CTR Electronics Pigeon 2.0 User manual

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Pigeon 2.0
User’s Guide
Revision 1.0
Cross The Road Electronics
www.ctr-electronics.com

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Table of Contents
1. Device description .....................................................................................................................................................5
1.1. Kit Contents........................................................................................................................................................5
1.2. Features..............................................................................................................................................................6
1.3. Electrical/Inertial Specifications.........................................................................................................................7
1.4. General/Mechanical Specifications....................................................................................................................7
1.5. LED States...........................................................................................................................................................8
1.6. Functional Diagram ............................................................................................................................................9
1.6.1. Mount Orientated Signals...........................................................................................................................9
1.6.2. Enclosure Orientated Signals ......................................................................................................................9
1.7. Changes between Pigeon 1 and Pigeon 2 ........................................................................................................10
2. IMU Error Sources....................................................................................................................................................11
2.1. Location –Center of Rotation ..........................................................................................................................11
2.2. Temperature ....................................................................................................................................................11
2.3. Gyroscope Sensitivity Error ..............................................................................................................................12
2.4. Avoid Magnetic/Ferromagnetic materials .......................................................................................................13
2.5. Vibration...........................................................................................................................................................14
2.6. Saturated inputs...............................................................................................................................................14
3. Calibration ...............................................................................................................................................................15
3.1. Temperature Calibration..................................................................................................................................15
3.2. Gyroscope Bias Calibration...............................................................................................................................15
3.3. Gyroscope Sensitivity Calibration.....................................................................................................................15
3.4. Accelerometer Calibration ...............................................................................................................................15
3.5. Compass Calibration.........................................................................................................................................15
4. Boot behavior ..........................................................................................................................................................16
4.1. Boot behavior - Test Results ........................................................................................................................17
5. Wiring ......................................................................................................................................................................19
6. Orientation Convention...........................................................................................................................................20
6.1. World Frame Reference.............................................................................................................................20
6.2. Euler Angles................................................................................................................................................20
6.3. Gimble Lock................................................................................................................................................20
6.4. Does X/Y Axis placement matter?..............................................................................................................21
6.5. Default Mounting Orientation ...................................................................................................................21
6.6. Custom Mounting Orientation...................................................................................................................21
6.6.1. Custom Mounting Orientation –Explicit Values ...............................................................................22
6.6.2. Custom Mounting Orientation –Phoenix Tuner ...............................................................................23
7. FAQ ..........................................................................................................................................................................24

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7.1. Is there a way to tell if the device is present/powered?..................................................................................24
7.2. How do I change the Mount Orientation? .......................................................................................................24
7.3. What changes do I need to make when upgrading from Pigeon (1) IMU to Pigeon 2.0?................................24
7.4. What are the requirements of Pigeon 2.0 when booting up? .........................................................................24
7.5. Does the device support CAN FD?....................................................................................................................24
7.6. Trying to keep robot from tipping over. Any suggestions? .............................................................................24
7.7. Closed-looping an Arm. Any suggestions? ......................................................................................................24
7.8. When Pigeon IMU boots, starting Yaw is not zero?.........................................................................................24
8. Mechanical Drawings...............................................................................................................................................25
9. Revision History ..................................................................................................................................................26

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TO OUR VALUED CUSTOMERS
It is our intention to provide our valued customers with the best documentation possible to
ensure successful use of your CTRE products. To this end, we will continue to improve our
publications, examples, and support to better suit your needs.
If you have any questions or comments regarding this document, or any CTRE product, please
contact [e-mail]
To obtain the most recent version of this document, please visit
www.ctr-electronics.com.

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1. Device description
The Pigeon 2.0 is an inertial measurement unit (IMU) that can sense acceleration, angular velocity, and magnetic
fields. With this information, Pigeon 2.0 can be used to sense a mobile platform’s pose, which then can be used for
a variety of applications.
1.1. Kit Contents
Each kit contains a single Pigeon 2.0 IMU.
IMU is preassembled and includes wire leads
for power and CAN bus.
The CAN bus wire leads are terminated with
3-pin pre-installed connectors (0.1” pitch).
One lead pair has a female connector, and
the other has a male connector. This way,
several CTR-Electronics CAN bus devices can
be daisy chained together.

