Most Industrial robots are driven through reduction gears such as harmonic drives and RV gears. Since the flexibility of the drive system, the vibratory behavior is caused during the operation. When the flexibility is considered, the drive system of the robot joint can be modeled as a resonant mechanical system called two-inertia system. Conventionally, studies on two-inertia system discussed semi-closed loop control using only motor information and state observer. On the other hand, joint torque sensing of robots are studied on harmonic drives, which are used in robot joint widely. The joint torque sensor is becoming available with higher performance. In this paper, we consider the control of robot arm having two-inertia resonance by using joint torque sensor. The performances between torque sensor and obserber are compared.
Image template matching is applied to various fields such as industrial image applications. Increment Sign Correlation (ISC) is one of image template matching methods. This method is robust to shading and occlusion. This paper proposes a method for image template matching that is based on Directable Increment Sign Correlation (DISC). ISC compares gray-levels of neighboring pixels to the horizontal direction. In the proposed method, the pixel with the maximum difference of gray-level between an objective central pixel in eight neighboring pixels. The experimental results show that the proposed method is robust to inclination, noise, occlusion and off-focus in comparison with ISC.
As a large number of electronic products such as personal computers are now connected to power distribution lines in commercial buildings, the serious problems such as voltage distortion on utility outlets and excessive neutral current on the distribution lines have arisen. This paper shows control methods and compensation characteristics of a series active filter connected to the neutral conductor. The distinctive functions of the proposed active filter are the mitigation of 3rd-harmonic voltage and reduction of neutral current in a three-phase four-wire distribution system. The required kVA rating of the proposed active filter is less than 10% of that of the harmonic producing loads. A control method of the dc capacitor voltage on the active filter circuit is also described. It is clarified through experiments that one of those two functions of the active filter can be realized selectively and the dc capacitor voltage of the active filter can be regulated to a desired value.
The segment stator core, high density winding coil, high-energy-product permanent magnet are indispensable technologies in the development of a compact and also high efficient motors. The conventional design method for the segment stator core mostly depended on experienced knowledge of selecting a suitable electromagnetic material, far from optimized design. Therefore, we have developed a novel design method in the selection of a suitable electromagnetic material based on the correlation evaluation between the material characteristics and motor performance. It enables the selection of suitable electromagnetic material that will meet the motor specification.
In this paper, we propose a novel approach for stepping forward action of biped robot with minimum kicking force. In walking or starting to walk, the general biped robot kicks the ground with its own hind leg as well as human being does. The condition of the ground often restricts the gait because of stiffness, slipperiness and so on. In order to surmount the difficulty on stepping forward action, we introduce the redundant legged biped robot, which has 4 degree-of-freedoms on each leg. Our robot enables to move its tip position and its center of mass (COM) position independently. Controlling COM acceleration without moving its tip position realizes the stepping forward action with little kicking force. The physical experimental results show the significant validity of the proposed approach.
In this paper, a new universal drive system of synchronous motors used Real-Time Interface (RTI) performs characteristic evaluation of Synchronous Reluctance (SynR) motors and Surface Permanent Magnet (SPM) synchronous motors. The RTI connects directly a simulation model with experimental equipment, and makes it possible to use the simulation model for an experiment. The RTI is very effective in the early detection of an actual problem and examination of solution technique. Moreover, it concentrates on examination of control algorithm, and efficient research and development are enabled. A measuring system of synchronous motors is built by the universal drive system. The examination of various synchronous motors is possible for the measurement system using the same control algorithm. Characteristic evaluation of a SynR motor and a SPM synchronous motor that are the same gap length and stator was performed using the measuring system. The measurement result shows experimentally that motor loss of the SynR motor is smaller rather than the SPM synchronous motor, at the time of high speed and low load operation. For example, the SynR motor is suitable to hybrid cars with the comparatively long time of low load and high-speed operation.
A linear generator, which utilizes harmonic magnetic field by ground coils has been developed for on-board power source for the Electro Dynamic Suspension (EDS) Maglev. The linear generator is composed of generator coils and a PWM converter which can compensate reactive power and control output power by detecting instantaneous current and generating equivalent voltage in a RC circuit. However, in the case of controlling any phase to generate magnetic damping, interference between output and phase occurs and the output fluctuates. This paper examines the output and phase control in the converter of linear generator and proposes the improved method to reduce the interference between output and phase control. By using numerical examples, we reveal the performance of the improved control system, and verify their performance in the bench test.
