Search

The ringing and the resulting asymmetry in the propagation delay are the main causes of bandwidth degradation and communication errors in a controller area network (CAN) with flexible data rate. Therefore, in this paper, the mechanism of ringing is analyzed, and the ringing suppression circuit is proposed based on the analysis. The proposed circuit includes an impedance matching resistor and a forward-biased diode for terminating the repetition of reflections and limiting the magnitude of the ringing. These components are temporarily connected by operating a switch that is controlled by the TxD signal of a CAN controller so that the ringing suppression circuit only engages when necessary and at the correct time. The performance of the ringing suppression circuit is verified by experiments. The experimental results show that the proposed circuit keeps the ringing adequately suppressed and the good symmetry in the propagation delay across the physical bus is possessed.

Signal distortion, called ringing, in a controller area network with flexible data rate (CAN-FD) causes asymmetry in propagation delay throughout a network, which is dependent on its physical bus design and becomes a critical issue in limiting the data rate. Thus, in this paper, the bus structure of a CAN-FD is investigated and a transfer function of ringing is modeled by considering the physical bus configuration and features of a controller area network transceiver. The effects of the main parameters of the physical bus, such as the stub line length and number of stub lines connected to a joint connector, are then quantitatively analyzed using the presented model. When a practical bus structure is considered, additional signal distortion owing to a neighboring connector in a physical bus is modeled and analyzed. These analytical results are confirmed experimentally. Their comparison shows that the presented model-based analysis can closely approximate the size and time response of ringing and the extent of bit time distortion. The presented model-based analysis facilitates reliable communication performance by estimating the ringing and resulting asymmetry of the propagation delay for a given physical bus design and, if necessary, adjusting the design.

Hybrid electric vehicles (HEVs) provide a promising alternative to conventional engine-powered vehicles, with less emission and better fuel economy. This study proposes a hierarchical control for a power-split HEV over a driving cycle, featuring pre-trip optimisation and en-route speed adaption. Constraints including vehicle powertrain boundaries, road gradients, and speed limits, are taken into consideration. In the first stage, the HEV operating conditions, including the optimal vehicle SOC, speed profiles, and total driving time, are generated for the entire trip before departure. Based on the pre-trip results, the second stage adapts the vehicle speed for a short horizon when driving, while taking the safety spacing to the preceding vehicle into consideration, which acts as an indicator of actual traffic conditions and guarantees safe driving. Both optimisations are conducted under the distance domain for realising localisation in the optimal speed profile due to frequent changes in traffic conditions. An estimation of distribution algorithm is used to run the simulation so that the feasibility, robustness, and effectiveness of the proposed hierarchical control can be demonstrated.

This paper proposes a distance-based two-stage energy management strategy for power-split plug-in hybrid electric vehicles (PHEVs). One stage is for long-term optimization and the other is for short-term adaptation to actual traffic conditions. Energy consumption in PHEVs depends on the characteristics of the drivetrain as well as the operating conditions such as power demands and their split. Thus, prior to departure, the operating conditions for a whole trip are optimized for the drivetrain characteristics and trip information, which generates optimal speed and state-of-charge profiles. While driving, the operating conditions are adapted to current traffic conditions for a short horizon on the basis of long-term optimization results. In consideration of the changeability of traffic conditions, the proposed energy management strategy is performed in a distance domain, which localizes the effects of changes in traffic conditions on the long-term optimization results. Therefore, this distance-based two-stage strategy improves the balance between the optimality and the real-time computing time, which is suitable for online management. A model for the propulsion system in a PHEV and the energy management strategy were formulated in a distance domain. An estimation of distribution algorithm was used for long-term optimization and local adaptation.

This paper proposes a distance-based two-stage ecological (eco-) driving scheme by using estimation of distribution algorithms (EDA) and model-based prediction of traffic conditions. Before departure, the optimal speed profile for an entire route is generated by an EDA in combination with speedup approaches for a faster computing time, which can optimize the complex cost function of ecodriving without simplification within a reasonably short computing time. This optimization is performed in a distance domain for localizing changes in the optimal speed profile due to traffic conditions while driving. After departure, by taking the optimal speed profile and actual traffic conditions into consideration, the speed profile for a short term—to only the next location—is adapted. In order to reliably react to actual traffic conditions, additional points are interpolated into the long-term distance step and fine control of speeds at the additional points is established, which is based on a predictive model for estimating the spacing to the preceding vehicle. The proposed ecodriving system is evaluated in two types of route conditions, and its results are compared with the optimization result by the quadratic programming method. This comparison shows that an EDA can generate a speed profile with better optimization results in terms of fuel efficiency and driving time within a shorter computing time.

