WO2017139897A1

WO2017139897A1 - Ski pole with integrated sensors for force and power measurement

Info

Publication number: WO2017139897A1
Application number: PCT/CA2017/050209
Authority: WO
Inventors: Hans Christian FISCHER; Anton Hubert FISCHER; Alastair Smith
Original assignee: Proskida Inc.
Priority date: 2016-02-19
Filing date: 2017-02-17
Publication date: 2017-08-24
Also published as: EP3416559A4; EP3416559A1; CA3014959A1

Abstract

The present disclosure discloses a ski pole having a set of integrated sensors that support the calculation of force expended by a skier. The sensors include a computer processor embedded in the ski pole handle and a force sensor, connected to the processor, for sensing the axial force which is mounted on the ski. In order to calculate the force applied tangentially by the skier in the direction parallel to the surface over which the skier is moving, the angle that the pole section is at during applied force needs to be detected and this may be achieved with various sensors, one non-limiting example being IMU sensors integrated in the computer processor in the handle. In order to calculate the power output by the skier, there is included a sensor for determining speed (e.g. a GPS of a mobile device wirelessly connected to the ski pole sensors and hardware), and sensors suitable for determining the terrain slope. In one example embodiment, the terrain slope is determined by assuming a constant angle of the ski pole relative to the ground, and using the change in orientation of the ski pole to determine and map the corresponding change in terrain. The known speed, terrain slope, orientation of the ski pole relative to gravity, and axial pole force may be employed to compute time- dependent power.

Description

SKI POLE WITH INTEGRATED SENSORS FOR FORCE AND POWER

MEASUREMENT FIELD

The present disclosure relates to a ski pole with integrated sensors for power measurement.

BACKGROUND

There is significant variability in heart rate among athletes depending on training schedules, intensity and duration. It is not possible to rely on heart rate alone as a measure of performance and improvement. In the absence of a method to measure performance in the field, expensive stationary ergometers are used to measure power output. This is the case for cross country skiing and biathlon. The biomechanics of the sport are so complex, it has not lent itself to a method of measuring overall power output while in a natural training

environment forcing high level athletes to use heart rate as an inaccurate proxy. From a performance point of view, simply put, the higher the wattage an athlete can generate, the stronger and faster they are.

Currently, monitoring external training loads in Nordic skiing is limited to speed. This creates difficulties in monitoring training adaptations due to varying terrain conditions. Measuring power during skiing, similar to other sports, would aid in overcoming these limitations, and can lead to future research in training and performance analysis. Current methods of assessing power are laboratory based and too bulky to use in the field. Monitoring training in cross country skiing is primarily related to monitoring internal physiological loads from heart rates to lactate production. While this method allows a coach and athlete to understand how the body responds to the acute training bout, it does not provide any information on the external training output such as the speed they are moving at, thus limiting the ability to monitor performance adaptations. External training outputs, such as speed, can be used to help relate these internal physiology loads to enhanced performance. However, speed is a function of both the terrain and snow conditions in cross country skiing, making any analysis reflective of certain terrains and conditions. As a result using external training loads to monitor training adaptations in the field is very limited in the sport. Sports such as cycling, deal with the varying terrains by monitoring power as an external workload instead of speed. Attempts to analyze power development in cross country skiing is limited to the lab as equipment is bulky and not robust for field use. Therefore, having a compact power meter to measure muscular power output during skiing can aid in normalizing external workloads across different terrains, and help improve training programs for skiers.

Therefore it would be very advantageous from a training perspective to have a power meter configured for measuring upper body muscular power output during Nordic or cross country skiing and to give real-time information on their effective poling force, enabling them to better focus on improving performance. SUMMARY

Disclosed herein is a ski pole having a set of integrated sensors that support the calculation of force expended by a skier. The sensors include a computer processor embedded in the ski pole handle and a force sensor, connected to the processor, for sensing the axial force which is mounted on the ski. In order to calculate the force applied tangentially by the skier in the direction parallel to the surface over which the skier is moving, the angle that the pole section is at during applied force needs to be detected and this may be achieved with various sensors, one non-limiting example being IMU sensors integrated in the computer processor in the handle. In order to calculate the power output by the skier, there is included a sensor for determining speed (e.g. a GPS of a mobile device wirelessly connected to the ski pole sensors and hardware), and sensors suitable for determining the terrain slope. In one example embodiment, the terrain slope is determined by measuring changes in air pressure with high resolution barometer sensors The known speed, terrain slope, orientation of the ski pole relative to gravity, and axial pole force may be employed to compute time-dependent power.

