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A dual piston Variable Compression Ratio (VCR) engine has been newly developed. This compact VCR system uses the inertia force and hydraulic pressure accompanying the reciprocating motion of the piston to raise and lower the outer piston and switches the compression ratio in two stages. For the torque characteristic enhancement and the knocking prevention when the compression ratio is being switched, it is necessary to carry out engine controls based on accurate compression ratio judgment. In order to accurately judge compression ratio switching timing, a control system employing the Hidden Markov Model (HMM) was used to analyze vibration generated during the compression ratio switching. Also, in order to realize smooth torque characteristics, an ignition timing control system that separately controls each cylinder and simultaneously performs knocking control was constructed.

When a vehicle is in motion, noise is generated in the cabin that is composed of noise in multiple narrow-frequency bands and caused by input from the road surface. This type of noise is termed low-frequency-band road noise, and its reduction is sought in order to increase occupant comfort. The research discussed in this paper used feedback control technology as the basis for the development of an active noise control technology able to simultaneously reduce noise in multiple narrow-frequency bands. Methods of connecting multiple single-frequency adaptive notch filters, a type of adaptive filter, were investigated. Based on the results, a method of connecting multiple filters that would mitigate mutual interference caused by different controller transmission characteristics was proposed.

The technology to estimate engine load using the amplitude of crankshaft angular velocity variation during a cycle, which is referred to as “Δω (delta omega)”, in a four-stroke single-cylinder gasoline engine has been established in our former studies. This study was aimed to apply this technology to the spark advance control system for small motorcycles. The cyclic variation of the Δω signal, which affects engine load detection accuracy, was a crucial issue when developing the system. To solve this issue, filtering functions that can cope with various running conditions were incorporated into the computation process that estimates engine loads from Δω signals. In addition, the system made it possible to classify engine load into two levels without a throttle sensor currently used. We have thus successfully developed the new spark advance system that is controlled in accordance with the engine speed and load.

The mounting of lithium-ion batteries (LIB) in hybrid electric vehicles (HEV) calls for the configuration of highly robust control systems. When mounting LIBs in the vehicle, it is important to accurately ascertain and precisely control the state of the battery. In order to achieve high durability, it is important to configure highly reliable systems capable of dependably preventing overcharging as well as to have control technology based on software that can contribute to extended battery life. The system configuration applies an overcharge prevention system that uses voltage detection with an emphasis on reliability. Furthermore, a method for varying the range of state of charge (SOC) control in the vehicle according to the battery state is implemented to assure durability. In order to achieve this, battery-state detection technology was developed for the purpose of correctly detecting and judging the battery state.

Vehicles are required durability in various environments all over the world. Especially water resistance on flooded roads is one of the important issues. To solve this kind of problem, a CFD technology was established in order to predict the water resistance performance of the vehicle at the early development stage. By comparison with vehicle tests on flooded roads, it is clarified the following key factors are required for accurate prediction; the vehicle velocity change, the vehicle height change and the air intake flow rate. Moreover, these three key factors should be appropriately determined from vehicle and engine specification to predict water intrusion for flooded roads at the early stage of development. In this paper, a methodology which determines appropriate analysis conditions mentioned above for flooding simulation from vehicle and engine specification is described. The methodology enables us to determine whether the vehicle provides sufficient waterproofness.

A hybrid simulation model in the transient bench was developed to realize the characteristics of the transient behavior and the fuel economy equivalent to that of a real vehicle. The motors and the batteries that were main components of the hybrid vehicle system were simulated as constructive modules, the functions of which have the integrated control and the input/output (I/O) function with real components. This model enabled us to accommodate a variety of auxiliary (AUX) I/O flexibly. The accuracy of the model was verified by the transient characteristics of the engine and the fuel economy result through correlation with a mass-produced vehicle. Furthermore, the flexibility of the model to a variety of AUX I/O was examined from the simulation test of the vehicle equipped with the waste heat recovery (WHR) system.

