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Lightware LW20 Product Manual

Lidar sensor
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Features:
•
Small size laser rangefinder when weight and size are critical
•
Long range measurements up to 100 meters to sense remote objects
•
Up to 388 readings per second for fast detection of obstacles
•
IP67 enclosure prevents damage from water and dust
•
Built-in drivers to make a scanning LiDAR by adding a digital servo
•
Encoded laser pulses prevent interference for other lasers
•
First and last return signals are available to suit your application
•
Power saving mode to save energy when not in use.
LW20 / SF20 LiDAR - Product manual - Revision 2
eters to sense remote objects
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© LightWare Optoelectronics (Pty) Ltd, 2017
LW20 / SF20 LiDAR sensor
Product manual
The
compact
LiDAR sensor
for drones,
autonomous vehicles
and robots
|
www.lightware.co.za

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Summary of Contents for Lightware LW20

  • Page 1 • First and last return signals are available to suit your application • Power saving mode to save energy when not in use. LW20 / SF20 LiDAR - Product manual - Revision 2 © LightWare Optoelectronics (Pty) Ltd, 2017 www.lightware.co.za...

  • Page 2: Table Of Contents

    Information found in this document is used entirely at the reader’s own risk and whilst every effort has been made to ensure its validity, neither LightWare Optoelectronics (Pty) Ltd nor its representatives make any warranties with respect the accuracy of the information contained herein.

  • Page 3: Overview Of The Lw20

    The LW20 is also available as an open frame module for OEMs using part code SF20. 2. What can the LW20 do? The LW20 can be used as an altimeter on multi-copter drones to measure the exact height above ground level or to set off alarms when the ground gets too close.

  • Page 4: What Are The Main Characteristics Of The Lw20

    LW20 / SF20 LiDAR sensor Product manual Used on autonomous vehicles, the LW20 can be a forwards looking obstacle sensor or can be used to create “SLAM” maps to aid in navigation. Figure 3 :: Autonomous vehicle navigation What’s your application? 3.

  • Page 5: Specifications Of The Lw20 / Sf20

    LW20 / SF20 LiDAR sensor Product manual The LW20 is able to measure the first and last return signals when there is more than one object in the laser beam. Measuring the distance to the nearest object and the furthest object allows a drone to get information about potential collisions with trees while simultaneously following the terrain at a known height above ground.

  • Page 6: How To Communicate With The Lw20 Using The Graphical Interface

    5. How to communicate with the LW20 using the graphical interface To use the graphical interface to setup and test the LW20 you will need to connect the serial port of the LW20 to the USB port on a PC. This is done using a serial-to-usb converter such as the TTL-232R-3V3-WE converter cable from FTDI (http://www.ftdichip.com/ Products/Cables/USBTTLSerial.htm).

  • Page 7: Figure 6 :: The Graphical Interface Home Screen

    LW20 / SF20 LiDAR sensor Product manual There are four tabs at the top of the home screen. Each one provides a visualization of the settings inside the LW20 and guides you through the setup process as follows: The “Home” tab shows the welcome screen with shortcuts to other screens shown near the bottom •...

  • Page 8: Figure 8 :: The Graphical Interface Parameters Screen

    LiDAR scanning. Figure 9 :: The graphical interface Operate screen LW20 / SF20 LiDAR - Product manual - Revision 2 © LightWare Optoelectronics (Pty) Ltd, 2017 www.lightware.co.za...

  • Page 9: How To Communicate With The Lw20 Using A Terminal Emulator

    6. How to communicate with the LW20 using a terminal emulator To use a terminal emulation application to setup and test the LW20 you will need to connect the serial port of the LW20 to the USB port on a PC. This is done using a serial-to-usb converter such as the TTL-232R-3V3-WE converter cable from FTDI (http:// www.ftdichip.com/Products/Cables/USBTTLSerial.htm).

  • Page 10: Figure 12 :: Arrangement Of Screens In Terminal Emulation Mode

    Product manual Pressing the “ESC” key switches the LW20 into human-to-machine mode providing data and menus in an easy to read format. You can navigate between the menus and live data streams using the arrow keys. There are four screens available, two show the LW20 setup and two show the setup of the servo if it is attached.

  • Page 11: Figure 13 :: Connection To A Devantech Usb-Iss Module

    The I2C interface is designed for machine-to-machine communications with multiple devices over a small network. In order to test the I2C interface on the LW20 an I2C to USB converter can be connected and a limited number of commands can be sent to the LW20 using the LightWare Terminal application.