This paper presents a method to estimate the output voltage of a high speed, surface permanent magnet generator with large air gap length at design stage. The output voltage is estimated by the induced electromotive force and the synchronous inductance obtained from the analytical results of the flux linkage using FEM. Also, a method to classify the synchronous inductance per each causing factor is proposed. The air gap leakage inductance is not negligible in a large air gap machine like this generator. The validity of the proposed method has been proved by the measured values of a generator designed by this method, and also the measured values show that the output voltage of the generator is within the permissible range. The method propose in this paper will be an effective tool to design a high speed, surface permanent magnet generator with large air gap length.
In recent years, low output power CMOS DC-DC converters which integrate power stage MOSFETs and a PWM controller using CMOS process have been used in many mobile applications. In this paper, we propose the calculation method of CMOS DC-DC converter efficiency and report optimum design of CMOS DC-DC converter based on this method. By this method, converter efficiencies are directly calculated from converter specifications, dimensions of power stage MOSFET and device parameters. Therefore, this method can be used for optimization of CMOS DC-DC converter design, such as dimensions of power stage MOSFET and switching frequency. The efficiency calculated by the proposed method agrees well with the experimental results.
It has been said that connecting MOSFETs in parallel makes power consumption reduce without concentrating current on one of MOSFETs easily, because the resistance of MOSFET have a positive temperature characteristic. But switching MOSFETs under low voltage and high current condition causes concentration of switching loss owing to unbalance of avalanche characteristics of MOSFETs and the concentration of switching loss leads a MOSFET to thermal destruction. In this paper, a novel gate drive circuit dividing the switching loss equally between MOSFETs connected in parallel is proposed. The surge energy at turn-off time is not consumed by the avalanche characteristic of MOSFETs, but by the channel resistance of the MOSFET, because the new circuit controls the gate voltage. The switching loss in the new circuit hardly increases compared to the conventional one, because its switches operate with a high-speed response.
We can see a lot of observation cameras at public or private facilities such as stations, halls, shopping malls, hallways and gates. Some janitors of the facilities want to detect and investigate passing people or congestion existences in the camera scene. In order to respond to these requests, we extracted moving areas in the image and accumulated these data and then displayed them on the monitor. Consequently, we obtained spatial distributions and hourly changes of congestion in the observation camera scene. To extract moving areas, we estimated the differences of correlation value of segmented small windows in the image. This paper describes our procedure to analyze the congestion from the image sequence of observation camera, and some experimental results.
The security is most important now because invader crime is recently increasing. Many countermeasures are used for the security of Building and Facilities. It is difficult to decide that such countermeasures are enough or not. Therefore, Rank-Matrix method is used for security evaluation. The method was used for security evaluation for complex systems.
This paper proposes an arc contact loss rate estimating method for Shinkansen trains with pantographs connected to bus cables. For the speedup of Shinkansen, it is necessary to judge whether the contact loss rate exceeds its standard value. As the standard of contact loss rate is provided from the viewpoint of contact strip wear caused by arcs, it is important to measure the amount of arc. The optical type contact loss measuring method which detects the contact loss by arcs is suitable for this purpose. It is difficult, however, to measure contact loss by this method in the daytime, because of the influence of outdoor light. To solve the above problem, we have developed an arc contact loss rate estimating method by using a contact loss simulation program on the basis of the complete contact loss rate measured by the current type contact loss measuring method which is effective in the daytime. Furthermore, we measured the contact loss rate simultaneously by the current and optical type contact loss measuring methods in the running tests of Shinkansen trains, and confirmed the validity of this estimation through a comparison of measured and simulated results.
The thermal magnetic material (TMM) is one of new materials, which the permeability is varied with the temperature change, and it is possible to use the TMM for the thermostatic switches. In order to analyze the dynamic characteristics of the thermostatic switches, we have to consider not only the magnetic field, but also the heat transfer and the motion of the armature, simultaneously. In this paper, a new method coupled with the magnetic field analysis, the heat transfer analysis and the motion equation is proposed by using the 3-D finite element method with edge elements. The validity of this method is verified through the comparison of the measured results. The usefulness of this method is confirmed by applying to the dynamic characteristics analysis of the thermostatic switch.