In August 1990, tests were performed to investigate the usefulness of a horizontally scanning Doppler acoustic technique in shallow water. Comparisons of radial velocity estimates from a vertical fan beam versus a horizontally aimed pencil beam indicate no degradation attributable to multiple reflections from the surface and bottom. Further tests, in which ping-to-ping phase-coherent means are ...

Sonar, laser and stereo are common sensors used for safeguarding, mapping and navigation in robotic applications. However, vacuum, dust, fog, rain, snow and light conditions found in construction, mining, agricultural and planetary-exploration environments compromise the effectiveness of these sensors. Sonar can not operate in vacuum conditions, low visibility and scanning mechanisms limit lase...

This paper develops expressions which relate the parameters of a sonar to the processing power and memory required for the system. These expressions can be used when designing a sonar t o ensure that realistic demands are placed on the processing engine. Benchmark test results are also presented for simulation algorithms running on a variety of machines. RESUME Ce document ddveloppe des express...

In this paper, we describe the use of a broadband, frequencymodulated sonar sensor (a CTFM sonar) for generating maps of structured environments for robots and autonomous systems. The major advantage of using these sensors is that the information generated is reliable enough to extract the geometry and type of certain features with very few measurements; hence, maps can be generated rapidly. Al...

This paper presents a method for relocation of a mobile robot using sonar data. The process of determining the pose of a mobile robot with respect to a global reference frame in situations where no a priori estimate of the robot's location is available is cast as a problem of searching for correspondences between measurements and an a priori map of the environment. A physically-based sonar sens...

A mechanicaly scanned imaging sonar, MSIS, produces a 2D image of the range and bearing of return intensities. The pattern produced in this image depends on the enviormental feature that caused it. These features are very useful for underwater navigation but the inverse mapping of sonar image pattern to environmental feature can be ambiguous. We investigate problems associated with using MSIS f...

In this work, a simple, low-cost and reliable electronic module for coupling of an ultrasonic range-finder with a mobile robot’s microprocessor system is presented. A software filter for correct reading of the ultrasonic data is presented as well. Due to the software filter, a shielding of robot and sonar’s electronic modules is not required. In this way compactness and low price of the device ...

Dolphins and porpoises have excellent biosonar ability, which they use for navigation, ranging and foraging. However, the role of biosonar in free-ranging small cetaceans has not been fully investigated. The biosonar behaviour and body movements of 15 free-ranging finless porpoises (Neophocaena phocaenoides) were observed using electronic tags attached to the animals. The porpoises often rotate...

Bottlenose dolphin (Tursiops truncatus) echolocation resolution greatly exceeds measured beampattern and conventional hearing model performance. We explore the idea that teeth might aid conventional hearing. Nerve conduction requires neural delay lines, a requisite that might be met by unexplained specialised cell arrangements already reported. Jawbone resonance displays selectivity at 25-35 de...

Recordings of narwhal (Monodon monoceros) echolocation signals were made using a linear 16 hydrophone array in the pack ice of Baffin Bay, West Greenland in 2013 at eleven sites. An average -3 dB beam width of 5.0° makes the narwhal click the most directional biosonar signal reported for any species to date. The beam shows a dorsal-ventral asymmetry with a narrower beam above the beam axis. Thi...