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Home appliances such as residential air conditioners are based on the variable speed drives for AC motors such as IPMSM and IM. These variable speed drives always require the simple and low‐cost system configurations without the large electrolytic capacitors, reactors, and power devices that consist of PFC converters. This paper surveys and analyzes the proposed and advanced control techniques to achieve high input power factor and sinusoidal source current control in electrolytic capacitor‐less inverters. The investigated control methods consist of control algorithms based on the energy flow between input and output of the electrolytic capacitor‐less inverter, and all of them are useful as high‐power factor control methods for compressor drive motors such as air conditioners. Moreover, these techniques realize the variable speed drives for AC motors to meet power supply harmonics regulations (IEC61000‐3‐2). © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Industrial robots experience posture-dependent inertial variation and interference forces between joints, which in turn generates undesired vibrations due to the inherent elasticity of the reduction gears, making it difficult to control each axis independently. Conventionally, dynamic compensation is used to compensate the robot dynamics and decouple each axis, while state feedback control based on a two-inertia model is used for dealing with the vibrations caused by the elasticity of the reduction gears. However, the control design for this approach usually assumes a fixed moment of inertia, so its performance is compromised when large and fast changes in the robot posture occurs. In this paper, a posture-variant approach that takes into account the posture-dependent inertial variation in real time is proposed to achieve exact dynamic compensation and independent control of each axis regardless of the robot posture. The state equations of the posture-variant two-inertia system model for each robot axis are discretized using the finite-difference time-domain (FDTD) method and adapted on both the dynamic compensation and feedback control parts, allowing to easily redesign the whole control system considering the inertial variation at each control cycle. The effectiveness of the method is confirmed by experimental verification on a 6-axis industrial robot. [ABSTRACT FROM AUTHOR]

Flexible optical disks (FOD) have a feasibility of their high data-transfer rate and large capacity for archival storage. We have been developing the FOD in order to replace as the media with a current professional video cassette recorder (VCR) of HD-D5 format which have a data-transfer rate of more than 250 Mb/s. Here, we developed the FOD with the high recording sensitivity for high-speed recording, and succeeded to record the 252 Mb/s data with the high-speed tracking control method and optimized write strategy. We also employed the partial response maximum likelihood (PRML) read channel for playback data. We could get and achieve the low byte-error rate (BER) below 2 x [10.sup.-4] at the recording speed of 252 Mb/s, enough to record the video signals of HD-D5 VTR for professional broadcast use. Index Terms--Broadcast use, flexible optical disk, high-speed recording, PRML, 252 Mb/s, ZPET-FF control.

This paper proposes a novel control design for multilateral system considering different degrees of freedom (DOF) and structure. The conventional coordinate transformation with respect to the Cartesian coordinate system is not always suitable for bilateral and/or multilateral control for dexterous tasks, including grasping motion. This paper introduces spatial mode transformation, which is corresponding to human's tasks. The spatial modes are abstracted by using mode quarry matrices. The order of the mode quarry matrices means the task DOF, and the decoupled modes correspond to 'translational task,' 'rotating task,' 'grasping task,' and so on. Thus, the problems for motion integration of different DOF and structure are solved to design a multilateral controller in the spatial mode coordinate systems. Furthermore, the proposed multilateral control is designed based on acceleration control to realize both the force serving and the position regulator for action-reaction law in remote environment simultaneously. The proposed multilateral control is applied for a multimaster/single-slave system, where the DOF is different from each other. As a result, a complicated task for the slave system is easily realized by two master systems with vivid force feedback based on modal control design of the multilateral system. The experimental results show viability of the proposed method. Index Terms--Acceleration control, bilateral teleoperation, disturbance observer, haptics, interaction mode control, mode quarry matrix, motion control, multilateral control.

Recently, skill acquisition of experts has been a serious problem of the medical or production fields. This paper proposes a skill preservation system for the motion acquisition of human fingers. The proposed skill preservation system is composed of a master-slave system, and the control system is based on bilateral motion control. Since a touching motion is subject to the 'law of action and reaction,' it is possible to decompose force information into action force and reaction force by using a bilateral control. Furthermore, a human motion is acquired in decoupled modal space by using the quarry matrices. The decoupied modes correspond to 'translating,' 'rotating,' 'grasping' task motions, and so on. Thus, the skilled motion by a human is easily obtained in the modal space. The quarry matrices are also applied for temporal decomposition. As a result, modal and temporal analyses are realized by using the quarry matrices. The proposed skill preservation system is applied for grasping motion by three fingers. The experimental results show viability of the proposed method. Index Terms--Acceleration control, bilateral teleoperation, disturbance observer, force control, motion control, quarry matrix, real-world haptics, skill preservation.

