Appeal No. 96-2194
Application 08/042,292
detector holders 8 and 9 are all mounted on rotary plate 14,
which is rotated by driving mechanism 15 so as to move the pole
shoes and detectors around the end portion 2 of tubular body 1,
which remains stationary (col. 4, lines 28-32).
Houskamp discloses several different types of guidance
systems for controlling the path of a self-propelled vehicle.
Among the prior art systems described are an optical system using
fluorescent markings on the floor (col. 1, lines 25-30) and
magnetic field systems using buried conductors carrying AC
currents (col. 1, line 43 to col. 2, line 38; col. 4, line 66 to
col. 7, line 10; Figs. 3-7). According to Houskamp, buried
conductor magnetic field systems have a number of disadvantages.
The first, which is dictated by the fact that the guide path must
be formed as a current carrying conductor, is the need to use a
relatively low resistance material such as solid or stranded
wire, which does not stretch appreciably and thus can break due
to flexing of floor sections (col. 2, lines 43-51). Another
problem is that the wire may be subject to the corrosive effects
of industrial chemicals or chemicals contained in the floor
material itself (col. 2, lines 51-65). Still another problem,
which is due to the need for closed current paths, is that each
path segment in a multiple path system must be formed of only
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Last modified: November 3, 2007