1. A method of predicting failure in of geotechnical structures, comprising:
measuring specific AE signals generated from damages to an outer waveguide by the deformation or movement in geotechnical structures using a measurement apparatus affixed with AE sensors, wherein the measurement apparatus affixed with AE sensors, at least one of which is attached to the inner waveguide, is fixedly installed in a borehole and passes through an expected failure plane and includes both an inner waveguide, which is formed of metallic material that is intended to prevent sharp attenuations of AE signals, and an outer waveguide, which firmly encloses at least one AE sensor as well as the inner waveguide and is formed of a homogeneous brittle material that is intended to generate specific AE signals regardless of ground conditions or formations when the outer waveguide is damaged by the events that indicated there are deformations or movements in the geotechnical structures;
obtaining parametric values in the geotechnical structures, which indicate damage levels in the geotechnical structures, in order to predict the failure in the geotechnical structures, wherein these parametric values are extracted from the AE signals measured by at least one AE;
performing at least one of laboratory tensile, shear and compression tests with respect to a laboratory testing measurement apparatus affixed with AE sensors that is the same as the installed measurement apparatus in the geotechnical structures, and obtaining AE signals generated by the damage of an outer waveguide of the laboratory testing measurement apparatus affixed with AE sensors obtaining laboratory parametric values with applied load in the laboratory tests, which correspond to the parametric values in the geotechnical structures, are extracted from AE signals generated by the damage of the outer waveguide of the laboratory testing measurement apparatus; and
comparing one or more reference parametric values and obtained parametric values in geotechnical structures, wherein the one or more reference parametric values indicate the damage levels in geotechnical structures, are included in laboratory parametric values corresponding to the parametric values in the geotechnical structures, and the obtained parametric values in geotechnical sturctures are obtained in the parametric values-obtaining step in geotechnical structures, and evaluating where the geotechnical structures correspond to the damage levels from one or more reference parametric values.
2. The method of claim 1, wherein the obtained parametric values the geotechnical structures are at least one of a count value, an accumulated count value and a count frequency value of the measured AE signals,
wherein the count is a parameter which is indicated by the number of times, of which amplitudes exceed a threshold in an AE signal waveform obtained from the AE signal during a desired time interval \u0394t1, which are generated from the damages to the outer waveguide by specific events,
the accumulated count is a parameter, which is an accumulative sum of the count values with respect to the different specific events according to the lapse of time, and
the count frequency is a parameter which is a total of the count values obtained during a desired time interval At2 with respect to the different specific events according to the lapse of time, and
assuming that k is a natural number equal to or larger than 2, \u0394tt is \u0394t2=k\u0394t1.
3. The method of claim 1, wherein the obtained parametric values in the geotechnical structures are at least one of an energy value, an accumulated energy value and a energy frequency value of the measured AE signal,
wherein the energy is a parameter which is indicated by a surface area of an envelope of a AE signal waveform or a maximum amplitude in the AE signal waveform. The AE signal waveform is obtained from the AE signal during a desired time interval \u0394t1, which are generated from the damages to the outer waveguide by specific events, and
the accumulated energy is a parameter which is an accumulative sum of the energy values with respect to the different specific events according to the lapse of time, and
the energy frequency is a parameter which is a total of the energy values obtained during a desired time interval \u0394t2 with respect to the different specific events according to the lapse of time, and
assuming that k is a natural number equal to or larger than 2, \u0394t2 is \u0394t2=k\u0394t1.
4. The method of any one of claims 1 to 3, wherein coefficients of reference parameters corresponding to the damage levels in the geotechnical structures are C1, C2 and C3, and
the reference coefficient C1 is a value for evaluating where the damage level in the geotechnical structure corresponds to a \u2018dangerous level\u2019 in which the damage in the geotechnical structures may be developed to a macro-failure in the geotechnical structures and also a value when load corresponding to 80% of failure strength is applied to the laboratory testing measurement apparatus affixed with AE sensors used in the laboratory tests, and
the reference coefficient C2 is a value for evaluating where the damage level in the geotechnical structures corresponds to a \u2018damage developing level\u2019 in which the damage in the geotechnical structures sharply grows and thus can proceed to the \u2018dangerous level\u2019, and also a value when load corresponding to 60% of failure strength is applied to the laboratory measurement apparatus affixed with AE sensors used in the laboratory tests, and
the reference coefficient O3 is a value for evaluating whether the damage level in the geotechnical structures passes a \u2018safe level\u2019 in which the geotechnical structures are insignificantly damaged or not damaged, and then their damage level arrives at a \u2018damage proceeding level\u2019 in which the geotechnical structures are slowly damaged and thus can proceed to the \u2018damage developing level\u2019, and also a value when load corresponding to 40% of failure strength is applied to the laboratory measurement apparatus affixed with AE sensors used in the laboratory tests.
