WO2014199341A1

WO2014199341A1 - Device and method for detecting wear of a fall protection device

Info

Publication number: WO2014199341A1
Application number: PCT/IB2014/062185
Authority: WO
Inventors: Andrea Tonoli; Enrico Cesare ZENERINO; Roberto BONIN; Diego BOERO
Original assignee: Grivel S.R.L.
Priority date: 2013-06-12
Filing date: 2014-06-12
Publication date: 2014-12-18
Also published as: ITTO20130484A1

Abstract

Electronic device and method for detecting residual safety of fall protection device (specifically a harness for climbers) in terms of the accumulated force that the fall protection device has been subject to during falls of the climber. An accelerator measures the acceleration and a processing stage discriminates fall events as well as the maximum force occurring during each fall on the basis of the measured acceleration. Fall events are counted and the processing stage verifies, at each event of fall, whether a critical wear threshold of the fall protection device has been exceeded, on the basis of the accumulated maximum force values. When a critical threshold is reached, an alarm is given to the user that the equipment needs to be replaced. The device can be practically realised as a smartphone with an appropriate application that uses the accelerator built in the phone.

Description

"ELECTRONIC DEVICE WHICH CAN BE CONSTRAINED TO THE BODY OF A USER AND METHOD FOR DETECTING WEAR OF A FALL PROTECTION DEVICE" TECHNICAL FIELD

The present invention concerns an electronic device which can be constrained to the body of a user and is adapted to detect the wear of a fall protection device . In particular, the electronic device is adapted to detect the wear of a fall protection device connected to the user, for example a rope , a harness , an anchor or a quick draw. The present invention further refers to a method for detecting the wear of a fall protection device. BACKGROUND ART

As is known, in order to guarantee high safety standards for mountaineers, the need is felt for devices which allow accurate determination of the wear (equivalently, damage) of fall protection devices . For example , given any climbing rope , the need is felt to know the wear thereof , this wear being influenced by the number and entity of the falls to which the rope has been subj ected during its working life . Analogous considerations apply, for example , to the harnesses . Currently, the wear on mountaineering equipment is generally estimated empirically, by visual inspection by an expert . However, this method of estimating the wear requires specially qualified personnel , and is f rther of qualitative type . In fact , visual inspection does not in any way allow precise quantification of the wear; at the most it provides outline indications .

DISCLOSURE OF INVENTION

The obj ect of the present invention is therefore to provide an electronic device which solves at least partly the drawbacks of the known art . According to the present invention, an electronic device and a method for detecting the wear are provided, as defined in the attached claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the invention, embodiments are now described, purely by way of non- limiting example and with reference to the accompanying drawings, in which :

- figure 1 shows a block diagram of an embodiment of the present electronic device ;

figure 2 shows schematically an electronic unit of the present electronic device , coupled with a harness ;

figure 3 symbolically shows a mountaineer during a progression on a rock face ;

figure 4 shows a time trend of a signal generated by an accelerometer of the present electronic device;

- figure 5 shows the trend of the maximum number of events of fall that can be tolerated, as a function of the maximum force to which the mountaineering equipment is subj ect during the events of fall ;

- figure 6 shows a flow chart of operations performed by the present electronic device ;

figure 7 shows a block diagram of a further embodiment of the present electronic device ; and

figure 8 shows schematically a mobile phone in which the electronic unit shown in figure 2 is integrated .

BEST MODE FOR CARRYING OUT THE INVENTION

Figure 1 shows an electronic device 1 , which comprises a first and a second electronic unit 2 , 4.

As shown in figure 2, the first electronic unit 2 is adapted to be constrained to a harness 6 , of per se known type . The first electronic unit 2 may be permanently integrated with the harness 6, or may be coupled with the latter in a releasable manner, for example by means of Velcro. Furthermore, although reference is made below, without any loss of generality, to the case in which the first electronic unit 2 is constrained to the harness 6, it is also possible to constrain the first electronic unit 2 directly to the body of a generic user; for example, the first electronic unit 2 may be made integrally movable with, i.e. it can be fixed to, the body of a mountaineer by means of an elastic band (not shown) .

Given the above, the first electronic unit 2 comprises an accelerometer 8, a first processing unit 10, a battery 12, a memory 14, a light indicator 16 and a first communication stage 18.

