Method and apparatus for measuring the length of a multi-section telescopic boom

• US 5,877,693 A
• Filed: 05/27/1998
• Issued: 03/02/1999
• Est. Priority Date: 05/27/1998
• Status: Expired due to Term

• Current Assignee: Grove US L L C
• Original Assignee: Grove US L L C
• Inventors: Eyler, Francis R.
• Primary Examiner(s): Hofsass, Jeffrey A.
• Assistant Examiner(s): TRIEU, VAN THANH
• Application Number:
  US09/084,419
• Time in Patent Office: 279 Days
• Field of Search: 340/685, 340/686.1, 340/539, 340/673, 212/276, 212/278, 212/280, 324/532, 324/533, 324/535
• US Class Current: 340/685
• CPC Class Codes: B66C 23/905 electrical
• CPC Class Codes: G01S 11/16 using difference in transit time between electrical and acoustic signals
• CPC Class Codes: H01Q 1/12 Supports; Mounting means

Abstract

The boom length measurement includes a transmitting unit mounted on the fly section of a multi-section telescopic boom, and a receiving unit mounted on the base section of the multi-section telescopic boom. The transmitting unit transmits a first and second signal having first and second transmission speeds, respectively. The second transmission speed is less than the first transmission speed. Based on a difference in transit times of the first and second signals received by the receiving unit, a length determiner determines the length of the multi-section telescopic boom. A display displays the determined length.

Claims

1. A boom length measurement apparatus, comprising:

a transmitting unit, mounted on an extendable section of a multi-section telescopic boom, transmitting a first signal having a first transmission speed and a second signal having a second transmission speed, said second transmission speed being less than said first transmission speed;

a receiving unit, mounted to a fixed support, receiving said first and second signals; and

a length determiner determining a length of time between receipt of said first and second signals by said receiving unit, and determining a length of said multi-section telescopic boom based on said length of time.

2. The apparatus of claim 1, wherein said extendable section of said multi-section telescopic boom is a fly section.

3. The apparatus of claim 1, wherein said transmitting unit includes a first transmitter transmitting said first signal, and a second transmitter transmitting said second signal.

4. The apparatus of claim 1 wherein said first signal is a radio frequency signal, and said second signal is an ultrasonic frequency signal.

5. The apparatus of claim 1, wherein said receiving unit includes a first receiver receiving said first signal and a second receiver receiving said second signal.

6. The apparatus of claim 1, wherein said length determiner includes a counter, said counter resetting a count value upon receipt of said first signal, and increasing said count value at a predetermined rate until receipt of said second signal, said count value indicating said length of said multi-section telescopic boom.

7. The apparatus of claim 6, wherein said predetermined rate is set such that said count value is said length of said multi-section telescopic boom.

8. The apparatus of claim 1, further comprising:

a power source;

a switch selectively supplying power output by said power source to said transmitter in response to a power control signal; and

a boom control enable transmitter receiving a boom control signal indicating that a user is one of extending and retracting said multi-section telescopic boom and transmitting said power control signal to said switch upon receipt of said boom control signal.

9. The apparatus of claim 1, further comprising:

a fail safe circuit receiving a boom control signal indicating that a user is one of extending and retracting said multi-section telescopic boom, determining if said length of said multi-section telescopic boom output by said length determiner changes upon receipt of said boom control signal, and outputting a warning to said user if said length output by said length determiner does not change.

10. The apparatus of claim 1, further comprising:

a display displaying said length output by said length determiner.

11. The apparatus of claim 1, wherein said receiving unit is mount to a base section of said multi-section telescopic boom.

12. The method of claim 1, further comprising:

selectively supplying power output by a power source to said transmitter using a switch in response to a power control signal; and

receiving a boom control signal indicating that a user is one of extending and retracting said multi-section telescopic boom; and

transmitting said power control signal to said switch upon receipt of said boom control signal.

13. The method of claim 1, further comprising:

receiving a boom control signal indicating that a user is one of extending and retracting said multi-section telescopic boom;

second determining if said length of said multi-section telescopic boom output by said first determining step changes upon receipt of said boom control signal; and

outputting a warning to said user if said length output by said second determining step does not change.

14. The method of claim 1, further comprising:

displaying said length output by said first determining step.

15. A method of measuring a boom length, comprising:

transmitting a first signal having a first transmission speed using a transmitting unit mounted to an extendable section of a multi-section telescopic boom;

transmitting a second signal having a second transmission speed using said transmitting unit, said second transmission speed being less than said first transmission speed;

receiving said first and second signals using a receiving unit mounted to a fixed support; and

first determining a length of said multi-section telescopic boom based on a length of time between receipt of said first and second signals by said receiving unit.

16. The method of claim 15, wherein said extendable section of said multi-section telescopic boom is a fly section.

17. The method of claim 15, wherein said first signal is a radio frequency signal, and said second signal is an ultrasonic frequency signal.

18. The method of claim 15, wherein said determining step comprises:

resetting a count value upon receipt of said first signal;

increasing said count value at a predetermined rate until receipt of said second signal, said count value indicating said length of said multi-section telescopic boom.

19. The method of claim 18, wherein said predetermined rate is set such that said count value is said length of said multi-section telescopic boom.