The UM6 ultra-miniature orientation sensor from CH Robotics uses rate gyros, accelerometers, magnetic sensors, and an onboard 32-bit ARM Cortex processor to compute sensor orientation 1000 times per second. Sensor orientation is reported using either quaternions or Euler angles over a TTL serial interface at user-customizable rates. The UM6 was designed specifically to be easy to use — an external enclosure protects sensitive electronics, and connectors make it easy to interface with the sensor without making solder connections to the sensor itself.
Overview
The UM6 ultra-miniature orientation sensor—also known as an Attitude and Heading Reference System, or AHRS—from CH Robotics is much more than an IMU. It uses rate gyros, accelerometers, magnetic sensors, and an onboard 32-bit ARM Cortex processor to estimate the absolute sensor orientation 1000 times per second. Sensor orientation is reported using either quaternions or Euler angles over a TTL serial interface at user-customizable rates. A USB-to-serial adapter can be used to connect the IMU to a computer running the free CH Robotics Serial Interface PC application, which allows for easy data visualization, board calibration, and UM6 settings configuration.
The UM6 was designed specifically to be simple to use: an external enclosure protects sensitive electronics, its small size (1.1"×1.4"×0.5") makes it easier to fit into the end system, and connectors mean no soldering to the sensor itself is required. A polarized four-pin male connector on the side of the UM6 matches an included 7.5" cable and provides the lines necessary to power the board and use the main TTL serial interface. Two 12-pin female connectors on the underside of the UM6 provide access to these same pins along with additional, unused Cortex pins and allow the sensor to be plugged directly into a host system, removing the need to run wires to enable the sensor to communicate. (Note: a version of this sensor is also available without the enclosure or connectors.)
The UM6 can be configured to automatically transmit raw sensor data, processed sensor data, and angle estimates at user configurable rates ranging from 20Hz to 300Hz in roughly 1Hz increments. Alternatively, the UM6 can operate in "silent mode,” where data is transmitted only when specific requests are received over the UART. Regardless of the transmission mode and rate, internal angle estimates are updated at 1000Hz to improve accuracy.
The UM6 simplifies integration by providing a number of automatic calibration routines, including rate gyro bias calibration, magnetometer hard and soft iron calibration, and accelerometer "zeroing” to compensate for sensor-platform misalignment. All calibration routines are triggered by sending simple commands over the serial interface.
The UM6 comes factory-calibrated to remove soft and hard iron distortions present in the enclosure. When integrated into the end-user system, additional calibration may be necessary to correct other magnetic field distortions. Magnetometer calibration can be performed using the CH Robotics Serial Interface software.
As of firmware revision UM2B, the UM6 has the ability to interface with an external GPS module to provide position, altitude, speed, and course outputs. Any GPS module that communicates using industry-standard NMEA sentences, such as our LS20031 GPS receiver module, can be used with the UM6.
Product Comparison
We carry several inertial measurement and orientation sensors. The table below compares their capabilities:
Features
  |
| Graph of all three Euler angles displayed by the CH Robotics Serial Interface connected to a CHR-UM6 orientation sensor. |
- On-board EKF produces quaternion outputs and Euler angles (yaw, pitch, and roll) from 3 gyro axes, 3 accelerometer axes, and 3 magnetometer axes
- Automatic gyro bias calibration
- Data output rate adjustable from 20 to 300Hz (data is internally sampled at 1000Hz regardless of the broadcast frequency)
- Supports connection to external GPS and parses GPS data to provide position, heading, and velocity outputs (firmware revision UM2B or newer only)
- TTL UART communication interface (3.3V with 5V-tolerant pins) with baud rates up to 115,200bps can stream data or provide updates on request
- On-board 3.3V regulator simplifies integration
- 5V-tolerant I/O pins for easy integration with 5V systems
- Open-source Cortex firmware (in C) with free development tools
- Open-source PC software (Visual C++) for data visualization, calibration, and AHRS configuration
- Two UARTs, one I²C bus, and one SPI bus are brought out to the bottom female header pins for custom applications
- Plastic enclosure protects electronics and connectors make it easy to interface with it without making solder connections
- Included 4-conductor 7.5" cable
Specifications
- Better than 2° pitch and roll angle accuracy under static test conditions (actual performance will vary depending on calibration and environment; currently, the UM6 is not calibrated at the factory, and angle estimates can deviate as much as 5° from the actual angle on an uncalibrated unit)
- Better than 5° yaw angle accuracy
- 16-bit Euler angle outputs provide 0.01° resolution
- 3.5 – 5V operating range, 3.3V logic level (5V tolerant)
- ±2000°/s maximum measurable rotation rates
- ±2 g accelerometer range
- Weight: 7grams (0.3oz)
- Size: 27.8×35.6×11.5mm (1.1"×1.4"×0.5")
Application Examples
The CHR-UM6 can be used in applications where a compact attitude and heading reference system is needed:
- UAV navigation
- Robotics
- Motion tracking
- General motion sensing
- Platform stabilization
- Image stabilization
- Enhanced GPS navigation
Dimensions
|
Size: |
1.1" x 1.4" x 0.5" |
|
Weight: |
7.1 g1 |
General specifications
|
Interface: |
TTL serial |
|
Baud: |
115200 bps |
|
Minimum operating voltage: |
3.5 V |
|
Maximum operating voltage: |
5 V |
|
Axes: |
pitch (x), roll (y), and yaw (z) |
|
Measurement range: |
±2000°/s (gyro)
±2 g (accelerometer) |
|
Supply current: |
52 mA |
Notes:
- 1
- Without included cable; cable adds 2.4g.
File downloads
- Datasheet for the CHR-UM6 orientation sensor(366k pdf)
- Document rev. 2.3, updated Feb 21, 2013 to correct a problem in the SPI bus description.
- Getting Started with the UM6 Orientation Sensor(675k pdf)
- This application note provides instructions for communicating with, configuring, and calibrating the UM6 and UM6-LT orientation sensors from CH Robotics.
- Understanding Euler Angles(255k pdf)
- The UM6 and UM6-LT orientation sensors use Euler angle representations by default , and this application note from CH Robotics helps explain what Euler angles are.
- Understanding Quaternions(57k pdf)
- The UM6 and UM6-LT orientation sensors can represent orientation with quaternions, which avoid certain problems that can occur when using Euler angles. This application note from CH Robotics helps explain what quaternions are and how to use them.
- Estimating Velocity and Position Using Accelerometers(43k pdf)
- This application note describes how to use the UM6 or the UM6-LT to estimate velocity and position (dead-reckoning using accelerometers). It also explains why this estimate will not be accurate enough for most applications.
- Sensors for Orientation Estimation(127k pdf)
- The UM6 and UM6-LT orientation sensors each use a three-axis accelerometer, gyro, and magnetometer to estimate orientation. This application note explains in more detail the purpose of each sensor and the math involved in combining them.
- Reprogramming the Firmware on the UM6 and the UM6-LT(243k pdf)
- The UM6 and UM6-LT orientation sensors are designed to be easily reprogrammed when a firmware upgrade is needed. This appplication note provides a detailed description of how to reprogram both devices.
No recommended products at the moment.
No recommended products at the moment.
