RedEdge-MX Integration Guide

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RedEdge-MX Integration Guide      Rev 03


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MicaSense RedEdge-MXTM 

Multispectral Camera

 

Integration Guide

 

 

Revision: 03 – April 2019

 

 

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MicaSense, Inc.

Seattle, WA


 

 

Table of Contents

 

Introduction and Scope        3

What’s Included?        3

Camera Dimensions and Mass        4

Lens and Imager Information        4

Attachment Points        5

Inputs and Outputs        6

External Power and External Trigger (“PWR/TRG”)  7

Downwelling Light Sensor 2 (DLS 2)  10

Measurements and Attachment Points  11

DLS 2 Connectors and Buttons  12

DLS 2 Installation Guidelines  13

Fixed-wing  14

Multirotor  14

Serial and Ethernet Data (“COMM”)  14

Example Integrations        16

Standalone Integration Using Camera, DLS, GPS Module  16

Integration with Aerial Platform for Triggering  18

Deep Integration with Host Platform  19

Addition of Top of Frame Capture to Integration  20

Example Integration        21

 

 

 

 

 


 

  1. Introduction and Scope

 

This document provides the information required for mechanical and electrical integration of a MicaSense RedEdge-MX multispectral camera onto a host aircraft.  

  1. What’s Included?

  • RedEdge-MX sensor
  • DLS 2 sensor
  • Edimax Wi-Fi adapter
  • 32 GB SDHC Class 10 SD card (SanDisk Extreme)
  • 15 cm 12-pin Ethernet Cable (DF13)
  • 15 cm 3-pin power cable (DF13)
  • 60 cm DLS 2 connector cable
  • Pelican case
  • Lens cover (opaque - not for use during operation)
  • M3 x 10mm screws, washers (QTY 4)
  • M2 x 6mm screws, washers (QTY 2) 
  1. Camera Dimensions and Mass

                       

 

*All dimensions in mm

 

  1. Lens and Imager Information

 

The imager and lens characteristics are:

 

 

Field of View

47.2 deg HFOV (5.4 mm Focal Length)

Aspect Ratio

4:3

Sensor size

4.8 mm x 3.6 mm , 1280 x 960 Global Shutter

  1. Attachment Points

 

The RedEdge-MX camera can be attached to the host aircraft using at least 2 of the 4 provided threaded mounting points. It is important to use threaded points opposite of each other. M3x0.5 screws are used for this purpose.

 

*All dimensions in mm

  

 

                        CAUTION        

Do not use a screw that will extend into the threaded holes by more than 3 mm (0.125”). Use a washer or other spacer to ensure that the screws do not go into the camera too far.

 

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NOTE

A very light coating of non-permanent thread locker can be used to prevent the screws from coming loose due to vibration. Wipe off excess thread locker from screw prior to insertion.

 

Recommendations for Installation

 

  • The camera should be installed such that it has a clear view of the area directly below the aircraft. The “cone” of the lenses (47.2 degrees total Horizontal Field of View) should be considered in the process of deciding where to mount the camera on the aircraft or payload bay.
  • Thanks to global shutter imager technology, the camera is able to withstand some vibration without degrading image quality; nevertheless, vibration isolation between the camera mounting platform and the aircraft is recommended.
  • Use of a gimbal is recommended to ensure that the camera is pointing straight down (with respect to the earth) at all times during flight. This gimbal system need only be a “servo-driven” gimbal (for pointing as opposed to high-frequency stabilization). A brushless motor type gimbal (mass-balanced, free-floating) can also be used, but it is not required.
  1. Inputs and Outputs

 

The RedEdge-MX camera features 3 connectors for interface to peripherals and to the host aircraft. A fourth connector (USB Type A) is used for the Wi-Fi module (included).

 

 

  1. External Power and External Trigger (“PWR/TRG”)

  • Signal definitions and connector

 

 

Pin #

Signal

1

Trigger

2

Ground

3

Power

 

Connector on Camera

Hirose DF13A-3P-1.25H(51)

Mating Connector

Hirose DF13-3S-1.25C

28AWG wire recommended

 

 

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  • Power Input

 

 

Item

Value

Nominal Voltage

5.0 V DC

Input Voltage Range

4.0V-15.8V DC

Average Power

3.5 Watts average, 8.0 W peak (Camera Not Providing Power to External GPS Module)

4.0 Watts average, 8.5 W peak (Camera Providing Power to External GPS Module)

 

  • The average power requirement of the RedEdge-MX integrated with a DLS 2 is 4.0W. However, the camera can require instantaneous power of up to 8.0W during operation for brief periods of time.  Ensure the power supply can reliably source 8.0W during operation while remaining within the operating voltage range. Operation outside of the specified input voltage range may result in unreliable operation or damage to the camera.

