Activity measurement

A motion sensor unit (11) is intended to be carried by a domestic animal. The motion sensor unit (11) operates in parallel to and independently of a conventional transponder unit (1). The motion sensor unit (11) contains a motion detector (14) for measuring the activity of the animal by providing electrical pulses when the animal moves. Each hour is subdivided in a number of intervals in each one of which it is determined if the activity has exceeded a certain threshold. If it is the case, a count value is incremented. The count value is then transmitted once each hour and in addition also the count values of all the 23 previous hours. By transmitting repeatedly such information a good safety is obtained in the reception of the information signal, and this information can be used for complicated evaluation processing in a processor (7) or a supplementary personal computer (9).

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a method and a device for measuring the 
activity of domestic animals comprising an automatic transfer of 
measurement results to a central evaluation station. 
2. Description of the Prior Art 
Identification systems for domestic animals comprising a passive 
transponder unit attached to an animal have been widely used and the 
constructional details thereof have been elaborated. See e.g. U.S. Pat. 
Nos. 4,510,495, 4,247,758 and 4,618,861, and the International patent 
application having publication number WO 91/11678. 
In U.S. Pat. No. 4,510,495 a remote passive identification system is 
disclosed using a transponder responding to signals from a power 
transmitter. The animal identification and estrus detection system of U.S. 
Pat. No. 4,247,758 uses a transponder, that is a passive unit, which is 
interrogated and then transfers information of the number of movements of 
the animal. In the estrus detection system of U.S. Pat. No. 4,618,861 also 
a transponder is used, that obtains data from a self-powered motion 
sensor. Thus these two latter patents rely upon a transponder unit such 
that the animal estrus information about a particular animal can only be 
recorded when the animal passes near a transponder reader. For detecting 
estrus, the motion activity is determined or the fact whether the motion 
activity of the domestic animal has increased drastically is determined. 
Information of the result of the determination is communicated together 
with identification information for identifying the animal. 
An estrus detector using such method is also disclosed in the European 
patent having publication number EP-B1 0 087 015, but here an estrus 
detection tag is used, that is self-contained having a visual indication 
and no remote information transfer. Such a visual indication can be missed 
or not seen during a critical period. A similar self-contained estrus 
detector is also disclosed in U.S. Pat. No. 4,895,165 but there the 
general motion activity of the animal is not monitored. 
In the European patent application having publication number 0 549 081 
measurements of the activity of an animal are made by means of an 
implanted device powered by an internal electrochemical battery and 
comprising a motion sensor and a temperature sensor providing signals. The 
signals can be processed by a processor having a memory in the device to 
give some characteristic value. This can be made by storing successive 
measurement signals until a certain number of signals has been collected. 
Then the stored values are used for determining a characteristic value 
that is again stored, the used values being eliminated from the memory. 
Such characteristic values are stored during a time interval and are then 
transmitted. The length of the time interval can be determined by the time 
at which the animal is in the direct vicinity of a reception device. For 
storing successive measurement signals a substantial memory is required 
drawing a corresponding amount a electric power. The processing of signals 
inside the device requires a considerable amount of electric energy. 
In the published International patent application having publication number 
WO 95/32616 an electrochemical battery is used as a power source for the 
transmission of a signal indicating that the motion activity has 
increased. This design provides advantages such as a larger obtainable 
range for the transmitted signal. A disadvantage therein is that 
transmission is made only once and that it is not made sure that the 
signal is received by a centrally located station, for reasons such as the 
limited range of the transmitter, the fact that the animal can be at an 
unsuitable location when the transmission is made, etc. The transmitter of 
these data can also become non-operative and this condition will not be 
detected in this prior construction. 
SUMMARY OF THE INVENTION 
It is an object of the invention to provide a data collection and 
identification unit that can be used on an animal during a long time 
period and that transmits collected data safely to a central data 
processing station. 
It is a further object of the invention to provide a motion detector unit 
for an animal that transmits information that can be used for diagnosing 
various states of the animal. 
