Virtual fence based on animal direction

Abstract

The present invention relates to a method and a system for providing a virtual fence for grazing animals. The basis is tracking the position of grazing animals and exposing them to corrective signals when they move out of bounds, thereby creating a virtual fence. The invention incorporates directional sensors that measure the heading of the animal and uses this information to augment the use of position in the virtual fence. Heading can be found from the direction of the device, and is typically measured using a combination of a magnetometer, a gyroscope and an accelerometer. The position is typically measured using a GNSS device, but could also come from an inertial navigation system.

Description

[0001] Virtual fence based on animal direction.

[0002] TECHNICAL FIELD

[0003] The present invention relates to a method and system for creating a virtual fence and keeping grazing animals confined to a designated area.

[0004] BACKGROUND

[0005] Grazing animals, such as cows and horses, are often confined to specific areas by physical fences or barriers. However, such physical barriers can be expensive, difficult to maintain, and may interfere with natural grazing patterns. Virtual fences have been developed as an alternative, providing an electronic boundary that can be easily repositioned or removed as needed. Existing virtual fence systems often rely solely on position tracking, which can lead to latency in providing corrections to the animal and false alarms. There is a need for a more accurate and responsive virtual fence system for grazing animals.

[0006] There are several challenges related to virtual fences. They are used to keep grazing animals in a specific location without the use of physical fences. These typically track the position of the animal, and signal it when it moves out of bounds (typically using sound and electrical signals).

[0007] There exists several implementations and solutions to this general problem, but they typically only measure if the animal is inside or outside the designated area, and how far from the area.

[0008] Existing solutions typically only track position using a GNSS device. These position measurements are noisy and can drift over time. This can lead to the observed position moving when in reality the animal is standing still. If the device tries to signal the animal in these situations they can become confused since they aren’t doing anything.

[0009] Accurate GNSS measurements can also have a fairly slow update frequency, which means that the device can be slow to respond to the animal performing desired actions and giving the proper signals.

[0010] Therefore, there is a need for a system solving the above problems.

[0011] SUMMARY

[0012] In view of the above, an object of the present disclosure is to overcome or at least mitigate at least some of the drawbacks related to prior art. In particular, the present disclosure is related to a method for creating a virtual fence and keeping grazing animals confined to a designated area including a central processing unit and a device for measuring a position and a heading of each of the grazing animals, where the designated area is defined by a geographical boundary of the virtual fence, further including the steps of continuously monitoring position and heading of each of the grazing animals, defining a desired direction of a certain grazing animal as the direction from measured position towards the nearest point of the virtual fence if measured position is outside the geographical boundary, and as the direction from the nearest point of the virtual fence towards measured position if measured position is inside the geographical boundary. If monitored heading of a certain grazing animal has a vector component along the desired direction which is larger than a first predefined vector size, then exposing a first corrective signal to that certain grazing animal stimulating it to keep moving. If monitored heading of a certain grazing animal has a vector component along the opposite direction of the desired direction which is larger than a second predefined vector size, then exposing a second corrective signal to that certain grazing animal stimulating it to turn. The present disclosure also relates to a corresponding system adjusted to implement the above described method.

[0013] BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Illustrates an example of a virtual grazing area including a border area, a pasture, and a desired moving direction for a grazing animal outside or in the border area.

[0015] Figure 2 illustrates an example of defined inwards and outwards directions in relation to a desired moving direction,

[0016] Figure 3 is a flow chart of an example embodiment of the present invention.

[0017] DETAILED DESCRIPTION

[0018] The present invention relates to a method and a system for providing a virtual fence for grazing animals. The basis is tracking the position of grazing animals and exposing them to corrective signals when they move out of bounds, thereby creating a virtual fence. In addition, the invention also incorporates directional sensors that measure the heading of the animal and uses this information to augment the use of position in the virtual fence. Heading can be found from the direction of the device, and is typically measured using a combination of a magnetometer, a gyroscope and an accelerometer. The position is typically measured using a GNSS device, but could also come from an inertial navigation system.

[0019] The virtual fence system comprises a plurality of sensors fixed on the grazing animals in the grazing area to be fenced. The sensors can be of various types such as GNSS, or other position sensors. Each animal is also fitted with a directional sensor that measures the animal's heading. The sensors are connected to a central processing unit that manages the data from the sensors and controls the corrective signals to the animals.

[0020] According to one example of the present invention, the method of creating a virtual fence begins by defining the boundary of the grazing area. This can be done by setting up the sensors at the desired location and using GNSS or other position measurement techniques to determine the boundary of the area. Once the boundary is defined, the animals are fitted with the directional sensors and released into the grazing area.

