ORCID Profile
0000-0002-1988-2328
Current Organisation
Central Queensland University
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Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 08-2019
Publisher: IEEE
Date: 04-2014
Publisher: IEEE
Date: 12-2013
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 06-2023
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 09-2017
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 04-2023
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 15-02-2022
Publisher: MDPI AG
Date: 18-03-2019
DOI: 10.3390/S19061350
Abstract: Gait analysis in unrestrained environments can be done with a single wearable ultrasonic sensor node on the lower limb and four fixed anchor nodes. The accuracy demanded by such systems is very high. Chirp signals can provide better ranging and localization performance in ultrasonic systems. However, we cannot neglect the multi-path effect in typical indoor environments for ultrasonic signals. The multi-path components closer to the line of sight component cannot be identified during correlation reception which leads to errors in the estimated range and which in turn affects the localization and tracking performance. We propose a novel method to reduce the multi-path effect in ultrasonic sensor networks in typical indoor environments. A gait analysis system with one mobile node attached to the lower limb was designed to test the performance of the proposed system during an indoor treadmill walking experiment. An optical motion capture system was used as a benchmark for the experiments. The proposed method gave better tracking accuracy compared to conventional coherent receivers. The static measurements gave 2.45 mm standard deviation compared to 10.45 mm using the classical approach. The RMSE between the ultrasonic gait analysis system and the reference system improved from 28.70 mm to 22.28 mm. The gait analysis system gave good performance for extraction of spatial and temporal parameters.
Publisher: MDPI AG
Date: 27-04-2017
DOI: 10.3390/S17050976
Publisher: Acoustical Society of America (ASA)
Date: 03-2019
DOI: 10.1121/1.5101390
Abstract: Many bat species, such as horseshoe bats, move their external auditory periphery (noseleaf and pinnae) during emission/reception of their biosonar signals. This peripheral dynamics has already been shown to enhance sensory information encoding at the level of the analog echo waveforms. However, the bats' brains do not process any analog waveforms directly but rely on spike codes generated in the auditory nerve instead. Hence, it is desirable to evaluate the effect of the peripheral dynamics at the level of these spike codes. As input for this analysis, natural foliage echoes akin to the forest environments experienced by bats were recorded using a biomimetic robot with a dynamic periphery similar to that of horseshoe bats. The echoes were converted into neural spike trains through a signal-processing model of the bats' cochlea/auditory nerve. The effect of the dynamic periphery was then investigated using information-theoretic techniques. As a first step, entropy was estimated to quantify coding capacity. The results showed an increased entropy within signals corresponding to a dynamic periphery when compared to a static periphery. For the next steps, the variability in characteristic spike train features such as spike timing, spike rates, and spike intervals will be characterized with additional information-theoretic methods.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 09-2023
Publisher: Institution of Engineering and Technology (IET)
Date: 2019
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 06-2021
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 15-01-2017
Publisher: Acoustical Society of America (ASA)
Date: 03-2019
DOI: 10.1121/1.5101388
Abstract: Current models of the initial stages of auditory processing in mammals usually agree that the input signals are split into a bank of bandpass filters. However, the available models differ substantially in their level of complexity and the number of parameters needed. In the current work, the varying levels of complexity in filterbank models of the basilar membrane have been evaluated in the context of modeling the cochlear processing of natural biosonar echoes in horseshoe bats. To this end, three different types of filterbank models have been implemented to represent the range of complexity spanned by models that are in use for the human inner ear: The simplest model, a gammatone filterbank, is a linear model with symmetric filter transfer functions. The gammachirp filterbank is also linear, but mimics the asymmetric transfer functions of the basilar membrane. Finally, the dual resonance nonlinear (DRNL) model adds a level-dependent behavior. Here, all three models have been adapted to the specifics of the basilar membrane of horseshoe bats which is characterized by an “auditory fovea” with exceptionally high filter qualities. The outputs of the different models have been encoded into a sequence of neural spike times before being evaluated with various information-theoretic methods.
Publisher: Acoustical Society of America (ASA)
Date: 09-2018
DOI: 10.1121/1.5067841
Abstract: Bats and toothed whales (odontocetes) have both independently evolved sophisticated biosonar systems. This raises the question how similar the functional principles of these systems are. Could, for ex le, insights gained from bats be assumed to hold for odontocetes or vice versa? Could both systems be lumped together as a single source of inspiration for novel engineering approaches to sonar sensing? Similarities and differences between the biosonar systems of bats and odontocetes are likely to depend on the respective acoustic environments in which these systems have evolved as well as on the evolutionary starting points and capabilities for adaptations of these two very different phylogenetic groups. In this presentation, the focus will be on comparing the acoustic environments of bats and odontocetes. The acoustics of biosonar sensing can be organized into three different aspects: (i) the properties of the propagation medium, (ii) the geometry and material of the boundaries that limit the propagation channel (this includes targets of interest and clutter), and (iii) the time-frequency and spatial properties of the sources. In this presentation, these aspects will be reviewed for the in-air biosonar of bats. In the companion talk, the same will be done for the underwater biosonar of the odontocetes.
