rospy_turtlebot_pid

Overview

This package implements the pid controller (so far only 'p' of the pid) on the linear and angular velocity of any ground robot, such as kobuki. The linear velocity control is only in x-direction while the angular velocity control is clockwise and counter-clockwise. Waypoints are taken from the setpoint generator in "nwu" frame.

Installation

Create a catkin workspace for the project.

$ cd catkin_ws/src

Assuming that kobuki packages for respective ros-distro are installed on the firmware, git clone the dependencies in the workspace source folder 'catkin_ws/src'.

$ cd catkin_ws
$ catkin build
$ source devel/setup.bash

Dependencies

• reef_msgs
• ros_vrpn_client
• setpoint_generator
• kobuki
• kobuki_core
• kobuki_msgs
• turtlebot

Configuration

Waypoints in setpoint_generator

This step is common for hardware and simulation. These ways points are meant for turtlebot since the z-coordinate is zero. Path: setpoint_generator/waypoint_files/basic_waypoints.yaml

waypoint_list:
  [
    {position: [-1.0, -3.0, 0.0], yaw_degrees: 0},
    {position: [1.0, -3.0, 0.0], yaw_degrees: 0},
    {position: [1.0, 3.0, 0.0], yaw_degrees: 0},
    {position: [-1.0, 3.0, 0.0], yaw_degrees: 0},
    {position: [-1.0, -3.0, 0.0], yaw_degrees: 0},
    {position: [0.0, 0.0, 0.0], yaw_degrees: 0}
  ]

Coordinate Frame in setpoint_generator

• Set the following parameter manually in setpoint_generator/params/basic_param.yaml.

For turtlebot

robot_command_orientation: NWU

For copter

robot_command_orientation: NED

Hardware

• Set the following parameters manually in rospy_turtlebot_pid/config/params.yaml.

sim: false
mocap: true
safety_distance: 0.6

• Set the following parameters manually in setpoint_generator/params/basic_param.yaml.

is_sim: false
use_mocap: true

• Turn on the mocap system and create a rigid body by the name "tb3_1".
• ssh into the computer on the turtlebot.

$ roslaunch rospy_turtlebot_pid firmware.launch

Simulation

• Set the following parameters manually in rospy_turtlebot_pid/config/params.yaml.

sim: true
mocap: false
safety_distance: 0.2

Terminal window 1

$ roscore

Terminal window 2

$ roslaunch gazebo_ros empty_world.launch

Terminal window 3

$ roslaunch rospy_turtlebot_pid sim.launch

Troubleshooting

1. Turtlebot doesn't move, but I'm giving the command velocity.

Check the mapping in the firmware.launch. It should be to /mobile_base/commands/velocity (of rosnode mobile_base_nodelet_managers)

Credits

Autonomous Vehicles lab

Changelog