Takafumi Koseki

Precise Speed Estimation From a Low-Resolution Encoder by Dual-Sampling-Rate Observer

This paper describes an effective way to estimate state variables, such as motor speed and disturbance from a low-resolution encoder at low speed by using the dual-sampling-rate observer. The dual-sampling-rate observer estimates the state variables at every DSP control period and correct the estimation error at the instant that the measurement signal is detected. A novel pole assignment method, which considers the relation of the estimation and error correction periods, is proposed to maintain the stability for long error correcting period. Moreover, the dual-sampling-rate observer can be applied for higher order systems since it is generalized in state space. The effectiveness of the observer is verified through various simulations and experiments

Comparing Approaches for Actuator Redundancy Resolution in Biarticularly-Actuated Robot Arms

Biarticular actuators-actuators spanning two joints-play a fundamental role in robot arm designs based on the human musculoskeletal actuation structure. Unlike kinematic redundancy, actuator redundancy resulting from biarticular actuation brings advantages such as increased stability, reduced link inertia, and decreased nonlinearity of the end-effector force with respect to the force direction. The way the actuator redundancy is resolved is a fundamental problem, as it strongly characterizes robot arms performance. In this study, the six most significant actuation redundancy resolution approaches in the literature-1-norm, 2-norm, infinity-norm, phase different control (PDC), nonlinear hase different control (NLPDC), and linear programming (LP)-are analyzed with respect to their design, and experimentally compared with each other using BiWi, a biarticularly actuated and wire-driven robot arm. In addition, an integrated control framework to resolve actuator redundancy maximizing end-effector force and simultaneously minimizing the necessary input torques is proposed.

Transverse-Flux-Type Cylindrical Linear Synchronous Motor Using Generic Armature Cores for Rotary Machinery

This paper presents the design and analysis of a transverse-flux-type cylindrical linear synchronous motor using generic armature cores for rotary machinery that can address the problem of complex structures in conventional transverse-fluxtype topologies. First, the operational principle and structural advantages of the proposed model are explained. The thrust density and cogging force are investigated during the initial design stage using an application in which large thrust density and low cogging force are required. The proposed model is both theoretically and numerically designed by using a magnetic-circuit method and a 3-D finite-element method, respectively. Finally, the results and efficacy of our structural concept are experimentally validated.

Anti-slip/skid Re-adhesion Control Based on Disturbance Observer Considering Bogie Vibration

This paper proposes a new anti-slip/skid re-adhesion control system for electric commuter train driven by inverter-fed induction motors. This paper designs an instantaneous tangential force estimator between driving wheel and rail, which is based on disturbance observer. The torque command of proposed system regulates to exceed this estimated tangential force in order to avoid undesirable slip phenomenon of driving wheels. For the actual bogie of electric commuter train, we have already proposed the anti-slip/skid re-adhesion control system based on the ordinary disturbance observer and the speed sensor-less vector control. This system has the fine torque response for slip condition. However, this system does not consider the vibration phenomenon of actual bogie dynamics of electric commuter train. In order to extend the anti-slip/skid re-adhesion control to the actual bogie system considering the vibration phenomenon, this paper proposes a new anti-slip/skid re-adhesion control based on a new high order disturbance observer considering the first resonant frequency. The numerical simulation results confirm the validity of the proposed control system.

Technical trends of railway traction in the world

This paper summarizes recent trends of electric traction technologies based on power electronics. Continuous electric power collection played a substantial role in rapid growth of commercial service of electric railways in the early 20th century. AC traction as an achievement of power electronics after 1980s contributes to the present efficient high-speed mass transportation service. Regenerative brakes and consequent power management using power converters and electric energy storages enhance ecological advantages of rail-guided transportation.

