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LTU-Actor Core

This is the main package of the LTU-Actor autonomous vehicle platform. It has the other packages in this organizations as submodules to track the version used with this version of Core.

Getting Started

Ubuntu 16.04 (ROS Kinetic) only ships with version 4.x, and we need significantly newer to run the webpage. This is the official nodejs ppa.

curl -sL https://deb.nodesource.com/setup_10.x | sudo -E bash -

This command can be used to clone all Actor packages that will be used:

git clone https://github.com/LTU-Actor/Core.git
git clone https://github.com/LTU-Actor/AdapParameter.git
git clone https://github.com/LTU-Actor/InputProcess-CamAdjust.git
git clone https://github.com/LTU-Actor/Route-Blob.git
git clone https://github.com/LTU-Actor/Route-Obstacle.git
git clone https://github.com/LTU-Actor/Route-Pothole.git
git clone https://github.com/LTU-Actor/Route-Spline.git
git clone https://github.com/LTU-Actor/Route-StopSign.git
git clone https://github.com/LTU-Actor/Route-Waypoint.git

Run rosdep to install all dependencies (including nodejs).

rosdep install --from-paths src --ignore-src -r -y

And compile with catkin isolated.

catkin_make_isolated

Running

The rosbridge (webpage ros api), video server (webpage access to video topics), router (main node), and simple webpage with:

roslaunch ltu_actor_core core.launch

then view the page http://localhost:3000/

Example Launchfile

<launch>
  <include file="$(ltu_actor_core)/launch/core.launch">
    <arg name="rosbridge_port" value="8090" />
    <arg name="http_video_port" value="8091" />
    <arg name="script_folder" value="$HOME" />
    <arg name="estop_service" value="/estop/estop" />
    <arg name="vehicle_enable_service" default="/vehicle/enable" />
    <arg name="navsatfix_topic" value="/navsatfix" />

    <arg name="video1" default="/video1" />
    <arg name="video2" default="/video2" />
    <arg name="video3" default="/video3" />
    <arg name="video4" default="/video4" />
  </include>
</launch>

Using the web app

The above image is taken from the Actor system running with one of the recordings from the Vehicle-GEM package. Scripts built for the Actor GEM are also commited to the Vehicle-GEM/routes/ folder.

UI Parts:

  • Four video topics are displayed as configured in the launch file arguments
  • The "Route HB" or heartbeat toggles true/false when the heartbeat() script function is called, signaling that the route script is still running. In order for this to work, the route script must ensure that the function is called within every long loop.
  • Route Index and Route Distance are updated by the info_* functions, and are used in routes to display various status numbers (e.g. the distance to the next waypoint and the waypoint number).
  • estop state manual boolean shows if the manual estop buttons are pressed. This is assumed to be std_msgs/Bool on /estop/state, or configured as a launch file argument.
  • All the following information pertains directly to the selection, control, and modification of route scripts:
    • The main textbox shows the currently loaded route. This may either be a file stored on the actor computer, or the modified version in ram only.
    • The reload arrow will re-sync the browser to the route server incase another browser has made a change, or the system has been re-loaded.
    • The dropdown menu will show all files in the configured routes/ folder. Selecting one will load and begin running that route, destroying any non-saved changes to the current route. Selecting a new route will also trigger a software estop.
    • The save button will send any changes to the textbox to the route server, save them to the file, apply the changes, begin running the route, and trigger a software estop.
    • The load button will reload the route from the file selected in the dropdown menu. Any changes in memory will be destroyed. The file contents will be sent back to the browser, the origional route will begin running, and a software estop is triggered.
    • The apply button will send the contents of the browser to the route server, and run them without saving them to disk. A software estop will be triggered.
    • The estop button will trigger a software estop.
    • The resume button is the only way to clear a software estop, and allow a non-zero command to be sent to the drive-by-wire system.

Example course

An example of the course this router has been used for can be seen below. A video of the functions demonstrated on this course is in the docs folder here

The route:

The route scripts are written in Lua, and have access to a handful of custom functions/variables bound from the router host. In addition, the host will execute the setup.lua file when each Lua script's environment is initalized. The lua state is rebuilt before each script is started.

The script below is an example of the flexability of the scripting language. It instructs the vehicle to follow a list of waypoints using the Route-Waypoint package.

wps = {
  {lat=42.474577731988404, lon=-83.24978459935954}, -- after long
  {lat=42.474443020559235, lon=-83.24961630603279}, -- 3 shield
  {lat=42.4743747342588,   lon=-83.24948869708074}, -- rusty stick
  {lat=42.47435906661956,  lon=-83.24932813838758}, -- sidewalk
  {lat=42.4743974394603,   lon=-83.24915945160514}, -- tree 5
  {lat=42.47448536517313,  lon=-83.24899809469223}, -- tree 2
  {lat=42.47457155453122,  lon=-83.24888768798787}, -- exit curve
  {lat=42.47462683972605,  lon=-83.24875816602247}, -- charles tree
  {lat=42.474935949391856, lon=-83.24834024117531}  -- fire hydrant
}

local wp = 1

send_topic("/waypoint/cmd")
while wps[wp] ~= nil do
  heartbeat()
  pub_latlong(wps[wp].lat, wps[wp].lon, "/waypoint/waypoint")
  local d = dist(wps[wp].lat, wps[wp].lon)

  -- show on webpage
  info_distance(d)
  info_index(wp)

  if d < 1.0 then wp = wp + 1 end
  spin_for(100)
end

The route can be seen doing the following things:

  • Maintaining state for the next waypoint with the wp variable
  • Instruct the router to forward the vehicle commands from the Route-Waypoint output topic with send_topic("/waypoint/cmd"). Forwarded topics are expected to be geometry_msgs/Twist in the standard format (linear.x and angular.z for car control). This topic will be forwarded until the send_topic function is called again, or until the script exits.
  • In the loop, the heartbeat function is called to notify the webpage that it is still running.
  • pub_latlong is a function bound into the Lua state by the router. It publishs to a subscriber that is known to communicate with the Route-Waypoint node. This publisher is created on the first call to this function.
  • the info_* functions display status information to the webpage. In this instance, they are the current waypoint target's index, and the distance to it.
  • The loop swaps to the next waypoint when the vehicle is within one meter of the target. dist() is another custom function, which in this case if created in the setup script. It returns the distance of the vehicle to a lat/long in meters.
  • spin_for is simmilar to a sleep(ms) call, but will allow ROS to spin in the meantime. spin_once can be called to call ros::spinOnce without delay. This function must be called repeatedly in order for the router to continue functioning.

Many of the custom functions and variabled can be seen in the comment at the top of the default route:

--[[
  heartbeat()                           toggle the heartbeat status topic to show the route is running
  spin_once()                           allow ROS topics/services to be serviced
  spin_for(int ms)                      delay for milliseconds while also servicing ROS
  send(float linear, float angular)     continuously send cmd commands (forward/reverse & steering)
  send_topic(string topic)              continuously forward a Twist topic as for cmd instead of constants
  dist(double lat, double long)         get the distance in meters from the gps point
  last_float32(string topic)            get the value of a topic (replace Float32 with any std_msgs type)
  pub_float32(string topic, float val)  oppisite of above, publish on a topic
  info_index(int i)                     show an int "index" on the webpage
  info_distance(float d)                show a float "distance" on the wepbage
  vehicle_enable()                      enable the drive-by-wire
  estop()                               trigger an estop
]]--


while true
do
  send(0.0, 0.0)
  heartbeat()
  spin_for(500)
end