Applied Mechanics and Materials Vols. 789-790

Abstract: Japan is becoming a super-aging society, with a population decrease and a shortage of young workers. Mechanisms using pneumatic cylinders are therefore expected to be useful to perform tasks such as day-to-day work support for elderly people. However, pneumatic cylinder includes large dead time. Thereby, traditional control system is complex, such as adding Smith compensation. Therefore, we use Predictive Functional Control (PFC). This control system is not complex even if plant includes dead time. This study evaluates the performance of force and position control systems using a pneumatic cylinder and PFC. We compare the PFC scheme with the PID control and show that PFC achieves better performance than PID control.

Abstract: The problems related to shortages in car parking spaces in dense populated cities and areas is addressed, and the categories of automated advanced car parking systems based on their different technologies is presented. The concept of an automatic car parking system is also introduced and demonstrated through the development process of a prototype using a PIC microcontroller. Simulation for the system's circuits is done with the aid of Proteus software. The hardware circuits, which are built on printed circuit boards (PCB) are interfaced with actuators and sensors for automation purposes. The hardware is assembled to automatically open entry gates for cars while there are still some unoccupied parking spaces. The entry gate will not be opened, however as long as the car parking facility is full. Proper messages are displayed on a screen to reflect the status of the car parking facility.

Abstract: Shape memory alloy (SMA) actuators are promising for miniature applications. They accomplish the shape memorization via a temperature dependent phase transformation process. Control of SMA actuators is challenging because the actuators exhibit highly hysteresis behavior. This paper presents a fuzzy-based position control scheme for a SMA actuated mass system. The control system consists of an outer-and an inner-control loop. The inner loop controls the temperature of the SMA actuators using a PI controller, whereas the outer loop, which is affected by the hysteresis of the SMA actuators, controls the position. To deal with the hysteresis in the position control loop, an adaptive fuzzy sliding-mode control method is adopted. Experimental results illustrate the success of the proposed control scheme.

Abstract: This paper presents a method for the estimation of unknown disturbances for high precision gimbal systems. Alternative to the classical methods of model inversion and filtering, we employ an asymptotically stabilizing controller which achieves the estimation process even in the presence of unstable zeros. The architecture provides an input equivalent disturbance which can be thought to capture all real disturbances in the system as well as virtual ones such as unmodelled dynamics and nonlinearities. The proposed method is illustrated on a 2-axis gimbal system where system identification is followed by the design on an integral linear quadratic regulator as the stabilizing controller which forms the base of the disturbance observer. It is seen that a random unknown disturbance is estimated successfully in the presence of additional gyro noise.

Abstract: This paper proposed semi active controller scheme for magnetorheological (MR) damper of a heavy vehicle suspension known as Tire Force Control (TFC). A reported algorithm in the literature to reduce tire force is Groundhook (GRD). Thus, the objective of this paper is to investigate the effectiveness of the proposed TFC algorithm compared to GRD. These algorithms are applied to a quarter heavy vehicle models, where the objective of the proposed controller is to reduce unsprung force (tire force). The simulation model was developed and simulated using MATLAB Simulink software. The use of semi active MR damper using TFC is analytically studied. Ride test was conducted at three different speeds and three bump heights, and the simulation results of TFC and GRD are compared and analysed. The results showed that the proposed controller is able to reduced tire force significantly compared to GRD control strategy.

Abstract: Based on the characteristics of the back electromotive force (back-EMF), the rotor position information would be detected. Hence, the main theme of this paper is to design a practical approach to detect the zero cross point (ZCP) of back-EMF through virtual neutral voltage for sensorless brushless direct current (BLDC) motor drives. In contrast to conventional methods, the real neutral voltage of motor is not needed. In order to compensate the phase delay of the back-EMF due to low-pass filter (LPF) under different speeds, a voltage-controlled phase shifter, consisted of hysteresis comparator and voltage-controlled resistor (VCR), is proposed in this paper. The detail circuit model is introduced and some experimental results obtained from a sensorless prototype are shown to confirm the practicality of proposed senosorless drive method.

Abstract: A closed-loop control algorithm is used for stabilization of a vibrating nonlinearstrain gradient micro Euler-Bernoulli cantilever beam usinglinear piezoelectric actuation.In this paper, the governing partial differential equation (PDE) of the nonlinear strain gradient beam with piezoelectric actuator is obtained. Galerkin projection method is utilized to reduce the system’s PDE equation of motion into a set of nonlinear ordinary differential equation (ODE) model. The nonlinear system is controlled by a robust linear controller which ensures the stability of the nonlinear system. Numerical simulations are investigated to demonstrate the effectiveness and performance of the designed control scheme.

Abstract: This paper proposes one of the possible techniques for interacting for shape memory alloy (SMA) actuator based tactile display, which can act as demonstrator devices. This work is focused on developing a model of a pair of antagonistic high strain SMA tension actuators with independent control of force and displacement. The technology employed utilizes two Flexinol 100 micron heat actuated wires of Titanium-Nickel (NiTi) shape-memory alloy which contract when heated under pre-stress and produces up to 5% strain recovery. This phenomenon, which provides a unique mechanism for actuation, is associated with the unique interaction between the martensite and austenite crystal structures of the SMA. Physical measurements of the behaviour of the actuator elements were performed using a laser displacement sensor to verify the fidelity of response to software commands, and to measure step response to pulse-width modulated (PWM) current control at different frequencies and duty cycles. Results yielded high accuracy across a wide range of frequencies and duty cycles, proving the SMA actuation technique has potential to present and convey useful tactile information of surface deformation for virtual environment applications.

Abstract: A vertical takeoff and landing aircraft (VTOL) like a helicopter has come to be used in environmental investigations and inspections at dangerous places. However, there is a possibility that the VTOL like a helicopter crash if the rotor stopped. Then, computational simulation in the case that a six-rotor craft can safely continue to fly even though one of six rotors stop was carried out. Then the experimental six-rotor craft was developed and the validity of our control method was examined by the flying experiment.

Abstract: This work presents a novel broadband monopole antenna for digital video broadcasting-terrestrial (DVB-T) application. The proposed antenna consists of a grating patch and a concave rectangular ground plane with defected ground plane, and the Multiple Split-Ring Resonator (MSRR). The added part in the ground plane and the meta-material are used to enable the antenna height reduction for fixed ranges of operating frequency. The antenna can operate from 468 MHz to 894 MHz frequency range corresponding to 62.5% of impedance bandwidth for |S11|<-7.5 dB. Details of the proposed antenna designs and experimental results of the constructed prototypes are presented and discussed.