System and method for sensing cable fault detection in a saw

Patent metadata

Field	Value
Publication number	US-10758989-B2
Application number	US-201615060709-A
Country	US
Kind code	B2
Filing date	Mar 4, 2016
Priority date	Mar 12, 2015
Publication date	Sep 1, 2020
Grant date	Sep 1, 2020

Abstract

A method for detection of a fault in a sensing cable within a saw detects potential failures in a sensing cable that is part of an object detection system in the saw. The method includes generating a predetermined excitation signal transmitted through a first conductor and a second conductor in the sensing cable, detecting a return signal from the first conductor and the second conductor in the sensing cable in response to the predetermined excitation signal, identifying a signal-to-noise ratio (SNR) of the return signal, and generating an output indicating a fault in the sensing cable in response to the SNR of the return signal being below a predetermined value.

First claim

What is claimed:

1. A method for detection of a fault in a sensing cable within a saw comprising:
generating, with a signal generator, a predetermined excitation signal transmitted through a first conductor and a second conductor in the sensing cable, the first conductor being electrically connected to a plate in the saw and the second conductor being electrically connected to an implement in the saw positioned at a predetermined distance from the plate;
detecting, with a controller, a return signal corresponding to the excitation signal through the first conductor and the second conductor in the sensing cable;
identifying, with the controller, a signal-to-noise ratio (SNR) of the return signal; and
generating, with the controller and a user interface device in the saw, an output indicating a fault in the sensing cable in response to the SNR of the return signal being below a predetermined value.

2. The method of claim 1 further comprising:
deactivating, with the controller, a motor in the saw prior to generating the predetermined excitation signal to enable identification of the fault in the cable while the motor remains deactivated.

3. The method of claim 1 , the generating of the predetermined excitation signal further comprising:
generating, with a clock source in the saw, a sinusoidal signal at a predetermined frequency.

4. The method of claim 3 further comprising:
generating, with an amplifier, an amplified sinusoidal signal based on the sinusoidal signal from the clock source; and
transmitting the amplified sinusoidal signal through the sensing cable.

5. The method of claim 1 , the generating of the predetermined excitation signal further comprising:
generating, with a clock source in the saw, a series of delta pulses at a predetermined frequency.

6. The method of claim 1 further comprising:
disabling, with the controller, operation of a motor in the saw in response to the SNR being below the predetermined threshold.

7. The method of claim 1 further comprising:
transmitting, with a first winding in a transformer in the saw, the predetermined excitation signal from the signal generator to the first conductor and the second conductor in the sensing cable.

8. The method of claim 1 further comprising:
receiving, with the controller, the return signal through a third conductor in the sensing cable, the third conductor being electrically connected to the plate and to an analog to digital convertor associated with the controller.

9. A system for detecting faults in a sensing cable in a saw comprising:
a sensing cable including a first conductor and a second conductor;
a plate, the plate being electrically connected to the first conductor in the sensing cable;
an implement, the implement being positioned at a predetermined distance from the plate and the implement being electrically connected to the second conductor in the sensing cable;
a signal generator configured to generate a predetermined excitation signal transmitted through the first conductor and the second conductor of the sensing cable;
a user interface device; and
a controller connected to the signal generator, the user interface device, and the first conductor and the second conductor of the sensing cable, the controller being configured to:
operate the signal generator to generate the predetermined excitation signal;
detect a return signal corresponding to the excitation signal through the first conductor and the second conductor in the sensing cable;
identify a signal-to-noise ratio (SNR) of the return signal; and
generate an output with the user interface device indicating a fault in the sensing cable in response to the SNR of the return signal being below a predetermined value.

10. The system of claim 9 further comprising:
a motor configured to move the implement during operation of the motor; and
the controller being operatively connected to the motor and configured to:
deactivate the motor prior to the operation of the signal generator to generate the predetermined excitation signal to enable identification of the fault in the cable and the motor remains deactivated.

11. The system of claim 9 , the signal generator further comprising:
a clock source configured to generate a sinusoidal signal at a predetermined frequency as the excitation signal.

12. The system of claim 9 , the signal generator further comprising:
an amplifier configured to generate an amplified sinusoidal signal based on the sinusoidal signal from the clock source.

13. The system of claim 9 , the signal generator further comprising:
a clock source configured to generate a series of delta pulses at a predetermined frequency.

14. The system of claim 9 further comprising:
a motor configured to move the implement during operation of the motor; and
the controller being operatively connected to the motor and further configured to:
disable the operation of the motor in response to the SNR being below the predetermined threshold.

15. The system of claim 9 further comprising:
a transformer with a first winding connected to the first conductor in the sensing cable and the second conductor in the sensing cable; and
the signal generator being configured to transmit the predetermined excitation signal to the first conductor and the second conductor through the first winding.

16. The system of claim 9 further comprising:
a third conductor in the sensing cable, the third conductor being electrically connected to the plate and to an analog to digital convertor associated with the controller; and
the controller being further configured to:
receive the return signal through the third conductor in the sensing cable.

Assignees

• Bosch Tool Corp
• Bosch Gmbh Robert

Inventors

• Volpert Dieter
• Ramaswamy Bharadwaja Maharshi
• Chandrashekar Indumathi
• Mishra Ankur
• Ayyamperumal Seenivasan
• Laliberte Eric

Classifications

• B27G19/008

  with sensing of human contact or proximity with the blade · CPC title

• G01R31/58

  Testing of lines, cables or conductors (testing of electric windings G01R31/72) · CPC title

• G01R31/52

  Testing for short-circuits, leakage current or ground faults · CPC title

• G01R31/54

  Testing for continuity · CPC title

• F16P3/12

  with means, e.g. feelers, which in case of the presence of a body part of a person in or near the danger zone influence the control or operation of the machine (F16P3/08 takes precedence) · CPC title