lidar-scan

Simple and cross-platform tool for grabbing data from RPLIDAR A3A1 scanner. Based on lidar-visualizations.

Gallery

Video: https://www.youtube.com/watch?v=MQhYTqz40xI

Indoor – walking around the house:

Outdoor near street – passing cars can be seen:

Outdoor – lots of trees and shrubs around:

About RPLIDAR

This project has been created with the low-cost Slamtec RPLIDAR A3M1 device, and SDK provided by its manufacturers. We haven't tested it, but should be compatible with other related Slamtec models. A3M1 supports two important scanning modes depending on a scanning environment (indoor/outdoor).

Property	A3M1
Distance Range	up to 25 m
Sample Rate	up to 16 kHz
Scan Rate	5 Hz - 20 Hz
Angular Resolution	up to 0.225°
Communication Interface	TTL UART
Communication Speed	256000 bps

The complete RPLIDAR specification and documentation is available below:

• A3M1 website
• SDK GitHub
• RPLIDAR A3 User Manual
• RPLIDAR A3 Introduction and Datasheet

RPLIDAR Modes

RPLIDAR supports several scanning modes which differs by its application (indoor/outdoor), distance range, and sample rate. More details can be found in the documentation of the product. You should only consider the option 3 and 4, because the first three ones are here due to compatibility reasons and don't produce spectacular results.

ID	Scan mode	Sample time [us]	Frequency
0	Standard	252	0.484406
1	Express	126	0.968812
2	Boost	63	1.93762
3	Sensitivity	63	1.93762
4	Stability	100	1.2207

RPLIDAR software RPM vs actual RPM

Software RPM	Actual RPM	Software RPS	Actual RPS	Error
200	196.62426442087457	3.33...	3.2770710736812427	~1.7%
400	432.0221331536197	6.66...	7.200368885893662	~8.0%
600	684.5153998304605	10.00	11.408589997174342	~14.0%
800	965.1414495782639	13.33...	16.085690826304397	~20.6%
1000	1268.981667825387	16.66...	21.14969446375645	~26.8%

RPM to RPS:

RPM = (1 / 360_CLOUD_TIME) * 60

Usage

lidar-scan port [options]

Options

-h --help       Print this message
-m --mode       RPLIDAR mode (0 - 4)
-r --rpm        RPLIDAR revolutions* per minute (200 - 1023)
--reset         Try to reset the RPLIDAR driver and exit

* the actual rpm might differ.

Point cloud output

Output contains a series of point clouds. Each line (except for comments which must start with #) represents a single point which consists of an angle value [°] and a distance value [mm]. Both may be a floating point number, and have to be separated by any kind of white characters. Lines starting with ! separates two point clouds. Each line marked with ! should consist of the ID number of the following point cloud and number of milliseconds elapsed from grabbing the previous one. Clouds should be sorted by their ID number.

Example:

! 0 0
120  100
240  100
360  100
! 1 500
120  200
240  200
360  200
! 2 500
120  300
240  300
360  300
! 3 500

Compilation

Linux, macOS

1. Install rplidar_sdk:

   $ ./install_rplidar

2. Build:

   $ make

3. Run:

   $ ./lidar-scan

4. Install (Optional):

   $ make install

Windows (Visual Studio)

1. Make sure you have the prerequisites:

   • Visual Studio with C++ toolchain. visualstudio.microsoft.com/
   • RPLIDAR SDK - github.com/Slamtec/rplidar_sdk.

2. Prepare RPLIDAR SDK:

   • Move the directory containing RPLIDAR SDK to the path of this repository. Rename it to rplidar-sdk.

   • Install CP2102 driver which allows communicating via USB and UART: rplidar_sdk/tools/cp2102_driver.

   • Open VS solution with SDK: rplidar_sdk/sdk/workspaces/vc**/sdk_and_demo.sln.

   • Compile rplidar_driver in Debug and Release mode. This will create two .lib files which will be used in our final app. You can find them here: rplidar_sdk\sdk\output. These files will be automatically found by the LV project, so don't move them.

   • That's it. SDK is ready and you can close the VS project.

3. Build:

   • Open the VS solution of lidar-visualizations - lidar/lidar.sln.
   • Compile in Debug or Release mode.

Thanks

This project was developed within Electronics and Computer Science Club in Knurów (KNEI for short) where lots of amazing projects and ideas come from. Have a look at our website - https://knei.pl/ - unfortunately, at the moment, only available in Polish. Check out our GitHub too - https://github.com/knei-knurow.

Numerous packages with colourful electronic gadgets like RPLIDAR have been granted to us by our friends from KAMAMI.pl.