Lizardo Pari

Uncalibrated visual servoing using the fundamental matrix

This paper describes a new algorithm for visual control of an uncalibrated 3 DOF joint system, using two weakly calibrated fixed cameras. The algorithm estimates on-line the Image Jacobian, a matrix which linearly relates joint velocity and image feature velocity. In our experiments we prove that by using the fundamental matrix, robustness of the estimation in the presence of noise is significantly increased with respect to already existing algorithms in specialized literature.

Vision-Based Control of the RoboTenis System

In this paper a visual servoing architecture based on a parallel robot for the tracking of faster moving objects with unknown trajectories is proposed. The control strategy is based on the prediction of the future position and velocity of the moving object. The synthesis of the predictive control law is based on the compensation of the delay introduced by the vision system. Demonstrating by experiments, the high-speed parallel robot system has good performance in the implementation of visual control strategies with high temporary requirements.

A new method for the estimation of the image jacobian for the control of an uncalibrated joint system

This paper describes various innovative algorithms for the on-line estimation of the image jacobian, a matrix which linearly relates joint velocity and image feature velocity. We have applied them successfully to the static visual control of an uncalibrated 3 DOF joint system, using two weakly calibrated fixed cameras. The proposed algorithms prove to be particularly robust when image features are calculated with an average level of noise, and our results are clearly better than those obtained for already existing algorithms in specialized literature.

Image based visual servoing: a new method for the estimation of the image jacobian in dynamic environments

This paper describes a innovative algorithm for the on-line estimation of the image jacobian based on previous movements. It has been utilized for the tracking of an uncalibrated 3 DOF joint system, using two weakly calibrated fixed cameras. The algorithm incorporates the epipolar restriction of the two cameras conveyed in the fundamental matrix, and a reliability factor has been defined for the previous movements. The tests carried out show that the proposed algorithm is more robust in presence of noise than those obtained from already existing algorithms in specialized literature.

Image Based Visual Servoing: Estimated Image Jacobian by Using Fundamental Matrix VS Analytic Jacobian

This paper describes a comparative study of performance between the estimated image Jacobian that come from taking into account the geometry epipolar of a system of two cameras, and the well known analytic image Jacobian that is utilized for most applications in visual servoing. Image Based Visual Servoing architecture is used for controlling a 3 d.o.f. articular system using two cameras in eye to hand configuration. Tests in static and dynamic cases were carried out, and showed that the performance of estimated Jacobian by using the properties of the epipolar geometry is such as good and robust against noise as the analytic Jacobian. This fact is considered as an advantage because the estimated Jacobian does not need laborious previous work prior the control task in contrast to the analytic Jacobian does.

A comparative study between analytic and estimated image Jacobian by using a stereoscopic system of cameras

This paper describes a comparative study of performance between the estimated image Jacobian that come from taking into account the epipolar geometry in a system of two cameras, and the well known analytic image Jacobian that is utilized for most applications in visual servoing. Image Based Visual Servoing architecture is used for controlling a 3 DOF articular system using two cameras in eye to hand configuration. Tests in static and dynamic cases were carried out, and showed that the performance of estimated Jacobian by using the properties of the epipolar geometry is such as good and robust against noise as the analytic Jacobian. This fact is considered as an advantage because the estimated Jacobian does not need laborious previous work prior to control task in contrast to the analytic Jacobian does.

High-speed Visual Servoing of PKMs

In this paper a visual servoing architecture based on a parallel robot for the tracking of faster moving objects with unknown trajectories is proposed. The control strategy is based on the prediction of the future position and velocity of the moving object. The synthesis of the predictive control law is based on the compensation of the delay introduced by the vision system. Demonstrating by experiments, the high-speed parallel robot system has good performance in the implementation of visual control strategies with high temporary requirements.

Homography-Based Tracking Control for Mobile Robots

This work presents a control strategy that allows a follower robot to track a target vehicle moving along an unknown trajectory with unknown velocity. It uses only artificial vision to establish both the robots position and orientation relative to the target. The control system is proved to be asymptotically stable at the equilibrium point, which corresponds to the navigation objective. Experimental results with two robots, a leader and a follower, are included to show the performance of the proposed vision-based tracking control system.

Homography-Based Tracking Control for Mobile Robot

This work presents a control strategy that allows a follower robot to track a target vehicle moving along an unknown trajectory with unknown velocity. It uses only artificial vision to establish both the robots position and orientation relative to the target, so as to maintain a specified formation at a given distance. The control system is proved to be asymptotically stable at the equilibrium point, which corresponds to the navigation objective. Experimental results with two robots, a leader and a follower, are included to show the performance of the proposed vision-based tracking control system.

Image Base Visual Servoing: Estimation of the image Jacobian by using lines in a stereo vision system

This paper describes an Image Based Visual Servoing scheme for controlling a 3 DOF robot, using a system with two cameras in eye to hand configuration. Two methods of estimating image Jacobian on line by using lines as image features are proposed. The first one takes into account both the advantages of Plu¿cker representation and properties of the stereo vision system to obtain depth sensitivity of the observed 3D lines. The second one considers direct measurements of line features in the image of an uncalibrated system. A proportional control law based on the pseudoinverse of the image Jacobian is utilized to control the task. Experimental tests have been carried out to validate the proposed methods, and extended to the analytic image Jacobian from the literature.