These objects are achieved by the invention hereof as more fully described 
below. 
Thus, generally, the animal is provided with some sensor means for 
monitoring the motion intensity of a domestic animal for detecting and 
transmitting different motion states of the sensor and thus also of the 
animal. The sensor is more or less rigidly attached to the animal. The 
sensor is assumed to be capable of detecting at least two different motion 
states, a first normal state and a second particular state, for instance 
some state involving relatively intense or frequent movements. A timer 
connected to a processor is provided for detecting the rate or frequency 
of the particular states. In particular the timer and processor are 
arranged so that at periodically repeated times having time intervals 
therebetween of a first predetermined length, it is determined whether the 
animal during the time interval from the next previous time has adopted 
the second, particular state and that the number of such times 
corresponding to the second, particular state are counted, when they 
occur. A transmitter is coupled to the processor for transmitting, at less 
frequent, periodically repeated times having time intervals therebetween 
of a second predetermined length that is larger than the first 
predetermined length, information of the determined rate or frequency to 
an evaluation station. Such information is in regard of the counted 
number, i.e. how many times after the previous transmission occasion it 
has been counted that the second state has been adopted. 
The particular feature of only counting states requires very little 
electric energy, compared to methods where complete measurement signals 
are stored before internal processing or transmission, compare the cited 
International patent application WO 91/11678 and European patent 
application 0 549 081. 
During or associated with each transmission to the evaluation station, 
information can also be transmitted in regard of the counted numbers 
during several time intervals before the present time. 
At the periodically repeated times, when information is transmitted to an 
evaluation station, identification information is then also advantageously 
transmitted for identifying the transmitter by the processor and thereby 
the sensor means and the animal. 
The timer means is thus arranged to provide first clock pulses of a first 
predetermined rate, having time intervals therebetween of a first 
predetermined length. The timer means also preferably provides second 
clock pulses of a second predetermined rate that is slower than the first 
rate, that is the second clock pulses being provided at less frequent, 
periodically repeated times having time intervals therebetween of a second 
predetermined length, that are thus larger than the intervals of the first 
predetermined length. 
The processor comprises memory means for storing at least one counted 
number. Furthermore, it comprises determining means coupled to the sensor 
means and the timer means for receiving the first clock pulses and for 
determining, at the reception of each first clock pulse, whether the 
animal during the time interval from the next previous time, when a first 
clock pulse was received, has adopted the second, particular state. The 
determining means are also coupled to the memory means for storing therein 
the number of such times when the second particular state has been 
adopted. The processor means has in addition control means coupled to the 
memory means, the timer means and the transmission means. The control 
means is arranged to control the transmission means for transmitting, at 
less frequent, periodically repeated times having time intervals 
therebetween of a second predetermined length, that is larger than the 
first predetermined length, information to the evaluation station in 
regard of the counted number stored in the memory means. 
The memory means can further be arranged for storing several counted 
numbers, and then the determining means are arranged to store counted 
numbers for at least two, and preferably a multitude of successive time 
intervals having the second predetermined length. The control means can 
then be arranged to also transmit, at the periodically repeated times when 
information is transmitted to the evaluation station, information in 
regard to the counted numbers during at least two time intervals having 
the second length, before the present time. 
The memory means may also be arranged to store an identification number or 
identification sequence. When so arranged, the control means are 
preferably arranged to also transmit, at the periodically repeated times 
when information is transmitted to the evaluation station, identification 
information derived from the stored identification sequence for 
identifying the transmitter and thereby the sensor means and the animal.

DETAILED DESCRIPTION 
In FIG. 1 a block diagram is shown illustrating an installation for 
identification and activity measurement of an animal, e.g. a domestic 
animal such as a dairy cow. In an evaluation station, that can be 
stationary, a processor unit 7 is located, which can possibly be coupled 
to a personal computer indicated at 9. The installation further comprises 
a motion sensor unit or activity measuring device 11 to be worn or carried 
by the animal. The activity measuring device 11 is arranged for 
transmitting information to the evaluation station. The measuring device 
11 emits radio frequency signals, that are to be received by an antenna 13 
connected to an interface 15. The interface 15 decodes the received 
information and transmits it to the processor 7, where the information is 
further processed, such as for generating some kind of alarm. 
