Voice commands operated on a Turtlebot2i 🤖

◦ Developed with the following software and tools:

This documentation provides an overview of a Python script for controlling a robot using voice commands with updated grammar for a specific syntax of commands through ROS (Robot Operating System). The script utilizes the speech_recognition library to recognize voice inputs and ROS for robot control.

Prerequisites

Before running the script, make sure you have the following installed:

• ROS (Robot Operating System)
• speech_recognition Python library
• Appropriate ROS packages (e.g., std_msgs, geometry_msgs)

Bot used:

• Turtlebot2i

Script Overview

The Python script (voice_control.py) listens to voice commands from a microphone and translates them into robot motion commands. Here's a breakdown of the script:

Importing Dependencies

import rospy
from std_msgs.msg import String
import speech_recognition as sr
from geometry_msgs.msg import Twist

• The script starts by importing necessary libraries and ROS message types.

Initializing some Global Variables

motion_command = Twist()
motion_publisher = None  # Initialize the motion_publisher
text_publisher = None  # Initialize the text_publisher

• motion_command: Stores the robot's motion commands.
• motion_publisher: Initializes the motion command publisher.
• text_publisher: Initializes the text publisher.

speech_to_text_callback Function

def speech_to_text_callback(event):
    global text_publisher  # Declare text_publisher as global

    r = sr.Recognizer()

    try:
        with sr.Microphone() as source:
            audio = r.listen(source)
            text = r.recognize_google(audio)
            rospy.loginfo("Recognized text: %s", text)
            text_publisher.publish(text)  # Publish the recognized text

    except sr.UnknownValueError:
        rospy.logwarn("Could not recognize speech")

    except sr.RequestError as e:
        rospy.logerr("Speech recognition error: %s", e)

• speech_to_text_callback listens to voice input from the microphone and uses the speech_recognition library to recognize the speech.
• Recognized text is published to the ROS topic /recognized_text.

process_voice_command Function

def process_voice_command(text):
    global motion_command, motion_publisher

    if "left" in text:
        # Handle left turn command
        # ...

    elif "right" in text:
        # Handle right turn command
        # ...

    elif "straight" in text:
        # Handle moving straight command
        # ...

    else:
        # Handle unrecognized command
        # ...

• process_voice_command processes the recognized text and generates appropriate motion commands based on the recognized voice commands.

stop_robot Function

def stop_robot():
    global motion_command, motion_publisher
    # Stop the robot by setting linear and angular velocities to zero
    motion_command.linear.x = 0.0
    motion_command.angular.z = 0.0
    motion_publisher.publish(motion_command)  # Publish the stop command

• stop_robot is used to stop the robot by setting its linear and angular velocities to zero.

Main Script

if __name__ == '__main__':
    rospy.init_node('voice_commands', anonymous=True)
    text_publisher = rospy.Publisher('/recognized_text', String, queue_size=10)  # Publish recognized text
    # ...

Grammar included to make commands follow a particular syntax:

text_grammar = """
    # Command format: "Move <direction> by <distance> units"
    # e.g., "Move left by ten units", "Move right by five units", "Turn left", "Turn right", "Stop", "Move straight"
    direction = "left" | "right" | "straight"
    distance = /([1-9]|10|1[1-9]|20|30)/  # Matches numbers from 1 to 30
    units = "units"
    command = ("move" direction "by" distance units | "turn" direction | "stop" | "move" direction )
	"""

• The main script has the grammar, initializes the ROS node, sets up publishers and subscribers, and starts the ROS spin loop.

Usage

1. Ensure that ROS is properly set up on your system.

2. Install the required Python libraries, including speech_recognition.

3. Run the script using rosrun.

4. The script will listen to your voice commands and control the robot accordingly.

Note

• Customize the motion commands within the process_voice_command function to match your robot's control interface.

• Adjust the timers and sleep durations as needed for your application.

• Ensure that the appropriate ROS topics (/recognized_text and /cmd_vel) are available and match the topics used in the script.

That's it! You now have a voice-controlled robot using ROS and Python.

Customization

You can customize this code by modifying the text_grammar to recognize specific voice commands and adjusting the robot's motion commands based on your requirements. Additionally, you can extend the code to handle more complex voice commands and add error handling as needed.

Please note that you should customize the handling of specific voice commands within the process_voice_command function to match the behaviour of your robot. Additionally, make sure that the ROS topics used in the script (/recognized_text and /cmd_vel) are correctly configured for your robot's setup.