[0021] Figure 1 Illustrates an example of a virtual fence zone enclosed by a virtual fence. A border area may be defined just inside the virtual fence, and a pasture, i.e. the desired gracing area, is defined within the border area. A desired moving direction for an animal being outside the area or in the border area is also indicated. The desired moving direction may be defined by an animal’s current position and the closest point on the virtual fence heading inwards towards the pasture.

[0022] As the animals graze, their position and heading are continuously monitored by the sensors. If an animal moves beyond the boundary of the grazing area, the central processing unit triggers a corrective signal to the animal. The corrective signal can be in the form of a sound or an electrical signal, or both. The corrective signal is used to guide the animal back to the grazing area / fence zone.

[0023] The directional sensors are used to augment the use of positions in the virtual fence zone. The heading information from the directional sensors is used to determine the animal's direction of movement. This information is used to only trigger the corrective signal when it is obvious from the heading that the animal is heading out of the fence zone. This reduces the number of false alarms and the stress on the animal. Additionally, the directional sensors allow for low-latency correction to the animal when it is outside of the fence zone, thereby reducing the time it takes for the animal to return to the grazing area.

[0024] Figure 2 illustrates an example of defined inwards and outwards directions in relation to a desired moving direction. The inwards sector defines the directions where an animal is defined to head inwards, and the outwards sector defines the directions an animal is defined to head inwards. Monitored heading directions within the outwards sector will trigger corrective signals exposed to the animal stimulating it to turn its direction into the inwards sector. Monitored heading directions within the inwards sector will either put corrective signals on hold or trigger a decrease of the frequency or intensity of the signal. The inwards sector may also be defined as the sector where the monitored direction’s vector component along the desired moving direction is larger than a predefined vector size.

[0025] According to one embodiment of the present invention, a device with sensors is placed on the neck of the grazing animal to measure its likely heading. The device could measure its direction, and therefore the direction of the animal, through the use of a magnetometer and an accelerometer. The accelerometer measures the instantaneous orientation of the device based on measuring gravity, and this orientation can be used together with the magnetometer to get out the compass direction of the device. This method provides a measurement of the heading of the device which we can use as an estimate for the heading of the animal to be used in the virtual fence according to the present invention.

[0026] A method based on only an accelerometer and a magnetometer will be very susceptible to noise in the measurements and movement of the device. According to other embodiments of the present invention, a gyroscope should typically be included, and the measurements from the three devices should be combined in a sensor fusion filter typically called an Attitude and Heading Reference System (AHRS), to make the heading measurement more stable . The gyroscope internally measures rotation of the device itself with high precision and high frequency, and with little interference from outside factors, and can therefore be used to create a more stable and low-latency direction estimate.

[0027] A rapid up-to-date measurement of direction makes it possible to respond to the animals movement quicker and create a better virtual fence with more immediate feedback to the animal. The fence mechanism described above can also be implemented by only using GNSS and position measurement to find the movement direction of the animal. This would result in a much slower system, where the animal would typically be required to move several meters before we get an updated estimate of their movement direction. The direction estimates would also in a lot of cases be much worse than the above mentioned sensor fusion approach. The movement measured by GNSS could be included as another factor in addition to the inertial sensors in an even more comprehensive sensor fusion filter for better performance at the cost of added complexity.

[0028] An example of how the present invention works is now described referring to the flow chart of figure 3, in particular the gray sketched area of the flow chart.

[0029] • When an animal is inside the fence, the system tracks its position / movement.

[0030] • When it gets outside a virtual fence line, or the system detects that it is about to, a correction is considered. First, the heading relative to the closest parts of the fence is checked. o If heading points outwards, corrective signals are activated. o If heading points inwards, activation of corrective signals are put on hold for a predefined period of time. This should minimize false positives for activating signals due to GNSS drift, and make the system easier to understand for the animals.

[0031] • After starting corrective signals, the animal needs to get back into the fence zone before it is disabled

[0032] • The corrective signals given are modulated based on the heading o Intensity is increasing if it points outwards o Intensity is decreasing if it points inwards o Upon turning, the intensity is immediately changed. This makes the system more responsive, and gives better feedback to the animals. According to further embodiments of the present invention, animals should undergo training before relying on the virtual fence to keep them contained within an area according to the present invention. The animals need to learn the signals given and how to correctly respond. To make it easier for the animals to understand the mechanism, it may be simplified. The start of the method works the same as disclosed above, but if the animal does the desired thing and changes to inwards mode, the signals are changed or stopped, similar to what would happen if they returned to the defined area. This gives the animals a much larger and more rapid response to turning in the desired direction. If they move outwards again the mechanism restarts.

