WO2011055255A1

WO2011055255A1 - Method and system for revoking a fall alarm field of the invention

Info

Publication number: WO2011055255A1
Application number: PCT/IB2010/054696
Authority: WO
Inventors: Ningjiang Chen; Sheng Jin; Constant Paul Marie Jozef Baggen
Original assignee: Koninklijke Philips Electronics N.V.
Priority date: 2009-11-03
Filing date: 2010-10-18
Publication date: 2011-05-12

Abstract

This invention presents a system and a method for revoking a fall alarm of a user after the fall is detected. The system comprises an altimeter, an accelerator, a processor and a controller. The altimeter and the accelerator worn by the user acquire a plurality of parameters relating to the fall. The processor processes the plurality of parameters to determine a posture change of the user within a first predefined period after the fall is detected. The controller revokes the fall alarm when the posture change indicates that the user has stood up. By processing the parameters acquired by the altimeter and the accelerator worn by the user, the posture change of the user, such as the user has stood up, can be determined. And then the fall alarm can be revoked when the posture change indicates that the user has stood up. In this way, unnecessary actions for dealing with the fall alarm can be avoided to save manpower and material resources.

Description

METHOD AND SYSTEM FOR REVOKING A FALL ALARM

FIELD OF THE INVENTION

The invention relates to fall detection, in particular to a method and system for revoking a fall alarm of a user after the fall is detected.

BACKGROUND OF THE INVENTION

Many people are at increased risk of injury or death as a result of a chronic health condition or complications resulting from acute illness, disability, or advancing age. Many other people suffer from chronic, or at least sustained, conditions that require

long-term treatment. Other people, such as soldiers, police, fire fighters, rescue workers, etc., work under hazardous and life-threatening conditions. In many instances, detecting a fall of these individuals is necessary to render aid when needed in order to prevent further health issues that could result from a fall.

WO2004/047039 discloses a method and a device for fall prevention and detection, especially for the elderly care, based on digital image analysis using an intelligent optical sensor. The fall detection is divided into two main steps: finding the person on the floor, and examining the way in which the person ended up on the floor. The first step is further divided into algorithms investigating the percentage share of the body on the floor, the inclination of the body and the apparent length of the person. The second step includes algorithms examining the velocity and acceleration of the person. When the first step indicates that the person is on the floor, data for a time period of a few seconds before and after the indication is analyzed in the second step. If this indicates a fall, a countdown state is initiated, in order to reduce the risk of false alarms, before sending an alarm.

SUMMARY OF THE INVENTION

When a user is monitored by a fall detection system, a fall alarm may be sent to family members of the user. These family members may have to rush to the user from other places and try to provide help to the user. The inventors of the present invention have realized that a user who has fallen may get up by himself/herself after the fall alarm has been issued. Although the fall alarm is correctly issued when the fall is detected, the fall alarm is not valid when the user has managed to get up after falling. In this case, because the user has become well, the fall alarm is unnecessary and the family member need not rush to the user's aid when the family member is in a place far away from the user.

In addition, when the fall alarm is sent to a call center having a medical service provider that takes care of a lot of patients, it will reduce the work efficiency of the health service provider if a lot of time is spent on patients who have stood up by themselves after falling down.

Even if the fall alarm can be revoked by the users manually, because the users are usually patients or elderly people, the users may incorrectly revoke the fall alarm or forget to revoke the fall alarm.

The method provided by WO2004/047039 can only reduce the risk of false alarms by initiating a countdown state and cannot contribute to checking the validity of a correctly issued fall alarm and thus revoke it if the user has stood up after the fall.

Based on an understanding of the prior art and the problems described above, it would be advantageous to revoke a fall alarm of a user after the fall is detected, without any operation by the user being required. It would also be desirable to revoke the fall alarm in a reliable way.

To better address one or more of the above concerns, according to an embodiment of a first aspect of the invention, a system for revoking a fall alarm of a user after the fall is detected is proposed. The system comprises:

an altimeter and an accelerator, intended to be worn by the user, for acquiring a plurality of parameters relating to the fall;

a processor for processing the plurality of parameters to determine a posture change of the user within a first predefined period after the fall is detected; and

a controller for revoking the fall alarm when the posture change indicates that the user has stood up.

The basic idea is to check whether the fall alarm remains valid by monitoring the posture change of the user after the fall is detected. By processing the parameters acquired by the altimeter and the accelerator worn by the user, the posture change of the user, such as the user has stood up, can be determined. And then the fall alarm can be revoked when the posture change indicates that the user has stood up. In this way, the fall alarm can be revoked without any operations by the users being required and unnecessary actions for dealing with the fall alarm can be avoided, thereby saving manpower and material resources.

According to an embodiment of a second aspect of the invention, a call center for providing medical service to a user is proposed. The call center comprises:

a receiver for receiving a fall alarm relating to a fall of a user and for further receiving a revoking message indicating the user has stood up within a predefined period after the fall is detected;

a processor for storing and analyzing the received fall alarm and the revoking message to update the user's profile; and

an interface for notifying that the fall alarm has been received or that the revoking message has been received.

By storing and analyzing the received fall alarm and the revoking message, the user's profile can be updated so that a reference can be provided for the future medical service to the user. By notifying that the fall alarm has been received or that the revoking message has been received, a person or an organization which are notified, can timely provide effective service to the user and can better arrange the work schedule to improve the work efficiency.