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1.2. Features
•Nine Degrees of Freedom (3 Axis Accelerometer, 3 Axis Gyroscope, 3 Axis Magnetometer)
•Full AHRS: Yaw, Pitch, Roll
•Quaternion Output
•Gravity Vector Output
•Boot-up does not require stillness. Get useful heading information as soon as it is powered on.
•Kalman Filter fusion algorithm
•Gyro automatically re-biases after 4 seconds of no-motion
•Temperature Compensation for temperature sensitive components
•Temperature factory-calibrated
•Accelerometer factory-calibrated
•Gyroscope factory-calibrated
•No user-calibration required for accurate 6-axis fusion.
•Mount IMU in any orientation (not limited to horizontal or vertical orientation) (Note 1,2)
•Heading and Yaw are continuous, ideal for robot heading servos and motion control.
•Enclosure protects against debris
•Wide Input Voltage Range 6V –28V
•Protection Reverse Input Power Protection
•Polycarbonate housing prevents debris from entering inside device
•One wire lead-pair for power
•Two wire lead-pairs for CAN Bus (3-pin connector, one male, one female) for daisy chaining devices
•Robust bootloader and reliable field-upgrade (no physical button required, no “stuck states” that
requires user intervention)
•Wirelessly check, configure and field-upgrade using roboRIO Wi-Fi and Phoenix Tuner.
•Users can download software API binaries on our reliable Maven server (99.999999999% reliability)
•Hardware Simulation Support
•Supports CAN bus and CAN FD bus.
•Supported by CANivore and roboRIO use case
Note 1: Pigeon 2.0 can be configured for any mounting orientation. Other IMUs provide a fixed number of orientations, but
Phoenix Tuner/ Phoenix API can be used to select any orientation.
Note 2: When using Euler angles, user must avoid Gimble Lock conditions for valid Yaw, Pitch, Roll values. This is a limitation of
expressing pose using Euler angles, and not a limitation of the Pigeon IMU.

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1.3. Electrical/Inertial Specifications
Note 1:Device firmware currently selects ±1000 dps. Future software updates may allow configuration based on
customer feedback.
1.4. General/Mechanical Specifications
Outside Dimensions
1.77” x 1.77” x 0.51”
Weight
1.07 ounces (30.39g) w/ enclosure & wires
Supported Communication Protocols
CAN 2.0 (1Mbps)
CAN FD with CANivore
Boot Calibration (Note 1)
0 seconds
Gyroscope bias no-motion time (Note 2)
4 seconds
Mechanical Shock (Note 3)
10,000 g (duration 200 us)
2,000 g (duration 1 ms)
Maximum Free fall (Note 3)
5’
Note 1: Drift rate will start at DR BOOT.
Note 2: Gyroscope is re-biased after 4 seconds of no motion, which reduces drift rate to DR NO-MOTION
Note 3: Stresses above listed rating may cause permanent damage to the device.
Symbol
Parameter
Condition
Min
Typ
Max
Unit
Tamb
Ambient temperature
-40
+85
°C
Isupp
Supply Current
DC supply 12.0V
DC supply 28.0V
40
21
46
23
mA
Vdd
Supply voltage
6.0
12.0
28.0
V
ESD Rating
ESD Protection Contact Discharge
±30
kV
ESD Protection Air-Gap Discharge
±30
kV
Yaw Drift Rates
DR NO-MOTION
No-Motion Drift
0.12
Deg /
hour
DR IN-MOTION
In-Motion Drift
0.4
Deg / min
DR BOOT
Boot-Into-Motion Drift
1
Deg / min
Gyroscope Specifications
Range
Angular Velocity Measurement Range (Note 1)
±125
±1000
±2000
dps
Resolution
Resolution of angular velocity
measurement
16
bits
Accelerometer Specifications
Range
Range Acceleration Measurement
±8
g
Resolution
Resolution Acceleration Measurement
16
bits
Magnetometer Specifications
Range
Magnetometer Range
±1150
uT
Resolution
Magnetometer Resolution
0.3
uT
Accuracy
Compass Accuracy (with proper calibration
and placement)
1
deg

