• Journal of the Institute of Electronics and Information Engineers
• /
• v.54 no.6
• /
• pp.93-99
• /
• 2017

In this research the TOF (time of flight) of ultrasonic signal is measured using Xilinx's Zynq SoC (system on chip). The TOF is calculated from the difference between periods during which RF (radio frequency) and ultrasonic signals come across a distance, and then travelling distance is obtained by multiplying the TOF by the ultrasonic speed in the air. For this purpose, a ultrasonic pulse is generated from a Zynq's internal ADC, a FIR (finite impulse response) filter, and a Kalman filter. And a RF reference pulse is generated from a RF interface. Based on baremetal multiprocessing, the Kalman filter and the RF interface are c-programmed on Zynq's dual processor cores, with other components fabricated on Zynq's FPGA. With this HW/SW co-design, both lower resource utilization and much smaller designing period were obtained than the HW design. As a design tool, Vivado IDE(integrated design environment) is used to design the whole signal processing system in hierarchical block diagrams.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.12 no.1
• /
• pp.53-60
• /
• 2017

Most of present ultrasonic distance measurement technologies are based on the measurement of the TOF (: Time of Flight), the elapsed time during which the ultrasonic wave travels from its transmitter to receiver, to evaluate the distance the wave travels during that time. In this case, high distance measurement accuracy requires an accurate measurement of TOF. In order to acquire an accurate TOF, this paper proposes a method that produces the TOF by using a mathematical model of the received signal obtained from a mathematical model of ultrasonic transducer. The proposed method estimates the arrival time of the received signal retrospectively by comparing its wave form obtained after triggering point with its mathematical model in the sense of least-square. Experimental result shows that the effect of variation of triggering point can be decreased by implementing the proposed method.

• Journal of Electrical Engineering and Technology
• /
• v.13 no.2
• /
• pp.981-988
• /
• 2018

In order to acquire an accurate TOF, this paper proposes a method that produces TOF by using a mathematical model for the envelope of the received signal obtained from a system dynamic model of ultrasonic transducer. The proposed method estimates the arrival time of the received signal retrospectively by comparing its wave form obtained after triggering point with its mathematical envelope model. Experimental result shows that the error due to variation of triggering point can be dramatically decreased by implementing the proposed method.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2013.06a
• /
• pp.293-298
• /
• 2013

This research develops an ultrasonic sensor to measure the distance in underwater. The ultrasonic transducer transmits an acoustic signal to an object and receives the echo signal reflected from the object. The ultrasonic driver calculates a distance by multiplying the acoustic speed to the time of flight(TOF) which is the time necessary for the acoustic signal to travel from the transducer to the object. We apply a thresholding and a cross correlation methods to detect the TOF and show their results. When an echo pulse is corrupted with noise and its shape is distorted, the cross correlation method is used to find the TOF based on the maximum similarity between the reference and the delayed echo signals. The echoes used for the reference signal are achieved at the different environments, which improves the performance of the sensor. This paper describes the driver of the acoustic sensor and analyzes the performance of sensors in different measurement environments.

• Journal of Sensor Science and Technology
• /
• v.23 no.1
• /
• pp.46-50
• /
• 2014

In this paper, we report a novel algorithm based on phase displacement, which supplements conventional TOF methods for distance measurement using an ultrasonic wave. The proposed algorithm roughly measures the distance between the transmission part and the receiving part by using the initial TOF. Thereafter, the precise distance is determined by measuring the phase displacement value between the synchronizing transmission signal and the signal obtained at the receiving end. A distance measurement experiment using a micrometer was performed to verify the accuracy of the ultrasonic wave sensor system. We found that the mean errors from the one adopting the distance measurement algorithm based on phase displacement varied from a minimum of 0.03 mm to a maximum of 0.09 mm. In addition, the standard deviation varied from a minimum of 0.04 mm to a maximum of 0.07 mm, thus giving a precision of ${\pm}0.1$ mm.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.66 no.8
• /
• pp.1250-1256
• /
• 2017

In this research, a high-performance ultrasonic positioning system is proposed to track the positions of an indoor mobile object. Composed of an ultrasonic sender (mobile object) and a receiver (anchor), the system employs three ultrasonic time-off-flights (TOFs) and trilateration to estimate the positions of the object with an accuracy of sub-centimeter. On the other hand, because ultrasonic waves are interfered by temperature, wind and various obstacles obstructing the propagation while propagating in air, ultrasonic pulse debounce technique and Kalman filter were applied to TOF and position calculation, respectively, to compensate for the interference and to obtain more accurate moving object position. To perform tasks in real time, ultrasonic signals are processed full-digitally with a Zynq SoC, and as a software design tool, Vivado IDE(integrated design environment) is used to design the whole signal processing system in hierarchical block diagrams. And, a hardware/software co-design is implemented, where the digital circuit portion is designed in the Zynq's fpga and the software portion is c-coded in the Zynq's processors by using the baremetal multiprocessing scheme in which the c-codes are distributed to dual-core processors, cpu0 and cpu1. To verify the usefulness of the proposed system, experiments were performed and the results were analyzed, and it was confirmed that the moving object could be tracked with accuracy of sub-cm.

