Road traffic accidents are a leading cause of avoidable deaths, especially among young persons. Because driver behavior is a major cause for these the incidents, any device able to help the driver should lower casualties. As an intermediary step between autonomous vehicles and human driven ones, active driving assistance technology can help the driver maintain a safe trajectory. Applying remote control to vehicles could also decrease the probabilities of accidents, by facilitating the reduction of the duration of the driving sessions, especially in fret transport applications, decreasing drowsiness of the driver, a factor that increases the occurrence of accidents. However, the addition of remote control conducts to a communication time delay that can be dangerous in cruising situations. This paper presents the application of an active driving assistant to compensate for the effects of the communication time delay in collision avoidance scenarios using a small-scale vehicle.
We experimentally and numerically investigate the magnetic properties of magnetic materials excited by sinusoidal and pulse width modulation (PWM) inverter input at high ambient and room temperatures. We show that the iron losses under sinusoidal and PWM inverter excitations decrease with an increase in temperature. It is found that the temperature dependency of iron loss properties is related not only to major loop but also to minor loops. Furthermore, we derive the numerical expression for the hysteretic properties of the PWM inverter- and sinusoidal-fed ring tests at room temperature and 300°C by using the play model with the Cauer circuit.
This paper presents a novel dynamical modeling method for magnetic actuators. The magnetic field is decomposed into orthogonal distribution functions by using the Cauer ladder network representation of eddy-current fields. The linearized transfer function of the magnetic force is derived by using the Maxwell's stress tensor and distribution functions. The numerical example of an electromagnet is presented to show the effectiveness of this method. It is revealed that the eddy current not only reduces the main flux but also induces a repulsive force at the air gap. The details of the Cauer ladder network representations are also clarified.
This paper deals with magnetic levitation techniques for the steel processing industry. Adopting such techniques is a beneficial way to maintain the high quality of steel surfaces. However, control for the levitation and guidance of the thin steel plates is not so easy, because of their mechanical and electromagnetic characteristics. In particular, the thinner the steel plate, the more difficult it is to control its levitation, guidance and conveyance. We already established stable magnetic levitation and guidance control for 1.6mm-thick steel plates. In this paper, we aim at establishing stable magnetic levitation for a 0.1mm-thick steel plate, which has thinness similar to paper. In order to realize such a noncontact system for 0.1mm-thick steel plates, we have to take account of its vibration and magnetic saturation and leakage. This paper details a methodology for stable magnetic levitation and guidance, and shows many successful experimental results for such a paper-like thickness of a steel plate.
In this study, we evaluate the iron losses in amorphous magnetic materials (AMM) and non-oriented (NO) rings excited by different inverters that use conventional and next-generation semiconductors. We examined the iron loss characteristics of the AMM ring as a function of carrier frequency when the ring was excited using two inverters. One inverter was a silicon-based insulated gate bipolar transistor (Si-IGBT) and the other was a gallium nitride-based field effect transistor (GaN-FET). We also compared the NO ring under these two inverter excitations. Due to the skin effect, the iron losses of the NO ring decreased with an increase in the carrier frequency under Si-IGBT inverter excitation. The AMM ring remained almost unaffected by the skin effect in the 1-20kHz range; therefore, it is thought that the iron losses based on the AMM ring test fed by the Si-IGBT-inverter had an almost constant value. Under GaN-FET inverter excitation, the iron losses at high carrier frequencies increased because the number of times of ringing derived from the high-speed switching increased. We have shown that the influence of ringing in the AMM ring becomes large in comparison to that in the NO ring because the losses in the AMM ring are less than those in the NO ring in the high-frequency region.
This paper conducts a comparison between direct and indirectly liquid-cooled topologies for coreless linear motors with multiple coil layers. The electromagnetic force production is obtained by 3-D magnetic scalar potential modeling whereas thermal modeling is performed by 3-D finite element and volume methods. The power dissipation and force density of each topology is investigated for different pole pitches and coil configurations. Subsequently, localization and comparison of the magnetic and thermal stresses is performed for both topologies. Furthermore, variations in the geometry are investigated to mitigate mechanical stresses.