5. A method of predicting failure in geotechnical structures, comprising:
measuring specific AE signals generated from damages to an outer waveguide by a deformation or movement in the geotechnical structures using a measurement apparatus affixed with AE sensors, wherein the measurement apparatus affixed with AE sensors is fixedly installed in a borehole and passes through an expected failure plane and includes both an inner waveguide, which is formed of metallic material that is intended to prevent sharp attenuations of AE signals, and an outer waveguide; two AE sensors are attached to the inner waveguide so that the expected failure plane is interposed between two AE sensors, and one of which above the other; the outer waveguide firmly encloses at least one AE sensor as well as the inner waveguide; and the outer waveguide is formed of a homogeneous brittle material that is intended to generate specific AE signals regardless of ground conditions or formations when the outer waveguide is damaged by the events that indicated there are deformations or movements in the geotechnical structures;
obtaining arrival times from an AE signal generated from the damages to the outer waveguide by a specific event, wherein the AE signal is measured by the upper AE sensor and the lower AE sensor and the arrival time is defined as time when an initial AE signal waveform arrives at each of the upper and lower AE sensors;
determining a distance between the upper AE sensor and a source of the AE signal or a distance between the lower AE sensor and the source of the AE signal from a difference between the arrival times obtained from the AE signal measured by the upper AE sensor and the lower AE sensor;
obtaining at least one parametric values of a summed magnitude value, an accumulated summed magnitude value and am summed magnitude frequency value of the AE signals measured by the upper or lower AE sensor, in order to predict the failure in the geotechnical structures from the AE signals measured by the upper or lower AE sensor;
performing at least one of laboratory tensile, shear and compression tests with respect to a laboratory testing measurement apparatus affixed with AE sensors that is the same as the installed measurement apparatus in the geotechnical structures, and obtaining AE signals generated by the damage of an outer waveguide of the laboratory testing measurement apparatus affixed with AE sensors, wherein obtaining laboratory parametric values with applied load in the laboratory tests, which correspond to the parametric values in the geotechnical structures, are extracted from AE signals generated by the damage of the outer waveguide of the laboratory testing measurement apparatus; and
comparing one or more reference parametric values and obtained parametric values in geotechnical structures, wherein the one or more reference parametric values indicate the damage levels in geotechnical structures, are among laboratory parametric values corresponding to the parametric values in the geotechnical structures and the obtained parametric values in geotechnical sturctures are obtained in the parametric values-obtaining step in geotechnical structures, and
wherein the summed magnitude is a parameter which is indicated by G(d)\u0398F(E) of the AE signals and the AE signals are measured during a desired time interval \u0394t1, and generated from the damage to an outer waveguide by the specific events,
and the accumulated summed magnitude is a parameter, which is an accumulative sum of the summed magnitude values with respect to the different specific events according to the lapse of time, and
the summed magnitude frequency is a parameter which is a total of the summed magnitude values obtained during a desired time interval \u0394t2 with respect to the different specific events according to the lapse of time, and
assuming that k is a natural number equal to or larger than 2, \u0394t2 is \u0394t2=k\u0394t1, and
d is a distance between one of the upper and lower AE sensors and the source of the AE signal, which is used in obtaining the summed magnitude value in the determining of distance from specific source and
G(d) is an attenuating function according to d, and is indicated by G(d)=A1d+A2 or G(d)=B1e\u2212d+B2, and
A1, A2, B1 and B2 are regression coefficients which are decided by a material of the inner guide, and
\u0398 is an operator decided by G(d), and
F(E) is an energy function of the AE signal used in obtaining of the summed magnitude value.