• Journal of Electrical Engineering and Technology
• /
• v.9 no.5
• /
• pp.1753-1761
• /
• 2014

Due to the inherent inhomogeneous and anisotropy nature of the composite materials, the detection of internal defects in these materials with non-destructive techniques is an important requirement both for quality checks during the production phase and in service inspection during maintenance operations. The estimation of the time-of-arrival (TOA) and/or time-of-flight (TOF) of the ultrasonic echoes is essential in ultrasonic non-destructive testing (NDT). In this paper, we used split-spectrum processing (SSP) combined with matching pursuit signal decomposition (MPSD) to develop a dedicated ultrasonic detection system. SSP algorithm is used for Signal-to-Noise Ratio (SNR) enhancement, and the MPSD algorithm is used to decompose backscattered signals into a linear expansion of chirplet echoes and estimate the chirplet parameters. Therefore, the combination of SSP and MPSD (SSP-MPSD) presents a powerful technique for ultrasonic NDT. The SSP algorithm is achieved by using Gaussian band pass filters. Then, MPSD algorithm uses the Maximum Likelihood Estimation. The good performance of the proposed method is experimentally verified using ultrasonic traces acquired from three specimens of carbon fibre reinforced polymer multi-layered composite materials (CFRP).

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.7B
• /
• pp.595-601
• /
• 2006

This study presents an ultrasonic location awareness system for the ubiquitous computing with absolute position. The flight time of ultrasonic waves is determined by a period detecting technique which is able to extend the sensing range compared with traditional methods. For location awareness, ultrasonic waves are sent successively from each ultrasonic transmitter and synchronized by radio frequency (RF) signal, where the transmitting part is fixed and the receiving part is movable. To expand the recognizing range, cell matching technique and coded ultrasonic technique are introduced. The experimentation for various distances is accomplished to verify the used period detecting technique of U-SAT system. The positioning accuracy by using cell matching is also verified by finding the locations of settled points and the usability of coded ultrasonic technique is verified. As a result, the possibility of ultrasonic location awareness system for the ubiquitous computing can be discussed as a pseudo-satellite system with low cost, a high update rate, and relatively high precision, in the places where GPS is not available.

• 제어로봇시스템학회:학술대회논문집
• /
• 2003.10a
• /
• pp.2519-2523
• /
• 2003

Ultrasonic sensors are widely used in mobile robot applications to recognize external environments, because they are cheap, easy to use, and robust under varying lighting conditions. In most cases, a single ultrasonic sensor is used to measure the distance to an object based on time-of-flight (TOF) information, whereas multiple sensors are used to recognize the shape of an object, such as a corner, plane, or edge. However, the conventional sequential driving technique involves a long measurement time. This problem can be resolved by pulse coding ultrasonic signals, which allows multi-sensors to be fired simultaneously and adjacent objects to be distinguished. Accordingly, the current presents a new simultaneous coded driving system for an ultrasonic sensor array for object recognition in autonomous mobile robots. The proposed system is designed and implemented using a DSP and FPGA. A micro-controller board is made using a DSP, Polaroid 6500 ranging modules are modified for firing the coded signals, and a 5-channel coded signal generating board is made using a FPGA. To verify the proposed method, experiments were conducted in an environment with overlapping signals, and the flight distances for each sensor were obtained from the received overlapping signals using correlations and conversion to a bipolar PCM-NRZ signal.

• Journal of Institute of Control, Robotics and Systems
• /
• v.10 no.11
• /
• pp.1028-1036
• /
• 2004

Ultrasonic sensors are widely used in mobile robot applications to recognize external environments by virtue that they are cheap, easy to use, and robust under varying lighting conditions. In most cases, a single ultrasonic sensor is used to measure the distance to an object based on time-of-flight (TOF) information, whereas multiple sensors are used to recognize the shape of an object, such as a comer, plane, or edge. However, the conventional sequential driving technique involves a long measurement time. This problem can be resolved by pulse coding of ultrasonic signals, which allows multi-sensors to be emitted simultaneously and adjacent objects to be distinguished. Accordingly, this paper presents a new simultaneous coded driving system for an ultrasonic sensor array for object recognition in autonomous mobile robots. The proposed system is designed and implemented. A micro-controller unit is implemented using a DSP, Polaroid 6500 ranging modules are modified for firing the coded signals, and a 5-channel coded signal generating board is made using a FPGA. To verify the proposed method, experiments were conducted in an environment with overlapping signals, and the flight distances fur each sensor were obtained from the received overlapping signals using correlations and conversion to a bipolar PCM-NRZ signal.