In proton therapy, for both therapeutic effectiveness and patient safety, it is very important to accurately measure the proton dose distribution, especially the range of the proton beam. For this purpose, recently we proposed a new imaging method named gamma electron vertex imaging (GEVI), in which the prompt gammas emitting from the nuclear reactions of the proton beam in the patient are converted to electrons, and then the converted electrons are tracked to determine the vertices of the prompt gammas, thereby producing a 2D image of the vertices. In the present study, we developed a prototype GEVI system, including dedicated signal processing and data acquisition systems, which consists of a beryllium plate (= electron converter) to convert the prompt gammas to electrons, two double-sided silicon strip detectors (= hodoscopes) to determine the trajectories of those converted electrons, and a plastic scintillation detector (= calorimeter) to measure their kinetic energies. The system uses triple coincidence logic and multiple energy windows to select only the events from prompt gammas. The detectors of the prototype GEVI system were evaluated for electronic noise level, energy resolution, and time resolution. Finally, the imaging capability of the GEVI system was tested by imaging a 90 Sr beta source, a 60 Co gamma source, and a 45-MeV proton beam in a PMMA phantom. The overall results of the present study generally show that the prototype GEVI system can image the vertices of the prompt gammas produced by the proton nuclear interactions.

This paper proposes a distance-based ecological (eco)-driving scheme with two stages: one for long-term speed optimization and the other for short-term adaptation to actual traffic conditions. Before departure, the speed profile for an entire route is optimized in a distance domain by using characteristics of the drivetrain and road conditions. Then, while driving, the speed at only the next location is controlled to follow the optimal speed profile and adapt it for traffic conditions, which allows for real-time adaptation, maintaining optimal driving in the long term. To localize the change of the optimal speed profile due to traffic conditions, models for fuel rate of a conventional vehicle and vehicle propulsion systems were formulated in a distance domain, and a distance-based optimal speed profile was generated. The proposed eco-driving scheme is optimized by the quadratic programming method, and its validity is tested by simulation.

An automotive junction box distributes electric power to electric systems installed in a vehicle with overcurrent protection. As a larger number of electric systems are installed, the junction box is equipped with more components, functionalities and connections. However, owing to the fuse accessibility, its installation space is so restricted that a downsized design is required for the junction box. The junction box is composed of small signal circuitry for control and monitoring, and large current-carrying circuitry for power distribution which includes many parallel traces. Because of these unique features, widely used techniques for downsizing printed-circuit boards are not applicable. Also, there is no rule for designing large current-carrying parallel traces, and it is difficult to optimize the size of the printed-circuit board for the automotive junction box. This paper presents the design rules for a printed-circuit board when downsizing a junction box. First, the layout strategy for the power distribution components is presented, which is determined by the sum of the squares of the currents flowing through connector pairs. Then, the thermal effects of parallel traces are simulated for different conditions by using thermal analysis software. Based on the results, an analytical estimation of the additional temperature rises due to parallel traces and rules for a thermally effective arrangement of the parallel traces are presented.

A constant fraction discriminator (CFD) is a widely used time-pickoff circuit because it ideally produces no time walk for signals with equal rise times. However, a practical CFD produces some time walk because of the dependency of the response time in an involved comparator on the input signal size. In this paper, a CFD combined with an automatic gain control (AGC) circuit at the input stage is proposed to reduce this dependence. The AGC has four step gains that are inversely proportional to the amplitude of their input signal. Accordingly, the AGC reduces the dynamic range of the signal entering the CFD and consequently reduces the dependency of the response time on the input signal, i.e., time walk. For a short resolving time, this gain setting is performed at one time by amplitude comparison. The proposed CFD is evaluated by experiment for input signals with a rise time of 2 ns and a dynamic range of 40 dB, and the time walk is reduced to 277 ps, a decrease of more than 42%.

The high-speed controller area network protocol supports a linear wiring topology. However, owing to productivity and cost concerns, actual networks in automotive applications may be configured in a star-like topology using joint connectors, with multiple stubs diverging from one point on the main bus; this type of configuration may lead to increased signal reflection and requires careful design of the physical wiring. In this study, the time response in a star-like joint-connector-based controller area network bus topology is analysed, and design guidelines for the physical wiring are presented. The effects of the number of stubs connected to a joint connector on the signal transmission are described and evaluated through experiments. Then, the time response through a joint connector with a diverse number of stubs is estimated, which gives a timing reference for designing the physical wiring in a star-like bus topology. Additionally, the effects of reflection between adjacent joint connectors are analysed together with the distance between joint connectors to ensure that no propagation delay degradation occurs.

