Yasuhiro Ohyama

Improving Disturbance-Rejection Performance Based on an Equivalent-Input-Disturbance Approach

This paper presents a new method of improving the disturbance-rejection performance of a servo system based on the estimation of an equivalent input disturbance (EID). First, the concept of EID is defined. Next, the configuration of an improved servo system employing the new disturbance-estimation method is described. Then, a method of designing a control law employing a disturbance estimate is explained. Finally, the speed control of a rotational control system is used to demonstrate the validity of the method, and some design guidelines are presented.

Internet-Based Teaching and Experiment System for Control Engineering Course

e-Learning engineering courses with online experiments are attracting a great deal of attention because of the flexibility they provide in both teaching and learning. This paper has described an Internet-based teaching and experiment system for control engineering (ITESCE) that provides students with online course material, a simulator, an online control experiment using an arm robot, and the ability to store and search simulation and experimental results. To implement the functions required by the course and to facilitate connection to the Internet, the ITESCE is based on a standard browser/server architecture with three layers and employs multithreading, Java applets, and Java database connectivity. Background control subsystems handle the real-time control of experiments, and a network server handles communication with clients and with background control subsystems. A database stores simulation and experimental results. The course covers a variety of control methods, and students can try them out through online simulations and experiments. To enhance realism, a Web camera takes a video of an experiment and streams it to a students PC in real time.

A new approach to the estimation and rejection of disturbances in servo systems

This paper proposes a new approach to disturbance estimation based on a curvature model that improves the disturbance rejection performance of a servo system. The main feature is that the stability of the control system is guaranteed when the disturbance estimate is incorporated directly into the designed servo control law. Experimental results show that disturbances are rejected efficiently when this approach is used.

Disturbance estimation and rejection - an equivalent input disturbance estimator approach

This paper presents a new method of improving the disturbance rejection performance of a servo system by estimating an equivalent input disturbance. First, the concept of equivalent input disturbance is defined. Next, the configuration of an improved servo system employing the new disturbance estimation method is described. Then, a method of designing a control law employing the disturbance estimate is explained. Finally, the positioning control of a two-finger robot hand is used to demonstrate the validity of the method.

Estimation of Equivalent Input Disturbance Improves Vehicular Steering Control

This paper describes a simple effective approach to vehicular steering control based on the estimation of an equivalent input disturbance. A control system configuration with a disturbance estimator and a design method based on linear matrix inequalities are explained. The simulation results demonstrate the validity of the method.

Walker with hand haptic interface for spatial recognition

This paper presents a user-friendly hand force feedback system to recognize surrounding obstacles around the elderly to making walking safer. The system is implemented on a joystick mounted on a walker. The user is able to recognize the surrounding spatial information from the repulsive force generated as feedback on the joystick. The system is based on the generation of a virtual potential field that corresponds to the distance and direction to the obstacle is employed. Through the experimental results, it is found that the practice time of the user to learn basic operation of the system is sufficiently short. Furthermore, the user feels the sense of security while recognizing the surrounding information through the hand force feedback

The electric wheelchair controlled by human body motion - Design of the prototype and basic experiment -

This research develops a machinepsilas interface which has features of universal design and offers an intuitive operation for complex tasks. We set the development of interface of electric wheelchair as a practical example, and proceed with this research. The joystick is the operation interface of general electric wheelchair. The user needs to operate it in accordance with machinepsilas operational procedure specifications. Therefore the joystick is convenience operation system for the system side rather than the user side We focus on the body motions which humans have, and try to realize a new type of interface which replaces conventional joystick. The body motions is time-series data which contains ambiguousness, the common motions are extracted from this data and inputted to the electric wheelchair interface. Then the body motions are able to control the electric wheelchair. In particular this paper describes the design of the prototype and results of basic experiments.

The electric wheelchair controlled by human body motion

This research develops a machines interface which has features of universal design and offers an intuitive operation for complex tasks. We set a development of interface of electric wheelchair as a practical example, and proceed with this research. The joystick is the operation interface of general electric wheelchair. The user needs to operate it in accordance with machines operational procedure specifications. Therefore the joystick is convenience operation system for the system side rather than the user side We focus on the body motions which humans have, and try to realize a new type of interface which replaces conventional joystick. In order to measure the human body motion, we adopt the force distribution on the wheelchair. Since pressure distributions on a wheelchair appear on a seat face and a seat back, we examined which parts have strong correlation with the body motion. As a result, it turned out that pressure distribution on a seat back has strong correlation with the body motion. Based on this result, we made a prototype and did a basic experiment. For the result of basic experiment, it was confirmed that the body motion could control a wheelchair.

Stability of swarm robot based on local forces of local swarms

This paper proposes a control algorithm for a robotic swarm based on the center of gravity of the local swarm. In order to be compatible with maintaining a high stability of the whole swarm and advancing to the goal, virtual forces; local forces and an advancing force which are produced by the algorithm, are applied to multiple autonomous mobile robots. Local forces such as an attraction and a repulsion, are applied to each robot for increasing the stability of the local swarm. Overlapping each local swarm partially increases the stability of the whole swarm. The advancing force is applied to each robot for advancing to the goal while maintaining the stability of the local swarm. Since obstacles which prevent the robot advancing are considered as a disturbance from the viewpoint of the stability of the whole swarm, an effectiveness of the algorithm in obstacle space is evaluated using a dynamics simulation. As a result, it is found that the algorithm is able to maintain the high stability of the whole swarm advancing to the goal.

Cooperative interaction of walking human and distributed robot maintaining stability of swarm

This paper proposes a method of cooperative interaction that a human and distributed robots move cooperatively so as to maintain the swarm situation that robots surround the moving human. This paper is concerned with the control for maintaining the high stability of the swarm, and proposes a control algorithm for the robotic swarm in obstacle or slope space. The proposed algorithm for overcoming above problems is based on the center of gravity of the local swarm which attracts the robot to it, and is applied to the omni-directional mobile robots. It is confirmed that the effectiveness about maintaing the stability of the swarm through simulations using ODE (Open Dynamics Engine).