Notes on robotics, vision, and systems.
In C++, a class's member variables and member functions are stored separately, and only non-static member variables belong to objects of the class. Each non-static member function has only one function instance, meaning that multiple objects of the same type share one block of code. How does the code distinguish which object invoked it? This is where the this pointer comes in.
Every object needs initial setup and cleanup before it is destroyed. Object initialization and cleanup are two very important safety concerns. Using an object or variable without an initial state has unknown consequences; failing to clean up an object or variable in time after use can also cause safety issues.
Encapsulation combines attributes and behaviors into a whole to represent real-world entities, while controlling access to those attributes and behaviors. When designing a class, attributes and behaviors are written together to represent an entity. The syntax is as follows.
In C++, parameters in a function's parameter list can have default values. If an argument is passed to a parameter, the supplied value is used; otherwise, the default value is used. However, if a parameter at a given position has a default argument, every parameter after it must also have a default value.
Rviz is a three-dimensional visualization tool that is highly compatible with robot platforms based on the ROS software framework. Rviz can graphically display robot sensor data, robot motion status, environmental information, and more.
The functions of a laubch file are as follows: it configures and starts multiple nodes through an XML file. It can also start ROS Master automatically (so there is no need to run roscore separately).
The TF package manages all coordinate frames. It keeps a ten-second history of the relationships among all frames and can show where a grasped object is relative to the robot's center frame.
Each time the Client makes one Request, the Server sends data once. The data format is personal information such as name, gender, and so on.
ROS Master includes a Parameter Server, which is a global dictionary that stores configuration parameters. These configuration parameters are globally accessible to all nodes.
Send a service request programmatically. In other words, the client sends a request to the server to spawn a turtle, and the server returns the response to the client. Go back to the catkin_ws/src directory and create a package named learning_service.