6. The method of claim 5, wherein F(E) is one of
log
\ue8a0
(
ppA
2
\ue89e
\u03c0
\ue89e
\ue89e
f
)
,
log
(
\u2211
j
=
1
n
\ue89e
A
j
2
n
\ue89e
)
and dBpeak,
wherein ppA is a maximum particle acceleration of the AE signal used in obtaining the summed magnitude value,
f is a dominant frequency of the AE signal used in obtaining the summed magnitude value,
n is a count of the AE signal used in obtaining the summed magnitude value,
Aj is an amplitude of a j-th waveform forming the AE signal used in obtaining the summed magnitude value, which is over a threshold value, and
dBpeak is a maximum amplitude in the waveform forming the AE signal used in obtaining the summed magnitude value.
7. The method of claim 5 or 6, wherein coefficients of reference parameters corresponding to the damage levels in the geotechnical structures are C1, C2 and C3, and,
the reference coefficient C1 is a value for evaluating where the damage level in the geotechnical structures corresponds to a \u2018dangerous level\u2019 in which a macro-failure in the geotechnical structures may be occurred, and also a value when force corresponding to 80% of failure strength is exerted to the laboratory testing measurement apparatus affixed with AE sensors used in the laboratory test,
the reference coefficient C2 is a value for evaluating where the damage level in the geotechnical structures corresponds to a \u2018damage developing level\u2019 in which the geotechnical structures are sharply damaged and thus can proceed to the \u2018dangerous level\u2019, and also a value when force corresponding to 60% of failure strength is exerted to the laboratory measurement apparatus affixed with AE sensors used in the laboratory test, and
the reference coefficient C3 is a value for evaluating whether the damage level in the geotechnical structures passes a \u2018safe level\u2019 in which the geotechnical structures are insignificantly damaged or not damaged, and then arrive at a \u2018damage proceeding level\u2019 in which the geotechnical structures are slowly damaged and thus can proceed to the \u2018damage developing level\u2019, and also a value when force corresponding to 40% of failure strength is exerted to the laboratory measurement apparatus affixed with AE sensors used in the laboratory test.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A drive control system for a multi-phase and sensor-less motor for driving the motor by switching a current of a field coil in each phase of the motor depending on a rotational phase of the motor, comprising:
a power feeding circuit feeding electrical power, for a predetermined period, to a selected field coil when the selected field coil is in a phase other than a detection phase to induce a voltage in another field coil;
an induced voltage detecting circuit detecting the induced voltage on said another field coil during the detection phase;
a magnetic pole position detecting circuit detecting a magnetic pole position of a rotor based on an amplitude of said induced voltage;
a driving circuit determining a power supply phase for drive of the motor based on the magnetic pole position, and executing power supply for drive depending on the power supply phase;
a control circuit alternately conducting detection of the magnetic pole and power supply for drive of the motor by said driving circuit when a rotating speed of the motor is less than a predetermined speed; and
a back electromotive force detecting circuit detecting a back electromotive force on said field coil so as to determine the power supply phase when the rotating speed of the motor is greater than said predetermined speed, with drive of the motor being executed based on a detection result of the back electromotive force detecting circuit.
2. A drive control system according to claim 1,
wherein the field coils of all phases undergo the detection phase during a first period for detection of the magnetic pole position, the field coil of only one phase is selected to undergo the detection phase in a next period for detection of the magnetic pole position.
3. A drive control system according to claim 1, further comprising a reset circuit provided to reset detection parameters when said detection of the magnetic pole position fails and to re-try said detection of the magnetic pole position after said reset.
4. A drive control system according to claim 1, further comprising a rotor position control circuit provided to shift the rotor’s position with an open loop control when the detection of the magnetic pole position fails for a predetermined number of times, and to re-try said detection of the magnetic pole position after said open loop control.
5. A drive control system according to claim 1,
wherein when conditions of the induced voltages detected in each phase are all identical or when amplitudes of the induced voltages detected in all phases are smaller than a predetermined threshold value, said detection of the magnetic pole position is judged to have failed.
6. A drive control system according to claim 1,
wherein the detection of said induced voltage is executed by accumulating a plurality of detected values obtained in a predetermined detection period and condition of the induced voltage is judged using an accumulated value generated by accumulating the plurality of detected values.
7. A drive control system according to claim 1,
wherein a circuit is also provided to logically judge, when an amplitude of an induced voltage obtained in any detection phase of said induced voltage is less than the threshold value, the magnetic pole position based on a normally detected induced voltage from a preceding magnetic pole position detection.
