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We have developed a system for automatic deceleration upon entering curves to prevent collisions on tight curves on high-ways. The navigation system is used to determine safe speed negotiating the curve, defined as a speed that will keep lateral acceleration within a settled value. The navigation system sends the curve radius to a controller, which calculates the safe speed for the curve. The controller then sends the speed command to the ACC system, which adjusts the vehicle speed. One of the important features in this system is the estimation of the vehicle position, in terms of its distance from the curve entrance. Navigation systems have a certain amount of dispersion in positional accuracy. A front camera is used in our system to decrease this dispersion. This camera detects lane markers (white lines, raised pavement markers, etc.) using our line recognition technologies1).

Balancing between dependability and cost-effectiveness is essential to promote X-by-Wire systems in the next decade. To achieve this goal, we have so far proposed a network centric architecture based on a concept of autonomous decentralized systems, where if one node fails, the remaining normal nodes autonomously execute a backup control to maintain the system's functionality, as well as a membership middleware indispensable to this architecture to ensure the consistency of the node status information among all nodes. In this work, we implemented membership middleware on a hardware and software platform equivalent to one assumed to be used in actual X-by-Wire systems. This paper describes the implementation details and performance evaluation result, and shows that membership middleware and a real-time critical application can coexist within one microcontroller.

The increasing number of controllable parameters in modern engine systems has led to increasingly complicated and enlarged engine control software. This in turn has created dramatic increases in software development time and cost. Model-based control design seems to be an effective way to reduce development time and costs and also to enable engineers to understand the complex relationship between the many controllable parameters and engine performance. In the present study, we have developed model-based methodologies for the engine calibration process, employing engine cycle simulation and regression analysis. The reliability of the proposed method was investigated by validating the regression model predictions with measured data.

In this paper, a newly developed three-dimensional (3D) bird's-eye view map drawing technique for car navigation systems is described. Conventional navigation systems give pseudo-perspective views which can not express ruggedness like hills and valleys. Our newly developed navigation system can display undulation of the land from viewpoints above and behind the current position, so that ups and downs of roads along with the driver's destination can be seen easily. The 3D-road map is not only effective during navigation but also during route planning, because it assists in searching for fine views before travel. In order to achieve the 3D-map view, we developed graphics software libraries, which work on a 32-bit RISC processor and on a low-cost graphics accelerator LSI with texture mapping capability. The graphics software libraries are constructed with three stages, the perspective projection stage, visible-surface determination stage, and rendering stage.

This paper proposes a new development method for highly reliable real-time embedded control systems using a CPU model-based hardware/software co-simulation. We take an approach that allows the full simulation of the virtual mechanical control system including CPU and object code level software. In this paper, Renesas SH-2A microcontroller model was developed on CoMET™ platform from VaST Systems Technology. A ETC (Electronic Throttle Control) system and engine control system were chosen to prove this concept. The ETB (Electronic Throttle Body) model on Saber® simulator from Synopsys® or engine model on MATLAB®/Simulink® simulator from MathWorks can be simulated with the SH-2A model. To help the system design, debug and evaluation, we developed an integrated behavior analyzer, which can display CPU behavior graphically during the simulation without affecting the simulation result, such as task level CPU load, interrupt statistics, software variable transition chart, and so on.

Every fuel injection system for DI gasoline engines has a DC-DC converter to provide high, stabile voltage for opening the injector valve more quickly. A current control circuit for holding the valve open is also needed, as well as a large-capacity capacitor for pilot injection. Since these components occupy considerable space, an injector drive unit separate from the ECU must be used. Thus, there has been a need for a fuel injection system that can inject a small volume of fuel without requiring high voltage. To meet that need, we have developed a dual coil injector and an opening coil current control system. An investigation was also made of all the factors related to the dynamic range of the injector, including static flow rate, fuel pressure, battery voltage and harness resistance. Both efforts have led to the adoption of a battery voltage-driven fuel injector.

This paper presents the “Virtual Failure Mode and Effects Analysis (vFMEA)” system, which is a high-fidelity electrical-failure-simulation platform, and applies it to the software verification of an electric power steering (EPS) system. The vFMEA system enables engineers to dynamically inject a drift fault into a circuit model of the electronic control unit (ECU) of an EPS system, to analyze system-level failure effects, and to verify software-implemented safety mechanisms, which consequently reduces both cost and time of development. The vFMEA system can verify test cases that cannot be verified using an actual ECU and can improve test coverage as well. It consists of a cycle-accurate microcontroller model with mass-production software implemented in binary format, analog and digital circuit models, mechanical models, and a state-triggered fault-injection mechanism.