[0033] According to yet another embodiment of the present invention, the animals are trained to respond to a first and a second corrective signal. When an animal is heading in a desired direction, the first corrective signal stimulating it to keep moving is exposed to the animal, and when the animal is heading in the opposite direction of the desired direction, the second corrective signal stimulating it to turn is exposed to the animal. The intensity of the signals may respectively depend on the size of the vector component of the heading direction along the desired direction and the opposite of the desired direction.

[0034] To facilitate automatic learning, the system keeps track of the animals’ response, and after a specified number of interactions with the fence where no electric pulse was given, the system changes to normal mode.

[0035] The system and method described in this invention offer several advantages over traditional fencing methods. The virtual fence system requires minimal physical infrastructure, and it can be deployed and dismantled quickly and easily. Additionally, the virtual fence system provides a more natural environment for the animals, as they are not confined by physical barriers. Furthermore, the system is scalable and can be used to fence large or small areas.

[0036] Grazing animals typically move forward, and their heading is a good indication of their intention. This makes it possible to reject a large number of invalid GNSS positions, and hold back on giving the animal signals when they have their back to the fence. This makes for a more robust solution with less false-positive signals.

[0037] Use of heading will also save power, since one can accept a lower update frequency for the position system in many situations when the animals have their back to the fence, and we can immediately throttle up the power hungry GNSS system if they turn towards the fence. When interacting with the virtual fence, having a measurement of the animal heading also makes it possible to give more immediate and nuanced feedback. The signals can be modulated immediately when the animals turn in the right or wrong direction without waiting for them to actually walk in that direction and that getting measured by the GNSS system.

[0038] It must be emphasized that the terminology "comprise / comprises" as used in this specification is chosen to specify the presence of stated features, numbers, steps or components, but does not preclude the presence or addition of one or more other functions, numbers, steps, components or groups thereof. It should also be noted that the word "a" or "an" preceding an element does not exclude the presence of a plurality thereof.

Claims

CLAIMS1. A method for creating a virtual fence and keeping grazing animals confined to a designated area including a central processing unit and a device for measuring a position and a heading of each of the grazing animals, where the designated area is defined by a geographical boundary of the virtual fence, characterized in the steps of:Continuously monitoring position and heading of each of the grazing animals,Defining a desired direction of a certain grazing animal as the direction from fmeasured position towards the nearest point of the virtual fence if measured position is outside the geographical boundary, and as the direction from the nearest point of the virtual fence towards measured position if measured position is inside the geographical boundary,If monitored heading of a certain grazing animal has a vector component along the desired direction which is larger than a first predefined vector size, then exposing a first corrective signal to that certain grazing animal stimulating it to keep moving,If monitored heading of a certain grazing animal has a vector component along the opposite direction of the desired direction which is larger than a second predefined vector size, then exposing a second corrective signal to that certain grazing animal stimulating it to turn.

2. A method according to claim 1, characterized in the following additional step:Defining a border area just within the geographical boundary of the virtual fence,If a certain grazing animal is inside the geographical boundary and outside border area, then putting all corrective signals on hold.

3. A method according to claim 1 , characterized in that the first corrective signal’s intensity increases as the vector component along the desired direction is increasing and decreases as the vector component along the desired direction is decreasing.

4. A method according to claim 1 , characterized in that the second corrective signal’s intensity increases as the vector component along the opposite direction of the desired direction is increasing and decreases as the vector component along the opposite direction of the desired direction is decreasing.

5. A method according to claim 1 , characterized in that the device for measuring a position and a heading includes a GNSS sensor, a magnetometer and an accelerometer.

6. A method according to claim 5, characterized in that the device for measuring the position and the heading also includes a gyroscope, and the measurements from the magnetometer and the accelerometer is combined in a sensor fusion filter in an Attitude and Heading Reference System (AHRS), making the heading measurement more stable.

7. A system for creating a virtual fence and keeping grazing animals confined to a designated area including a central processing unit and a measuring device for measuring a position and a heading of each of the grazing animals, where the designated area is defined by a geographical boundary of the virtual fence, characterized in that the central processing unit is adjusted to:Continuously monitoring position and heading of each of the grazing animals,Defining a desired direction of a certain grazing animal as the direction from measured position towards the nearest point of the virtual fence if measured position is outside the geographical boundary, and as the direction from the nearest point of the virtual fence towards measured position if measured position is inside the geographical boundary,If monitored heading of a certain grazing animal has a vector component along the desired direction which is larger than a first predefined vector size, then exposing a first corrective signal to that certain grazing animal stimulating it to keep moving,If monitored heading of a certain grazing animal has a vector component along the opposite direction of the desired direction which is larger than a second predefined vector size, then exposing a second corrective signal to that certain grazing animal stimulating it to turn.

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