8. A drive control system according to claim 1,
wherein prior to a detection of said induced voltage, an offset voltage is detected from the field coil to undergo the detection phase, and only an induced voltage component is detected in the detection phase by subtracting a detected value of the offset voltage from a detected value of the induced voltage.
9. A drive control system according to claim 1,
wherein said induced voltage is converted to a digital value, such digital conversion is executed a plurality of times for every detection phase, and the results of the digital conversion are used as the detected value.
10. A drive control system according to claim 1,
wherein condition setting parameters for a detection of the magnetic pole position are stored in a programmable non-volatile memory, and contents of the programmable non-volatile memory can be updated or manipulated from an external side via a serial inputoutput port.
11. The controller of claim 1, further comprising a commutation circuit, and wherein the back electromotive force is a voltage induced on the another field coil.
12. A motor controller comprising:
a test power supply constructed to energize a first coil of a plurality of coils in a motor with test power;
a detection circuit constructed to detect an induced voltage caused by the test power supply on a second coil of the plurality of coils;
a position determination circuit constructed to determine a magnetic pole position of the motor based on the induced voltage;
a drive power supply constructed to supply drive power to the motor based on the magnetic pole position when a rotational speed of the motor is less than a predetermined speed;
a back electromotive force detection circuit constructed to detect a back electromotive force to control the drive power to the motor when the rotational speed of the motor is greater than said predetermined speed.
13. The controller of claim 12, wherein the test power is a pulse current.
14. The controller of claim 12, wherein the test power is a pulse current insufficient to drive the motor.
15. The controller of claim 12, wherein the position determination circuit can detect the magnetic pole position when the rotational speed of the motor is insufficient to detect the back electromagnetic force.
16. The controller of claim 12, wherein during a start-up period, the test power supply supplies test power to each coil of the plurality of coils in succession, and the induced voltage is detected on another of the plurality of coils.
17. The controller of claim 12, further comprising an open loop controller constructed to rotate the motor in the event that the magnetic pole position cannot be detected.
18. The controller of claim 12, wherein the supply of the drive power is alternated with detection of the magnetic pole position.
19. The controller of claim 12, wherein the motor is a sensor-less multi-phase motor.
20. A motor drive control system, comprising:
a three-phase and sensor-less motor;
a field coil;
a magnetic pole position detection unit that detects an amplitude of a voltage induced in the field coil in a no power feeding phase based on a variation in mutual inductance while current is supplied to at least one other phase of the motor, the magnetic pole position detection unit further detecting the magnetic pole position based on the detected amplitude;
a commutation Unit;
a drive unit that, based on the magnetic pole position, determines a drive phase in which a drive current to generate a torque of the motor is fed to the field coil; and
a sequencer unit that alternately executes a detection operation of the magnetic pole position and a drive operation so that the drive current is supplied to the field coil in the drive phase to execute an initial acceleration.
21. A motor drive control system according to claim 20,
wherein the sequencer unit is adapted to execute an initial acceleration operation including:
detecting the magnetic pole position of the field coil in all phases so as to detect an initial value of the magnetic pole position, and
detecting the magnetic pole position of the field coil in only one phase based on the initial value of the magnetic pole position.
22. A motor drive control system according to claim 20, wherein the sequencer unit resets detection parameters when said detection of the magnetic pole position fails in order to re-try said detection of the magnetic pole position after said reset.
23. A motor drive control system according to claim 20, wherein the sequencer unit executes a control to shift a rotor’s position with an open loop control when the detection of the magnetic pole position fails for a predetermined number of times, and to re-try said detection of the magnetic pole position after said open loop control.
24. A motor drive control system according to claim 20, wherein when conditions of induced voltages detected in each phase are all identical or when amplitudes of induced voltages detected in all phases are smaller than a predetermined threshold value, said detection of the magnetic pole position is judged to have failed.
25. A motor drive control system according to claim 20, wherein the detection of the amplitude of the voltage induced in the field coil includes integration of a plurality of values obtained during a predetermined detection phase.
26. A motor drive control system according to claim 20, wherein when the amplitude of the voltage induced in the field coil obtained in any detection phase is less than a threshold value, the sequencer unit logically judges the magnetic pole position based on a normally detected induced voltage from a preceding magnetic pole position detection.