FIELD OF INVENTION:

The invention relates a pedometer and more specifically a pedometer with no user depended calibration.

BACKGROUND OF INVENTION:

Pedometer is a useful instrument as it can count number of steps, measure walking speed and distance traveled [1]. Most of the existing pedometers are based on Ultrasonic or piezo-electric sensors or a multi sensor approach to measure the above mentioned parameters [2-7]. A pedometer based on a 3-axis digital accelerometer has been reported [8-9]. It needs sophisticated algorithms to detect number of steps with good accuracy. A system has been reported in [10-11] for estimation of foot motion using inertial and magnetic measurements.

. Doc 1 : W.S. Shiou, W.H. Yi, "The Design of an Intelligent Pedometer Using Android,"/n Proc. 2nd Intr. conf. of IEEE IBICA, 16-18th Dec. 2011, pp. 313 - 315.

Doc 2 : Shinji Miyazaki, "Long-Term Unrestrained Measurement of Stride Length and Walking Velocity Utilizing a Piezoelectric Gyroscope," IEEE Transactions on Biomedical Engineering, vol. 44, no. 8, pp.753-759, August 1997.

Doc 3 : S. W. Lee and K. Mase, "Activity and location recognition using wearable sensors," IEEE Pervasive Comput, vol. 1, no. 3, pp. 24-32, Jul.-Sep. 2002.

Doc 4 : H. M. Schepers, H. F. Koopman, P. H. Veltink, "Ambulatory assessment of ankle and foot dynamics," IEEE Transactions on Biomedical Engineering, vol. 54, no. 5, pp. 895-902, 2007.

Doc 5 : Y. Jang, S. Shin, J. W. Lee and S. Kim, " A Preliminary Study for Portable Walking Distance Measurement System Using Ultrasonic Sensor," in Proc. 29th annual conf. oflEEEEMBS, 23-26* Aug 2007, France, pp. 5719 - 5721.

1 Doc 6 : J.CAIvarez, R.C.Gonzalez, D.Alvarez, A.M.Lopez, J.R. Uria, "Multisensor Approach to walking Distance Estimation with Foot Inertial Sensing," in Proc. 29th annual conf. oflEEEEMBS, 23-26? Aug 2007, France, pp. 5290-5293.

Doc 7 : D. Yanagisawa, A. Tomoeda, A. Kimura and K. Nishinari, "Designing Method for Large Queueing System by Walking- Distance introduced Queueing Theory," SICE annual conf, 20-22"d Aug 2008, Japan, pp. 1778 - 1783.

Doc 8 : Carlijn V. C. Bouten, Karel T. M. Koekkoek, Maarten Verduin, Rens Kodde, and Jan D. Janssen, "A Triaxial Accelerometer and Portable Data Processing Unit for the Assessment of Daily Physical Activity," IEEE Biomed. Eng., vol. 44, no. 3, pp. 136-147, .April 1997.

Doc 9 : Neil Zhao, "Full-Featured pedometer Design Realized with 3-Axis Digital Accelerometer," Analog dialogue 44-06, June 2010.

Doc 10 : X. Yun, J. Calusdian, E. R. Bachmann, and R. B. McGhee, "Estimation of Human Foot Motion During Normal Walking using Inertial and Magnetic Sensor Measurements," IEEE Trans. Instrum. Meas., vol. 61, no. 7, pp. 2059 - 2072, July 2012.

Doc 11 : A. M. Sabatini, C. Martelloni, S. Scapellato, F. Cavallo, "Assessment of walking features from foot»inertial sensing," IEEE Transactions on Biomedical Engineering, vol. 52, no. 3, pp. 486-94, March 2005.

Doc 12 - 4649552: An electronic pedometer for use on a footwear is disclosed. The pedometer comprises a step sensor carried by the footwear for sensing each step that the user takes to provide an output indicative thereof. Connected to the sensor is a mount base which is secured to the footwear and has thereon a first terminal electrically connected to the step sensor. A counter, which is detachably mounted on the mount base, has therein various electronic components forming a computing circuit and includes a display section. The counter is provided with a second terminal which comes .into electrical connection with the first terminal on the mount base when mounted -thereon so that the computing circuit receives the outputs from the sensor to compute based thereupon the number of steps taken and the distance travelled by the user. The resulting measurements of the computing circuit are visually indicated on the display section of the counter. Thus, the counter including the electronic components can be alone detached from the footwear while the mount base thereof and the sensor remain attached thereto, eliminating the troublesome procedure to remove the base mount secured to the footwear when the footwear is required to be washed as protecting the electronic components of the counter from being damaged during that washing. Accordingly, the convenience of using the pedometer on the footwear is greatly enhanced, leading to a widespread use of the pedometer.

