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Dive into the research topics where Koji Ozawa is active.

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Featured researches published by Koji Ozawa.


Proceedings of the IEEE | 2007

Driver Modeling Based on Driving Behavior and Its Evaluation in Driver Identification

Chiyomi Miyajima; Yoshihiro Nishiwaki; Koji Ozawa; Toshihiro Wakita; Katsunobu Itou; Kazuya Takeda; Fumitada Itakura

All drivers have habits behind the wheel. Different drivers vary in how they hit the gas and brake pedals, how they turn the steering wheel, and how much following distance they keep to follow a vehicle safely and comfortably. In this paper, we model such driving behaviors as car-following and pedal operation patterns. The relationship between following distance and velocity mapped into a two-dimensional space is modeled for each driver with an optimal velocity model approximated by a nonlinear function or with a statistical method of a Gaussian mixture model (GMM). Pedal operation patterns are also modeled with GMMs that represent the distributions of raw pedal operation signals or spectral features extracted through spectral analysis of the raw pedal operation signals. The driver models are evaluated in driver identification experiments using driving signals collected in a driving simulator and in a real vehicle. Experimental results show that the driver model based on the spectral features of pedal operation signals efficiently models driver individual differences and achieves an identification rate of 76.8% for a field test with 276 drivers, resulting in a relative error reduction of 55% over driver models that use raw pedal operation signals without spectral analysis


IEICE Transactions on Information and Systems | 2006

Driver Identification Using Driving Behavior Signals

Toshihiro Wakita; Koji Ozawa; Chiyomi Miyajima; Kei Igarashi; Katunobu Itou; Kazuya Takeda; Fumitada Itakura

In this paper, we propose a driver identification method that is based on the driving behavior signals that are observed while the driver is following another vehicle. Driving behavior signals, such as the use of the accelerator pedal, brake pedal, vehicle velocity, and distance from the vehicle in front, are measured using a driving simulator. We compared the identification rate obtained using different identification models and different features. As a result, we found the nonparametric models is better than the parametric models. Also, the drivers operation signals were found to be better than road environment signals and car behavior signals. The identification rate for thirty driver using actual vehicle driving in a city area was 73%.


ieee intelligent transportation systems | 2005

Driver identification using driving behavior signals

Toshihiro Wakita; Koji Ozawa; Chiyomi Miyajima; Kei Igarashi; Katsunobu Itou; Kazuya Takeda; Fumitada Itakura

In this paper, we propose a driver identification method that is based on the driving behavior signals that are observed while the driver is following another vehicle. Driving behavior signals, such as the use of the accelerator pedal, brake pedal, vehicle velocity, and distance from the vehicle in front, are measured using a driving simulator. We compared the identification rate obtained using different identification models and different features. As a result, we found the nonparametric models is better than the parametric models. Also, the drivers operation signals were found to be better than road environment signals and car behavior signals. The identification rate for thirty driver using actual vehicle driving in a city area was 73%.


Lecture Notes in Computer Science | 2005

Parametric versus non-parametric models of driving behavior signals for driver identification

Toshihiro Wakita; Koji Ozawa; Chiyomi Miyajima; Kazuya Takeda

In this paper, we propose a driver identification method that is based on the driving behavior signals that are observed while the driver is following another vehicle. Driving behavior signals, such as the use of of the accelerator pedal, brake pedal, vehicle velocity, and distance from the vehicle in front, are measured using a driving simulator. We compared the identification rate obtained using different identification models and different features. As a result, we found the non-parametric models to be better than the parametric models. Also, the drivers operation signals were found to be better than road environment signals and car behavior signals.


information sciences, signal processing and their applications | 2005

Modeling of individualities in driving through spectral analysis of behavioral signals

Koji Ozawa; Toshihiro Wakita; Chiyomi Miyajima; Katsunobu Itou; Kazuya Takeda

Driving behavior modeling using such driving signals as velocity, following distance, and gas or brake pedal operations, has been investigated for accident prevention and vehicle design. Driving behaviors are different among drivers, and research on driver modeling has also been carried out from different points of view in cognitive and engineering approaches. In this paper, driver’s characteristics in driving behaviors are modeled with a Gaussian mixture model (GMM) using “cepstral features” obtained through spectral analysis of gas pedal operation signals. The GMM driver model based on cepstral features is evaluated in driver identification experiments and compared with a conventional GMM driver model that uses raw driving signals without spectral analysis. Experimental results show that the proposed driver model achieves an 89.6% driver identification rate, resulting in 61% error reduction over the conventional driver model.


Archive | 2007

Driver Identification Based on Spectral Analysis of Driving Behavioral Signals

Yoshihiro Nishiwaki; Koji Ozawa; Toshihiro Wakita; Chiyomi Miyajima; Katsunobu Itou; Kazuya Takeda

In this chapter, driver characteristics under driving conditions are extracted through spectral analysis of driving signals. We assume that characteristics of drivers while accelerating or decelerating can be represented by “cepstral features” obtained through spectral analysis of gas and brake pedal pressure readings. Cepstral features of individual drivers can be modeled with a Gaussian mixture mode! (GMM). Driver models are evaluated in driver identification experiments using driving signals of 276 drivers collected in a real vehicle on city roads. Experimental results show that the driver model based on cepstral features achieves a 76.8 % driver identification rate, resulting in a 55 % error reduction over a conventional driver model that uses raw gas and brake pedal operation signals.


Archive | 2006

Driving Action Estimating Device, Driving Support Device, Vehicle Evaluating System, Driver Model Creating Device, and Driving Action Determining Device

Kazuya Takeda; Katunobu Itou; Chiyomi Miyajima; Koji Ozawa; Hirokazu Nomoto; Kazuaki Fujii; Seiichi Suzuki


international conference on acoustics, speech, and signal processing | 2006

Cepstral Analysis of Driving Behavioral Signals for Driver Identification

Chiyomi Miyajima; Yoshihiro Nishiwaki; Koji Ozawa; Toshihiro Wakita; Katsunobu Itou; Kazuya Takeda


Archive | 2011

Drive behavior estimating device, drive supporting device, vehicle evaluating system

Katunobu Itou; Hirokazu Nomoto; Kazuaki Fujii; Koji Ozawa; Kazuya Takeda; Seiichi Suzuki; Chiyomi Miyajima


Archive | 2006

Drive behavior estimating device, drive supporting device, vehicle evaluating system, driver model making device, and drive behavior judging device

Kazuya Takeda; Katunobu Itou; Chiyomi Miyajima; Koji Ozawa; Hirokazu Nomoto; Kazuaki Fujii; Seiichi Suzuki

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