Abstract: A mechanical manipulator which includes fingers under the control of a computer, antenna sensing means mounted on such fingers and extended and retracted from the fingers under the control of the computer, means for detecting the contact or proximity of the extended antenna sensing means with a workpiece, means responsive to the antenna sensing means for retracting the sensing means from interference with the workpiece and for adjusting the control of the fingers. The fingers are adapted for X, Y and Z linear motions and provides pitch, yaw and roll angular motion. The retractable antenna sensing means resembles a whisker which extends from the finger and makes contact with or approaches the workpiece. The antenna sensing means may include a retractable pneumatic back pressure sensor via the back pressure of a fluid in the supply, created when the fluid impinges on the workpiece. The retractable antenna whisker bends more readily than the rigid finger.