The motion sensor unit 11 comprises as its core part a motion detector unit 
14 which can be the kind of electromagnetic sensor described in our 
previous International patent application PCT/SE95/00630, the disclosure 
of which is incorporated herein by reference. The motion sensor or 
detector 14 gives a signal having an amplitude depending on the motion 
intensity as is indicated by the curve of FIG. 2. Thus a more intense, 
faster or stronger movement gives a higher amplitude than a less intense, 
slower or weaker movement. The motion detector unit 14 comprises the 
actual motion sensor 14', which preferably is a simplified embodiment of 
the sensor disclosed in U.S. Pat. No. 5,183,056 for Bjorn Dalen et al., 
the sensor having a lower number of magnet poles. The electrical pulses 
from the motion sensor 14' can be shaped to a suitable varying electric 
voltage by a pulse forming procedure. The illustrated motion sensor 14' 
produces output signals of attenuated oscillation type comprising decaying 
pulses having some characteristic frequency. For shaping this signal it is 
provided to a low-pass filter 14" having a very low upper limit frequency 
of for example 28 Hz. The filtered signal is then amplified by an 
amplifier 14'" having a suitably chosen gain. 
In the motion sensor unit 11 there is also a processor unit, CPU 15, 
supplemented with additional units such as a read only memory (ROM) 17, a 
dynamic memory RAM 19 and a timer 21. The motion sensor unit 11 further 
comprises a comparator 23, a memory 25 for an identification number of the 
unit, an electrochemical battery 27, and an on/off-switch 29. Finally a 
radio frequency transmitter 31 is provided. The radio frequency 
transmitter 31 transmits signals on an antenna 32, for example in the 
shape of coil of conducting wire having a few turns or piece of straight 
wire located completely inside the measuring device 11. The various 
components of the sensor unit 11 are connected by conventional power 
supply lines and signal lines well understood by those skilled in the art 
and therefore all of them are not illustrated in the figure. 
The comparator 23 receives on one of its input terminals the signal 
V.sub.sense from the detector unit 14 and compares this signal to the 
voltage V.sub.ref received on its other input terminal. The reference 
voltage V.sub.ref is generated by voltage dividing the supply voltage of 
the electrochemical battery 27. The output signal of the comparator 23 is 
communicated to the processor 15, for example as an interrupt signal. It 
has a first level, an activity level, only when the output signal 
V.sub.sense of the detector unit 14 is larger than the reference voltage 
V.sub.ref and otherwise it stays at a second level indicating an inactive 
state. 
The timer circuit 21 is arranged to wake up the processor unit 15 256 times 
each hour, i.e. at times separated by intervals of approximately 14 
seconds. At these wake up times the processor determines whether the 
output signal V.sub.sense of the sensor 14, as compared by the comparator 
23, has been larger than a threshold value V.sub.ref set as another input 
signal to the comparator 23, shown by the time diagram of FIG. 2 
illustrating the smoothed output from the sensor 14'. As the comparator 
23, an operational amplifier may be used in the case where the sensor 
output signal is small. In any case, a flag is set in the dynamic memory 
19 when the sensor output signal V.sub.sense exceeds the predetermined 
threshold value V.sub.ref. 
Also, the wake up timer 21 must be supplied with current permanently. At 
each 14th second it thus wakes the processing unit 15 which then adds a 
one to a counter, also arranged inside the dynamic memory 19, in the 
circumstance where the sensor output signal has set the activity flag in 
the memory 19. In the opposite circumstance, the counter value is not 
modified. Then the central processor unit checks if it is time to transmit 
information. Preferably, this will be done once each hour. If it is time 
for a transmission, it will start the transmitter 31 and transmit the 
stored data. Suitable frequencies may be for example 433 MHz and 418 MHz. 