According to an embodiment of a third aspect of the invention, a method of revoking a fall alarm of a user after the fall is detected is proposed. The method comprises:

acquiring a plurality of parameters relating to the fall by means of an altimeter and an accelerator intended to be worn by the user;

processing the plurality of parameters to determine a posture change of the user within a first predefined period after the fall is detected; and

revoking the fall alarm when the posture change indicates that the user has stood up. According to an embodiment of a fourth aspect of the invention, a method of providing medical service to a user is proposed. The method comprises:

receiving a fall alarm relating to a fall of a user and further receiving a revoking message indicating the user has stood up within a predefined period after the fall is detected;

storing and analyzing the received fall alarm and the revoking message to update the user's profile; and

notifying that the fall alarm has been received or that the revoking message has been received.

These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.

DESCRIPTION OF THE DRAWINGS

The above and other objects and features of the present invention will become more apparent from the following detailed description considered in connection with the accompanying drawings, in which:

Fig.l depicts a block diagram of the system in accordance with an embodiment of the invention;

Fig.2 depicts a schematic diagram of posture changes of the user after the user has fallen down;

Fig.3 depicts a block diagram of the system in accordance with another embodiment of the invention;

Fig.4 depicts a block diagram of the call center in accordance with an embodiment of the invention;

Fig.5 depicts a flow chart of the method in accordance with an embodiment of the invention; and

Fig.6 depicts a flow chart of the method in accordance with another embodiment of the invention.

The same reference numerals are used to denote similar parts throughout the Figures. DETAILED DESCRIPTION

According to an embodiment of a first aspect of the invention, a system for revoking a fall alarm of a user after the fall is detected is proposed. All the operations described hereinbelow are carried out after the fall is detected, i.e. after the user has fallen down.

Fig.1 depicts a block diagram of the system 100 in accordance with an embodiment of the invention.

Referring to Fig.l, the system 100 comprises an altimeter 110 and an accelerator 120, intended to be worn by the user, for acquiring a plurality of parameters relating to the fall after the fall is detected.

The altimeter 110 can be implemented in many ways. For example, the altimeter 110 is a barometric altimeter which acquires an altitude value based on a measured atmospheric pressure value. The altitude value acquired by the altimeter 110 can be a height above different kinds of references, such as a height above a sea level, a height above a ground level or a height above a preferred position, etc.

The accelerator 120 can be implemented in many ways. For example, the accelerator 120 is a three-dimensional accelerator which can acquire three acceleration values of the accelerator 120 in three dimensions.

Generally, the altimeter 110 and the accelerator 120 can be worn by the user via a holding fixture, such as a band, a clamp, etc. The altimeter 110 and the accelerator 120 can alternatively be worn by the user by placing them in a portable device, such as a mobile phone, an mp3 player, etc.

Because the altimeter 110 and the accelerator 120 are worn by the user, the plurality of parameters acquired by the altimeter 110 and the accelerator 120 represent characteristics of the body movements of the user, and thus the user's body status can be derived irrespective of whether the user moves or keeps still. The plurality of parameters relating to the fall can be any one of the following parameters: acceleration, altitude, etc. Both the magnitude and the direction of the acceleration can be measured. Because the plurality of parameters is acquired after the fall is detected, the plurality of parameters show the body movements of the user after falling. The system 100 further comprises a processor 130 for processing the plurality of parameters to determine a posture change of the user within a first predefined period after the fall is detected.

Fig.2 depicts a schematic diagram of posture changes of the user after the user has fallen down.

Referring to Fig.2, posture changes 211 to 214 show an exemplary process of posture changes after the user has fallen down: firstly, the user lies on the ground with his face downward; secondly, the user rises with his face toward the ground; thirdly, the user sits up on his knees; and finally, the user fully stands up. Posture changes 221 to 224 show another exemplary process of posture changes after the user has fallen down: firstly, the user lies on the ground with his face upward; secondly, the user rises with his face upward; thirdly, the user sits up on one hip; and finally the user sits in a chair.

The processor 130 determines the posture change, based on the plurality of parameters, in many ways. For example, the plurality of parameters comprise at least one altitude change value acquired by the altimeter 110, and the processor 130 determines the posture change as "the user has stood up" when one altitude change value, i.e. the increase of the altitude, exceeds an altitude change threshold, such as 0.8 meter. For another example, the plurality of parameters comprise at least one altitude change value acquired by the altimeter 110 and at least one acceleration magnitude value acquired by the accelerator 120; the processor 130 determines the posture change as "the user is sitting in a chair", when one altitude change value exceeds an altitude change threshold, such as 0.5 meter, and one acceleration magnitude value exceeds an acceleration magnitude threshold, such as 20 meter per square second.

The first predefined period can be determined in many ways. For example, the first predefined period is determined by estimating the duration from the moment the user falls to the moment he stands up. For another example, the first predefined period is determined by estimating the duration from the moment the user falls to the moment the user sits in a chair. In addition, the first predefined period may neither be too long, since help must be timely provided to a user who cannot move after falling, nor too short, to allow determining the posture change which shows that the user is still well after falling. Optionally, the first predefined period can be determined according to the age of the user, for example, the first predefined period is relatively longer for an elderly person. Preferably, the first predefined period ranges from 20 seconds to 40 seconds.

The system 100 further comprises a controller 140 for revoking the fall alarm when the posture change indicates that the user has stood up.

