Fix: Correct motor control logic in cmdVelCallback function

[anurag-choudhury]

PR Summary

This PR resolves multiple issues and introduces new functionalities related to motion control and odometry for the robot using the Roboteq FBL2360TE motor controller.

---

Problem Resolved

1. cmdVelCallback Improvements:

• Fixed an issue where the second motor was not being controlled correctly, causing improper robot motion.
• Previous logic for combining linear and angular velocities to compute motor speeds had errors, leading to inaccurate motor behavior.

2. Opposite Direction Rotation in Diff-Drive:

• Resolved an issue causing the robot to rotate in the opposite direction when turning.
• Fixed kinematic calculations to ensure proper left and right motor behavior.

---

New Features

1. Odometry Calculation Node:

• Added a new node to calculate odometry (odom_calculation_node) based on encoder data.
• Computes the robot's position (x, y) and orientation (theta) in the odom frame.
• Publishes odometry information and broadcasts the transform (odom -> base_link).

2. Launch File Modifications:

• Updated the launch file to include the new odometry calculation node for seamless integration.
• Suggested renaming the launch/driver.py file to launch/driver.launch.py for better ROS 2 launch compatibility.

---

Impact

1. Enhanced Motion Control:

• Both motors now respond appropriately to combined linear and angular velocity commands.
• Fixed behavior ensures accurate forward motion, turning, and stopping commands.

2. Accurate Odometry:

• Provides precise position and orientation updates for navigation and mapping applications.

3. Improved Debugging:

• Logs added to both cmdVelCallback and the odometry calculation node for better visibility of internal states and computations.

---

Testing

Hardware Validation:

• Forward Motion: Verified that linear.x > 0 moves both motors at equal speeds.
• Turning: Confirmed angular.z ≠ 0 generates differential motor speeds for turning.
• Stopping: Validated that linear.x = 0 and angular.z = 0 halts both motors.

Odometry Node Validation:

• Verified odometry outputs using encoders for position (x, y) and orientation (theta).
• Confirmed that transform broadcasting (odom -> base_link) aligns with real-world robot motion.

Modes Tested:

• Tested in open-loop (power control) and closed-loop (RPM control) modes.

---

Checklist

• Fixed second motor control in cmdVelCallback.
• Resolved opposite rotation in diff-drive.
• Odometry node #4 Added odometry calculation node.
• Updated launch file to integrate new node.
• Logs added for better debugging.
• Documentation and comments updated for clarity.

---

Additional Notes

• Suggestion: Rename the file launch/driver.py to launch/driver.launch.py to improve readability and ROS 2 launch compatibility.
• Ready for review and feedback. Additional improvements or suggestions are welcome!