The problem of high fatal accident rates due to drunk driving persists, and must be reduced. This paper reports on a prototype system mounted on a car mock-up and a prototype portable system that enables the checking of the drivers’ sobriety using a breath-alcohol sensor. The sensor unit consists of a water-vapor-sensor and three semiconductor gas sensors for ethanol, acetaldehyde, and hydrogen. One of the systems’ features is that they can detect water vapor from human-exhaled breath to prevent false detection with fake gases. Each gas concentration was calculated by applying an algorithm based on a differential evolution method. To quickly detect the water vapor in exhaled breath, we applied an AC voltage between the two electrodes of the breath-water-vapor sensor and used our alcohol-detection algorithm. The ethanol level was automatically calculated from the three gas sensors as soon as the water vapor was detected.

In recent years, improvement of in-use fuel economy is required with tightening of exhaust emission regulation. We assume that one of the most effective solutions is ACC (Adaptive Cruise Control), which can control a powertrain accurately more than a driver. We have been developing a fuel saving ADAS (Advanced Driver Assistance System) application named “Sailing-ACC”. Sailing-ACC system uses sailing stop technology which stops engine fuel injection, and disengages a clutch coupling a transmission when a vehicle does not need acceleration torque. This system has a potential to greatly improve fuel efficiency. In this paper, we present a predictive powertrain state switching algorithm using external information (route information, preceding vehicle information). This algorithm calculates appropriate switching timing between a sailing stop mode and an acceleration mode to generate a “pulse-and-glide” pattern.

In-vehicle networks are generally used for computerized control and connecting information technology devices in cars. However, increasing connectivity also increases security risks. “Spoofing attacks”, in which an adversary infiltrates the controller area network (CAN) with malicious data and makes the car behave abnormally, have been reported. Therefore, countermeasures against this type of attack are needed. Modifying legacy electronic control units (ECUs) will affect development costs and reliability because in-vehicle networks have already been developed for most vehicles. Current countermeasures, such as authentication, require modification of legacy ECUs. On the other hand, anomaly detection methods may result in misdetection due to the difficulty in setting an appropriate threshold. Evaluating a reception cycle of data can be used to simply detect spoofing attacks. However, this may result in false detection due to fluctuation in the data reception cycle in the CAN.

An automotive powertrain total control system using estimated output shaft torque has been investigated in order to enhance drivability and improve fuel economy. The system provides efficient control for both the engine and transmission which leads to an enhancement in drivability by reducing shocks during gear shifts. This paper describes a new smooth gear shift control method using the total control system. By use of the estimated output shaft torque, it is possible to detect accurately the fluctuation condition and the start time of the inertia phase, which are important factors affecting shock occurrence. Torque feedback, got from estimated torque, was applied to the control of engine output shaft torque during shifts. The optimum hydraulic pressure, also got from estimated torque, was applied to the clutch of the transmission during shifts.

To detect difficult-to-find defects in automotive control systems, we have proposed a modeling method with a program slicing technique. In this method, a verifier adjusts the boundaries of source code to be extracted on a variable dependence graph, in a kind of data flow. We have developed software tools for this method and achieved a 35% decrease in total verification time on model checking. This paper provides some consideration on effective cases of the method from verification practices. There are two types of malfunction causes: one is the timing of processes (race conditions), and the other is complex logics. Each type requires different elements in external environment models. Furthermore, we propose regression verification based on the modeling method above, to further reduce verification time on model checking. The paper outlines tool extensions needed to realize regression verification.

A totally integrated vehicle electronic control system is described, which optimizes vehicle performance through use of electronics. The system implements efficient coordination of functions of the engine, drive-train, brakes, steering, and suspension control subsystems to give a smoother ride, better handling and greater safety. The principles of the system are based on control and stability augmentation strategies. Each subsystem has two observers which control the force of the actuators according to the vehicle dynamics. The system features a driver support system which allows the average driver to employ the full performance potential of the vehicle in exceptional situations, and an artificial response control system to ensure optimum response and comfort. Application of the system allows the driver to experience a new level of performance and a marked improvement in handling quality and ride comfort.

