Author: Pito Salas

Gemeral

• An excellent and very detailed troubleshooting guide for the Raspberry Pi

LED on the Red Board

• Blinking green is the “starting up” indication.

• Solid green is the “ready” indication.*

• Solid yellow is the “low battery” caution indication.

• Solid red is the “low battery” warning.

• Blinking red is the “shutting down” indication.

• Blinking purple is (AFAIK) the “I don’t know what is going on” indication, but I could be wrong.

But, note that all of these indications are only valid when using a Dexter Industries / Modular Robotics operating system. (i.e. Raspbian for Robots, GoPiGo OS, or Dexter OS). It will continue to blink green when using any other O/S. The Minirover configuration is Ubuntu! Also see: https://www.dexterindustries.com/GoPiGo/get-started-with-the-gopigo3-raspberry-pi-robot/2-connect-to-the-gopigo-3/

Python default

To Change the default python on ubuntu (assuming you want it to be python3.4)

sudo update-alternatives --install /usr/bin/python python /usr/bin/python3.4 1

Check whether spi is working on the pi

>>> import spidev
>>> spi = spidev.SpiDev()
>>> spi.open(0,1)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
PermissionError: [Errno 13] Permission denied

MiniRover is our modification of the GoPiGo3 robot. It comes with software, a VPN and all kinds of fancy things which is why I decided to give it a special name. This page is under construction as I troubleshoot and make notes about things. I expect feedback from everyone where the instructions don't meet reality!

This section will help you get your robot set up to go. Note that if you received this from the Autonomous Robotics Lab then part of these steps may already be done.

See the important information about turning the robot on and off here: Using the Robot.

MicroSD Card (if needed)

If your robot was set up by us, then you should skip this step!

You are going to load software onto the microSD Card - which will wipe out what you loaded onto it according the the instructions before. We provide you a disk image on which to store it. It changes from time to time. This link is to a google folder that will contain the versions. You should use the latest one in that folder. I recommend you use the app "Balena Etcher" to copy the image onto your microSD card.

To create a new MicroSD from the old one, see Backup Raspi Card on MacOS

Connecting to the network

Now we are facing a dilemma. We need to get the robot on your network. There are several ways of doing this. Below are two specific scenarios that we support:

1. A usb keyboard, usb mouse and a HDMI display and eduroam wifi access

2. OR A network cable and non-eduroam wifi access

3. A MiniRover v2 and non-eduroam wifi access. It should be labeled with a name.

Scenario 1

1. We will tell you what the name of your robot is. Plug it in below wherever you see gopigo3

2. Locate a wired network connection (on your router for example) and use a network cable to connect your robot to the network

3. Now turn the power on (see Using MiniRoverfor instructions. It should boot up into linux. But you won't know this because there's no keyboard or screen!

4. Using your own computer or development environment that is attached to the network check that you see the robot. This includes a linux computer where you program, or a browser web development environment. Broadly speaking, it's the computer "other than" to raspberry pi on the robot (we will refer to this as the remote computer from now on).

ping gopigo3.local

Once this works you know that you have access to the robot from your remote computer. Make note of the robot' ip address. It will likely look like 192.168.1.xx but not necessarily.

1. Now use ssh (secure shell) to get to the robot from the remote:

ssh pi@gopigo3.local

It will ask you for the password for account pi. It is raspberry. Once you get in you are 1/2 way there!

1. Now we want to get your robot onto your local wifi network. You need to know the wifi network's name and password. On the robot command line type:

sudo nmcli d wifi connect <SSID> password <password>

Where <SSID> is the network's name. You can surround it in quotes if there are spaces or other funny characters. is the password.

1. Next shutdown the robot nicely (see above), disconnect the network cable, and start the robot up nicely again (see above.)

2. Once it's back, follow the same steps to ssh pi@gopigo3.local and enter the password raspberry and you should have a wireless enabled robot.

Scenario 2

1. Connect your mouse, keyboard and screen to the Raspberry pi. You will find several free USB ports and an HDMI port. Look closely they are all there.

2. Boot up the Raspberry Pi and wait until it is running and you see the desktop

3. Locate the network settings dialog box by clicking the network icon on the top right

4. Add eduroam as a network, and fill it in as follows:

1. Finally shutdown the robot, unplug the keyboard, mouse and monitor and reboot

2. Once it's back ssh pi@gopigo3.local and enter the password raspberry and you should have a wireless enabled robot

Scenario 3 incomplete and incorrect

You've received a fully set up and tested Minrover v2, and you know the name. The following steps are written as if the robot is called mr1. Scenario 3 Robots will have the account ubuntu with the password ubuntu (so different from scenario 1 and 2)

1. Now turn the power on (see Using MiniRoverfor instructions. It should boot up into linux. But you won't know this because there's no keyboard or screen!