This paper presents a standardization method for designing wire harness systems, based on the control types and functional blocks, for use in commercial vehicles. With a rapid increase in the installation of systems with added new features, it is very important to develop a reliable wire harness design in a short time by standardizing wire harness designs and reusing the standard design. Because the function of a system, particularly, for commercial vehicles, varies significantly on the basis of the requirements, regulations, and options, it is not effective to establish one standard design for one system. In addition, a system with the same function may differ in terms of the input conditions and output loads on the basis of the installed vehicle types, and it is not practical to standardize a harness design targeting an entire system. In this study, the wire harness designs of a system were classified into six categories based on the control types of the system: switch driven, control of a switch, control of an electronic control unit, unit driven, control of a unit, and connector operation. Then, a wire harness design of each system was divided into three blocks according to their functions: the control, drive, and monitoring blocks. The standard wire harness designs were made for each functional block of each control type. The advantage of this proposed method is that an effective and practical design can be obtained, which covers the diversities in the same system for different grades of commercial vehicles with a reduction in the number of wire harness supplements.

In this paper, a passive filter is proposed to support a star-like topology in a high-speed controller area network and to extend the length of the stubs. A high-speed controller area network requires a linear wiring topology, while an actual network may be configured as a star-like structure using joint connectors owing to productivity and cost concerns. This joint-connector-based controller area network configuration is likely to suffer from increased signal distortions caused by a larger transient voltage and impedance mismatch. Here, a passive filter for reducing these signal distortions in a joint-connector-based controller area network structure is proposed, which allows a star-like topology with extended stubs. The proposed passive filter is composed of a resistor and bead in series, which is easily inserted in a joint connector. With the proposed filter, the induced transient voltage and settling time in transition to a recessive state were reduced by 37% and 66% respectively. Thus, the proposed filter has the effect of improving the reliability of communication in the same wiring dimension or, equivalently, lengthening the stubs with the same reliability.

The response time of a comparator in a time-pickoff circuit used for time measurement depends on the slope and the overdrive of its input signal. Thus, the generation time of the timing pulse in a time-pickoff circuit is dependent on the amplitude of the input signal, which is the main cause of a timing error. In this study, a time-pickoff method, which employs an automatic gain control (AGC) circuit, is proposed for reducing the timing error called time walk. The AGC circuit in front of the comparator renders the amplitude of the input signals to the comparator to be uniform and the proposed method can be arranged to be relatively independent of the properties of the comparator. The performance of the proposed time-pickoff method was tested and its effectiveness was confirmed through the experiments. It is found that the time walk of the proposed time-pickoff method is less than 227 ps for input signals with a rise time less than 1 ns and a dynamic range of 40 dB.

A plasma display panel (PDP) consists of more than a thousand very thin parallel electrodes on a glass plate. It is quite probable that a PDP has defects such as midway broken electrodes. Therefore, inspecting defects in PDP electrodes is essential for minimizing the manufacturing costs and improving the product quality. In this paper, a new method for inspecting electrodes in a PDP using frequency domain analysis is presented. The transfer function of a PDP was modeled in the frequency domain, which is based on the lumped transmission line models. The effects of the electrode conditions on the frequency response were then analyzed by using the described model, and experiments were conducted with specimens to confirm the presented inspection method. The experimental results are in good agreement with the analytical results. Therefore, the presented method using frequency domain analysis was confirmed to be a good method for inspecting the electrode conditions in PDPs

In this paper, a modified electric current perturbation (ECP) is presented, which confines an interrogating current to its inspection region and improves inspection sensitivity by using high-frequency current distribution properties. Characterization of a circular aperture, namely, a mathematical model of the induced magnetic flux density for a radius of a circular aperture, is subsequently developed. The proposed method has the advantage that the induced magnetic flux density can be obtained only by integrating over the aperture region, due to the distribution properties. In order to confirm the validity of the mathematical model, experiments are carried out with several specimens, demonstrating close correlation with the mathematical model.

This paper presents a headlamp model that can be used as part of a computer simulation of a wiring system in a vehicle. As more electrical equipment is installed in a vehicle, the wiring system connecting such equipment becomes more complicated, and thus it is essential to conduct a simulation of the wiring system to confirm its capacity. To perform this simulation requires exact models of the electrical equipment fitted to the vehicle. A headlamp model is especially important since currents flowing in the lamp vary dramatically. In this paper, a headlamp model is developed on the basis of the first law of thermodynamics, which is also applicable to a fog lamp. The headlamp is modelled as a variable resistor whose resistance is determined by the change in the operating temperature on account of the applied voltage. The resistance change was simulated using the model, and the resistance of an actual headlamp in a car was measured. Since the complete model is too complex, a simplified simulation model, suitable for use in a computer simulation, is also presented. Comparison of the two results showed good agreement, and through this simulation the reliability of the presented model was confirmed.