Thus, the present disclosure provides a device for assisting a subject's movement with integrated sensors for real time force measurement, comprising:

a) an elongate pole shaft having a pole shaft axis and first and second ends, said first end having attached thereto a ground engaging tip;

b) a handle attached to said second end; c) a force sensor mechanically coupled to said second of said pole shaft and to said handle and configured to sense in real time axial forces applied to said handle, by the subject, which axial forces are transmitted down said pole shaft to said ground engaging tip; and

d) a computer processor mounted in said handle, said force sensor being electrically connected to said computer processor to receive force data from said force sensor, a sensor for sensing in real time an angle of said pole shaft axis with respect to a tangent of a surface on which the subject is moving, said sensor connected to said computer processor with said computer processor configured to receive pole shaft angle data, said computer processor being configured to temporally correlate the force data with said angle data, said computer processor including a storage device for storing the temporally correlated force data and angle data, said computer processor configured to calculate in real time a component of force applied by the subject in a direction of travel of the subject.

A further understanding of the functional and advantageous aspects of the invention can be realized by reference to the following detailed description.

BRIEF DESCRIPTION OF DRAWINGS

The following is a description of the ski pole with integrated sensors for measurement of muscular power output by skiers, reference being had to the accompanying drawings, in which: Figure 1 A shows a cross section of an embodiment of a ski pole having an axial force sensor incorporated therein which is a button type compression sensor;

Figure 1 B shows a cross section of another embodiment of a ski pole having an axial force sensor incorporated therein which is a threaded tension and compression type force sensor;

Figure 2 shows a disassembled view of another embodiment of a ski pole having an axial force sensor incorporated therein which is a threaded tension and compression type force sensor, where the sensor is shielded mechanically shielded from bending moments by the overlapping bushings.

Figure 3A shows a cross section of another embodiment of a ski pole having an axial force sensor incorporated therein which is a button type compression sensor, and axial force isolation is achieved with low modulus material which in this embodiment is an adhesive ;

Figure 3B shows a cross section of another embodiment of a ski pole having an axial force sensor incorporated therein which is a button type compression sensor, and axial force isolation is achieved with a pole end oversleeve attached to the pole shaft with reversible hot glue, the over-sleeve being secured with use of use of low modulus material which in this embodiment is an adhesive that fills the space between the over-sleeve and the exterior component of the handle.

Figure 3C shows a cross section of a preferred embodiment of a ski pole having an axial force sensor incorporated therein which is a button type compression sensor, and axial force isolation is achieved with a pole end over- sleeve attached to the pole shaft with reversible hot glue, the over-sleeve being secured into the handle with use of use of low modulus material which in this embodiment is a collar of elastomeric material that overlaps a part of the oversleeve, and is secured in place by way of an annular compression clamping mechanism such as a threaded collet;

Figure 4 is Flow Chart 1 showing the steps for calculating the power expended by the subject while skiing based on the force applied as a function of time by the user, the instantaneous angle of the terrain, and the skier velocity.

Figure 5 is Flow Chart 2 showing an example of non-limiting possible computational algorithm for device control and data processing and storage.

Figure 6 shows a visualization of a skier on uneven terrain and the orientation of the ski poles as the skier skis uphill.

DETAILED DESCRIPTION

Various embodiments and aspects of the disclosure will be described with reference to details discussed below. The following description and drawings are illustrative of the disclosure and are not to be construed as limiting the disclosure. Numerous specific details are described to provide a thorough understanding of various embodiments of the present disclosure. However, in certain instances, well-known or conventional details are not described in order to provide a concise discussion of embodiments of the present disclosure.

