Electricity: measuring and testing – Magnetic – Displacement
Reexamination Certificate
1998-12-21
2001-04-17
Oda, Christine (Department: 2862)
Electricity: measuring and testing
Magnetic
Displacement
C324S207110, C324S207220
Reexamination Certificate
active
06218828
ABSTRACT:
TECHNICAL FIELD
The present invention relates to sensing the position of a first element relative to a second element and, more particular, to a novel method and apparatus for sensing the articulation angle between a first and second element.
BACKGROUND ART
In articulated machines, such as, but not limited to, articulated wheel loaders or motor graders, it is important to be able to determine the articulation angle of the machine. This information enables the function of various electronic control systems during the operation of the machine. These systems include, but are not limited to, “steer-by-wire”, automatic yaw control, and torque control systems. However, there are several obstacles in trying to determine the articulation angle using present devices. In one embodiment, a potentiometer is used to measure an articulation angle. However, temperature, age and the limited number of cycles due to contact technology, confines its use to less demanding applications. Drift of such devices requires a periodic calibration routine to be executed to ensure satisfactory operation. These calibration routines are time consuming, highly inconvenient, and have to be performed as a separate operation of the machine.
The present invention is directed to overcoming one or more of the problems identified above.
DISCLOSURE OF THE INVENTION
In one aspect of the invention, an apparatus for determining the position of a first and a second element relative to each other is disclosed. The apparatus includes a magnet being attached to the first element, a first and second sensing device being adapted to detect a magnetic flux density of the magnet and a controller adapted to determine a position of said first element relative to said second element.
In another aspect of the invention, a method for determining a position of a first element having a magnet and a second element having a plurality of sensing devices, relative to each other. The method includes the steps of sensing the magnetic flux density of the magnet and determining a position of said first element relative to said second element in response to the first and second sensed flux densities.
These and other aspects and advantages of the present invention will become apparent upon reading the specification in connection with the drawings and claims.
REFERENCES:
patent: 4330748 (1982-05-01), Hoden
patent: 4857842 (1989-08-01), Sturman et al.
patent: 4990850 (1991-02-01), Votruba
patent: 5041785 (1991-08-01), Bogaerts et al.
patent: 5336996 (1994-08-01), Rusnak
patent: 5670877 (1997-09-01), Scheiber
patent: 5682095 (1997-10-01), Mathes et al.
patent: 5793201 (1998-08-01), Nelle et al.
Patent Application Docket No. 97-650, entitled “Sensor for Computing the Angular Velocity of a Rotational Body,” Filed Nov. 17, 1998.
Bates Kent C.
Strashny Igor
Caterpillar Inc.
McPherson III W. Bryan
Oda Christine
Zaveri S.
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