Abstract:
An electronic apparatus ( 1 ) supported against a dog&#39;s skin to control vocalizing by the dog electronically converts the vocalizing into a sequence of signals representing frequencies of the vocalizing, and operates a controller to determine if each measured frequency lies within any of a plurality of predetermined frequency sub-ranges and if so, increments cumulative totals of the frequencies which lie in the sub-ranges, respectively, to provide a plurality of cumulative totals that represent a frequency spectrum of the vocalizing. The controller is operated to determine whether the barking sounds constitute a valid bark by comparing the frequency spectrum to a predetermined valid bark frequency spectrum. Appropriate aversive stimulus signals are produced between first and second stimulus electrodes if the vocalizing sounds constitute a valid bark.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates generally to collar-mounted electronic “bark limiter” or dog bark training devices, and more particularly to improvements therein to provide improved, more reliable sensing of vibration due to vocalization and barking of the dog, and also relates to sensing of what constitutes “valid” barking. 
   A variety of electronic dog training collars have been utilized for applying electrical shock and/or audible stimulus to a dog when it barks. In many situations it is highly desirable to prevent individual dogs or groups of dogs from barking excessively. For example, one dog&#39;s barking in a kennel is likely to stimulate other dogs to bark. This is undesirable with respect to the welfare of the dogs themselves and nearby people. Similar problems occur in neighborhoods in which there are dogs that are kept outside at night: if one dog starts barking others are likely to join in, causing a general disturbance. 
   The closest prior art is believed to include the present assignee&#39;s Bark Limiter product and commonly assigned U.S. Pat. No. 4,947,795 by G. Farkas entitled “Barking Control Device and Method”, issued Aug. 14, 1990 and incorporated herein by reference. U.S. Pat. No. 4,947,795 discloses a bark training device which includes circuitry in a collar-mounted electrical device that detects the onset of barking and initially produces only a single low level electrical stimulus pulse that gets the dog&#39;s attention, but does not initially produce a highly unpleasant level of stimulation. If the dog continues barking, the stimulation levels of the electrical shock pulses are increased at the onset of each barking episode in a stepwise fashion until the stimulus becomes so unpleasant that the dog stops barking for at least a predetermined time, e.g., one minute. After that minute elapses, the circuitry resets itself to its lowest initial stimultion level and remains inactive until barking begins again, and then repeats the process, beginning with the lowest level of stimulation and increasing the stimulus level if barking continues. 
   A shortcoming of the all of the prior art bark training products is that they detect nearly any sound the dog makes which exceeds a certain level and then automatically applies aversive electrical stimulus to the dog in response to the detected sound. This reduces the effectiveness of the training, or even causes the training to become counterproductive. 
   SUMMARY OF THE INVENTION 
   Accordingly, it is an object of the invention to provide an improved animal training device that does not automatically apply aversive electrical stimulus to the dog in response to the detected sound unless the detected sound is accurately determined to be a “valid” barking sound. 
   Briefly described, and in accordance with one embodiment, the present invention provides a method of operating an electronic apparatus ( 1 ) to control vocalizing by a dog, wherein the electronic apparatus includes a housing ( 2 ) supported against the animal&#39;s skin, first and second stimulus electrodes ( 5 ) connected to a surface ( 9 ) of the housing, a sensor ( 6 ) supported by the housing for producing signals in response to vocalizing by the dog, and control circuitry, including a controller ( 33 ), in the housing having an input coupled to an output of the sensor, the control circuitry including output terminals coupled to produce aversive stimulus signals between the first and second stimulus electrodes in response to vocalizing by the dog. The method includes electronically converting vocalizing sounds from the dog into a sequence of corresponding signals representing the frequencies of the vocalizing sounds, providing the sequence of signals as an input to the controller, and operating the controller to determine the frequencies of the sequence of signals during a predetermined interval of time, to determine if each measured frequency lies within any of a plurality of predetermined frequency sub-ranges and if so, to increment cumulative totals of the frequencies which lie in the sub-ranges, respectively, to provide a plurality of cumulative totals that represent a frequency spectrum of the vocalizing sounds. The controller to is operated to determine whether the barking sounds constitute a valid bark by comparing the frequency spectrum to a predetermined valid bark frequency spectrum. Appropriate aversive stimulus signals are produced between the first and second stimulus electrodes if it is determined that the vocalizing sounds constitute a valid bark. 
