A low-cost, composite sensor array combining ultrasonic and infrared proximity sensors

In this paper we describe our approach to the design of proximity sensor arrays. Each sensing element of the proximity sensor array is a composite sensor, i.e. a sensor which is composed of an in-air ultrasonic rangefinder and an infrared detector. This sensor arrangement is capable, in principle, to achieve a perception of the explored objects that is not necessarily limited to their geometrical properties (size, shape and location relative to the sensor); possibly, the perception can be extended to other relevant features. In this paper, we show that, in principle, a sort of perception of the surface reflectance (the color) is achievable. The concept of the proposed sensor array spans a wide range of potential applications in flexible industrial automation, service robotics and autonomous mobility. The system described, in particular, is intended for providing an advanced wheelchair with the navigational capabilities required for improving the driving skills of disabled users.