EP1623743A1

EP1623743A1 - Swim stroke monitor

Info

Publication number: EP1623743A1
Application number: EP05254561A
Authority: EP
Inventors: Kelvin Kwok Hang Leung; Shu Nam Chan
Original assignee: Jetfly Tech Ltd
Current assignee: Jetfly Tech Ltd
Priority date: 2004-08-03
Filing date: 2005-07-26
Publication date: 2006-02-08
Also published as: HK1064864A2

Abstract

A swim stroke monitor and a process for analysing a swimmer's swim strokes which uses a pressure sensor and analyses the pressure signal to determine the number of strokes.

Description

BACKGROUND

1. Field of the Invention

The present invention relates to technologies for measuring and analyzing quantitative information regarding a swimmer's swim stroke.

2. Background of the Invention

Swimming has long been recognized as one of the most demanding and competitive sports. Over the years, a variety of swimming aids have been developed and used by swimmers during training as part of an aquatic training program. Such aids have been designed to increase swim stroke efficiency and improve stroke technique and power.
For example, US Patent 5,663,897, assigned to Strokz Digital Sports, Inc. and entitled "Method and Apparatus for Analyzing a Swimmer's Swim Stroke," discloses a stroke monitor, which basically uses a metallic contact and a flexible membrane to achieve the stroke counting. Specifically, during swimming; water force is exerted on the flexible membrane so as to touch the metallic contact and thereby cause a processor to count the number of strokes.
Disadvantages exist with the design of the '897 patent. For example, the metallic contact of the '897 patent may be accidentally triggered due to the change of water force though a stroke may have not happened. Furthermore, the '897 patent does not teach detection of split information, which can also be of importance to the training of a swimmer.

OBJECT OF THE INVENTION

Therefore, it is an object of the present invention to provide a more accurate method and apparatus for analyzing a swimmer's swim strokes, or at least provide the public with a useful choice.

SUMMARY OF THE INVENTION

According to an aspect of present invention, firstly, a pressure sensor is used to collect a plurality of pressure information with respect to an environment surrounding the sensor. Afterwards, the collected information is analyzed to determine the number of strokes within a period of time.
Preferably, there can be an output for outputting at least part of the analysis result by the processor.
Other aspects and advantages of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which description illustrates by way of example the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Figures 1A and 1B illustrates positioning of a sensor in a watch-type stroke monitor according to an exemplary embodiment of the present invention;
Figure 2 is a block diagram of the monitor of Figure 1;
Figure 3 is a flow chart illustrating a process for analyzing strokes, which can be used in the monitor of Figure 1; and
Figure 4 illustrates a waveform of the signals useful in the monitor of Figure 1.

DETAILED DESCRIPTION

As shown in Figures 1A and 1B, a watch-type stroke monitor 100 according to an exemplary embodiment of the present invention generally has an enclosure 101 with a display 103 on its top 105 and a belt 107 attached to two ends 109, 111 of the enclosure 101 for attaching to a wrist (not shown) of a swimmer (not shown). A pressure sensor 113 is mounted in the enclosure 101 and silicon gel is coated on top of the pressure sensor for water resistance of the sensor in the exemplary embodiment. Therefore, when it is powered-up, the pressure sensor 113 is capable of continuously measuring the surrounding water and/or air pressures exerted thereon, which pressures are generally referred as environment pressures in the following description. Sensor of model number SM5106, available from Silicon Microstructures Incorporated, is an example of such pressure sensor and can be used in the exemplary embodiment of the present invention.
A pair of apertures 115,117 is created on a side 119 of the enclosure 101 to allow air or water to flow inside the enclosure 101 therethrough such that the pressure sensor 113 becomes in contact with the air or water so as to measure the environment pressures. Furthermore, in the exemplary embodiment, the pressure sensor 113 is placed at the rear of the watch, that is, the pressure sensor 113 is closer to a bottom 121 of the enclosure 101 as compared to its position relative to the top 105; the bottom 121 is a surface opposite to the top 105 and is generally in contact with the wrist of the swimmer when the monitor is in use. Such placement of the pressure sensor 113 is to reduce the impact of undesired light and mechanical shocks produced by arm movements.
In Figure 2, the pressure sensor 113 continuously measures the environment pressures, which generally refer to the air and water pressures in the exemplary embodiment, and further outputs the collected pressure information to a processor 201 connected thereto. The processor includes an analog-to-digital converter (not shown) for converting the analog signals from the pressure sensor 113 into digital signals for further processing. The processor 201 and other necessary electrical circuits are embedded in a waterproof part (not shown) inside the enclosure 101. The processor 201 analyzes the pressure information collected by the pressure sensor 113 and further displays the analysis results on the display 103. In the exemplary embodiment, the processor 201 is electrically connected to the pressure sensor 113 as well as the display 103. In addition, the monitor 100 may include various hardware components, for example function buttons, memory, battery, timer and so on, as generally understood in the art and disclosed in US Patent 5,663,897, which is herein enclosed by reference.
Referring to Figures 3 and 4, the process for analyzing the swimmer's strokes starts with step 301 "start," in which the swimmer may activate the monitor 103 by pressing a button (not shown) on the enclosure 101. At this moment, the pressure sensor 113 starts measuring the environment pressures.
Then in step 303, the swimmer selects a swim mode, for example, a breaststroke or a non-breaststroke, by pressing another button (not shown) on the enclosure. Upon such selection, the processor 201 selects an appropriate filter 305, 307 for subsequent processing, which will be further discussed. It is understood that the selection button can be configured to be the same as the start button as generally understood in the art.
In step 309, the processor 201 determines whether the swimmer has jumped into the water by detecting the occurrence of a sudden change 401 in the environment pressure. In the exemplary embodiment, before the swimmer jumps into the water, the swimmer stands outside the water, and the pressure sensed by the pressure sensor represents the air pressure and remains substantially stable as illustrate in Figure 4. When the swimmer jumps into the water, the water pressure is also exerted on the sensor and therefore there experiences a sudden change in the environment pressure sensed by the pressure sensor. Upon detection of this sudden change in the environment pressure, the processor 201 enters into the stroke measurement process, and a timer (not shown) is also triggered to record the lap time. In addition, if within a predetermined period, the sensor does not sense any sudden changes in the environment pressure, the processor 201 may terminate the process.
During the stroke measurement, the processor 201 firstly filters the collected pressure information to reduce environment noises by averaging a certain number of consecutive raw data. Furthermore, for different swim mode, different filters are used. For example, for non-breaststroke, filter X_filt(i)=(x(i)+x(i+1)+x(i+2)+ x(i+3)+x(i+4)+x(i+5))/6 is used, where x(i) is the raw data and X_filt(i) is the filtered signal. For breaststroke, filter X_filt(i)=(x(i)+2*x(i+1)+2*x(i+2)+ x(i+3))/6 can be used.
In the training sequence of step 311, the stroke monitor ascertains the first six consecutive maxima 403, 405, 407and minima 404, 406, 408 of the waveform. The maxima and minima are selected if the magnitude difference between the adjacent maximum and minimum, for example, 403 and 404, exceeds a predetermined value.
Then in step 313, the processor calculates some constants based on the information obtained during the training sequence, for example, the time interval and magnitude difference between adjacent maximum and minimum.
In step 315, the processor checks coming signal and counts the number of strokes by counting the number of the maxima of the waveform. In addition, the processor keeps checking whether a split happens or not in step 317. If there is no split yet, the process goes back to step 315. If a split happens, the processor calculates the lap time and the number of the strokes during this period. Then the processor resets the split as the start point and the process goes back to step 311 for a new round. The whole process may end when the swimmer stops swimming such that the processor detects no changes of the environment pressures over a certain period. The process may also end when the swimmer presses a stop button (not shown) on the enclosure. In step 317, the processor uses the information obtained in Step 313 for determining the occurrence of the split. Specifically, the processor may use the magnitude information to determine whether there is a split 409 in that normally a split causes a dramatic change in the environment pressure. Alternatively, the processor may use the time information for such purpose in that a split normally takes more time than a stroke.
Alternatives can be made to the exemplary embodiment. For example, different filters can be used. In addition, in Step 313; the processor may further calculates some magnitude threshold information for purpose of ascertaining the strokes or the split. Furthermore, the monitor may transmit the analysis results to other devices for display and/or further processing via, for example, wireless transmission.

