■Faculty | Department of Robotics / Research Institute of Fundamental Technology for Next Generation / Graduate School of System Enginnering |

■Position | Associate Professor |

■Degree | |

■Commentator Guide | https://www.kindai.ac.jp/meikan/413-sakai-hideki.html |

■URL | |

Last Updated :2020/04/03

- 2012 04 , - 現在, Faculty of Engineering, Kindai University

- Manufacturing technology (mechanical, electrical/electronic, chemical engineering), Machine elements and tribology
- Manufacturing technology (mechanical, electrical/electronic, chemical engineering), Design engineering
- Social infrastructure (civil Engineering, architecture, disaster prevention), Civil engineering (planning and transportation)

- vehicle dynamics

- Fundamental study on yaw resonance mode (Relationship between yaw resonance phenomenon and evaluation term s of driver s interpreted based on resonance phenomenon in a simple model), Hideki SAKAI, Oct. 2018 , RefereedSummary:This paper starts with describing a method of deriving the resonance mode of a pendulum utilizing its equation of motion. This resonance mode is that the equilibrium position of the pendulum locates the vertical plane including its fixed point and the mass accelerates in proportion to the distance from the equilibrium position to its mass. Further, the equation of motion of vehicles was converted to a form conforming to the equation of motion of the pendulum. As a result, it was found that the equilibrium position of yaw resonance is the extension line of the vehicle speed vector at the front wheel position. Moreover, it turned out that its rear wheel accelerates toward this extension line in proportion to the distance from this extension line to the rear wheel is the yaw resonance mode under a special condition. Finally, the step steering response was considered. At the moment of steering input, the mode of the yaw lead time constant appears, and then the yaw resonance mode becomes apparent. Hence, the yaw resonance is revealed in the latter half of the transient response. Therefore, it is considered that the yaw natural frequency is suitable as a metric of the latter half behavior of the transient response.
- Fundamental and theoretical consideration for reduction of hunting of wheelset, Hideki SAKAI, The Dynamics of Vehicles on Roads and Tracks, The Dynamics of Vehicles on Roads and Tracks, 2, 999 - 1004, 2018
- The Dynamics of Vehicles on Roads and Tracks, Hideki SAKAI, The Dynamics of Vehicles on Roads and Tracks, The Dynamics of Vehicles on Roads and Tracks, 1, 335 - 340, 2018
- Theoretical consideration to a mode in planar motion against transient steering input, Hideki SAKAI, The Dynamics of Vehicles on Roads and Tracks, The Dynamics of Vehicles on Roads and Tracks, 1, 185 - 192, 2018
- A theoretical consideration to negative damping of hunting of wheelset, 83(854), Oct. 2017 , Refereed
- Fundamental study of cornering limit characteristics of motorcycles during braking and driving, Hideki SAKAI, 83(854), Oct. 2017 , RefereedSummary:Sport riding performance on racing circuits and other locations is seen as an important element in the marketability of motorcycles. In sport riding, some riders start a turn while braking or start acceleration (driving) while turning. Furthermore, the braking aspect of sport riding performance is also critical to accident avoidance performance since it is similar to that of the braking during cornering performance. Consequently, in this paper a fundamental study was carried out to determine methods for improving the cornering limit performance during driving and braking. In the case of four-wheeled vehicles, the G-G diagram is used as a method to indicate the cornering limit performance. In the G-G diagram the longitudinal driving and lateral driving of the vehicle are set as the two axes. Therefore, the first part of this paper proposes a G-G diagram for motorcycles theoretically. In the latter part of this paper, this paper discusses the braking force distribution ratio of front wheel that would maximize the maximum lateral driving, the influence of the normal load distribution ratio of front wheel on the limit cornering property and the influence of the height of the center of gravity on it. From these result, this paper proposes methods for improving the cornering limit performance while braking.
