Showing papers in "Journal of the Society of Instrument and Control Engineers in 1981"

Some Results on the Qualitative Theory of Matrix

Abstract: In this paper, we discuss the sign stability and the potential stability for the linear time invarient system described by dx/dt=Ax, x∈Rn, A∈Rn×n. The necessary and sufficient conditions for sign stability are obtained. The sufficient conditions for potential stability are also discussed with the concept of cycle decomposition. The results obtained are more general than those so far known. The concept of inertia preservation, which is the generalization of sign stability, is introduced to classify matrices from the structural point of view. Some system structures to preserve inertia are shown.

Optical Proximity Sensor by Using Phase Information

Abstract: In this paper, an optical proximity sensor based on measuring the phase shift of the modulated light reflected from the target object is described. The optical proximity sensors developed so far, have been based on detecting the intensity or timing of light reflected, but here, we made up the simple sensor based on measuring the phase shift of modulated light reflected from the object. It can measure the distance to the object and the inclination angle of the object without being affected by the reflection factor. The sensor is basically composed of two light sources and one optical detector, all of which face the target object. For distance measurement, two of the light sources are located asymmetrically around the detector and are driven by sinωt and cosωt signals. The distance is a function of the phase angle of the detected reflex light signal. For inclination-angle measurement, two of the light sources are located symmetrically around the detector. The inclination angle is a function of the phase angle of the detected light signal. Testing of a prototype sensor and signal-processing circuit demonstrated its effectiveness. This sensor, which can detect the situation of objects at close range, is particularly suited for use in flexible automation systems.

Image Instrumentation of Plants Exposed to Air Pollutants

Abstract: Heat and mass transfer on a leaf were examined from the standpoint of evaluating distributional patterns of physiological informations such as transpiration rate, stomatal resistance and air pollutant sorptions from leaf temperature distribution measured by an instrumentation system of thermal infrared images, and models for the evaluating were derived. Furthermore, parameters of the models, accuracies of environmental controls and measurements on the leaf and so on were examined by experiments. As a result, transpiration rate and stomatal resistance to water vapor diffusion on the leaf were evaluated within accuracies

An Adaptive Method for Trajectory Control of manipulators

Abstract: In general, it is very difficult to control motions of mechanical manipulators by usual deterministic control methods in a wide range of motions, because of complex nonlinearities of the dynamics and uncertainy of parameters of the system. In this paper, we propose an adaptive control method to track desired trajectories wich are described by arbitrary task-oriented coordinates. Since the control method requires neither a knowledge of parameters of the system nor complicated calculation, it is easy to implement the method by a micro-computer. Effectiveness of the proposed control method is verified by several simulations. Particularly, an adaptive control law for compensating an acceleration term of the trajectory is shown to be very effective in case of tracking a trajectory of fast motion.

Low Order Modeling of Biped Locomotion System Using Local Feedback

Abstract: A new low order model is developed for biped locomotion system having five links by using predominant modes when local feedback is considered. It is shown that these predominant modes are not influenced by the coefficient of local feedback. By computer simulation, this low order model has been proved to provide good approximation for the original high order system especially with respect to the center of gravity and the angular momentum of the biped system. These properties are most important for the low order model of dynamical walking. Since the model is very simple and accurate, it can be used as the model for deciding global strategy of multilevel control.

Modelling and Monitoring a Manipulation Environment

Abstract: The development of high-level manipulator language will cause an explosion of decralations about the real world environment. Procedures may be written in a few lines of statements of higher level language, while world descriptions will still require hundreds of statements. Since the world model is a complex data base describing three-dimensional objects, it is not easy to construct it. This paper describes a system which enables an user to construct objects models interactively. The system provides a laser spot as a measuring tool and a display monitor as a visualizing device of the internal data base and the real world. Using these devices, the user can supervise the process of model construction and check the result very easily.

Degradation of Performance Index Value Caused by Quantization Errors in a Digital Control System

Abstract: In this paper, the degradation of performance index value caused by quantization errors incurred in a digital control system having the A. D-D. A converter of finite quantization figure number is analyzed. It seems that between this degradation and the hardware cost of the A.D-D.A converter exists a tradeoff of the digital control design problem. It is shown that the degradation in a linear quadratic optimal control problem is formulated as the sum of quantization errors occurring at each sampling time in a quadratic form. In case the initial states are unknown random variables, the expected value of degradation is derived under the assumption that the probability density function of quantization errors is uniform. The optimal quantization figure number with which the expected value of degradation becomes equal or less than the specified allawable value of degradation, is determined. Digital simulation results of a second order control system are presented to demonstrate the feasibility of the approach.

A Feedback Control of Task-Oriented Coordinate for Manipulators

Abstract: In this paper we consider the dynamic control of manipulators from the view point of mechanics, and propose a new method for task-oriented coordinate control which does not require a transformation from task-oriented coordinates to joint angles. The proposed method can be easily implemented by a microcomputer and suited to the sensor feedback control. Furthermore, it is shown that the proposed method is applicable even when holonomic constraints are added to the system, and when redundancy or singularity arises in the relation between task-oriented coordinates and joint angles. Effectiveness of the proposed method is verified by computer simulation utilizing an arm model with four degrees of freedom.