The motion control paradigm provides sufficient performance in many elementary industrial tasks. However, only stiff motion the robot cannot accommodate the interaction force under constrained motion. In such situation, the robot is required to perform interaction behavior with the environment. The conventional impedance control schemes require force-sensing devices to feedback force signals to the controllers. The force-sensing device is therefore indispensable and the performance of the system also depends on the quality of this device. This paper proposes a novel strategy for force sensor-less impedance control using disturbance observer and dynamic model of the robot to estimate the external force. In motion task, the robust D-PD (derivative-PD) control is used with feedforward inverse-dynamic torque compensation to ensure robustness and high-speed response with flexible joint model. When robot is in contact with environment, the proposed force sensor-less scheme impedance control with inner-loop D-PD control is utilized. D-PD control uses both position and speed as the references to implement the damping and stiffness characteristic of the virtual impedance model. In addition, the gravity and friction force-feedback compensation is computed by the same dynamic model, which is used in external force estimation. The flexible-joint robot model is utilized in both disturbance observer and motion control design. The workspace impedance control for robot interaction with human operator is implemented on the experimental setup three-degree-of-freedom (3-DOF) robot manipulator to assure the ability and performance of the proposed force sensor-less scheme for flexible-joint industrial robot.

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This paper proposes a new power converter without any switching operation, which works as a linear amplifier. The main circuit of the proposed converter consists of series-connected MOSFETs, series-multi dc power supplies and clamping diodes. The circuit configuration is similar to a diode-clamped multi-level inverter, except for using complementary power devices, which are n- and p-channel MOSFETs. One of the series-connected MOSFETs operates in an active state just like a linear amplifier, while the other MOSFETs operate in on or off states like an inverter circuit. As a result, the proposed converter achieves an acceptable efficiency as high as 90% without any ripples nor harmonics caused by switching operation. Experimental results demonstrate that the proposed converter has capability of driving a 2.2-kW three-phase induction motor.

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A new electromagnetic force analyzing method in end-winding is provided and evaluated by comparing to 3D- FEM electromagnetic analysis. Additionally, estimating method of end-winding vibration on load is suggested by measured data at factory test. Moreover, evaluating method for insulation degradation after operation is offered for large capacity cylindrical synchronous machines, where end-winding portion is the longest and electromagnetic forces on it is the greatest of all rotating machinery.

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The MAGLEV (magnetically levitated vehicle) is now well along in development testing at Yamanashi Test Line. The MAGLEV power source needs to supply a variable voltage and variable frequency to propulsion coils, which installed on outdoor guideway. The output voltage of the electric power converter contains many higher harmonics, which causes many troubles such as inductive interference. Accordingly, it is necessary to clarify the frequency characteristics of the propulsion coils and the power feeding circuit. In view of this situation, experiments and the theoretical analysis concerning the frequency characteristics of the propulsion coils with single-layer arrangement and the power feeding circuit at Miyazaki Test Line had been performed by the author. But the arrangement of the propulsion coils had been changed in Yamanashi Test Line from the single-layered coils to the double-layered coils for the stability of the super-conducting magnet on board. Thus, experiments and investigations concerning the frequency characteristics(resonance characteristics)of the propulsion coils with double-layer arrangement at Yamanashi Test Line have been performed but a theoretical analysis had not been done enough. A theoretical analysis was therefore done in this paper by applying the inverted L equivalent circuit with mutual inductance and capacitance to the propulsion coil, from which the positive and zero phase characteristics of the double-layered propulsion coils were analyzed.

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This paper presents an AC-AC power converter integrated with techniques that provide environmental harmony. The voltage source PWM inverter has been established as the major motor drive equipment. However, it is associated with issues pertaining to PWM switching as well as issues related to the input harmonics caused by capacitor input type rectification. Hence, there is need for a converter that addresses these problems and provides an environmentally harmonious solution. The matrix converter has a topology that inherently exhibits sinusoidal input current waveforms and less stressful output voltage waveforms. Combining the matrix converter with certain filter topologies is shown to provide an environmentally harmonious solution.

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It is well-known that one of the major limitations to achieve a good performance in mechanical systems is the presence of friction. High resolution positioning systems operating with accuracies in nanometer region usually exhibit relatively large steady-state tracking errors or even oscillations if controllers are designed without considering friction. Consequently, this paper aims at improving the position control of a high precision stage using a synchronous piezoelectric device driver (SPIDER) by comparing the performances of three friction compensators. These friction compensators detect friction in the system and use this information to modify the control input. The first using bang-bang control is based on the well-known static friction model. The second is a friction state observer based on the dynamic friction LuGre model, and the third is a feed-forward compensator based on the LuGre model. In order to effect a fair comparison, three friction compensators uses the same identified friction parameters in controller synthesis. The performance comparisons are presented by means of experimental results on the proposed high precision stage using SPIDER.

