Effector crew of an apparatus for locating a useful part of a tool

The invention relates to an effector (1, 100) comprising a support (2, 102); a connecting member (3, 103) for mechanically connecting the support (2, 102) to a tool holder (4, 104), the connecting member (3, 103) comprising a string of elements (5, 6, 101, 105,106) which are articulated to one another in such a way that a working part (8, 108) of a tool (7, 107) carried by the tool holder (4, 104) is always located in a focal region extending around a focal point (F) that is fixed with respect to the support; a locating device for at least estimating a distance (h) between the working part (8, 108) of the tool (7, 107) and an obstacle (11, 111) in a given direction of measurement, the locating device comprising a measurement sensor (9, 109) that generates a signal indicative of said distance (h). According to the invention, the sensor is secured to the effector (1, 100) and is arranged thereon in such a way that a line of sight of the sensor (9, 109) corresponding to said measurement direction passes more or less through the focal point (F). The invention also relates to a robot fitted with such an effector.