ROS 2 C++ package for controlling a pan-tilt mechanism using Joy messages. The pan-tilt mechanism uses two Waveshare ST3215 serial bus servo motors. It is also compatible with the Feetech STS3215 and Waveshare ST3215-HS motors.

The mechanism contains a bracket for attaching any payload using a custom mount (Fusion360 file available in the meshes directory). A standard tripod mount is also provided. Note: This package is solely for controlling the pan-tilt mechanism and does not contain nodes for attached payloads.

• pan_tilt_cmd: This executable (pan_tilt_cmd_node.cpp converts Joy messages to JointState messages using one or more joystick axes each for the pan and tilt movements. Here, pan and tilt are controlled using the right joystick's horizontal and vertical movements. The configuration (config/cmd_config.yaml) allows up to 2 axes per joint, which are then mixed in the source code.
• pan_tilt_ctrl: This executable (pan_tilt_ctrl_node.cpp) subscribes to JointState messages which are used to control the motors, and Joy messages to determine the status of the emergency stop. When the emergency stop button is pressed, the torque is disabled on both motors, allowing the user to move the motors by hand. When the button is pressed again, the motors return to the position specified by the pan and tilt axes - which can be defined in the configuration file (config/ctrl_config.yaml). This node uses the SCServo_Linux library to drive the motors in Mode 0 (closed-loop servo). This node also publishes measured JointState values and DiagnosticArray messages using PWM, motion - true/false, temperature, voltage, and current measurements for each motor.
• pan_tilt_launch.py: This is the launch file that launches pan_tilt_cmd and pan_tilt_ctrl nodes, and loads parameters using their respective configuration files.

pan_tilt_cmd: The following parameters and default values are defined in the source code. The default values are overwritten by config/cmd_config.yaml.

• joint_names: Joint names for the pan and tilt joints (Default: [pan_joint, tilt_joint])
• joint_inv: Invert joint direction (Default: [false, false])
• joy_axes0: Joystick axes mapping for index 0 of joint_names (Default: [2, 5])
• joy_axes1: Joystick axes mapping for index 1 of joint_names (Default: [7])
• mid_pos: Middle (origin) step values for the pan and tilt motors (Default: [2048, 2048])
• min_pos: Lower limit step values for the pan and tilt motors (Default: [1600, 1600])
• max_pos: Upper limit step values for the pan and tilt motors (Default: [2816, 2816])

pan_tilt_ctrl: The following parameters and default values are defined in the source code. The default values are overwritten by config/ctrl_config.yaml.

• joint_ids: Motor IDs for each joint (Default: [1, 2])
• stop_button: Button mapping for the emergency stop functionality (Default: 4)
• speed: Speed of the motors in steps per second ranging from -4500 to 4500 (Default: 4500)
• acceleration: Acceleration of the motors ranging from 0 to 255 (Default: 255)
• usb_port: USB port name (Default: /dev/ttyACM0)
• baud_rate: Baud rate of the motor driver (Default: 1000000)

• Clone this repository in your ROS 2 workspace
• Navigate to the repository and run: git submodule init && git submodule update
• If needed, build the SCServo_Linux library by running: cd include/SCServoLinux && cmake . && make
• Check the *_config.yaml files in the config directory, and make any necessary changes
• If needed, configure the mid-point of the motors using examples in include/SCServoLinux or the Feetech Debugger
• Build the package and run the launch file: ros2 launch pan_tilt_ros pan_tilt_launch.py
• On a separate terminal, launch your joystick node. In this case, the joystick_drivers package is used.