ROS supports sonar and infrared sensors with the sensor_msgs/Range Message. Using it is pretty straightforward, but there are two values that I have spend quite some time on tuning: field_of_view and max_range.

1. max_range:

The SRF05 has a maximum range of about four meter. But that is not what I have set as max_range value because of the high field of view of this sensor (see below) with a maximum of about 55°. That means in an area of four meter and 55° a table leg is enough to mark the full area as occupied. To avoid this situation I set the max range value to only 0.5 meter.

2. field_of_view:

The field of view is not constant. For the details hobbizine has a good article which I highly recommend to read, quote:

"The beam width (or beam angle) of ultrasonic range finders is typically described as being a cone of a certain angle (...) The conclusion of this logic would be that the detection zone extends from the sensor in an even, steadily expanding arc until it reaches the 4 meter limit of the SRF05 range. In reality the detection zone expands at about 55° for the first meter and then the rate of expansion starts to decay. At about 2 meters distance from the sensor the angle of the detection zone is closer to 40° with the zone reaching a maximum width of about 80-100 centimeters. From this point the detection zone will begin to narrow, ultimately reaching zero when the distance from the sensor is a little more than 4 meters."

I currently use 30° for the 0.5m max range