The battery 12 is connected to the accelerometer 8, to the first processing unit 10, to the memory 14, to the light indicator 16 and to the first communication stage 18, so as to power them. The first processing unit 10 is connected bidirectionally to the memory 14 and to the first communication stage 18, which is of bidirectional type; the first processing unit 10 further controls the light indicator 16. The first processing unit 10 is therefore able to receive and transmit data, via the first communication stage 18.

In greater detail, in the embodiment shown in figure 1, the accelerometer 8, known per se, is of the triaxial type, and is therefore adapted to generate a measured electrical acceleration signal, which indicates the time trends of three components a_x, a_y and a_z, of the acceleration to which the accelerometer 8 is subject. The three components a_x, a_y, a_z are orthogonal to one another; furthermore, since the accelerometer 8 is integrally movable with the first electronic unit 2, and therefore with the harness 6 and the rope 34, these latter elements and the user are subject to the same acceleration as the accelerometer 8.

More specifically, the accelerometer 8 is for example of MEMS type and measures the relative acceleration of the accelerometer 8, with respect to a free-falling body. The three components a_x, a_y, a- therefore refer to a free-falling reference system .

The first processing unit 10 determines , on the basis of the measured electrical acceleration signal provided by the accelerometer 8, a modulus of acceleration signal M_A(t) , which indicates the modulus of the vectorial sum of the above- mentioned three components a_Xf a_y, a_z . Later on, this modulus is referred to as the modulus of acceleration to which the accelerometer 8 is subject, and is indicated by |a|.

The second electronic unit 4 comprises a second processing unit 20 and a second communication stage 22 , electrically connected to each other . Furthermore , the second electronic unit 4 comprises a user interface 24 , connected to the second processing unit 20.

The second communication stage 22 is of bidirectional type and is adapted to communicate with the first communication stage 18. Furthermore , both the first and the second communication stage 18 , 22 are preferably of the wireless type , although embodiments are possible in which they are adapted to allow wired communications . In practice , according to the embodiment shown in figure 1 , the first and the second processing unit 10 , 20 can exchange data, thanks to the interposition of the first and second communication stage 18 , 22 , each of which forms a corresponding transceiver .

Given the above , the first electronic unit 2 operates like a black box, which detects and stores the falls to which the harness 6 is subject, or more precisely the user of the harness 6. In particular, the figure 3 shows an example of a situation that can commonly occur during mountaineering, involving the presence of a mountaineer (user) 30 and a rock face (for example) 32. The mountaineer 30- wears the harness 6, has a mass m and is secured to the rock face 32, i.e. connected to the latter, by a rope 34 and an anchoring point 36. The anchoring point 36 is formed for example of a so-called spit, integral with the rock face 32, and a so-called quick draw, which is coupled in a releasable manner with the spit; the rope 34 can run inside the quick draw. Alternatively, and again purely by way of example, the anchoring point 36 may be formed of a "fast" connection, for example a friend, to whom the rope is appropriately coupled.

In general, the anchoring point 36 is connected to the rock face 32 and is substantially fixed with respect to the latter, or in any case subject to limited movements with respect to the rock face 32. Furthermore, the rope 34 is coupled with the anchoring point 36, not necessarily in such a manner that at least one point of the rope 34 is fixed with respect to the anchoring point 36. Below, however, it is assumed for the sake of simplicity that the rope 34 has a first end fixed to the anchoring point 36 and a second end fixed to the harness 6 of the mountaineer 30, this hypothesis being very common in the studies on the dynamics of mountain falls and relative effects on the human body and on the equipment .

In practice, the rope 34 has a length 1, understood as the length of the portion of rope extending between the above- mentioned first and second ends. Therefore, during the progression, the mountaineer 30 finds himself at the most at a distance equivalent to 1 from the anchoring point 36. Below it is assumed that this distance is measured along a vertical axis parallel to the direction of gravity and passing through the anchoring point 36, i.e. it is assumed that the mountaineer 30 is at point A, which is at a height equivalent to 1 with respect to the anchoring point 36, the rope 34 being completely taut between its first and second ends . It is further assumed that the distances cited are measured along the above-mentioned vertical axis and therefore equate to corresponding heights . This situation commonly occurs when the rock face 32 is substantially vertical .

In the event of a fall , it is assumed that the mountaineer 30 falls initially in free fall , as far as a point B, with respect to which the anchoring point 36 is at a height equivalent to 1. The point B therefore lies at a distance h from point A equivalent to 2*1. Subsequently, due to deformation of the rope 34 , the mountaineer 30 continues falling as far as a point C, below point B and lying at a distance from the latter equivalent to d . In practice , the fall stops at point C, where the mountaineer has null speed; furthermore , d represents the maximum deformation to which the rope 34 is subj ect .