 

  • The RedEdge-MX contains under-voltage and over-voltage protection circuitry which nominally applies at 3.8V and 16.0V.  However, over the operating temperature range these cutoff voltages can vary by up to 0.2V.  For reliable operation, ensure the supply voltage remains within the operating input voltage range at all times over the full range of operating conditions.

 

  • Trigger input: The camera can be triggered either with a rising-edge pulse, falling edge pulse or a PWM signal (such as is typically used with standard servos). When using a PWM signal as the trigger, the camera detects a transition from a “long” PWM to a “short” PWM  (or vice-versa depending on the configuration setup of the camera)

 

 

 

 

Item

Value

Nominal Voltage

3.0 V DC

Voltage Range

0.0 V DC to 5.0 V DC

Absolute Maximum Voltage

5.1 V DC

PWM Trigger Expected Range

1.0 ms to 2.0 ms

 

 

 

CAUTION

Care should be taken when multiple “grounds” are used for power and trigger of the camera. Only one ground should be connected to the camera – typically this is the ground that corresponds to the source of the power. If the ground of the trigger signal and the ground of the power source are different, they should not be joined together electrically at the camera. Contact support@micasense.com if further information is needed.

 

 

 

  1. Downwelling Light Sensor 2 (DLS 2)

The Downwelling Light Sensor (DLS 2) is an advanced incident light sensor that connects directly to RedEdge-MX. During a mission, the DLS 2 measures the ambient light and sun angle for each of the five bands of the camera and records this information in the metadata of the TIFF images captured by the camera. This information can then be used by specialized processing tools (like Pix4Dmapper) to correct for global lighting changes in the middle of a flight, such as those that can happen due to clouds covering the sun.

 

In addition, the DLS 2 provides GPS data to RedEdge-MX unless GPS data is provided from an external source as outlined earlier in this guide. If using an alternative GPS source, the GPS receiver will remain on at very low power (uBlox C/A code GPS @ 5 Hz).

Measurements and Attachment Points

 

Height

14.03 mm

Width

46.00 mm

Length

63.50 mm

Weight

49 g

 

DLS 2 Connectors and Buttons

The sensor kit includes all required interface cables to connect to the DLS 2.

The LED camera status indicator mimics the LED signals on RedEdge-MX. The signal types are outlined in the Sensor User Guide. The camera trigger button will command a capture on the RedEdge-MX. This is useful for capturing a preflight image of the calibration panel.

 

The RF connector is not available for use at this time but may be used as in the future. When it is available, we will update this guide.

  

 

Pin #

Signal

Direction

1

5.0 V DC Output

Output From Camera

2

DLS 2/GPS RX

Output From Camera

3

DLS 2/GPS TX

Input To Camera

4

GPS IO 0 (Configurable)

Input To Camera/Output from Camera

5

GPS IO 1 (Configurable)

Input To Camera/Output from Camera

6

Ground

Ground

 

Connector on Camera

Hirose DF13A-6P-1.25H(51)

Mating Connector

Hirose DF13-6S-1.25C

28AWG wire recommended

DLS 2 Installation Guidelines

The DLS 2 should always be the highest object on the aircraft in order to avoid shadows or reflections. It contains an integral GPS sensor that may be utilized for geotagging of the RedEdge-MX imagery if system GPS signals are not provided to the sensor by other means. Install the module where it will have a clear view of the sky, far away from any devices that could interfere with it (like a data link or video transmitters).

 

When the DLS 2 starts up, it attempts to calibrate, which requires it to be still and motionless.  Ensure that there is no vibration or movement until the DLS 2 has completed this procedure, indicated by normal LED status lights (shown in the User Guide).

 

 

NOTE

The 6-pin connector on the DLS 2 should be facing forward in the flight direction. Mounting it in the opposite direction will cause the magnetometer calibration process to be backwards.

 

Fixed-wing

Always install the DLS 2 at the high-point of the fuselage (if possible) to avoid any shadowing or reflections from aircraft fuselage or rotors.

 

Do not recess or embed the DLS 2 sensor body below the metallic base.

 

Local reflections could impact light sensor measurements. Avoid bright or metallic paint near the DLS 2 light sensor as this may interfere with incoming light values.

Multirotor

Install the DLS 2 on a rigid post such that it is the highest object on the aircraft, with a minimum of 5 cm above the rotor plane.

 

Ensure that there are no obstructions in the DLS 2’s field of view to the sky, including propellers and other items on the aircraft.

 

Keep the DLS 2 away from the aircraft GPS. Installing the DLS 2 near the aircraft GPS may impact the aircraft’s GPS reception.

 

  1. Serial and Ethernet Data (“COMM”)

 

This connector is available for tighter integration with host aircraft. It includes a standard TTL-level serial port as well as an Ethernet port. Documentation for the communications protocol is available by contacting MicaSense.

