In spacecraft attitude control, the quaternion is often used as a kinematic parameter, simply because it has no singularities. In the tracking problem of an attitude control, the error quaternion is needed for quaternion feedback. Due to complexity of the quaternion math, the error quaternion is sometimes misunderstood and its incorrect denition is used for attitude control. Even in such cases, the tracking objective is achieved to some extent. In this paper, we consider attitude control of a spacecraft with RWs and examine the property of the error quaternion.
This paper considers position and attitude control of large flexible space structures composed of a number of subsystems(substructures) which are interconnected by flexible links modeled by springs and dampers. It is assumed that sensors and actuators are collocated in each subsystem. The purpose of the paper is to propose a decentralized control method by local proper controllers using only displacement / angular displacement output, which makes both each closed-loop subsystem and an overall closed-loop system not only robustly stable against uncertainty of characteristic parameters such as mass, damping, and stiffness, but also optimal for a quadratic cost function.
This paper describes a method for detection of change of state of the indoor environment using the change of the strength of the wireless LAN signals. For the monitoring system of the person’s safety in the indoor environment, camera devices are widely used because of the width of view; however, it is difficult to apply the monitoring the person and home environment because of the privacy concerns. We need a method for detection of change of state of the environment using the sensing device that can obtain the global information, but cannot obtain the shape of the indoor environment directly. In this paper, we focus on change of the pattern of the strength of wireless LAN signals because the signal strength has uncertainty and changes due to the change of the state of the environment. The method detects the change of the pattern of the signal strength based on the singular spectrum transformation of the time series of the strength of the wireless LAN signals.Then, the method detects the change of the state of the indoor environment such as the movement of the target persons. Experimental results show the feasibility of the proposed method.
This paper is concerned with the dominant pole analysis of asymptotically stable time-delay positive systems (TDPSs) with multiple delays. It has been shown recently that the dominant pole of a stable TDPS with a single delay increases and hence the convergence performance degrades according to the increase of the delay, if and only if the associated state space matrices satisfy an eigenvalue-sensitivity condition. This paper extends these preceding results to TDPSs with multiple delays. As a main result, we show that the dependence of the dominant pole upon the variation of multiple delays can be completely determined by the eigenvalue-sensitivity condition with respect to the state space matrices corresponding to the varying delays.
In this paper, a simple personal identification system is presented, using data associated with corneal thickness measured by OCT (Optical Coherence Tomography). The proposed method divides the cornea into thirty two fan-shaped segments, each of which has the same area, using thirty two radiuses. It generates the thirty-two-dimensional (or sixty-four-dimensional) vector for some test subject as the registered data at some time point, and adds it to a set. The data consists of element values equal to minimum values and/or maximum values on the above radiuses. When the test subject takes medical practice, the proposed method generates thirty-two-dimensional (or sixty-four-dimensional) vector for the corresponding test subject as the collation data, and calculates the Euclidean distance between the collation data with each of the vectors in the set. It judges the test subject corresponding to the given collation data to be that of the registered data with the shortest distance to the given data. Experimental results establish that the proposed method achieves one hundred percentage as the identification rate on assumption that the number of test subjects is 30, when element values of the registered data and collation data are associated with pachymetry.
This paper proposes a system for improving daily lives of elderly people to ensure health, which we termed as “health promotion support system”. In order to realize an enriched life style among elderly people, daily health care is important. Therefore, we propose a system where robot partners will assist in exercising activity among elderly people. This system is intended to provide encouragement,exercise guidance and exercise evaluation to motivate voluntary and active participation from the elderly through the help of robot partner. The robot partner presents appropriate comment based on the score using calculated information from quantitative evaluation of the measured data. Elderly people can get a good evaluation by raising their intrinsic motivation. In addition, elderly people’s self-efficacy can be improved using encouraging speech from robot partner. Finally, we consider the element of communication to support voluntary participation based on survey results from elderly people and caregiver.