The stored data consist of the counted values for the last 24 hours, as 
shown in FIG. 3. There are thus 24 memory fields 33, each one holding a 
counted value (for example "185", "205", etc.). There is also an index 
pointer, stored in a memory field 34 of the RAM memory 19, which points to 
the counted value memory field 33, which was most recently updated. 
In FIG. 4 the format of the transmitted information block is illustrated, 
starting with a start field 41 telling the receiver that a new data block 
is coming. Then there is an RF-type field 43 following directly after the 
start field 41, the contents of this field identifying the type of message 
or type of transmitter, for instance that this is a message sent from an 
activity measuring device. After the type field 43, an identity number 
field 45 follows holding identity information as stored in the identity 
number storage means 25 and identifying the activity meter. After the 
identity field 45 there is a field 47 holding the value of the index 
pointer, as stored in the memory register 34. Field 47 points at the 
latest updated count memory field 33, this pointer value indicating 
approximately the hour of the day to which this transmission refers. Then 
follows the information stored in the memory means as counted value field 
49 for the counted values, that is the data stored in all the memory 
fields 33, and it comprises thus 24 partial fields having each one the 
length of one byte. The field thus holds information for the last 24 hours 
in a cyclical pattern, the number of the most recent hour or counted value 
being indicated by the value of the index pointer, as stored in the field 
47. Finally, there is a checksum field 51 following after the counted 
values field 49. This whole data block is transmitted very rapidly and 
only once per hour, so that a transmission period of a few hundreds of 
milliseconds is only required therefor. 
The information transmitted can then be received from the antenna 13 and 
the transmitted count values are processed in the processor 7. It will 
store the received counted values to make an evaluation thereof. A typical 
diagram of counted values as a function of time is plotted in FIG. 5 
illustrating the values of one week. Also plotted in this figure is a line 
illustrating a running mean or average calculated from the count values 
registered previously to each activity count. The activity is generally 
low in this example but a peak is obtained about the beginning of the day 
29/5. This peak may signal an estrus period. 
In FIG. 7 the function of the processor 15 is illustrated by a state 
diagram. The processor 15 and in particular the CPU thereof can take four 
states, A, B, C and D. 
The CPU will mostly be in state A, the quiescent or idling state. In this 
state the CPU is idle, just waiting for an interrupt. There are two kinds 
of interrupt which can wake up the CPU, either an activity interrupt, 
which is the same as an activity pulse, from the comparator 23 or a timer 
interrupt from the wake-up timer 21 meaning that a time period of 14 
seconds has elapsed. 
If there is an activity interrupt or activity pulse when the CPU is in 
state A and the interrupt is allowed, which means that the activity 
interrupt is the first one in the present time period of 14 seconds, the 
processor 7 will proceed to state B. In state B the counter 33 pointed to 
by the pointer 34 that counts the present activity pulses will be 
incremented by one step and then a flag is set which tells the processor 
that no other activity interrupt is allowed within this time period. When 
finished in state B the processor always go back to state A. If there is a 
timer interrupt and the current state is A the CPU will go to state C. In 
state C there will be a check whether one hour has elapsed since a RF 
transmission took place. If the latest RF transmission occurred less then 
one hour ago the processor will go back to state A, but before that 
activity interrupts will be allowed by resetting of the flag which 
controls this. If one hour has elapsed the next state will be D. 
In state D a RF transmission of the transmission block as indicated in FIG. 
6, will take place. After the transmission has finished the activity 
interrupt flag will be reset, allowing activity interrupts to take place, 
and the processor will go back to state A. 
The components of the motion sensor unit 11 which need a permanent current 
supply comprise the wake up timer 21, the refresh of the dynamic memory 19 
and the comparator 23. With a suitable dimensioning of the electronic 
circuits, a careful selection of voltages etc., the sensor unit 11 can be 
used for many years without requiring any replacement of the battery 27. 
