Navigation control for exploration rover with Microwave Doppler sensors

Microwave Doppler sensors commonly used in automatic-door systems have been used in a rover navigation system. A collimated microwave beam with an angular width of ±3° at a frequency of 24 GHz was emitted from a sensor (A) on a dish antenna 30 cm in diameter. Another sensor (B), which works as a detector, was installed on the rover. The rover was programmed to make a right turn when the microwave signal was above a specified level and to make a left turn when the signal was than that level. The rover started from a point 70 m away and approached to within 1.5 m of sensor A in 4-5 min. This navigation method is useful when GPS is not usable.