= End effector
An <end effector> is the device at a <robot arm>'s working end that directly performs its task: for example, a gripper, welding tool or suction cup. The arm places and orients it, while the tool's geometry and contact behavior determine how that motion affects the object. A tool-tip frame can differ from the mounting-flange frame, so its offset must be included in <forward kinematics>.<Modern Robotics: Mechanics, Planning, and Control by Kevin M. Lynch and Frank C. Park>[Chapter 4, author supplement §4.1.1, end-effector frame and configuration]{ref}
For example, suppose a two-finger gripper holds an object vertically by dry <friction>. If each finger applies normal <force> $N$ and the <coefficient of friction> is $\mu$, the ideal upward friction capacity is $2\mu N$. With $\mu=0.5$ and $N=10\,\mathrm N$ per finger, that capacity is $10\,\mathrm N$, just above the weight of a one-kilogram object near Earth's surface. A real test varies gripping force and load while observing slip; contact material, deformation and acceleration can invalidate the simple estimate. Positioning accuracy alone therefore does not establish grasp reliability.
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