The servo_param.yaml file contains the configuration of the pan_controller, such as the limits of the controller and step distance of each movement; also, it has screen parameters such as the maximum resolution of the camera image and offset from the center of the image. The offset is used to define an area around the actual center of the image:

    servomaxx: 0.5   #max degree servo horizontal (x) can turn 
    servomin: -0.5   # Min degree servo horizontal (x) can turn 
    screenmaxx: 640   #max screen horizontal (x)resolution 
    center_offset: 50 #offset pixels from actual center to right and 
    left 
    step_distancex: 0.01 #x servo rotation steps