Toshihiro Hiraoka

Automatic path-tracking controller of a four-wheel steering vehicle

The present paper proposes an automatic path-tracking controller of a four-wheel steering (4WS) vehicle based on the sliding mode control theory. The controller has an advantage in that the front- and rear-wheel steering can be decoupled at the front and rear control points, which are defined as centres of percussion with respect to the rear and front wheels, respectively. Numerical simulations using a 27-degree-of-freedom vehicle model demonstrated the following characteristics: (1) the automatic 4WS controller has a more stable and more precise path-tracking capability than the 2WS controller, and (2) the automatic 4WS controller has robust stability against system uncertainties such as cornering power perturbation, path radius fluctuation, and cross-wind disturbance.

Cooperative steering system based on vehicle sideslip angle estimation from side acceleration data at percussion centers

This paper considers how a manual steering scheme can be combined with automatic steering for a cooperative steering system which yields better stability, together with path following capability. A new version of the combination is proposed based on a course error differential equation at a percussion center with respect to rear-wheels. The automatic steering includes the feedback of vehicle sideslip angle which is difficult to measure by an ordinary device. An adaptive estimation scheme is proposed to feedback the sideslip angle. Driving simulator experiments demonstrate good estimates and good performance of the cooperative steering system.

Fundamental research about the effectiveness of a safe driving support system with information provision

Recently, safe driving support systems such as AHS-i have been proposed. In this paper, we investigate the relationship between the reliability of information provided from a safety system and the drivers unsafe action, and then quantitatively analyze the reliability level required for the system to reduce traffic accidents.

Development of drowsy driving accident prediction by heart rate variability analysis

Drowsy driving accidents can be prevented if it can be predicted in advance. The present work aims to develop a new method for predicting a drowsy driving accident based on the fact that the autonomic nervous function affects heart rate variability (HRV), which is the fluctuation of the RR interval (RRI) obtained from an electrocardiogram (ECG). The proposed method uses HRV features derived through HRV analysis as input variables of multivariate statistical process control (MSPC), which is a well-known anomaly detection method in process control. Driving simulator experiments demonstrated that driver drowsiness was successfully predicted seven out of eight cases before drowsy driving accidents occur.

Proposal of non-dimensional parameter indices to evaluate safe driving behavior

Our previous study proposed Deceleration for Collision Avoidance (DCA) as an new index for use when evaluating collision risk against forward obstacles. The present manuscript proposes four non-dimensional parameter indices which are based mainly on the DCA, in order to provide quantitative assessment of safe driving behavior. Numerical simulations are performed to verify validity of the proposed indices.

Making Systems Inconvenient to Stimulate Motivation of Competent Users

This paper evaluates user motivation when they use two applications for unlocking mobile phones. One is a convenient application that adapts to users and the other is an inconvenient application that does not adapt to users but only gives feedback to help them adapt to the system. Our hypothesis is that inconvenience gives users space to develop their skills for using a system. This space props up the motivation of users while adaptive systems often reduce the space for such skill improvements by discouraging motivation. The experimental results show that the competence of users correlates with motivation when they use the inconvenient system, there is no correlation when using the convenient system. The results imply that inconvenience, which provides users space for skill improvement, stimulates the motivation of users under the condition of user competence.

Fundamental research on driver’s haptic characteristics concerning steering reactive torque

Steering reactive torque presentation is one of driving support systems for a steer-by-wire (SBW) vehicle, and it would inform the road surface condition and the working state of the system. However, driverpsilas sensory characteristics for the steering reactive torque are not known very well, and therefore, the steering reactive torque gain is decided by trial and error. The present paper performs experiments using a haptic interface which can provide arbitrary steering reactive torque to subjects, and it would elucidate the haptic characteristics for the change of the steering reactive torque in the case of a constant steering and a periodic steering.

Fuzzy Logic as Interfacing Media for Contraint Propagation Based on Theories of Chu Space and Information Flow

In this paper, we will introduce a novel perspective on Fuzzy Logic by referring to the theories of Chu Space and Information Flow, i.e., Channel Theory, which results in a deep insight on the interaction and coordination of agents with environments. First, a constraint-oriented interpretation of fuzzy set is introduced yielding the notion of Constraint-Interval Fuzzy Set (CoIFS). Then the above theories are introduced, which elucidate the basic structures of fuzzy inference as constraint propagation yielding the spaces of Coordination and Interaction. Also, the structure of Information Transmission Channel of constraint propagation is clarified together with its relevance with the results by the theory of Chu Space. All the results can be used to elucidate the basic structure of “interfacing (interfacing media)” between agents and environments.

Improvement of Evaluation Indices for Rear-End Collision Risk

There are various kinds of indices to evaluate collision risk against forward obstacles, which are used to determine the timing of collision warning provision in forward obstacle collision warning systems (FCWSs) and advanced emergency braking systems. A previous study proposed a deceleration for collision avoidance (DCA) method, which can evaluate a collision risk more precisely than other conventional indices. However, the calculation process of DCA assumed that a following vehicle (FV) performs a uniform motion within a drivers constant reaction time. The assumption causes underestimation of collision risk when the FV accelerates and overestimation when it decelerates. Consequently, this paper shows a detailed calculation process of an improved DCA based on an expanded assumption that the FV maintains a uniformly accelerated motion within the reaction time. Moreover, stimulus-response experiments were conducted to measure the drivers reaction time when he/she adjusts the brake pedal depression. Numerical simulations, where DCA is used for the FCWS, were performed to show that the improved DCA (with a new setting for the driver reaction time) describes the collision risk more properly compared to the conventional DCA.

A Scheme for Representing Beneficial Inconvenience

This paper proposes a representation scheme of human-machine interaction that provides users with beneficial inconvenience. The scheme consists of three layers. The top layer represents user-dependent subjective matters, and the middle layer describes inconvenience as an objective phenomenon that creates opportunities to get objective benefits. The bottom contains a task-achievement model whose basic structure is a triangle relation among user, object, and system, based on Vygotsky’s insight into human activities. This paper demonstrates the performance of our scheme by representing typical situations for obtaining beneficial inconveniences in a uniform construction. This scheme can also be used as a testing ground of fuben-eki designs. Fuben-eki stands for the benefits of inconvenience, and a fuben-eki design means a design that appreciates the concept of fuben-eki.