Ground surface sensing through plant foliage using an FM-CW radar

To overcome the limitations of existing height-sensing devices for depth/height control of agricultural machinery, a new technique using microwaves is being developed and tested. The advantage of this technique is its ability to penetrate a dielectric medium. A Frequency-Modulated-Continuous-Wave (FM-CW) radar system at the X-band was tested to estimate its ability to detect the ground's surface under foliage. This system configuration was developed in order to offer a low-cost, simple, non-contact measuring system for short-range measurements. For bare soil, the proposed system measured height from 0.75 to 1.5 m, with a Sampling rate of 77 Hz, it achieved accuracy of better than 5 mm on a flat, dry sand surface, and resolution of 37.5 mm. The results for ground surface sensing through plant foliage show that microwaves have the ability to penetrate through foliage and can be used as sensors for a depth/height control system. However, additional work is needed to define the optimal parameters of the microwave system and to improve the algorithm for sensing the ground surface through dense foliage.