The in-circuit test is performed by pushing a needle-type probe into the printed circuit board (PCB) and measuring the conductivity between the electronic components. To reduce the testing time and improve the test reliability, a swift and stable motion of the probe is required, especially when the probe touches the surface of the PCB. Instead of the conventional method involving the use of a force sensor, this study investigates the application of a micro electronical mechanical systems accelerometer to realize the quick contacting motion. The detection of the contact instant is evaluated by the jerk signal from this device. Subsequently, a negative force is added to the probe and the proposed force control based on acceleration aided Kalman filter and reaction force observer is applied. The experimental verification indicates that the settling time is reduced to approximately 10ms and this corresponds to nearly 1% of the comparison data based on the existing technique.

Coasting is a fuel-efficient driving technique for hybrid vehicle that increases cruising distance by separating the engine using a clutch. When a driver needs to accelerate a vehicle in the coasting mode, the engine restarts and the clutch is engaged automatically. At this time, clutch engagement shock and re-acceleration time delay are uncomfortable for the driver. Generally, a hybrid vehicle is regarded as a two-inertia system with a clutch and backlash. This paper proposes backlash-based shock isolation control that isolates clutch engagement shock from a vehicle using gear backlash. The proposed method reduces shock by gently meshing gear backlash using speed difference control between the input and output sides of gear backlash. Thereafter, vibration suppression acceleration is performed through I-P-I-P type torsion torque control. The magnitude of the shock is quantitatively evaluated based on jerk, which is a derivative of acceleration. The effectiveness of the proposed control method is confirmed through numerical simulations and small simulator experimental results. In the experimental results, a 62% reduction in jerk is obtained using the proposed method.

This paper proposes a high-precision, high-speed scanner using a hybrid reluctance actuator, which can be stronger than conventionally used comparable Lorentz force actuators. For compactness, its mover is guided by flexures and laterally moved by a hybrid reluctance actuator with a voltage amplifier. To reject disturbances such as thermal drift and hysteresis, the scanner is regulated by cascade control, for which parasitic resonances are damped partially mechanically. As a result, the closed-loop system realizes a high control bandwidth of 3.5kHz and a high positioning resolution of 0.8nm at a static point. For high-speed scanning motion, modeling-free inversion-based iterative control (IIC) is proposed to be combined with the cascade control as the scanner's feedforward controller. Experiments demonstrate that the scanner with the cascade control realizes a 2µm triangular motion at 400Hz with a tracking error of 101nm, and the modeling-free IIC successfully decreases this relatively large error by a factor of 26 to 3.8nm. Consequently, this paper clearly demonstrates that the proposed scanner with the hybrid reluctance actuator can realize high-precision, high-speed scanning motion.

Repetitive operations are widely conducted by automatic machines in the industry, and the periodic disturbances induced by such operations are a concern as they hinder the proper functioning of these machines. A periodic-disturbance observer (PDOB) has been studied previously to compensate for the periodic disturbances. This observer is a two-degree-of-freedom controller based on the observer structure estimating a periodic disturbance. However, the PDOB does not take aperiodic disturbances into account because it focuses only on periodic disturbances. This paper proposes an enhanced PDOB to enable the PDOB also to compensate for aperiodic disturbances. The enhanced PDOB is constructed by combining the PDOB and disturbance observer. Experiments were conducted using a multi-axis manipulator to compare the PDOB with the enhanced PDOB. The experimental results demonstrate the validity of the proposed method.

A thermoelectric device called a Peltier device is widely used in many fields. For example, the device is used for a cooling system such as in systems consisting of medical reagent coolants and refrigerators. However, controlling the device is difficult because thermal characteristics of the device change depending on its temperature. Notably, the amount of heat flow generated from the device varies with the amount of current applied. Therefore, a thermal nonlinear behavior has to be considered in a thermal model. Most studies do not consider the nonlinear characteristics and treat the device as a linear system. Therefore, robustness against disturbance is not high because of modeling error. This paper presents a heat disturbance observer considering the nonlinear characteristics of a Peltier device. Variable parameters depending on the temperature and current of the device are used, and a variable heat disturbance observer is proposed. The thermal model used in the proposed observer includes a few nonlinear elements such as Joule heat and heat flow inside the device. The objective of this study is to improve the response of a Peltier device. Some experiments were conducted to verify the validity of the proposed method. Besides, the effect of modeling error on the stability of the observer is discussed.