For a user who has fallen down, there are many kinds of posture changes, such as "standing up" or "sitting in a chair", which can show that the user has become well and does not need help. In the present invention, for the sake of simplicity, all the posture changes which show that the user has become well and does not need help are defined as the posture change indicating that the user has stood up. The controller 140 revokes the fall alarm when the posture change indicates that the user has stood up, i.e. when the posture change indicates that the user has become well and does not need help.

Because the posture change of the user is monitored within the first predefined period after the fall is detected, it is possible to check the validity of the fall alarm, based on the determined posture change. In this way, unnecessary actions for dealing with the fall alarm can be avoided, thereby saving manpower and material resources.

Fig.3 depicts a block diagram of the system in accordance with another embodiment of the invention.

Referring to Fig.3, the system 100 further comprises a transmitter 310 for transmitting a message to a call center, which provides medical service to the user, to revoke the fall alarm if the determined posture change indicates that the user has stood up and the fall alarm has been transmitted to the call center.

Optionally, the transmitter 310 is adapted for transmitting a message to the call center to confirm the fall alarm if the fall alarm has been transmitted to the call center and if it is determined that there is no posture change indicating that the user has stood up within the first predefined period after the fall is detected.

Based on the message transmitted by the transmitter 310, the call center can better plan the next step of action. For example, the call center can call back rescue personnel if the call center receives the message to revoke the fall alarm. The processor 130 can set the posture change as "standing up", based on the plurality of parameters, in many ways. The processor 130 sets the posture changes showing that the user has become well and does not need help as "standing up".

In an embodiment of the processor 130, when the plurality of parameters comprise a plurality of altitude change values of the altimeter 110 and a plurality of acceleration magnitude values of the accelerator 120, the processor 130 sets the posture change as "the user has stood up" when one altitude change value exceeds a first threshold and one acceleration magnitude value exceeds a second threshold.

The plurality of altitude change values can be acquired by the altimeter 110 in many ways. For instance, the altimeter 110 acquires ten altitude values Al to A10 separately at ten time points Tl to T10, and the altitude change value corresponding to one time point is derived by subtracting the minimal altitude value acquired before the time point from the altitude value acquired at the time point. For example, when the minimal altitude value before time point T7 is A3, the altitude change value corresponding to time point T7 is the differential value between A7 and A3.

As described above, the user may have different kinds of posture changes, such as "lying", "rising", "sitting up" and "standing up", after falling down. The altitude change between every two posture changes is different. For example, the altitude change between "lying" and "rising" is about 0.3 meter and the altitude change between "lying" and "standing up" is about 0.8 meter. The first threshold can be determined according to the possible altitude changes, i.e. the increase of the altitude, between "lying" and "standing up". Therefore, by comparing each altitude change value with the first threshold, it can be determined whether the user has become well (e.g. whether the user has stood up), i.e. the posture change of "standing up" can be set when one altitude change value exceeds the first threshold. Optionally, the first threshold can be determined according to the height of the user. Preferably, the first threshold ranges from 0.6 meter to 1 meter.

However, there may be a big error in an altitude value acquired by the altimeter 110. For example, when the altimeter 110 acquires an altitude value based on an atmospheric pressure value measured by the altimeter 110, the measured atmospheric pressure value may deviate substantially from the real atmospheric pressure due to the effect of an air flow, wind or air conditioning. Therefore, in order to set the posture change in a reliable way, it is required to set the posture change of "standing up" based on not only the altitude change values but also other values. Because the user may move his body substantially during the process from the posture change of "falling down" to the posture change of "standing up", and the determination of a substantial body movement can be done based on the plurality of acceleration magnitude values of the accelerator 120, the setting of the posture change of "standing up" can also be done based on the plurality of acceleration magnitude values.

The plurality of acceleration magnitude values can be acquired by the accelerator 120 in many ways. For example, the acceleration magnitude value is calculated by equation 1 , wherein ACMi is the acceleration magnitude value sampled at time point i and ACMix , ACMiy and ACMiz are three acceleration magnitude values of the accelerator 120 in three dimensions. For another example, the acceleration magnitude value is calculated by equation 2, wherein ACMi is the acceleration magnitude value derived for time point i , ACMjx , ACMjy and ACMjz are three acceleration magnitude values of the accelerator 120 in three dimensions and are sampled at time point j , g is the gravitational acceleration, Ta is the time for averaging the acceleration magnitude value and Fs is the sample frequency of the acceleration magnitude value. How to derive the acceleration magnitude value is not the purpose of the present invention and is not elaborated here.

ACMi = ACMix² + ACMiy² + ACMiz² Equation 1

i+Ta«Fs/2 .

ACMi = ∑ ( j ACMjx² + ACMjy² + ACMjz² - g)² /(Ta · Fs) Equation 2

j≡i-Ta*Fs/2

By comparing each acceleration magnitude value with the second threshold, it can be determined whether the magnitude of the user body movement is large enough, i.e. the posture change of "standing up" can be further set when one acceleration magnitude value exceeds the second threshold. In general, the time point when one acceleration magnitude value exceeds the second threshold is before the time point when one altitude change value exceeds the first threshold. The second threshold can be determined based on the algorithm for calculating the acceleration magnitude values. For example, when the acceleration magnitude values are calculated by equation 2, the second threshold ranges from 10 (m/s 2 2 to 40 (m/s 2 2.

Because the posture change of "standing up" is set based on both the altitude change values and the acceleration magnitude values, the fall alarm is revoked in a more reliable way.

