In teleoperation, human operator manipulates a master robot while watching a video image which is sent from remote environment. If ideal bilateral control is realized in teleoperation, human operator can sense impedance of environment. This information will prevent from breaking remote environment and human operator can achieve more dexterous tasks. However, the presence of network delays between a master robot and a slave robot makes the design of this system challengeable. One of the concerns is the synchronization with haptic and visual sense. This paper proposes a bilateral control system to synchronize haptic and visual sense. For realizing this control target, the round trip time delayed master force is utilized. In the proposed control system, the position response of the master robot synchronizes with the visual image of the slave robot. The validity is confirmed by numerical analysis and experimental results.
In this paper, the singular configuration problem of a wheel-legged mobile robot due to the rank deficiency in inverse kinematics is discussed. Rank deficiency occurs when multiple kinematic constraints conflict with each other or when the steering joint becomes perpendicular to the ground surface. A method was proposed for avoiding a singular configuration while simultaneously solving the constraints that uses inverse kinematics that considers priority and solves the singular configuration of the steering joint using kinematic constraints on acceleration. Consequently, a new singular configuration occurs in low-speed wheeled locomotion. The Levenberg-Marquardt method is used for the singular configuration in low-speed wheeled locomotion. This method is necessary for determining a suitable damping factor, because it affects the solution of the inverse kinematics. Therefore, a comparison of different damping factor determination methods and a proposed method that considers the steering motion of each leg are highlighted.
A zone-control induction heating (ZCIH) system heats workpieces using several induction coils. To design and control the ZCIH system, parameters such as the self/mutual inductance and self/mutual-equivalent resistance between coils should be obtained in advance. For this purpose, we have proposed a practical method called “multiport transformer model” to reduce the computation time in calculating these parameters. In this study, we compare the parametric result obtained by simulations using the multiport transformer model, with the result obtained through the finite element method (FEM) analysis results and experimental data to validate the computational accuracy of the multiport transformer model. The comparison result shows that the characteristics of the inductance and equivalent resistance calculated by the multiport transformer model are similar to those obtained from the FEM analysis and experimental result. This indicates that our proposed model can contribute to the design optimization and control of a ZCIH system.
In this study, we investigated bilateral control in the vertical direction using functional electrical stimulation (FES). Bilateral control is a remote operation technique that incorporates force feedback. This technology has potential applications in everyday life, including allowing medical doctors to make diagnoses or friends to communicate using tactile sensations when far apart. However, current iterations of this technology require robot arms to be worn. This is undesirable as such arms are heavy, and arms with multi degree-of-freedom are difficult to produce. To address these problems, we investigated bilateral control using FES. However, in previous studies, which applied FES to bilateral control, control in the vertical direction and the effect of reaction forces were not investigated. In this study, we verified that vertical control is achievable. First, the movements of a human operator were shown to follow those of another operator in the vertical direction, demonstrating that vertical bilateral control using FES is effective. We next investigated whether an operator could recognize when the partner was holding a weight. This experiment demonstrated that the operator was able to recognize the presence or absence of the weight in the hand of the partner. However, shaking was observed in the arms of the master and slave. We believe that this problem can be eliminated by estimating the reaction forces of arms.
This article deals with a compensation performance of harmonic currents with constant dc-capacitor voltage control of the previously proposed smart charger for electric vehicles (EVs) in single-phase three-wire distribution feeders. The instantaneous power flowing into the smart charger shows that balanced and sinusoidal source currents with a unity power factor are obtained on the secondary side of the pole-mounted distribution transformer. Digital computer simulation results with PSIM software demonstrate that balanced and sinusoidal source currents with a unity power factor are obtained during the battery charging operations in EVs, compensating harmonic, fundamental-reactive, and unbalanced-active currents.