The rapid expansion of the semiconductor industry and the increasing demand for high speed, high precision positioning stages necessitate exceptionally precise active control of pneumatic vibration isolation tables. This study addresses these stringent requirements by employing a novel pneumatic valve to regulate airflow to the air springs of the vibration isolator. The novel valve incorporates an internal sensor for accurate poppet position monitoring which enables inner loop feedback (FB) control of the poppet position. This effectively compensates for airflow induced disturbances acting on the poppet. Consequently, rapid and precise air spring pressure regulation is achieved which results in accurate displacement control of the vibration isolator. The effectiveness of the proposed system is validated through experiments evaluating its ability to isolate vibration caused from a movable stage mounted on the isolator.

Reliable interruption of high fault currents in compact DC systems remains a key technical challenge, especially for next-generation power electronics and mobility applications. This study aims to develop a robust interruption strategy by coordinating a current-limiting fuse and a pyrofuse through active sensor-based control. Especially, by estimating the current-limiting fuse resistance in real time from voltage and current measurements, the system accurately identifies the completion of current-limiting and operates the pyrofuse at the optimal moment. Experimental validation confirms that a 750V DC fault can be interrupted within 3.4ms using compact, low-cost hardware. The proposed method offers a reliable control method for DC fault protection in powerful, space-constrained applications.

Train localization is a crucial technology in the railway industry, with increasing demand for cost-effective methods that eliminate reliance on ground-based equipment to reduce both costs and maintenance requirements. In this study, we propose a versatile train localization method applicable across diverse environments, including high-speed railways, conventional lines, urban settings, and rural areas. By integrating a high-speed, cost-effective one-dimensional LiDAR sensor with GNSS, MEMS IMU, and a Tachometer generator, the system can effectively recognize the surrounding environment and accurately determine the train's position. The proposed method ensures low-cost and high-accuracy train localization even in areas with dense surrounding structures or open-sky environments. Experimental results conducted on operational railway lines demonstrated a high success rate of 97 % in recognizing the surrounding environment and detecting train location using this approach. Moreover, the accuracy of train localization achieved through this method was found to be comparable to that of a loosely-coupled GNSS approach.

Compact and cost-effective DC circuit breakers are becoming increasingly crucial as the prevalence of household solar panels and electric vehicles for a sustainable society. For this demand, a current-limiting fuse, which can limit current flow, and a pyrofuse, which physically interrupts circuits by detonating gunpowder, have been focused on as practical and compact components. This paper presents an active control of a pyrofuse in a compact circuit breaker consisting of a current-limiting fuse and a pyrofuse in series connection. The system interrupts fault currents by first limiting the current through the current-limiting fuse and then activating the pyrofuse to interrupt the circuit. The pyrofuse is activated based on a real-time estimation of the current-limiting fuse, developed in our previous research, which detects the end of the current-limiting by utilizing a real-time current data. This system safely interrupts fault currents that each component alone is unable to handle. The effectiveness of this breaker has been validated through experiments, with the interruption of a fault current of 1.7 kV and 10 kA occurring within 8.3ms.

Hybrid DC circuit breakers have become a critical choice for ensuring safety in modern DC transmission and distribution systems. In this paper, we validate a current path control strategy in the fuse-semiconductor hybrid circuit breaker. This strategy utilizes an RC circuit model to describe the arcing current of the fuse and applies the Recursive Least Squares (RLS) algorithm to minimize the difference between the modeled current and the observed current data in real-time. By presenting the fuse’s current-limiting state in real-time, this method effectively prevents re-arcing and potential fuse explosions. Our approach addresses the limitations of the predetermined current threshold method, enabling a more accurate current model in complex situations. The proposed strategy was experimentally validated under extreme conditions of 1.7 kV and 10 kA fault currents, demonstrating its robustness and reliability.

Semiconductor vertical furnaces are used in the semiconductor manufacturing process to perform deposition and oxidation on wafers. To increase the equipment throughput, a shorter process time is one of the criteria needed. To achieve this, this paper presents a control method consists of fast mode and tracking mode. The fast mode utilizes the maximum capacity of the actuators and is implemented as time-optimal control using binary search algorithm. The tracking mode is introduced to maintain constant temperature and deal with inaccuracies in the fast mode caused by plant unmodeled dynamics and time discretization. It is implemented as a two-degree-of-freedom control. Simulation results have shown that shorter rising time and settling time can be achieved by the fast mode and tracking mode respectively, resulting in the reduction of total process time.