Doc 13 -6145389: A pedometer is disclosed that accurately calculates the length of the strides taken by a user when walking and running. The length of each stride is calculated using measurements of the acceleration of the wearer's foot during each stride. This acceleration is measured by an accelerometer attached either directly or indirectly to the wearer's foot. The calculation of the stride length is performed by a data processor which analyzes the accelerations of the foot as measured by the accelerometer. The acceleration values for each stride are identified, and these are • used in conjunction with a set of coefficients to calculate the length of each stride. These coefficients are determined for each user by means of a calibration process during which the pedometer measures the characteristics of the wearer's stride for a variety of different walking and running speeds. Since the length of each stride is calculated independently, the user can change walking and running speeds and gaits without affecting the accuracy of the distance calculation.

Doc 14 - 2010/0184563: Systems and methods for sensing and monitoring various athletic performance metrics, e.g., during the course of a game, a practice, a training session, training drills, and the like are described. These systems and methods can provide useful metrics for players and coaches relating to athletic performances in various sports, including various team sports.

Doc 15 - AU 2005225023: A shoe has a pedometer incorporated, for example, in the tongue. The pedometer may be housed in a hinged case that opens about a horizontal 'hinge to reveal the display of the pedometer to the user. In some embodiments one shoe in a pair has a pedometer in a hinged case and the other shoe has a Cc hinged case without a pedometer in it.

OBJECT OF INVENTION:

The main object of the invention is to design a pedometer which does not demand user depended calibration. The other object of the invention is to design a pedometer based on inductive proximity.

SUMMARY OF INVENTION:

In this invention, we propose a new, simple and less expensive pedometer based on • inductive proximity. According to the proposed scheme, two simple modules will be integrated in to the shoes. When people walk, out of two shoes, one of them needs to be fitted with a small rectangular magnetic/conductive object. This is one of the modules. Second module is in the other shoe which is a magnetic/inductive proximity sensor. Output from this sensor module is employed to obtain walking speed, number of steps and distance traveled. Details of sensing principle, measurement scheme, prototype unit and results are discussed in following sections.

DRAWINGS:

Fig 1 Simplified schematic of the pedometer

Fig 2.1 Electrical equivalent circuit of the Inductive detector

Fig 2.2 Electrical equivalent of the switching based circuit

Fig 3 Block diagram of measurement system employed for preliminary studies

Fig 4 Schematic for speed measurement

Fig 5 The experimental setup with the prototype developed

Fig 6 Test results obtained from the prototype system. The distance traveled in each step was 30 cm.

•Fig 7 Another set of test results obtained when the distance traveled in each step was

FIG 8 Output from the unit recorded when a person was walking with the prototype unit integrated into the shoes. .
 
Fig 9 (a) .Lustration of GMR based pedometer. A unit with Giant Magneto resistor (GMR) based ICs are attached to the right .eg shoe while a permanent Magnet is fitted on the .eft .eg shoe, (b) Shows a simplified top view of (a), (c) Shows the magnetic f.e.d of M in relation to the GMR IC. (d) Shows block diagram of the measurement unit

Fig 10 Shows the waveform obtained when the magnet was moved in the d.rect.on of GMR-1 (G,) to GMR-2 (G2). The output signal of Gi is indicated as Vp and that from G2 is marked as Vq. VT is a threshold voltage.

Fig 11 Shows the flow chart to measure t1t t1 and TXY. The velocity can be calculated using this information.

