This package aims to automate parameter handling within ROS 2. The build script automatically generates a c++ struct from a yaml file input. The generated struct contains all parameters as nested fields. Addtional methods are generated, which enable parameter updating.
You must include the gen_param_struct pakcage in your cmake project.
find_package(gen_param_struct REQUIRED)
You then need call the generate_param_struct_header function with the following arguments:
TARGET # target that depends on generated struct
OUT_DIR # output directory for generated struct
YAML_FILE # path to yaml file
mkdir colcon_ws
mkdir colcon_ws/src
cd colcon_ws/src
git clone https://github.com/pac48/gen_param_struct.git
cd ..
colcon build
source install/setup.bash
ros2 run gen_param_struct_example test_node --ros-args --params-file src/gen_param_struct_example/include/config/implementation.yaml
You should see an output like this:
[INFO] [1656018676.015816509] [admittance_controller]: Control frame is: 'ee_link'
Run the following:
ros2 param list
You should see:
/admittance_controller:
admittance.damping_ratio
admittance.mass
admittance.selected_axes
admittance.stiffness
chainable_command_interfaces
command_interfaces
control.frame.external
control.frame.id
enable_parameter_update_without_reactivation
fixed_world_frame.frame.external
fixed_world_frame.frame.id
ft_sensor.frame.external
ft_sensor.frame.id
ft_sensor.name
gravity_compensation.CoG.force
gravity_compensation.CoG.pos
gravity_compensation.frame.external
gravity_compensation.frame.id
joints
kinematics.base
kinematics.plugin_name
kinematics.tip
qos_overrides./parameter_events.publisher.depth
qos_overrides./parameter_events.publisher.durability
qos_overrides./parameter_events.publisher.history
qos_overrides./parameter_events.publisher.reliability
state_interfaces
use_sim_time
All parametter are automatically declared and callbacks are setup by default. You can set a parameter by typing:
ros2 param set /admittance_controller control.frame.id new_frame
You should see:
[INFO] [1656019001.515820371] [admittance_controller]: Control frame is: 'new_frame'
Congratulations, you updated the parameter!
If you try to set a parameter that is read only, you will get an error. Running the follwing
ros2 param set /admittance_controller joints ["joint_new"]
will result in the error
Setting parameter failed: parameter 'joints' cannot be set because it is read-only
Running the follwing
ros2 param describe /admittance_controller admittance.damping_ratio
will show a parameter's description
Parameter name: admittance.damping_ratio
Type: double array
Description: specifies damping ratio values for x, y, z, rx, ry, and rz used in the admittance calculation. The values are calculated as damping can be used instead: zeta = D / (2 * sqrt( M * S ))
Constraints:
Min value: 0.1
Max value: 10.0
If you try to set a value out of the specified bounds,
ros2 param set /admittance_controller admittance.damping_ratio [-10.0,-10.0,-10.0,-10.0,-10.0,-10.0]
you will get the error
Setting parameter failed: Invalid value for parameter admittance.damping_ratio. Value not within required bounds.
If you try to set a vector parameter with the wrong length,
ros2 param set /admittance_controller admittance.damping_ratio [1.0,1.0,1.0]
you will get the error
Setting parameter failed: Invalid size for vector parameter admittance.damping_ratio. Expected 6 got 3
If you try to load a yaml file with missing required parameters
ros2 run gen_param_struct_example test_node --ros-args --params-file src/gen_param_struct/gen_param_struct_example/include/config/missing_required.yaml
you will get the error
terminate called after throwing an instance of 'rclcpp::exceptions::ParameterUninitializedException'
what(): parameter 'joints' is not initialized
[ros2run]: Aborted
A sample generated file is located here: https://github.com/pac48/gen_param_struct/blob/main/gen_param_struct_example/include/config/admittance_controller.h