ABSTRACT: Ultraschallsensoren werden bei mobilen Robotern vorwiegend zur Kollisionsvermeidung eingesetzt. Ihre Verwendbarkeit zur Navigation
(Positionsbestimmung des Roboters) wird seit Jahren untersucht, wobei diese Arbeiten praktisch ausschließlich einen zweidimensionalen
Ansatz verwenden. In den hier beschriebenen Untersuchungen wird die Modellierung von Objektkanten in einem allgemeinen, dreidimensionalen
Ansatz durchgeführt. Mit einer Karte dieser gewonnenen Modelldaten aus einer Lernphase und den laufenden Messungen in der
Anwendungsphase lässt sich hierauf die Position des Roboters bestimmen. Hauptschwierigkeiten der Anwendung liegen im statistischen
und entfernungsabhängigen Verhalten der Ultraschallsignale im Randbereich der Schallkeule des Wandlers sowie in der Messgenauigkeit
der Entfernungsmessung. In diesem Beitrag werden auch Möglichkeiten aufgezeigt, durch eine verbesserte Signalverarbeitung
der vom Wandler empfangenen Signale die erreichte Messgenauigkeit in der Entfernungsmessung für die Ortung zu erhöhen.
In the field of mobile robotics, ultrasonic sensors are mainly used for collision avoidance. Their usability for robot navigation
and position detection has been investigated for years but restricted solely to 2D methods. The research presented in this
paper has the goal to model object edges more generally in three dimensions. A map of modeled object edges, gathered from
a learning phase, in combination with the actual measured data allows the determination of the robot position. The main difficulties
in applying this method are the statistical and distance dependent behavior of the signals near the boundary of the sound
lobe and the accuracy of distance measurement values. Additionally, possibilities to increase the accuracy in the distance
measurements with advanced signal processing of received signals are shown in this work.
e & i Elektrotechnik und Informationstechnik 04/2012; 121(2):58-63.
ABSTRACT: One major problem of ultrasonic distance measurement is the strongly object dependent detection range: objects providing strong echoes (e.g. well aligned planes) can be detected in a much wider distance than "small objects" reflecting only a fractional amount of the incoming sound energy (e.g. edges). In conventional sensor constructions not only the maximum measurable distance along the sensor axis varies, but also the field of detection where measurement values are delivered. As a consequence, the decision if an object is located inside or outside a defined area is hardly possible without a priori knowledge of the object's reflection properties. This work presents a measurement principle that provides a well defined and object independent detection area that moreover can be dynamically adjusted to achieve high resolution for algorithms based on contact-less ultrasonic "touching" of objects.
Sensors, 2004. Proceedings of IEEE; 11/2004
ABSTRACT: The pulse compression method adds several improvements to ultrasonic distance measurement systems. Especially in conjunction with the one bit correlation method, which eliminates the amplitude influence and offers real time possibilities several advanced applications become possible. After a survey of several measurement variants the influence of the orientation of a piston modeled transducer is examined to realize two most attractive cases. At last some measurements on real transducers are presented to verify the supposed model of the piston membrane.
Sensors, 2003. Proceedings of IEEE; 11/2003
ABSTRACT: This paper gives a survey of problems of ultrasonic distance measurement systems with regard to applicability in industrial environment as well as for presence detection and also for high resolution measurement tasks. The impulse compression method is able to handle the mentioned problems. To simplify the real time signals processing a one bit correlation technique is introduced. Next, the comparison between A-B-measurement and use of passive reflection leads to a new method of active reflection in ultrasonic systems which combines the advantages of both methods. The active and passive reflection is compared and their common and different aspects are shown. In the following the radiation pattern of an ultrasonic transducer is analyzed and its influence on broadband signal emission and reception in conjunction with correlation based receivers is discussed. A prototype of an active reflection system is presented and its final configuration is shown.
Instrumentation and Measurement Technology Conference, 2002. IMTC/2002. Proceedings of the 19th IEEE; 02/2002