DESCRIPTION OF INVENTION:

Modules of the proposed pedometer are indicated in Fig.1. They are, (a) a magnetic Object (O) fitted in the Left Leg (LL) shoe and (b) a Detector (D) fitted in the Right Leg (RL) shoe. The detector has two sensing elements. The elements are kept at a known distance in the detector unit. 'D' detects 'O' at two points (positions), when a leg passes the other leg, while walking. Object 'O' can be a small permanent magnet and sensing elements can be two Hall Effect/Magneto-resistive based ICs. Or the object can be a small piece of conductive or magnetic material and two sensing elements can be formed using two coils (inductors) connected in series as in Fig. 2.1.

Consider that the inductors (L, and L2) are excited from an ac source vin. vin is a sum of two sine waves, i.e., it contains two frequency components. Each inductor is connected with a capacitor in parallel as shown in Fig. 2.1. Both the inductors can have same value of inductance while unequal values will be chosen for capacitors C1 and C2. Thus, the system will have two different parallel resonant frequencies U and f2. Current drawn .from the source will be minimum, during operation, as the system is in parallel resonance. A resistor R is connected in series with the inductor-capacitor network to ^measure the change in current, l0. This is indicated in Fig. 2.1. When a conductive or magnetic object comes close to the inductor (detector), there will be a change in inductance and hence shift in parallel resonance frequency. This will result a change in the current, \Q. Voltage across R can be suitably amplified and give to an ADC. The digitized output can then be read by a microcontroller and it can compute and display the speed and the distance travelled.

Fig. 2.2 is another circuit (another way of measuring) where each of the inductors Li and /_2 can be energized and corresponding output is measured individually by operating the corresponding switch. Switches ( Si & S2 ) are operated in such a way that only one of the inductors is excited at a time. Once a measurement is made from L1} the system will excite L2 and take a measurement. After performing on L2, the system will measure from Li again and this will continue in a cyclic manner at a very high rate. The switches are controlled using the digital output (D0) lines (2) of the Data Acquisition System (DAS) or Micro-controller. The input excitation required for the circuit is given through the analog output (Ao) channel of the DAS. Output voltage across CMI and Cm are acquired using the analog input channels An and A12 of the DAS.

Fig. 3 shows the block diagram of the measurement system. The input signal vin can be generated by summing two sine wave signals (one at frequency ft and other at fi) using a summing amplifier. The output voltage v0 is given (in the prototype unit) to a USB based data acquisition system (DAS) to digitize the signal. Filter-1 is a band-pass filter which passes output signal corresponding to fi. Similarly, filter-2 passes the signal at h-In the prototype system, a computer with LabVIEW filters and then processes the signal from the DAS and measures the speed and distance using a program developed. A computer is used for the implementation of the scheme and preliminary studies. This can be replaced by a microcontroller so that the unit will be small in size, less expensive and portable. In a Hall Effect/Magneto-resistive IC based detector system, the output from the ICs can be given to an ADC and then to a microcontroller to compute the parameters and display.

*~A. Measurement of speed and distance travelled In this subsection, the method employed for measurement of speed and other parameters are described with the help of Fig. 4. In Fig. 4 (a), LL indicates the left leg with a metallic object O and RL indicates the right leg with two small inductors Li and L2. Inductors L? and L2 are kept at a known distance d in the detector unit. Xn and Yn are output voltages (refer Fig. 2 and Fig. 4) corresponding to inductors Li and L2 respectively. Consider, at the moment, that left leg moved from position 1 to position 3 keeping right leg stationary as indicated in Fig. 4b. During this process, when the object crosses the detector, two pulses will be generated in the output. A pulse, (indicated using X^ occurs when inductor Li senses the object and then another pulse (Yi) occurs when L.2 senses the object. The dimensions of the object and detector can be selected in such a way that only one of the inductor senses the object at a time. Now, consider • that the left leg is at stationary and the right leg moved from position 1 to position 3 as indicated in Fig. 4c. In this movement, the object will be first seen in the sensing vicinity of inductor L2 and produce an output Y2. Then it enters vicinity of inductor L* and gives an output X2. A pictorial representation of the output for the above discussed cases is given in Fig. 4 d and e. In these figures, waveform with dotted curves indicates output due to proximity of object near inductor L2 and the continuous curve indicates output due to proximity of object near inductor L*.

