The mobile robot must move without unacceptable rapid motion. To address this issue, in this paper, a preview controller with time based spline approach is proposed.Using the time based spline approach, it is also important to plan the adequate trajectory.Here an approach to trajectory planning which has the trajectory determination strategy by virtual manipulator is proposed.Numerical and experimental results are shown to confirm the proposed algorithm.
Magnetic bearing using pining force of a permanent magnet and a high-temperature superconductor has been developed. Additional permanent magnet is introduced to increase the levitation force of the magnetic bearing. In this hybrid magnetic bearing system, levitation force is mainly given by the repulsive force of the permanent magnets, and stability for the lateral direction is given by pining force of the superconductor. The experimental device is developed. A ring type superconductor and a bulk one are examined. Levitation characteristics of the hybrid magnetic bearing are measured. A bulk superconductor shows better characteristics both levitation and lateral stability than ring one. Levitation force of the hybrid system becomes about twice as large as that of the no-hybrid one. Although repulsive force of the permanent magnet decreases lateral stability of the system, its influence becomes small by choosing adequate position of the permanent magnets and the superconductor.
This paper proposes a new adaptive meshing technique for the analysis of rotating machines. The meshes of the rotor and the stator are combined by filling the gap between them with new elements. By taking the geometric periodicity and the symmetry of the machine into account the technique is effective in reducing the numerical error in the torque calculation due to mesh irregularities. The paper also describes a method which uses the smoothness of the nodal force distribution as a criteria for mesh refinement during the adaptive meshing. Some results using the method are presented.
This paper presents a fast calculation method for major electrical characteristics of Surface Permanent Magnet Vernier Machine; SPMVM. This method enables a parametric calculation of the characteristics from a set of specifications and thus brings rough values of the maximum performance with given conditions in a few seconds. A calculation flow is presented, followed by detailed explanations for the equations comprising the proposed method. Validity of the proposed method is confirmed by comparing the calculation results with numerical analyses and experiments. Results of case studies are set forth, which include comparison of the characteristics of the SPMVM with conventional permanent magnet machines. The case studies show that the PMVM has higher torque and efficiency, but poorer power factor, than the conventional permanent magnet machines.
This paper presents the loss analysis and reduction of Slotless Permanent Magnet Motors (SLPMM). The resistance and current at the inverter carrier frequency are introduced, by which loss generated by the high frequency current (carrier loss) can be separated from the total loss. The experimental studies using 200W, 3000min-1 SLPMM with halbach magnet array show the effective reduction of carrier loss. Finally, the experimental studies using the SLPMM with a series reactor proved the proposed loss analysis.
A permanent-magnet induction generator (PMIG) is a special induction machine self-excited from the inside of the squirrel-cage rotor by a permanent-magnet (PM) rotor. The PMIG can be made to operate as a stand-alone generator when the squirrel-cage rotor is driven by an external prime mover. Moreover, if the capacitors are connected across the stator terminals, adjusting their values can control the output voltage. This paper presents a method for predicting the steady-state performance of such a stand-alone PMIG theoretically. By introducing the per-unit system, a nonlinear equivalent circuit, which can include the variation of the circuit parameters, is derived. Based on this equivalent circuit, the steady-state performance is theoretically calculated, and its validity is confirmed through experiments.
This paper presents the current waveform control of a distributed generation system to suppress harmonic voltage and current on the distribution system. The proposed waveform is composed of the fundamental and harmonics components. The amplitude of each harmonic component is proportional to that of the terminal voltage and the phase is opposite. The characteristics of both the harmonic suppression effect on the distribution system and the capacity of the power converter are examined. The effectiveness of the proposed current waveform control has been verified by experiments.
Permanent Magnet Synchronous Motors (PMSM) are widely utilized today. Usually, they are designed so that they may induce the sinusoidal electro motive force(emf) because of necessity to suppress torque ripples when they have been driven by sinusoidal control currents. Thus, the measures for using the magnets are restricted. In this paper, a broadened magnet type interior PMSM which induce the non-sinusoidal emf is proposed. Maximizing of torque, minimizing of copper losses and torque rippleless are taken into considerationand the best suitable current form is calculated. Performance of IPMSM in this case compared with that of ordinal sinusoidal emf type IPMSM driven by sinusoidal current through the calculation. We found that the torque increased from 14.6% to 16.8% while width of magnet had been increased by 20.5%.
