Linorobot in Action

Build a linorobot from scratch

This is a document project describe how to build a linorobot from scratch.

Table of content

• Introduction
• Hardware
• Hardware test and driver installation
• Software
• Debug&test
• FAQ
• Update Notes
• Useful links

Introduction

This github project is describe how to build a Linorobot from scratch. Includeing hardware, software, debug and test.

Linorobot is a suite of Open Source ROS compatible robots that aims to provide students, developers, and researchers a low-cost platform in creating new exciting applications on top of ROS. More about Linorobot can be found here

Author of this project: jack.wang a fullstack engneree focus on software, robots and autonomous vehicle.

Hardware

In this part, I will tell how to build hardware part about linorobot. Including Hardware and how to assemble them together.

Hardware list

Here is the hardware list that I used, all of this part can be found at Taobao or Amazon

• Laser sensors:

  RPLIDAR-A1 @Taobao

  RPLiDAR-X4 @Amazon

• IMU:

  GY-85 @Taobao

  GY-85 @Amazon

• Micro-controller:

  Teensy 3.6 @Taobao

  Teensy 3.6 @Amazon

• Ubuntu install ARM based dev board:

  Raspberry Pi 3/B+ @Taobao

  Raspberry Pi 3/B+ @Amazon

• Motor Drivers:

  BTS7960 @Taobao

  BTS7960 @Amazon

• Motor and Wheels:

  Homemade chassis @Taobao

  Homemade chassis @Amazon

• connecting wires:

  Dupont Line @Taobao

  Dupont Line @Amazon

More supported hardware can be found here

Assemble

// Todo

Hardware test and driver installation

In this section, I will show you how to make sure hardware works well, and install the required drivers.

Laser sensor

PRLiDar A1

RPLIDAR A1 contains a range scanner system and a motor system. After power on each sub-system, RPLIDAR A1 start rotating and scanning clockwise. User can get range scan data through the communication interface (Serial port/USB).

Reference from RPLiDAR datasheet

Hardware test

1. Assemble PRLiDAR A1 with drive board .

2. Find a Micro USB-B Line, connect drive board to your computer

3. Then LiDAR should start rotating clockwise.

   

Driver installation (MacOS)

1. Install serial port driver

   Driver installation file can be found at CP210x USB to UART Bridge VCP Drivers

2. Download SDK from github

   git clone [email protected]:Slamtec/rplidar_sdk.git

3. Complie SDK

   Make sure you have g++ installed and run:

   cd rplidar_sdk_v1.9.0_1/sdk && make

   After compile, directory output/Darwin/Release should be generated. And you can find:

   • simple_grabber

     This demo application simply connects to an RPLIDAR device and outputs the scan data to the console.

   • ultra_simple

     This demo application grabs two round of scan data and shows the range data as histogram in the command line mode.

4. Find USB serial:

   ls -l /dev/tty.*

   If you see /dev/tty.SLAB_USBtoUART That means driver is work:

   

5. Run simple_grabber

   In directory: rplidar_sdk_v1.9.0_1/sdk/output/Darwin/Release

   ./ultra_simple /dev/tty.SLAB_USBtoUART

   You should see something like this:

   Ultra simple LIDAR data grabber for RPLIDAR.
   Version: 1.9.0
   RPLIDAR S/N: 52989AF0C5E29DD2B6E39DF5D14B3116
   Firmware Ver: 1.24
   Hardware Rev: 5
   RPLidar health status : 0
   *WARN* YOU ARE USING DEPRECATED API: grabScanData(), PLEASE MOVE TO grabScanDataHq()
   *WARN* YOU ARE USING DEPRECATED API: ascendScanData(rplidar_response_measurement_node_t*, size_t), PLEASE MOVE TO ascendScanData(rplidar_response_measurement_node_hq_t*, size_t)
      theta: 0.55 Dist: 00898.00 Q: 47
      theta: 1.59 Dist: 00000.00 Q: 0
      theta: 2.14 Dist: 00000.00 Q: 0
      theta: 2.67 Dist: 00000.00 Q: 0
      theta: 3.22 Dist: 00000.00 Q: 0
      theta: 3.75 Dist: 00000.00 Q: 0
      theta: 4.30 Dist: 00000.00 Q: 0
      theta: 4.83 Dist: 00000.00 Q: 0
      theta: 7.00 Dist: 00000.00 Q: 0
      theta: 7.53 Dist: 00000.00 Q: 0
      theta: 8.08 Dist: 00000.00 Q: 0
      theta: 8.61 Dist: 00000.00 Q: 0
      theta: 9.16 Dist: 00000.00 Q: 0
      theta: 9.69 Dist: 00000.00 Q: 0
      theta: 10.23 Dist: 00000.00 Q: 0
      theta: 10.77 Dist: 00000.00 Q: 0
   

Software

In this part, I will introduce how to install ROS on Respberry Pi. After that, linorobot Installation will be shown step by step.

