/simple_mobile_robot

Primary LanguageC++BSD 3-Clause "New" or "Revised" LicenseBSD-3-Clause

Simple Mobile Robot

A ROS package for a simple two wheel drive robot.

Build Badge

Tested on ROS Indigo and ROS Kinetic.

Dependencies

Packages that are not shipped with ros-desktop-full installation are listed here (based on Ubuntu 14.04 or 16.04):

catkin_simple: only available as source code, need to clone into your workspace

amcl: binary installation package available on both Indigo and Kinetic

map_server: binary installation package available on both Indigo and Kinetic

gazebo_ros_control: required to simulate lidar sensor and diff wheel drive controller

twist_mux: binary installation package available on both Indigo and Kinetic

interactive_marker_twist_server: binary installation package available on both Indigo and Kinetic

robot_state_publisher: binary installation package available on both Indigo and Kinetic

Usage

Make sure you have ROS Indigo or ROS Kinetic and all the required dependency installed.

Clone this repository into your workspace and do catkin_make:

roscd && cd src
git clone https://github.com/TuZZiX/simple_mobile_robot.git
roscd && catkin_make

Launch files

Robot in starting pen

To spawn the robot in a starting pen:

roslaunch simple_mobile_robot robot_in_pen.launch

Following arguments are supported:

  • move: default is none
    Select way to control the mobile robot, options:
        [none] - do nothing
        [keyboard] - control the robot by WASD key
        [square] - run a square path, specify the side length by extra argument [length], e.g. [length:=3.0]
        [circle] - run a circular path, specify the diameter by extra argument [length], e.g. [length:=3.0]
  • length: default is 3.0
    The length of the path when moving the robot in square or circle mode, see argument move definition for detail.
  • rviz: default is true <-- turn this off if you don't want rviz
    Start rviz and interactive marker to control the robot.
  • amcl: default is true
    Load map and start AMCL for localization, for now, this is only for making the view in rviz looks better.

    Also, if you found your computer is slow, try to turn this off.
  • lidar: default is true
    Start lidar E-stop node to prevent the robot from hitting anything.

After running this launch file, you can run other nodes to command the robot.

The launch file also supports specify command by launcher arguments, e.g. if you want to run keyboard teleop to command the robot, do:

roslaunch simple_mobile_robot robot_in_pen.launch move:=keyboard

It will wait a short period for Gazebo to finish loading and then start the move.

Here is a demo of using this launch file and ways to interact with the robot: https://youtu.be/B8IkBJNDmC8

Empty world

To start the robot in an empty world:

roslaunch simple_mobile_robot simple_mobile_robot.launch

Following arguments are supported:

  • move: default is none
    Select way to control the mobile robot, options:
        [none] - do nothing
        [keyboard] - control the robot by WASD key
        [square] - run a square path, specify the side length by extra argument [length], e.g. [length:=3.0]
        [circle] - run a circular path, specify the diameter by extra argument [length], e.g. [length:=3.0]
  • length: default is 3.0
    Length of the path when moving the robot in square or circle mode, see argument move definition for detail
  • rviz: default is true <-- turn this off if you don't want rviz
    Start rviz and interactive marker to control the robot.

After running this launch file, you can run other nodes to command the robot.

The launch file also supports specify command by launcher arguments, e.g. if you want to do a circle move with diameter = 3.0 in clockwise, do:

roslaunch simple_mobile_robot simple_mobile_robot.launch move:=circle length:=3

It will wait a short period for Gazebo to finish loading and then start the move.

Here is a demo of using this launch file and ways to interact with the robot: https://youtu.be/vKvUAmQZhHI

Nodes

After the launch file finishes loading, you can start the following nodes to command the robot.

