Back-up proximity sensor for a vehicle employing dual sonic transducers

• US 6,173,233 B1
• Filed: 12/11/1998
• Issued: 01/09/2001
• Est. Priority Date: 12/11/1998
• Status: Expired due to Fees

• Current Assignee: Eaton Corp. (Wisconsin) (Eaton Corporation PLC.)
• Original Assignee: Eaton Corp. (Wisconsin) (Eaton Corporation PLC.)
• Inventors: Bernhard, Richard G., Pahl, Birger, Janutka, William J.
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): Donnelly, Arthur D.
• Application Number:
  US09/210,174
• Time in Patent Office: 760 Days
• Field of Search: 701/300, 701/47, 701/301, 340/435, 340/903, 340/901, 340/904, 340/436
• US Class Current: 701/301
• CPC Class Codes: G01S 15/18 wherein range gates are used
• CPC Class Codes: G01S 15/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S15/46
• CPC Class Codes: G01S 15/931 of land vehicles
• CPC Class Codes: G01S 7/523 Details of pulse systems short-range imaging G01S7/52017; methods or devices for transmitting, conducting or directing sound G10K11/18

Abstract

A sonic back-up proximity sensor employs a first sonic transducer and a second sonic transducer mounted on a rearward portion of a riding lawn mower to create three discrete zones of protection. The first sonic transducer has an associated first region of coverage, or sector, and the second sonic transducer has an associated second sector. The first sonic transducer and second sonic transducer are directed toward one another such that the first sector and second sector at least partially overlap. The overlapping portion of the first sector and second sector provides redundant coverage in an area directly behind the lawn mower. The non-overlapping portion of the first sector defines a second protection zone on one side of the lawn mower. The non-overlapping portion of the second sector defines a third protection zone on a second side of the lawn mower. By selectively transmitting, receiving and sequentially storing reflected sonic energy, a sonic back-up proximity sensor formed in accordance with the present invention determines the distance and position of an object located behind the riding lawn mower.

Claims

1. A sonic back-up proximity sensor for a vehicle, the sonic sensor comprising:

a first sonic transducer, the first sonic transducer transmitting and receiving sonic energy in a first sector;

a second sonic transducer, the second sonic transducer transmitting and receiving sonic energy in a second sector; and

the first sonic transducer and second sonic transducer being substantially horizontally separated and angularly directed such that the first sector and second sector partially overlap, thereby creating a first protection zone, a second protection zone and a third protection zone.

2. A sonic back-up proximity sensor as defined by claim 1, wherein the first sonic transducer transmits sonic energy during a first time period, the first sonic transducer and the second sonic transducer receive reflected sonic energy during a second time period, the second sonic transducer transmits sonic energy during a third time period, the first sonic transducer and the second sonic transducer receive reflected sonic energy during a fourth time period, and the first sonic transducer and the second sonic transducer monitor the first protection zone, the second protection zone, and the third protection zone substantially simultaneously during the second time period and the fourth time period.

3. A sonic back-up proximity sensor as defined by claim 2, wherein the first sector and second sector cover a region of approximately 90 degrees.

4. A sonic back-up proximity sensor as defined by claim 3, wherein the first sonic transducer and second sonic transducer are each angularly directed by 45 degrees toward each other.

5. A sonic back-up proximity sensor as defined by claim 4, wherein the first, the second and the third protection zones protect a combined area of approximately 180 degrees behind the vehicle.

6. A sonic back-up proximity sensor for a vehicle, the sonic sensor comprising:

a transducer interface circuit generating and selectively routing a sonic signal;

a first sonic transducer, the first sonic transducer transmitting the sonic signal generated by the transducer interface circuit into a first sector, the first sonic transducer receiving at least a portion of the sonic signal reflected from a target in the first sector;

a second sonic transducer, the second sonic transducer transmitting the sonic signal generated by the transducer interface circuit into a second sector and receiving at least a portion of the sonic energy reflected from a target in the second sector, the first sonic transducer and second sonic transducer being substantially horizontally separated and angularly directed such that the first sector and second sector at least partially overlap, thereby creating a first protection zone, a second protection zone and a third protection zone; and

a detector circuit, the detector circuit generating a first detector output signal in response to sonic energy received by the first sonic transducer and generating a second detector output signal in response to sonic energy received by the second sonic transducer.

7. A sonic back-up proximity sensor as defined by claim 6, wherein the first sonic transducer transmits the sonic signal during a first time period, the first sonic transducer and the second sonic transducer receive at least a portion of the sonic signal reflected from a target during a second time period, the second sonic transducer transmits the sonic signal during a third time period, the first sonic transducer and the second sonic transducer receive at least a portion of the sonic signal reflected from a target during a fourth time period, and the first sonic transducer and the second sonic transducer monitor the first protection zone, the second protection zone, and the third protection zone substantially simultaneously during the second time period and the fourth time period.

8. A sonic back-up proximity sensor for a vehicle as defined by claim 7, wherein the transducer interface circuit comprises:

a tone burst generator, the tone burst generator generating the sonic signal provided to the first sonic transducer and the second sonic transducer; and

an alternating logic circuit, the alternating logic circuit receiving the sonic signal from the tone burst generator and alternately directing the sonic signal to the first sonic transducer and the second sonic transducer.

