Environmental Exploration Based On A Three-dimensional Imaging Radar Sensor

Abstract

Well-known sensors applied for remote sensing tasks in the field of autonomous mobile robots are active range discriminating optical and acoustical devices (e.g. laser range cameras, ultrasonic sensors) and passive sensors like CCD-cameras. Regarding the frequency domain they use, we see that, excluding the acoustic devices, they cover the range from about 400 nm to 1500 nm (visual and infrared region). In this paper we present an alternative multitask radar imaging sensor with high spatial resolution operating at a wavelength of 3 mm, corresponding to a frequency of 94 GHz, especially designed for sensing 3-D geometrical properties of an autonomous vehicle environment in indoor situations. The main features of this imaging radar sensor approach are a broad field of vision, direct access to range and velocity information via Doppler signal processing. This is achieved by implementing a coherent pulse doppler radar principle. A short introduction of the system design and technical parameters is given first. Then we concentrate on the sensors various operating modes (e.g. scanning, tracking, 3-D imaging, map generation) proved by presentation of several radar images and different kind of maps we obtained in laboratory surroundings as well as fabrication plants. On the basis of the radar maps an impression of typical millimeter-wave scattering phenomena is given. Finally we discuss the quality of the preprocessed radar data and the contribution of this microwave imaging device within a multisensor environment which is built up in the joint research project SFB 331 at our university.