In quantitative terms , it can be demonstrated that , thanks to conservation of the energy, and if the characteristic load- deformation of the rope 34 is linear, the follow relation holds : mg(h + d) = kd² 12 Ml in which k=E*A/l, where E is equal to the Young's modulus of the rope 34 and A is equal to the area of the section of the rope 34. Indicating by F the force to which the rope 34 is subject, and therefore also the harness 6 and the mountaineer 30, in general it is equal to k*x, where x is the deformation to which the rope 34 is subject. Since, when the mountaineer 30 is at point C, the deformation of the rope 34 assumes the maximum value, also the force F to which the rope 34 is subj ect is maximum and is equal to the product k*d. The following equation therefore holds:

^max² - ^2m§^F _mm - ^2m≠^{h = 0} ₍2) hence the maximum value F_raax of the force F to which the rope 34 is subject is equal to:

F_max ^mg[l ₊ ^\ + 2f_cEAI{mg)] ₍₃₎ in which f_c=h/l and is also known as the fall factor. It follows that the maximum acceleration to which the mountaineer 30 is subject, and therefore the maximum value a_max of the above-mentioned modulus of acceleration | a | , is equal to: a_maK=g[l + ^ + 2f_cEA/(mg)] ₍₄₎

In the case of the fall previously described, the above- mentioned modulus of acceleration signal M_A(t) has over time a trend of the type shown in figure 4.

Initially, at a time t₀ in which the mountaineer 30 is not yet falling but is at a standstill with respect to the rock face 32 , the modulus of acceleration signal M_A (t) is equal to a value g_r, which indicates that the modulus of acceleration I a I is equal to the acceleration of gravity g.

Assuming that at a subsequent time t-_ the mountaineer 30 loses his/her grip and begins to free-fall, the value of the modulus of acceleration signal M_A(t) decreases until it takes on, at a subsequent time t₂ , a value a₀__r, which corresponds to a null value of the modulus of acceleration I a I . The modulus of acceleration signal M_A (t) remains equal to the value a₀__r, until the mountaineer 30 arrives at the above- mentioned point B. Assuming that the mountaineer is at point B at a time t₃ , subsequent to this time t₃ the rope 34 begins to deform. Consequently, the modulus of acceleration signal M_A(t) increases until it assumes, at a subsequent time t₄, a maximum value a_maxjr, which indicates that the modulus of acceleration | a | assumes a corresponding maximum value a_max. In practice , in the time interval between the times t_x and t₃ , the mountaineer 30 is in free fall ; furthermore , at time t₄ the mountaineer is at point C and the fall has terminated .

After time t₄ , the mountaineer 30 is substantially subject to damped bouncing . Therefore , the modulus of acceleration signal M__A(t) decreases until it takes on the value a_{0 r} again, at a subsequent time t₅. Furthermore , the modulus of acceleration signal M_A(t) remains equal to the value a_{0 r} until a subsequent time t₆.

After the time t₆ , the modulus of acceleration signal M_A (t) increases until it takes on a first relative maximum value a_reii__jr at a subsequent time t₇. The first relative maximum value a_reii__r is lower than the maximum value a_{max r} and indicates that the modulus of acceleration | a | is equal to a corresponding first relative maximum value a_en , lower than the maximum value a_max. After the time t₇, the modulus of acceleration signal M_A (t) decreases to a time t₈, in which it takes on a first residual value ai_owi _r, higher than the value a₀___r and lower than the value g__r . Thereafter, the modulus of acceleration signal M_A ( t ) remains equal to the value a-_{lowl r} until a time t₉.

After time t₉ , the modulus of acceleration signal M_A (t) increases until it takes a second relative maximum value a_rei₂_ _r , at a subsequent time t_i0. The second relative maximum value a_rei_{2 r} is lower than the first relative maximum value a_reii_ r and indicates that the modulus of acceleration | a | is equal to a corresponding second relative maximum value a_rei₂ -

Lastly, after time t_i0, the modulus of acceleration signal M_A(t) decreases to a time t_u, in which it takes on a second residual value ai_ow2__r, the latter value being equal to the value g_r. In practice, at time tu, the mountaineer 30 finds himself, if no dissipative phenomena are considered, at point C, in which he subsequently remains, in the absence of further actions. The mountaineer 30 is now stationary with respect to the rock face 32.