This paper evaluates the performance of a hybrid reluctance actuator for application in high-precision motion systems. For this purpose, its properties are compared with those of a voice coil actuator, which is the choice actuator for many high-precision applications. To properly investigate the non-linearities of these systems, finite element analysis (FEA) is employed. Spacial-domain analysis shows that the hybrid reluctance actuator can deliver both higher forces per volume (by a factor up to app. 10.5) and thrust constant (by a factor up to app. 9.6) than the voice coil actuator. However, these values depend strongly on the position of the mover, causing a high non-linear stiffness. Frequency-domain analysis yields the power losses of the actuators, as well as the dynamic thrust constant. It is shown that at all frequencies the hybrid reluctance actuator suffers from higher iron loss (by a factor up to app. 5.1) than the voice coil actuator. Additionally, its thrust constant shows a large magnitude slope (app. -14.4dB/dec) and phase lag (app. -71^° at f=10kHz) in the frequency domain, resulting in a narrowed control bandwidth. These results clearly indicate a trade-off between thrust constant, linearity and dynamic behavior, which should be considered for employment in high-precision applications.

This paper describes the development of an angle measurement system using a monocular camera. In recent years, the measurement of the angle of a human joint has played an important role in various fields. Particularly, in the area of rehabilitation, measurement results are applied to make a diagnosis based on the condition of the patient; therefore, high accuracy is required. However, the use of such results is limited because systems with sufficient accuracy are expensive and bulky. In the proposed method, we introduce a Moiré pattern that magnifies small angular displacements to compensate for the poor resolution of the camera. We experimentally verified the robustness of the measurement results' assuming practical use.

Mechatronic imaging systems, ranging from nanoscale metrology to telescope systems and adaptive optics for astronomy, are complex machines that demand continual improvement of system speed, range, and precision. This demand requires advanced designs of the mechatronic components and a motion control scheme that carefully considers the interplay of a physical plant and the target application. A proper data acquisition system is required to synchronously acquire and process measurement and position data, and a sophisticated system integration is needed to obtain the maximum performance of the resulting system. This paper discusses the interplay between process and control design, as well as the system integration with the example of a scanning laser triangulation system for high precision 3D metrology. The integration process can be tailored to individual applications, and is discussed for raster and Lissajous scan trajectories, considering their individual requirements for the system and control design. Further it is demonstrated how these individually tailored system components can improve the performance in terms of precision and efficiency by several orders of magnitude.

The development of high-performance mechatronic systems as well as the strong demand for environment-acceptable and safe intelligent technologies have had a profound impact on vehicle engineering. This impact has resulted in both an increasing degree of automation of vehicular systems and the emergence of new concepts like integrated chassis control. To contribute to this topic, a consortium of several industrial and academic partners from EU, South Africa, and USA has performed consolidated research and innovation actions for the development of new integrated chassis control technologies within the framework of the European project EVE. This paper presents the main EVE outcomes related to the integration of active brake, suspension, and tyre pressure control. Attention is also given to the problems of vehicle and tyre modelling, state estimation, robust chassis control, and experimental validation tools.

This paper presents a design methodology of a Kalman filter for a multirate control system with a fast input system. There are many applications whose sensory system is slower than the input system in a power system. The sensory system is required to perform fast sensing while ensuring a low signal-to-noise ratio, although it requires additional time compared with that of a low-resolution converter. The Kalman filter is an effective tool in such a situation and it estimates parameters while eliminating noise. Because the optimality of this filter is ensured when the system model and noise variance on the system are well identified, rigorous discretization should be considered on the multirate control system. With this in mind, the paper presents the design method of a multirate Kalman filter as is the case for a single-rate controller. Further, the noise variance and oversampling ratio of the multirate controller is confirmed using the Monte Carlo method. Numerical simulation of a voltage inverter theoretically validates the design methodology.

