Eyeinhand

Eyeinhand is a term used primarily in robotics and computer vision to describe a configuration where a vision sensor is mounted on the end effector (the robot's hand or gripper) rather than fixed in the workspace. The term is often written as eye-in-hand or eye in hand, but the concatenated form eyeinhand is also encountered in some sources.

In robotics, eye-in-hand enables direct visual feedback of the manipulated object and the immediate task area, improving precision in tasks such as grasping, alignment, and pose estimation. It contrasts with eye-to-hand configurations, in which the camera is stationary in the environment. Key problems include the hand-eye calibration problem, which determines the spatial relationship between the robot base, the end effector, and the camera. Typical models describe the kinematic chain with transformation matrices, solved by methods based on Tsai-Lenz, Horaud, or newer optimization-based approaches. Calibration is required for accurate 3D reconstruction, pose estimation, and control.

Advantages include high accuracy in close-quarters manipulation, robust handling in cluttered scenes, and dynamic updating of perceptual data during motion. Disadvantages encompass more complex calibration, potential occlusion by the hand, limited field of view, and sensor payload constraints. Applications span industrial manipulation, robotic-assisted surgery, microassembly, and research in active perception. The concept has influenced related fields such as hand-eye coordination in human-robot collaboration. See also: eye-to-hand, hand-eye calibration, active perception.