   In the described embodiment, the range of frequencies is from 150 hertz to 800 Hz, and there are 16 contiguous sub-ranges within the 150 hertz At all to 800 Hz range, and the predetermined interval of time is approximately 120 milliseconds. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a collar-mounted bark limiter unit of the present invention with the collar removed. 
       FIG. 2  shows the a partially-exploded view of the bark under unit of  FIG. 1 . 
       FIG. 3A  is a perspective exploded view of the bark limiter unit of  FIGS. 1 and 2 . 
       FIG. 3B  is a side exploded view of the bark limiter unit as shown in  FIG. 3A . 
       FIG. 4  is a schematic diagram of the circuitry included in the housing of the bark limiter of  FIG. 1 . 
       FIGS. 5A and 5B  constitute a flowchart of software executed by the microcontroller  33  included in  FIG. 4 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   A preferred embodiment of a dog bark limiter of the present invention includes vibration transducer for providing signals representing vocalization or barking by the dog and control circuitry including a controller or processor that executes a capture and compare program to determine if the vocalization by the dog constitutes a “valid” bark. To accomplish this, the controller generates a frequency spectrum of the signals and compares it with a predetermined frequency spectrum to determine if the signals represent a “valid” bark. 
   Referring to  FIGS. 1 ,  2 ,  3 A and  3 B, bark limiter  1  includes a housing  2  having a lower section  2 A and an upper section  2 B. The top surface  9  of upper housing section  2 B is slightly concave, to better accommodate the curvature of a dog&#39;s neck. A pair of collar-retaining loops  3  are attached to opposite ends of upper housing section  2 B, as shown. A typical dog collar (not shown) is passed through loops  3  around the bottom surface of housing  2  to fasten bark limiter  1  to the dog&#39;s neck. Two stimulus electrodes  5  are threaded into receiving holes  8  ( FIG. 2 ) in the upper surface  9 , and their conductive tips are pressed against the dog&#39;s neck to make electrical contact therewith when the collar is tightened. As indicated in  FIG. 2 , stimulus electrodes  5  are removable. A preferably non-conductive stabilizing post of the same height as stimulus electrodes  5  is rigidly attached to upper surface  9 , and is offset from a straight line between stimulus electrodes  5  so the stabilizing post  7  to prevent the conductive electrode tips of stimulus electrodes  5  from “rocking” against the dog&#39;s neck. 
   A dome-shaped membrane  6  that preferably is integrally formed with the upper housing section  2 B is disposed on upper surface  9  and constitutes part of an improved vibration sensor  30 , which is subsequently described in more detail with reference to  FIG. 4 . Membrane  6  is approximately 0.035 inches in thickness. A membrane switch  17  extends through an opening  4  in upper surface  9 . The above features, except the stimulus electrodes  5 B and  5 C, on the upper surface  9  of upper housing  2 B are all integrally formed as a single unit. 
   Referring to the exploded views of  FIGS. 3A and 3B , lower housing section  2 A is attached to upper housing section  2 B by means of two screws  12 . A printed circuit board  15 A contained within housing  2  is attached to upper housing section  2 B by means of two screws  16 . A 3 volt lithium battery  13  is attached to the bottom of printed circuit board  15 A by means of a pair of clips  14 . The membrane switch unit  17  is attached to the upper surface of printed circuit board  15 A and extends through hole  4  in upper surface  9 . A metal trace  17 A is contacted to provide a switch closure when the upper surface of membrane switch unit  17  is depressed. An output transformer  18 , a microcontroller  19 , and five light emitting diodes D 1 – 5  are mounted on the upper surface of printed circuit board  15 . As shown in  FIG. 3B , a piezoelectric transducer  21  is supported on output transformer  18 , and is contacted by a “nipple”  11  ( FIG. 5 ) formed on the underside of dome-shaped membrane  6 . Piezoelectric transducer  21  can be a Model P/N: 7BB-20-6 available from Murata Electronics North America, Inc. 
   The dog owner can repetitively depress membrane switch  17  to select one of five stimulus intensity levels. The intensity indicators  10 - 1 , 2 , 3 , 4 , 5  become illuminated by light emitting diodes D 1 – 5 , respectively, as membrane switch  17  is successively depressed. The five LEDs correspond to indicators  10 - 1 , 2 , 3 , 4 , 5  to indicate which stimulation level has been selected by means of the membrane switch  17 , and also indicate whether the bark limiter  1  is in a test mode. Holding switch membrane  17  depressed for 4 seconds sets the bark limiter  1  into its test mode, and the various LEDs D 1 – 5  blink, depending on the neck motion and barking by the dog. The LED corresponding to the intensity level selected by means of membrane switch  17  is the one which blinks. 
