Visual servoing of nonholonomic cart

This paper presents a visual feedback control scheme for a nonholonomic cart without capabilities for dead reckoning. A camera is mounted on the cart and it observes cues attached on the environment. The dynamics of the cart are transformed into a coordinate system in the image plane. An image-based controller which linearizes the dynamics is proposed. Since the positions of the cues in the image plane are controlled directly, possibility of missing cues is reduced considerably. Simulations are carried out to evaluate the validity of the proposed scheme. Experiments on a radio controlled car with a CCD camera are also given</p

Potential switching control in visual servo

Stability of feature-based visual servoing controllers proposed so far is local. The initial features far from the reference may converge to features different from the reference or, even worse, they may not converge. In this paper, the stability of feature-based visual servoing is considered by using potential. The stable region is visualized and artificial potential switching is proposed to extend the stable region</p

Visual servoing with linearized observer

One of the most important problems in feature-based visual servoing is the slow sampling rate and the delay of the camera that can make the closed loop system oscillative or unstable easily. In the paper, a linearized observer that estimates the object velocity and updates the visual information with the joint sampling rate is proposed. Stability of the observer-based control system and effectiveness of the observer are verified by experiments on a PUMA 560 robot</p

Potential problems and switching control for visual servoing

This paper proposes a potential switching scheme that enlarges the stable region of feature-based visual servoing. Relay images that interpolate initial and reference image features are generated by using affine transformation. Artificial potentials defined by the relay images are patched around the reference point of the original potential to enlarge the stable region. Simulations with simplified configuration and experiments on a 6 DOF robot show the validity of the proposed control scheme</p

Performance and sensitivity in visual servoing

Describes the relationship between the control performance and the number/configuration of the image features in feature-based visual servoing. The performance is evaluated by two ways: accuracy and speed. A quantitive definition of the sensitivity is given and the relationship among the sensitivity, the speed of convergence and the accuracy are discussed by using the image Jacobian. It is proved that these performance indices are increased effectively by using a point with different height. Experiments on Puma 560 are given to show the validity of these performance measures</p

Modeling and control of robotic yo-yo with visual feedback

Yo-yo is a toy made of two thick circular pieces of wood, plastic, etc., connected with a short axle that can be made to run up and down, by moving a string tied to it. Humans can play with a yo-yo without difficulty. However, developing a robot system that can play with a yo-yo presents a significant challenge to controller design, because the dynamics of the yo-yo are difficult to model precisely. Moreover, since the dynamics are not continuous and there are integral-type constraints on the hand trajectory, conventional continuous time feedback control theory does not work well. This paper present a model and a control scheme for robotic yo-yo with visual feedback. Experiments on a PUMA 560 are carried out to evaluate the validity of the discrete dime formulation and the controller design</p

Visual servoing with redundant features

This paper presents how the control performance of the visual servo system is improved by utilizing the redundant features. We use the minimum singular value of the image Jacobian as a measure of the control accuracy (sensitivity) and we show that the sensitivity is strictly decreased by increasing the number of redundant features. Effectiveness of the control scheme with redundant features are verified by real time experiments on a PUMA 560 manipulator</p

Potential problems in visual servo

Stability of feature-based visual servo controllers proposed so far is local. The initial features far from the reference may converge to features different from the reference or even worse they may not converge. In this paper, stability of feature-based visual servo is considered by using potential. The stable region is visualized and artificial potential switching is proposed to extend the stable region</p

Enhancing the ESIM (Embedded Systems Improving Method) by Combining Information Flow Diagram with Analysis Matrix for Efficient Analysis of Unexpected Obstacles in Embedded Software

In order to improve the quality of embedded software, this paper proposes an enhancement to the ESIM (Embedded Systems Improving Method) by combining an IFD (Information Flow Diagram) with an Analysis Matrix to analyze unexpected obstacles in the software. These obstacles are difficult to predict in the software specification. Recently, embedded systems have become larger and more complicated. Theoretically therefore, the development cycle of these systems should be longer. On the contrary, in practice the cycle has been shortened. This trend in industry has resulted in the oversight of unexpected obstacles, and consequently affected the quality of embedded software. In order to prevent the oversight of unexpected obstacles, we have already proposed two methods for requirements analysis: the ESIM using an Analysis Matrix and a method that uses an IFD. In order to improve the efficiency of unexpected obstacle analysis at reasonable cost, we now enhance the ESIM by combining an IFD with an Analysis Matrix. The enhancement is studied from the following three viewpoints. First, a conceptual model comprising both the Analysis Matrix and IFD is defined. Then, a requirements analysis procedure is proposed, that uses both the Analysis Matrix and IFD, and assigns each specific role to either an expert or non-expert engineer. Finally, to confirm the effectiveness of this enhancement, we carry out a description experiment using an IFD.14th Asia-Pacific Software Engineering Conference (APSEC\u2707), 4-7 Dec. 2007, Aichi, Japa