Shigeru Kurosu

Continuous mass measurement in checkweighers and conveyor belt scales

This paper deals with the development of a signal processing algorithm for checkweighers to realize a much higher speed of operation and highly accurate measurement of the mass of an object during crossing a conveyor belt. The experimental results on checkweighers suggest that the filtering algorithm of FIR type designed under the consideration on the dynamics of checkweighers is effective enough for practical applications.

Stability Analysis on Air Conditioning System

Room air temperature control of a single zone space is studied. In air conditioning systems, no matter what the forcing-a step or impulse in setpoint or slight disturbance-the loop can easily get into huntings. Variable air volume (VAV) control is very common for air distribution in air conditioning system today. The supply air flowrates to the room can be controlled by damper or by fan speed control. Such a VAV system is assumed to be essentially to the source of huntings. To explore the possible existence of huntings, a dynamical system model is formulated as a bilinear model with time-delayed feedback (by P or PI control actions), and a parametric analysis of the stability region is presented. Results are given showing the stability region affected by the selection of setpoint values and control parameters. This analysis is conducted to help us tune the PID controllers for achieving good control performance

Tuning method of PID controller for desired damping coefficient

In the previous paper, we proposed the tuning method of PI controller for a plant model described by a first-order lag plus deadtime system based on a desired damping, and demonstrated its effectiveness and limitation by simulation studies. The PI parameters have been adjusted so that their influence on the damping was transparent. It is well known that the derivative action is effective in obtaining the desired damping. In this paper, of particular interest to us is how to tune PID controller to suppress overshoot. In tuning controllers it is often convenient to specify a damping coefficient of the closed system. For PID control, the integral time Td and the derivative time Td are kept fixed to degenerate the order of the closed-loop transfer function. This can be easily led to pole-zero cancellation. Thus, the only one parameter of PID controller to be adjusted now becomes the proportional gain kp. It can be concluded that the PID controller provides a much better response than the PI controller presented last year. The resultant graphical comparisons document how to give a guide line for tuning of PID controller.

Dynamical Characteristics of Gyroscopic Weight Measuring Device

This paper describes analytical and experimental studies about an entirely new system for measuring forces using a gyroscope (called Gyroscopic Weight Measuring Device, or simply GWMD throughout this paper) which provides precise direct digital output proportional to the single axis weight applied. In spite of the complexity of the servo-mechanism, the action of the GWMD is inherently linear, hysteresis, and drift free. Topics in this paper are summarized as follows: 1) The principal dynamical characteristics of the GWMD using a two-degree-of-freedom mathematical modelfor a gyroscope are an) alyzed theoretically. 2) The GWMD is designed with suitable parameters and constructed. Some systematic errors caused by various influences are examined. 3) Performance tests are promising for practical applications. The GWMD constructed in this study offers a repeatable accuracy up to 1/15,000 for weight in the range 0 to 150 N.

Development of Mass and Length Measurement System on Conveyor Belt

Our aim is to establish a measurement system that enables highly accurate measuring mass and length of moving products with a relatively high speed on a conveyor belt. In this paper, effectiveness of the proposed measurement system is demonstrated by an analysis of a digital image taken by a digital camera. In our experimental results, it can be found the following: First, our discrimination method of colors is that there is no need to count the number of pixels for all three primary colors, but the only one component indicated the highest value of graduation should be counted. Secondly, the length measurements are performed using these six kinds of the reference unit pixels for the products having lengths within a range from 200 to 1200 mm. It is obvious that even through any reference lengths used, the required accuracies less than plusmn5 mm cannot be achieved without calibration method

Stability analysis of interacting systems in air-conditioning system

Interacting systems between room air temperature of a single zone space and supply air temperature controls are considered. In air conditioning systems, the control loop can easily get into huntings. Variable air volume (VAV) control is very common for air distribution in air conditioning system today. Such interactions are assumed to be essentially to the source of huntings. To explore the possible existence of huntings, dynamical system models of the interacting systems are formulated as a bilinear model with time-delayed feedback, and a parametric analysis of the stability region is presented. Results are given showing the stability region affected by the selection of setpoint values and control parameters. This analysis is conducted to help us tune the PID controllers for achieving good control performance.