   By way of definition, the term “housing” as used herein is intended to encompass any suitable container structure and/or encapsulation material that is used to contain the components of bark limiter  1 . The term “bark limiter” is intended to encompass similar devices that detect sounds from animals other than dogs. The bark limiter could be held by a strap against the chest, rather than the neck of an animal. 
   Referring to  FIG. 4 , the circuitry of bark limiter  1  is provided on the upper surface of printed circuit board  15 A ( FIG. 3A ), and includes vibration sensor assembly  30  which includes above mentioned dome-shaped membrane  6 , piezoelectric transducer  21 , and the above-mentioned nipple  11  formed on the underside of membrane  6  in order to efficiently transmit vibrations from membrane  6  to piezoelectric transducer  21 . One of the electrodes of piezoelectric transducer  21  is connected to ground and the other is coupled by capacitor C 4  and resistor R 10  to the (−) input of an operational amplifier  31 . The (+) input of operational amplifier  31  is connected to the junction between resistor R 12  and resistor R 13 . The other terminal of resistor R 12  is connected to ground, and the other terminal of resistor R 13  is connected to one terminal of resistor R 4  and to the RA 0  input on lead  19  of microcontroller  33 . The other terminal of resistor R 4  is connected to the battery voltage VBAT. 
   The output of operational amplifier  31  is connected by conductor  32  to the RA 2  input on lead  1  of microcontroller  33  and also is connected to one terminal of capacitor C 2  and one terminal of resistor R 5 . The other terminals of resistors R 5  and capacitor C 2  are connected to the (−) input of operational amplifier  31 . The RA 2  input of microcontroller  33  is connected to one input of an internal comparator, the other input of which is connected to the RA 0  terminal of microcontroller  33 , in order to produce an internal square waveform to be used as an input to the internal microprocessor portion of microcontroller  33 , to allow the frequency of the square waveform to be determined. The capacitor C 2  functions as a low pass filter that sets the upper cutoff frequency of operational amplifier  31 . The resistors R 5  and R 10  to determine the gain of operational amplifier  31 . 
   Voltage monitor circuit  34  in  FIG. 4  produces a low output voltage if VBAT is less than approximately 2 volts, applies a reset signal to the microcontroller reset input MCLR on lead  4  thereof if VBAT is below approximately 2 volts. The output of the internal comparator of microcontroller  33  is produced on lead  2  of microcontroller  33 , which is externally connected to the CCP 1  input on lead  2  of microcontroller  33 . The CCP 1  input of microcontroller  33  is used in the subsequently described compare-capture mode of operation, to measure the periods of the square waveforms on the CCP 1  input. This allows the signals produced by vibration transducer  30  and amplified by operational amplifier  31  to be captured within an approximately 120 millisecond interval and, in effect, captured within an approximately 120 millisecond interval and assembled into a frequency spectrum including sixteen 40 Hz windows in the range from 150 Hz to 800 Hz, which can be used to determine if the present sound is a valid bark. 
   Actuation of the motion sensor  40  in  FIG. 4  results in a signal applied to lead  7  of microcontroller  33  to indicate whether the dog&#39;s present neck motion is of the kind characteristically caused by barking. Microprocessor  33  automatically switches from low-power standby operation at 37 kHz to normal operation at 4 MHz if this signal indicates that the dog has begun barking. 