In another embodiment of the processor 130, when the plurality of parameters comprise a plurality of altitude change values of the altimeter 110 and a plurality of acceleration direction change values of the accelerator 120, the processor 130 sets the posture change as "the user has stood up" when one altitude change value exceeds the first threshold and one acceleration direction change value exceeds a third threshold.

In this embodiment, the monitoring of the altitude change value has been described above and is not further elaborated here. As described above, in order to set the posture change in a reliable way, it is required to set the posture change of "standing up" based on not only the altitude change values but also other values. Because the user may move his body substantially during the process, i.e. from the posture change of "falling down" to the posture change of "standing up", and the determination of a substantial body movement can be done based on the plurality of acceleration direction change values of the accelerator 120, the setting of the posture change of "standing up" can also be done based on the plurality of acceleration direction change values.

The plurality of acceleration direction change values can be acquired by the accelerator 120 in many ways. For example, the acceleration direction change value is calculated by equation 3, wherein ACDi is the acceleration direction change value derived for time point i , the symbol " o " means the calculation of the scalar product of two vectors, the symbol " | | " means the calculation of the norm of a vector, vec _ li and vec _ 2i are two vectors which are calculated by equation 4 and 5 separately. In equation 4 and 5, ac_ xj , ac_ yj and ac_ zj are three acceleration magnitude values of the accelerator 120 in three dimensions and are sampled at time point j , Ta is the time for averaging the acceleration magnitude value and Fs is the sample frequency of the acceleration magnitude value. How to derive the acceleration direction change value is not the purpose of the present invention and is not elaborated here. 180 . vec _ li o vec _ 2i .

ACDi = · arccos(_{j j}— : :) Equation 3

π vec li · vec 2i

^ ac _ xj /(Ta · Fs)

j =i-Ta*Fs

vec li ∑ac_ yj /(Ta » Fs) Equation 4

j =i-Ta*Fs

i

^ ac _ zj /(Ta · Fs)

j =i-Ta*Fs

i+Ta«Fs

^ ac _ xj /(Ta · Fs)

j=i

i+Ta«Fs

vec 2i ∑ac_ yj /(Ta » Fs) Equation 5

j J==iⁱ

i+ TTaa«*FFss

^ ac _ zj /(Ta · Fs)

J=ⁱ

By comparing each acceleration direction change value with the third threshold, it can be determined whether the direction change of the user body movement is large enough, i.e. the posture change of "standing up" can be further set when one acceleration direction change value exceeds the third threshold. In general, the time point when an acceleration direction change value exceeds the third threshold is before the time point when an altitude change value exceeds the first threshold.

The third threshold can be determined based on the algorithm for calculating the acceleration direction change values. For example, when the acceleration direction change values are calculated by equation 3, the third threshold ranges from 25 degrees to 45 degrees.

Because the posture change of "standing up" is set based on both the altitude values and the acceleration direction change values, the fall alarm is revoked in a more reliable way.

In a further embodiment of the processor 130, when the plurality of parameters comprises a plurality of altitude change values of the altimeter 110 and a plurality of acceleration magnitude change values of the accelerator 120, the processor 130 sets the posture change as "the user has stood up" when a first acceleration magnitude change value of the plurality of acceleration magnitude change values falls below a fourth threshold within a second predefined period after the fall is detected, a second acceleration magnitude change value of the plurality of acceleration magnitude change values exceeds a fifth threshold, and one altitude change value exceeds the first threshold. The time for deriving the second acceleration magnitude change value is in between the time for deriving the first acceleration magnitude change value and the time for deriving the altitude change value.

The time for deriving an altitude change value or an acceleration magnitude change value, is the time when the altitude change value or the acceleration magnitude change value is calculated or obtained by the sensor (altimeter 110 or accelerator 120) or the processor 130, i.e. when the altitude change value or the acceleration magnitude change value is available for determining the posture change of the user.

In a scenario of the posture change process described above, firstly, the user lies on the ground after falling down, and then the user rises from the lying position before finally standing up. Therefore, the posture change of "standing up" can be set in a more reliable way if both the altitude change and the posture change of "lying and then rising" can be monitored. The monitoring of altitude change has been described above and is not further elaborated here.

A solution for determining the posture change of "lying and then rising" is found by first determining the posture change of "lying" and then the posture change of "rising", based on the plurality of acceleration magnitude change values.

The acceleration magnitude change value can be derived in many ways by the accelerator 120. For example, the acceleration magnitude change value is calculated by equation 6, wherein ACQ is the acceleration change value derived for the time point i , ACj is the acceleration magnitude value sampled at time point j and T is the time window (such as 0.5 second) for deriving the acceleration magnitude change value. How to derive the acceleration magnitude change value is not the purpose of the present invention and is not elaborated here.

i i

ACCi = max ( ACj )- min( ACj ) Equation 6

j =i-T j =i-T

By comparing each acceleration magnitude change value with the fourth threshold within the second predefined period after the fall is detected, it can be determined whether the user body movement is small enough, i.e. the posture change of "lying" can be determined when one acceleration magnitude change value falls below the fourth threshold. Because the posture change of "lying" usually occurs in a short period after the user has fallen down, the second predefined period is applied to improve the accuracy of the determination of the posture change of "lying". Preferably, the second predefined period ranges from 3 seconds to 7 seconds.