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This paper describes an optimal off-line tuning method for position controller in mechanical system using a new evolutionary algorithm called particle swarm optimization (PSO). Generally in the industry machinery, the autonomous performance to the position control system is getting more strongly demanded. In this paper, two approaches to the optimization are detailed. First, PSO is used in order to optimize the coefficient of a mathematical model as system identification. Second, the parameter of a controller will be directly optimized by evaluating a response using PSO. The proposed approach had superior features, including easy implementation, stable convergence characteristic, and good efficiency.

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In a motor with a stator which is inserted in a frame by shrink fit, iron loss increases and the increase has become a serious problem. Therefore, the stator shape has been studied to decrease the compression stress. In this paper, a new approach to decrease the loss is proposed, which makes use of physical properties of electrical steel sheet for tension stress, and new stator shape is shown and evaluated by experimental results to decrease the iron loss caused by the shrink fit.

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The authors have already proposed a passive EMI filter that does require access to the motor-neutral point. The EMI filter has been applied to an induction motor driven by a voltage-source PWM inverter with a three-phase diode rectifier used as the front end. Experimental results have shown that the EMI filter can mitigate leakage currents flowing out of the motor and the heat sink, as well as bearing currents circulating inside the motor. This paper deals with a passive EMI filter for preventing high-frequency leakage currents from flowing through the heat sink of a voltage-source PWM inverter together with a voltage-source PWM rectifier used as the front end. Both rectifier and inverter have the same carrier frequency as 14kHz. The tested motor equipped with the motor-neutral line is an interior permanent magnet synchronous motor (IPM-SM) rated at 190V, 5.5kW, 6 poles and 1,800rpm. This paper designs, constructs and tests two types of EMI filters. These filters consist mainly of two 10-mH identical common-mode inductors that are installed on the ac sides of the rectifier and the inverter, respectively. However, the two filters are slightly different in that one accesses to the dc-link mid-point, and the other does not access to it. Experimental waveforms verify that the former is superior to the latter in eliminating the high-frequency leakage currents from both the heat sink and the motor.

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It is very important to guarantee the quality of the industrial products by means of visual inspection. In order to reduce the soldering defect of terminal deformation and terminal burr in the manufacturing process, this paper proposes a 3D visual inspection system based on a stereo vision with single camera.
It is technically noted that the base line of this single camera stereo was precisely calibrated by the image processing procedure. Also to extraction of the measuring point coordinates for computing disparity, the error is reduced with original algorithm. Comparing its performance with that of human inspection using industrial microscope, the proposed 3D inspection could be an alternative both in precision and in processing cost. Since the practical specification in 3D precision is less than 0.02 mm and the experimental performance was around the same, it was demonstrated by the proposed system that the soldering defect with terminal deformation and terminal burr in inspection, especially in 3D inspection, was decreased.
In order to realize the inline inspection, this paper will suggest how the human inspection of the products could be modeled and be implemented by the computer system especially in manufacturing process.

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In this paper, we investigate losses of interior permanent magnet motors driven by PWM inverters using 3-D finite element analysis, which can estimate the eddy current loss in the permanent magnet accurately. The calculated losses are compared with the measured results and the theoretical solution to verify the validity of the analysis. The method to decompose the electromagnetic field distribution into time-harmonic components is introduced in order to investigate the effects of the harmonic fields separately and to specify the main loss factors. The variation of the magnet eddy current loss due to the division of the magnet is also investigated. It is clarified that the magnet eddy current loss of the magnet depends on the voltage modulation ratio of the inverter and the magnetic saturation of the core. It can be said that the thickness of the divided magnet should be smaller than the skin depth of the eddy currents produced by the major harmonics for the loss reduction.

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This paper examines the cogging torque of a permanent magnet (PM) motor resulting from the asymmetry property of magnetic poles, which comes from the performance variation between magnets. A PM motor with 32 poles (= 16 pole pairs) and 36 slots is selected for verification, because the motor whose pole/slot ratio is 8/9 is sensitive to the performance variation between permanent magnets. Assuming that two different magnetization levels of magnets are mixed together in one rotor, the amplitude of the 2.25th and 4.5th components of cogging torque, which show 36 (=2.25 × 16) and 72 (=4.5 × 16) times of pulsation per rotation respectively and both of which result from the asymmetry property of the magnetic poles, are evaluated. As a result, it was clarified that the cogging torque characteristics depend upon the alignment pattern of the two kinds of magnets. The amplitudes of the 2.25th and 4.5th components of cogging torque are proportional respectively to the amplitude of the 36th and 72nd components of the squared magnetic flux density around the rotor which is set in the space. Using the proportional constants found from the finite element analyses in some alignment patterns, the cogging torque amplitudes of the motors with other alignment patterns can be predicted only by calculating the squared magnetic flux density around the rotor. The predicted cogging torque amplitudes correspond to the actually calculated results.

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