As used herein, the terms "comprises" and "comprising" are to be construed as being inclusive and open ended, and not exclusive. Specifically, when used in the specification and claims, the terms "comprises" and "comprising" and variations thereof mean the specified features, steps or components are included. These terms are not to be interpreted to exclude the presence of other features, steps or components.

As used herein, the term "exemplary" means "serving as an example, instance, or illustration," and should not be construed as preferred or advantageous over other configurations disclosed herein.

As used herein, the terms "about" and "approximately" are meant to cover variations that may exist in the upper and lower limits of the ranges of values, such as variations in properties, parameters, and dosage ranges to give a few examples.

Disclosed herein is a device for assisting a subject's movement with integrated sensors for real time force measurement. The device includes an elongate pole shaft having a pole shaft axis and first and second ends with the first end having attached thereto a ground engaging tip. A handle attached to the second end and a force sensor is mechanically coupled to the second of the pole shaft and to the handle and it is configured to sense in real time axial forces applied to the handle, by the subject, which axial forces are transmitted down the pole shaft to the ground engaging tip when in use. The device may be a walking stick, ski pole or a paddle to give a few non-limiting examples.

The device includes a computer processor mounted in the handle and the force sensor is electrically connected to the computer processor in order to be able to receive force data real time from the force sensor. The device includes a sensor for sensing in real time an angle of the pole shaft axis with respect to a tangent of the ground or surface on which the subject is moving. The sensor is connected to the computer processor with the computer processor configured and programmed to receive pole shaft angle data real time, and computer processor is programmed and configured to temporally correlate the force data with pole shaft angle data such that at each instant that a force is applied to the pole by the subject, the angle of the pole is also known at that instant. The computer processor includes a storage device for storing the temporally correlated force data and pole shaft angle data and the computer processor programmed with instructions to calculate in real time a component of force applied by the subject in the direction of travel of the subject over the surface.

The temporal correlation referred to above refers to the correlation of the described force and angle measurements at each datum collected, the angle measured being the angle of the pole relative to the tangent of the surface being traversed, in particular the tangent of the surface either in the location of the pole tip at the time of initiation of the individual pole stroke being

quantitatively characterized, or the location of the subject at the time of initiation of the pole stroke, or some calculated combination of the two to provide a representative surface tangent for the immediate vicinity of the subject at the time of the pole stroke, all of which require a determination of the terrain angle at the location of the of subject either at each temporal correlation point, or at those temporal correlated data corresponding to the initiation of a pole stroke. The present device will be further described with reference to Figures 1 A, 1 B, 2, 3A, 3B and 3C in which the followed numbered components are referenced.

Numbered components:

12 Ski pole shaft

14 Body of grip

16 Strap

18 Pole end insert

20 Pole bushing

22 Grip bushing

24 Mechanical stop feature in grip

26 Button type force sensor

28 Force sensor connecting wire

30 Battery

32 Computer processor (nomenclature?)

34 LED

36 USB port

Threaded type tension/compression force

38 sensor

40 Jam nut

42 Threaded insert

44 Elastomer washer

46 Rotational constraint protrusion

Receiving gap for rotational constraint

48 protrusion

50 Strap jam wedge

52 Electronics cover

54 Handle padding

56 Pole end over-sleeve

58 Low modulus material, or adhesive

60 Elastic rotation and tensile constraint

62 Annular compression clamp

64 Over-sleeve bushing

Figures 1 A and 1 B illustrate two possible embodiments of the integration of an axial force sensor and angle sensor into a ski pole shown generally at 10 and 66 respectively. In pole 10 in Figure 1 A, the force sensor 26 is a button type compression sensor. In pole 10 in Figure 1 B the force sensor 26 is a threaded tension and compression type force sensor 38. In the embodiment shown in Figure 1 A, propulsive forces are applied to the elongate shaft 12 of the ski pole 10 by the skier via gripping the handle 14, and exerting force on the ground where the distal end of the shaft 12 (not shown) contacts the surface on which the subject is propelling themselves. The compressive loads on the pole 10 are transmitted solely to the button of the compression force sensor 26, located at the central axis of the pole shaft 12, by a pole end insert 18, that bridges and closes the open hollow end of the pole shaft 12 thereby allowing poling forces to be transmitted to the force sensor 26. The force sensor 26 is constrained at its proximal side by a mechanical stop feature 24 in the handle such that the button force sensor 26 transmits and quantifies all axial applied force.