By comparing each acceleration magnitude change value with the fifth threshold, it can be determined whether the user body movement is large enough, i.e. the posture change of "rising" can be determined when one acceleration magnitude change value exceeds the fifth threshold.

The fourth and fifth thresholds can be determined according to the algorithm for calculating the acceleration magnitude change values or the accuracy of the accelerator 120. The fourth threshold and the fifth threshold can be the same or different. For example, when the acceleration magnitude change values are calculated by equation 6, the fourth threshold and the fifth threshold both range from 0.2 m/s 2 to 0.4 m/s 2.

In this way, the posture change of "standing up" is set in a more reliable way when it is determined that the posture change of "lying and then rising" occurs first and then one altitude change value exceeds the first threshold.

The processor 130 can derive a plurality of altitude change values in many ways.

In an embodiment of the processor 130, when the altimeter 110 acquires a minimum altitude value of the altimeter 110 and a plurality of altitude values of the altimeter 110, and the accelerator 120 acquires a plurality of acceleration direction change values of the accelerator 120, the processor 130 derives the plurality of altitude change values by subtracting the minimum altitude value from the plurality of altitude values. The acquiring time for each altitude value is after one acceleration direction change value exceeds a sixth threshold and/or the acquiring time for the minimum altitude value is before one acceleration direction change value exceeds a seventh threshold. The method for calculating the acceleration direction change values of the accelerator 120 has been described above and is not further elaborated here.

During the process from "falling down" to "standing up", the maximal altitude value of the altimeter 110 usually occurs after the user moves his body for standing up. In addition, the posture change of "moving for standing up" can be determined when one acceleration direction change value exceeds the sixth threshold. Therefore, it is possible to reduce the errors in the calculation of the altitude change values by acquiring the altitude values, which are the minuend for calculating the altitude change values, after one acceleration direction change value exceeds the sixth threshold.

During the process from "falling down" to "standing up", the minimal altitude value of the altimeter 110 usually occurs before the user moves his body for rising from the lying position. In addition, the posture change of "moving for rising" can be determined when one acceleration direction change value exceeds the seventh threshold. Therefore, it is possible to reduce the error in the calculation of the altitude change value by acquiring the minimal altitude value, which is the subtrahend for calculating the altitude change values, before one acceleration direction change value exceeds the seventh threshold. In other words, before one acceleration direction change value exceeds the seventh threshold, the minimum of the altitude values of the altimeter 110 is set as the minimal altitude value.

The sixth threshold can be the same as the third threshold described above. Preferably, the seventh threshold is half of the sixth threshold.

In this way, only useful altitude values used for deriving the altitude change values are selected and then the errors in the acquired altitude values can be reduced.

In another embodiment of the processor 130, when the altimeter 110 acquires a minimum altitude value of the altimeter 110 and a plurality of altitude values of the altimeter 110, and the accelerator 120 acquires a plurality of acceleration magnitude values of the accelerator 120, the processor 130 derives a plurality of altitude change values by subtracting the minimum altitude value from the plurality of altitude values. The acquiring time for each altitude value is after one acceleration magnitude value exceeds an eighth threshold and/or the acquiring time for the minimum altitude value is before one acceleration magnitude value exceeds a ninth threshold. The method of calculating the acceleration magnitude values of the accelerator 120 has been described above and is not further elaborated here.

During the process from "falling down" to "standing up", the maximal altitude value of the altimeter 110 usually occurs after the user moves his body for standing up. In addition, the posture change of "moving for standing up" can be determined when one acceleration magnitude value exceeds the eighth threshold. Therefore, it is possible to reduce the errors in the acquired altitude values by acquiring the altitude values, which are the minuend for calculating the altitude change values, after one acceleration magnitude value exceeds the eighth threshold.

During the process from "falling down" to "standing up", the minimal altitude value of the altimeter 110 usually occurs before the user moves his body for rising. In addition, the posture change of "moving for rising" can be determined when one acceleration magnitude value exceeds the ninth threshold. Therefore, it is possible to reduce the error in the acquired minimal altitude value by acquiring the minimal altitude value, which is the subtrahend for calculating the altitude change values, before one acceleration magnitude value exceeds the ninth threshold. In other words, before one acceleration magnitude value exceeds the ninth threshold, the minimum of the altitude values of the altimeter 110 is set as the minimal altitude value.

The eighth threshold can be the same as the second threshold described above. Preferably, the ninth threshold is half of the eighth threshold.

In this way, only useful altitude values used for deriving the altitude change values are selected and the errors in the acquired altitude values can be reduced.

In a further embodiment of the processor 130, when the altimeter 110 acquires a minimum altitude value of the altimeter 110 and a plurality of altitude values of the altimeter 110, and the accelerator 120 acquires a plurality of acceleration magnitude change values of the accelerator 120, the processor 130 derives a plurality of altitude change values by subtracting the minimum altitude value from the plurality of altitude values. The acquiring time for the minimum altitude value is in between a first time point when one acceleration magnitude change value falls below a tenth threshold within the second predefined period after the fall is detected and a second time point when one acceleration magnitude change value exceeds an eleventh threshold after the first time point. The method of calculating the acceleration magnitude change values of the accelerator 120 has been described above and is not further elaborated here. How to determine the second predefined period has been described above and is not further elaborated here.