Install OS for Raspberry Pi

Usually, I use Ubuntu 16.04 for ROS, but after read this document: Installing ROS Kinetic on the Raspberry Pi. I directly install pre-installed Ros Ubuntu image offer by Ubiquity, which can be found here.

Install steps:

1. Download img file for Respberry Pi: Img Link

2. Use Etcher to write image to Respberry Pi SD card:

   1. Select Image

   2. Select Drive

   3. Flash

   4. Validating

      If everything is OK, you should see this:

      

3. Insert in your TF card to Respberry Pi. Power on, And wait some time (in 3 mins)

4. Open Wifi config page to find a new Wifi point named: ubiquityrobotXXXX where XXXX is part of the MAC address. The wifi password is robotseverywhere.

5. After connected, use ssh [email protected] with a password ubuntu to login.

If everything is OK you should see this:

And ros is installed:

Make your Respberry Pi connect to internet

To install needed software, we need to make Respberry Pi connect to internet.

On Mac OS, use share network to share a internet connection to Respberry Pi is very simple. Here is the way:

1. Connect Mac to a AP with internet. (Note: Please Do NOT use 802.1x wifi AP)

2. Connect Respberry Pi to Mac with a network line.

3. Open System Settings-> Share : , and config like show bellow:

   

4. Open a terminal, run: arp -a to find all host on same AP, find the host marked as bridge

   

5. ssh [email protected]

6. Test network status: ping baidu.com

   

If everything is OK, your Respberry Pi will connect to internet.

Linorobot Installation

In this section, I will show how to install linorobot on Respberry Pi.

1. Login in to your Respberry Pi:

   ssh [email protected]

2. clone the install package:

   git clone https://github.com/linorobot/lino_install
   cd lino_install

3. For Raspberry Pis it is recommended to have a swap file to prevent the initial build from failing. You can disable this once the installation is done.

   sudo apt-get install dphys-swapfile

4. Run install script, where base in( 2wd, 4wd, ackermann, mecanum) and sensor in( xv11, rplidar, ydlidar, hokuyo, kinect, realsense). I am use 2wd base and rplidar, so run:

5. ./install 2wd rplidar
   

   Then, you will see this:

   armv7l
   
   ______ _____________   _________ ________ _______ ________ _______  
   ___  / ____  _/___  | / /__  __ \___  __ \__  __ \___  __ )__  __ \___  
   __  /   __  /  __   |/ / _  / / /__  /_/ /_  / / /__  __  |_  / / /__  /
   _  /_____/ /   _  /|  /  / /_/ / _  _, _/ / /_/ / _  /_/ / / /_/ / _  /
   /_____//___/   /_/ |_/   \____/  /_/ |_|  \____/  /_____/  \____/  /_/
   
                               http://linorobot.org
   
   
   You are installing ROS-kinetic Linorobot for 2wd base with a rplidar sensor. Enter [y] to continue.

   Entry y

6. Wait to finish, (It takes me more than 30 mins, so be patient)

Some issue you maybe face:

• unsupported locale setting , try this
• fatal error: lino_msgs/PID.h: No such file or directory, rerun install script several times.

Update Notes

• 2018-10-10 Add Hardware test and driver installation include laser sensor
• 2018-10-12 Add Make your Respberry Pi connect to internet and Linorobot Installation

Useful links

• Linorobot home page: https://linorobot.org
• Linorobot getting stated: https://github.com/linorobot/linorobot/wiki/1.-Getting-Started#11-what-you-need
• Ros home page: http://ros.org
• Respberry Help page: https://www.raspberrypi.org/help/
• Ubiquityrobotics home page: https://ubiquityrobotics.com/
• INTRODUCING THE TEENSY 3.5 AND 3.6: https://hackaday.com/2016/08/17/introducing-the-teensy-3-5-and-3-6/
• PRLiDAR A1 Download page: https://www.slamtec.com/en/Support#rplidar-a1
• PRLiDAR SDK: https://github.com/slamtec/rplidar_sdk
• PRLiDAR ROS: https://github.com/slamtec/rplidar_ros