A mobile robot navigating with a polarization compass

Fig. 4:

The POL-sensors of Sahabot 1 as seen from above. The six sensors are arranged in pairs, each of which is connected to a log ratio amplifier forming a polarization-opponent unit (POL-OP unit; compare Fig. 3). Each POL-OP unit is tuned to a different e-vector orientation, i.e. parallel, 60° and 120° to the robots' long axis.