Electroaerodynamics (EAD) is a phenomenon that generates a gas motion by applying high voltage between electrodes. One method of creating thrust with EAD is the use of the corona discharge, which is a self-sustaining discharge. Since it does not require any moving parts, the corona discharge produces thrust robustly and quietly. Therefore, this thrust system is expected to be utilized as the thrust source for drones. However, since the relationship between thrust and applied voltage is nonlinear, dealing with this problem in control is indispensable. Although some studies have been conducted on control methods with the corona discharge, few have been performed on multi-degrees of freedom (DOF) control based on theoretical modeling, which is essential for achieving attitude control during flight. Thus, this paper proposes a control system based on theoretical modeling to realize 2-DOF height and angle control. This study utilizes the idea of differential mode and voltage range limitations and introduces a disturbance observer (DOB) to construct a control system. Two simulations are conducted to verify the effectiveness of the proposal. The first simulation shows that the proposal can follow the command value with small errors, indicating the possibility of multi-DOF control. The second simulation revealed that the proposal significantly suppressed attitude change under disturbance and contributed to improved responsiveness.

A method to generate wind based on electrohy-drodynamics (EHD) using corona discharge has been applied to various thrust-producing devices. However, the relationship between electrode structure and wind-induced thrust is still unclear, and electrode design guidelines have not yet been established. Therefore, this paper aims to formulate the relationship between the thrust and electrodes' configuration by taking continuous data from experiments. Experiments were conducted to investigate the change in thrust when the gap between electrodes was varied continuously, and when changing the shape of electrodes, after a preliminary experiment on the relationship between voltage polarity and thrust. Experiments revealed that thrust increased as the gap decreased at the same voltage, thrust began to be generated at a lower voltage when the emitter electrode was needles than when it was a wire. From these experimental results, it was demonstrated that the thrust was expressed as a linear equation of voltage, that there is an inverse proportion-like relationship between the gap and thrust, and that the corona discharge inception voltage became lower when needles were used as the emitter electrode, where the voltage applied, instead of a wire. These findings and considerations will greatly help to establish guidelines for designing devices using this method, which generates thrust without any moving parts.

A corona discharge is a kind of self-sustaining discharge that is generated by applying high voltage to asymmetric electrodes. The thrust by the corona discharge is expected as a new actuator since it has no moving parts, is quiet, and is robust. However, the relationship between the applied voltage and the thrust is highly nonlinear, which means that this problem must be solved by control. Furthermore, a control system that compensates for disturbances such as wind and modeling errors is also required. Therefore, this paper proposes a control system with a voltage range limitation that takes into account the characteristics of corona discharges and the disturbance observer to improve disturbance suppression characteristics. Two experiments were conducted to confirm the effectiveness of the proposed method. The first experiment shows that the proposed method improves the response speed by 70.0% in step response. The second experiment indicates that the proposed method enhances the response speed by 60.0% in disturbance response and suppresses angle change by 42.3%. Through experiments, it is confirmed that the proposed method succeeded in attitude control on the centimeter order and improved control performance.

Robots are being developed to perform tasks in homes and factories autonomously. Several studies have examined motion generation based on haptic information, and some studies consider the environment as physical property information. However, there is a trade-off between the accuracy and the time required for the physical property estimation. Therefore, in this study, we propose a method for estimating physical properties based on training the relationship between the two estimation models. The first is a fast sequential estimation model, and the second is a highly accurate posterior estimation model. Training the relationship between the two models makes highly accurate sequential property estimation possible. Validation results showed improved accuracy of property estimation for learning samples and some untrained samples.

In this paper, we discuss the use of pulse width modulation (PWM) with high-carrier frequency as an input for functional electrical stimulation (FES). Previous studies have shown that the relationship between muscle inflow current and joint exerted force can be approximated by a first-order lag system that includes the dead time. This characteristic can be improved by using an input based on high-frequency PWM. In PWM, the component of the carrier frequency can be made smaller than pulse amplitude modulation (PAM), and in addition, the carrier frequency can be set to a high value. This means that it is possible to move only the frequency component of the desired operating command without any effect of the carrier frequency. First, PWM and PAM were experimentally compared. Second, the performances achieved by using high-carrier frequency and low carrier frequency were compared. Finally, the control performance achieved using a sinusoidal motion command was verified by changing the carrier frequency. The gain attenuation caused by the non-linearity of the human body was clarified for high-carrier frequencies. Therefore, the control performance was worse than the originally desired result. However, the advantages of using high-carrier frequency to reduce fatigue attenuation and to suppress the effect of carrier frequency were demonstrated.

Bilateral control, a remote-control technique, is used to work at a distance. However, many existing bilateral control systems have two common problems: 1) it is difficult to create a system like a human hand, that has multiple degrees of freedom and 2) if the mechanism becomes too complicated, operators feel restrained and experience discomfort. Because, for these reasons, the bilateral control of fingers has not been accomplished to date, we aimed to overcome this by applying functional electrical stimulation (FES). In our experiments, through an adhesive electrode pad, electrical stimulation was delivered to the muscles that flex and expand the metacarpophalangeal joints of the thumb and middle finger. Position-symmetrical bilateral control was implemented so that the deviation of the master's and slave's positions relative to each other was zero degrees. A sliding mode controller was used as a position controller. We found it possible to control multiple degrees of freedom; however, we found areas where the number of tracking errors was large. We speculated that the middle finger did not bend, because the arm rotates as the thumb was abduction, therefore the position of the motor point of the middle finger deviates from the position of the pad.

In this study, we developed a method to estimate the relationship between stimulation current and volatility during isometric contraction. In functional electrical stimulation (FES), joints are driven by applying voltage to muscles. This technology has been used for a long time in the field of rehabilitation, and recently application oriented research has been reported. However, estimation of the relationship between stimulus value and exercise capacity has not been discussed to a great extent. Therefore, in this study, a human muscle model was estimated using the transfer function estimation method with fast Fourier transform. It was found that the relationship between stimulation current and force exerted could be expressed by a first-order lag system. In verification of the force estimate, the ability of the proposed model to estimate the exerted force under steady state response was found to be good.

This paper describes the reduction of chattering in functional electrical stimulation (FES) with Smith compensator. We proposed a bilateral controller using FES. In the bilateral controller, in addition to normal remote control, the reaction forces of the distant location are transmitted back to the operator. Therefore, the operator feels like being in the distant location. In controlling of the human body using FES, a dead time occurs. As a result, high-frequency vibration (called chattering) occurs. In this paper, we propose a control method suppressing chattering in FES. In the experiment, the performance of the proposed method was verified by target value control and bilateral control. In the target value control, chattering was suppressed by the proposed method. However, in the bilateral control, chattering was not be suppressed by the interference of the time delay of the two subjects.

This paper describes bilateral control using functional electrical stimulation (FES). Bilateral control is a teleoperation system using force feedback. If we can use it in everyday life, it could allow remote diagnosis by doctors and communication of tactile information. However, in conventional studies of bilateral control, operators must wear robot arms. Using them in everyday life is not desirable, because they are restrained and make human feel uncomfortable. Therefor, we propose the use of FES in the transmission of force information. An experiment on bilateral control of elbow joints with five healthy male participants was conducted. Biceps brachii muscles and triceps brachii muscles were stimulated using adhesive electrical pads. Position symmetrical bilateral control was implemented so that the deviation of the position of each other is 0. The angles of the elbows were measured by encoders, and a proportional-integral-derivative (PID) controller was implemented as a position controller. The experimental results show that the proposed method showed good performance in the practical viewpoint. However, the elbows of some subjects could not be successfully controlled because interference current occurred between their muscles.