2. MiniRover will come up as a Wifi access point. The SSID is mr1XXXX where XXXX is part of the MAC address. The wifi password is robotseverywhere.s Connect to it via your computer's wifi.

Troubleshooting ssh gopigo3.local

Under certain circumstances gopigo3.local will be found. If so you need to find out the ip address of your robot when it is on wifi (not wired). If then this should work:

ssh pi@<ip address>

Updating the hostname of your Robot

Rename the hostname of your robot. It comes to you called "gopigo3" but they are all called that and this can cause confusion. Let's say you want to call your robot pitosalas. Oddly you have to change it in two places. Here's how"

# In the shell of the robot:
sudo hostname pitosalas

# In the hostname file:
sudo nano /etc/hostname

Now the robot is called pitosalas and at least it will be different from other miniRovers.

Eduroam

On eduroam it is often automatically known as gopigo3.dyn.brandeis.edu. So after rebooting it check if this works. It's not guaranteed but often it works just fine.

VPN

You can run everything on the robot itself but it doesn't have a screen. You could plug an external screen, keyboard and mouse and have a complete ROS enabled computer (the robot) at your finger-tips. But it would be real slow. So instead we are going to add the robot to a "VPN" - virtual private network which will allow you to work with it remotely.

1. Prepare the VPM configuration by:

sudo apt-get remove -y tailscale
sudo rm -rf /var/lib/tailscale/tailscaled.state

# Reboot right after!
sudo reboot

1. Setup VPN

# Get the tskey from Pito
cd ~/rosutils
chmod +x pi_connect.sh

# Run the script with the tailscale authkey
sudo ./pi_connect.sh <tskey-123abc456>

# On successful connect, you should see this
# Connected. IP address: 100.xx.xxx.xxx

1. myvpnip should now return that same IP address.

Updates for your Robot

We have installed some Brandeis specific software which should be updated:

cd ~/rosutils
git pull
cp ~/rosutils/bashrc_template.bash ~/.bashrc
cd ~/catkin_ws/src/gpg_bran4
git pull

And then edit the new ~/.bashrc according to the instructions in the file.

Updates to your Cloud Desktop

1. Check that you have ~/rosutils directory on your cloud desktop. If not:

cd
git clone https://github.com/campusrover/rosutils.git
cp rosutils/bashrc_template.bash .bashrc

Edit .bashrc according to the instructions in it

This will continue to be updated

Turning it on

It is important that you follow a rigid procedure when turning the robot on and off.

Assuming it is totally off:

1. Make sure the battery pack is correctly connected to the robot.

2. Switch on the battery pack

3. Click the micro button on the red board

1. Look at the Raspberry Pi (not the "red board") You will see tiny red and green LEDs blinking. Wait until the green one has settled down to slow flickering.

Turning it off

1. From your ssh command line on the remote computer, type sudo shutdown now

2. Once the Raspberry Pi has stopped blinking you can turn off the power switch on the battery pack.

Charging the Battery

The Battery pack came with a charger. It has a light on which is red while charging and green when fully charged. Note that the battery will not charge when its switch is set to off.

rset command

We've implemented a very simple tool to set up the IP addresses correctly. It will be changing as I figure out how to make it better. So for now...

1. If you have a cloud desktop and want to run simulations without a actual miniRover" rset cloud

2. If you have a cloud desktop add a real robot, run rset robot on your cloud desktop and rset pi on the actual miniRover (over ssh)

3. If you have a local docker based desktop, run rset docker there.

rset by itself displays the current status

(I know a combination is missing and plan a revision of this)

Starting the MiniRover ROS applications

Note that all we run on the MiniRover itself are roscore, and the nodes needed for the motors, lidar and camera. Everything else runs on your "remote". The following commands are to be done on the MiniRover from ~/catkin_ws

# launch the motor controller and lidar
roslaunch minirover mr_bringup.launch

# launch camera (optional if you need the camera)
roslaunch gpg_bran raspicam.launch

Web Desktop tools

Note that this includes all flavors, cloud based, local docker based, and gpu based browser desktops. If you just want to use the simulators on their own and are not using an actual miniRover, then: rset cloud is enough. At that point you can run your ROS programs.

There are numerous scripts, programs and launch files that are preinstalled on your ROS wegpgb desktop. I will document only some of them here but you can look around and find more that are interesting. All of them from the book are here. I have not renamed any of them for that reason.