Recently, emission regulations have been strict in many countries, and it is very difficult technical issue to reduce emissions of diesel cars. In order to reduce the emissions, various combustion technologies such as Massive EGR, PCCI, Rich combustion, etc. have been researched. The combustion technologies require precise control of the states of in-cylinder gas (air mass flow, EGR rate etc.). However, a conventional controller such as PID controller could not provide sufficient control accuracy of the states of in-cylinder gas because the air-pass system controlled by an EGR valve, a throttle valve, a variable nozzle turbo, etc. is a multi-input, multi-output (MIMO) coupled system. Model predictive control (MPC) is well known as the advanced MIMO control method for industrial process. Generally, the sampling period of industrial process is rather long so there is enough time to carry out the optimization calculation for MPC.

Today’s progress in electronic technologies is advancing the process of making vehicles more intelligent, and this is making driving safer and more comfortable. In recent years, numerous vehicles equipped with high-level Advance Driving Assist System (ADAS) have been put on the market. High-level ADAS can detect impending lane deviation, and control the vehicle so that the driver does not deviate from the lane. Lane departure prevention systems are able to detect imminent departure from the road, allowing the driver to apply control to prevent lane departure. These systems possess enormous potential to reduce the number of accidents resulting from road departure, but their effectiveness is highly reliant on their level of acceptance by drivers.

A new brake system, able to make efficient use of regenerative braking while maintaining excellent brake feel, has been developed to increase the fuel economy of hybrid vehicles. A hydraulic servo was used as a base to enable mechanical operation of the service brakes; solenoid valves and brake fluid pressure sensors were added to this base to make it possible to control brake line pressure as demanded. The use of a stroke simulator in the hydraulic servo prevents brake feel from being affected by the control of the brake pressure. In addition, high-accuracy brake pressure control that functions cooperatively with the regenerative brakes is enabled, resulting in stable braking effectiveness.

A continuously variable valve lift gasoline engine can improve fuel consumption by reducing pumping loss and increase maximum torque by optimizing valve lift and cam phase according to engine speed. In this research, a new control system to simultaneously ensure good driveability and low emissions was developed for this low fuel consumption, high power engine. New suction air management through a master-slave control made it possible to achieve low fuel consumption and good driveability. To regulate the idle speed, a new controller featuring a two-degree-of-freedom sliding-mode algorithm with cooperative control was designed. This controller can improve the stability of idle speed and achieve the idle operation with a lower engine speed. To reduce emissions during cold start condition, an ignition timing control was developed that combine I-P control with a sliding mode control algorithm.

In recent years, the increased use of electric power steering in vehicles has increased the importance of issues such as making systems more compact and lightweight, and dealing with increased development man-hours. To increase development efficiency, the use of a “Hardware in the loop simulator” (HILS) is being tested to shift from the previous development method that relied on a driver's subjective evaluation in an actual vehicle test to bench-test development. Using HILS enables tasks such as specification studies, performance forecasts, issue identification and countermeasure proposals to be performed at an early stage of development even when there is no prototype vehicle. This report describes a case study of using HILS to solve the issues of reducing the load by adjusting the geometric specifications around the kingpin and eliminating the tradeoff by adding a new EPS control algorithm in order to make the electric power steering (EPS) more compact and lightweight.

In conventional electronically controlled fuel injection systems, when the battery is inadequately charged, the small amount of electric power generated from the alternator by the kick starter operation is consumed by all electrical loads including the battery. This causes a voltage drop, hence the fuel injection system does not function due to a power shortage. To eliminate the power shortage, an installed relay circuit opens all electric loads other than the fuel injection system. This allows the fuel injection system to use all the electric power generated by the kick starter operation aided through using an additionally incorporated condenser. This type of electric power control system has been incorporated into the ECU. Thus, the control system has been realized that permits starting of an engine by using the kick-starter even when the battery is completely discharged.

The Vehicle Stability Assist (VSA) system can generate sufficient forces to rapidly change the vehicle's motion. We can use this capability to effectively control the vehicle's behavior, but we must pay careful attention to ensure its reliability. The VSA system should be precisely tuned for each vehicle's characteristics in order to satisfactorily control performance without any unnecessary intervention or any excessive warnings. Usually extensive field tests are necessary to precisely tune the VSA system. This paper presents a practical method to tune the VSA system with Hardware-In-the-Loop (HIL) simulations in the final stage of its development. Due to the application of this procedure, both high control capabilities and reliability of the VSA system can be achieved.