In a scenario of the posture change process described above, firstly, the user lies on the ground after falling down, and then the user rises from the lying position before finally standing up. In this scenario, the minimal altitude value of the altimeter 110 usually occurs after the user has fallen down and before the user rises. In addition, the posture change of "lying" can be determined when one acceleration magnitude change value falls below the tenth threshold within the second predefined period after the fall is detected, and the posture change of "rising" can be determined when one acceleration magnitude change value exceeds the eleventh threshold after the posture change of "lying" has been determined. Therefore, it is possible to reduce the error in the acquired minimal altitude value by acquiring the minimal altitude value, which is the subtrahend for calculating the altitude change values, during the time between the first time point and the second time point. In other words, during the time between the first time point and the second time point, the minimum of the altitude values of the altimeter 110 is set as the minimal altitude value.

The tenth threshold can be the same as the fourth threshold described above and the eleventh threshold can be the same as the fifth threshold describe above.

In this way, the error in the acquired minimal altitude value can be reduced.

In a further, other embodiment of the processor 130, when the altimeter 110 acquires a minimum altitude value of the altimeter 110 and a plurality of altitude values of the altimeter 110, and the accelerator 120 acquires a plurality of acceleration magnitude change values of the accelerator 120, the processor 130 derives a plurality of altitude change values by subtracting the minimum altitude value from the plurality of altitude values. When there is not any acceleration magnitude change value falling below the fourth threshold within the second predefined period after the fall is detected, a third time point is set as the acquiring time for the minimum among the altitude values acquired within a third predefined period after the fall is detected. The acquiring time for the minimum altitude value, which is the subtrahend for calculating the altitude change values, is within a fourth predefined period after the third time point. In other words, within the fourth predefined period after the third time point, the minimum of the altitude values of the altimeter 110 is set as the minimal altitude value.

Because the posture change of "lying" is not found out within the second predefined period after the fall is detected, it means that the user does not lie on the ground after falling down. Therefore, to make the altimeter 110 stable enough for acquiring the altitude values, the start time for measuring the minimal altitude value is set as the occurring time of the minimum of the altitude values acquired within the third predefined period after the fall is detected, and the process of looking for the minimal altitude value lasts throughout the fourth predefined period. Preferably, the third predefined period ranges from 1 second to 5 seconds, and the fourth predefined period ranges from 6 seconds to 10 seconds.

In this way, the error in the acquired minimal altitude values can be reduced.

In the above described embodiments, the acquiring time for an altitude value is the time when the altitude value is calculated or obtained by the sensor (altimeter or accelerator), i.e. when the value is available for determining the posture change of the user.

According to an embodiment of a second aspect of the invention, a call center for providing medical service to a user is proposed. .

Fig.4 depicts a block diagram of the call center 400 in accordance with an embodiment of the invention.

Referring to Fig. 4, the call center 400 comprises a receiver 410 for receiving a fall alarm relating to a fall of a user and for further receiving a revoking message indicating the user has stood up within a predefined period after the fall is detected. The revoking message can be transmitted in many ways, such as by means of the embodiment of the transmitter 310 described above. The predefined period can be determined in many ways, for example such as the first predefined period described above.

The call center 400 further comprises a processor 420 for storing and analyzing the received fall alarm and the revoking message to update the user's profile. The user's profile can be updated in many ways. For example, the user's profile records an event (such as falling or standing up after falling) and the corresponding time of the event. The processor 420 can analyze the received fall alarm and the revoking message in many ways. For example, the processor 420 calculates the frequency of the user's posture change of "falling" and "standing up after falling".

In this way, the user's profile can be used for formulating a plan for providing medical service to the user or it can be used as a reference for medical research.

The call center 400 further comprises an interface 430 for notifying that the fall alarm has been received or that the revoking message has been received. For example, the call center 400 has a service organization, which service organization sends a rescue person to help the user if the service organization is notified of the fall alarm, or the service organization calls back the rescue person if the service organization is notified of the revoking message. By notifying that the fall alarm has been received or that the revoking message has been received, an organization which is notified can provide effective service in a timely manner to the user and better arrange the work schedule to improve the work efficiency.

In an embodiment of the call center 400, the receiver 410 is adapted for receiving a plurality of parameters relating to the fall alarm or the revoking message. Based on the plurality of parameters, it is determined that either a fall has occurred or that a fall alarm should be revoked. The plurality of parameters can comprise many kinds of values, such as altitude values of the altimeter worn by the user and/or acceleration values of the accelerator worn by the user.

In this way, the movement characteristics of the user can be obtained based on the plurality of parameters. In addition, the algorithm for determining a fall or revoking a fall alarm can be improved if the service provider finds that the real user status is different from the information (such as the fall alarm and the revoking message) sent to the call center 400.

According to an embodiment of a third aspect of the invention, a method of revoking a fall alarm of a user after the fall is detected is proposed. All the operations to be described below are carried out after the fall is detected.

Fig.5 depicts a flow chart of the method in accordance with an embodiment of the invention.

Referring to Fig.5, the method comprises a step 510 of acquiring a plurality of parameters relating to the fall by means of an altimeter 110 and an accelerator 120 intended to be worn by the user.

The method further comprises a step 520 of processing the plurality of parameters to determine a posture change of the user within a first predefined period after the fall is detected.

The method further comprises a step 530 of revoking the fall alarm when the posture change indicates that the user has stood up.

In an embodiment of the method, the method further comprises a step of transmitting a message to a call center, which provides medical service to the user, to revoke the fall alarm if the determined posture change indicates that the user has stood up and the fall alarm has been transmitted to the call center. In another embodiment of the method, the method further comprises a step of transmitting a message to the call center to confirm the fall alarm if the fall alarm has been transmitted to the call center and it is determined that there is not any posture change indicating the user has stood up within the first predefined period after the fall is detected.