The improvement of adhesion characteristics is important in electric commuter train. The electric commuter train has both a slip phenomenon and a slide phenomenon. Slip-and-slide phenomena degrade the comfortable riding performance of electric commuter train. We have already proposed an antislip/ antislide readhesion control system based on disturbance observer and sensorless vector control. The effectiveness of the proposed method has been confirmed by the experiment and the numerical simulation using the tested bogie system of electric commuter train. Then, we apply the proposed method to the actual electric commuter train of series 205-5000 of the East Japan Railway Company. In the experimental results of series 205-5000, this paper demonstrates that the proposed antislip/slide readhesion control system has the desired driving wheel torque response. Moreover, this paper discusses the evaluation method of readhesion control test results. Index Terms--Adhesion control, antislide control, antislip control, disturbance observer, railway, speed-sensorless vector control.

Motion control technology in an open environment will be more important. Future motion systems should interact with other systems or environments. To adapt to complicated environments and do tasks, a realization of multi-degree-of-freedom motion is necessary for human cooperating motion. This paper proposes a unified control approach for multirobot systems by interaction mode control. The proposed interaction mode control considers only interactions between systems. The interactions are abstracted by using mode quarry matrices. Since the transformed modes are independent of each other, it is possible to design a controller in decoupled modal space. This paper also proposes a novel control index named 'hybrid ratio.' Hybrid ratio is defined as the influence of external acceleration input on the acceleration response of a system. Since it is possible to realize the assigned hybrid ratio in each mode according to the task, the motion command with hybrid ratio is represented as task code. Thus, the interaction mode control is able to be treated as task kinematics. The proposed interaction mode control is applied for grasping motion by multirobot systems. The numerical and experimental results show the viability of the proposed method. Index Terms--Acceleration control, disturbance observer, haptics, hybrid control, interaction mode control, modal decomposition, motion control, multirobot systems.

In recent years, realization of a haptic system has been strongly desired in the fields of medical treatment and expert's skill acquisition. The bandwidth of force sensing and friction compensation are very important problems for reproduction of vivid force sensation. In this paper, an environment quarrier is proposed for bilateral teleoperation instead of force sensors. The environment quarrier is a novel force-sensing method that consists of a twin robot system. Two of the same type of robot are required and they are controlled in the same position, velocity, and acceleration by bilateral acceleration control based on a disturbance observer. One robot is in contact motion and the other is unconstrained. The purity of external force is obtained by subtracting the disturbance torque in the unconstrained robot from the constrained one. The environment quarrier can observe the external force with high bandwidth and friction compensation. In this paper, the idea of multilateral control is introduced for attainment of simultaneity. Furthermore, this paper shows the controller design of the multilateral control in the modal space. The experimental results show the viability of the proposed method. Index Terms--Acceleration control, bilateral teleoperation, disturbance observer, environment quarrier, force sensation, haptics, motion control, multilateral control.

This paper proposes a new robust tracking servo system for the optical disk recording system with feedforward controller based on the prediction of the tracking error. In optical recording systems, the feedback servo system must suppress the influence of force disturbance and parameter variation. To overcome this problem, this paper designs the robust feedback control system by using coprime factorization and disturbance observer. The detecting signal of the optical disk recording system is only a tracking error. Hence, the feedforward controller of the proposed tracking control system is constructed based on both the 'zero-phase-error tracking' control theory and the prediction of the tracking error. The experimental results point out that the proposed tracking servo system has a quick and precise tracking response and keeps the residual tracking error below its tolerance. Index Terms--Disturbance rejection, optical disk recording system, prediction of the tracking error, robust control, zero-phase-error tracking control.

Generally, a speed servo system of a vector-controlled induction motor has limitations of motor voltage and current. When the speed servo system has a large torque reference, the output of its PI controller is often saturated. In this case, the conventional servo system stops the integral calculation of its PI controller. However, this system often has a large overshoot and/or an oscillated response caused by both a windup phenomenon and phase error on the vector control condition. This paper proposes a new speed servo system considering voltage saturation for the vector-controlled induction motor. The proposed control method compensates the phase error on vector control condition quickly, and always keeps the vector control condition. The experimental results show that the proposed system well regulates the motor speed and the secondary magnetic flux for a large torque reference without a windup phenomenon. Index Terms--Antiwindup algorithm, output saturation, speed servo system.