9. A sonic back-up proximity sensor for a vehicle as defined by claim 7, wherein the detector circuit comprises:

a first amplifier circuit operatively coupled to the first sonic transducer and receiving a signal therefrom corresponding to reflected sonic energy received by the first sonic transducer;

a first rectifier circuit operatively coupled to the first amplifier circuit;

a first low pass filter operatively coupled to the first rectifier circuit;

a first level shifting circuit operatively coupled to the first low pass filter, the first level shifting circuit providing the first detector output signal;

a second amplifier circuit operatively coupled to the second sonic transducer and receiving a signal therefrom corresponding to reflected sonic energy received by the second sonic transducer;

a second rectifier circuit operatively coupled to the second amplifier circuit;

a second low pass filter operatively coupled to the second rectifier circuit; and

a second level shifting circuit operatively coupled to the second low pass filter, the second level shifting circuit providing the second detector output signal.

10. A sonic back-up proximity sensor for a vehicle as defined by claim 9, wherein the first amplifier circuit and second amplifier circuit are variable gain amplifiers and the detector circuit further comprises:

a gain control circuit, the gain control circuit providing a signal to the first amplifier circuit and second amplifier circuit changing the gain of the amplifier circuits during the second and fourth time periods.

11. A sonic back-up proximity sensor for a vehicle as defined by claim 10, wherein the gain control circuit effects a logarithmically increasing amplifier gain with increasing time during the second and fourth time periods.

12. A sonic back-up proximity sensor for a vehicle as defined by claim 6, further comprising:

a signal processing circuit, the signal processing circuit determining target presence in response to the first output signal and the second output signal.

13. A sonic back-up proximity sensor for a vehicle as defined by claim 12, wherein the signal processing circuit comprises:

a microprocessor;

an analog to digital converter, the analog to digital converter being responsive to the first output signal and the second output signal and providing digital signals to the microprocessor representing the first output signal and second output signal;

a memory circuit, the memory circuit being operatively coupled to the microprocessor and storing the digital signals from the analog to digital converter; and

an output circuit, the output circuit being responsive to the microprocessor and providing an indication to an operator of the vehicle that a target is present.

14. A sonic back-up proximity sensor for a vehicle as defined by claim 13, wherein the indication is at least one of a visual signal, an audible signal and a tactile signal.

15. A sonic back-up proximity sensor for a vehicle as defined by claim 14, further comprising a vehicle systems processor, the vehicle systems processor being operatively coupled to the microprocessor and providing a control signal altering the operation of the vehicle when a target is detected.

16. A sonic back-up proximity sensor for a vehicle as defined by claim 15, wherein the vehicle includes a lawn cutting attachment responsive to the control signal, the control signal disabling the lawn cutting attachment when a target is detected.

17. A sonic back-up proximity sensor for a vehicle as defined by claim 15, wherein the vehicle includes an engine responsive to the control signal, the control signal disabling the engine when a target is detected.

18. A sonic back-up proximity sensor for a vehicle as defined by claim 15, wherein the vehicle includes a braking system responsive to the control signal, the control signal engaging the braking system when a target is detected.

19. A sonic back-up proximity sensor for a vehicle as defined by claim 13, which further comprises:

a difference filter, the difference filter being responsive to current digital signals corresponding to current first and second output signals and previous digital signals corresponding to previously occurring first and second output signals and generating an output signal corresponding to the differences between the current digital signals and the previous digital signals which correspond in distance.

20. A sonic back-up proximity sensor for a vehicle as defined by claim 13, which further comprises:

a memory cell filter, the memory cell filter being responsive to at least current digital signals corresponding to current first and second output signals and previous digital signals corresponding to previously occurring first and second output signals and generating an output signal corresponding to the averages of the current digital signals and the previous digital signals which correspond in distance.

21. A sonic back-up proximity sensor for a vehicle as defined by claim 13, which further comprises:

a sliding filter, the sliding filter being responsive to at least current digital signals corresponding to current first and second output signals and previous digital signals corresponding to previously occurring first and second output signals and generating an output signal corresponding to the averages of the current digital signals and the previous digital signals which correspond in time.

22. A method of detecting a target behind a vehicle comprising the steps:

transmitting sonic energy into a first sector during a first time period;

monitoring reflected sonic energy from a target situated within at least one of the first sector and the second sector substantially simultaneously from the first sector and the second sector during a second time period;

receiving reflected sonic energy from a target situated within at least one of the first sector and the second sector during a second time period, the first and second sectors being at least partially overlapping;

transmitting sonic energy into the second sector during a third time period;

monitoring reflected sonic energy from the target situated within at least one of the first sector and the second sector substantially simultaneously from the first sector and the second sector during a fourth time period;

receiving reflected sonic energy from the target situated within at least one of the first sector and the second sector during the fourth time period; and

determining target position based on the sonic energy received in the second and fourth time periods.

23. A method of detecting a target as defined by claim 22, wherein the determining step includes the steps of:

determining whether a target is in the first sector, the second sector or both the first and second sectors;

determining a time interval between transmitting and receiving the sonic energy; and

determining target distance based on the time interval.