Demos
This GitHub Repository provides templates for the development of ros2_control-enabled robots and a simple simulations to demonstrate and prove ros2_control concepts.
If you want to have a rather step by step manual how to do things with ros2_control
checkout ros-control/roscon2022_workshop repository.
What you can find in this repository
This repository demonstrates the following ros2_control
concepts:
Creating a
HardwareInterface
for a System, Sensor, and Actuator.Creating a robot description in the form of URDF files.
Loading the configuration and starting a robot using launch files.
Control of a differential mobile base DiffBot.
Control of two joints of RRBot.
Implementing a controller switching strategy for a robot.
Using joint limits and transmission concepts in
ros2_control
.
Goals
The repository has two other goals:
Implements the example configuration described in the
ros-controls/roadmap
repository file components_architecture_and_urdf_examples.The repository is a validation environment for
ros2_control
concepts, which can only be tested during run-time (e.g., execution of controllers by the controller manager, communication between robot hardware and controllers).
Example Overview
- Example 1: RRBot
RRBot - or ‘’Revolute-Revolute Manipulator Robot’’ - a simple position controlled robot with one hardware interface. This example also demonstrates the switching between different controllers.
- Example 2: DiffBot
DiffBot, or ‘’Differential Mobile Robot’’, is a simple mobile base with differential drive. The robot is basically a box moving according to differential drive kinematics.
- Example 3: “RRBot with multiple interfaces”
RRBot with multiple interfaces.
- Example 4: “Industrial robot with integrated sensor”
RRBot with an integrated sensor.
- Example 5: “Industrial Robots with externally connected sensor”
RRBot with an externally connected sensor.
- Example 6: “Modular Robots with separate communication to each actuator”
The example shows how to implement robot hardware with separate communication to each actuator.
- Example 8: “Using transmissions”
RRBot with an exposed transmission interface.
Quick Hints
These are some quick hints, especially for those coming from a ROS1 control background:
There are now three categories of hardware components: Sensor, Actuator, and System. Sensor is for individual sensors; Actuator is for individual actuators; System is for any combination of multiple sensors/actuators. You could think of a Sensor as read-only. All components are used as plugins and therefore exported using
PLUGINLIB_EXPORT_CLASS
macro.ros(1)_control only allowed three hardware interface types: position, velocity, and effort. ros2_control allows you to create any interface type by defining a custom string. For example, you might define a
position_in_degrees
or atemperature
interface. The most common (position, velocity, acceleration, effort) are already defined as constants in hardware_interface/types/hardware_interface_type_values.hpp.Joint names in <ros2_control> tags in the URDF must be compatible with the controller’s configuration.
In ros2_control, all parameters for the driver are specified in the URDF. The ros2_control framework uses the <ros2_control> tag in the URDF.
Joint names in <ros2_control> tags in the URDF must be compatible with the controller’s configuration.