Recently, extensive research has been carried out on the preservation of human skill, a promising means of education and training. In the future, construction of motion database networks is required to preserve and utilize various skills. However, large-capacity data storage devices are required to save as many motion patterns as possible. Data compression methods based on signal processing are typically employed for data reduction. These methods, however, involve extensive and complex calculation and afford poor motion reproducibility. This paper presents a system for reducing motion data; this system has been designed without considering data compression methods. The proposed system is defined as a motion assembly system. During motion saving, the motion data measured by a master-slave system are saved and decomposed into a grasping mode and a manipulation mode. During motion reproduction, the data corresponding to the reproduced motion are generated by the assembly of the saved grasping and manipulation modes. Various motion patterns are reproduced by using some functional elements.
This paper proposes a new torque estimation method that takes into account the spatial harmonics of permanent magnet synchronous motors and that is capable of real-time estimation. First, the torque estimation equation of the proposed method is derived. In the method, the torque ripple of a motor can be estimated from the average of the torque calculated by the conventional method (cross product of the fluxlinkage and motor current) and the torque calculated from the electric input power to the motor. Next, the effectiveness of the proposed method is verified by simulations in which two kinds of motors with different components of torque ripple are considered. The simulation results show that the proposed method estimates the torque ripple more accurately than the conventional method. Further, the effectiveness of the proposed method is verified by performing on experiment. It is shown that the torque ripple is decreased by using the proposed method to the torque control.
This paper proposes a new method for the diagnosis of short circuit faults in the stator winding of a motor; the method involves gauging the probability of fault occurrence by considering feature distributions of a healthy motor. When a fault occurs, the current flowing into the motor increases, and the phase of the current leads that of the current in a healthy one. These characteristics of the current are valuable for fault diagnosis of motors. In this paper, first, we introduce the probability that can be used to detect a fault. Second, the average and standard deviation of both magnitudes and phases of the currents in several healthy motors are calculated. By using the calculated values and features observed in a target motor that is to be examined, the probability is computed. Finally, the usefulness of the proposed diagnosis method is verified through experiments involving the use of faulty motors.
This paper proposes a ZMP-compensation method based on pole-zero cancellation for biped robots. Conventionally, walking stabilization controls is achieved by using the feedback of ZMP error. In these systems, several feedback gains need to be determined, and this is done by using the optimal control theory or the pole-placement method. In the proposed method, only one feedback gain needs to be determined. Therefore, the proposed method makes it easy to design a walking stabilization controller. The effectiveness of the proposed method is confirmed from the results of simulations and experiments.
The synchronous mode is widely used in the start-up of a position sensorless PMSM drive system. However, the shock in speed and current may occur when the control mode is changed to the position sensorless control mode for a wide-range load. In this paper, a start-up method for a PMSM with position sensorless control is presented. To reduce the shock in speed and current when the control mode is changed, a method to adjust the vector angle of current reference in the synchronous mode is proposed. Using the method, the position error between the control axis and rotor axis can be reduced before the control mode is changed, and all of the PI controllers can be initialized properly. The effectiveness of the proposed method is verified by simulation and experimental results.
In this paper, coupled method for the dynamic characteristics of a 3-D electromagnetic spherical actuator under the open-loop control is proposed by the 3-D finite element method, in which the magnetic field equation is combined with equations of electric circuit and three-axes motions. The validity of the analysis is confirmed by comparing with the measured results of a prototype.
Grain-oriented electrical steels show a high degree of anisotropy that favors magnetization in the rolling direction. Magnetization also occurs in other directions in the joint regions that are characterized by interlaminar flux. For direct measurement of such flux behavior, flat sensor elements that do not create additional air gaps have been developed. The present study carried out on a model core. To determine the local flux around the joint rejoin, thin Cu film elements were vapor-deposited on both sides of individual laminates. Normal flux components were detected by frame coil arrangements, and in-plane components were determined by films with tip contacts through the coating. The obtained results showed that in the joint regions, the incoming in-plane flux is converted to interlaminar flux in the overlap region, until a high degree of global saturation is reached; at this stage the flux through the air gaps between the laminates leads to more homogeneous magnetization.
