Ultrasonic sonar system for target localization with one emitter and for receivers

This paper presents an ultrasonic active sonar system in air constituting one emitter and four receivers. Target localization is achieved by means of intersection of four ellipsoids defined by the time of flight between emission and reception of the signal reflected by the target. This paper shows a proof of concept of the localization principle through some localization tasks conducted in a laboratory environment. The position of a spherical target is determined with an error between 1cm and 7cm depending on receiver configuration and target position. The purpose of the fully developed sonar system is to assist drones and robots in their autonomous navigation

Bio-inspired sound localization sensor with high directional sensitivity

MEMS microphones inspired by Ormia ochracea are constrained by their reliance on the resonant behavior of the system, forcing designers to compromise the goal of high amplification of directional cues to operate across the audio range. Here we present an alternative approach, namely a system optimized for the maximum amplification of directional cues across a narrow bandwidth operating purely as a sound-localization sensor for wide-band noise. Directional sensitivity is enhanced by increasing the coupling strength beyond the 'dual optimization' point, which represents the collocation of a local maximum in directional sensitivity and a local minimum in non-linearity, compensating for the loss of the desirable linearity of the system by restricting the angular range of operation. Intensity gain achieved is 16.3 dB at 10° sound source azimuth with a linear directional sensitivity of 1.6 dB per degree, while linear directional sensitivity in phase difference gain shows a seven fold increase over the 'dual optimization' point of 8 degrees phase difference per degree change in azimuthal angle

3D printed small-scale acoustic metamaterials based on Helmholtz resonators with tuned overtones

Acoustic metamaterials have been extensively studied in recent decades due to their ability to control acoustic waves. In this paper, we present a prototype of a small-scale acoustic metamaterial based on Helmholtz resonators fabricated with additive manufacturing technology. The results confirm that 3D printed small-scale metamaterials can break the mass law by creating band gaps where the sound is deeply attenuated. We have also introduced a modification of the resonators whereby overtones are exploited and tuned in order to broaden the band gap. The output of this research could be used to provide passive filtering for transducers, to improve noise cancelling headphones, as well as in other smart acoustic sensors and IoT audio applications

Bio-inspired frequency agile acoustic system

Natural passive mechanical systems such as ear tympanic membranes may show active responses by incorporating feedback mechanisms which then affect their mechanical structure. In this paper, the moth’s auditory system is used as a biological model of inspiration. A smart acoustic system which alters its natural resonance frequency was developed. Experimental results, given by a proposed-built real-time embedded system, show time and amplitude dependency towards dynamic frequency adaptation according to the intensity of acoustic input signals

End-of-Life decision tool with emphasis on remanufacturing

Remanufacturing is a product recovery strategy resulting in end-of-life products being returned to as new condition or better and receiving a warranty at least equivalent to the original. To differentiate remanufacturing from other forms of product recovery, a clear definition of a remanufactured product is essential. At present two distinct methods for understanding end-of-life recovery strategies exist; a) the use of tools and b) definitions. These current methods fall short however of categorically stating what is and what is not a remanufactured product. Therefore, the responsibility of classifying a product as remanufactured is left to individuals and organizations and so potential exists for products to be incorrectly labelled. By firstly examining the problems associated with using existing methods to determine the status of end-of-life product, and why product identification is important, this paper then goes on to present a new simple innovative method to quickly and accurately determine the status of a product which has undergone an end-of-life recovery strategy, by virtue of a bespoke tool. The tool presented is the result of two rounds of academic and industrial feedback; an initial tool was presented, and underwent critique, at the International Conference on Remanufacturing 2015 with an updated tool then subject to another independent review from academic and industrial stakeholders. The main benefits associated with this tool are, a) a quick way to identify the status of a product, b) a method for researchers to quickly determine the best terminology for end-of-life products which have received a recovery treatment, c) a quick and reliable method to check whether a remanufactured product is labelled as something else, d) an additional way to ensure compliance with existing legislation and standards, and e) an identification of only the essential characteristics of a remanufactured product

