ABSTRACT
Methods for autonomous navigation systems using sonars in air traditionally use the time-of-flight technique for obstacle detection and environment mapping. However, this technique suffers from constructive and destructive interference of ultrasonic reflections from multiple obstacles in the environment, requiring several acquisitions for proper mapping. This paper presents a novel approach for obstacle detection and localisation using inverse problems and compressed sensing concepts. Experiments were conducted with multiple obstacles present in a controlled environment using a hardware platform with four transducers, which was specially designed for sending, receiving and acquiring raw ultrasonic signals. A comparison between the performance of compressed sensing using Orthogonal Matching Pursuit and two traditional image reconstruction methods was conducted. The reconstructed 2D images representing the cross-section of the sensed environment were quantitatively assessed, showing promising results for robotic mapping tasks using compressed sensing.
ABSTRACT
This work presents a new perspective for fluorescence signal detection using specific optics on Lab-on-Chip devices. An apparatus was designed and implemented in order to assess the performance of a fluorescence technique using different detection spot configurations, using the chip itself as a waveguide for illumination. The experiments conducted investigate the influence of the dimensions - diameter and height - of the spot on the amplitude of the detection output signal. Results show that the configuration of optical interfaces must be considered in order to improve detection output, or to be able to detect less fluorophore molecules in the spot.
