GUI controls as ROS 2 rqt plugin

Motivation

Hi, I have been using PyBullet in my engineering thesis and recently noticed that you have made the ROS-PyBullet Interface code available. I was very comfortable using Pybullet, but at the time I was surprised why it was not available as a ROS package. I see that the ROS 2 branch is in early development, so I decided to add something from myself.

Description

I took care of the GUI implementation in the form of the rqt plugin. The reference point for me was the rpbi_controls_node.py file from main branch of ros_pybullet_interface repository.

When the Start, Step, or Stop button is pressed, an attempt is made to connect to the corresponding service server. The GUI code using the tkinter library used the get_srv_handler() function from the custom_ros_tools package. I created an analogous function so as not to immediately rewrite the entire custom_ros_tools repository to ROS 2.
Pressing the Send button does nothing. This is because the value of the robot_name parameter is used when handling the press event of this button. In ROS 2 the concept of parameters has been completely changed. There is no global parameter anymore. Each parameter is specific to a node. This issue requires careful consideration.

Screenshot

How to run

In the root of your workspace build ros_pybullet_rqt_plugin package and source setup file.
```
colcon build --packages-select ros_pybullet_rqt_plugin
. install/setup.bash
```
Refresh rqt cache memory to make the plugin visible (details can be found here)
```
rqt --force-discover
```
You can run the GUI in one of three ways:
- Open rqt (use rqt command) and navigate to Plugins :arrow_right: Introspection :arrow_right: PyBullet Interface Controls
- Start only this plugin using -s (standalone) flag
```
rqt -s ros_pybullet_rqt_plugin
```
- Open GUI as a ROS 2 node:
```
ros2 run ros_pybullet_rqt_plugin ros_pybullet_rqt_plugin 
```

My setup

Ubuntu 22.04
ROS 2 Humble Hawksbill
Python 3.10.6

Tools used in the development

Qt 5 Designer - I used this tool to design the graphical interface of the plugin

How to test

You can test whether the status information is displayed correctly by publishing a message on the rpbi/status topic.

ros2 topic pub /rpbi/status -1 std_msgs/msg/Int64 "{data: 1}"

ros-pybullet / ros_pybullet_interface