If we consider Fig. 4d, the duration between ti and ti' is the time taken by the object to move the distance 'd', between the two inductors. Since we know value of 'd', speed at which right leg is moving, during this distance d, can be calculated. Similarly, the speed of left leg can be obtained using the time interval between t2 and t2'. When one of the legs is moving the other leg is at rest. Let the speed of left leg be vte and that of right leg be vmi then the average resultant speed vt of body is the average value of vie and vm multiplied by a constant k as given below. v4=*[(v„+vte)/2] (1) where k = 1/2 which is due to the fact that, in reality, one of the legs is at rest when we move the other leg. Thus, we get average speed of walking but not the distance traveled. In equation (1) it is assumed that the average speed of right leg is vm and that of left leg is vte. This will be a factor deciding the accuracy of the method. When people walk in a continuous manner as shown in Fig. 4f, the time taken by the person to move from position 2 to 4 is the difference between the time at which Xi and X3 occur. Once we know the velocity and time taken, distance traveled, S, can be easily calculated. The distance traveled in this step will be stored (say S = D1) in the program (in microcontroller/PC). This will be added to the distance that will be detected in the next step (i.e., S - D1 + D2) and this process will be continued (i.e., S = D1 + D2+ + Dn). Number of steps can also be calculated. It is equal to one half of\ the sum of total number of pulses observed in Xn and Yn.

EXPERIMENTAL SET-UP AND RESULTS

A prototype of the proposed pedometer has been developed. Two inductors were placed on the right leg shoe at a distance of 10cm and a metallic strip of 10cm * 4.5 cm was placed on the left leg shoe. A snap shot of the experimental setup is shown in the Fig. 5. A coil was wound over a cylindrical shaped ferrite core of diameter 0.8cm to form the inductor. The inductors were fitted on a commercially available shoe. A capacitor C1 = 33nF was connected in parallel to Li = 150uH and another capacitor C2 = 39nF was connected in parallel to L2 = 300uH. The parallel resonance frequencies were noted at . fi = 71 kHz and f2 = 46 kHz. The excitation to the circuit was given from an arbitrary function generator. Sine waves of frequencies r> and r"2 were individually generated, added and given to the arbitrary function generator. The output v0 was given to an analog input channel of a data acquisition system, NI-USB 6216. The acquired signal was separated in to Xn and Yn using filters in a virtual instrument developed. In a practical unit, two commercially available signal generator ICs can be used for generating the excitation and the acquisition of detector output and processing can be performed using a suitable microcontroller.

In order to test the prototype, the right leg was placed (stationary) first and moved the left leg front by 30cm. Once the left leg reached a stationary position, the right leg was moved by 30cm. This process was repeated for some duration and the waveforms observed in the detector output were recorded and given in Fig. 6. During this test, the gap between the shoes, when they cross, was less than 10 cm. In Fig. 6, the time period between ti and ti' gives the time taken by the object in the left leg to move the distance 'd'. From this, we get the vfe. Similarly, vm can be found using t2 and t2'. From the waveforms given, it can be seen that both the legs are moving approximately at the same speed. In the next movement, where the left leg is moved by additional 30 cm, we get a change in the output voltage from Li (at t3) and then from L2 (at t3'). By taking the

• difference (t3 - ti) and then multiplying it with the average speed Vb of body (given by (1)), distance traveled during this time can be obtained. Similarly, we can compute the distance travelled for the other time intervals and the total distance travelled can be measured. In Fig. 6, v,e-i and vie3 are the speed measured for the left leg and vm2 is the speed measured for the right leg. It was found that vie1 = VM = vm2 = 5km/hr. For an actual distance of 960cm, the measured distance travelled was 956 cm and hence the error in the measurement was 0.36%. The above experiment was repeated by moving the legs in steps of by 40cm instead 30 cm. Fig. 7 shows the waveforms obtained. The speed of movement was again same as previous test. In this case also the error in measurement was about 0.33%. We have recorded the output waveforms when a person was walking continuously for a short distance of about 800m. A part of the recorded wave form is shown in Fig. 8. Test was conducted for different speeds and distances. The system computed the parameters and measured the speed and distance traveled accurately. Earlier in this document, it was mentioned that a pedometer can be developed using a permanent magnet M, instead of magnetic object and Hall effect or Giant Magnetoresistance GMR ICs instead of inductors. A pictorial representation of such a unit is shown in Fig. 9. Two GMR ICs are kept at a distance of 'cf cm on one of the shoes and a magnet M is fitted on the other shoe as illustrated in Fig. 9(a). Fig. 9(b)

