This six-DOF IMU from CH Robotics packs three accelerometer axes, three gyroscope axes, and a STM32F103T8 ARM Cortex processor into a tiny, 0.8" x 0.7" x 0.1" board.
The small size and light weight (1.5 g) make the board well suited for unmanned aerial vehicle (UAV) navigation.
The integrated 32-bit MPU takes 16-bit readings of the sensors, applies a customizable filter, and reports the results via a TTL serial interface.
The Cortex’s programming pins are exposed, and the firmware is open-source.

Overview

The CH Robotics CHR-6d inertial measurement unit (IMU) uses a 32-bit STM32F103T8 ARM Cortex processor to take 16-bit ADC readings from an ADXL335 three-axis accelerometer, a LP510AL pitch/roll rate gyro, and a LY510ALH yaw rate gyro, providing a full six degree of freedom (6-DOF) measurement solution. The Cortex processor applies a customizable finite impulse response (FIR) digital filter to help reduce noise and makes the results available via a simple TTL-level (3.3V with 5V-tolerant pins) serial interface at baud rates up to 115,200 bps.

A USB-to-serial adapter can be used to connect the IMU to a computer running the free IMUkit PC application, which can be used for data visualization and settings configuration.

Note that the board’s pins are spaced 2 mm apart, so the board will not work with standard 0.1" headers or breadboards.

For an Attitude and Heading Reference System (AHRS) version of this IMU that features an additional 3-axis magnetic compass and outputs yaw, pitch, and roll angles and angle rates, please see the CHR-6dm Attitude and Heading Reference System.

Features

• On-board EKF for pitch and roll angle estimation (firmware version 2.0+ only)
• 3 gyro axes and 3 accelerometer axes
• ±400°/s gyro range
• ±3 g accelerometer range

• Data output rate adjustable from 20 to 300 Hz
• Weighs under 1.5 grams (0.05 oz)
• Small size: 20 x 18 x 3 mm (0.8" x 0.7" x 0.1")
• Configurable windowed Parks-McClellan FIR filter
• TTL UART communication interface (3.3V with 5V-tolerant pins) can stream data or provide data on request
• 16-bit measurement resolution
• Cortex firmware and PC application can be customized

Open Source PC Application and Firmware

Both the PC application for communicating with the CHR-6d and the CHR-6d’s firmware are open source and available for download from the Resources tab. All of the pins needed to reprogram the STM32F103T8 ARM Cortex processor are made available to the user, as are four unused digital I/O pins that can be put to use if the firmware is modified.

Application Examples

The CHR-6d can be used in applications where a compact, 6-DOF IMU is needed, including:

• UAV navigation
• Robotics
• Motion tracking
• Platform stabilization
• Image stabilization
• Supplement to GPS navigation