Modifying dwb controller

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Hello,

Current behavior: If the robot if facing away from the goal/ next waypoint, the path is planned which includes linear and angular motion.

Expected behavior: If the robot is facing away from the goal/ next waypoint, reduce the angle between robot orientation and angle to goal (while setting linear speed to 0) & once the angle is reduced, retrieving the previously set value for linear velocity.

I would like to know how to modify the dwb source code to achieve this? (How does it score trajectory/ how to control the trajectory rollout parameters)

I appreciate the community's help in advance.

Thank you & Cheers!!