Given the time trend of the modulus of acceleration signal M_A (t) , the first processing unit 10 can determine the corresponding values taken over time by the modulus of |a| which, within the interval between the times t_x and tu, has an absolute maximum, with value equal to the above-mentioned maximum value a_max. The first processing unit 10 determines the maximum value a_max of the modulus of acceleration | a | to which the first electronic unit 2 is su j ect . Furthermore , the first processing unit 10 determines the maximum value F_max of the force to which the rope 34 , the harness 6 and the mountaineer 30 are subject, multiplying the maximum value a_max of the modulus of acceleration |a| by the mass of the mountaineer 30.

Purely by way of example, the value of the mass m of the mountaineer 30 may be stored in the memory 14 , in a per se known way. For example , the value of the mass m can be set via the user interface 24 whi h, in a per se known way, allows a signal to be acquired indicative of the mass itself . Subsequently, the signal indicative of the mass is notified by the second processing unit 20 to the first processing unit 10 , which stores the value of the mass m in the memory 14.

In addition, for each event of fall , the first processing unit 10 increments by one unit a counter which is initially set to zero . The counter may be stored in the memory 1 .

In order to detect each event of fall , the first processing unit 10 detects the presence of an absolute maximum of the modulus of acceleration [a|, which has a value higher than the acceleration of gravity g and falls within a time interval between two successive periods of time in which the modulus of acceleration | a | is equal to the acceleration of gravity g . It should be noted that the above-mentioned maximum value a_max of the modulus of acceleration | a | is absolute only in the time interval between the two successive periods of time in which the modulus of acceleration | a | is equal to the acceleration of gravity g . If necessary, the first processing unit 10 can filter beforehand the modulus of acceleration signal M_A(t) and implement a comparison mechanism for comparing the maximum value a_max determined by it with a pre-defined acceleration threshold, and detect the event of fall only in the case of the acceleration threshold being exceeded. The counter is therefore incremented only if the acceleration threshold is exceeded .

In practice , the first processing unit 10 detects each event of fall and associates the corresponding ma imum value F_max of the force to which the rope 34 is subject, as determined by it. Furthermore , the first processing unit 10 stores in the memory 14 each event of fall and the maximum value F_max associated with the event of fall, which is also referred to as the maximum force F_max of the event of fall.

The first processing unit 10 also verifies, at each event of fall, if a critical wear threshold of the rope 34 has been exceeded, on the basis of the maximum force F_max relative to the event of fall, and on the basis of the maximum forces F_max relative to any preceding events of fall.

For this purpose, within the memory 14 a critical rope curve n_c (F_max) is stored, an example of which is shown in figure 5. The critical rope curve n_c(F_max) is stored in the memory 14; in particular, the critical rope curve n_c(F_max) is set via the user interface 24 and subsequently notified by the second processing unit 20 to the first processing unit 10, which stores it in the memory 14. The critical rope curve n_c(F_max) is of the discrete type , it is a function of the physical characteristics of the rope 34 and indicates, for a pre-defined number of reference values (shown in figure 5 on the x axis) , a corresponding maximum number of falls n_c . In particular, given a reference value, the corresponding maximum number of falls n_c indicates the maximum number of falls with maximum force F_max equal to this reference value which the rope 34 can withstand, before becoming dangerously worn. As shown in figure 6, in which the detection operations for detecting each event of fall are indicated by 90, at each fall the first processing unit 10 determines (block 100) the corresponding maximum force F_max, and subsequently determines (block 102) , on the basis of the critical rope curve n_c(F_max), the corresponding reference value which comes closest to the maximum force F_max determined. Subsequently, the first processing unit 10 determines (block 104), again on the basis of the critical rope curve n_c(F_max), the maximum number of falls n_c which corresponds to the reference value determined; subsequently it is assumed, for example, that this corresponding maximum number of falls n_c is equal to X.

The first processing unit 10 then increments (block 106 ) by a quantity equal to l/X a damage indicator, which is stored in the memory 14 and was originally initialised to zero.

Lastly the first processing unit 10 compares (block 108) the damage indicator with a rope safety threshold, equal to one for example.

If the damage indicator is below the rope safety threshold (NO output of block 108) , it means that the rope 34 can still be used safely. Therefore, the first processing unit 10 keeps the light indicator 16 off (block 110) .

Vice versa, if the damage indicator is above the rope safety threshold (YES output of block 108) , it means that the rope 34 has become critically worn. In this case, the first processing unit 10 operates (block 112 ) the light indicator 16, so as to signal to the mountaineer 30 that the wear on the rope 34 is such as to make further use thereof inadvisable .