Tuning Method of PI Controller for Given Damping Coefficient

This paper presents a tuning method of PI controller based on a desired damping coefficient. The plant model described by a first-order lag plus deadtime system is considered. The ultimate sensitivity method presented by Ziegler and Nichols has been still widely used, but it has the disadvantage that gives an oscillatory response. In recent years a less oscillatory response has been judged to be more appropriate for process controls. In tuning PI controller it is often convenient to determine the damping coefficient to obtain the desired control performance. The deadtime element can be approximated by the Pade equation to determine the damping coefficient for the equivalent second-order lag system. For PI control, the integral time is normally chosen equal to the time constant of a plant to degenerate the order of the closed-loop transfer function so that pole-zero is cancelled. As a result, the relations among the gain constant, the time constant, the deadtime of the plant and the proportional gain of the controller are clarified when the desired damping coefficient is provided

Air-Conditioning PID Control System with Adjustable Reset to Offset Thermal Loads Upsets

The heating, ventilating, and air-conditioning (HVAC) systems have huge different characteristics in control engineering from chemical and steel processes. One of the characteristics is that the equilibrium point (or the operating point) usually varies with disturbances such as outdoor temperature (or weather conditions) and thermal loads. The variations of the operating point intend to vary parameters of a plant model. Thus, the HVAC control systems are extremely difficult to obtain an exact mathematical model (Kasahara 2000). Proportional-plus-integral (PI) controllers have been by far the most common control strategy as the complexity of the control problem increased (Astrom 1995). Today, a variable air volume (VAV) system has been universally accepted as means of achieving energy efficient and comfortable building environment. While the VAV control strategies provide a high quality environment for building occupants, the VAV system analysis rarely receives the attention it deserves. As a result, basic control strategies for the VAV system have remained unchanged up to now (Hartman 2003). In addition, applying the model predictive control method to the HVAC systems, the control performance has been highly improved by pursuing the deviation from the operating point (Taira 2004). According to this report, recognizing the deviation from the operating point and calculating the optimal control inputs about the newly obtained operating point on next sampling time, the control system gives better responses than the traditional feedback control system. Motivated by these considerations in these reports, we consider the room temperature and humidity controls using the adjustable resets which compensate for thermal loads upsets. One of the primary objectives of the HVAC systems is to maintain the room air temperature and humidity at the setpoint values to a high quality environment for building occupants. The room temperature and humidity control systems may be represented in the same blockdiagram form as single-variable, single-loop feedback control systems because this interaction is weak relative to the desired control performance.

Analysis of a gyroscopic force measuring system in three-dimensional space

Abstract This paper concerns the development of an entirely new sensor for measuring forces using a gyroscope (called gyroscopic force measuring system, or simply GFMS) for measuring a force vectorially. In a previous paper [S. Kurosu, M. Adachi, K. Kamimura, Dynamical characteristics of gyroscopic weight measuring device, ASME J. Dynamic System Measurement, and Control 119 (1997) 346–350], the dynamics of the GFMS for measuring a vertical force were investigated and the principal characteristics were examined theoretically and experimentally. The results of this work are directly applicable to measurement of a vectorial force in three-dimensional space. The principle and the dynamical characteristics of the GFMS for measuring a force vector are analyzed theoretically. To measure a force vectorially, two auxiliary turntables (driven by servomechanisms) are installed around the gyroscope, in which turntable outputs are required to follow some angles of incidence of a force vector. Some unfavorable errors caused by various factors and disturbances are analyzed. Two types of compensation methods are proposed as a device both for accurate force measurement and disturbance suppression. The feasibility of the proposed GFMS is confirmed by numerical simulations.

Length measurement of moving products on conveyor belt (2nd report)

The goal of our study is to present an entirely new method which achieves higher speed of operation and highly accurate length measurement of products on a conveyor belt. We propose to measure the length of products with a digital image taken by a digital camera. We discuss some technical problems to estimate the length of products with high accuracy. In this paper, we demonstrate the length established by using 4 kinds of the calibration formulas from data obtained. As the result, the length measurement of all products by using the calibration formula derived from data of the 4th row can be satisfied with the required accuracy.