In this paper the Indian Railway traction network is analyzed. Indian Railways gets its traction supply from the state-owned utility grid. With the shift in policy to manufacture only 3-φ locomotives in the future, there shall be enhanced feedback of regenerative braking energy (RBE) to the grid especially in the absence of another 3-φ locomotive to absorb this RBE. This can negatively impact the utility grid (due to the harmonics in RBE) and presently there is no provision to get remunerated for this reverse flow of energy. Thus, it is essential to efficiently utilize this RBE in the railway network itself. This can be achieved by adopting bilateral co-phase traction network configuration which can enhance the utilization of RBE. However, by making the traction supplies co-phase in adjacent traction substations there is a pronounced effect of circulating currents which can offset any advantage obtained due to RBE utilization. In this paper the feasibility of adopting bilateral co-phase traction network is examined by demonstrating the impact of difference of voltage magnitudes and phase angles on effective RBE utilization. The ideal range of these parameters for saving RBE is also demonstrated. A case study is done based on realistic data from Indian Railways.

To achieve perfect reference trajectory tracking, a plant with continuous time unstable zeros requires an infinite time preactuation. However, literal infinite preactuation is practically infeasible. Preactuation as short as possible is desirable for high-precision motion systems. This paper, thus, proposes an optimal state trajectory regeneration method without preactuation. The original state trajectory, which requires the infinite preactuation, is generated by preactuation perfect tracking control (PPTC) method. Then we regenerate the state trajectory between the start and end time of the reference motion trajectory. This method is an extension of the method of a finite preactuation perfect tracking control (FPPTC) method. In the FPPTC method, perfect tracking after preactuation is guaranteed by regenerating the state trajectory during preactuation, whereas the proposed method of this paper guarantees only after the end of the reference motion. The state trajectory during the reference motion is optimized with respect to the control input and plant output constraints. A multirate feedforward scheme, which is a stable inversion for unstable discretization zeros, is subsequently presented to obtain a discretized control input that perfectly tracks the designed optimal continuous state trajectory.

The most critical problem in high-precision stages for semiconductor and LCD manufacturing is cable disturbance, which can be caused by power cables and communication lines. In our previous study, we designed a novel single-axis high-precision stage using wireless power transfer technology, which avoids cable disturbance. Here, we further develop this concept and propose a multi-axis wireless high-precision. Experimental results demonstrate the effectiveness of the multi-axis wireless high-precision stage.

Semiconductor and LCD manufacturing equipment, which needs to position the stage in high-speed and high-precision, has been developed on both the mechanism and control. The experimental results, however, is often different from theoretical results because of a cable disturbance caused by such power cables and communication lines. Therefore, in order to eliminate the high-voltage cable disturbance, this paper proposes a next generation high-precision stage with lightweight moving coil type linear motor powered by wireless power transfer via magnetic resonance coupling. The experimental results demonstrate effectiveness of the proposed high-precision stage.

A pneumatic actuator has several advantages such as low heat generation, high weight power ratio, and low cost. However, it has several disadvantages such as time delays and nonlinearities. Because pressure and position feedback band-widths are limited by the time delay problem, it is difficult to implement a pneumatic actuator for a scan stage. Therefore, this paper proposes a modified Smith predictor for it and implements for an experimental scan stage. The effectiveness of the proposed control system is validated by frequency and time domain experiments.

High-precision stages are used for the fabrication of integrated circuits, liquid crystal displays and so on. Since higher integration density and product quality are continuously required for the development of industry and informatics, not only the stage position but also the stage attitude needs to be controlled rapidly and precisely. The attitude is determined by roll, pitch and yaw motions which are affected by nonlinearity and coupling caused by Euler's equation and rotational kinematics. These effects deteriorate the attitude control performance. This paper proposes a MIMO nonlinear feedforward attitude controller which compensates such effect. The effectiveness of the proposed approach is verified by simulations and experiments.