A modular system for robust positioning using feedback from stereo vision

Abstract

Abstract-This paper introduces a modular framework for robot motion control using stereo vision. The approach is based on a small number of generic motion control operations referred to as primitive skills. Each primitive skill uses visual feedback to enforce a specific task-space kinematic constraint between a robot end-effector and a set of target features. By observing both the end-effector and target features, primitive skills are able to position with an accuracy that is independent of errors in handeye calibration. Furthermore, primitive skills are easily combined to form more complex kinematic constraints as required by different applications. These control laws have been integrated into a system that performs tracking and control on a single processor at real-time rates. Experiments with this system have shown that it is extremely accurate, and that it is insensitive to camera calibration error. The system has been applied to a number of example problems, showing that modular, high precision, vision-based motion control is easily achieved with off-the-shelf hardware.

Visual Servoing Using Projective Kinematics

“…Therefore, it allows for global visual seroving since it is valid over the entire configuration space and allows for arbitrary shapes of the tool to be recovered on-the-fly. In contrast to existing formulations of visual servoing, the Jacobian is neither an on-line estimated linear model [7], nor an apriori given approximation around the target [8], [9]. Above that, metric-representations, which would require a-priori calibration, were successfully eliminated in favor of projective camera space and projective kinematics.…”

Motion Tracking for Minimally Invasive Robotic Surgery

“…A region-based approach, which does not need any particular kind landmarks is described in (Hager & Belhumeur, 1998). This tracking system is successfully applied in a system for robust hand-eye coordination based on images of a stereo camera (Hager, 1997). The use of stereo imaging from a stereo endoscope enables to estimate the threedimensional position of the target, which is necessary for visual servoing tasks in 3D environments.…”

Visual Feedback Using Virtual Object Points In Stereo Vision Based Manipulator

“…The scaling transformation matrix which ss, sy, and s, denote the scaling factors in x, y, and z axis, respectively, is given by equation (3). The scaling transformation applies the individual scale factors to a coordinate system.…”