   The RA 6  output on lead  17  of microcontroller  33  is coupled to the base of an NPN transistor Q 1  having its emitter connected to ground and its collector coupled by a resistor R 6  to the base of a PNP transistor Q 2  having its collector connected to VBAT and its emitter connected by conductor  38  to one terminal of the primary winding of output transformer  42 . The base of transistor Q 2  also is coupled by a resistor R 2  to VBAT. The RA 7  output on lead  18  of microcontroller  33  is coupled to the base of an NPN transistor Q 3  which has its collector coupled by resistor R 7  to VBAT and its emitter connected to the base of an NPN transistor Q 4 . The emitter of transistor Q 4  is connected to ground and its collector is connected to conductor  38 . The other terminal of the primary winding of output transformer  42  is connected to VBAT. The secondary winding terminals  5 B and  5 C are connected to the two stimulus electrodes  5 . Transistor Q 4 , when turned on, produces a constant collector current for the entire amount of time that transistor Q 4  is turned on. If all of the collector current of transistor Q 4  flows through the primary winding of transformer  42 , that results in delivery of a maximum amount of energy to the primary winding of transformer  42  and therefore in a maximum amount output energy delivered to the stimulus electrodes  5  by the secondary winding of transformer  42 . However, if transistor Q 2  is turned on after the peak of the flyback spike that occurs in the waveform of the voltage V 38  on conductor  38  immediately after transistor Q 4  is turned off, then some of the decaying current in the primary winding of transformer  42  is shunted, causing V 38  to rapidly fall to zero. This reduces the amount of energy delivered to the primary winding of transformer  42  for each pulse of the waveform V 39  applied to the base of transistor Q 4  by microcontroller  33 , and therefore also reduces the amount of stimulus energy delivered through stimulus electrodes  5  to the dog&#39;s neck. Microcontroller  33  operates to produce a burst of pulses which are applied to the base of transistor Q 4  via the Darlington circuit configuration including transistor. 
   The microcontroller  33  used in the improved bark limiter  1  of the present invention preferably is a PIC16F628 available from Microchip Technology Incorporated, which includes several signal conditioning operational amplifiers, and operates so as to perform the same functions of executing the program represented by the flowchart of  FIGS. 5A and 5B . Microcontroller  33  includes a flash memory, a random access memory for storing file registers, and a non-volatile EEPROM for storing the operating program and valid bark detection algorithms. Microcontroller  33  also includes a comparator which generates the signal Data In, and also includes a Vref circuit that produces 1 of 16 voltage levels provided as inputs to the comparator input if the comparator input is configured so that a Vref input is needed. 
   By way of definition, the terms “controller” and “microcontroller” are used herein is intended to encompass any microcontroller, digital signal processor (DSP), logic circuitry, state machine, and/or programmed logic array (PLA) that performs functions of microcontroller  33  as described above. 
   Motion sensor  40  can be a Model #SQ-SEN-001P Ultra Compact Tilt and Vibration Sensor, available from SignalQuest Inc. Motion sensor  40  is of a mechanical ball-in-tube construction, and includes a conductive ball that makes contact with appropriate electrodes in response to motion of the dog&#39;s neck in order to send the “wake-up” signal microcontroller  33 . The assignee has discovered that dogs move their heads in a characteristic manner when they bark, and that using motion detector  40  improves accuracy in detection of “valid” barking. Specifically, the assignee has discovered that when dogs bark, they tend to move their heads and upper torso in a specific motion/pattern motion that can be detected by the above described motion detector  40 , although in some instances other types of motion detectors might be used. Motion patterns that are characteristic of barking can be detected using motion detector  40  and, in accordance with the present invention, a captured digitized bark signal can be utilized to provide a frequency spectrum that represents a “valid” bark in order to provide more accurate bark detection that has previously been achieved. 
   The present invention provides an improved technique of bark detection with software by using the internal “Capture/Compare module” of the PIC16LF627 microcontroller  33  to determine “valid” barks. During a 120 ms (or similar) capture time interval, the periods of the various bark signal frequencies are measured and counted. A window of acceptable frequencies in the range of, for example, 150 Hz–800 Hz, is created by the software. This interval or “window” is divided into 16 “buckets” into which the counts of 16 evenly divided frequency ranges are stored. When a bark/sound signal is received, the periods of the bark frequencies are measured during the 120 ms capture interval. The period of the frequency component of the received bark/sound signal is measured, and if the measured period falls within one of the 16 buckets, i.e. frequency ranges, then a software counter assigned to that bucket is incremented. For each complete bark signal/sound captured, the counter totals are compared to predetermined threshold levels for each corresponding bucket, respectively in order to determine whether the bark/sound constitutes a “valid” bark. 