  • Page 12: Figure 16 :: I2C Test Dialog Box Showing Command Buttons

    Once the correct setting is applied, commands can be sent and results viewed by selecting the “I2C Tester” icon and pressing the one of the test buttons available in the dialog box. Figure 16 :: I2C test dialog box showing command buttons LW20 / SF20 LiDAR - Product manual - Revision 2 © LightWare Optoelectronics (Pty) Ltd, 2017 www.lightware.co.za...

  • Page 13: How To Communicate With The Lw20 Using A Controller

    The serial port is a one-to-one protocol that lets a single LW20 talk to a single host controller. The serial interface uses 3.3 V logic to transmit results and receive commands. 5 V logic should also work without any level shifters.

  • Page 14: How To Do An Initial Setup Of The Lw20

    8. How to do an initial setup of the LW20 Using the GUI, Terminal or machine commands the measuring characteristics of the LW20 can be tailored to suit different applications. The primary settings can be found by pressing the “Laser” button under the “Setup” tab of the GUI or on the main menu screen of the terminal.

  • Page 15: How To Set Up A Scanning Lidar Using A Digital Servo

    LW20 and servo power supplies. Communications to the LW20 and the servo can be made through either the serial port or via an I2C bus depending upon the model of the LW20. In this guide we will use the serial port and the GUI interface to set up the servo parameters and configure automatic scanning.

  • Page 16: Figure 20 :: Setting The Servo's Limits Of Motion Using The Pwm Values

    Note that settings will only be saved to the LW20 once the “Save” button in the bottom left corner of the screen has been pushed. Once the electrical characteristics of the servo have been entered using the method above, the servo can be used to aim the LW20 in a specific direction or autonomously scan the LW20 to produce LiDAR maps and provide collision warning alarms.

  • Page 17: Figure 22 :: Setting Up The Servo's Scanning Characteristics

    Figure 22 :: Setting up the servo’s scanning characteristics The speed of the scan is determined by how fast the LW20 updates and the number of steps that the servo moves with each reading. The “Steps per reading” box increases or decreases this speed as does the update rate setting in the “Laser” section. Running the servo faster increases its power consumption but provides a faster response to changes in measurements.

  • Page 18: Figure 24 :: Reducing The Field Of View To Avoid Detecting The Landing Legs On A Drone

    Switching from bi-directional to uni-direction scans is done using the “Scan type” selection box. Figure 25 :: Uni-directional scanning for higher precision LW20 / SF20 LiDAR - Product manual - Revision 2 © LightWare Optoelectronics (Pty) Ltd, 2017 www.lightware.co.za...

  • Page 19: How To Set Up The Alarms

    10. How to set up the alarms The LW20 has two alarms, A and B, that be can used to warn when objects get too close. The alarm changes from a 0 state to a 1 state when an object is detected closer than the set distance. The alarms are updated every time a new distance measurement is taken.

  • Page 20: Instructions For Safe Use

    No regular maintenance is required for the LW20 but if the lenses start to collect dust then they may be wiped with suitable lens cleaning materials. Make sure that the LW20 is switched OFF before looking into the lenses.

  • Page 21: Appendix B :: Cables

    Ferrite Core 40 OHM Solid 1.5mm LightWare Optoelectronics (Pty) Ltd LA 000_096: LW/SF20 I2C & power cable Rev: 2 Figure 31 :: I2C and power cable LW20 / SF20 LiDAR - Product manual - Revision 2 © LightWare Optoelectronics (Pty) Ltd, 2017 www.lightware.co.za...

  • Page 22: Appendix C :: Complete Command Set For Machine-To-Machine Communications

    Appendix C :: Complete command set for machine-to-machine communications The LW20 has either a serial or an I2C communication port depending upon which model number is ordered. Commands can be sent that read values, change settings or alter the performance of the LW20. Distances are in meters and temperatures in degrees celsius.
  • Page 23 Read the us per degree scale of the servo #SWS,10.00 sws:10.00 Change the us per degree scale of the servo: Adjustment range = 0.1 … 1000.0 LW20 / SF20 LiDAR - Product manual - Revision 2 © LightWare Optoelectronics (Pty) Ltd, 2017 www.lightware.co.za...
  • Page 24 0 = power off 1 = power on Legacy commands for the serial port D’ or ‘d’ 78.32 Output the current distance once only LW20 / SF20 LiDAR - Product manual - Revision 2 © LightWare Optoelectronics (Pty) Ltd, 2017 www.lightware.co.za...

  • Page 25: Revision History

    Authors Comments Rev 2 2017/04/10 Include new section “6.1 How to communicate with the LW20 using the Devantech USB to I2C module” (pages 11, 12). Rev 1 2017/03/03 Updated “4. Specifications of the LW20 / SF20” to include the approval “FDA: 1710193-000 (2017/02)”...

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