In the obstacle detection module, redundant ultrasonic sensors
are used to increase detection resolution and sensor data
reliability. Since ultrasonic sensors have a width dihedral
detection angle, the resolution of detected obstacles is very
low. The implemented approach uses always two ultrasonic
sensors for one half of the same angle. Hence, though the
double amount of sensors is needed, the redundancy and
resolution is also doubled. Figure 3 shows the implemented
constellation using 12 ultrasonic sensors for a 360 degree
circle. For example sensor S0 and sensor S1 share one half of
their total angle.