In recent years, robots are required to operate in various environments and situations. Therefore, robots have to recognize the environment they are in, and adapt to any situations that present themselves. The purpose of this research is to increase the tracking speed and robustness of the visual servoing system. A 3-link planar manipulator mounted with a CCD camera is used to track the target. In order to track the target, an image-based tracking method, suitable for high-speed tracking, is adopted. In this paper, image-space observer (IOB), which compensates disturbances in the image space, is proposed. Then, a zero-order hold is introduced to the IOB to enhance the performance of the visual servoing system. The validity of the proposed method is confirmed through experiments.

View full abstract

This paper describes an improvement in the control method of the boost-type matrix converter for a three-phase four wire system. The system is intended for use in a stand-alone power source with a constant voltage and frequency. The conventional method however is not able to control the output voltage with a low power-factor load. To solve the problem, we propose a new control method the matrix converter by reviewing the conventional control method.

View full abstract

This paper proposes a method to predict the charging current, the output power, and the power transfer efficiency of a low-power non-contact charger with reasonable accuracy. The low-power non-contact charger model considered in this paper consists of a sinusoidal voltage source, a sending and a receiving coil, a full wave rectifier circuit, and an AA nickel metal-hydride battery. The capacitor that is series-connected in the sending coils of the low-power non-contact charger model to improve the power factor was also examined. The self-inductances, the mutual inductance, and the resistances of the coils were calculated by axisymmetric finite element analysis, and were substituted into the circuit equations. The circuit equations were solved by using the Runge-Kutta method. The calculated charging current, output power and power transfer efficiency were in good agreement with the experimental results.

View full abstract

We developed an interleaved DC/DC converter with SiC devices. We applied full-SiC modules including MOSFETs and SBDs to the interleaved DC/DC converter to achieve a high power density. SiC has a high temperature resistance, which facilitates improvement in high-frequency drives. We achieved a high power density by utilizing the high temperature resistance feature. We also fabricated the prototype and tested it with loads up to 65kW.

View full abstract

In this paper, an analytical method applying a mathematical model for switched reluctance motors (SR motors) is proposed. The feature of this method is the expression of the influence of the mutual flux in the integral model by applying a transient analysis using the preprocessed inductance tables. The advantage of the method is shortening of the analysis time in comparison with the finite element method (FEM). The calculation results for the torque exhibit little difference between the FEM and the proposed method, and the computation time was shortened. A 3.7-kW prototype axial-gap SR motor designed with the proposed method delivered the specified performances.

View full abstract

An obstruction warning signal is an important railway signalling piece of equipment used at a level crossing. However, it is not possible to check the visibility of such equipment during the train operating hours, because this would require traffic interruption. In this paper, we propose a method that employs near infrared LEDs, and can check the visibility of obstruction warning signals during business hours. It has been proved that the method which we have developed, namely an image processing method using a near infrared camera and a pan-tilt camera operated by feedback control installed on a vehicle, can track and detect the specific blinking of the signal correctly. Finally, we report the results of the functional field tests.

View full abstract

This paper proposes a new efficient drive method for PMSMs based on optimal servo control theory. The proposed method can directly determine the optimal voltage command and derive new structures of the drive system and the torque controller. The validity of the method is verified by extensive simulations.

View full abstract

This paper discusses a commutation sequence in which the next switching interrupts the commutation. In order to avoid a commutation failure, it is necessary to prevent the simultaneous turning on or turning off of some switches. In particular, this simultaneous turning on or off occurs when four commutation patterns are interrupted during the same commutation period. Thus, the commutation patterns should be considered as the worst case. Improving the commutation sequence increases the efficiency by 1.6%.

View full abstract