Скачать или смотреть How to Get Real-time Lidar Data from ROS on Raspberry Pi Using Python

Discover how to effectively retrieve real-time Lidar data using a Python script with ROS on a Raspberry Pi. Easy step-by-step guide included.
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How to Get Real-time Lidar Data from ROS on Raspberry Pi Using Python

If you're utilizing a Raspberry Pi for robotics projects, particularly with a LaserScanner setup that combines a motor and a rangefinder, you may have found it necessary to retrieve real-time data efficiently. Here we will tackle how to achieve this, focusing specifically on accessing real-time Lidar data from a ROS (Robot Operating System) environment using Python.

Understanding the Problem

You are operating a Rangefinder via ROS and have set up multiple terminal windows to run the necessary components:

roscore – This is the main server that manages communication between nodes.

rosrun urg_node urg_node – This node subscribes to the Lidar data coming from the rangefinder.

A shell script invoking rostopic echo /scan – This captures and saves the Lidar data to a file (lidar.txt) until you close the scripting terminal.

Your aim now is to bypass manual terminal use and instead fetch this data in real time within a Python script, making the entire process much more efficient.

The Solution: Using Python to Access Lidar Data in Real-Time

To retrieve the data in real-time, you can create a Python script that subscribes to the /scan topic. This allows you to process and manipulate Lidar data as it streams in. Below are the steps to guide you through writing this Python script.

Step 1: Setting Up Your Environment

Before we jump into coding, ensure that you have all the necessary libraries and packages installed:

ROS (with the required packages for Python).

sensor_msgs: This is where the Lidar's LaserScan message is defined.

Step 2: Writing the Python Script

Here’s a basic template for your test.py file that will achieve your goal:

[[See Video to Reveal this Text or Code Snippet]]

Step 3: Running Your Script

To execute your Python script and start receiving data:

Open a terminal window.

Run the command roscore to start the ROS master.

Open another terminal, run the command for your Lidar node to collect the data as usual.

Finally, run your Python script using python test.py.

Conclusion

By following these steps, you will be able to retrieve Lidar data from your Raspberry Pi setup in real-time using Python. This method streamlines your operations and enables you to process data on-the-fly, enhancing your robotics projects and experiments.

Remember, experimenting with modifications to the callback function allows further processing of the Lidar data according to your specific needs. Happy coding!