Teach by zooming: A unified approach to visual servo control (original) (raw)
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Teach by Zooming Visual Servo Control for an Uncalibrated Camera System
AIAA Guidance, Navigation, and Control Conference and Exhibit, 2005
The teach by showing approach is formulated as the desire to position/orient a camera based on a reference image obtained by a priori positioning the same camera in the desired location. A new strategy is required for applications where the camera can not be a priori positioned to the desired position/orientation. In this paper, a "teach by zooming" approach is proposed where the objective is to position/orient a camera based on a reference image obtained by another camera. For example, a fixed camera providing a global view of an object can zoom in on an object and record a desired image for an on-board camera (e.g., a satellite providing a goal image for an image-guided unmanned vehicle). A controller is designed to regulate the image features acquired by an on-board camera to the corresponding image feature coordinates in the desired image acquired by the fixed camera. The controller is developed based on the assumption that parametric uncertainty exists in the camera calibration since precise values for these parameters are difficult to obtain in practice. Simulation results demonstrate the performance of the developed controller.
Adaptive Visual Servoing by Simultaneous Camera Calibration
Proceedings 2007 IEEE International Conference on Robotics and Automation, 2007
Calibration techniques allow the estimation of the intrinsic parameters of a camera. This paper describes an adaptive visual servoing scheme which employs the visual data measured during the task to determine the camera intrinsic parameters. This approach is based on the virtual visual servoing approach. However, in order to increase the robustness of the calibration several aspects have been introduced in this approach with respect to the previous developed virtual visual servoing systems. Furthermore, the system is able to determine the value of the intrinsic parameters when they vary during the task. This approach has been tested using an eye-in-hand robotic system. 1
Graphic simulation for camera calibration in visual-servoing applications
Proceedings of the 8th conference on Signal …, 2008
Graphic Simulation for Camera Calibration in Visual-Servoing Applications DORIAN COJOCARU*, RĂZVAN TUDOR TĂNASIE** * Mechatronics Department, ** Software Engineering Department University of Craiova Bvd. Decebal, Nr. 107, 200440, Craiova, Dolj ROMANIA ...
Adaptive visual servoing in the presence of intrinsic calibration uncertainty
2003
Abstract In this paper, we design an adaptive kinematic controller that asymptotically regulates a robot end-effector to a desired position and orientation under visual feedback (of points located on a fixed reference frame) from a camera mounted on the end-effector. This task is accomplished despite lack of depth measurements as well as uncertainty in the camera intrinsic parameter matrix.
A Visual Servoing-Based Method for ProCam Systems Calibration
Sensors, 2013
Projector-camera systems are currently used in a wide field of applications, such as 3D reconstruction and augmented reality, and can provide accurate measurements, depending on the configuration and calibration. Frequently, the calibration task is divided into two steps: camera calibration followed by projector calibration. The latter still poses certain problems that are not easy to solve, such as the difficulty in obtaining a set of 2D-3D points to compute the projection matrix between the projector and the world. Existing methods are either not sufficiently accurate or not flexible. We propose an easy and automatic method to calibrate such systems that consists in projecting a calibration pattern and superimposing it automatically on a known printed pattern. The projected pattern is provided by a virtual camera observing a virtual pattern in an OpenGL model. The projector displays what the virtual camera visualizes. Thus, the projected pattern can be controlled and superimposed on the printed one with the aid of visual servoing. Our experimental results compare favorably with those of other methods considering both usability and accuracy.
Visual Servoing Invariant to Changes in Camera-Intrinsic Parameters
IEEE Transactions on Robotics and Automation, 2004
This paper presents a new visual servoing scheme which is invariant to changes in camera intrinsic parameters. Current visual servoing techniques are based on the learning of a reference image with the same camera used during the servoing. With the new method it is possible to position a camera (with eventually varying intrinsic parameters), with respect to a non-planar object, given a "reference image" taken with a completely different camera. The necessary and sufficient conditions for the local asymptotic stability show that the control law is robust in the presence of large calibration errors. Local stability implies that the system can accurately track a path in the invariant space. The path can be chosen such that the camera follows a straight line in the Cartesian space. Simple sufficient conditions are given in order to keep the tracking error bounded. This promising approach has been successfully tested with an eye-in-hand robotic system.
2003
Abstract In recent papers, a new class of model-free (ie, the 3-dimensional task-space model of the object is unknown) visual servoing methods was proposed that are based on the estimation of the relative camera orientation between two views of an object. By utilizing homography-based techniques, the control problem is decoupled by separating the rotation and translation components. A single controller is used to control the rotation component, and the class members consist of various translation controllers.
Volumetric Calibration of Stereo Camera in Visual Servo Based Robot Control
The primary objective of the paper is to propose a calibration method for a stereo camera used in a visual servo control for a robot manipulator. Specifically, projection matrix between the stereo camera and world coordinates is established using few calibration points and solved using the single value decomposition technique. Then calibration accuracy is compared for a randomized and designed set of points, and economical number of calibration points is recommended. Additionally, the non-linear lens distortion is modeled and corrected to improve the accuracy. In addition, this research focuses on the development and implementation of a fully automated visual servo control system using a stereo camera that is calibrated by proposed method.
Kinematic calibration of an active camera system
Perceptual activity for exploration, probing and searching is very important in computer vision. For the purpose of intelligently controlling the sensor's motion and parameters for different sensing strategies and designated tasks in perceptual activity, an active camera system is often used. An active camera system is also usually used for vision-based guidance. In order to position the camera system accurately and to obtain the relation between the camera and the manipulator, the active camera system must be calibrated.
Camera modelling for visual servo control applications
Mathematical and Computer Modelling, 1996
When designing a visual servo system, it is important to have a complete and accurate model of the imaging process. Unmodelled imaging dynamics may play an important role in the stability and performance of such systems. In this paper, we present a detailed camera model which can be used in the design and analysis of visual servo systems. Using the free-standing acrobat as a testbed, we analyze the effects of unmodelled imaging dynamics on visual servo control systems. We show that certain camera parameters strongly influence the performance of this system, and that accurate modeling is necessary for proper selection of imaging hardware.