The segment stator core, high space factor coil, and high efficiency magnet are indispensable technologies in the development of compact and a high efficiency motors. But adoption of the segment stator core and high space factor coil has not progressed in the field of outer rotor type motors, for the reason that the inner components cannot be laser welded together. Therefore, we have examined a segment stator core combination technology for the purposes of getting a large increase in efficiency and realizing miniaturization. We have also developed a characteristic estimation method which provides the most suitable performance for segment stator core motors.
This paper proposes new practical optimal current control methods for a newly emerging class of non-salient pole synchronous motors with hybrid rotor fields by both permanent magnet and winding. In practical situation with limited voltage, the extensively used permanent magnet synchronous motor hardly achieves an ideal performance that allows simultaneously both low-speed high-torque and wide speed-range operations, due to its constant magnet field. The hybrid field synchronous motors (HFSM) are recently emerging to achieve the ideal performance as practical motors with controllable hybrid rotor field. For HFSM, the same torque can be produced by a variety of currents due to nonlinearity between torque and currents. Consequently, appropriate determination of a set of stator and rotor current commands plays a key role to achieve possible energy-efficient and wide speed-range operation. Proposed methods determine the current commands corresponding to a given torque command such that total winding copper loss due to stator and rotor currents can be minimized if the exact solution exists, the best approximate torque can be produced if no exact solution exists. The determined current commands are the optimal in sense of energy-efficiency or degree of approximation in wide speed-range operation under voltage limit. New real-time recursive algorithms searching the optimal current solution are also given. The proposed methods are analytical but practical, whose usefulness is verified through experiments.
This paper discusses about step planning of a biped robot in an environment with obstacles. Biped robot has a mechanical advantage to work in human surroundings. This is accomplished by its capability to select the discrete contact point with the ground. Though its foot placement should be discussed to step over obstacles, it is difficult because dynamic biped locomotion is a complex interaction system between upper body motion and stepping point. Applying the idea of virtual supporting point, this complex interaction is solved. The collision detection is easily achieved through modeling the obstacles to an off-limits on the horizontal plane. A stamp area is set in order to avoid the extreme stride alteration. Through these methods, the robot can prepare for the obstacle beforehand and select a series of footsteps that provides stable locomotion. Experimental results are shown to confirm the validity of the proposed methods.
Bearingless switched reluctance motors, which can control rotor radial positions with magnetic force, have been proposed. The bearingless switched reluctance motors are characterized by integration of switched reluctance motors and magnetic bearings. These motors have two kinds of stator windings composed of motor main windings and suspension windings in the same stator in order to produce suspension force that can realize rotor shaft suspension without mechanical contacts or lubrication. For successful stable operation, accurate theoretical formulae of instantaneous torque and suspension force are necessary to a rotational speed controller and a rotor radial position controller. This paper derives the theoretical formulae of the instantaneous torque and the suspension force from an assumption of simple permeance distribution. This derivation process makes an assumption that fringing fluxes are distributed on elliptical lines. It is shown with experimental results that the derived theoretical formulae are very accurate in terms of practical application.
It is important to discuss the behavior of traffic at merging sections in the design of the overall Automated Guided Vehicle System (AGVS) and in the realization of the system. In this paper, we deal with a merging section of the AGVS under time limit for merging. Near the merging section, one flow of traffic must form a queue to avoid collision of vehicles. We propose an improved control strategy and clarify the fundamental features comparing with previous model. It is analyzed that the vehicle behavior at the merging section of the AGVS using the recurrence relation. The analytical solutions have been obtained.
This paper presents a novel lightweight linear actuator using permanent magnets and having its coils on the stator concentratedly. The rated force is 6N, the stroke is 30mm, and the weight is below 300g owing to its unique structure. The machine is to be applied to e.g. a pick-and-place actuator of tiny electronic parts, and the performance for the application is confirmed through experiments with a prototype.
Permanent magnet type linear synchronous motor (PM-LSM) that is utilized for the discontinuous primary has been proposed to satisfy the requirements include the speeding up the transportation system and simplifying the maintenance as a result, synchronization and a positioning method are established. However, velocity pulsation of the secondary occurs when the secondary mover overlaps with the primary section. This paper describes the examination of constant load angle control without position feedback with the aim to suppress the velocity pulsation, which happens in the re-acceleration part.
