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Shinji Doki - IEEE Xplore Author Profile

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We propose a novel pan-tilt-zoom (PTZ) camera configuration planning method to improve data collection for structure visual inspections. This method plans a set of configurations for PTZ camera-equipped robots to collect visual data of target surfaces at the required spatial resolution. Unlike previous methods that focus solely on optimizing camera positions to cover different areas of the target,...Show More
We propose a viewpoint generation algorithm for the visual inspection of civil engineering structures using robots equipped with a gimbal-mounted camera. This algorithm enables robots to completely inspect target surfaces at the required spatial resolution while reducing movement by effectively utilizing the gimbal. Previous studies generally assume that the camera is always oriented orthogonally ...Show More
Haptic feedback systems play a critical role in enriching the user experience in human-robot interaction. However, existing devices designed for evoking haptic sensations often face limitations owing to their low degree of freedom of deformation. In this study, we introduce the Funabot-Sleeve, a haptic device based on McKibben artificial muscles, and investigate its potential to evoke a range of h...Show More
Assistive robots with soft actuators do not have joints like exoskeletons and have attracted attention because of their affinity for humans. In this study, we propose a soft assistive suit called "Funabot-Plate," which is driven by artificial muscles, has no joints, and is partially equipped with rigid plates and contact force distribution sensors. Funabot-Plate is expected to be applied to rehabi...Show More
Fabric actuator (Funabot) is expected to be applied to the haptic device. On the other hand, conventional control method in fabric actuator only feeding back the surface shape by depth sensor, although haptic device evokes the tactile via the direct contact between the device and the human body. We developed the haptic device for grabbing and established the leader-follower system that include for...Show More
In this study, it is shown that the multiphase IM can be regarded as a superposition of independence, decoupled large-pole and small-pole IM by using the VSD conversion and multiphase IM drive system (IMTS: Induction Motor drive with Transmission System) that actively utilizes pole change is proposed. By deriving a mathematical formula, the factor of torque fluctuation response due to conflict of ...Show More
The field-oriented control (FOC)-based auto current regulators (ACRs) are commonly designed under the ideal assumption that the phase is obtained continuously when performing the Park transformation, but the current regulators are always discretely implemented. It will inevitably introduce non-negligible phase discretization errors with the increase of fundamental-to-switching(control) frequency r...Show More
As the theories for expanding the operation range, the inverter overmodulation strategy and the flux weakening control method are widely used on the three-phase motors. In conventional research, it was found that a dual three-phase motor can be field-oriented-controlled in the overmodulation region easier than a three-phase motor. In this study, the theory of utilizing the flux weakening control a...Show More
In this study, it is shown that the multiphase IM can be regarded as a superposition of independent, decoupled large-pole and small-pole IM by using the VSD conversion in a multiphase IM drive system (IMTS) that actively utilizes pole change. By deriving a mathematical formula, the factor of torque fluctuation response due to conflict of voltage limiter during pole number change is identified. In ...Show More
This paper investigates the feasibility and effectiveness of applying AR (Augmented Reality) technology to assist UAV (Unmanned Aerial Vehicle) pilots in collecting data for structure inspections. The challenge of using UAVs to collect inspection data is that pilots could not precisely determine where to collect qualified data. Using AR technology to provide visual assistance to pilots is expected...Show More
The emergence of sheet-type force distribution sensors has allowed direct measurement of contact force. We developed a wearable assistive robot that can directly measure contact force and investigated the gravity compensation effect of contact-force-based control. For conventional robots that do not measure the force acting between the robot and the human body (contact force) directly, a precise r...Show More
We implemented and evaluated our previous path planning method for inspection using unmanned aerial vehicles (UAVs) in real-world, and identified its shortcomings in handling positioning errors. Then, we proposed an enhanced method to address this problem. The previous method theoretically guaranteed complete coverage of targets and data quality. However, we verified it in bridge inspection experi...Show More