The step 520 of processing can be implemented in many ways to set the posture change of

"standing up".

In an embodiment, when the plurality of parameters comprise a plurality of altitude change values of the altimeter 110 and a plurality of acceleration magnitude values of the accelerator 120, the step 520 of processing comprises setting the posture change as "the user has stood up" when one altitude change value exceeds a first threshold and one acceleration magnitude value exceeds a second threshold.

In another embodiment, when the plurality of parameters comprise a plurality of altitude change values of the altimeter 110 and a plurality of acceleration direction change values of the accelerator 120, the step 520 of processing comprises setting the posture change as "the user has stood up" when one altitude change value exceeds a first threshold and one acceleration direction change value exceeds a third threshold.

In a further embodiment, when the plurality of parameters comprise a plurality of altitude change values of the altimeter 110 and a plurality of acceleration magnitude change values of the accelerator 120, the step 520 of processing comprises setting the posture change as "the user has stood up" when a first acceleration magnitude change value of the plurality of acceleration magnitude change values falls below a fourth threshold within a second predefined period after the fall is detected, a second acceleration magnitude change value of the plurality of acceleration magnitude change values exceeds a fifth threshold, and one altitude change value exceeds a first threshold. The deriving time for the second acceleration magnitude change value is in between the deriving time for the first acceleration magnitude change value and the deriving time for the altitude change value.

The step 520 of processing can be implemented in many ways to derive a plurality of altitude change values.

In an embodiment, the plurality of parameters comprise a minimum altitude value of the altimeter 110, a plurality of altitude values of the altimeter 110 and a plurality of acceleration direction change values of the accelerator 120, and the step 520 of processing comprises deriving a plurality of altitude change values by subtracting the minimum altitude value from the plurality of altitude values. The acquiring time for each altitude value is after one acceleration direction change value exceeds a sixth threshold and/or the acquiring time for the minimum altitude value is before one acceleration direction change value exceeds a seventh threshold.

In another embodiment, the plurality of parameters comprise a minimum altitude value of the altimeter 110, a plurality of altitude values of the altimeter 110 and a plurality of acceleration magnitude values of the accelerator 120, the step 520 of processing comprises deriving a plurality of altitude change values by subtracting the minimum altitude value from the plurality of altitude values. The acquiring time for each altitude value is after one acceleration magnitude value exceeds an eighth threshold and/or the acquiring time for the minimum altitude value is before one acceleration magnitude value exceeds a ninth threshold.

In a further embodiment, the plurality of parameters comprise a minimum altitude value of the altimeter 110, a plurality of altitude values of the altimeter 110 and a plurality of acceleration magnitude change values of the accelerator 120, the step 520 of processing comprises deriving a plurality of altitude change values by subtracting the minimum altitude value from the plurality of altitude values. The acquiring time for the minimum altitude value is in between a first time point when one acceleration magnitude change value falls below a tenth threshold within a second predefined period after the fall is detected and a second time point when one acceleration magnitude change value exceeds an eleventh threshold after the first time point.

According to an embodiment of a fourth aspect of the invention, a method of providing medical service to a user is proposed.

Fig. 6 depicts a flow chart of the method in accordance with another embodiment of the invention.

Referring to Fig. 6, the method comprises a step 610 of receiving a fall alarm relating to a fall of a user and further receiving a revoking message indicating the user has stood up within a predefined period after the fall is detected. The method further comprises a step 620 of storing and analyzing the received fall alarm and the revoking message to update the user's profile.

The method further comprises a step 630 of notifying that the fall alarm has been received or the revoking message has been received.

In an embodiment of the method, the method further comprises a step of receiving a plurality of parameters relating to the fall alarm or the revoking message. Based on the plurality of parameters, it is determined that a fall has occurred or that a fall alarm is revoked.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention and that those skilled in the art will be able to design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps not listed in a claim or in the description. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. In the apparatus claims enumerating several units, several of these units can be embodied by one and the same item of hardware or software. The usage of the words first, second and third, et cetera, does not indicate any ordering. These words are to be interpreted as names.

Claims

CLAIMS:

1. A system for revoking a fall alarm of a user after the fall is detected, comprising:

an altimeter (110) and an accelerator (120), intended to be worn by the user, for acquiring a plurality of parameters relating to the fall;

a processor (130) for processing the plurality of parameters to determine a posture change of the user within a first predefined period after the fall is detected; and

a controller (140) for revoking the fall alarm when the posture change indicates that the user has stood up.

2. A system as claimed in claim 1, wherein the plurality of parameters comprise a plurality of altitude change values of the altimeter (110) and a plurality of acceleration magnitude values of the accelerator (120), and

the processor (130) is adapted for setting the posture change as "the user has stood up" when one altitude change value exceeds a first threshold and one acceleration magnitude value exceeds a second threshold.

3. A system as claimed in claim 1, wherein the plurality of parameters comprise a plurality of altitude change values of the altimeter (110) and a plurality of acceleration direction change values of the accelerator (120), and

the processor (130) is adapted for setting the posture change as "the user has stood up" when one altitude change value exceeds a first threshold and one acceleration direction change value exceeds a third threshold.

