Visual servoing
Visual servoing, also known as vision-based robot control and abbreviated VS, is a technique which uses feedback information extracted from a vision sensor (visual feedback) to control the motion of a robot. One of the earliest papers that talks about visual servoing was from the SRI International Labs in 1979.
Visual servoing taxonomy
There are two fundamental configurations of the robot end-effector (hand) and the camera:
Eye-in-hand, or end-point closed-loop control, where the camera is attached to the moving hand and observing the relative position of the target.
Hand to eye, or end-point open-loop control, where the camera is fixed in the world and observing the target and the motion of the hand.
Visual Servoing control techniques are broadly classified into the following types:
Image-based (IBVS)
Position/pose-based (PBVS)
Hybrid approach
IBVS was proposed by Weiss and Sanderson. The control law is based on the error between current and desired features on the image plane, and does not involve any estimate of the pose of the target. The features may be the coordinates of visual features, lines or moments of regions. IBVS has difficulties with motions very large rotations, which has come to be called camera retreat.
