Abstract: The invention relates to a pneumatic prehension device or pincers constituted by a body pierced with a cylinder-forming boring inside which a piston can slide under the action of pressurized air. Two fingers are movably mounted on the body so that they can assume all of the positions found between an extreme open position and an extreme closed position. A shackle comprises a governing mechanism for opening and closing of the fingers. When it slides, the piston is capable of driving the shackle in translation so as to govern the opening or the closing of the fingers. The shackle (12) has a cylindrical head (13) provided to slide and be guided inside a bore (3), the axis of which is the same at the axis of bore (2) that receives piston (5). The shackle also comprises a coaxial rod (17) at the end of which piston (5) is assembled with radial play.

Abstract: A piston-cylinder assembly is equipped with means for determining and validating the piston position of that assembly part of a robot. A piston 1 slides axially in a cylinder 2, and moves a permanent magnet 13. The resulting magnetic field is sensed by a Hall effect transistor. A member 12 is controlled by a program of analog signals coming from the sensor. When the run of piston 1 is stopped, the position of that piston is one of the positions that have been previously determined and memorized by control member 12.