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1.5. LED States
The Pigeon 2.0 features 2 tri color LEDs that indicate CAN bus health. This feature can be used to confirm proper
CAN bus wiring. The table below shows the possible color states.
LED Color
Blink Pattern
Description
Off
Pigeon 2.0 is not powered/ plugged in.
Check power cabling to the Pigeon 2.0.
Yellow/Green
Only one LED will blink this
pattern.
Device is in bootloader, most likely because field-
upgrade failed in middle of event.
Inspect CAN bus wiring and re-field-upgrade using
Phoenix Tuner.
If device has valid firmware, turn device off, wait 10
seconds, and turn device on to boot strap it.
Red/Yellow
LEDs are never off –one of the
two colors are always illuminated
Hardware is damaged
Red Blink
Check CAN Bus health and connection to the Pigeon
2.0.
Yellow
Alternate Blinking (Note 1)
CAN bus detected.
Robot controller is not present on CAN bus, or Pigeon2
software object not created in user application.
Yellow
Simultaneous Blinking (Note 2)
CAN bus detected.
Robot is disabled.
Green Blink
CAN bus detected.
Robot is enabled.
Note 1: Only one LED is on at any given moment.
Note 2: Both LEDs are on at the same time.

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1.6. Functional Diagram
Signal paths are show in the functional diagram below.
1.6.1. Mount Orientated Signals
Note that the Yaw, Pitch, Roll, Quaternion, and Gravity Vector are compensated for the selected Mount
Orientation.
1.6.2. Enclosure Orientated Signals
The outputs of the gyroscope, accelerometer and magnetometer are not
compensated for the selected Mount Orientation.
These signals are biased/calibrated to canonical units. (Note 1).
As a result, these signals are referenced to the enclosure’s orientation.
If these enclosure-oriented signals are used, it is recommended to choose a
Mount Orientation that is reasonably horizontal or vertical so that Yaw, Pitch,
Roll, and Gravity Vector are also aligned to these signals.
Note 1: Magnetometer requires user calibration

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1.7. Changes between Pigeon 1 and Pigeon 2
Pigeon 2.0 is the next evolution in Pigeon IMU. Listed below are the differences between the latest iteration and
the original Pigeon IMU.
Note 1: Both Pigeon 1 and Pigeon 2 use a right-handed orientation, and Pigeon 2 defaults to Z-axis up (similar to Pigeon 1). However, Pigeon
2 uses an X forward orientation to better match the academic research papers used in the development of the product.
Symbol
Pigeon IMU
(Version 1)
Pigeon 2.0
Boot
Requirements
5 seconds of stillness
No requirements
6 Axis angle drift
(no-motion)
15 deg per hour
0.12 degrees per hour
6 Axis angle drift
(motion)
1 deg per minute
0.4 deg per minute (with 4 second no-motion event)
1 deg per minute (instantly after boot-up)
Axes conventions
+X points to right
+Y points to forward
+Z points to sky
Pitch is about +X
Roll is about +Y
Yaw is about +Z
+X points forward.
+Y points to the left.
+Z points to the sky.
Pitch is about +Y
Roll is about +X
Yaw is about +Z
Mount
orientation
Must be mounted flat
and level (Z axis pointed
up)
Mount in any orientation.
Orientation does not need to be purely vertical or
horizontal.
Pitch and Roll can be zeroed this way as well.
Enclosure
None
Polycarbonate Enclosure
Communication
CAN bus
Gadgeteer Ribbon
Cable
CAN bus
CAN FD bus (CANivore)
User
Requirements
(Indoor 6-axis
applications)
Temperature
Calibration for best
performance.
None for best performance.
Select Mount Orientation if using non-default orientation.
General Software
API Changes
PigeonIMU class
WPI_PigeonIMU class
Pigeon2 class
WPI_Pigeon2 class
getState () is not available –there is no need as the IMU is
always read.
getFusedHeading() is not available –there is no need as
IMU Yaw is the fused heading in all circumstances.
Use getYaw() instead.
Full Software documentation available at:
https://ctr-electronics.com/documentation