Towards the development of a frequency agile MEMS acoustic sensor system

Designing acoustic sensors with adaptable frequency responses is of great interest in order to deal with diverse application requirements. A bio-inspired acoustic concept exploiting frequency agility using a MEMS microphone front-end is presented. Simulations and experimental results show adaptations of the microphone’s acoustic frequency response according to applied DC voltage potentials. Finally, the microphone is demonstrated as part of an integrated adaptive frequency sensor feedback loop. Such acoustic sensor systems can be used in many applications requiring high frequency discrimination and agile tuning

Active hearing mechanisms inspire adaptive amplification in an acoustic sensor system

Over many millions of years of evolution, nature has developed some of the most adaptable sensors and sensory systems possible, capable of sensing, conditioning and processing signals in a very power- and size-effective manner. By looking into biological sensors and systems as a source of inspiration, this paper presents the study of a bio-inspired concept of signal processing at the sensor level. By exploiting a feedback control mechanism between a front-end acoustic receiver and back-end neuronal based computation, a nonlinear amplification with hysteretic behavior is created. Moreover, the transient response of the front-end acoustic receiver can also be controlled and enhanced. A theoretical model is proposed and the concept is prototyped experimentally through an embedded system setup that can provide dynamic adaptations of a sensory system comprising a MEMS microphone placed in a closed-loop feedback system. It faithfully mimics the mosquito’s active hearing response as a function of the input sound intensity. This is an adaptive acoustic sensor system concept that can be exploit by sensor and system designers within acoustics and ultrasonic engineering fields

Bio-inspired active amplification in a MEMS microphone using feedback computation

Auditory signal processing relies on feedback mechanisms between mechanical and electrical systems that work together to enhance acoustic conditioning. In this paper a nonlinear amplification mechanism in the mosquito's auditory system is exploited as a model of inspiration. An acoustic system that provides active amplification of sound was developed using feedback computation integrated with a MEMS microphone to implement the concept. Experimental results generated by a purpose-built embedded system show signal amplification and hysteresis which replicate the response shown by the biological mosquito’s hearing system as a function of input sound intensity

Generating characteristic acoustic impedances with hydrogel based phononic crystals for use in ultrasonic transducer matching layers

The impedance matching layer has a critical effect on ultrasonic transducer performance, but it is difficult to source materials that have the appropriate acoustical properties. A method that utilises effective property relations of composites and finite element analysis is used to design a hydrogel-steel based phononic crystal, quarter wavelength impedance matching layer that can match bespoke configurations. Phononic crystal band structures are calculated to determine an appropriate lattice scale length, and frequency domain studies are carried out to compare this novel type of matching layer with an ideal bulk layer. Transmitted pressure curves are as expected and suggest that this design type will be suited for fabrication and testing

Towards a 3D printed acoustic sensor inspired by hair-like structures of insects : a study of hair shape and size

Over ages insects evolved to be smaller and more efficient with several miniature sensing mechanisms reacting to the environment around them. The hair-like structures, called trichobothria or trichoid sensilla, are fascinating mechanisms that allow insects to react to airflow and low frequency, near field, sound. Nevertheless, it is thought that from this sensing structure, other sensing mechanisms are derived by a change on the hair structure. This includes sensing of odours, acceleration, touch, temperature, as well as a gyroscope-like mechanism. This project proposes the use of advanced 3D printing techniques to create a sensor inspired by the trichoid sensilla of insects. Inspiration comes, in particular, from the sensilla structure of the caterpillar Barathra brassicae, and one from the crickets previously studied in the EU CILIA project. The focus is on developing a mechanical structure that responds to sound. Arrays of sensors that react at different sound frequencies allow frequency content measurement of a sound without the need for computationally expensive digital processing techniques (DSP)