Water level measuring method and system

• US 6,586,760 B1
• Filed: 11/03/1999
• Issued: 07/01/2003
• Est. Priority Date: 11/03/1999
• Status: Expired due to Fees

• Current Assignee: The United States of America as represented by the Secretary of the Interior
• Original Assignee: The United States of America as represented by the Secretary of the Interior
• Inventors: Zalants, Michael George, Ross, Jerry Hubert, Hayes, Eugene Clark
• Primary Examiner(s): Le, Que T.
• Assistant Examiner(s): Luu, Thanh X.
• Application Number:
  US09/433,074
• Time in Patent Office: 1,336 Days
• Field of Search: 250/573-577, 250/201.1, 250/234-236, 356/249-255, 356/436, 356/440, 356/3.02, 333/77, 333/662.3, 732/93, 73/17.3, 340/612, 340/618, 340/619
• US Class Current: 250/577
• CPC Class Codes: G01F 23/292 Light , e.g. infrared or ultraviolet

Abstract

A method and system are provided for determining the level of a body of water, whether free flowing or stationary. Positionable mirrors are located at an area adjacent to but spaced from the body of water. The mirrors direct a laser beam at an angle to true vertical onto the surface of the body of water such that a portion of the beam is reflected from the surface. A receiver is located at a known distance from the mirrors on the opposite side of the body of water and in a common horizontal plane. The receiver receives a reflected laser beam and redirects the beam to a signal detector. A controller for the mirrors determines the angle to true vertical at which the mirrors are set after receiving an output from the signal detector. A simple calculation, based on the determined angle and the known distance between the mirrors and the receiver is then made of the distance from the common horizontal plane to the water surface so as to determine the water level.

Claims

1. A system for determining the level of a body of water, whether free flowing or stationary, said system comprising:

at least one positionable reflective element located at an area adjacent to but spaced from the body of water, for directing a laser beam at an angle to true vertical onto the surface of the body of water such that at least a portion of the directed beam is reflected from the surface to produce a reflected laser beam;

a motor including a motor shaft for controlling positioning of said at least one positionable reflective element;

a laser signal detector;

a receiver, located at a determined distance from the at least one positionable reflective element on the opposite side of the body of water from said at least one positionable reflective element and in a common horizontal plane with the at least one positionable reflective element, for receiving the reflected laser beam and redirecting the reflected laser beam to said signal detector so that said signal detector produces an output; and

a controller for controlling said motor to control positioning of said at least one positionable reflective element at an angle to true vertical, for receiving said output from said signal detector, for detecting motor shaft position and determining, based thereon, and on said output of said signal detector, a determined angle to the true vertical at which said at least one positionable reflective element is positioned when said reflected laser beam is received by said receiver, and for calculating, based on said determined angle and the determined distance between the at least one positionable reflective element and the receiver, the distance from the common horizontal plane to the water surface so as to determine the water level.

2. A system as claimed in claim 1 wherein said at least one positionable reflective element comprises first and second mirrors for reflecting said laser beam along two orthogonal axes.

3. A system as claimed in claim 2 wherein said first and second mirrors comprise verticle and horizontal positioning mirrors.

4. A system as claimed in claim 2 wherein said motor comprises first and second positioning motors controlled by said controller for controlling the positioning of said mirrors.

5. A system as claimed in claim 4 wherein said positioning motors comprise stepping or direct current (DC) voltage motors.

6. A system as claimed in claim 4 further comprising input means for inputting data to said controller.

7. A system as claimed in claim 6 wherein said input means comprises a keyboard.

8. A system as claimed in claim 4 further comprising a display unit for displaying the determined water level.

9. A system as claimed in claim 4 wherein said receiver comprises receiver optics for receiving the reflected beam and at least one corner prism for redirecting the beam to the signal detector.

10. A method for determining the level of a body of water, whether free flowing or stationary, said method comprising:

controlling a laser positionable by rotation of a motor shaft to direct a laser beam at a variable angle to true vertical from a positionable reflective element, located at an area adjacent to but spaced from the body of water, onto the surface of the body of water such that at least a portion of the beam is reflected from the surface;

receiving the portion of the beam reflected from the surface with a receiver located on the opposite side of the body of water from, and in substantially the same horizontal plane as, said reflective element, and redirecting the reflected beam portion so received to a signal detector for producing an output signaling reception of the redirected reflected beam;

determining the angle to true vertical at which the portion of the reflected beam is received by said receiver responsive to receiving said output from said signal detector based on the amount of motor shaft rotation which has occurred when said output signal is received; and

using (i) the angle to true vertical so determined and (ii) the distance between the reflective element and the receiver to calculate the distance from said horizontal plane to the water surface so as to determine the water level.

11. A method as claimed in claim 10 wherein said beam is dithered and a plurality of angle data points are taken in determining the angle to true vertical.

12. A method as claimed in claim 10 wherein said reflective element comprises horizontal and vertical positionable mirrors and said method further comprising controlling the positions of said mirrors in determining said angle to true vertical.

13. A method as claimed in claim 12 wherein the positions of the mirrors is initially set by a microcontroller at a predetermined angle with respect to true vertical and said angle is thereafter increased by the microcontroller until the reflected beam is received by the receiver.

14. A method as claimed in claim 13 wherein the signal detector signals the microcontroller when the reflected beam is received by said receiver and the microcontroller then determines the current angles of the mirrors.

15. A method as claimed in claim 14 wherein the signal detector is located in close proximity to said microcontroller and is electrically connected to said microcontroller.