Nozomu Araki

Implementation of performance-adaptive PI control on a weigh feeder

In the design of a weigh feeder control system, proportional and integral (PI) control is widely employed because parameter tuning is easy and the control parameter can be intuitively understood. Hence, it is desirable to achieve high control performance using PI control rather than advanced control methods. In this study, the control parameters of the PI control system are designed on the basis of generalised minimum variance control (GMVC), and the weighting parameter for the control deviation is adaptively updated according to the control performance. Because GMVC-based PI control is based on control performance, this method can be easily adopted in industry. Both the simulation and the experimental results demonstrate the effectiveness of the GMVC-based PI control.

Design and Experimental Evaluation of a Performance-Driven Adaptive Controller

Abstract In the petroleum and refinery industry, it is necessary to establish the performance-driven control strategy in order to improve productivity (where the control performance is first evaluated and then the controller is re-designed). This paper describes a design scheme of performance-driven controllers which are based on the control mechanism described above. The proposed control scheme is simulated and its performance is numerically examined. Also, the proposed method is applied to the weigh feeder and the control results are shown.

Control of container crane by binary input using Mixed Logical Dynamical system

This paper proposes an effective control system for a container crane that takes into account disturbances such as a wind. For efficient crane operation, it is necessary to realize accurate positioning of cranes, to minimize oscillation of containers and to realize the fastest possible control time while they are being carried. The crane input is assumed to be a binary with maximum and minimum values for quick control. The entire crane system including the binary input is considered as a hybrid system. A hybrid system is a generic term for a system in which continuous and discrete dynamics exist together. We control the entire crane system using the mixed logical dynamical (MLD) system. An MLD system, which is a representation method for a hybrid system, is used for the crane system. It is generally known that an MLD system can be controlled by Model Predictive Control (MPC). We confirm the effectiveness of the proposed technique through computer simulation of the crane.

Development of bi-axial tensile tester to investigate yield locus for aluminum film under multi-axial stresses

This paper describes novel biaxial tensile test technique for a film specimen to investigate material responses to uniaxial and biaxial tensile forces. We have developed biaxial tensile tester that consists of four sets of actuator, load cell, and displacement meter in order to apply an arbitrary amount of tensile force to a film specimen in each axis. With the uniaxial test specimen of sputtered Al film, average Youngs modulus of 35 GPa and yield strength of 115 MPa have been obtained. With the biaxial test specimen, evaluation of the yield locus for Al film has carried out by applying biaxial stresses with various strain rate ratios. The obtained yield stresses could be fitted by the yield criterion based on Logan-Hosford equation. This indicates that the flow stress under biaxial stress condition differ from that under uniaxial condition. Information about the yield locus would be useful for the structural design of MEMS including Al film structures subjected to biaxial stresses.

Optimum integrated design of mechanical structure/controller using bargaining game theory

We present that the application of the Nash bargaining model, which is a solution method in the bargaining game theory, to setting the utility function for integrated design which has some design purposes. The bargaining game theory is often introduced to explain situations in economic activity, but it is also applicable to engineering problem. Applying the Nash bargaining model to integrated design problem, each design purposepsilas index is mapped into utility functions defined by design parameters, and the utility function for integrated design is easily constructed by the utility functions of each purposepsilas index. Using this method, the design problem shift into the optimum problem, which means to find the maximum problem. However, it is difficult to find the maximum of the utility function analytically. To deal with this difficulty, we use extremum seeking studied by Krstic to find the maximum of the utility function. As a design example, we design mass-damper-spring system with proportional-integral controller and verify the effectiveness of our integrated design method.

Slope-Walking of a Biped Robot with K Nearest Neighbor method

This paper proposes a walking pattern generation method with K Nearest Neighbors (K-NN) so that a bipedal walking robot can walk with compensation for environmental changes. We make up some walking path, and save them to a database, before the robot walks on slope. And we select a walking path for a suitable condition. When the robot walks on slope, we save the measured walking path to the database. Herewith, the robot has a learning function and can cope with environmental change. The proposed controller is examined and evaluated from simulations. The walking of the robot is simulated by using the proposed method, and its effectiveness is verified.

Vehicle's Orientation Measurement Method by Single-Camera Image Using Known-Shaped Planar Object

This paper describes the development of a vehicles orientation measurement system using a single camera. We applied a single camera calibration method using a planar pattern to measure the orientation from the camera to a planar object. With this technique, the orientation from camera to planar object can be obtained when using feature coordinates of more than 4 points on a planar object image. We thus proposed a method for measuring a vehicles orientation. The license plate, which is of a standard size, is used as the planar object. Its corner points are tracked by an active contour tracking method. The effectiveness of our proposed method has been verified through experiments using real vehicle images.

A robot prosthetic finger system based on finger joint angle estimation using EMG signals

The goal of this study was to develop a robot prosthetic hand system for an amputee that estimates his desired finger angle from neural signals, and operates with the motion he intends. Consequently, we considered a method for estimating finger joint angle from biosignals. We have previously proposed a finger joint angle estimation method based on surface electromyography (EMG) signals and a linear model. This method was based on a histogram of EMG signals, and may be applicable to surface EMG signals as well as neural signals. To confirm this, we carried out finger joint angle estimation experiments using both surface EMG signals and needle EMG signals measured at deep layers of muscles and are similar to neural signals. Moreover, an artificial finger robot has been designed and developed for finger amputation patients. This finger robot has 2-DOF and each joint is worked with motors and cables. The joint angles are controlled by a PID method. Using this robot and applying our proposed finger joint angle estimation method, we carried out experiments in which the robot is synchronised with the subject’s third finger motion. As a result, it was confirmed that our system is technically feasible for application to a real prosthetic hand system.

Development of High Speed Controller of Container Crane by Binary Input Using Mixed Logical Dynamical System

This paper proposes an effective control system for a container crane. For efficient crane operation, it is necessary to realize accurate positioning of the crane, to minimize oscillation of containers and to realize the fastest possible control time while they are being carried. The crane input is assumed to be binary, with maximum and minimum values for quick control. The entire crane system including the binary input is considered as a hybrid system. A hybrid system is a generic term for a system in which continuous and discrete dynamics exist together. We control the entire crane system using the Mixed Logical Dynamical (MLD) system, which is a representation method for a hybrid system. It is generally known that an MLD system can be controlled by Model Predictive Control (MPC). We confirm the effectiveness of the proposed technique through an experiment using a crane model.

Positioning Control of a 2-Mass Spring System with Static and Kinetic Friction Using Hybrid Controller

This paper proposes a new hybrid controller for a 2-mass spring system with stick-slip motion. The 2-mass spring system is considered as a hybrid system with two states: a static friction state and a kinetic friction state. In controller design, the hybrid system is described as a piecewise affine (PWA) system, which is one of the modeling frameworks of hybrid systems. It is known that the model predictive control method is applicable to PWA systems. The effectiveness of the controller has been evaluated by computer simulations.