Keyboard teleop

As this robot needs a smooth speed profile, so I implement my own cubic speed controller. With an intuitive way to control just like playing racing games

Run:

rosrun simple_mobile_robot keyboard_controller

Parameters can be change in parameters.yaml

# keyboard teleop
KEY_TIMEOUT: 0.4    # continue moving for a short period after key released, also to prevent key jitter, in second
STOP_DEACC: 1.5     # when key released, instead of using max acceleration, use a slower deceleration to simulate inertia
MAX_ACC: 3.0        # max acceleration on speed in m/s^2 to start and stop
MAX_SPIN_ACC: 2.4
ACC_JERK: 10.0      # max acceleration jerk for both MAX_ACC and MAX_SPIN_ACC in m/s^3 or rad/s^3
MAX_SPEED: 1.0      # max speed in m/s
MAX_SPIN_RATE: 0.8  # max spinning rate in rad/s
UPDATE_RATE: 100    # control loop running frequency, in hz

Notice: If you want to use other teleop packages, you need to remap /cmd_vel to /extra_vel to avoid conflict with other command velocity source.

For demo video, see the demo for launch files.

Square move

Keep looping a square path with open loop control.

Run:

rosrun simple_mobile_robot square_move [length]

[length] is the side length of the square path in meter, if you want the robot to move counter-clockwise, specify a negative number

Example: rosrun simple_mobile_robot square_move 3, run a clockwise square path of length = 3

Video: https://youtu.be/boI3VW1YflU

This video also shows how to passing different arguments into launch file to select functionality

Circle move

Keep looping a circle path with open loop control.

Run:

rosrun simple_mobile_robot circle_move [diameter]

[diameter] is the diameter of the circular path in meter, if you want the robot to move counter-clockwise, specify a negative number

Example: rosrun simple_mobile_robot circle_move 5, this run a clockwise circular path of diameter = 5

Speed can be change in parameters.yaml, by changing MAX_SPEED.

Video: https://youtu.be/zx1Ngz1CBWU

This video also shows cmd_vel overriding.

LIDAR safety stop

A feature to prevent the robot from hitting the wall, it will force the robot to stop when too close to obstacles.

It publishes lidar_alarm_l, lidar_alarm_l to indicates if there is any obstacles on the left or on the right. /lidar_alarm is a combination of both. It will try to move the robot back a little bit to release the alarm. When alarm present, no other velocity command can be executed.

rosrun simple_mobile_robot lidar_estop

Parameters can be change in parameters.yaml

# lidar brake
MIN_SAFE_DISTANCE: 0.65 # Safety distance counting from the middle of the laser scan, in m
ROBOT_WIDTH: 0.5        # Width of the robot, in m

Demo Video: https://youtu.be/-PnMeZPLats

Delay launcher

Wait for a certain time and run commands. Usually used for waiting for gazebo or rviz to finish loading.

rosrun simple_mobile_robot delay_launcher.py [sleep time] ...[commands]

[sleep time] is the amount of time to wait before running the commands, in second.

...[commands] a list of commands to run, just type as you normally do in the terminal.

Example: rosrun simple_mobile_robot delay_launcher.py 2 ls -l, this will run ls -l after 2 seconds.

Experimental

Do not use them as they are still under construction!

Trajectory Builder

A path builder that can build a sequence of via points and states between specify the start and end pose.

Absolute path move

Command the robot by specifying absolute points (with respect with odom_frame). Response to lidar_alarm to gracefully come to halt. Also listening to /append_path_queue and response to /flush_path_queue_service for adding goal points or remove all goal points.

Use Trajectory Builder to build the path.

Run:

rosrun simple_mobile_robot path_move

or rosrun simple_mobile_robot path_move test

or rosrun simple_mobile_robot path_move square 1.5

Steering Correction

A steering correction algorithm to correct the drifting caused by the passive wheel or any source. It will try to align the robot to `desired state published by path_move.

Run:

rosrun simple_mobile_robot steering_controller

If you don't want any steering correction, simply forward velocity command from the desired state published by path_move.

rosrun simple_mobile_robot des_state_forwarder

About the model

This robot model has a passive wheel to support the robot. However, it can not be simulated perfectly in Gazebo. Unlike the real world, when there is an over 90 deg rotation on that wheel, it will fight against the other wheels and cause drifting on robot's orientation.

Modified from a robot build by our lab, the original model can be found here

TODO List

  • Fix and improve path server and use path server to complete square and circle move

  • Add option of using AMCL odom instead of perfect odom from Gazebo

  • Add full navigation stack: costmap, planner, move_base, etc.