• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.6
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• pp.55-61
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• 2013

In this paper, we describe design and implementation of audio encoder/decoder for voice synthesis. It uses the encoding of difference value of successive samples instead of the original sample value. and has the compression ratio of 4. The function is verified by using FPGA and the performance is measured by the fabricated chip using $0.35{\mu}m$ standard CMOS process. The system clock is 16.384MHz. The measured THD+n is from -40dB to -80dB with frequency variation and the power consumption is about 80mW. It is suited for the mobile application of high audio quality and low power consumption.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.5
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• pp.611-618
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• 1993

A common requirement in digital communication systems is the generation of prescribed shape. The purpose of this paper is implement an efficient digital waveform filter by using the look-up table in the RDS(Radio Data System) encoder. And it has been shown that transmitted data can be recovered without an error. In order to implement an efficient waveform filter, the control algorithm is designed. For the purpose of composing an IC, the digital waveform filter is implemented by using the discrete elements. Moreover in this paper it has been proved that the proposed digital waveform filter can be applied to the RDS encoder.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.2
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• pp.177-184
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• 2013

This paper proposes an enhanced Simultaneous Localization and Mapping (SLAM) algorithm based on matching laser image and Extended Kalman Filter (EKF). In general, laser information is one of the most efficient data for localization of mobile robots and is more accurate than encoder data. For localization of a mobile robot, moving distance information of a robot is often obtained by encoders and distance information from the robot to landmarks is estimated by various sensors. Though encoder has high resolution, it is difficult to estimate current position of a robot precisely because of encoder error caused by slip and backlash of wheels. In this paper, the position and angle of the robot are estimated by comparing laser images obtained from laser scanner with high accuracy. In addition, Speeded Up Robust Features (SURF) is used for extracting feature points at previous laser image and current laser image by comparing feature points. As a result, the moving distance and heading angle are obtained based on information of available points. The experimental results using the proposed laser slam algorithm show effectiveness for the SLAM of robot.

• IEMEK Journal of Embedded Systems and Applications
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• v.12 no.4
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• pp.213-221
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• 2017

Utilizing the existing polishing robot prevents unrestricted change of direction, driving, and identification of driving pathway. To overcome this barrier, driving mechaism has been designed with Omniwheels with encoders and RSSI method of beacon system has been utilized to identify the driving path by position recognition. Due to the wheel characteristics, the Omniwheel mobile robot generates greater slip than the conventional mobile robot, which reduces its driving accuracy. Therefore, to improve the driving accuracy, the localization is conducted through the fusion of encoder and RSSI of beacon data to compensate for the errors caused by Dead Reckoning and inaccuracy of sensors. Finally, the localization accuracies of the proposed and conventional indoor localization method are compared to show effectiveness of the proposed driving control for a polishing robot.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.3
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• pp.330-338
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• 2011

Odometry is the critical factor to estimate the location of the robot. In the mobile robot with wheels, odometry can be performed using the information from the encoder. However, the information of location in the encoder is inaccurate because of the errors caused by the wheel's alignment or slip. In general, visual odometer has been used to compensate for the kinetic errors of robot. In case of using the visual odometry under some robot system, the kinetic analysis is required for compensation of errors, which means that the conventional visual odometry cannot be easily applied to the implementation of the other type of the robot system. In this paper, the novel visual odometry, which employs only the single camera toward the ground, is proposed. The camera is mounted at the center of the bottom of the mobile robot. Feature points of the ground image are extracted by using median filter and color contrast filter. In addition, the linear and angular vectors of the mobile robot are calculated with feature points matching, and the visual odometry is performed by using these linear and angular vectors. The proposed odometry is verified through the experimental results of driving tests using the encoder and the new visual odometry.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.112-115
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• 2008

In this paper, we propose H.264 High Profile Encoder Intra Prediction module. This designed module can be operated in 306 cycle for one-macroblock. To verify the Encoder architecture, we developed the reference C from JM 13.2 and verified the our developed hardware using test vector generated by reference C. We adopt plan removal and SAD calculation to reduce the Hardware cost and cycle. The designed circuit can be operated in 133MHz clock system, and has 250K gate counts using TSMC 0.18um process including SRAM memory.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.10
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• pp.831-835
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• 2020

By automatically generating HDL codes from C/C++ source codes, HLS makes it possible to shorten FPGA system developing period through easy timing control and structure change. We designed LDPC encoder for telemetry standard 106-17 with Xilinx Vivado HLS and showed hardware structure can be easily adapted for different purposes through minor C code modification. Synthesis results targeting Spartan-7 xc7s100 device are presented for throughput and hardware complexity comparison.

• Proceedings of the KIPE Conference
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• 2003.11a
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• pp.51-55
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• 2003

In this paper, the authors propose a new high performance Built-in Type spindle motor drive using vector-controlled technique at 15,000 r/min. Control method is changed by variation of motor speed in a conventional Built-in type spindle drive. In the drive system to be presented, the conventional vector control is used in the low-speed range, and the vector control without encoder is used in the high-speed range. Furthermore, in order to drive the motor from 0 to 15,000 rpm smoothly, the vector control with encoder in the low-speed range (from 0 to 8,000 rpm) is utilized and the vector control without encoder in the high-speed range (from 8,000 to 15,000 rpm) is utilized. This paper describes problem of control method in conventional spindle drive and proposes control method as variation of motor speed

• Journal of Power Electronics
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• v.9 no.2
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• pp.224-231
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• 2009

The induction motor rotor fault diagnosis system using current signals, which are measured using an axis-transformation method, is presented in this paper. In inverter-fed motor drives, unlike line-driven motor drives, the stator currents are rich in harmonics; therefore fault diagnosis using stator current is not trivial. The current signals for rotor fault diagnosis need precise and high resolution information, which means the diagnosis system demands additional hardware such as a low pass filter, high resolution ADC, and encoder, etc. The proposed axis-transformation method with encoder and without encoder is expected to contribute to a low cost fault diagnosis system in inverter-fed motor drives without the need for any additional hardware. In order to confirm the validity of the developed algorithms, various experiments for rotor faults are tested and the line current spectrum of each faulty situation using Park transformation is compared with the results obtained from fast Fourier transforms.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.9A
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• pp.920-927
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• 2006

There are three critical considerations in developing a PCM telemetry encoder to be installed in an artillery projectile. The first is the performance consideration, such as sampling rate and data transmission rate. The second is the size consideration due to the severely limited installation space in an artillery projectile and the last is the power consumption consideration due to limitations of the munition's power supply. To meet these three considerations, the best alternative is a one-chip solution. Using a commercially available TMS320F2812 DSP, we have implemented a 30-channel PCM telemetry encoder to process randomized data frames, composed of 16-channel analog data, 14-channel digital data and 2-frame synchronization channels per data frame at 10Mbps transmitting baud rate.