ros2_gremsy: gSDK based Gremsy Gimbal Driver Node for ROS2

A ROS2 interface to control Gremsy gimbals. Based on the Gremsy/gSDK interface, Flova/ros_gremsy , and the MavLink protocol.

Disclaimer: This software package is not officially developed by or related to Gremsy.

Description

This package utilizes UART communication with gimbal COM port to control the gimbal.

The Gremsy gimbals using MavLink protocol for message format and gSDK provides necessary functions for communication.

This package is only tested with Gremsy MIO and ROS2 Galactic so far. Feel free to contribute if you have another model working with this package, or if there are some modifications needed for it.

Setup

Clone this repository to src folder of your workspace. --recurse-submodules flag will automatically clone the required gSDK submodule.

git clone --recurse-submodules https://github.com/tiiuae/ros2_gremsy

Install dependencies using rosdep from the workspace directory, modify ${ROS_DISTRO} if you have in your environment.

rosdep install -y -r -q --from-paths src --ignore-src --rosdistro ${ROS_DISTRO}

Run the colcon to build package.

colcon build --symlink-install

Check the device name of the gimbal by running the following command.

dmesg | grep tty

The default com_port parameter is already /dev/ttyUSB0. If the device name is different, you should add it to run command. The launch file is not created yet, so you should manually enter it to the command.

ros2 run ros2_gremsy gremsy_node --ros-args -p com_port:=/dev/ttyUSB0

Run with docker image

The default com_port parameter is already /dev/ttyUSB0. If the device name is different, you should use the correct one to mount the device. For example, --device /dev/ttyUSB1:/dev/ttyUSB0, so host ttyUSB1 is mounted to container as ttyUSB0.

docker run --rm -ti --env DRONE_DEVICE_ID=sad99 --network host --device /dev/ttyUSB0:/dev/ttyUSB0 ghcr.io/tiiuae/tii-gremsy:main

Cannot open serial port error

By default, the ubuntu user does not have access to the serial port. You can add it by

sudo usermod -a -G tty ${USER}
sudo usermod -a -G dialout ${USER}

Reboot the computer.

Published Topics

Topic name	Type	Description
~/imu	sensor_msgs/Imu	IMU data
~/encoder	geometry_msgs/Vector3Stamped	Encoder data
~/mount_orientation_global	geometry_msgs/QuaternionStamped	Orientation of the gimbal in the global frame
~/mount_orientation_local	geometry_msgs/QuaternionStamped	Orientation of the gimbal in the local frame

Subscribed Topics

Topic name	Type	Description
~/gimbal_goal	geometry_msgs/Vector3Stamped	Goal orientation of the gimbal in the global frame in radians. X->Roll, Y->Pitch, Z->Yaw
~/gimbal_goal_quaternion	geometry_msgs/QuaternionStamped	Goal orientation of the gimbal in the local frame as quaternion.

Services

Service name	Service type	Input type	Output types	Description
~/lock_mode	std_srvs/SetBool	bool data	bool success, string message	Change gimbal mode: lock mode (true) and follow mode (false)

Parameters

Parameter name	Type	Description	Accepted values	Default value
device_id	integer	Device id- 0: MIO, 1: S1, 2: T3V3, 3: T7	0,1,2,3	0
com_port	string	Serial device for the gimbal connection	-	/dev/ttyUSB0
baudrate	integer	Baudrate for the gimbal connection	-	115200
state_poll_rate	double	Rate in which the gimbal data is polled and published	0.0-300.0	50.0
goal_push_rate	double	Rate in which the gimbal are pushed to the gimbal	0.0-300.0	60.0
gimbal_mode	integer	Control mode of the gimbal 0:GIMBAL_OFF, 1:LOCK_MODE, 2:FOLLOW_MODE	0,1,2	1
tilt_axis_input_mode	integer	Input mode of the gimbals tilt, 0:CTRL_ANGLE_BODY_FRAME, 1: CTRL_ANGULAR_RATE, 2:CTRL_ANGLE_ABSOLUTE_FRAME	0,1,2	2
tilt_axis_stabilize	boolean	Input mode of the gimbals tilt	-	true
roll_axis_input_mode	integer	Input mode of the gimbals roll, 0:CTRL_ANGLE_BODY_FRAME, 1:CTRL_ANGULAR_RATE, 2:CTRL_ANGLE_ABSOLUTE_FRAME	0,1,2	2
roll_axis_stabilize	boolean	Input mode of the gimbals roll	-	true
pan_axis_input_mode	integer	Input mode of the gimbals pan, 0:CTRL_ANGLE_BODY_FRAME, 1:CTRL_ANGULAR_RATE, 2:CTRL_ANGLE_ABSOLUTE_FRAME	0,1,2	2
pan_axis_stabilize	boolean	Input mode of the gimbals pan	-	true
lock_yaw_to_vehicle	boolean	Uses the yaw relative to the gimbal mount to prevent drift issues. Only a light stabilization is applied.	-	true

Note: Only Gimbal Pixy and T3V3 support CTRL_ANGLE_BODY_FRAME mode with pitch and yaw axis.

TODO:

• Create a launch file and parameters file for the package.
• Verify other models working with this package
• Add TF publishing
• Add other topics for controlling gimbal.

References

gSDK Flova/ros_gremsy