     FIG. 5A  shows how bark limiter  1  is awakened from its “SLEEP” mode in response to a motion-indicating interrupt signal from motion detector  40 , as indicated in decision block  71 . If a motion signal is received by microcontroller  33 , the program goes from decision block  71  to block  75  and checks to determine if any sound or vibration signal is being received on conductor  32  in response to vibration sensor  30 . In decision block  76 , the program executes the subroutine of  FIG. 5B  to determine if the spectrum of sound signals received from vibration sensor  30  is the spectrum of a “valid bark”. If this determination is affirmative, the program executes a routine to cause the circuitry including transistors Q 1 , Q 2  and Q 3  and transformer  42  to generate an aversive electrical stimulus signal of a selected intensity between stimulation electrodes  5 B and  5 C. 
   Referring again to  FIG. 5A , if the decision of block  76  is that no valid bark is occurring, the program goes to block  77  and causes the LED corresponding to the selected stimulation level to flash twice, and then goes to decision block  78  and determines if a signal from motion detector  40  indicates that a significant neck motion is occurring. If this determination is affirmative, the program returns to the entry point of block  75  to determine if a bark signal is being received from vibration sensor  30 . If the determination of block  78  is negative, the program goes to blocks  79  and  80  and determines if a 2 second interval elapses without neck motion being detected, and if this happens, the program causes microcontroller  33  to go into its sleep mode, as indicated in block  81 . 
   If the determination of decision block  71  is negative, the program goes to decision block  72  and determines if switch  17  is depressed. If switch  17  is not depressed, the program causes microcontroller  33  to go into its sleep mode. If decision block  72  determines that switch  17  is depressed, the program responds in block  74  by determining and storing the new desired stimulus level established by repetitive depressing of switch  17 . Specifically, in block  74  the program determines if switch  17  is depressed for more than 1 second, and if this is the case, increments the stimulation level setting from the present level setting (1–5) to the next level setting and saves the new stimulus level setting. 
   The routine performed in decision block  76  of  FIG. 5A  is shown in  FIG. 5B . Referring to  FIG. 5B , in block  190  the program switches the internal oscillator clock frequency of microcontroller  33  from 37 kHz to 4 MHz and then goes to block  191  and starts a 120 millisecond timer, to create a 120 millisecond window within which the frequency spectrum of a “valid bark”, if present, is to be “captured”. The program then goes to decision block  192  and tests the output of the 120 millisecond timer, and after the 120 millisecond window elapses, the program goes to block  192 A and runs a subroutine to determine if the vocalization detected is a valid bark. This is accomplished by comparing the number of times the frequency of the detected vocalization is captured in each frequency range or “bucket” within the 120 millisecond window with a predetermined number of times for each bucket. The program then goes to block  193  and switches the internal oscillator clock frequency of microcontroller  33  back to 37 kHz to provide low power ON mode operation. The program then returns to the entry point of decision block  76  of  FIG. 5A . 
   If block  192  determines that the 120 milliseconds timer is still counting, the program then goes to decision block  195  and determines if there is a change in the level of the signal on leads  2  and  10  of microcontroller  33  to indicate that a “pulse” is present. If this determination is negative, the program reenters the entry point of decision block  192 , but if the presence of the pulse is detected, the program goes to block  196  and measures the duration of the pulse, and in block  197  increments the frequency spectrum “bucket” or counter which corresponds to the period (i.e., frequency) measured in block  196 . The program then reenters decision block  192  and continues the process until the 120 millisecond timer elapses. The “pulse” referred to is generated on lead  2  of microcontroller  33  from an internal comparator therein and is provided as an input to lead  10  of microcontroller  33 , which is the “capture and compare” (CCP 1 ) input of microcontroller  33 , and automatically starts a timer at the beginning of the pulse and stops the timer at the end of the pulse, so the frequency of the signal coming from vibration sensor  30  is thereby determined and can be used to select the appropriate frequency spectrum bucket to be incremented in order to acquire the frequency spectrum of the present bark signals received from vibration sensor  30  by one input of the internal comparator referred to. Lead  2  of microcontroller  33  is the output of that comparator. The reference applied to the other input of the internal comparator is established by the voltage on lead  19  by the resistive voltage divider circuitry shown in  FIG. 4 . 
   Note that it is important that the dog not be accidentally electrically stimulated if it rubs against something or if miscellaneous vibration is picked up by the vibration sensor  30 . 
   While the invention has been described with reference to several particular embodiments thereof, those skilled in the art will be able to make the various modifications to the described embodiments of the invention without departing from its true spirit and scope. It is intended that all elements or steps which are insubstantially different from those recited in the claims but perform substantially the same functions, respectively, in substantially the same way to achieve the same result as what is claimed are within the scope of the invention.