A classic example of dynamic systems with nonlinearities is considered, using an electrical circuit including the tunnel diode, that features several equilibria points due to a piecewise positive and negative damping. These system-properties allow us to investigate the possible limit cycles, and the formal analysis of the closed-loop dynamics of such. In this paper, an experimental setup of nonlinear circuits is designed, followed by the system modeling and identification of the diodes' characteristics. An integral-state-feedback control is designed and evaluated for demonstrating the appearance of the limit cycles depending on the reference level. A piecewise affine (PWA) system formulation is also provided for allowing the use of formal verification tools for hybrid dynamic systems. An available tool, PWLTool, is applied in line with trajectory prediction from the numerical simulation of the identified closed-loop system.

In motor drive applications, a high switching frequency is required to mitigate current harmonics, which cause a copper loss. However, the high switching frequency makes the switching loss large. Hence, some switching loss reduction techniques have been studied in the past. These techniques have some problems. This paper proposes a multilevel inverter topology for switching loss reduction. Because of provision of multiple current paths, the proposed inverter realizes the zero current switching. Consequently, a loss of the whole system including an inverter and motor can be reduced with a higher switching frequency. The switching loss of the proposed inverter is smaller than that of the conventional one. It was verified that the proposed inverter has some advantages at high switching frequency, through calculations.

Almost all motion control systems have low-stiffness parts, and exhibit resonance characteristics. In many cases, we use the systems at a lower frequency range than the resonant frequency. However, in some cases, we have to use them in the same frequency range as that of the resonance. Various researches have been conducted to suppress the vibration of resonant systems with feedback controllers. They are very effective, but we need to design dedicated controllers with special capabilities. On the other hand, a feedforward controller can change the zeros of the system, which in turn suppresses the vibration. In this paper, two examples that demonstrate the effect of feedforward controllers are introduced. They change the reference response of the systems and the limited pole placement method, which assigns the representative poles precisely, is used to assist the effect.

High-precision stages are widely used for manufacturing semiconductors and flat panels. These high-precision stages have become multi-input multi-output (MIMO) systems with six-degrees-of-freedom (DOF); hence, the coupling between the translation and pitching motion deteriorates the control performance. This study proposes the multirate feedforward control for MIMO systems and applies it to these high-precision stages. The multirate feedforward control designs the stable inversion for the unstable discretization zero problem. In addition, the design of the MIMO multirate feedforward controllers has a degree of freedom to design the B matrix according to the selection of the generalized controllability indices. In conventional control methods such as precompensated decoupling controllers, it is theoretically impossible to achieve perfect tracking because unstable discretization zeros are generated. In this study, the proposed method is applied to the translation and pitching motion of a high-precision stage, and it achieves perfect tracking in the simulation. The effectiveness of the proposed method is verified experimentally.

Relay feedback systems belong, since long, to the rather classical topics of control theory and engineering. While they were first used as robust and simple switching elements in automatic control systems, over time, they have experienced different periods of renewed interest with regards to both theoretical analysis and applications. Examples include the automatic tuning of simple feedback controllers, delta-sigma modulators for analog-digital converters, robust relay-based controls, nonlinear systems analysis and identification, among others. One of the remarkable features of using relays in feedback is the appearance of stable limit cycles. The structural and parametric conditions for the stable limit cycles, their prediction, and controllability of magnitude and frequency have already been solved, to a large part, in previous researches, driven by both theoretical curiosity and application requirements. This brief tutorial paper summarizes the basic principles of relay feedback systems, discusses several characteristics that are interesting from an application perspective, and addresses some issues related to its further use for system identification. A case-specific study for estimating the unknown backlash, hidden within two-mass systems, is demonstrated along with an experimental example, based on provoking the controllable drifting limit cycles by the non-ideal relay in the velocity feedback loop.