- Automobile plane-motion model including roll motion: Second report (Taking into consideration phase difference of cornering forces between front and rear wheels), Hideki SAKAI, Transactions of the JSME (in Japanese), Transactions of the JSME (in Japanese), 82(843), 1 - 17, Nov. 2016 , RefereedSummary:The roll motion of the vehicle has an effect on the yaw natural frequency. Because the yaw natural frequency formula considering this effect is the solution to a quartic equation, the expression of the formula is thought to be complex and incomprehensible. Accordingly, a seemingly comprehensible approximate formula was suggested in the former paper. In this approximation process, it was assumed that the cornering forces of the front and rear wheels are generated simultaneously. On the other hand, a later report have indicated that the yaw resonance when the vehicle drives at a certain speed has a cornering forces phase difference of 90 degrees between the front and rear wheels. Therefore this paper formulates the yaw natural frequency and yaw damping ratio assuming the phase difference to be 90 degrees. As results of that, qualitatively, the design variables that dominate the characteristic equation are appropriately included in the yaw natural frequency and yaw damping ratio formulas, and quantitatively, the approximation error is reduced. Consequently, these formulas are believed to be more appropriate than the previously proposed formulas. These formulas indicate that, when the load distribution ratio of the front wheels becomes larger, the yaw natural frequency decreases and the yaw damping ratio increases. In addition, this paper also indicates the scope of these approximate formulas quantitatively.
- A Theoretical Study on Dynamical Weave of Wheel Set (Formulas of Natural Frequencies and Damping Ratios Taken Account of Creep Coefficient and Mass), Hideki SAKAI, 7, 73 - 76, Jul. 2016
- Fundamental study of cornering limit characteristics during braking and driving, Hideki SAKAI, 82(839), Jul. 2016 , RefereedSummary:The G-G diagram is one way of expressing the cornering limit during braking or driving. When limit driving data is plotted on a graph with the 2 axes representing longitudinal acceleration and lateral acceleration, the shape of the graph indicates the cornering limit. Although the theoretical outline with a one-wheel model is a circle, the shape on the braking side of a G-G diagram which uses actual measured data is similar to a pentagon. As a result, the basic shape of the diagram is unknown. Therefore this paper proposes a graphical method which uses a two-wheel model to explicitly describe the mechanism that determines the G-G diagram shape. This graphical method is as follows. First, the provisional cornering limit line for the front wheel is plotted in the G-G diagram, ignoring the rear wheel cornering limit. Second, the provisional rear wheel cornering limit is plotted in the G-G diagram, ignoring the front wheel cornering limit. Third, the lower of the two cornering limit lines becomes the shape of the G-G diagram. The reason that the braking-side shape of actual measured data looks like a pentagon is due to the fact that these lines cross each other at two points. Furthermore, this paper describes the vehicle behavior when the diagram shape is the front wheel cornering limit line as “plow”, and the behavior when the shape is the rear wheel line as “spin”. Finally, this paper explains that the cornering limit increases in the order of rear-engine rear-wheel drive (RR), front-engine rear-wheel drive (FR), and front-engine front-wheel drive (FF) vehicles due to the effects of the engine position and position of the drive wheels.
- Damping Control to Enhance Transient Cornering Feeling using Kalman Filter, Hideki SAKAI, International Symposium of Vehicle System Dynamics 2015 Proceedings, International Symposium of Vehicle System Dynamics 2015 Proceedings, 585 - 94, 2015
- System to Detect Decrease in Driver’s Lane-Keeping Ability within Several Seconds by Inverse Driver Model, Hideki SAKAI, International Symposium of Vehicle System Dynamics 2015 Proceedings, International Symposium of Vehicle System Dynamics 2015 Proceedings, 789 - 798, 2015
- A fundamental study of dynamic behavior of vehicles with unstable region under force control, Hideki SAKAI, 81(823), 14, 2015 , RefereedSummary:The primary method of improving steering dynamic response performance is expected to involve position control. However