 

 

Pin #

Signal

Direction

1

Serial RX (3.3 V)

Output From Camera

2

Serial TX  (3.3 V)

Input To Camera

3

Serial Ground

Ground

4

Ethernet RX P (B+)

Output From Camera

5

Ethernet RX N (B-)

Output From Camera

6

Ethernet Line Ground

Ground

7

Ethernet TX P (A+)

Input To Camera

8

Ethernet TX N (A-)

Input To Camera

9

Ethernet RX P 1G (D+)

Output From Camera

10

Ethernet RX N 1G (D-)

Output From Camera

11

Ethernet TX P 1G (C+)

Input To Camera

12

Ethernet TX N 1G (C-)

Input To Camera

 

Connector on Camera

Hirose DF13A-12P-1.25H(51)

Mating Connector

Hirose DF13-12S-1.25C

28AWG wire recommended


 

  1. Example Integrations

 

RedEdge-MX is designed for integration into a variety of platforms.  Below are some common integration configurations.

  1. Standalone Integration Using Camera, DLS, GPS Module

 

The standalone integration option requires only that power is provided to the RedEdge-MX system. Triggering is configured via the WiFi interface to either “Overlap” or “Timer” mode.  GPS information is provided by the included GPS receiver connected to the DLS.

Automatic Capture/Triggering Options

  • RedEdge-MX supports three methods for capturing images: Overlap, Timer, and External Trigger. To learn more about how to configure these settings, please see the Sensor User Guide.
  • Overlap Mode (Recommended)
  •  In overlap mode, when the aircraft climbs to within 50 meters below your target altitude, RedEdge-MX will start capturing and only take a capture if it has traveled forward enough distance to ensure the overlap percentage you have specified. When the sensor's altitude is below 50 meters from the target altitude, the sensor stops capturing. Overlap mode only calculates the forward overlap, and cannot account for the side overlap, which must be calculated in a flight planner, using the sensor’s field of view to create an appropriate row spacing.
  • We recommend this mode because it helps ensure proper overlap (75% or higher), which is essential in order to produce high-quality output when processing the data in standard photogrammetry software.
  • Timer Mode
  •  When in timer mode, RedEdge-MX will capture according the timer period (which is every two seconds by default). If the timer period is set to less than one second, the sensor will capture as quickly as it can (about once every second). The capture rate is heavily dependant on the write speed of the attached storage device.
  1. Integration with Aerial Platform for Triggering

 

Using the RedEdge-MX trigger input, the host platform can command image capture at optimal times based on the operation profile. This allows the operation planning to be conducted through the host vehicle mission planning software without the need to configure the camera for operation over WiFi at the start of each operation.

 

In this integration triggering can be commanded via a rising-edge pulse, falling-edge pulse, or most commonly, using a PWM signal such as a standard servo pulse. When using a servo pulse, RedEdge-MX can trigger image captures  when the pulse transitions from short to long (e.g. 1.0ms to 2.0ms) or long to short (e.g. 2.0ms to 1.0ms). These trigger settings are configurable via the WiFi interface, and are persistent once saved.

 

 

  1. Deep Integration with Host Platform

 

The RedEdge-MX supports deep integration with host platforms allowing the replacement of the included GPS receiver with host-provided GPS information. In this mode, GPS location, altitude, and time, as well as platform orientation information is provided via the host serial or Ethernet interface. Host integration through serial connection is accomplished through MAVLink messaging and is compatible with common autopilot systems such as Pixhawk and APM. Deep integration in this manner is best performed by integrators with a strong working knowledge of the MAVLink communication protocol, serial communications, and advanced Pixhawk or APM configuration. Ethernet connectivity is also an option - visit support.micasense.com for further resources on either of these two protocols.

 

 

  1. Addition of Top of Frame Capture to Integration

 

For integration with RTK and/or PPK GPS systems, or other systems requiring precision timestamping of image capture, the Top of Frame output (ToF) can be used to precisely log the start of image exposure with an accuracy of a few tens of nanoseconds. The ToF function is available for use in any of the integration scenarios listed above, though typically the aircraft will be providing both triggering as well as GPS/IMU information to the camera via serial/Ethernet protocol.

 

To use RTK/PPK GPS with sync output from camera, a custom 6-pin cable will be needed, which connects to the “DLS/GPS” connector on the camera. One end of the cable will connect to the DLS and the other end (with Ground and Pin 4 - see table in Section 5.1.2) would connect to the RTK/PPK GPS receiver or associated computer.


 

Example Integration

 

 

 

 

MicaSense RedEdge-MXTM  Multispectral Camera

Integration Guide

Rev 03 – April 2019

 

MicaSense, Inc.

Seattle WA 98103

 

 

 

  • The contents of this guide are subject to change without notice
  • MicaSense, Inc. assumes no liability for incidental or consequential damages arising from the use of this product, and any claims by a third party.
  • Copying of the contents of this guide, in whole or in part is prohibited under the copyright law.

© 2019 MicaSense, Inc.                                                                                                       

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