Electro-hydrostatic actuators (EHAs) are hydraulic systems that operate without control valves, making them a compact, cheap, and highly energy efficient system. However, resonance, static friction, and oil leakage degrade their control performance. Three controllers are integrated to overcome these issues. First, static friction is suppressed by a feedback modulator (FM). Input torque is quantized to exceed the maximum static friction force, and quantization errors are suppressed by the FM. Second, resonance is canceled out by a self resonance cancellation (SRC) technique. In the SRC, both angle responses of a hydraulic pump and a hydraulic motor are measured, and the rigid body mode is extracted. Then, resonance becomes unobservable, changing the system as a second-order system. Third, modeling errors, including oil leakage, are suppressed by a self resonance cancellation disturbance observer (SRCDOB). As the SRCDOB is implemented in the rigid body mode, the cut-off frequency of the SRCDOB can be greater than that of most common disturbance observers. This combination of controllers drastically improves the control performance, and it enables control system design based on frequency.

This paper studies the application of common-mode voltage injection techniques typically used in two-level inverters (carrier-based space-vector modulation and flat-top modulation in particular) to quasi-two-level PWM-operated modular multilevel converters. Similar to two-level inverters, the available operating area is extended to higher modulation indices. The properties of the respective techniques are compared to each other and to the modular multilevel converter in the normal operation mode. The results are based on simulations and the model is partly experimentally validated on a downscaled converter prototype.

This paper proposes a new field bus protocol based on the IEEE 802.3 Ethernet standard. The protocol enables fast data exchange between the modules and synchronised control in the modules of modular power electronic systems. With increasing switching frequency, a highly accurate synchronisation of the different modules is a necessary requirement for a control bus. The proposed field bus protocol provides a stable and efficient scheme including a novel data frame structure and allows the realisation of a synchronisation accuracy of ±4 ns based on the 1GBit Ethernet standard. For validation of the new protocol, a prototype system was developed and the measurement results are reported herein. The results show that the implementation satisfies the specifications. Finally, different use-cases and the achievable data rates for the given implementation were derived.

Maintaining the operating junction temperature of a SiC Power MOSFET within a safe and tolerable range is crucial not only for safety reasons, but also for reliable operation, as thermal transient is one of the major stressors that threaten a device's life span. Conventional methods use thermal sensors for temperature monitoring. However, these sensors require extra space, and the measurement accuracy is affected by their position. Besides, they are unable to track the transient temperature variation owing to relatively slow response time. This paper proposes a new temperature sensor-less method to estimate the junction temperature of SiC power MOSFETs by measuring the device's turn-on saturation current (I_D,sat). The device's square root of the saturation current (√I_D,sat) and threshold voltage (V_th) can be extracted and adopted as junction temperature estimators. Compared to the threshold voltage, the square root of the saturation current has the advantage of a shorter test time. The feasibility of this temperature estimation method has been experimentally verified. The results suggest that the proposed method can be used as an alternative for effective online junction temperature monitoring.

A disturbance-robust current control technique for large-scale PV inverter whose rating is several hundred kW is described. The biggest disturbance against current control of grid-connected inverters is the grid fault. The goal of this development is set as to be able to ride through three-phase grounding faults whose residual voltage is down to zero. The main development point of the scheme is to introduce sophisticated voltage feedforward control and improved sampling technique in the current control system. The idea is to make the AC output voltage of the IGBT assemblies follow the quick change in the grid voltage with a small time delay in order to reduce the AC current overshoot caused by grid faults. The validity of the control scheme is confirmed by a simulation study and full-load fault-ride-through tests.

This paper focuses on back-forward drivability and defines the ideal drivability. This paper proposes a new back-forward drivable control method that achieves vibration suppression while maintaining back-forward drivability for a two-inertia system. The proposed control system combines torsion torque control (TTC) and a motor-side normalization compensator (MNC) to facilitate human-robot interactions. The effectiveness of the proposed control system is verified based on numerical simulation and experimental results, and the vibration of the back-forward drivable response is drastically suppressed.

This study aims to realize an automated deceleration system to avoid the collision of a vehicle with a pedestrian. The proposed system can predict a pedestrian's future position from the current position, and detect the collision probability. Furthermore, the controller employing model predictive control, which can compensate the driving resistance and the modeling error is also proposed. The effectiveness of the proposed method is verified through a simulation and experiment.