4. A system as claimed in claim 1, wherein the plurality of parameters comprise a plurality of altitude change values of the altimeter (110) and a plurality of acceleration magnitude change values of the accelerator (120), and

the processor (130) is adapted for setting the posture change as "the user has stood up" when a first acceleration magnitude change value of the plurality of acceleration magnitude change values falls below a fourth threshold within a second predefined period after the fall is detected, a second acceleration magnitude change value of the plurality of acceleration magnitude change values exceeds a fifth threshold, and one altitude change value exceeds a first threshold, wherein the deriving time for the second acceleration magnitude change value is in between the deriving time for the first acceleration magnitude change value and the deriving time for the altitude change value.

5. A system as claimed in claim 1, wherein the plurality of parameters comprise a minimum altitude value of the altimeter (110), a plurality of altitude values of the altimeter (110) and a plurality of acceleration direction change values of the accelerator (120), and

the processor (130) is adapted for deriving a plurality of altitude change values by subtracting the minimum altitude value from the plurality of altitude values,

wherein the acquiring time for each altitude value is after one acceleration direction change value exceeds a sixth threshold and/or the acquiring time for the minimum altitude value is before one acceleration direction change value exceeds a seventh threshold.

6. A system as claimed in claim 1, wherein the plurality of parameters comprise a minimum altitude value of the altimeter (110), a plurality of altitude values of the altimeter (110) and a plurality of acceleration magnitude values of the accelerator (120), and

wherein the acquiring time for each altitude value is after one acceleration magnitude value exceeds an eighth threshold and/or the acquiring time for the minimum altitude value is before one acceleration magnitude value exceeds a ninth threshold.

7. A system as claimed in claim 1, wherein the plurality of parameters comprise a minimum altitude value of the altimeter(l lO), a plurality of altitude values of the altimeter (110) and a plurality of acceleration magnitude change values of the accelerator (120), and

the processor (130) is adapted for deriving a plurality of altitude change values by subtracting the minimum altitude value from the plurality of altitude values, wherein the acquiring time for the minimum altitude value is in between a first time point when one acceleration magnitude change value falls below a tenth threshold within a second predefined period after the fall is detected and a second time point when one acceleration magnitude change value exceeds an eleventh threshold after the first time point.

8. A system as claimed in claim 1, further comprising a transmitter (310) for transmitting a message to a call center, which provides medical service to the user, to revoke the fall alarm if the determined posture change indicates the user has stood up and the fall alarm has been transmitted to the call center.

9. A call center for providing medical service to a user, comprising:

a receiver (410) for receiving a fall alarm relating to a fall of the user and further receiving a revoking message indicating the user has stood up within a predefined period after the fall is detected;

a processor (420) for storing and analyzing the received fall alarm and the revoking message to update the user's profile; and

an interface (430) for notifying that the fall alarm has been received or that the revoking message has been received.

10. A method of revoking a fall alarm of a user after the fall is detected, comprising:

acquiring (510) a plurality of parameters relating to the fall by means of an altimeter (110) and an accelerator (120) intended to be worn by the user;

processing (520) the plurality of parameters to determine a posture change of the user within a first predefined period after the fall is detected; and

revoking (530) the fall alarm when the posture change indicates that the user has stood up.

11. A method as claimed in claim 10, wherein the plurality of parameters comprise a plurality of altitude change values of the altimeter (110) and a plurality of acceleration magnitude values of the accelerator (120), and the step of processing (520) comprises: setting the posture change as "the user has stood up" when one altitude change value exceeds a first threshold and one acceleration magnitude value exceeds a second threshold.

12. A method as claimed in claim 10, wherein the plurality of parameters comprise a plurality of altitude change values of the altimeter (110) and a plurality of acceleration direction change values of the accelerator (120), and the step of processing (520) comprises:

setting the posture change as "the user has stood up" when one altitude change value exceeds a first threshold and one acceleration direction change value exceeds a third threshold.

13. A method as claimed in claim 10, wherein the plurality of parameters comprise a plurality of altitude change values of the altimeter (110) and a plurality of acceleration magnitude change values of the accelerator (120), and the step of processing (520) comprises:

setting the posture change as "the user has stood up" when a first acceleration magnitude change value of the plurality of acceleration magnitude change values falls below a fourth threshold within a second predefined period after the fall is detected, a second acceleration magnitude change value of the plurality of acceleration magnitude change values exceeds a fifth threshold, and one altitude change value exceeds a first threshold,

wherein the deriving time for the second acceleration magnitude change value is in between the deriving time for the first acceleration magnitude change value and the deriving time for the altitude change value.

14. A method as claimed in claim 10, wherein the plurality of parameters comprise a minimum altitude value of the altimeter (110), a plurality of altitude values of the altimeter (110) and a plurality of acceleration magnitude change values of the accelerator (120), and the step of processing (520) comprises:

deriving a plurality of altitude change values by subtracting the minimum altitude value from the plurality of altitude values,

wherein the acquiring time for the minimum altitude value is in between a first time point when one acceleration magnitude change value falls below a tenth threshold within a second predefined period after the fall is detected and a second time point when one acceleration magnitude change value exceeds an eleventh threshold after the first time point.

15. A method of providing medical service to a user, comprising:

receiving (610) a fall alarm relating to a fall of the user and further receiving a revoking message indicating that the user has stood up within a predefined period after the fall is detected; storing and analyzing (620) the received fall alarm and the revoking message to update the user's profile; and

notifying (630) that the fall alarm has been received or that the revoking message has been received.