RPLIDAR A3M1

RPLIDAR A3M1 is a 360 degree 2D LIDAR developed by SLAMTECH. It can perform 2D 360-degree scan within a 25 meter range and generates 2D point cloud data that can be used in mapping, localization and environment modeling. It is based on laser triangulation ranging principle. It supports to work under two modes: enhanced modes and outdoor modes. The enhanced mode of RPLIDAR is being used in our Racecar project for point cloud visualization and object detection.

Sample Point Data Information

During working process, the RPLIDAR will oputput the sampling data and each sample point data contains the information as mentioned in the foloowing table:

RPLIDAR Sample Point Data Information

Data Type	Unit	Description
Distance	mm	Current measured distance value between the rotating core of the LIDAR and the sampling point.
Heading	degree	Heading angle of the measurement
Start Flag	Bool	Flag of new scan
Checksum		Checksum of LIDAR return data.

Measurement Performance Specification

RPLIDAR Performance Specification

Item	Enhanced Mode	Outdoor Mode
Operating Range	White object: 25 meters, Black Object: 10 meters	White object: 20 meters, Black Object: TBD
Minimum Operating Range	0.2m	0.2m
Sample Rate	16 kHz	16 kHz or 10 kHz
Scan Rate	Typical value: 10 Hz (adjustable between 5 Hz - 15 Hz)	Typical value: 10 Hz (adjustable between 5 Hz - 15 Hz)
Angular Resolution	0.225 degree	0.225 degree or 0.36 degree
Communication Interface	TTL UART
Communication Speed	256000 bps

Coordinate System Definition of Scanning Data

The RPLIDAR uses a left-hand coordinate system. The x-axis is directly ahead of the sensor, and origin is the rotating center of the range scanner core. The rotation angle increases in clockwise direction. The deatailed is shown in figure below:

Communication Interface

It uses separate 5V DC power for powering the range scanner core and the motor system using XH2.54-5P male socket. The details interface is illustrated in the figure and the description of the same can be found in the table below:

RPLIDAR External Interface Signal Definition

Color	Signal Name	Type	Description	Min	Typical	Max
Red	VCC	Power	Total Power	4.9V	5V	5.2V
Yellow	TX	Output	Serial port output of the scanner core	0V	3.3V	3.5V
Green	RX	Input	Serial port input of the scanner core	0V	0V	0V
Black	GND	Power	GND	0V	0V	0V
Blue	MOTOCTL	Input	Scan motor / PWM Control Signal	0V	3.3V	5V

Serial Port Interface Specification

RPLIDAR Serial Port Interface Specification

Item	Unit	Min	Typical	Max	Comments
Band Rate	bps		256000
Working Mode			8N1		8n1
Output high voltage	Volt (V)	2.9		3.5	Logic High
Output low voltage	Volt (V)			0.4	Logic Low
Input high voltage	Volt (V)	1.6		3.5	Logic High
Input Low voltage	Volt (V)	-0.3		0.4	Logic Low

Specification for PWM Signal of MOTOCTL

The roatting speed for the motor of LIDAR is controlled via MOTOCTL which is supplied using PWM signal with special frequency and the speed of the motor is decided by the duty cycle of the input MOTOCTL PWM Signal. The rerquirements for the input PWM Signal of MOTOCTL is described in the table below:

RPLIDAR Specification for PWM Signal of MOTOCTL

Item	Unit	Min	Typical	Max	Comments
High Level Voltage	V	3.0	3.3	5
PWM Frequency	Hz	24,500	25,000	25,000	Square Signal
Duty Cycle Range		0%	60%	100%	Typical value is the duty cycle of high pulse wodth when the scannner frequency is at 10Hz