and hardware connections¶
The diagram below shows the required parts and general cabling. This includes the Pixhawk, IR Trigger device (Stratosnapper), IR LED and camera, and the BEC to power the Stratosnapper.
Pixhawk has 6 AUX ports that may be used for triggering the camera (see AUX1-AUX6 = RC9-RC14). This tutorial uses port 2/AUX2, as shown in the diagram below:
IR trigger device¶
The Stratosnapper with its inputs/outputs is shown below. The servo inputs can be push-buttons, sticks, two or three-way switches, etc. These are configured using a GUI configuration utility from your PC via USB.
Note the two servo leads are connected on the input side of Stratosnapper; one of these is to power the IR module.
It is not possible to power the IR module (or any other device) from the Pixhawk AUX ports. You must either power provide a separate BEC to power the IR device or power the Pixhawk outputs rail with a BEC and power the device off that.
The control signal from Pixhawk can be assigned to any of the 4 servo inputs.
The output of the Stratosnapper is shown below. It connects to an IR cable, which in turn triggers a IR led that must be placed in front of your camera IR sensor:
IR LED positioning and camera gimbal¶
Shown here is a picture of X8 Mr Grey (formerly known as Mr Red when was used with APM).
The electronics are protected using a grey flower pot (the only colour my wife had!) and we used some green gardening wire to shape the IR LED cable so it is correctly positioned in front of the camera’s IR sensor. Gardeners & farmers are notoriously UAV friendly :-)
The Sony NEX5 is held in a 2-axis stabilized brushless gimbal (NEX5 not shown...used to take this picture). Here below a zoomed view of the IR LED positioning and gimbal:
The IR LED works well even in bright sunlight (verified in the field). It also works some distance from the sensor (no problem within 5inches of the Sony NEX5 sensor) and in any orientation with respect to the sensor.
Camera shutter configuration in Mission Planner¶
The Camera Shutter Configuration in Mission Planner article explains how to configure Pixhawk AUX output as a servo camera trigger.
The parameters used to configure this Stratosnapper/IR/NEX5 hardware are listed below:
CAM_TRIG_TYPE: 0 (Servo).
Shutter (Port): RC10 (AUX2).
Shutter Pushed: 1800
Shutter Not Pushed: 1100
Shutter Duration: 10 (1 second)
Servo Limits Max: 1900
Servo Limits Min: 1100
CH7_OPT: 9 (Optional - enables manual shutter triggering on Copter only).
IR device configuration (Stratosnapper V2)¶
Every IR device has its own configuration method. Stratosnapper comes with a simple GUI interface to define which PWM values will trigger what port.
The IR device configuration is explained in this video:
Testing and mission planning¶
Once a camera trigger has been defined it can be used in Camera Control and Auto Missions to take pictures and make area surveys.
The configuration in this article was tested when creating the Survey (Grid) Example.
I hope this will help you in your own auto-photo-shoot missions! Cheers, Hugues