Yong-Eun Kim

Implementation of FlexRay communication controller protocol with application to a robot system

FlexRay is a new standard of network communication system which provides a high speed serial communication, time triggered bus and fault tolerant communication between electronic devices for future automotive applications. FlexRay communication controller (CC) is the core of the FlexRay protocol specification. In this paper, we first design the FlexRay CC protocol specification and function parts using SDL (Specification and Description Language). Then, the system is re-designed using Verilog HDL based on the SDL source. The FlexRay CC system was synthesized using Samsung 0.35 mum technology. It is shown that the designed system can operate in the frequency range above 80 MHz. In addition, to show the validity of the designed FlexRay system, the FlexRay system is combined with sound source localization system in Robot applications. The combined system is implemented using ALTERA Excalibur ARM EPXA4F672C3. It is shown that the implemented system operates successfully.

Power and Area Efficient Squarer Design

The partial product matrix (PPM) of a parallel squarer is symmetric. To reduce the depth of PPM, it can be folded, shifted and rearranged. In this paper, we present a high performance parallel squarer design method. Also, a fixed-width squarer design method of the proposed squarer is presented. By simulations, it is shown that the proposed squarers lead to up to 17% reduction in area, 10% reduction in propagation delay and 10% reduction in power consumption compared with previous squarers. By using the proposed fixed-width squarers, the area, propagation delay and power consumption can be further reduced up to 30%, 16% and 28%, respectively.

Efficient IFFT design using mapping method

FFT/IFFT processor is one of the key components in the implementation of OFDM systems such as WiBro, DAB and UWB systems. Most of the researches on the implementation of FFT processors have focused on reducing the complexities of multipliers, memory and control circuits. In this paper, to reduce the register size required for IFFT, we propose a new IFFT design method based on a mapping method. By simulations, it is shown that the proposed IFFT design method achieves more than 60% area reduction and much SQNR (Signal-to-Quantization Noise Ration) gain compared with previous IFFT designs.

Automobile Advance Alarm System Based on Monocular Vision Processing

While the interests in intelligent vehicle increase, many people are having concerns about systems that offer the information of distance and relative speed between two cars. This paper presents an algorithm to obtain efficiently the distance between two cars.

Efficient FIR interpolation circuit using supplementary filter

Interpolation filters are widely used in symbol timing recovery systems to interpolate new sample values at arbitrary points between the existing discrete-time samples. Polynomial interpolation computes the coefficients of the polynomial according to the input information to obtain the position value. In this paper, we propose an efficient way to implement the third-order Lagrange interpolation circuit by introducing a supplementary filter. Examples and simulation results show that the proposed approach is more efficient compared to the conventional interpolation methods.

Efficient sound source localization method using region selection

Sound source localization systems in service robot applications estimate the direction of a human voice. Time difference information obtained from a few separate microphones is widely used for the estimation of the sound direction. The cross-correlation function is computed in order to calculate the time difference between the two signals. Inverse cosine function is used when the position of the maximum correlation value is converted to an angle. Because of the nonlinear characteristic of inverse cosine function, the accuracy of the computed angle is varied depending on the position of the specific sound source. In this paper, we propose an efficient sound source localization method using region selection. By the proposed approach, the region from 0° to 180° is divided into three regions and only one of the three regions is selected such that the selected region corresponds to the linear part of the inverse cosine function. Only the selected region is used for the sound source localization. Thus considerable amount of computation time is saved and the accuracy of the computed angle is improved. By simulations, it is shown that the estimation error by the proposed method is only 31% of that of the conventional approach.

Modified CSD group multiplier design for predetermined coefficient groups

Some digital signal processing applications, such as FFT, request multiplications with a group (or, groups) of a few predetermined coefficients. In this paper, based on a grouping method of CSD coefficients, an efficient multiplier design method for predetermined coefficient groups is proposed. In the case of the multiplier design for sine-cosine generator used in direct digital frequency synthesizer(DDFS), it is shown that by the proposed method, area, power and delay time can be reduced by 53.1%, 45.6% and 22.6%, respectively, compared with conventional design. Also, in the case of multiplier design used in 128 point radix-24 FFT, the area, power and delay time can be reduced by 42.9%, 58.5% and 19.7%, respectively.

Constant multiplier design using specialized bit pattern adders

The problem of efficient hardware implementation of multiple constant multiplication (MCM) is encountered in many digital signal processing applications such as FIR filter and linear transform (e.g., DCT and FFT). It is known that efficient solutions based on common subexpression elimination (CSE) algorithm can yield significant improvements in area and power consumption. In this paper, we present efficient implementation method of two common subexpressions (101, 101) in canonic signed digit (CSD) representation. By Synopsys simulations of a radix-24 FFT example, it is shown that the area, speed and power consumption can be reduced up to 21%, 11% and 12%, respectively, by the proposed algorithm.

Sound Source Localization Method Using Region Selection

There are many applications that would be aided by the determination of the physical position and orientation of users. Some of the applications include service robots, video conference, intelligent living environments, security systems and speech separation for hands-free communication devices (Coen, 1998; Wax & Kailath, 1983; Mungamuru & Aarabi, 2004; Sasaki et al., 2006; Lv & Zhang 2008). As an example, without the information on the spatial location of users in a given environment, it would not be possible for a service robot to react naturally to the needs of the user. To localize a user, sound source localization techniques are widely used (Nakadai et al., 2000; Brandstein & Ward, 2001; Cheng & Wakefield, 2001; Sasaki et al., 2006). Sound localization is the process of determining the spatial location of a sound source based on multiple observations of the received sound signals. Current sound localization techniques are generally based upon the idea of computing the time difference of arrival (TDOA) information with microphone arrays (Knnapp & Cater, 1976; Brandstein & Silverman, 1997). An efficient method to obtain TDOA information between two signals is to compute the cross-correlation of the two signals. The computed correlation values give the point at which the two signals from separate microphones are at their maximum correlation. When only two isotropic (i.e., not directional as in the mammalian ear) microphones are used, the system experiences front-back confusion effect: the system has difficulty in determining whether the sound is originating from in front of or behind the system. A simple and efficient method to overcome this problem is to incorporate more microphones (Huang et al., 1999). Various weighting functions or pre-filters such as Roth, SCOT, PHAT, Eckart filter and HT can be used to increase the performance of time difference estimation (Knnapp & Cater, 1976). However, the performance improvement is achieved with the penalty of large power consumption and hardware overhead, which may not be suitable for the implementation of portable systems such as service robots. In this chapter, we propose an efficient sound source localization method under the assumption that three isotropic microphones are used to avoid the front-back confusion

Efficient Squarer Design Using Group Partial Products

The partial product matrix (PPM) of a squarer is symmetric. To reduce the depth of PPM, it can be folded, shifted and rearranged. In this paper, we propose a squarer design method using partial product grouping method. The proposed squarers lead to up to 24.7%, 24.4% and 6.7% reduction in area, power consumption and propagation delay compared with conventional squarers.