This paper describes a state adaptive control method for vehicle suspensions proposed by Hitachi, Ltd. The objective of the control is to improve riding comfort and driving stability in reaction to road iregularities, exterior wind forces, and changes in vehicle loads as well as in reaction to inertial changes during cornering, breaking, and accelerating. The objective is attained by making considerable use of the relative displacement data between the body and the suspension. The state adaptive control system includes four shock absorbers whose damping forces can be tuned in three stages, four height sensors which measure the relative displacement, a vehicle speed sensor, and a microcomputer which decides the optimal damper stage. The validity of the proposed control method is shown through computer simulations and actual driving experiments. Vertical acceleration is reduced by about 55 % by switching from the soft damper to the hard damper in a computer simulation.

The concept of a “controller grid”, which makes effective use of computational resources distributed on a network while guaranteeing real-time operation, is proposed and applied to realize highly advanced control. It facilitates the total optimization of a plant control and achieves the high efficiency that is not acquired by individual plant optimization. To realize this concept, migration of a control task customized to be executed on one particular microcontroller to another microcontroller is necessary while strictly observing the required response time. Two techniques to meet this requirement are proposed: “task migration” for a control system and “real-time guaranteed scheduling of task migration and execution”. The effectiveness of the controller grid is assessed by applying it in experiments with electronic-throttle-body (ETB) advanced control.

Gasoline engine control continues to become more sophisticated and so the amount of software has reached 10 to 20 times that of early control systems. By changing the embedded microcomputer from 8bit CISC (Complex Instruction Set Computer) to 32bit RISC (Reduced Instruction Set Computer), processing performance has been improved 100 times. This paper evaluates quantitative performance of the RISC CPU having a FPU (Floating Point Processing Unit) and describes an example application to adaptive control.

A virtual power window control system was built in order to look into and demonstrate applications of microcontroller models. A virtual ECU simulated microcontroller hardware operations. The microcontroller program, which was written in binary digital codes, was executed step-by-step as the virtual ECU simulation went on. Thus, production-ready codes of ECUs are of primary interest in this research. The mechanical system of the power window, the DC motor to lift the window glass, the H-bridge MOSFET drivers, and the current sensing circuit to detect window locking are also modeled. This means that the hardware system of the control system was precisely modeled in terms of mechanical and circuit components. By integrating these models into continuous and discrete co-simulation, the power window control system was analyzed in detail from the microscopic command execution of the microcontroller to the macroscopic motion of the window mechanism altogether.

We have developed a cooperative simulation environment for multiple electronic control units (ECUs) including a parallel executions mechanism to improve the test efficiency of a system, which was designed with multiple ECUs for autonomous driving. And we have applied it to a power window system for multiple ECUs with a controller area network (CAN). The power window model consists of an electronic-mechanical model and a CPU model. Each simulator with a different executions speed operates in parallel using a synchronization mechanism that exchanges data outputted from each simulator at a constant cycle. A virtual ECU simulated microcontroller hardware operations and executed its control program step-by-step in binary code to test software for the product version. As co-simulation technology, a mechanism that synchronously executes heterogeneous simulators and a model of an in-vehicle communication CAN connecting each ECU were developed.

We have developed a full virtual engine system prototyping platform with 4-cylinder engine plant model, SH-2A CPU hardware model, and object code level software including OSEK OS. The virtual engine system prototyping platform can run simulation of an engine control system and digital knock detection system including 64-pt FFT computations that provide required high-resolution DSP capability for detection and control. To help the system design, debugging, and evaluation, the virtual system prototyping consists of behavior analyzer which can provide the visualization of useful CPU internal information for control algorithm tuning, RTOS optimization, and CPU architecture development. Thus the co-simulation enables time and cost saving at validation stage as validation can be performed at the design stage before production of actual components.

“Virtual Failure Mode and Effects Analysis” (vFMEA), a novel safety-verification method of control software for automotive electronic systems, was proposed to save prototyping cost at verification stage. The proposed vFMEA is system-level FMEA method, which uses virtualized electronic control units (ECUs) consisting of microcontroller models on a microcontroller simulator and a transistor-level circuit models on a circuit simulator. By using the structure, the control software in binary code formats can be verified when a circuit-level fault occurs in the ECU hardware. As an illustrative example, vFMEA was applied to an engine ECU. As a result of short-circuit fault into a driver IC, engine revolution and engine speed decreased. However, the engine continued to operate normally when an open-circuit fault occurred in a capacitor connected in parallel. Effects of the hardware faults in ECU on a vehicle are demonstrated; thereby software verification can be performed using vFMEA system.