Turtlebot 3 Scheduling platform

Prerequisite

$ sudo apt install ros-$ROS_DISTRO-turtlebot3-gazebo

Installation

$ mkdir -p ~/catkin_ws/src
$ cd ~/catkin_ws/src
$ git clone git@github.com:duynamrcv/turtlebot3_scheduling.git
$ cd ..
$ catkin build

Demo

For single robot

Launch Turtlebot3 robot

$ roslaunch turtlebot3_scheduling single.launch

Assign next target

$ rosservice call /next_goal "goal:
  position:
    x: 1.0
    y: 0.0
    z: 0.0
  orientation:
    x: 0.0
    y: 0.0
    z: 0.0
    w: 1.0" 

For multiple robots

To be defined

Explanation

State Diagrams

stateDiagram
    [*] --> IDLE
    IDLE --> [*]
    IDLE --> ASSIGNED
    ASSIGNED --> IDLE

• IDLE state to be ready to receive the task of moving to the next target.
• ASSIGNED state to make a move to the next target without being affected by further assignment.

Moving to pose

Given the robot position $p=\left[x, y, \theta\right]^T$ and the goal position $p_g=\left[x_g, y_g, \theta_g\right]^T$

Firstly, the different position is given as follows:

$$x_d=x_g-x$$ $$y_d=y_g-y$$

Convert to the polar coordination

$$\rho = \sqrt{x_d^2+y_d^2}$$ $$\alpha = \tan^{-1}\dfrac{y_d}{x_d} - \theta$$ $$\beta = \theta_d - \theta - \alpha$$

The control signal therefore can be computed as follows:

$$v = k_\rho\rho$$ $$w = k_\alpha\alpha + k_\beta\beta$$

Ensure the steering capacity: $\alpha > \pi /2$ or $\alpha < -\pi/2$, revert the velocity direction $v = -v$