Magnetic object detecting system for automated guided vehicle system

• US 4,800,978 A
• Filed: 11/08/1985
• Issued: 01/31/1989
• Est. Priority Date: 11/09/1984
• Status: Expired due to Term

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Wasa, Yasuhiro, Miura, Tokuki, Kondo, Yojiro
• Primary Examiner(s): Mitchell, David M.
• Assistant Examiner(s): Culbreth, Eric
• Application Number:
  US06/796,209
• Time in Patent Office: 1,180 Days
• Field of Search: 180/168, 180/169, 318/38, 318/567, 318/687, 318/587, 318/135, 318/568, 318/580, 318/576, 340/904, 340/905, 340/933, 340/941, 324/207, 324/208, 324/251, 324/173, 324/174, 336/117-119, 336/129, 336/132, 336/133, 310/12, 310/15, 104/284, 104/286, 104/293
• US Class Current: 180/168
• CPC Class Codes: G05D 1/0263 using magnetic strips

Abstract

An improved magnetic object detecting system having high sensitivity and noise immunity is disclosed.

The detection system is of the type having a stimulation coil for generating a magnetic field and a pair of magnetic field detection coils, and the stimulation coil is of a magnetic core type employing a magnetic core.

Claims

1. A system for detecting an object including a magnetic material, said system comprising a first coil for generating a magnetic field that is directed towards said object, second and third coils arranged in a magnetic field path generated by said first coil at separate positions, said first coil including a magnetic core having first and second ends, said first and second ends being arranged near said second and third coils respectively, said magnetic core being formed substantially in a U shape, a first amplifier for amplifying an output of said second coil, a second amplifier for amplifying an output of said third coil, each of said first and second amplifiers having a gain control terminal for controlling a gain thereof, adding means for obtaining an addition signal proportional to the sum of outputs of said first and second amplifiers, and means for applying said addition signal to said gain control terminals of said first and second amplifiers thereby to control gains of said amplifiers, whereby said addition signal is kept at a predetermined value.

2. A system comprising a guide lane including a magnetic material, and a vehicle moving along said guide lane, said vehicle including a position detecting circuit including a first coil for generating a magnetic field towards said guide lane, second and third coils arranged between said first coil and said guide lane and control means responsive to outputs of said second and third coils for controlling direction of said vehicle so as to move along said guide lane, said first coil including a magnetic coil having a first end located near and second coil and a second end located near said third coil, said control means including gain control terminals on a first and a second amplifier connected for amplifying outputs of said second and third coils, respectively, to control gains of said amplifiers.

3. A system for detecting an object including a magnetic material, said system comprising a first coil for generating a magnetic field towards said object and second and third coils arrnaged in a magnetic field path generated by said first coil at separate positions, said first coil having a magnetic core including first and second ends, said first and second ends being arranged near said second and third coils respectively, a first amplifier for amplifying an output of said second coil, a second amplifier for amplifying an output of said third coil, each of said first and second amplifiers having a gain control terminal for controlling a gain thereof, adding means for obtaining an addition signal proportional to the sum of outputs of said first and second amplifiers, and means for applying said addition signal to said gain control terminals of said first and second terminals thereby to keep said addition signal at a predetermined value.

4. A system for detecting an object of magnetic material comprising a first coil for generating a magnetic field that is directed towards said object, and second and third coils arranged between said first coil and said object, said first coil including a first magnetic core having a first end located near said second coil and a second end located near said third coil, said second and third coils including second and third magnetic cores physically separated from said first magnetic core, a first amplifier for amplifying an output of said second coil, a second amplifier for amplifying an output of said third coil, each of said first and second amplifiers having a gain control terminal for controlling a gain thereof, adding means for obtaining an addition signal proportional to the sum of outputs of said first and second amplifiers, and means for applying said addition signal to said gain control terminals of said first and second amplifiers thereby to keep said addition signal at a predetermined value.