The paper proposes a parameter design of a reaction force observer (RFOB) under existence of modeling error/parameter fluctuation. Observer-based sensorless-force-control is a good approach to reduce phase lag in control systems. Hence, the performance improvement can be easily attained by such a technique. However, the RFOB does not always guarantee accuracy of estimated value and adds incorrect compliance on the system. Due to insufficient report about RFOB design, its calibration is conducted based on the designer's own experience. To calibrate the RFOB and achieve the correct force control quantitatively, the structure of the observer-based force control and physical interpretation of control loops should be revealed simply. The paper presents a condition to achieve the correct force control and design methodology of observers, thereby, providing a robust performance against parameter variation.

This paper proposes a constant dc-capacitor voltage-control (CDCVC)-based reactive power control strategy of a static synchronous compensator (STATCOM) with a three-level neutral-point-clamped (NPC) inverter, in which the source-side harmonic currents are also compensated. The CDCVC-based reactive power control strategy uses only a CDCVC, which is always used in the grid-connected inverters, STATCOMs etc. Calculation blocks of fundamental active, reactive, and harmonic components are not needed. Thus, the authors offer a simplified strategy for a source-side reactive power control with source-side harmonic current compensations. The instantaneous power flowing into the STATCOM with a three-level NPC inverter is discussed in detail. The instantaneous power flow shows that using the CDCVC-based strategy for the STATCOM achieves sinusoidal source currents using the controlled source-side reactive power compensating the harmonic currents on the source side. A digital computer simulation is implemented to confirm the validity and high practicability of the CDCVC-based strategy. A reduced-scale prototype experimental model is constructed and tested. The simulation and experimental results demonstrate that sinusoidal source currents are obtained with the CDCVC-based strategy controlling the reactive power on the source side.

Owing to the significant advances made in the field of power semiconductor devices, such as SiC and GaN, the switching frequency of power converters has been increased. Thus, the volume of passive components such as filter inductors and transformers can be reduced. However, the reduction in the heat-dissipation surface area of inductors results in a considerable increase in temperature, which is a constraint for increasing the power density of power converters. To prevent these problems, the iron-loss evaluation of inductors is one of the most important issues in realizing high-power-density converters. This paper presents an accurate iron-loss calculation method for inductors considering the non-uniformity of the flux-density distribution in the magnetic core. First, it is verified that the non-uniformity of the flux-density distribution in the core results in the deviation of the iron-loss measurement even when the same magnetic material is used in the core and when the inductor is excited under the same excitation condition. Next, the procedure to obtain the iron-loss data, which describes the relationship between the iron loss and excitation condition more precisely, is introduced. Finally, a method to accurately calculate the iron loss in an inductor using electromagnetic simulation and more precise iron-loss data is introduced. method is verified using a toroidal core and a UU core under sine voltage condition and rectangular voltage condition.

Nowadays, many passengers rely on transfer guidance systems and their demands for punctuality of trains have become very high. In order to satisfy passengers' requirements for punctuality, it is necessary to establish an approach that can help deternining where delays occur and the type of delay reduction measures to be taken to reduce delays most efficiently. We have established functions to acquire and record the departure and arrival times of all trains in seconds at all stations. Based on these data, we introduce two indices that will be useful in deternining the places where delay reduction measures should be taken and the most effective delay reduction measures. We have applied this approach to the Hanzomon line, which is one of the most congested lines and small delays occur frequently. The results indicate that the proposed approach considerably reduced delays.

Recently LED lighting apparatus are becoming more popular and well received by users. An offline LED apparatus needs to have electrolytic capacitors inside to supply LEDs with a regulated DC voltage. Although LEDs are characterized by longevity, the shorter lifetime of the constituent electrolytic capacitors limit the lifetime of the LED lighting apparatus. That means that actual LED lifetime is being wasted, consequently wasting the manufacturing cost. This paper proposes a new LED drive circuit topology, which does not need any electrolytic capacitors and shows the simulation results of the circuit. Also described are simulation results of its efficiency, the power factor, and EMC characteristics without any reactance at the line interface. From the simulation results, it is shown that the circuit topology has the potential for practical use.