A directionally transparent energy bounding approach for multiple degree-of-freedom haptic interaction

This paper presents a multiple degree-of-freedom (DOF) energy bounding approach (EBA) for enhancing directional transparency while concurrently guaranteeing stability during multi-DOF haptic interactions. It was observed that the passivity condition for multiple ports may lead to oscillatory limit cycle behavior in some coordinate directions even though the total sum of energy flow-in is positive, meaning that the system is passive. The passivity condition, therefore, needs to be applied to each coordinate in order to avoid oscillatory behavior by ensuring that each energy flow-in is always positive. The EBA is applied to guarantee passivity. For multi-DOF haptic interaction, however, the EBA in each coordinate may distort the direction of the rendered force vector since the EBA may reduce the magnitude of the rendered force and torque vectors. To resolve this problem, a simple projection method is subsequently proposed. The validity of the proposed algorithm is then experimentally confirmed, and a comparative study with previous research is presented.     

High-payload climbing and transitioning by compliant locomotion with magnetic adhesion

This paper presents a new climbing robotic mechanism for high-payload climbing and wall-to-wall transitioning. Payload capacity and transition ability are very important in climbing-robot applications for heavy industries and construction industries. The proposed robotic platform consists of three magnetic tread-wheel modules that are connected by links with two compliant joints. The front compliant joints are passive type with a torsion spring, and the rear compliant joints are active type with torque-controlled motors. A torque-controlled tail is attached at the end of the third module. Various transitions are achieved by the compliant joints, which change shape depending on the external conditions. High payloads are achieved by the large contact area of three magnetic tread-wheel modules. Detailed design issues are presented with analyses of the design parameters. The robot can perform two internal and two external transitions against gravity and every possible transition in the side surface driving direction. The robot can carry 10 kg payloads on vertical surfaces and on a ceiling. The ability to overcome a 30 mm diameter obstacle on vertical surfaces is also verified by experiments. The proposed robotic platform is going to be used in heavy industries.     

FSH scheme for high-speed handover and anti-MITM on mobile computing

As an IEEE 802.11-based mobile computing system has been established as the base structure of high-speed wireless network, interest in mobility and security of mobile terminal has increased. To reinforce security, 802.1x and 802.11i using EAP were used in standardized instrument. But it was found to be unsuitable for real time multimedia service because of the time delay. In this paper, we suggest Fast and Secure Handover (FSH) scheme which minimizes time delay in handover authentication process and prevents MITM (Man in the Middle) attack. This scheme carries out re-association process which is necessary for high-speed handover using Inter Access Point Protocol (IAPP) and Old_MSK. To make existing 802.1x-based user certification procedure suitable for high-speed handover, the terminal and pre-handover-accessed Old_AP make Rough_AP to prevent MITM. To do this, Old_AP uses the Old_MSK-used encrypted method which was used to encrypt MAC information of the mobile terminal and Old_AP. Hereby, FSH has been developed to become high-speed handover which has the 802.1x-supported security level and the skill of preventing MITM. In this paper, by simulation (NS-2), we confirmed the superiority in streaming service such as decreased handover time delay and VoIP.     

Effectiveness Analysis of DVFS and DPM in Mobile Devices

The demand for high-performance embedded processors in multimedia mobile electronics is growing and their power consumption thus increasingly threatens battery lifetime.It is usually believed that the dynamic voltage and frequency scaling (DVFS) feature saves significant energy by changing the performance levels of processors to match the performance demands of applications on the fly.However,because the energy efficiency of embedded processors is rapidly improving,the effectiveness of DVFS is expected to change.In this paper,we analyze the benefit of DVFS in state-of-the-art mobile embedded platforms in comparison to those in servers or PCs.To obtain a clearer view of the relationship between power and performance,we develop a measurement methodology that can synchronize time series for power consumption with those for processor utilization.The results show that DVFS hardly improves the energy efficiency of mobile multimedia electronics,and can even significantly worsen energy efficiency and performance in some cases.According to this observation,we suggest that power management for mobile electronics should concentrate on adaptive and intelligent power management for peripheral devices.As a preliminary design,we implement an adaptive network interface card (NIC) speed control that reduces power consumption by 10% when NIC is not heavily used.Our results provide valuable insights into the design of power management schemes for future mobile embedded systems.     