Honda has developed a new 5 speed all clutch to clutch automatic transmission (AT) as the next generation AT for passenger cars and succeeded in shortening the overall length, increasing the efficiency and improving the shift feeling by enhancing the intelligence of the system. This paper describes the mechanical structure, the new direct control system and the newest shift control method of the AT system.

The reduction of fuel consumption is of great importance to automobile manufacturers. As a prospective means to achieve fuel economy, lean burn is being investigated at various research organizations and automobile manufacturers and a number of studies on lean-burn technology have been reported to this date. This paper describes the development of a four-valve lean-burn engine; especially the improvement of the combustion, the development of an engine management system, and the achievement of vehicle test results. Major themes discussed in this paper are (1) the improvement of brake-specific fuel consumption under partial load conditions and the achievement of high output power by adopting an optimized swirl ratio and a variable-swirl system with a specially designed variable valve timing and lift mechanism, (2) the development of an air-fuel ratio control system, (3) the improvement of fuel economy as a vehicle and (4) an approach to satisfy the NOx emission standard.

To comply with the environmental demands for CO2 reduction without compromising driving performance, a new 1.0 liter I3 turbocharged gasoline direct injection engine has been developed. This engine is the smallest product in the new Honda VTEC TURBO engine series (1), and it is intended to be used in small to medium-sized passenger car category vehicles, enhancing both fuel economy through downsizing, state-of-the-art friction reduction technologies such as electrically controlled variable displacement oil pump and timing belt in oil system, and also driving performance through turbocharging with an electrically controlled waste gate. This developed engine has many features in common with other VTEC TURBO engines such as the 1.5 liter I4 turbocharged engine (2) (3), which has been introduced already into the market.

A multi-body simulation coupled with a tire model enables the prediction of forces generated on a vehicle when driven over a rough road profile. As the durability of a vehicle depends on these generated forces, the accuracy of the predicted forces is a crucial factor in assessing durability. A new test setup has been used to evaluate the accuracy of the simulation. Due to good reproducibility, the results from physical testing and simulation can be compared in the time domain. This time domain comparison makes it possible to detect any problems associated with the simulation which need to be improved. This new evaluation method is very suitable to full vehicle simulations involving rough road profiles. It was also confirmed that the suspension model with tire model evaluated in this project had an adequate capability for curb strike simulation by a full vehicle.

Lane departure prevention systems are able to detect imminent departure from the road, allowing the driver to apply control to prevent lane departure. These systems possess enormous potential to reduce the number of accidents resulting from road departure, but their effectiveness is highly reliant on their level of acceptance by drivers. The effectiveness of the systems will depend on when they are providing driving assistance, what level of laxness in terms of maintaining contact with the steering wheel is allowed on the part of the driver, and what level of assistance the system provides. This paper will discuss research on the minimum necessary contact and contact strength with the steering wheel on the part of the driver when a lane departure prevention system is in operation.

A multi-use road simulator for reproducing various road loads on motorcycles and buggies has been developed on a test bench by using computer-controlled hydraulic actuators. The device is controlled by a low-priced personal computer and an interface system with custom software. An unique feature is the capability to simulate loads related to such phenomena as the bottoming of suspension and the movement of a telescopic type front fork on the road.

Using stabilizing yaw-moment diagrams, the authors analyzed three methods of active chassis control for their effect and effective ranges during cornering maneuvers. The following results were obtained: controlling the transverse distribution of driving and braking forces cancels the changes in a vehicle's dynamic characteristics caused by acceleration and deceleration. Controlling the distribution of roll stiffness is only effective in ranges with high lateral acceleration, and the effect varies depending on the longitudinal weight distribution. Controlling the rear wheel steering angle is most effective in a range with a small side slip angle, but this effect decreases with an increase in the angle, especially during deceleration.