A photovoltaic power generation system based on immittance conversion theory is described. The name of an AC module stands for an integrated inverter installed on the backside of the PV module panel, and it generates about 100W of ac power. One distinctive feature of the proposed system the modules supply ac power as a current source to the utility line, and its output current is proportional only to the output voltage of the voltage source inverter on the AC module. The characteristics of the immittance conversion theory achieve this effect. Hence, it is not necessary to use current feedback control. The effectiveness of the proposed system is confirmed through simulation and experiment. The efficiency and THD of the inverter are 83%, 3.3%respectively when the output power is 88W.
This paper proposes a method to extract the position of a symmetric industrial component with respect to a point by template image matching. The template image is registered in the objective image and the target image area is searched in the same objective image using the inverted template image. The proposed method is robust to the inclination and the scale change of a component because the template image and the target image area are included in the same image. The experimental results show that the method is useful for measuring the positions of various components.
In this paper, a monitoring system for industrial robots working in factories is proposed. This system detects different movement from learning and immediately reports to the operator. It has the advantage that there is no need to receive any signal from the robot controller because it only observes with a simple camera such as a CCD camera. For the detection method, Eigenspace Method is used which is excellent in compression of image data and calculation of the correlation among images. Parametric Eigenspace Method is also used to detect abnormalities such as the speed of movement. Some experiments using 2-axis robot show the effectiveness of the proposed method.
This paper discusses a new control strategy for photovoltaic power generation systems with consideration of dynamic characteristics of the photovoltaic cells. The controller estimates internal currents of an equivalent circuit for the cells. This estimated, or the virtual current and the actual voltage of the cells are fed to a conventional Maximum-Power-Point-Tracking (MPPT) controller. Consequently, this MPPT controller still tracks the optimum point even though it is so designed that the seeking speed of the operating point is extremely high. This system may suit for applications, which are installed in rapidly changeable insolation and temperature-conditions e.g. automobiles, trains, and airplanes. The proposed method is verified by experiment with a combination of this estimating function and the modified Boehringer's MPPT algorithm.
This paper describes a personal cart for an elderly person and its control. The cart actively supports walking of an elderly person by himself/herself so that he/she can go out freely. The control system is synthesized to make the cart drive in accordance with gaits of an operator. The developed computer-controlled personal cart has four wheels and its controlling devices. The interval of its two front wheels is narrow, and the interval of the rear wheels is wide. Its structure looks like a three-wheeler. The two front wheels are driven by a DC-motor. An infrared radiation sensor measures the distance between the cart and the operator. The proposed system makes the cart maintain the distance between the personal cart and an operator at a certain level so that it can reduce the workload of the operator, who is walking on a slope with some baggage. It is not easy to describe the dynamic characteristics of the cart by a mathematical model, including its changing characteristics due to the driving environments such as the condition of roads and/or baggage. Furthermore, the cart system should be a human friendly system, because it is used by an elderly person. Therefore, the controller is synthesized based on a fuzzy theory. The proposed controller consists of two fuzzy controllers for driving and stopping the cart. The controller for stopping can stop the cart certainly as the cart does not access to the operator too much. The performances of the proposed system were tested in various conditions. Good performances of the control were also obtained independently of the condition of the road. Therefore, the proposed system is conceivable to be useful for the assisting of the walking.
Recent induction cooking apparatus are utilized for induction heating of ferromagnetic materials at 20-50kHz with a high efficiency. They can not, however, be applied for non-magnetic materials such as aluminum vessels. Here, we present a voltage-clamp reverse conducting ZCS high frequency inverter of half bridge type for induction heating of an aluminum vessel. The switching devices utilized for this inverter are SITs and its operating frequency is determined as 200kHz. This paper describes its circuit constitution and the obtained experimental results from a practical point of view.
This paper presents novel pole design with enlarged pole surface for the purpose of increase thrust/volume ratio without changing a gap length in a linear motor. Two pole designs are investigated by the finite element analysis and experiments. As a result, it is clear that the thrust increase about 7—20% compared with a conventional design, by using the arc pole design. And an normal force decrease about 25—50% compared with a conventional design.