Jackal ROS Control Script

Overview

This Python script provides a basic obstacle avoidance and safety control mechanism for a Jackal robot in a ROS (Robot Operating System) environment. The script subscribes to laser scan data, monitors the surroundings, and adjusts the robot's velocity commands to avoid collisions.

Requirements

• ROS (Robot Operating System)
• Python 2.7 or later
• NumPy
• Jackal simulation
• Tested on ubuntu 18.04 with ROS Melodic

For more information on the jackal and how to connect to it, refer to the doc/jackal.pptx and the user manuals

Installation

1. Ensure that ROS is installed on your system.
2. Create or go to your ros workspace.
3. Clone this repository into your ROS workspace.

   git clone https://github.com/SherbyRobotics/jackal.git

4. Build your ROS workspace.

   cd your-ros-workspace
   catkin_make

Usage

1. Run the control script:

   roslaunch basic_pkg start_basic.launch 

2. Launch the Gazebo simulator for Jackal with the following command:

   roslaunch jackal_gazebo jackal_world.launch config:=front_laser

Node Details

• Node Name: control_test

• Subscribed Topics:

  • /scan: Laser scan data from the robot's sensors.
  • /front/scan: Laser scan data specifically for the front portion of the robot.
  • /twist_marker_server/cmd_vel: Velocity commands from the twist marker server.
  • /bluetooth_teleop/cmd_vel: Velocity commands from Bluetooth teleoperation.
  • /joy_teleop/cmd_vel: Velocity commands from joystick teleoperation.
  • /jackal_velocity_controller/odom: Odometry data for monitoring the Jackal's speed.

• Published Topics:

  • /con_vel: Twist data to move the jackal.

The con_vel topic is sent to a twist_mux node to control the jackal. The priority of con_vel can be changed in /config/twist_mux.yaml .

Parameters

• front_scan_point: Number of points used for the front laser scanner.

Behavior

The script continuously monitors the laser scan data to detect obstacles in front of the Jackal. If an obstacle is too close (safe_distance), it triggers a safety mode, reducing or stopping the robot's linear velocity. The control script can be adjusted for specific applications by modifying the parameters and tuning the reaction time, decceleration, and other control parameters.

Feel free to customize and extend this script based on your specific requirements.