the driver uses not only the position of the steering wheel but also torque for control. It has been pointed out that particularly

in regions that are close to straight-line driving, torque is the primary means of steering control. Therefore in order to achieve

better high-quality dynamic response, it will be necessary to set higher natural frequencies and damping ratios for force

control. A universal method for achieving this can be achieved by examining the symbolic expressions for these factors.

Force control natural frequencies and damping ratios have been formularized for stable vehicles at all driving speeds.

However these formulas cannot be used for vehicles which have unstable regions, and in fact there are vehicles which have

such unstable regions. This paper examines a method of setting higher natural frequencies and damping ratios in order to

improve the quality of dynamic response characteristics for vehicles that have unstable regions. I first envision a vehicle with

neutral steering and steering system damping of 0, and confirm that the characteristic formula is a fourth-order equation for

the Laplacian operator s. Next I show that when s is converted to a certain variable, the characteristic formula is written as a

biquadratic equation for that variable. By solving this biquadratic equation, the damped natural frequencies and damping

ratios are formularized. By considering these formulas, I show that increasing the cornering coefficient is a method that can

simultaneously increase the damped natural frequency and damping ratio. I also show that this method can be applied to

under-steer vehicles and vehicles which have steering system damping, and finally demonstrate the utility of this method with

a time history response in transitional steering. - A Study on Vehicle Response under Force Control, 44(6), 1013 - 1020, Nov. 2013 , Refereed
- Method for Recognition of Numbers on Speed Limit Signs Utilizing an Eigen Space Method Based on the KL Transform, 2(4), 65 - 73, Sep. 2013 , Refereed
- A Numerical Study on Dynamic Behavior of Steering System and Body System under Force Control, 44(3), 843 - 849, May 2013 , Refereed
- Relatonship between Tire Properties and Stability and Control, 67(4), 27 - 32, Apr. 2013
- A Physical Interpretation of Lead Time Constant of Yaw Angular Velocity in Planar Motion of Automobile, 79(802), 456 - 467, 2013 , RefereedSummary:This paper discusses lead time constant of yaw angular velocity based on equations of motion of automobiles in

planar motion. However, the equations of motion are too complex to be interpreted because the steering angle input

generates two variables, lateral and yaw angular accelerations simultaneously. Under reasonable assumption, I derive an

equivalent transformation models that generates only one acceleration value from the equations of motion. To generate

only one variable against steering input, rigid body of an automobile is replaced by two particles located at the front and

rear axles. The equations of motion of the equivalent transformation models imply a mechanism of automobiles

transient behavior as follows. Steering angle input causes a yaw angular acceleration around the rear axle. This

acceleration changes into a yaw angular velocity by time integration. The yaw angular velocity causes an attitude

angular velocity of the rear axle. The velocity changes into an attitude angle at the rear axle by time integration. This

attitude angle generates a yaw angular acceleration as restoring yaw moment. In this equivalent transformation models,

lead time constant of the yaw angular velocity implies time difference between the yaw angular velocity and attitude

angle at the rear axle. Therefore the lead time constant is suitable for criteria of behavior of the automobile at the rear

axle. Furthermore the equations of motion will introduce a control law to improve automobile dynamic behaviors. - Stability under Force Control and its Index, 44(2), 441 - 448, 2013 , Refereed
- Damping Control to Enhance Transient Cornering Feel - Control to Synchronize Piting with Rolling Utilized Kalman Filter -, 43(3), 709 - 716, May 2012 , Refereed
- Interative Modeling Process of Driver-Agent for Evaluation of Preventive Safety Systems - Application to ASSTREET (Advanced Safety System & Traffic REaltime Evaluation Tool)-, 42(4), 985 - 992, Jul. 2011 , Refereed
- The Development of The Tire Side Force Model Considering The Dependence of Surface Temperature of Tire, Vehicle System Dynamics, Vehicle System Dynamics, 41(Suppl), 361 - 370, Apr. 2008 , Refereed
- Enhancement of Vehicle Dynamic Behavior Based on Visual and Motion Sensitivity, 38(2), 13 - 18, Mar. 2007 , Refereed
- 感覚に基づいた車両運動特性の強調（第２報） -旋回感覚の強調-, Mar. 2007 Summary:

Vehicle body movements that occur during cornering have a strong influence on the evaluation of ride and handling. As a first step, we analyze subjective comments from trained drivers and find that the sense of vision played a major part in cornering feel. As a result of quantitative evaluations, we hypothesize that smaller time lag between roll angle and pitch angle made cornering feel better. We perform a human sensitivity evaluation, which confirmed this hypothesis. Given this result, we derive analytical equations for the roll center kinematics and the damping characteristics, in order to find a theoretical condition for the time lag of 0sec (giving a good cornering feel). We verify this by experiment. - Improvement of Roll Feeling Based on Visual Sensitivity, Apr. 2006
- Development of a tire force model incorporating the influence of the tyre surface temperature, MIZUNO M, SAKAI H, OYAMA K, ISOMURA Y, Vehicle System Dynamics, Vehicle System Dynamics, 71(711), 3208 - 3215, Nov. 2005 , Refereed
- New Model of Tire Overturning Moment Characteristics and Analysis of Their Influence on Vehicle Rollover Behavior, T. Takahashi, M. Hada, K. Oyama, H. Sakai, Vehicle System Dynamics, Vehicle System Dynamics, 42(1,2), 109 - 118, May 2004 , Refereed
- Development of torsion beam rear suspension with toe control links, H. Shimatani, S. Murata, K, Watanabe,T. Kaneko, H. Sakai, SAE Transactions - Journal of Passenger Car, SAE Transactions - Journal of Passenger Car, 108, 18 - 22, 1999 , Refereed
- Theoretical consideration of relation of rear-wheel skid to steering inputs, Hideki SAKAI, SAE Transactions Journal of Passenger Cars, SAE Transactions Journal of Passenger Cars, 106, 504 - 524, 1997 , Refereed