Claims

A process for analyzing a swimmer's swim strokes, comprising:
providing a pressure sensor for detecting an environment pressure with respect to an environment surrounding the sensor;

collecting a plurality of environment pressure information; and

analyzing the collected information to determine the number of strokes, the analysis being dependent upon a variance in the environment pressure that the pressure sensor experiences.
The process of Claim 1, wherein the analyzing step includes determining a first pressure threshold information; and
comparing the collected pressure information with the first pressure threshold information to determine the number of strokes.
The process of Claim 2, wherein the analyzing step includes
determining a stroke if one of the collected pressure information exceeds the first pressure threshold information.
The process of Claim 1, wherein the analyzing step includes
counting a number of peaks among the plurality of collected pressure information,
wherein the number of peaks corresponds to the number of the strokes.
The process of any one of the preceding claims, further comprising
filtering the collected pressure information for reducing environment noise.
The process of Claim 5, further comprising
determining a swimming mode; and
selecting a filter for the filtering purpose, dependent upon the swimming mode.
The process of any one of the preceding claims, comprising
detecting a sudden change of the environment pressure after a period during which the environment pressure is at least substantially constant,
wherein the sudden change triggers the start of counting the number of strokes.
The process of any one of the preceding claims, comprising determining a second pressure threshold information; and
determining a split if one of the collected pressure information is below the second pressure threshold information.
The process of any one of the preceding claims, comprising
determining a plurality of time information with respect to time intervals between adjacent peaks of the plurality of collected pressure information.
The process of Claim 9, comprising
determining a split if one of the time information exceeds a time threshold value.
The process of Claim 10, wherein determining the time threshold value includes
selecting a predetermined number of time information; and
determining the time threshold value by averaging the predetermined number of time information.
The process of any one of the preceding claims, further comprising a training step, in which at least one constant is determined for assisting determination of the number of strokes.
A stroke monitor for analyzing a swimmer's swim strokes, comprising:
a pressure sensor for collecting a plurality of environment pressure information with respect to an environment surrounding the sensor;

a processor for analyzing the collected information to determine the number of strokes, the analysis being dependent upon a variance in the environment pressure that the pressure sensor experiences; and

an output for outputting at least part of the analysis result by the processor.
The stroke monitor of Claim 13, wherein the processor executes the following steps for analyzing the collected information:
determining a first pressure threshold information; and

comparing the collected pressure information with the first pressure threshold information to determine the number of strokes.
The stroke monitor of Claim 13 or 14, comprising an enclosure having a top, a bottom and at least a side, with an opening created on the side, wherein the pressure sensor is placed inside the enclosure and is in contact with water or air flowing inside the enclosure through the opening.
The stroke monitor of Claim 15, wherein the pressure sensor is placed in close proximity to the bottom as compared to its position relative to the top.