This paper proposes a novel control scheme for wide-speed-range operation of synchronous reluctance motors. The proposed scheme is a combination of maximum torque per ampere control, maximum torque per flux control, flux-weakening control, and torque limiting. These controls are based on a mathematical model in a rotating reference frame that is synchronized with the stator flux-linkage vector. The proposed control scheme is suitable for direct torque control or flux-oriented control. The validity of the control scheme is verified by the experimental results. Influences of parameter variation on the proposed control scheme are discussed. The proposed schemes of flux weakening and torque limiting are insensitive to parameter variation.
In this paper, a torque control method for permanent magnet synchronous motors (PMSMs) functioning in the middle speed range of the field weakening control region is proposed. The current resonance due to d axis and q axis coupling cannot be neglected. The current resonance is depressed by the appropriate design of PID controller for the q-axis current. The proposed controller designing method is verified both numerically and experimentally. The influence of parameter changes is also examined to reveal that the Lq change affect the torque performance more than Lq and Rm does.
Recently, real-world haptics which deals with real-world tactile sense has been actively researched. In real-world haptics, tactile information is extracted by a disturbance observer. In other words, tactile information is dealt with by an actuator as a disturbance force. Therefore, the disturbance of an actuator has to be minimized for the extraction of clearer tactile information and for the improvement of operationality. The identification and compensation of actuator's disturbance are necessary for improvement of operationality. However, in general, it is difficult to identify the disturbance because the disturbance has nonlinearity such as friction. In addition, the low accuracy of identification induces an overcompensation to the actuator. In this paper, the method of improving operationality using optimization problem is proposed. A constraint optimization problem is constructed for the disturbance identification and compensation without overcompensation. The optimization problem is solved by a conjugate-direction method which involves an algorithm of nonlinear optimization. In addition, the proposed method can determine the parameter values of disturbance using only 10s examination and automatic off-line processing. Therefore, considerable time and effort are not needed in the proposed method. The effectiveness of the proposed method is confirmed by experimental results.
This paper proposes a new design method for obtaining walking parameters for a 3-D biped robot walking along a step. Many researchers concentrated only on the motion of climbing up or down stairs. However, this study investigates a strategy for realizing walking along a step. In conventional methods, the center of mass (CoM) moves up or down during walking in this situation because the pendulum height is kept at the same length for the left and right legs. Thus, extra work is required in order to bring the CoM up to higher ground. In this study, different pendulum heights are applied for the left and right legs and this method is referred to as the dual length linear inverted pendulum method (DLLIPM). However, when different pendulum heights are applied, it is quite difficult to obtain symmetrical and smooth pendulum motions. Furthermore, synchronization between the sagittal and lateral planes is not confirmed. Therefore, DLLIPM with the Newton-Raphson algorithm is proposed to solve these problems. The walking pattern for both planes is designed systematically, and synchronization between the planes is ensured. Finally, the proposed method is verified by simulation and experimental results.