Publisher: Acoustical Society of America (ASA)
Date: 03-2019
DOI: 10.1121/1.5101389
Abstract: Biosonar echoes received by bats in their natural habitats are short, highly time-variant acoustic waveforms. Because of these signals properties, the way in which the bats' auditory nerve represents the echoes could be a model for how sparse neural time-code can capture salient signal features. Here, the spike-encoding of natural echoes has been studied based on a large data set containing about 220 00 echoes that were collected by hand-carrying a biomimetic robotic sonar head through forest environments. The sonar head was equipped with flexible noseleaf and pinna shapes that could deform during pulse emission/echo reception in a similar fashion to what horseshoe bats do. This peripheral dynamics was turned on for half of the recoded echoes and turned off for the other half. The echo waveforms were transformed into spike trains using two spike-generation models, each with different levels of complexity: The simplest version was a “leaky integrate-and-fire model" in the more complex version, a response kernels was added to model the refractory behavior of the neurons. The input to the spike generation models were the outputs of three different basiliar membrane models of varying complexity levels. The coding capacity of the spike trains has been evaluated using information-theoretic methods.
Publisher: Elsevier BV
Date: 05-2020
Publisher: IEEE
Date: 12-2012
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 15-11-2020
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 12-2017
Publisher: MDPI AG
Date: 27-07-2018
DOI: 10.3390/S18082447
Abstract: Ranging based on ultrasonic sensors can be used for tracking wearable mobile nodes accurately for a long duration and can be a cost-effective method for human movement analysis in rehabilitation clinics. In this paper, we present a Doppler-tolerant ultrasonic multiple access localization system to analyze gait parameters in human subjects. We employ multiple access methods using linear chirp wave-forms and narrow-band piezoelectric transducers. A Doppler shift compensation Technique is also incorporated without compromising on the tracking accuracy. The system developed was used for tracking the trajectory of both lower limbs of five healthy adults during a treadmill walk. An optical motion capture system was used as the reference to compare the performance. The average Root Mean Square Error values between the 3D coordinates estimated from the proposed system and the reference system while tracking both lower limbs during treadmill walk experiment by 5 subjects were found to be 16.75, 14.68 and 20.20 mm respectively along X, Y and Z-directions. Errors in the estimation of spatial and temporal parameters from the proposed system were also quantified. These promising results show that narrowband ultrasonic sensors can be utilized to accurately track more than one mobile node for human gait analysis.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 09-2019
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 04-2023
Publisher: Elsevier BV
Date: 12-2021
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 07-2016
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 06-2022
Publisher: Acoustical Society of America (ASA)
Date: 03-2019
DOI: 10.1121/1.5101387
Abstract: The sophisticated biosonar systems of horseshoe bats have enabled these animals to navigate and pursue prey in complex environments. A conspicuous peripheral dynamics in which the animals' noseleaves and pinnae change during biosonar behaviors could play an important role in enabling these capabilities. It may be hypothesized that for the integration between peripheral dynamics and neural signal processing/estimation to be maximally effective, the periphery should be controlled by feedback from the output of the subsequent neural echo processing. In the way, the specifics of sensory information encoding in the periphery could be controlled based on the needs of the neural signal processing. As a first step towards such an integration in a biomimetic sonar head, a computational model for the inner ear and the auditory nerve's spike code has been integrated with a dynamic periphery that—like the computational models—mimics horseshoe bats. For each model stage, alternative versions with different levels of complexity have been implemented to test how module complexity and the values of the associated parameters affect the capacity of the echo representation to encode sensory information. These effects have been tested based on a large dataset of 220 000 echoes collected in natural forest environments.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2018
Publisher: MDPI AG
Date: 04-2019
DOI: 10.3390/S19071566
Abstract: The use of renewable energy has increased dramatically over the past couple of decades. Wind farms, consisting of wind turbines, play a vital role in the generation of renewable energy. For monitoring and maintenance purposes, a wind turbine has a variety of sensors to measure the state of the turbine. Sensor measurements are transmitted to a control center, which is located away from the wind farm, for monitoring and maintenance purposes. It is therefore desirable to ensure reliable wireless communication between the wind turbines and the control center while integrating the observations from different sensors. In this paper, we propose an IoT based communication framework for the purpose of reliable communication between wind turbines and control center. The communication framework is based on repeat-accumulate coded communication to enhance reliability. A fusion algorithm is proposed to exploit the observations from multiple sensors while taking into consideration the unpredictable nature of the wireless channel. The numerical results show that the proposed scheme can closely predict the state of a wind turbine. We also show that the proposed scheme significantly outperforms traditional estimation schemes.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 10-2022
Publisher: IEEE
Date: 07-2013
Publisher: ACM
Date: 26-03-2019
Publisher: IEEE
Date: 07-2018
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 15-06-2017
Publisher: Emerald
Date: 20-05-2019
Abstract: As an automatic welding process may experience some disturbances caused by, for ex le, splashes and/or welding fumes, misalignments oor positioning, thermally induced deformations, strong arc lights and ersified welding joints/grooves, precisely identifying the welding seam has a great influence on the welding quality. This paper aims to propose a robust method for identifying this seam based on cross-modal perception. First, after a welding image obtained from a structured-light vision sensor (here laser and vision are integrated into a cross-modal perception sensor) is filtered, in a sufficiently small area, the extended Kalman filter is used to prevent possible disturbances to search for its laser stripe. Second, to realize the extraction of the profile of welding seam, the least square method is used to fit a sequence of centroids determined by the scanning result of columns displayed on the tracking window. Third, this profile is then qualitatively described and matched using a proposed character string method. It is demonstrated that it maintains real time and is clearly superior in terms of accuracy and robustness, though its real-time performance is not the best. This paper proposes a robust method for automatically identifying and tracking a welding seam.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 08-2018
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 09-2017
No related grants have been discovered for Mohammad Omar Khyam.