Hitachi-LG LDS Lidar

How to use the Hitachi-LG LDS Lidar robot skill

NMS Driver for the Hitachi-LG LDS 360 degree lidar. This robot skill connects to the Lidar and pushes the data into ARC's NMS (navigation messaging system) to be used with level 1 navigation viewers. Read the NMS manual page to understand how this skill can be used.



Screenshot




Configuration



1) BaudRate
The baud rate for the communication. 

2) Offset Degrees
Correct the angle that the lidar is mounted

3) Advanced communication parsing
Include debug information in the log window. This is only recommended if asked by Synthiam to help debug a communication issue. Otherwise, this will use a lot of resources.

4) Set variables with location data
If you're not using the NMS, check this, and global variables will be created for the scan data.

5) Fake NMS Pose hint event
The Better Navigator can use the Hector SLAM pose hint, which will not require a pose sensor. You can enable this option if you have The Better Navigator configured to use Hector as the pose hint. This will send a "fake" pose hint of 0,0 to the NMS so that the pose event will run after every lidar scan.

NMS (Navigation Messaging System)

This skill operates in Level #3 Group #1. It publishes obstacle detection to the NMS. While some SLAM systems will attempt to determine the cartesian position of the robot without telemetry, it is best to combine this skill with a Group #2 sensor. 

How to Use EZ-LIDAR SLAM

Program the LIDAR in Blockly
Like all Synthiam controls, the Blockly programming language can be used. In this example below, the robot will speak when an object has come close to it. It will also speak the degrees of where the object was. To see this program in action, click HERE.




Variables
In the configuration menu of this control, you can view the variables that this skill creates. The variables hold the most recent values of minimum/maximum distance, degrees, and running status of the lidar.

Arduino Sketch

There are two ways to connect to this lidar. You can either use a standard USB<->UART convertor, such as those found on amazon or eBay. Or you can use a 32u4 based Arduino board (i.e. Micro) to make your own USB<->UART converter. The 32u4 based boards are necessary Arduino versions to use because they support emulating USB HID devices, such as a Serial device. 

Here is a simple sketch that can be used on a 32u4 based board...

Code:

void setup() {
  
   Serial1.begin(230400); // Init Hardware Serial port on pins 0 and 1
   Serial.begin(230400);  // Init Serial Port
}

void loop() {
  
  if (Serial.available()) 
    Serial1.write(Serial.read());
  
  if (Serial1.available())
    Serial.write(Serial1.read());  
}

Wiring

GREY - Ground
RED - +5
GREEN - RX (connects to TX on Arduino or USB Converter)
BROWN - TX (connects to RX on Arduino or USB converter)

Robotis USB <-> UART Converter

The Robotis version of this sensor may include their USB UART converter, which uses a CP210x chipset. The driver for windows can be found by clicking here: CP210x_Windows_Drivers.zip

Videos

Real-time SLAM mapping


Room Mapping


Near Object Detection

Resources

The source files for the hardware can be found here: github.com/synthiam/E-41_LIDAR