As previously mentioned, although the preceding description explicitly refers to wear of the rope 34 , the first processing unit 10 can also detect, alterna ively or in addition to what has been explained above , critical wear of mountaineering equipment different from the rope 34 , for example the harness 6. For this purpose , in place of the critical rope curve n_c (F_raax) , a critical harness curve (not shown) is used, which is a function of the physical characteristics of the harness 6 and indicates, for each reference value, the corresponding maximum number of falls n_c which the harness 6 can withstand before becoming dangerously worn. For example, the critical harness curve may be obtained from the critical rope curve n_c(F_max), by adding to the latter a constant, not necessarily positive .

Similarly, it is also possible for the first processing unit 10 to detect, alternatively or in addition to what has been previously explained, critical wear of equipment such as a quick draw, for example, or an anchor, for example the anchoring point 36, via the use of corresponding critical curves . It is also possible for the first processing unit 10 to determine further quantities, for example the distance h between the point A and the point B (figure 3), on the basis of the equation h=l/2*g*t_c ², in which t_c is the duration of the time interval between the times ti and t₃.

In addition, the first processing unit 10 can determine one or more of the following quantities: an index of damage sustained by the body of the mountaineer, a quantity indicative of the energy used by the mountaineer during the progression, one or more quantities indicative of the evolution of the posture of the mountaineer during the progression, and one or more quantities indicative of the movements performed by the mountaineer. For this purpose, the first electronic unit 2 may comprise, as shown in figure 7, a gyroscope 40 and a localization module 42 , both connected to the first processing unit 10 and to the battery 12 (the latter connections not being shown) . The localization module 42 is for example of the Global Positioning System ^■- GPS - type . In this way, the first processing unit 10 can determine a path tracing signal , in terms of position and altimetry . As shown again in figure 7, the first electronic unit 2 may further comprise a transmitter 44 of the avalanche transceiver type , connected to the battery 12 and to the first processing unit 10. The transmitter 44 is of the type that can be activated by the mountaineer 30 or, preferably, by the first processing unit 10 , after detection by the latter of an event of fall , followed by a period of time of predefined duration, in which no movements of the mountaineer 30 occur . In this way, the transmitter 44 can be activated even when the mountaineer 30 is not conscious .

Although not shown, it is also possible for the first electronic unit 2 to comprise a magnetometer, which acts as a compass, and/or a pressure sensor, which acts as an altimeter.

According to a different embodiment, it is also possible for at least part of the operations performed by the first processing unit 10 to be performed by the second processing unit 10. In this case , it is possible for example for the measured acceleration electrical signal provided by the accelerometer 8 to be transmitted to the second processing unit 20 , which generates the modulus of acceleration signal M_A (t) and the subsequent processing . Analogously, also the signals coming from the gyroscope 40 and/or from the localization module 42 may be transmitted to the second processing unit 20 , if necessary after storage within the memory 14.

According to yet another embodiment , shown in figure 8 , the first electronic unit 2 may be integrated inside a mobile phone 50 of known type . For this purpose, since the mobile phone 50 has its own battery, its own processing unit, its own memory and a screen that can be used as a light indicator, it is possible to store in the memory of the mobile phone 50 a program which, whe run, allows the processing unit of the mobile phone 50 to perform the operations described previously, on the basis of the signals coming from the accelerometer and from any other sensors present in the mobile phone 50. In other words, the accelerometer 8 and the first processing unit 10 may form a mobile phone 50, i.e. be integrated inside the latter. Furthermore, the value of the mass of the mountaineer can be set by using the keypad of the mobile phone 50, in which case the second electronic unit 4 may be absent, likewise also the first communication stage 18.

The advantages offered by the present electronic device clearly emerge from the preceding description. In particular, it allows quantitative determination of critical wear on a fall protection device, such as to make continued use of the same inadvisable.

Lastly it is obvious that modifications and variations can be made to the present electronic device, without departing from the scope of the present invention, defined by the attached claims .

For example, the accelerometer may be of uniaxial type, in which case it should be constrained to the mountaineer so that its axis is parallel to the direction of the fall.

Embodiments are also possible in which the relation between the modulus of acceleration signal M_A(t) and the modulus of acceleration to which the accelerometer is subject is of different type from the one described.

As a substitute or alternative to the light indicator 16, an indicator of different type may be present, for example an acoustic indicator.