• shows a simplified top view. GMR-1 (GO and GMR-2 (G2) are placed at a distance of d = 10cm. The system will also work for other values of 'd'. The magnet can be a bar or button type magnet (M) with its north facing the G and G2. The magnet can also be placed as its south facing the G1 and G2. The magnetic field of M in relation to the GMR ICs is represented in Fig. 9 (c). The Measurement unit consists of an input excitation to GMR ICs given from a DC power supply, say 5V. Output from G1 and G2 are given to ^Instrumentation Amplifiers, as indicated in Fig. 9(d), and then to an ADC and Microcontroller (or Microcontroller which has an ADC). The output signal VP observed from Gi and that of Vq obtained from G2 and a threshold voltage VT are indicated in Fig. 10(a). These signals were obtained experimentally when the magnet was moved from Gi to G2. In Fig. 10(b), the important timings such as ti, ti\ tXi, tX2, tYi and tY2 are indicated. In Fig. 10, it can be noticed that the outputs increases as the magnet go closer to Gi or G2 and it reduces as M moves away from Gi or G2, but it becomes zero or very small in value when the magnet is exactly/directly in-front of Gi or G2. This condition (Vp0 or Vqo ) occurs when the direction of magnetic field from M (seen by Gi or G2) is 90 degree to the axis of sensitivity of the GMR IC. This is illustrated in Fig. 9(c).

The micro-controller (MC) is programmed as given in the flow chart in Fig. 11. Whenever the output signal Vp goes more than W , MC will look for the condition Vp0. The time at which Vp0 occurs is measured by detecting txi and tx2. Average value of txi and tx2 is taken as t-i. Once ti is measured, the MC will look for tYi and tY2 (using VT) and ti' is computed by taking their average. The difference between V and ti is taken as the time TXY, which is the time taken for the magnet (or shoe or leg) to move from Gi to G2. The speed of the moving leg can be calculated by taking the ratio of TXY and distance 'rf between Gi to G2. Same procedure can be applied for calculating speed of the other leg. Only difference will be that Vq will come greater than VT before Vp (with respect to time). Speed of the human (body) can be obtained by taking average value of these speeds of individual legs multiplied by k=0.5 as described in the earlier algorithm that uses change in inductance values. The system will measure t2, t2\ t3 and t3' in a similar fashion for the next steps of the person walking. And, the number of steps and distance traveled by the person (by walking) can be obtained as described earlier in the inductive proximity method, using the parameters ti, ti', t2, t2', t3, t3', etc. It is appropriate to install or fit the pedometers described above on the shoes but it will also work even if it is fitted on the bottom-half of the legs or ankle with suitable fixtures.

A simple portable pedometer is presented. This can be easily embedded into shoes .and measure the number of steps, speed and distance traveled while walking or 1-jogging. Compared to existing systems, the new system requires very less amount of calibration. A prototype has been built and tested. Test results are promising. The developed device will be useful for travelers to monitor various parameters while walking, jogging, running, etc. In the invention as described above the pedometer essentially comprises of: a signal generator disposed within a first shoe, a first object detecting signal sensor

• assembly disposed on a first portion of a second shoe, and a second object detecting signal sensor assembly disposed on a second portion of the said second shoe, said first and second signal sensors being spaced away by a fixed distance and generally extending longitudinally of said second shoe and said each sensor assembly including a sensor for sensing signals generated by the said signal generator and for generating corresponding electrical signals, and a controller having an input coupled to the said sensor for receiving the said corresponding electrical signals. In another aspect said first and second signal sensor assemblies and said signal generator are aligned within said first and second shoes and in facing relation wherein said first and second shoes are worn by a user. In this embodiment the units are

• embedded in the shoes that is within the shoes. In another aspect, said first and second signal sensor assemblies and said signal generator are aligned on said first and second shoes and in facing relation wherein said first and second shoes are worn by a user. In this embodiment the units are embedded on the shoes. In another aspect, said first and second signal sensor assemblies and said signal generator are aligned along the first and second legs of a user in facing relation wherein said first and second legs are the left and the right legs of the user and wherein the said signal sensor assemblies and said signal generator may be disposed on the knees or on the ankles of the user. In this embodiment the unit is tied on to the user body that is it can be strapped onto the knee or ankle of the walker as these are the mobile portions which can identify the walking motion of the user. In another aspect, said signal generator comprises permanent magnet and wherein said first and second sensor assemblies comprises a hall effect sensor assembly '-adapted for converting the magnetic field generated by said permanent magnet to corresponding electrical signals.