- Automotive vehicle dynamics, Hideki SAKAI, 単著, 2015 12 , 9784627691117

- Design method of suppressing hunting oscillations focusing on its damping ratio, Hideki SAKAI, 11th International conference on railway bogies and running gears, 2019 09 10
- Influence of roll on yaw natural frequency, Hideki SAKAI, IAVSD2019, 2019 08 15
- Theoretical and Fundamental Consideration to Accord between Self-Steer Speed and Rolling in Maneuverability of Motorcycles, Hideki SAKAI, TRANSLOG2018, 2018 12 06
- 9 Theoretical and Fundamental Consideration to Accord between Self-Steer Speed and Rolling in Maneuverability of Motorcycles, Hideki SAKAI, SETC2018, 2018 11 08
- Theoretical and Fundamental Consideration to Accord between Self-Steer Speed and Rolling in Maneuverability of Motorcycles, Hideki SAKAI, SETC2018, 2018 11 08 , SAE
- Prediction of Yaw Natural Frequency Taking Roll Motion into Account, Hideki SAKAI, IAVSD2017, 2017 08 17
- Fundamental and Theoretical Consideration for Reduction of Hunting of Wheel Set, Hideki SAKAI, IAVSD2017, 2017 08 15
- Theoretical Consideration to a Mode in Planar Motion Against Transient Steering Input, Hideki SAKAI, IAVSD2017, 2017 08 15
- Limit of cornering of motorcycle, Hideki SAKAI, TRANSLOG2016, 2016 11 30 Summary:In the case of four-wheeled vehicles, as a method to indicate the cornering limit performance, the G-G diagram is used. In a G-G diagram the longitudinal acceleration and lateral acceleration of the vehicle are set as the two axes. A visible outline of the data when the vehicle is being driven at the limit is drawn on these axes to show the height of the cornering limit. Further, another type of G-G diagram that also indicates which of the front or rear wheels have reached their limit has been proposed. Since the height of the cornering limit, as well as which of the wheels has reached the limit at that time will all be discussed for the cornering limit performance of the motorcycle, it was determined that this G-G diagram should also be suitable for studying motorcycles. However, this G-G diagram cannot be applied to motorcycles as is. This is because the yaw moment balance conditions are different for motorcycles and four-wheeled vehicles. During the cornering of a four-wheeled vehicle, there are two yaw moments acting around the center of gravity of the vehicle due to the cornering force of the front wheels and the rear wheels. However, during the cornering of a motorcycle, there is another yaw moment that acts on the vehicle in addition to these two yaw moments. This third yaw moment is due to a braking and driving force. Therefore, in this paper, the three moments acting on the motorcycle will be converted into the two moments that act on a four-wheeled vehicle so that this G-G diagram can be applied to motorcycles. Further, the front wheel braking force distribution ratio that would produce the maximum height of the cornering limit was studied to propose a criterion assuming combined brake system (CBS) control during cornering.
- A Consideration to Hunting of Wheel Set, Hideki SAKAI, TRANSLOG2016, 2016 11 30 Summary:In order to obtain insight about weave phenomenon of wheel set of rail vehicle, this paper starts with formulating its natural frequencies and damping ratios. Interpreting these formulas, this paper points out that larger ratio of creep coefficient normalized by wheel set mass reduces the weave at lower speed than a given speed and the smaller ratio does it at higher speed.
- Optimal Ratio of Braking Forces Distribution for Improvement Limit Cornering Behavior during Braking, Hideki SAKAI, Bicycle & Motorcycle Dynamics Symposium 2016, 2016 09
- A Theoretical Study on Fundamental of Vehicle Behavior under Force Control, Hideki SAKAI, TSME-ICOM, 2015 12
- System to Detect Decrease in Driver’s Lane-Keeping Ability within Several Seconds by Inverse Driver Model, Hideki SAKAI, International Symposium of Vehicle System Dynamics 2015, 2015 08
- Damping Control to Enhance Transient Cornering Feeling using Kalman Filter, Hideki SAKAI, International Symposium of Vehicle System Dynamics 2015, 2015 08
- Design for Vehicle Stability under Force Control, Hideki SAKAI, 12th International Symposium on Advanced Vehicle Control, 2014 11
- Detection of Driver’s Short-Term Reducion of Lane-Keeping Ability within Several Seconds, Hideki SAKAI, FISITA2014, 2014 06
- Design for Vehicle Dynamic Behaviour Under Force Control, Hideki SAKAI, FISITA2014, 2014 06
- A Consideration to Yaw Resonance Phenomenon, 2013 05
- Method for recognition of numbers on speed limit signs utilizing an eigen space method based on the KL transform, 12th International conference on Control, Automation, Robotics and Vision(ICARCV 2012), 2012 12 , 12th International conference on Control, Automation, Robotics and Vision(ICARCV 2012)
- Recognition of numbers on speed limit signs utilizing an eigen space method based on the KL transform, 2012 09
- Development of active safety system utilizing steady weaving (first repot), 2012 05
- Development of active safety system utilizing steady weaving (second repot), 2012 05
- Development of active safety system utilizing steady weaving (third repot), 2012 05
- The Development of Tire Lateral Force Model Considering the Dependence of Surface Temperature of Tire, 2012
- Enhancement of vehicle dynamic behavior based on visul and motion sensitivity (First repot), 2012
- Damping control to enhance transient cornering feel, 2011 10
- Consideration for vehicle transient behavior under forced control, 2011 05
- Traffic simulator for evaluating advanced driver assistance system, 2010 01
- Development of advanced safety system & traffic realtime estimation tool(ASSTREET) to assure computation trustworthiness(first report), 2009 05
- Development of advanced safety system & traffic realtime estimation tool(ASSTREET) to assure computation trustworthiness(second report), 2009 05
- Vehicle Transient Response Based on Human Sensitivity, AVEC '08 Proceedings, 2008 08
- Motion drive method for a high-fidelity driving simulator and motion sickness valuation, 2008 05
- Vehicle transient response based on human sensitivity, 2007 10
- Improvement of Vehicle Dynamics Based on Human Sensitivity (Fist Report) - Development of Human Sensitivity Evaluation System, 2007 03
- Enhancement of Vehicle Dynamic Behavior Based on Visual and Motion Sensitivity (Third Repot) -A Study of Pitch-, 2006 09
- Enhancement of vehicle dynamic behavior based on visual and motion sensitivity (third report), 2006 09
- Enhancement of Vehicle Dynamic Behavior Based on Visual and Motion Sensitivity (Second Report) - A Study of Roll Feeling ?, 2006 08
- Extension of Effective Cornering Stiffness by Complex Cornering Stiffness, 2006 06
- Enhancement of Vehicle Dynamic Behavior on Visual and Motion Sensitivity (Second Report), 2006 05
- The Influence of Roll Characteristics on Vehicle Dynamic Behavior, 2005 10
- The analysis of the vehicle stability after releasing the accelerator in a turn, 2004 10

- nhancement of Vehicle Dynamic Behavior Based on Visual and Motion Sensitivity (First Report) - Development of Human Sensitivity Evaluation System ?, 2006 08
- Enhancement of vehicle dynamic behavior based on visual and motion sensitivity( First report) - Development of human sensitivity evaluation system -, 2006 05
- Analysis of Vehicle Stability after Releasing the Accelerator in a Turn, 2005 03 , 10.4271/2005-01-0411
- The analysis of the vehicle stability after releasing the accelerator in a turn, 2004 10
- The Modeling of Tire Overturning Moment Charactristics and Its Influence on Vehicle Behavior, 2004

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