Lastly, although explicit reference has been made to mountaineering , the present electronic device can be used, for example, also in the context of acrobatic jobs or site work, i.e. in any field in which the personnel may be subject to falls .

Claims

1. An electronic device adapted to detect wear of a fall protection device, comprising a first electronic unit (2) which can be constrained to a user physically connected to said equipment , said first electronic unit including an accelerometer (8) adapted to generate an electrical acceleration signal (M_A(t) ) indicating an acceleration to which the first electronic unit is subj ect ; said electronic device further comprising a processing stage ( 10 ) con igured to detect , based on the electrical acceleration signal , events of fall of the first electronic unit , the processing stage being further configured to determine , for each event of fall , a corresponding value of maximum force (F_max) indicating the maximum force to which the first electronic unit is subj ect during the fall, based on the electrical acceleration signal; said processing stage being further configured to check, at each event of fall, whether a critical wear threshold of said fall protection device has been exceeded, based on the corresponding value of maximum force .

2. The electronic device according to claim 1, wherein the processing stage (10) is configured to update, at each fall , the value of a quantity indicating the wear of said fall protection device, based on the corresponding value of maximum force (F_raax) , and to compare the updated value of said quantity with a wear threshold value indicating said critical wear threshold.

3. The electronic device according to claim 2 , further comprising a memory (14 ) configured to store a critical curve (n_c (F_max) ) , which is a function of at least one physical characteristic of said fall protection device and correlates a number of reference force values with corresponding maximum numbers of falls ; and wherein the processing stage ( 10 ) is configured to update the value of said quantity also on the basis of said critical curve .

4. The electronic device according to claim 3 , wherein the processing stage ( 10 ) is configured to detect whether the critical wear threshold of a harness (6) worn by the user (30) , or of a rope (34) mechanically coupled to said harness, or of an anchoring point (36) to which the user (30) is connected, has been exceeded .

5. The electronic device according to any one of the preceding claims, wherein the processing stage ( 10 ) is configured to determine , for each event of fall detected, the maximum value (a_max) of the modulus of the acceleration to which the first electronic unit (2) is subj ect during the fall, said maximum force value (F_max) being a function of said maximum value of the acceleration modulus and of the mass of the user (30) .

6. The electronic device according to any one of the preceding claims, wherein the first electronic unit (2) includes the processing stage (10 ) , which is electrically connected to the accelerometer (8) .

7. The electronic device according to claim 6, further comprising means (24 ) for acquiring a signal indicating the mass of the user (30) , said acquisition means being couplable to the processing stage (10) .

8. The electronic device according to claim 7 , further comprising a second electronic unit (4) configured to communicate with the first electronic unit (2) and including said acquisition means (24 ) .

9. The electronic device according to any one of the preceding claims , wherein the first electronic uni (2) comprises an optical and/or acoustic signaling device (16) , the processing stage (10) being configured to activate said signaling device if said critical wear threshold of the fall protection device is exceeded .

10. The electronic device according to any one of the preceding claims , wherein said accelerometer (8) and said processing stage (10) form a mobile phone (50) .

11. A method for detecting the wear of a all protection device, comprising the steps of : generating (90) an electrical acceleration signal (M_A (t) ) indicating an acceleration to which a user (30), to whom said fall protection device is physically connected, is subj ect ;

- detecting (90) , based on the electrical acceleration signal, the user's events of fall;

determining (100) , for each event of fall, a corresponding value of maximum force (F_max) indicating the maximum force to which the user is subject during the fall, based on the electrical acceleration signal; and

checking (108) , at each event of fall, whether a critical wear threshold of said fall protection device has been exceeded, based on the corresponding value of maximum force .

12. The method according to claim 11, further comprising the steps of:

- updating (106) , at each fall, the value of a quantity indicating the wear of said fall protection device; and

- comparing (108) , at each fall, the updated value of said quantity with a wear threshold value indicating said critical wear threshold.

13. The method according to claim 12, further comprising the step of storing a critical curve (n_c (F_max) ) , which is a function of the physical characteristics of said fall protection device and correlates a number of reference force values with corresponding maximum numbers of falls; and wherein said updating step (106) comprises updating said value of said quantity also on the basis of said critical curve.

14. The method according to claim 13, further comprising the step of detecting whether the critical wear threshold of a harness (6) worn by the user (30), or of a rope (34) mechanically coupled to said harness, or of an anchoring point (36) to which the user (30) is connected, has been exceeded.