The paper describes a 3D semi-analytical harmonic modeling technique that is capable of modeling eddy current distributions in segmented conducting structures, such as slitted conducting plates, and the associated magnetic fields. The spatially varying conductivity of a conducting region is incorporated into the solutions of magnetic-field quantities and the induced current density. The harmonic model is compared to results obtained with finite element analysis. An experimental setup is used to measure the field distribution above differently slitted conducting plates, in which eddy currents are induced by a coil. The measurement results are compared to simulation results, and the perturbations are analyzed.
A linear generator system is expected to realize a highly efficient free-piston generation engine. The efficiency of the system mainly depends on the generation and thermal efficiencies of the engine. The generation efficiency decreases owing to a large braking force on the expansion stroke and a speed reduction at the ends of the stroke. This paper proposes generation control with resonance and output drop that improves the generation efficiency during the expansion stroke. When changing the amount of consumed fuel, the condition to maximize the electricity generation can be achieved by optimizing the ratio of the iron to copper losses. Furthermore, the proposed method improves the combustion performance of the engine by ensuring ideal speed at the combustion start position.
A free-piston engine linear generator (FPEG) system is a linear generator, which generates electricity when a free piston reciprocates the combustion thrust produced by internal combustion. It is expected that this system can be applied to hybrid vehicles. In an FPEG system, the high combustion energy is instantly added to a free piston. Nevertheless, it is difficult for a linear synchronous generator (LSG) to convert combustion energy into electric energy by using the output of the LSG given the limit of the inverter capacity. Hence, it is necessary for an LSG to convert combustion energy into electric energy while distributing the combustion energy in one stroke. Moreover, if an LSG is driven at high velocity and high thrust within the limit of an inverter capacity, then the LSG converts the high combustion energy into electric energy. In this study, we propose a configuration of an LSG with a typical output of 10kW and a generation efficiency of 97% for an FPEG, and we evaluate its static thrust and magnetic flux density distribution using finite element method (FEM) analysis. Moreover, we examine the driving range of the LSG for an FPEG system.
This paper discusses the effectiveness of using Updating Final-State Control (UFSC) for Automated Guided Vehicle (AGV) collision-avoidance problems, as an example of rigid body motion control problems that have time-varying states. This paper broadly comprises two parts: 1) clarification of the characteristics of the UFSC through numerical simulations in an ideal system and 2) experimental demonstrations. Regarding the former, this paper performs several numerical simulations and demonstrates the effectiveness of the UFSC through comparison with other methods: PID (Proportional-Integral-Derivative) control with a safety length constraint and MPC (Model Predictive Control). The results show the acceptable performance of the UFSC. In addition, the UFSC has some advantages with respect to the computation time, the effort required for control parameter tuning, and the performance retention of prior obstacle's information and control parameters. For the experimental demonstrations, the authors add the realistic frictions, corresponding to the controlled object, to the one-dimensional model. The experiments are performed under four different conditions, and their results show the validity of the numerical simulations. The discussion in this paper supports the acceptable performance and effectiveness of the UFSC for these types of problems.
In this paper, we propose a method for improving the positional accuracy of a stepping motor in micro-step drive by just modifying a reference angle using the proposed pre-compensator. For a given reference angle, the pre-compensator outputs the modified reference, which cancels the positional error due to the torque ripples and friction. To validate this method, position control experiments were carried out with and without the pre-compensator. The results demonstrate that the positional accuracy of micro-step drive with the pre-compensator is significantly better than that without the pre-compensator.
High-frequency switching techniques enable the miniaturization of inductors in non-isolated DC/DC converters. However, higher frequency converters cause large switching power losses. This paper proposes a design method for a high-frequency, non-isolated buck DC/DC converter with a passive soft-switching circuit. The calculation results of the converter revealed decrease in power losses compared to that of a hard switching converter, for over 50kHz. A 2.1kW prototype was designed for reification, and it achieved a power efficiency of 95.6%.