Device for precluding a collision between a mobile object and a fixed or mobile obstacle

A device for precluding a collision between a mobile object moving in a predetermined path and a second object in the same path, the mobile object including a motor, a source of power for said motor, and a means for interrupting the supply of power from said source to said motor, the device comprising a fixed tape disposed along the path and a sensor carried by the mobile object, said fixed tape comprising a track which has a band having a predetermined resistivity, the sensor comprising a series circuit having a source of voltage, a limit switch comprising the means for interrupting the supply of power, and a wiping means for electrically contacting the band so as to connect said band in series in said circuit, said limit switch interrupting said supply of power from said source to said motor when the resistance presented in said series circuit by said band is reduced to a predetermined value.