In this paper we present a stability theory for discontinuous dynamical systems (DDS): continuous-time systems whose motions are not necessarily continuous with respect to time. We show that this theory is not only applicable in the analysis of DDS, but also in the analysis of continuous dynamical systems (continuous-time systems whose motions are continuous with respect to time), discrete-time dynamical systems (systems whose motions are defined at discrete points in time) and hybrid dynamical systems (HDS) (systems whose descriptions involve simultaneously continuous-time and discrete-time). We show that the stability results for DDS are in general less conservative than the corresponding well-known classical Lyapunov results for continuous dynamical systems and discrete-time dynamical systems. Although the DDS stability results are applicable to general dynamical systems defined on metric spaces (divorced from any kind of description by differential equations, or any other kinds of equations), we confine ourselves to finite-dimensional dynamical systems defined by ordinary differential equations and difference equations, to make this paper as widely accessible as possible. We present only sample results, namely, results for uniform asymptotic stability in the large.
Data for human sleep study may be affected by internal and external influences. The recorded sleep data contains complex and stochastic factors, which increase the difficulties for the computerized sleep stage determination techniques to be applied for clinical practice. The aim of this study is to develop an automatic sleep stage determination system which is optimized for variable sleep data. The main methodology includes two modules: expert knowledge database construction and automatic sleep stage determination. Visual inspection by a qualified clinician is utilized to obtain the probability density function of parameters during the learning process of expert knowledge database construction. Parameter selection is introduced in order to make the algorithm flexible. Automatic sleep stage determination is manipulated based on conditional probability. The result showed close agreement comparing with the visual inspection by clinician. The developed system can meet the customized requirements in hospitals and institutions.
This paper is concerned with the analysis of pole constraints in servo system design for non-minimum phase (NMP) systems. We first characterize the achievable closed-loop system for a SISO plant. For simplicity, we assume that the plant has only one NMP zero. Based on the characterization and the tracking condition, we show for some combinations of degree and relative degree of the closed-loop system that the admissible location of poles is restricted. For these cases, we provide a quantitative measure for the limitation. We also provide its concrete formula for some specific cases.
This paper considers robust stability of an interconnection of a linear time-invariant differential nominal system and passive uncertainties in the behavioral framework. A generalized version of the well-known passivity theorem is formulated by using quadratic differential forms. Based on the generalized passivity theorem, it is proved that, if the nominal system is Φ-passive, the interconnection is robustly stable against strictly (−Φ)-passive uncertainty. Moreover, we show that the Φ-passivity of the nominal system is a necessary and sufficient condition for robust stability with regularity constraint of the uncertain interconnection.
We propose a method of remote bilateral-control of master-slave manipulators with an environment observer. The adaptive environment observer estimates characteristics of the environment in a remote place. Thus, the system predicts a virtual environment that is generated by an actual environment. The proposed system exhibits good operatability and tracking when the slave system presses a compliant wall under the condition of information transmission delay. We confirm the effectiveness and safety of the proposed system by experiments.
In this paper, to provide precise force sensation of human operator, a twin direct-drive motor system with wire rope mechanism has been developed. The human-robot interaction force and the wire rope tension are independently controlled in acceleration dimension by realizing the dual disturbance observer based on modal space design. In the common mode, it is utilized for control of vibration suppression and wire rope tension. In the differential mode, the purity of human external force with compensation of friction force is obtained. This mode is useful for control of the interaction force of human. Furthermore, the human-robot system that has the ability of support of human interaction force is also proposed. The interaction force generation based on B-spline function is applied to automatically adjust the smooth force command corresponding to the adaptive parameters. To analyze the human movement stroke, the multi-sensor scheme is applied to fuse both two motor encoders and acceleration sensor signal by using Kalman filter. From the experimental results, the ability to design different level of assistive force makes it well suited to customized training programs due to time and human movement constraints.
Network based wireless sensing has become an important area of research and various new applications for remote sensing are expected to emerge. One of the promising applications is structural health monitoring of building or civil engineering structure and it often requires vibration measurement. For the vibration measurement via wireless network, time synchronization is indispensable. In this paper, we introduce a newly developed time synchronized wireless sensor network system. The system employs IEEE 802.11 standard based TSF counter and sends the measured data with the counter value. TSF based synchronization enables consistency on common clock among different wireless nodes. We consider the scale effect on the synchronization accuracy and the effect is evaluated by stochastic analysis and simulation studies. A new wireless sensing system is developed and the hardware and software specifications are shown. The experiments are conducted in a reinforced concrete building and results show good performance enough for vibration measurement purpose.
A new Branch and Bound method is given for the scheduling of the group elevator system with full information. Full information means that not only the parameters of the elevator systems but also the arrival time, origins and destinations of all the passengers who are to be served are known beforehand. The performance obtained by solving the full information problem is the best performance that the elevator scheduling algorithm can achieve and then can be used to measure how good an elevator scheduling algorithm is. The method can handle the continuous time event and is based on the concept of “trip”, which refers to the movement of the car without changing the direction and with at least one passenger being served.
The goal of this paper is to provide an elementary proof for the exactness of the (D,G) scaling. The (D,G) scaling has vast application area around control theory, optimization and signal processing. This is because, by applying the (D,G) scaling, we can convert inequality conditions depending on an uncertain parameter to linear matrix inequalities (LMIs) in an exact fashion. However, its exactness proof is tough, and this stems from the fact that the proof requires an involved matrix formula in addition to the standard Lagrange duality theory. To streamline the proof, in the present paper, we clarify that the involved matrix formula is closely related to a norm preserving dilation under structural constraints. By providing an elementary proof for the norm preserving dilation, it follows that basic results such as Schur complement and congruence transformation in conjunction with the Lagrange duality theory are enough to complete a self-contained exactness proof.