Polynomial Fuzzy Observer Designs: A Sum-of-Squares Approach

This paper presents a sum-of-squares (SOS) approach to polynomial fuzzy observer designs for three classes of polynomial fuzzy systems. The proposed SOS-based framework provides a number of innovations and improvements over the existing linear matrix inequality (LMI)-based approaches to Takagi-Sugeno (T-S) fuzzy controller and observer designs. First, we briefly summarize previous results with respect to a polynomial fuzzy system that is a more general representation of the well-known T-S fuzzy system. Next, we propose polynomial fuzzy observers to estimate states in three classes of polynomial fuzzy systems and derive SOS conditions to design polynomial fuzzy controllers and observers. A remarkable feature of the SOS design conditions for the first two classes (Classes I and II) is that they realize the so-called separation principle, i.e., the polynomial fuzzy controller and observer for each class can be separately designed without lack of guaranteeing the stability of the overall control system in addition to converging state-estimation error (via the observer) to zero. Although, for the last class (Class III), the separation principle does not hold, we propose an algorithm to design polynomial fuzzy controller and observer satisfying the stability of the overall control system in addition to converging state-estimation error (via the observer) to zero. All the design conditions in the proposed approach can be represented in terms of SOS and are symbolically and numerically solved via the recently developed SOSTOOLS and a semidefinite-program solver, respectively. To illustrate the validity and applicability of the proposed approach, three design examples are provided. The examples demonstrate the advantages of the SOS-based approaches for the existing LMI approaches to T-S fuzzy observer designs.     

Effects of blend composition on the morphologies and physical properties of polycarbonate/acrylonitrile-butadiene-styrene blends

The morphologies and physical properties of twin-screw-extruded polycarbonate/acrylonitrile-butadiene-styrene (PC/ABS) blends with various blend ratios are studied. The needle-like co-continuous phase in PC-rich blends changes to the sea-island phase for blend ratios of more than 50 wt% ABS. While pure PC exhibits an almost-Newtonian flow behavior, PC/ABS blends exhibit the interesting rheological transition. The viscosities of the ABS-rich blends at low shear rates are almost equal to those of the pure ABS polymer. The yield stress for the PC/ABS blend ratio of 3:7 is the highest in composition. At the frequency of 10 rad/s, the PC-rich blends exhibit highly viscous properties, whereas the ABS-rich blends present highly elastic properties as the temperature increases. Moreover, the ABS polymer in the PC/ABS polymer blend induces significant change at the fracture surface of PC, transitioning from brittle to ductile nature.     

Direct adaptive controller for nonaffine nonlinear systems using self-structuring neural networks

A direct adaptive state-feedback controller is proposed for highly nonlinear systems. We consider uncertain or ill-defined nonaffine nonlinear systems and employ a neural network (NN) with flexible structure, i.e., an online variation of the number of neurons. The NN approximates and adaptively cancels an unknown plant nonlinearity. A control law and adaptive laws for the weights in the hidden layer and output layer of the NN are established so that the whole closed-loop system is stable in the sense of Lyapunov. Moreover, the tracking error is guaranteed to be uniformly asymptotically stable (UAS) rather than uniformly ultimately bounded (UUB) with the aid of an additional robustifying control term. The proposed control algorithm is relatively simple and requires no restrictive conditions on the design constants for the stability. The efficiency of the proposed scheme is shown through the simulation of a simple nonaffine nonlinear system.     

The Effect of Carbon in Slag on Steel Reoxidation by CaO‐SiO2‐Al2O3‐MgO‐MnO‐FetO Slags

An equilibrium study was carried out at 1873K to ascertain the effect of carbon in CaO‐SiO₂‐Al₂O₃‐MgO‐MnO‐Fe_tO slag systems on their Fe_tO and MnO activity coefficients, representing the slags’ thermodynamic potential for steel reoxidation. Both γf e_to and γm no showed not only a sharp increment but also a simultaneous slow decrement by increasing carbon content in slag, suggesting opposite roles of the carbon according to its stable forms. XPS (X‐ray photoelectron spectroscopy) was introduced to clarify the stable forms of carbon in slag. XPS results prove that carbon dissolves in slag as carbonate, and carbide ions under oxidizing and reducing atmospheres, respectively. It was concluded that carbonate ions increase γf e_to and γm no , but that carbide decreases them. This paper suggests an application method of the present results to actual ladle refining processes, in order to enhance steel cleanliness with maintaining (Fe_tO + MnO) in slag to some allowable amount.