Leading-edge discriminators (LEDs) are one of the prominent discriminator technologies used in time-of-flight systems due to their simplicity, but they have large time walks such that the measured time should be corrected using amplitude information. In this article, we analyze off-line time corrections using four kinds of amplitude parameters, namely, peak values, slew rates, and signal widths, as well as charge amounts. For these corrections, we developed the front-end electronics (FEE) that can measure these amplitude parameters and performed time measurements with the developed FEE in an amplitude range of about 20 dB for various threshold conditions, which are the only adjustment in LEDs. Then, we off-line corrected the measured time using the amplitude parameters mentioned above and compared the corrected efficiencies by the used parameters and threshold conditions.

The response time of a comparator involved in a time-pickoff circuit depends on the overdrive and the slope of its input signal, which is the main cause of a timing error. For eliminating the dependency, a time pickoff method employing an automatic gain control (AGC) circuit renders the amplitude of the input signal to the comparator to be uniform. However, its application is limited to the low count rate measurement due to relatively long delay of the nonlinear bias circuit for controlling the gain in the AGC circuit. In this study, a time pickoff method, which employs an automatic gain control circuit with a shorter delay, is proposed for fast count rate measurements. According to the amplitude, the input signal is divided into 4 steps. Then, the gain in the AGC circuit is set to be same for the input signals of the same step, which is basically inversely proportional to the amplitude. This gain setting is performed at one time by amplitude comparison, which is similar to a flash type analog-to-digital converter (ADC) structure, and has a smaller propagation delay. The performance of the proposed method is analyzed through the experiments for input signals with a dynamic range of 40dB.

Time of Flight (TOF) measurement technique of adjacent pulses with sub-nano second interval is presented. In the conventional TOF measurement, the measurement of adjacent pulses is restricted to dead time or recovery time of a single TDC circuit. In the proposed TOF measurement technique, adjacent pulses are distributed to multiple TDCs in the order of arriving sequences in the distribution system. Thus measurement time is not restricted to the dead time or recovery time of a single TDC circuit. In the distribution system, programmable delay circuits are used to optimize the timing of the system so that minimum interval of measurable adjacent pulses is optimized. In this paper, the configuration and modules for measuring adjacent pulses are explained in section I, and various topologies for distribution system are explained in section II. The hardware implementation is considered in section III. And finally the conclusion and future works are presented in section IV.

In this paper, 3 types of preamplifier for MRPC (Multi-gap Resistive plate chamber) are developed and compared in the performances. The main role of the front-end electronics (FEE) for MRPC is to measure the arrival time, which means the time when the particle goes through MRPC. So preamplifier used in the FEE must have a good time performance such as a small propagation delay jitter and fast rise time. We develop 3 types of preamplifier using voltage-feedback op amp (VFA), current-feedback op amp (CFA) and transimpedance amp, respectively. We make performance test with 3 types of preamplifier, including jitter, rise time, linearity, noise figure and input impedance and compare results of performance measurements. With the test results, current-feedback noninverting amplifier is suitable for MRPC.

Time pickoff method by using the automatic gain control (AGC) is presented to reduce the timing walk for a multi-gap resistive plate chamber (MRPC). Due to both variations in the size of the signal and the slew rate of the signal, triggering by threshold level for time measurement is subject to problems of time walk. In addition, comparator response time is a function of the signal slew rate and this is the dominant timing error in the CFD and the zero-crossing discriminator. We add the AGC circuit between the preamplifier and the discriminator in the front-end module (FEM) so that the signals have the same size and the same slew rate. We show the feasibility of this time pick-off method with AGC using the SPICE circuit analysis program.

Triggering by threshold level for time measurement is inherently subject to problems of time walk. In this paper, we discuss timing compensation methods, in order to minimize the effect of time walk, using slew rate, peak value, charge amount and width of signal in the front-end electronics for a multi-gap resistive plate chamber (MRPC). In order to perform these timing compensations, the front-end electronics contains a preamplifier, 4 time-to-digital converters (TDC), a peak detector, a charge integrator and interface circuitry for control and data transfer to a computer. We make performance test of the front-end electronics with simulated signal in the laboratory and correct arrival times with measured data. Timing compensation using charge amounts has small standard deviation. A irrelevantly to threshold levels. Timing compensation using slew rate is preferred for the large difference of threshold levels and timing compensation using signal width at the high threshold level.