Abstract: A method and apparatus for guiding a driverless vehicle along a path defined by a guide cable carrying a current in a horizontal road surface includes mounting a first coil, having a major coil axis, at +45 degrees relative to the horizontal on said vehicle, mounting a second coil, having a major coil axis, at -45 degrees relative to the horizontal on said vehicle such that the axes of said first and second coils intersect, sensing both the radial and circular field vectors of the electromagnetic field with each coil, comparing the magnitude of the radial vector with the magnitude of the circular vector for each coil whereby the lateral position of the intersection point of the axes of the coils is determined relative to the guide cable to indicate the lateral displacement of the vehicle relative to said path, and using the displacement information in the vehicle steering system.

Abstract: The cam switch mechanism which is particularly appropriate for use in a pullkey where one must be able to initiate two separate switching operations, i.e. lockout and signal, enables a pull on a wire at either end of the unit to trigger a first response, e.g. lockout, but still permits further pulls on the wire to trigger repeated second responses, e.g. signal. First and second microswitches are actuated via independent cam followers whose movement is controlled by linear sliding cams connected respectively to the pullwires at opposite ends of the unit. Each cam comprises two parallel cam plates with the four plates interleaved so that recessed zones in the plates control movement of the cam followers. A manually controllable actuator, such as a lockout knob, may be provided to actuate the first microswitch independently of the movement of the linear cams without inhibiting subsequent sliding movement of the linear cams.