Yoshitaka Matsuda

Experimental evaluation of teleoperation system with force-free control and visual servo control by human operator perception

This research considers the teleoperation of an articulated robot arm by means of force-free control and visual servo control (VSC) over communication channels using the Internet technology. A semi-autonomous type teleoperation system contains a human supervisory control and VSC schemes and switches one scheme to another for accomplishing the required task accurately. The main investigation is carried out to find how it effectively improves the accuracy and the effectiveness of the teleoperation after provision of a visual feedback channel to the system. The system accuracy, effectiveness, repeatability and handleability based on the human operator’s skills and operator’s cognitive aspects are evaluated using experimental results and statistical data analysis. Effectiveness of the statistical analysis is assured by increasing the number of experiment data and assuming environmental factors, and implicit variables maintain to be unchanged. Correlation coefficients are calculated to find out how controlled input parameters are related to the successful output given by the system.

Teleoperation of robot arm with position measurement via angle-pixel characteristic and visual supporting function

In this paper, a teleoperation system of a robot arm with position measurement function and visual supporting function is developed. The working robot arm is remotely controlled by the manual operation of the human operator and the autonomous control via visual servo. The visual servo employs the template matching technique. The position measurement is realized using a stereo camera based on the angle-pixel characteristic. The visual supporting function to give the human operator useful information about the teleoperation is also provided. The usefulness of the proposed teleoperation system is confirmed through experiments using an industrial articulated robot arm.

Controller design for liquid level control of separator in an OTEC plant with Uehara cycle considering disturbances

This research deals with the design of PI controller for the liquid level control of separator in an ocean thermal energy conversion (OTEC) plant with Uehara cycle by considering some kinds of disturbances. The PI controller is designed for a liquid level model under H∞ constraint. The effectiveness of the designed PI controllers is evaluated through simulations considering disturbances.

Development and evaluation of simulation model for force-free control strategies

Construction and evaluation of the two different strategies of force-free control of industrial type robot arm is presented in this paper. First, robot arm dynamic model for two link model and basic structure of force-free control method are described. Then two different force-free control architectures are illustrated. Two different force-free control strategies are force-free control by dynamic external torque and force-free control by dynamic torque independent compensation, respectively. Analysis of the each type of force-free control strategy is carried out for the single link and two links perspectives of industrial robot arm configurations by means of simulations under Matlab/Simulink environment. The model characteristics of the force-free control are exploited to discuss the application scenarios. Moreover, analysis of the force-free control is carried out by using real robot parameters throughout the simulations. Since the force-free control deals with external forces applied on the robot arm, it can be used to illustrate the interactive force control between a human and a robot arm by passive motion over an external force.

Teleoperation system for a mobile robot with visual servo mechanism based on automatic template generation

In this paper, a teleoperation system for a mobile robot with visual servo mechanism is developed. The teleoperation system has two kinds of motions: rough motion and accurate motion. In the rough motion, the mobile robot is controlled manually. In the accurate motion, it is done autonomously by visual servoing, where the template matching technique is used to realize the visual servoing. The template image is automatically generated by only assigning one pixel of the target object. The usefulness of the developed teleoperation system is evaluated by experimental result for the automatic template generation and the teleoperation.

Model construction of heat source in an OTEC pilot plant for stabilization control based on experimental data

In ocean thermal energy conversion (OTEC) plant, electricity is generated by heat energy from temperature difference between warm seawater at surface and cold seawater in depth. OTEC plants have an evaporator as one of the most important devices. Indeed, the evaporator evaporates the working fluid to rotate the turbine connected to the generator. In this research, a model of heat source system in an OTEC pilot plant for stable operation of the plant is constructed. In the OTEC pilot plant, the evaporation of the working fluid is realized by warm water from a boiler. Therefore, it is important to keep the temperature of warm water constant. Since the temperature of warm water can be changed by manipulating the valve opening, first order models to describe the relationship between the temperature and the valve opening are constructed based on experimental data. The effectiveness of the constructed models was verified through simulation.

Characteristic analysis of visual evoked potentials and posterior dominant rhythm by use of EEG model

Visual evoked potentials (VEPs) are the electrical responses from the brain concerned with visual information processing. Amplitude of VEPs is smaller than that of background EEG activity, and the stimulus-locked averaging method is usually used for obtained the waveform. VEP response to each stimulus is not completely the same however it is varying with its amplitude and duration. Therefore, amplitude of averaged VEP waveform deteriorates due to their variability in raw data. Feature extraction of background EEG activity during visual stimulation is also a one of significant items in VEP analysis. In that case, separation of VEP component and background EEG component (mainly posterior dominant rhythm) is crucial. In the past, we proposed the method of estimating both amplitude of VEP and dominant rhythm by use of EEG model. This present study, the proposed method was applied to actual recorded VEP data and its effectiveness was evaluated. EEGs with visual stimulus were recorded from nine healthy young adults. Usefulness of the proposed method was investigated by comparing the conventional power spectrum averaging method. The proposed method will be applicable to show an accurate VEP analysis and characteristic analysis of background activity under visual stimulus.

An improvement on LQG controller for liquid level control of separator in an OTEC experimental plant using Uehara cycle

This research proposes an improved controller design methodology for liquid level control of separator in an ocean thermal energy conversion (OTEC) plant using Uehara cycle. In the previous research, the control system design for liquid level control of separator was conducted based on the LQG control theory with state estimation via stationary Kalman Filter. However, it is verified by the simulation of this research that an assumption on an integral degrades the estimation accuracy of a state variable. To cope with this problem, in this research, the reset of integration is introduced to the control system. The usefulness of the proposed method is confirmed through simulation.

Evaluation of a liquid level model of separator in an OTEC experimental plant using Uehara cycle via different experimental data

This research is concerned with the evaluation of a liquid level model of separator in an ocean thermal energy conversion (OTEC) plant using Uehara cycle. The liquid level model is described by the polynomial of valve opening and white Gaussian process. The mean and the variance of white Gaussian process are determined by two kinds of experimental data. The behavior of the liquid level model is evaluated by numerical simulations based on two kinds of experimental data. The simulation results indicate that the model construction of liquid level can ben successfully conducted even if the experimental data to be used are different.

Operation systems for a mobile robot using EOG and EMG

In this research, systems to operate a mobile robot by using electrooculographic (EOG) and electromyographic (EMG) signals are developed. Suitable control command signals for the mobile robot are generated by processing EOG and EMG signals appropriately. By reducing the number of electrodes, a simplified operation system for mobile robot is also constructed. The effectiveness of the proposed operation systems is verified by experiment.