Electricity: measuring and testing – Magnetic – Displacement
Reexamination Certificate
1998-11-27
2001-06-12
Snow, Walter E. (Department: 2862)
Electricity: measuring and testing
Magnetic
Displacement
C324S207170, C318S653000
Reexamination Certificate
active
06246228
ABSTRACT:
ORIGIN OF INVENTION
This invention was made by employees of the United States Government and may be manufactured and used by or for the Government for Governmental purposes without the payment of royalties.
BACKGROUND OF INVENTION
1. Field of Invention
The present invention is directed to a non-contact position sensor and more particularly to a non-contact position sensor for an actuator or for other settings in which an air gap is required to fluctuate.
2. Description of Related Art
It is often desirable to have a non-contact position sensor when closing a servo loop around an actuator. This becomes difficult in many applications where weight and volume are critical because many non-contact position sensors are implemented using optical devices. If an optical device is not used, then a Hall device is usually chosen.
For similar applications, optical devices are usually large and cumbersome to work with and are often impossible to mount without having the sensor become the device which dictates the volume. Optical sensors need a light source, which also requires volume and extra alignment problems.
Hall sensors have the disadvantage of nonlinearity and must be precision mounted to obtain accurate measurement of position. The Hall sensors also need another component, usually a permanent magnet, for use in sensing position. Another disadvantage of Hall devices is their reaction to permanent and fluctuating magnetic fields.
A final disadvantage of Hall devices and the like is that such devices require a fixed air gap in the motor. In some applications, however, it is required that the air gap fluctuate. For example, one type of actuator for which such devices cannot be used is a linear permanent magnet motor, in which the winding is fixed and the permanent magnet is allowed to move.
SUMMARY OF THE INVENTION
It is an object of the invention to develop a non-contact position sensor which requires a minimum of weight and volume.
It is another object of the invention to develop a non-contact position sensor which can be easily implemented with a given actuator, such as a linear permanent magnet motor where the winding is fixed and the permanent magnet is allowed to move.
It is a further object of the invention to develop a non-contact position sensor which uses existing actuator windings.
It is a still further object of the invention to use electronics to develop a very accurate, low volume, low weight non-contact position sensor.
To achieve these and other objects, the present invention is directed to a position sensor for sensing a position of an armature in an actuator, the armature having at least one armature winding, the position sensor comprising: excitation wave generating means for generating an excitation wave; at least one excitation winding for generating an excitation magnetic field from the excitation wave and for applying the excitation magnetic field to at least one armature winding to cause at least one armature winding to generate a response signal; detecting means, connected to at least one armature winding, for detecting the response signal in the armature winding; and demodulating means for determining the position of the armature from the response signal detected by the detecting means.
The present invention is further directed to a position controller for sensing and controlling a position of an armature in an actuator, the armature having at least one armature winding, the position controller comprising a position sensor such as that described above and position controlling means, receiving the detected position signal, for generating a position control signal and outputting the position control signal to the at least one armature winding.
Linear position can be detected in either a single axis or dual axes simultaneously. The design is simplified because the sensor and actuator are co-located (have the same coordinate frame). Only a single component (the excitation windings) needs to be added to existing actuators.
The present invention can be used for vibration isolation for glovebox applications. It can be used for vibration isolation systems using electromagnetic actuators for integrated circuit manufacturing equipment and other sensitive manufacturing machines. It can also be used as a linear position sensor for motors, copiers, antilock brake systems, and the like, and in robotics.
REFERENCES:
patent: 2980837 (1961-04-01), Wu
patent: 4251762 (1981-02-01), Williams
Alhorn Dean C.
Howard David E.
McGroary James J.
Snow Walter E.
The United States of America as represented by the Administrator
LandOfFree
Non-contact linear actuator position sensor having a... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Non-contact linear actuator position sensor having a..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Non-contact linear actuator position sensor having a... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2543576