Providing a transmission at periodic times, as described above, also 
provides other advantages, such as that it may be easily detected that the 
motion sensor unit 11 is not still operable. Also a low activity of the 
animal, to which the sensor is attached, can be recognized, such a low 
activity signalling possibly that the animal is in a bad condition, has 
some illness, etc. Also the feature of always transmitting the data of the 
last hours, such as described above the 24 last hours, makes it possible 
to reconstruct all counted values even in the case where some of the 
transmissions have not been received. 
The on/off switch 29 is necessary since in certain cases it may be required 
that the motion sensor unit should not emit any radiation, for example 
when the motion sensor is shipped to a distributor or end user. Also, 
energy of the electrochemical battery 27 can be saved in those cases where 
the motion sensor unit is to be stored before actually using it. The 
switch can preferably be designed as a magnetically operated reed switch, 
that is a switch that is controlled by an external magnet. Thus, such a 
switch does not require any mechanical connection to the outside from the 
interior of the activity meter 11. The activity measuring device can then 
be very well encapsulated and isolated electrically, without any 
electrically conductive parts extending from the exterior thereof to the 
outside, since also the antenna coupled to the transmitter can be totally 
encapsulated. 
A circuit diagram of the activity measuring device is shown in FIG. 8. The 
motion sensor 14' of the kind indicated above provides a signal having 
alternating polarities between the terminals of the sensor. One of the 
terminals is then locked to half the voltage of the supply voltage of 3 
volts. It is made by connecting one of the terminals to the midpoint of a 
symmetric voltage divider constructed of two equal resistors R1 and R2. 
Suitable series resistors R3, R5, R4 connect the terminals of the motion 
sensor 14' and the midpoint of the voltage divider to the inputs of a 
differential amplifier N1 that is connected both to act as a lowpass 
filter and to provide an amplification. This is made by a parallel 
combination of a capacitor C1 and a resistor R6 connected between that 
input of amplifier N1, that is not connected to have the potential of 1.5 
volts, and the output terminal of the amplifier N1. 
This output terminal of the amplifier N1 is also connected to the negative 
input terminal of a second differential amplifier N2 operating as the 
comparator 23. The other input terminal, the positive one, of this 
amplifier N2 is connected to the midpoint of a voltage divider circuit 
comprising resistors R7 and R8 to provide the voltage reference V.sub.ref. 
The other terminals of these resistors, which are not connected to each 
other at the midpoint, are connected to signal ground and the supply 
voltage of 3 volts. The output of the amplifier N2 is connected to an 
interrupt input terminal of the processor D1, 15 of type HD407A4369F that 
includes suitable ROM- and RAM-memories 17, 19 and a timer circuit 21, as 
indicated in FIG. 1. 
In the stationary processor 7, and in particular when a personal computer 9 
is used and connected thereto, the activity counts can be evaluated for 
finding different states of the considered animal. 
The activity measuring installation as described above can be used together 
with and in a device for separating animals as will be described 
hereinafter. 
In FIG. 6 a corral is shown comprising an area 53 for a herd of freely 
walking animals. In the following, reference will be made only to cows. It 
is however obvious that the devices and installations as described herein 
also can be applied to other animals, for example sheep and goats. The 
area 53 may for example be a barn or an area provided outdoors, which may 
be enclosed by a fence. In the area 53 an automatic milking station 55 and 
a separation device 57 are provided. The automatic milking station 55 
comprises a stall 59 having an entrance gate 61, an exit gate 63 and a 
milking machine 65 that is provided with a robot arm 67 for applying teat 
cups, not shown, on the teats of a cow present in the stall 59. The 
milking station 55 also comprises an identification device 69, for 
identifying a cow entering the milking stall 59 and an examination device 
71 for examining the condition of the animal with respect to illness, for 
example mastitis, blood in the milk, injuries on the udder and the teats. 
The examination device 71 or an additional examination device may be 
arranged outside the milking station 55. 
The separation device 57 comprises a separation zone 73 which is enclosed 
by an enclosure 75, for example a fence. In the separation zone 73 any 
kind of treatment may be performed on the cow which has been separated. 