Position sensorless control of surface permanent magnet synchronous motors (SPMSMs) in low-speed regions is challenging because the motor has no magnetic saliency. Several methods using the block commutation drive technique to overcome this problem have been proposed; however, the rotor position is estimated only every 60° owing to the features of the block commutation drive method. Therefore, in ...Show More
Currently, vehicles are equipped with various sensors that can collect a series of driving behavior data while driving. The driving behavior data obtained in this way can be used to analyze the causes of traffic accidents and evaluate driver skills. However, when performing the above analysis, a specific driving scene is defined and driving behavior data for that driving scene is required. On the ...Show More
In this paper, a method to detect arbitrary driving scenes from actual driving behavior data is proposed. This is positioned as a necessary technology to evaluate a driver’s cognitive ability from actual driving behavior data. In order to evaluate a driver’s cognitive ability from actual driving behavior data, it is first necessary to be able to detect scenes in which cognitive ability can be eval...Show More
With the progress of information and communication technology, it has become easier to observe and store a large amount of digital data. In the field of automobiles, various sensors such as Controller Area Network, GPS sensor, and in-vehicle camera are mounted in vehicles, and it is possible to collect location, operation, and surrounding environment information while driving. The collected drivin...Show More
We developed a wearable assistive robot that directly measures the contact force acting between the robot and the human body, aiming to enhance the safety of such wearable devices. The force acting on the body is not directly measured, instead, it is estimated by measuring the torque acting on the robot joint in the wearable assistive robot. Despite the risk of failing to recognize dangerous force...Show More
This paper proposes a novel capacitor current reduction method in Dual Three-Phase PMSM Drive System. By using Model Predictive Control considering the dead time on the premise of implementation, the method modifies the three-phase voltage command generated by the PI current controller for the current reduction. The effectiveness is verified by simulation and experiment.Show More
Position sensorless control for Permanent-magnet synchronous motors has been investigated in numerous studies, but the issues of flying start at high speed are still a major problem. In our previous research, the issues on conventional position control are presented, and the reasons for these issues are distinguished as the initial response of the speed estimation. Based on this discussion, an ini...Show More
In this paper, we propose the control model for a novel dual three-phase PMSM with pseudo-triple winding structure(DTP-PMSM with PTWS) which is one of the new multiple stator winding machines. The proposed control model is represented as the extended form of the conventional dual three-phase winding machine, and the validity is demonstrated by being compared with magnetic field analysis results. F...Show More
When one inverter drives both motors, the system efficiency deteriorates if both motors have different loads. Moreover, even if their loads are the same, the system efficiency would also deteriorate if the parameters of both motors are different. To address this issue, this paper proposes optimal current control methods for both different motors using a single inverter.Show More
Finite control set-model predictive control (FCS–MPC) has a simple and intuitive optimization procedure. Therefore, FCS–MPC is increasingly being applied to control strategies for electrical drive systems. This article presents a method for servo brake control of a permanent magnet synchronous motor (PMSM) based on FCS–MPC. Accordingly, we propose a reference trajectory introduced in a cost functi...Show More
As competitive alternatives to conventional three-phase synchronous machines, synchronous multi-three-phase machines (MTPMs) are gaining increasing interests in various fields such as electrified transportation and power generation. The modular configuration is preferred for multi-three-phase drives in specific applications regarding the availability of advanced three-phase power electronics techn...Show More
A direct speed control strategy based on finite control set model predictive control (FCS–MPC) with a voltage smoother is presented herein. In the proposed concept, a finite set of smoothed voltage vectors characterized by an adjustable amplitude and a movable origin is introduced as voltage candidates in the FCS–MPC scheme. The controller predicts the future current and speed and outputs the opti...Show More
This paper proposes a new method for rotor position sensorless estimation of surface permanent magnet synchronous motor (SPMSM), wherein the sensorless position control is very difficult when the motor is at a standstill and in low-speed regions as the motor has no magnetic saliency. In this method, conductive non-magnetic materials are pasted on the rotor. When a high-frequency voltage is applied...Show More