A new technique for fully autonomous and efficient 3D robotics hand/eye calibration

Abstract

This paper describes a new technique for computing 3D position and orientation of a camera relative to the last joint of a robot manipulator in an eye-on-hand configuration. This is part of a trio for real-time 3D robotics eye, eye-to-hand, and hand calibrations, which use a common setup and calibration object, common coordinate systems, matrices, vectors, symbols, and operations throughout the trio, and is especially suited to machine vision community. It is easier and faster than any of the existing techniques, and is ten times more accurate in rotation than any existing technique using standard resolution cameras, and equal to the state-of-the-art vision based technique in terms of linear accuracy. The robot makes a series of automatically planned movements with a camera rigidly mounted at the gripper. At the end of each move, it takes a total of 90 ms to grab an image, extract image feature coordinates, and perform camera extrinsic calibration. After the robot finishes all the movements, it takes only a few milliseconds to do the calibration. A series of generic geometric properties or lemmas are presented, leading to the derivation of the final algorithms, which are aimed at simplicity, efficiency, and accuracy while giving ample geometric and algebraic insights. Besides describing the new technique, critical factors influencing the accuracy are analyzed, and procedures for improving accuracy are introduced. Test results of both simulation and real experiments on an IBM Cartesian robot are reported and analyzed. 1) Camera Calibration (see [6], [ 101, [ 1 11, [ 131). 2) Robot Eye-to-Hand Calibration (this paper). 3) Cartesian Robot Hand Calibration [5].

Fully Automatic Endoscope Calibration for Intraoperative Use

“…We can establish an equation of the type A · X = X · B where X is the transformation between the marker and the camera, A is the movement of the marker relative to the tracking device A = j H world marker · i H marker world and B is the camera motion relative to the calibration grid frame B = j H grid cam · i H cam grid . A similar problem exists in the robotics community, where the calibration between a robot's end-effector and a camera attached to it is known as Hand-Eye calibration [6], [7], [8], [9].…”

“…The Hand-Eye calibration was performed using [6] and the error has been measured by backprojecting the 3D grid points computed in the tracker coordinate system. In our setup the marker was positioned 150 mm from the tip of the endoscope.…”

Epipolar Geometry for Humanoid Robotic Heads

“…All variables subscripted Enc will be with respect to the current encoder reading. Compute updated V 1,Enc , V 2,Enc by Equation 11.…”

“…Such systems include cameras mounted on robotic arms, often referred to as hand cameras, and also in the heads of humanoid robots, such as our upper-torso humanoid infant, Nico, which is discussed in more depth in Section 5.1. The desire to calibrate the position of the cameras relative to the underlying robotic platform has given rise to two tasks, hand-eye and head-eye calibration, which either describe solving for how a camera is mounted with respect to a movable platform, usually with known kinematics, or solving for its position in space with respect to a manipulator, [7][8] [9][10] [11]. Kinematic calibration is the process of estimating the kinematics of the underlying system, [12] [13].…”

Monitoring Critical Points in Robot Operations with an Artificial Vision System

“…In common applications the presence of approximately straight lines is usual. The Galilean relativity allows the application of this algorithm both to a moving camera (for instance in a robot hand-eye configuration [1][2] or ego-docking [3] for autonomous robot or vehicle navigation [4][5]) and to a fixed camera observing a moving object. Some examples of the latter are: − robot gripper obstacle avoidance [6] or objects localisation and catching; − in the case of autonomous navigation the so called echo-docking.…”