In another aspect, said signal generator comprises permanent magnet and wherein . said first and second sensor assemblies comprises a GMR sensor assembly adapted for converting the magnetic field generated by said permanent magnet to corresponding electrical signals. In another aspect, said signal generator comprises of a conductive or a magnetic material and said first and second sensor assembly formed with two coils (inductors) connected in series. In another aspect, wherein said signal generator comprises of a conductive or a magnetic material and said first and second sensor assembly formed with two coils (inductors) connected with a mutually operable switching arrangement between the said two coils. In this it is possible to measure them individually with the help of this switching circuit in this embodiment. In this case the loops are not connected in series. The switching arrangement is made in such a way that the deductor unit measure the change in output from one of the inductors at a time. The unit will measure from first inductor for a short duration and thereafter from the other inductor for another short duration. It will then switch over to measure from the first inductor again and repeat the cycle alternatively between the first and the second inductor. This process can be made to continue in a cyclical rapid rate so as to be sufficient enough to deduct the variation in output from the inductors when the person wearing the unit is walking or running. As described above, there are many other variations that are possible in terms of measurement and also in terms of disposing the units on the user or on any of the ' object that can be fitted onto the leg portion of the user.

The present invention provides convenient shoes with low cost but accurate pedometer fitted therein. The invention has been explained with few embodiments & illustrations. However various modifications can be employed without departing from the sport of the invention. It is such that the above specification should not be construed as limiting the invention which defined by the appending claims.

WE CLAIM:

1. A pedometer comprising:

a. a signal generator disposed within a first shoe,

b. a first object detecting signal sensor assembly disposed on a first portion of a second shoe,

c. a second object detecting signal sensor assembly disposed on a second portion of the said second shoe, said first and second signal sensors being spaced away by a fixed distance and generally extending longitudinally of said second shoe, and

d. said each sensor assembly including a sensor for sensing signals generated by the said signal generator and for generating corresponding electrical signals, and a controller having an input coupled to the said sensor for receiving the said corresponding electrical signals.

2. The pedometer as claimed in claim 1 wherein said first and second signal sensor assemblies and said signal generator are aligned within said first and second shoes and in facing relation wherein said first and second shoes are worn by a user.

3. The pedometer as claimed in claim 1 wherein said first and second signal sensor assemblies and said signal generator are aligned on said first and second shoes and in

• facing relation wherein said first and second shoes are worn by a user.

4. The pedometer as claimed in claim 1 wherein said first and second signal sensor assemblies and said signal generator are aligned along the first and second legs of a user in facing relation wherein said first and second legs are the left and the right legs of the user and wherein the said signal sensor assemblies and said signal generator may be disposed on the knees or on the ankles of the user.

5. The pedometer as claimed in claim 1 wherein said signal generator comprises permanent magnet and wherein said first and second sensor assemblies comprises a hall effect sensor assembly adapted for converting the magnetic field generated by said permanent magnet to corresponding electrical signals.

6. The pedometer as claimed in claim 1 wherein said signal generator comprises permanent magnet and wherein said first and second sensor assemblies comprises a GMR sensor assembly adapted for converting the magnetic field generated by said permanent magnet to corresponding electrical signals.

7. The pedometer as claimed in claim 1 wherein said signal generator comprises of a conductive or a magnetic material and said first and second sensor assembly formed

• with two coils (inductors) connected in series.

8. The pedometer as claimed in claim 1 wherein said signal generator comprises of a conductive or a magnetic material and said first and second sensor assembly formed with two coils (inductors) connected with a mutually operable switching arrangement between the said two coils.