Now showing 1 - 7 of 7
  • Publication
    Ultrasonic Orientation-Location Algorithm based on ToA and AoA Measurements
    This paper proposes a novel system which provides 3-axis orientation and 3D location estimation for a Mobile Device based on Time of Flight (ToF) and Angle of Arrival (AoA) measurements using ultrasonic signals. Robustness is provided to the system by means of a Slow Frequency-Hop Spread Spectrum modulation and a robust 2D AoA estimation method with a Uniform Circular Array (UCA). In simulation, the system shows an accuracy of 1.7 degrees in the orientation estimates and location estimates under 1cm in 95% of cases under conditions of noise and reverberation.
      424Scopus© Citations 2
  • Publication
    Accuracy of Spread Spectrum Techniques for Ultrasonic Indoor Location
    This paper presents an assessment of the accuracy of impulsive and spread spectrum based algorithms for indoor ultrasonic location. Ultrasonic location systems have been proposed for pervasive computing applications. Previous systems have focused on the use of impulsive and Direct Sequence Spread Spectrum (DSSS) signalling. The use of Frequency Hopped Spread Spectrum (FHSS) signalling has not been previously studied for ultrasonic location. It is shown herein that FHSS outperforms DSSS and impulsive signalling under conditions of noise and reverberation. The accuracy of location for FHSS is shown to be twice that of DSSS under typical conditions. FHSS also provides opportunities for simplified transducer construction.
      658Scopus© Citations 21
  • Publication
    Robust Ultrasonic Spread Spectrum Positioning System Using a AoA/ToA Method
    This paper proposes a novel hybrid Time of Arrival (ToA) and Angle of Arrival (AoA) based system for 3D indoor location using ultrasonic spread spectrum signals. The proposed system differs from previously proposed hybrid systems in several ways - the mobile devices determines its own position, the consequent orientation problem is solved and the system uses spread spectrum techniques to improve robustness to noise and multipath. The system uses an inclinometer to allow the mobile to determine its own position. This paper compares the performance of the proposed hybrid system with that of a conventional ToA- only system. The hybrid system is found to reduce the number of base stations needed for 3D location of the mobile device, from three to two, and to provide more accurate location estimates under conditions of typical noise and room reverberation.
      402Scopus© Citations 3
  • Publication
    High-precision robust broadband ultrasonic location and orientation estimation
    This paper presents an indoor broadband ultrasonic system for estimation of a mobile device’s 3-D location and three-axis orientation using beacons. It presents the first implementation and characterization of a real frequency hopping spread spectrum-based ultrasonic positioning system, a novel application of uniform circular array angle of arrival estimation techniques to indoor location-orientation estimation and a novel hybrid algorithm for location-orientation estimation. The performance of the system was assessed experimentally. The system has been shown to provide better accuracy, robustness to noise and multipath than other previously reported indoor ultrasonic location or orientation estimation systems with comparable range in the typical office environment tested. The prototype provided location estimates with an error of less than 1.5 cm and and error of less than 4.5 in the yaw, 3 in the pitch and 3.5 in the roll, in 95% of cases.
      1083Scopus© Citations 82
  • Publication
    Low Cost, Wideband Ultrasonic Transmitter and Receiver for Array Signal Processing Applications
    This paper presents a low-cost, wideband ultrasonic transmitter for in-air ultrasonic applications based on a conventional narrowband piezoceramic transducer with a LR circuit modification. An analytic method for calculation of the optimum circuit parameters for bandwidth expansion of the ceramic ultrasonic transmitter is described, together with experimental data proving the viability of the method. A low cost wideband ultrasonic receiver array is also presented. The results of the first characterization of MEMs microphones in the ultrasonic band and their use in a sensor array for ultrasonic Array Signal Processing applications is presented. The study presents examples of prototype performance in ultrasonic indoor applications.
      2798Scopus© Citations 21
  • Publication
    Effect of Compiler Optimizations on DSP Processor Power and Energy Consumption
    This paper examines the effect of compiler optimizations on the energy usage and power consumption of DSP processor, specifically to the Texas Instruments TMS320VC5510. The effects of different levels of general and specific optimization on the energy and power consumption are measured for this processor. Given the special characteristics of DSP programs, the benchmark routines were selected from DSPStone, and some typical DSP applications. Finally, Texas Instruments library routines are compared with the compiled versions. The paper provides an analysis of the results together with recommendations for improving performance. The binaries used in this study were generated using the Texas Instrument C/C++ Compiler, which allows control over the whole set of optimizations.
  • Publication
    Non-Line of Sight Mitigation using a Measurement and Positioning Filtering Algorithm
    In recent years, research interest in location systems has increased due to the emergence of mobile computing devices and the promise of Ubiquitous Computing. This paper considers the problem arising in ultrasonic location systems of Non-Line of Sight (NLOS) between Base Stations and Mobile Devices, which can give significant location errors. Herein, a Dual Kalman Filtering method is proposed to mitigate NLOS effects, using an a-priori partial knowledge of the ultrasonic signals. The main advantage of this method is that the first filter provides a set of filtered ranges that mitigates the NLOS ranging error, while the second filter, by taking these measurements, provides a second positioning filtering that mitigates the overall positioning error. The method is shown to reduce location errors providing a maximum error in location of 9cm.