The treatment might be any medical treatment, for example curing a disease 
by an injection. It might also be insemination or manual milking in the 
case that the automatic milking did not succeed. Finally it might be 
applying an earmark or even that the cow should be separated to be brought 
to slaughterhouse. In the enclosure 75 there are provided three entrance 
devices 77 and an exit gate 79 in particular manually operated but may 
alternatively be automatically operated, to permit removal of a cow from 
the separation zone 73. The entrance devices 77 are forming animal 
passages 81 leading from the area 53 to the separation zone 73. It should 
however be noted that more or less such entrance devices 77 might be 
provided. Each entrance device comprises a stall 77 having a front gate 83 
and a rear gate 85. In each stall 77 there is provided a feeding device 
87. Preferably the feeding device 87 is of the type which offers the cows 
concentrate to eat. Such feed is particularly attractive to the cows and 
therefore they frequently visit such feeding stalls. Moreover, when 
entering the stall 77 for eating concentrate, the cows need only to be 
present in the stall 77 for a short period of time in comparison to the 
circumstance when they eat ensilage that may continue for a long period of 
time. Furthermore an identification device 89 is provided at each entrance 
device for identifying a cow entering the stall 77. 
The entrance and exit gates 61, 63, the automatic milking machine 65, the 
identification device 69, the examination device 71, the front gates 83, 
the rear gates 85, the feeding devices 87 and the identification devices 
89 are controlled by the control and evaluation processor 7 of FIG. 1. 
The arrangement described above functions as follows. Voluntarily a cow 
which needs to be milked enters the milking station 55. There she is 
identified by the identification device 69, undergoes a condition 
examination by the examination device 71 and is milked by the automatic 
milking machine 65. The condition examination may be performed by optical 
means, not shown, to detect an external injury on the udder and the teats 
or that the udder and the teats are not clean. The condition examination 
may also be performed by measurements on the milk, in regard of for 
example conductivity or temperature for detecting diseased cows. 
Furthermore it is possible to measure the presence and the quantity of 
various kinds microbes in the milk. 
The result of the examination is stored and processed by the control 
processor 7. If the result does not indicate any defects the milk is 
delivered and the cow leaves the milking station 55 through the exit gate 
63 and enters the area 53. On the other hand, if the result indicates a 
disease or some other defect the milk is transported to a waste tank, not 
shown, and the cow is allowed to leave the milking station 55 through the 
exit gate 63 and enters the area 53. Furthermore if the robot arm 67 of 
the milking machine 65 does not succeed in bringing the teat cups on the 
teats the exit gate 63 is opened 50 so that the cow can leave the milking 
station 55 and enter the area 53. In the area 53, the cow is allowed to 
walk around freely and will after a while enter one of the feeding stalls 
77. If the examination result indicates that a specific cow should be 
separated due to any of the defects mentioned above, or due to the fact 
that a low activity of the cow has been detected by the motion sensor unit 
11 of FIG. 1 and this fact has been communicated to the stationary control 
processor 7, or that the cow should be inseminated because of high 
activity etc., the rear gate 85 will be closed when this specific cow has 
entered the stall 77 and is identified by the identification device 89. In 
the stall 77 the cow can be offered feed through the feeding device 87. 
However the front gate 83 is opened as commanded by the control processor 
7, that is not visible in FIG. 6 but, as has been already said, is 
supposed to control the various devices of the corral installation through 
suitable control lines or control channels, not shown. Thus the cow has to 
enter the separation zone 73. Thereafter the front gate 83 is closed and 
any treatment could be performed on the cow so separated. After the 
treatment the cow can be removed to the area 53 through the exit gate 79. 
For the cows which should not be separated the stalls 77 are functioning as 
normal feeding stalls, i.e. cows entering the stalls 77 for eating can 
after the eating has finished leave the stalls 77 in the backward 
direction, through the rear gates 85. Advantageously all of the feeding 
stalls 77 in the area 53 form passages 81 lead to the separation zone 73, 
since in this case the cows cannot avoid a feeding stall in which they can 
be separated.