The UM7-LT orientation sensor from CH Robotics is an Attitude and Heading Reference System (AHRS) that contains a three-axis accelerometer, rate gyro, and magnetometer. It combines this data using an Extended Kalman Filter to produce attitude and heading estimates.
The UM7 orientation sensor is a third-generation Attitude and Heading Reference System (AHRS) from CH Robotics that produces attitude and heading estimates from triaxial accelerometer, rate gyro, and magnetometer data. Unlike a typical inertial measurement unit (IMU), which only provides raw sensor readings, the UM7 features an onboard microcontroller that combines sensor data using a sophisticated Extended Kalman Filter (EKF) to generate orientation estimates 500 times a second.
Two versions of the UM7 are available: the UM7 orientation sensor, which includes an enclosure, and the UM7-LT, which does not. The two versions are functionally equivalent, and both include a cable (even though it is only shown in one of the two pictures below).
The UM7 features a number of improvements over its predecessor, the UM6, including higher gyro bias stability and lower noise, a new communication architecture for improved flexibility, optional NMEA packet transmission, UTC time-synchronisation with external GPS, and support for third-order temperature compensation on all sensors. It takes advantage of newer MEMS (micro-electro-mechanical systems) technology that allows it to offer better performance at a lower price.
Connections for power and TTL serial communication can be made to the UM7 through a polarized five-pin male connector on one side, which mates with an included cable assembly. A pair of six-pin expansion headers on the other side of the board provide additional connectivity options, including an alternative SPI interface and a secondary serial interface that can be connected to an external GPS module (like our LS20031 GPS receiver). Additional cable assemblies for the expansion headers are not included.
You can use a general-purpose USB-to-TTL-serial adaptor, such as our CP2104 carrier, to connect the UM7 to your computer. You can then use the CHR Serial Interface (available in the “Resources” tab) to configure the sensor, and view and log data in real-time.
Product #2740 is the LT version of the UM7, which is just the UM7 electronics without the enclosure.
As of July 18, 2014, we are shipping UM7-LT modules with the latest firmware version, U71C. Boards that shipped before this date have older firmware versions (U71A or U71B) with issues that might prevent correct operation of the SPI bus and/or cause a steady angular drift in the outputs of the UM7 in certain circumstances (due to improper EKF initialisation). The firmware version can be checked with the CHR Serial Interface software. If you purchased a UM7-LT with older firmware from us and these issues are affecting you, please contact us for firmware upgrade instructions.
We carry several inertial measurement and orientation sensors. The table below compares their capabilities:
|Gyros (3x)||Accels (3x)||Mag (3x)||Altitude||Roll||Pitch||Yaw||Quaternion||Enclosure|
|Pololu MinIMU-9 v5|
|Pololu AltIMU-10 v5|
|CH Robotics UM7-LT Orientation Sensor|
|CH Robotics UM7 Orientation Sensor|
In this video playlist, Caleb Chamberlain from CH Robotics shows how to get started with the UM7, configure its communication settings, and calibrate its magnetometer.
|Size:||1.06″ × 1.02″ × 0.26″|
|Interface:||TTL serial, SPI|
|Minimum operating voltage:||4 V|
|Maximum operating voltage:||5.5 V|
|Maximum logic voltage:||3.3 V2|
|Axes:||pitch (x), roll (y), and yaw (z)|
±8 g (accelerometer)
±12 gauss (magnetometer)
|Supply current:||50 mA|