SDK ROS2 Package Reference

File Layout

The ROS2 portion is in rdk-imu-module-sdk/ros2 and depends on the C API. The ros2 directory is a colcon workspace:

Before build:

ros2/
└── src
    └── rdk_imu_module
        ├── CMakeLists.txt          # Build configuration
        ├── launch
        │   └── rdk_imu.launch.py   # Launch file
        ├── package.xml
        ├── scripts
        │   └── imu_stress_test.py  # Stress test script
        └── src
            └── rdk_imu_node.cpp    # Node source

After build:

ros2/
├── install/
├── build/
├── log/
└── src/

Build Instructions

Before building the ROS2 package, compile the C API shared library so core/lib contains .so, .so.x, and .so.x.x.x. The ROS2 package depends on that library; CMake detects and installs it into install automatically.

With your ROS2 environment sourced, run colcon build from the ros2 directory.

API Reference

Node Behavior

• Fused output: Calls C API rdk_imu_read_fused() for 1D linear interpolation and time-aligned 6-axis data.
• Automatic covariance: Computes diagonal entries of linear_acceleration_covariance and angular_velocity_covariance from configured accelerometer filter bandwidth and gyroscope bandwidth, using BMI088 noise density from the datasheet.
• Runtime control: ROS2 services to pause/resume IMU data acquisition at any time.
• Flexible parameters: Sensor settings, topic names, and service names are configurable via ROS parameters at launch.

Launch

Ensure the ROS 2 package is built and the workspace is sourced, then launch:

source install/setup.bash
ros2 launch rdk_imu_module rdk_imu.launch.py

The node runs as rdk_imu_node and logs to the console by default.

Published Topics

• Default topic: /rdkimu/data

• Message type: sensor_msgs/msg/Imu

• Contents:

  • header.stamp: fused timestamp (nanosecond hardware time from CLOCK_MONOTONIC)
  • header.frame_id: frame name; default imu_link
  • linear_acceleration: accelerometer axes in m/s²
  • angular_velocity: gyroscope axes in rad/s
  • orientation: not provided; quaternion is always (0,0,0,1)
  • Covariance: accelerometer and gyroscope diagonal variances computed from bandwidth and noise density; orientation covariance set to -1 (unknown)
  Tip

  Change the topic name with the imu_topic parameter or ROS 2 remapping.

Services

Two std_srvs/srv/Trigger services control acquisition at runtime:

Service (default)	Function
~/enable	Enable IMU data acquisition (start interrupt thread)
~/disable	Pause IMU data acquisition (stop interrupt thread)

Tip

Configure service names with enable_service_name and disable_service_name.

Configurable Parameters

All parameters below can be set in the launch file or on the command line. They are read at startup and cannot be changed at runtime:

Parameter	Type	Default	Description
frame_id	string	imu_link	Frame ID in IMU messages
fuse_by	string	accel	Fusion reference sensor: accel or gyro
max_age_ns	int	50000000	Max interpolation time gap in nanoseconds; recommend ≥ 3× ODR period
publish_rate	double	0.0	Fixed publish rate in Hz; 0.0 = publish as data arrives
auto_start	bool	true	Start acquisition automatically on node launch
imu_topic	string	rdkimu/data	IMU data topic name
enable_service_name	string	~/enable	Enable service name
disable_service_name	string	~/disable	Disable service name
accel_bwp	string	NORMAL	Accelerometer filter mode: OSR4, OSR2, or NORMAL
accel_odr	string	400	Accelerometer ODR: 12_5, 25, …, 1600
accel_range	string	24G	Accelerometer range: 3G, 6G, 12G, 24G
gyro_range	string	2000DPS	Gyroscope range: 125DPS ~ 2000DPS
gyro_bandwidth	string	ODR400_BW47	Gyroscope bandwidth, e.g. ODR2000_BW532 (see enum)
accel_drdy_int	string	INT1	Accelerometer interrupt pin: INT1 or INT2
accel_int_gpio_mode	string	PP_H	Accelerometer interrupt GPIO mode: PP_H, PP_L, OD_H, OD_L
gyro_drdy_int	string	INT3	Gyroscope interrupt pin: INT3 or INT4
gyro_int_gpio_mode	string	PP_H	Gyroscope interrupt GPIO mode; same values as above
accel_drdy_gpio_chip	int	4	SoC accelerometer interrupt GPIO chip
accel_drdy_gpio_line	int	2	SoC accelerometer interrupt GPIO line
gyro_drdy_gpio_chip	int	3	SoC gyroscope interrupt GPIO chip
gyro_drdy_gpio_line	int	12	SoC gyroscope interrupt GPIO line
fifo_length	int	256	Software FIFO length (frames)
fifo_mode	string	OVERWRITE	FIFO full policy: DROP or OVERWRITE
irq_priority	int	-1	Interrupt thread real-time priority (-1 = auto)
irq_thread_timeout_ns	int	1000000000	Interrupt thread wait timeout in nanoseconds

Sensor parameters map 1:1 to C API rdk_imu_config_t; see C API Reference.

Usage Examples

View live data:

ros2 topic echo /rdkimu/data
ros2 topic hz /rdkimu/data

Pause/resume acquisition:

ros2 service call /rdk_imu_node/enable std_srvs/srv/Trigger
ros2 service call /rdk_imu_node/disable std_srvs/srv/Trigger

Launch with custom parameters (e.g. topic name and rate):

ros2 launch rdk_imu_module rdk_imu.launch.py imu_topic:=/my_imu publish_rate:=200.0