Method for detecting and calculating the duration of a jump

Abstract

The invention relates to a method for detecting and calculating the duration of a jump effected by an individual, comprising the following steps: Detection of a moment associated with a landing following the jump, this step comprising a sub-step of detecting an acceleration peak of an amplitude greater than a first threshold amplitude, within the acceleration measurements provided by a three-axis accelerometer, on board a watch worn on the wrist of the individual. Detection of a jump phase, by detection, in a temporal window finishing at the moment of landing, of a succession of acceleration measurements between 0 g and 0.5 g during a duration greater than a first threshold duration.

Claims

1. A method for detecting and calculating the duration of a jump effected by an individual, comprising the following steps: detection of a moment associated with a landing following the jump, this step comprising a sub-step of detecting an acceleration peak of an amplitude greater than a first threshold amplitude, within the acceleration measurements provided by a three-axis accelerometer, on board a watch worn on the wrist of the individual, detection of a jump phase, by detection, in a temporal window finishing at the moment of landing, of a succession of acceleration measurements between 0 g and 0.5 g during a duration greater than a first threshold duration, g being the acceleration due to gravity at the Earth's surface, detection of a moment associated with the start of the jump corresponding to the first measurement of the succession of acceleration measurements between 0 and 0.5 g, calculation of a duration of the jump by the difference of the moment associated with the landing and the moment associated with the start of the jump, the step of detecting a moment associated with a landing comprising a sub-step of detecting a pressure peak of an amplitude greater than a second threshold amplitude and of lesser duration than a second threshold duration, from pressure measurements provided by a pressure sensor on board the watch, and a sub-step of comparing the moment associated with the acceleration peak and the moment associated with the pressure peak.

2. The method according to claim 1, in which the second threshold amplitude is greater than 2 millibars and the second threshold duration is less than 0.1 second.

3. The method according to claim 1, in which the first threshold duration is greater than 0.5 second.

4. The method according to claim 1, in which the first threshold amplitude is greater than 2 g.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Other features and advantages will emerge clearly from the description which is given hereafter, by way of indication and in no way limiting, with reference to the annexed drawings, in which:

(2) FIG. 1 represents an electronic watch making is possible to implement the method according to one embodiment of the invention.

(3) FIG. 2 illustrates an example of the trajectory of a ski jump.

(4) FIG. 3 shows a curve representing acceleration measurements, superimposed on a curve representing pressure measurements, the measurements being produced during the jump of FIG. 2.

(5) FIG. 4 shows a functional diagram which is representative of the steps of the method.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(6) The method METH according to the invention is implemented integrally by an electronic watch MT worn by an individual making a jump. In a non-limiting embodiment shown in FIG. 1, the watch MT comprises: a set of sensors CP, comprising an accelerometer CP_AC and a pressure sensor CP_PR (or altimeter) a memory MD for recording measurements produced by the sensors CP. The measurements are advantageously recorded in the memory in a sliding manner, according to the FIFO principle (first in, first out) a microprocessor MP for processing the information contained in the memory MD digital or analogue display means MA for displaying the results of the calculations produced by the microprocessor MP activation means MC, mechanical, electronic or tactile, of the sensors CP, of the memory MD, of the microprocessor MP and of the display means MA, making it possible to trigger the method PR.

(7) FIG. 2 shows an example of the trajectory of a jump, occurring during a ski jump. In a first phase P.sub.1, the individual is in contact with the ground. At a time t.sub.0, the individual takes off from the ground, and in a second phase P.sub.2, the individual is in the rising phase. At a time t.sub.1, the individual reaches a maximum altitude H.sub.1 and, in a third phase P.sub.3, the individual is in a descending phase. At a time t.sub.2, the individual lands on the ground, and in a fourth phase P.sub.4, the individual is again in contact with the ground.

(8) FIG. 3 shows a curve C.sub.1 representing the altitude measurements AT calculated from the pressure measurements picked up by the pressure sensor CP_PR of the watch MT, as a function of the time t, and in particular during the four phases P.sub.1, P.sub.2, P.sub.3 and P.sub.4. A curve C.sub.2 representing the acceleration AC measured by the accelerometer CP_AC of the watch MT as a function of the time t, is superimposed on the altitude curve C.sub.1.

(9) A first step of the method METH according to the invention consists of detecting that a jump has been effected (step METH_Dr in FIG. 4). More particularly, the detection step METH_Dr comprises a first sub-step METH_Dr_PC.sub.AC consisting of detecting an acceleration peak PC.sub.AC in the measurements provided by the accelerometer CP_AC. In fact, when a jump is effected, an acceleration peak PC.sub.AC is observed at the moment t.sub.2, i.e. upon the individual landing on the ground. When such a peak PC.sub.AC is detected, it is compared to a threshold value beyond which it is decided that the peak PC.sub.AC corresponds in fact to a landing on the ground following a jump.

(10) In one embodiment, in order to confirm that this acceleration peak PC.sub.AC in fact corresponds to a landing following a jump, the detection step METH_Dr likewise comprises a second sub-step METH_Dr_PC.sub.PR consisting of detecting a pressure peak PC.sub.PR in the measurements provided by the pressure sensor CP_PR. The corresponding altitude peak PC.sub.AT is represented in FIG. 3. If a jump has in fact taken place, such a pressure peak PC.sub.PR should be picked up at a moment which is substantially identical to that at which the acceleration peak PC.sub.AC was detected. The moments corresponding to the pressure peak PC.sub.PR and to the acceleration peak PC.sub.AC are therefore compared. If the norm of the difference between these moments is less than a threshold value, for example 0.5 second, then it is decided that the peaks PC.sub.PR, PC.sub.AC correspond in fact to a landing on the ground following a jump.

(11) A second step of the method METH according to the invention consists of detecting a jump phase (step METH_Ds), by detection, in a temporal window finishing at the previously determined moment t.sub.2, of a succession of acceleration measurements AC between 0 g and 0.5 g during a duration greater than a first threshold duration t.sub.S. For this, the acceleration measurements AC in a temporal window preceding the acceleration peak P.sub.AC, for example a temporal window of about ten seconds, are analysed. More precisely, the step METH_Ds for detecting a jump phase comprises calculation of the norms of the acceleration measurements of the temporal window. It is therefore possible to determine if the acceleration peak PC.sub.AC is preceded by a succession of measurements between 0 g and 0.5 g during a duration greater than the first threshold duration t.sub.S. If this is the case, it is confirmed that a jump has in fact taken place and that the acceleration peak PC.sub.AC corresponds to a landing on the ground. In fact, during the third phase P.sub.3, the individual is in free fall and therefore undergoes an acceleration of approximatively 0 g. The first of the succession of measurements between 0 g and 0.5 g corresponds to a time t.sub.0 attributed to the start of the jump.

(12) In a third step of the method, the duration Ts of the jump is calculated (step METH_Ts). For this, the moment t.sub.2 associated with the landing is subtracted from the moment t.sub.0 associated with the start of the jump.

(13) It is noted therefore that the step METH_Ds for detecting a jump phase contributes not only to confirming that a jump has in fact taken place but likewise to calculating the duration of this jump.

(14) Of course, the present invention is not limited to the illustrated example but is applicable to different variants and modifications which will appear to the person skilled in the art.