# Fun prr examples
rosrun prrexamples red_light_green_light.py
rosrun prrexamples wander.py

# Visualize robot with rviz
roslaunch gopigo3_navigation gopigo3_rviz.launch 

# Or with gazebo (not as useful)
roslaunch gopigo3_navigation gopigo3_gazebo.launch 

# Run different simulated stages to experiment with roslaunch 
roslaunch turtlebot3_gazebo turtlebot3_stage_1.launch
roslaunch turtlebot3_gazebo turtlebot3_stage_2.launch
roslaunch turtlebot3_gazebo turtlebot3_stage_3.launch
roslaunch turtlebot3_gazebo turtlebot3_stage_4.launch

# Control the robot
roslaunch turtlebot3_teleop turtlebot3_teleop_key.launch

# Begin building the map on real robot
roslaunch gopigo3_navigation gopigo3_slam.launch

# Begin localization with AMCL
roslaunch gopigo3_navigation amcl.launch

Rset Command

In order to facilitate working in all the combinations of environments we have these commands:

• rset pi - declare that this is the raspberry pi

• rset cloud - declare that this is a cloud desktop working with sim

• rset robot - declare that this is a cloud desktop working with a real robot

• rset - display settings

Aliases

There are a bunch of handy aliases:

• myip - this computer's regular local ip

• myvpnip - this computer's vpn ip if it has one

• stopnow - immediately stop the robot

• teleop - run a simple teleop tool

• ru - connect to rosutils

• cm - catkin_make

• cw - cd ~/catkin_ws

• cs - cd ~/catkin_ws/src

Accounts and passwords

• miniRover

  • hostname gopigo3

  • default account pi

  • default password raspberry

• Cloud or Docker Desktop

  • default password dev@ros

  • desktop: url: http://vnc..ros.campusrover.org

  • vscode: http://code..ros.campusrover.org

Key Environment Variables

ROS_MASTER_URI=http:/100.94.206.80:11311 (example!) should always be set to the computer where roscore is running. If you are using a physical robot, then roscore runs on the robot itself. If you are in the web deskop and working just with simulation then roscore would run there.

Robot

ROS_MASTER_URI = robot's own ip address ROS_IP = robot's own ip address

Remote Computer

ROS_MASTER_URI = robots ip address ROS_IP = remote computer's own IP address

These IP addresses are on different networks and cannot access each other. So instead we've created what is called a "virtual private network" that connects them together. Both your robot and your cloud desktop have an alternate ip address which they can both see.

IP Addresseses

• myip returns your local ip address

• myvpnip returns your vpn ip address (if you have one)

GoPiGo3 Basic Kit

We recommend that you start with a . Build it following the instructions. There is a lot written and a lot to google about it. Here are some useful links:

• - where you can get many questions answered

• - where you find step by step instructions.

• - instructions for students taking Cosi119a at Brandeis University to order a miniRover.

In addition to what you received with the Basic Kit you will need the following to get through the instructions.

• A Raspberry Pi 3+

• A battery pack (with Y-cable and charger)

• A MicroSD card

• A Lidar

• A very short USB cable

The Battery pack is different from what the instructions talk about. The Y-Cable is used to connect the barrel connector of the battery pack with the corresponding battery connector on the "Red Board" which in turn will power the Raspberry Pi.

The robot will come with a microSD card with the dexter software. There is some very very simple calibration that you need to do.

Battery Pack

• The battery pack is specific in terms of voltage and capacity. Don't substitute it for another one.

• Note that the battery pack needs to be in the "on" position in order to have the charger do anything. And obviously it has to be in "ON" for the robot to work.

• It also comes with a charger and a y-cable. The y-cable is about 10" long and has three barrel connectors on it in a y-configuration.

• We use only two of the 3 ends of the Y-connector. One goes into the barrel connector on the red board, and one goes into the barrel connector on the battery pack.

• We then connect the very short usb cable with one end in the battery pack and the other end in the "power" connection of the Lidar board. The Lidar board is tiny about 1.5" square. On the one side you have the funny Lidar wires and on the other side you have two micro usb connectors. If you look very carefully one is marked data and one is marked power. The one marked data is connected with a short usb cable to one of the usb connectors of the pi. The one marked power is connected with another short usb cable to the battery pack.

Camera

Lidar

The Lidar needs to be mounted on the top plexiglass part. You will need to drill two holes. Make sure that the Lidar is exactly centered and pointed forward. As far as the drilling: I kept it to a minimum and drilled only two. I think it doesn't matter much. Mostly that it be straight and centered. Note that the narrower part of the Lidar is the front. You want it centered and facing forward (which on the other side of the ball caster.) I drilled holes for the two posts at the back of the Lidar (the wider part.) I don't see that it matters much though, that was what was easiest for me.