This paper describes the trajectory planning for the pushing motion of a humanoid robot. In the design of a humanoid robot for pushing an object, it is necessary to take into account many parameters such as stride length, pushing force, and walking velocity. However, there are no standard methods for evaluating these parameters. Additionally, the robot may fall down if these parameters are not chosen correctly. In this paper, a method for determining these parameters for pushing motion is proposed. The extended orbital energy (EOE) is considered as the design index. Here, the EOE describes the relation between walking motion and pushing motion. By using the proposed method, the COG trajectory, pushing force and stride length can be modified on the basis of the EOE. In other words, the suitable values of theses parameters can be obtained by determining only the desired EOE. As a result, the humanoid robot walks stably during pushing motion. The effectiveness of the proposed method was confirmed by experimental results.
The optical scanner is a scanning device in which a laser beam is reflected by a mirror that can be rotated or oscillated. In this paper, we propose a new 2D electromagnetic resonant optical scanner that employs electromagnets and leaf springs. Torque characteristics and resonance characteristics of the scanner are analyzed using the 3D finite element method. The validity of the analysis is shown by comparing the characteristics inferred from the analysis with the characteristics of the prototype. Further, 2D resonance is investigated by introducing a superimposed-frequency current in a single coil.
We carried out a psychological study involving physiological measurements. We used the VAS to research the feeling. The physiological factor measured was the oxy-Hb. It was found that an auditory stimulus of 70[dB] is more uncomfortable than auditory stimulus of 50[dB]. Furthermore, the decrease in oxy-Hb was greater for the auditory stimulus of 70[dB] as compared to the auditory stimulus of 50[dB]. This tendency was found in the center of the forehead (ch22-ch25). There was a difference between the brain activity for the auditory stimulus of 70[dB] and that for the auditory stimulus of 50[dB]. It was also found that the sound level affects the comfort level of humans. It is necessary to obtain additional details on the effects from physiological index to psychological index in a future study.
Single-phase three-stage boost rectifier is studied. This has two capacitors for pumping action in each positive and negative DC line, and so the output voltage is approximately equal to that of voltage-tripler rectifier. An only active power switching device also provides the necessary control over the current. The experimental results under the current-mode control confirm that the input current can almost be waveshaped sinusoidally with a near-unity power factor operating at higher values of the output voltage.
A practical ZCS-PWM active edge-resonant cell employing the parasitic oscillation-suppressed clamping diodes is presented in this letter. The improved active edge-resonant cell is quite effective for suppressing the surge voltages at the turn-off transitions of active power devices, thereby reduction of the voltage rating of the power devices and circuit components can be achieved. The practical effectiveness of the improved active edge-resonant cell is confirmed by the experiments on the newly-developed ZCS-PWM boost DC-DC converter, and furthermore its extended ZCS-PWM DC-DC converter topologies are originally proposed.
This paper proposes a new simple unified analysis about high-frequency torque ripples of permanent-magnet synchronous motors, which are originally caused by a super-injected high-frequency signal. The analysis shows components of the high-frequency torque ripples, a sufficient and necessary condition for attaining zero ripples, and so on. The analytical result leads directly to several torque-minimizing techniques, and verifies the effectiveness of the conventional torque-minimizing techniques in a unified manner.
Series-connected energy storage cells require cell equalizers in order to mitigate cell voltage imbalance. Conventional cell equalizers, however, consist of a number of switches or transformers that are considered not preferable in the viewpoint of circuit complexity and reliability. This paper proposes an equalization charger that consists of a single switch and passive components. Experimental performance tests showed that series-connected EDLCs could be charged up to the uniform voltage level by the proposed equalization charger though the initial voltages of the EDLCs were imbalanced.