a robot for guiding movements has its power provided by an operator who handles a tool integral with the robot . like a conventional robot , the guiding robot has several axes respectively associated with rotation sensors that are connected to a computer system memorizing a path to be followed . when the operator moves the tool beyond the stored path , blocking devices , controlled by the computer system and replacing the robot &# 39 ; s motors , prevent the tool from continuing to depart from the path . thus , at any time , the operator can move the tool within the stored path only . the blocking devices are passive , that is , they are such that they can only resist to a movement but cannot generate a movement , which prevents the occurrence of any uncontrolled movement .