This paper presents an initial rotor position estimation of Half-Wave Rectified Brushless Synchronous Motor. In the previous paper, we proposed this motor as AC servo motor, which is based on the half-wave rectified brushless excitation principle. The basic principle of this estimation technique utilizes the dependence of inductance on the rotor position. The bias frequency component of half-Wave rectified brushless excitation is used to estimate the rotor position error. The magnetic pole is discriminated by the switching condition of the diode inserted into the rotor field winding. This estimation technique is confirmed by simulation include inverter circuit, control program and motor model. Finally, the effectiveness of the proposed estimation technique has been verified by experiments.
An indoor 4-wheel individual steering and driving vehicle with full electronics was built for evaluating the system ability and the performance in practical use. Mechanical parts such as the connecting rod and the differential gear are not provided for this vehicle. From trial operation, the characteristics are fully performed as in design, but some problems that originated from the design concept are disclosed. Rotating radius (R) of the vehicle was taken for steering command parameter, but it was found that it is not an appropriate parameter for driving operation. The reasons are as follows; 1) R has much different sense of driving conformability for the driver, because it doesn’t refer to the running direction, but to the rotating radius of crosswise direction. 2) Sensitivity of each wheel steering angle against R differs over double figures in full range of R. 3) R changed from plus to minus and also the other way in most practical situations around go-straight operation. For these reasons, the steering command parameter was changed from R to α, where α is the angle between vehicle lengthwise direction and the moving direction. The steering control algorithm using α parameter has been proven to solve the above mentioned problems 1), 2), and 3).
This paper presents a novel Genetic Algorithm (GA)-based autonomous compensator design and position command shaping considering the stand vibration suppression for the fast-response and high-precision positioning of mechatronic systems. The positioning system is mainly composed of a robust 2-degrees-of-freedom (2DOF) controller based on the coprime factorization description. The feedback compensator based on H∞ design framework in the 2DOF controller ensures the robustness against the variations of resonant vibration mode. The feedforward compensator and position command, on the other hand, can be autonomously designed by the optimization capability of GA, in order to achieve the desired positioning performance and to suppress the machine stand vibration. The effectiveness of the proposed optimal design has been verified by experiments using a table drive system with ball screw.
The paper describes an approach for applying advanced image differential operation, for purposing to realize the visual servo system based on the advanced image processing. The conventional and ordinary visual servo system, in general, has employed binarized image processing approach, and/or preferred the simple operators so as to suppress the image processing time. On the other hand, the precise object recognition system has introduced the advanced image processing operators and filters which require much more processing time. In this paper, a novel advanced image differential operator based on the discrete Deriche filter has been proposed, and the high-speed differential operator has been implemented on hardware processing. The performance of the system should be determined by the sampling time of the visual servo controller and the required accuracy, so that the proposed system has been examined in several experiments, and furthermore applied to the visual servo system. Consequently, the validity of the proposed approach is confirmed in the experimental results on the visual servo system.
This paper deals with harmonic voltage detection methods for a shunt active filter intended for installation on a power distribution system. The active filter acts as a resistor to damp out harmonic propagation throughout the power distribution system. However, the active filter may fall into an unstable condition, because the control system forms a complex feedback loop including harmonic detection, current control, and system impedance. Stability and harmonic-damping performance of two different harmonic detection methods, that are comprehensive harmonic detection and specific harmonic detection, are compared with each other. Moreover, a new compensation scheme for the comprehensive harmonic detection method is proposed to improve system stability.
Over the past years, a great deal of studies have been devoted to electrical bicycle, electrical vehicle, and so on. In previous work, we studied a new d-c compound motor which is suitable for the electronic bicycle on the level ground. In contrast to this, this paper considers the performance evaluation of the new high-efficiency motor for an electrical bicycle in detail. We try to show the experimental results of several driving condition. This directly leads us to the conclusion that a new d-c compound motor is higher efficiency than conventional one.
This paper proposes a new high performance space voltage vector controlled inverter for speed servo system of induction motor. The proposed system carries out a fine anti-windup control on voltage saturation for vector controlled induction motor. The effectiveness of proposed method is verified by the experimental results.