Yoshikazu Suematsu

A wide angle vision sensor with high distortion lens-detection of camera location and gaze direction based on two-parallel-line algorithm

The authors have conducted research into a vision sensor system which is functionally similar to the human eye. We have designed and manufactured a special lens to realize this function. The lens system provides an extensive 120 degree visual field, optically enlarging the image in the central area and compressing it in the peripheral area. In this paper, the authors propose a new method to detect a cameras location and gaze direction based on two parallel boundary lines of a road projected in the peripheral area, and show that it works precisely and efficiently. Subsequently, we apply this method to a curved road and compare the location detected from the boundary lines with the actual camera location, establishing that there is reasonable agreement between the two.

An advanced vision sensor with fovea

A novel concept of a vision sensor with a fovea is presented, and the possibility of its application for online machine control is demonstrated. This sensor is designed to approximate the visual mechanism of the human eye, which has a fovea (high-resolution attention zone) in its field of view and executes the necessary movements of the viewpoint. The vision sensor consists of a conventional matrix charge-coupled device (CCD) camera and a distortion lens that enlarges the image in the fovea and compresses the one in the peripheral zone. The process of image recognition is simulated by computer. The results show that the proposed sensor serves to significantly reduce the amount of information required per scene.<<ETX>>

Development of a High-Speed on/off Digital Valve for Hydraulic Control Systems using a Multilayered PZT Actuator

Abstract In this study, a high-speed on/off digital valve was developed for use in a hydraulic control system. The device basically consists of a poppet valve acting as the main valve, and a multilayered piezoelectric (PZT) actuator for driving the poppet valve. A hydraulic amplifier was adopted to increase the actuation of the PZT actuator to the poppet valve. A compensation mechanism was set up to reduce this temperature effect in the hydraulic actuation of the PZT actuator. This problem arises when the oil temperature increases and causes the valve displacement to fluctuate slightly. The static and dynamic characteristics of the device were investigated by experiment and computer simulation. As a result, it was found that the switching time of the valve is less than 0.7 ms. Moreover, the valve can be driven by a PWM carrier wave using frequencies of up to 500 Hz. Additionally, the validity of the temperature compensation mechanism was confirmed. Hence, this valve may be determined as feasible device to be used in hydraulic systems.

Recognition of traffic marks in the images of WAHD lens by using color information and neural networks

In their laboratory, the authors have conducted research into a special super wide angle with high distortion lens (WAHD lens) which is designed to be functionally similar to the human eye. By using this lens, they optically obtain foveated information (distorted image). Color information and neural networks are used to make a computer recognize the traffic marks from the distorted image. This paper describes a color characteristic compensation method for the image obtained by WAHD lens, and a feature generation method based on discrete cosine transformation (DCT). The features are used in backpropagation trained neural networks. They conclude that this approach can be used in robots provided with wide angle vision sensors with high distortion lens to recognize traffic markings effectively.

Autonomous Mobile Robot Navigation based on Wide Angle Vision Sensor with Fovea

This paper examines the Wide Angle Foveated Vision Sensor (WAFVS) with a special optical system designed by mimicking a human eye and has advanced it to a parallel processing system by plural computers with multi-task operation system (OS) under LAN network to make the most of its characteristics. WAFVS system carries out parallel image processing flexibly by plural computers with multi-task OS, based on timely task distributing. This system is applied to a navigation system for an autonomous mobile robot. As an example of the execution, experiments of navigation are carried out to obtain an image with sufficient resolution for face recognition, while a camera gazes at and tracks a human face by a proposed method characterized by WAFVS. In this method, central vision using color information, and peripheral vision using object motion information from gray scale images are combined cooperatively.

Wide-Angle Vision Sensor with High-Distortion Lens. Detection of Camera Location and Gaze Direction Based on the Two-Parallel-Line Algorithm.

The authors have conducted research into a vision sensor system which is functionally similar to the human eye. We have designed and manufactured a special lens to realize this function. The lens system provides an extensive 120-degree visual field, by optically enlarging the image in the central area and compressing it in the peripheral area. In this paper, the authors propose a new method to detect a cameras location and gazing direction based on two parallel boundary lines of a road projected in the peripheral area, and show that it works precisely and efficiently. Subsequently, we apply this method to a curved road and compare the location detected from the boundary lines with the actual camera location, and establish that there is reasonable agreement between the two.

Control of a flexible inverted pendulum

This study treats the control problem of an inverted pendulum with a flexible structure. Controlling an inverted pendulum is a fundamental of stabilizing unstable systems such as walking robots. Furthermore, consideration of the flexibility is essential for controlling light-weight mechanical systems with quick motion. The controlled system in this study consists of a wire-driven carrier, a flexible beam hinged to the carrier, and a weight fixed on the other side of the beam. Linear quadratic control was applied to the system using a personal computer, but resulted in a steady vibration due to the Coulomb friction. The characteristics of the relaxation-type vibration were well explained by the analysis using the method of averaging. A simple recursive algorithm was employed to estimate the amount of Coulomb friction. With on-line estimation and compensation of the friction, linear quadratic control was successfully applied to stabilizing the system.

Oscillating Phenomena of a Jet in a Jet-edge System : 1st Report, Behavior and Frequency of an Oscillating Jet

A two-dimensional jet begins to oscillate in transverse direction when it impinges on a wedge-shaped object. This is well known as the edge-tone phenomenon, and many experimental and theoretical studies have been made for a long time. Nevertheless, the mechanism of determination of the oscillating frequency which is one of the most fundamental properties of the edge-tone phenomenon is not clarified yet. In this investigation, the behavior of the oscillating jet and thee mechanism of determination of the oscillating frequency are studied experimentally and a theoretical model which explains these phenomena is proposed. And the propriety of this model is verified by comparison of experimental and theoretical results about the oscillating frequency and the shapes of the streak lines of the oscillating jet.

A Study on a Fluidic Oscillator with Feedback Tubes : Nonmemory Bistable Fluid Amplifier Oscillator

In this report is studied a fluidic oscillator, made of a nonmemory bistable amplifier, with loads and feedback tubes. A mathematical model for describing approximately the performance of the oscillator is presented. Analytical results derived from the model are examined by experiments. The results obtained are summarized as follows : (1) The model explains the performance of the oscillator fairly well. And the relation between performance and geometry of the oscillator is clarified. (2) Analytical results concerning the condition for sustained oscillation and the frequency of the oscillation show good agreement with experimental data.

A Study on a Bistable Fluid Amplifier Load Oscillator : 2nd Report, A Mathematical Model for the Oscillator

This paper presents the experimental results on bistable fluid amplifier characteristics and checks its representation which was introduced in the previous report. Then a mathematical model for a fluidic load oscillator is presented. And the analytical results derived from the model are compared with the experimental data. The results obtained are summarized as follows : (1) Experimental results show that the representation of the bistable fluid amplifiers characteristics given in the previous report is favorable. (2) The mathematical model well explains the features of the sustained oscillations occurring in the fluidic load oscillator. (3) The model also well explains the relation between the sustained oscillations in the system and the natural oscillations. Furthermore, the experimental data of the fluidic load oscillation are given for a wide Reynolds number range.