Control of a straight line motion for a two-link robot arm using coordinate transform of bi-articular simultaneous drive

There are some difference between biological subjects and conventional humanoid robots from the point of its mechanisms, control method, and application of the biological characteristics to humanoid robots are now being popular. Motion control for 2-link robot arm on specific condition are mainly discussed in this paper. From the point of mechanism, biological subjects have two joints simultaneous drive. Though benefits and characteristics of the mechanism on static condition have already cleared from the measurement of previous research, it has been calculated and discussed mathematically in this paper. In addition, dynamic motion control of a specific condition has been also calculated and considered. Furthermore, designing of each actuator torque which is based on the Electromiogram result and its control for external force on the tip point is concretely described. Finally, those characteristics of static and dynamic motions with bi-articular simultaneous drive on specific condition are summarized.

Anti-slip Readhesion Control of Electric Commuter Train Based on Disturbance Observer Considering Bogie Dynamics

This paper proposes a new anti-slip readhesion control system for electric railway vehicle driven by inverter-fed induction motors. This paper designs an instantaneous tangential force coefficient estimator between driving wheel and rail, which is based on disturbance observer. The torque command of proposed system regulates to exceed this estimated tangential force coefficient in order to avoid undesirable slip phenomenon of driving wheels. For the actual bogie of electric commuter train, we have already proposed the anti-slip readhesion control system based on the ordinary disturbance observer and the speed sensor-less vector control. This system has the fine torque response for slip condition. However, this system cannot consider the vibration phenomenon of actual bogie dynamics of electric commuter train. In order to extend the anti-slip readhesion control to the actual bogie system considering the vibration phenomenon, this paper proposes a new anti-slip readhesion control based on a new high order disturbance observer considering the first resonant frequency. The experimental results and the numerical simulation results confirm the validity of the proposed control system

Investigation of secondary slot pitches of a cage-type linear induction motor

Experimental and numerical studies are conducted on linear induction motors with cage-type rails in an effort to improve their motor characteristics in order to facilitate application of these motors to a new underground freight transport system. The framework of the study, based on the electric vector-potential formulation, is a visual representation of the secondary eddy-current path, as well as gap-flux distribution for assisting the motor designer. >

Superconducting Power Cable Application in DC Electric Railway Systems

A superconducting power cable is a prospective application of high-temperature superconductors. Although power cables using Bi2223 or YBCO wires have been developed in the world so far mainly for utility grid application, we focus attention on railway application of a superconducting power cable. We have studied how to introduce superconducting power cables effectively and economically to a dc electric railway. Numerical analysis models based on the MATLAB-Simulink are constructed for a dc electric feeder system of singe- and double-track railways. Tractive force and train resistance characteristics are modeled. Energy saving by the superconducting power cable is investigated with the influences of the number of substations, the train operation interval, etc., taken into account. The results show that the superconducting power cables can improve regeneration rate and system energy saving, and reduce the substation capacity very effectively. It will be also an advantage that if the transportation capacity of a railway line needs to be increased, the introduction of superconducting cables could achieve it without changing the existing substations along the line.

Energy-saving train scheduling diagram for automatically operated electric railway

Abstract Interest in energy-saving railway scheduling and operations is growing because of environmental concerns. Saving energy on both the hardware and software sides is an ever-increasing interest and challenge. Railway scheduling is closely related to the energy consumption of rolling stock. Energy consumption decreases when running time is increased because running curves can include considerable coasting time. However, the running time between two adjacent stations is determined for scheduling, and this running time is adhered to very strictly in Japan. Power-limiting brakes, which use regenerative braking without mechanical braking, are very useful in energy-saving operations. However, power-limiting brakes have some drawbacks, such as slow deceleration and the difficulty of notch operation. How to use power-limiting brakes effectively on schedule remains a research problem. We propose a method for developing an energy-saving schedule based on automatic train operation (ATO), which offers exceptional control notch performance and is easier to apply to an optimised schedule than manual train operation. In the proposed method, running time distribution is optimised based on energy savings between stations by keeping the total running time constant. Only the running time is optimised, so that additional timetabling strategies for energy-saving can be applied, such as reducing dwell and turnaround times and increasing running time margins. Practical considerations are included, such as determination of running times as integer values. The results of this study show that energy-saving efficiency is increased when the running time distribution between stations is optimised.