Figure 1 A shows a cross section of an embodiment of a ski pole having an axial force sensor incorporated therein which is a button type compression sensor, this compression sensor being a preferred embodiment. In order to ensure that the axial force applied to the ski pole is isolated and can be quantified, in Figure 1 A a toleranced low friction material bushing system is used in which a pole bushing 20 is secured to the handle end of the bare elongate section pole 12, and a corresponding handle bushing 22 is secured within the handle 14. When assembled, the pole bushing 20 will slide freely in the axial direction of the ski pole, within the handle bushing 22 thereby isolating the axial forces. The gap/fit tolerances between the pole bushing 20 and the handle bushing 22 dictate how much angular displacement the ski pole tip can undergo without movement of the pole handle 14.

Tensile and rotational loads between the handle 14 and the pole 12 are resisted by a small area of elastic, low modulus mechanical coupling between the pole 12 and the handle 14. In this possible embodiment, it is a flexible annular connection 60 that is adhered at one end to the outer surface of the pole, and adhered at the other end to the handle, thereby preventing the pole 12 from sliding out of the handle 14, and ensuring that the pole and pole tip/basket at the distal end of the ski pole retains its preferred rotational alignment relative to the handle 14.

Referring to the embodiment of the pole 60 shown in Figure 1 B, propulsive forces are applied to the ski pole 60 by the skier via gripping the handle 14, and exerting force on the ground where the distal end of the elongate pole section 12 contacts the surface on which the subject is propelling themselves. The compressive loads on the ski pole 60 are transmitted solely through the axial shaft of the threaded tension and compression sensor 38 located at the central axis of the ski pole, which is essentially the same axis as the central longitudinal axis of pole shaft 12. In this embodiment, the threaded tension and compression sensor 38 joins two portions of the handle 14 that are otherwise independent pieces separated by a thin high modulus elastomer washer 44 the purpose of which is to provide bending stiffness to the handle across the join between the independent pieces. The distal portion of the handle 14 contains has the ski pole adhered within it and has a threaded insert 42 to provide a robust attachment of the threaded tension and compression force sensor 38 to the distal portion of the handle 14 and attached pole 12. The tension and compression sensor 38 is constrained at its proximal side by a mechanical stop feature 24 (identical in function as stop feature 24 in Figure 1 A) in the handle 14 such that the tension and compression sensor 38

transmits and quantifies all axial applied force.

To ensure that the axial force applied to the ski pole 60 is isolated and can be quantified, the sole attachment of the upper portion of the handle 14 where force is applied, and lower portions containing the elongate pole section 12, is the threaded tension and compression force sensor 38 itself, which provides the pole use performance needs of retaining the pole shaft 12 in the handle 14 and the jam nuts 40 enable setting the rotational position of the sensor 38 to ensure that the pole 60 and pole tip/basket (not shown) at the distal end of the pole section 12 retains its preferred rotational alignment relative to the handle 14.

In the embodiments in both Figures 1 A and 1 B, detected force data from either the button type force sensor 26 or threaded tension and

compression force sensor 38 is transmitted via connecting wire 28 and collected by computer processor 32 which includes wireless communication to separate devices. The computer processor 32 and force sensors 26 and 38 are powered by the battery 30. A USB port 36 facilitates battery charging and wired communication to the computer processor 32. An multicolored LED 34 indicates various states and is capable of providing feedback on e.g. battery charge, comparison of force data relative to a desired threshold. Figure 2 shows another embodiment of a ski pole 70 wherein force exerted by the skier into the pole handle 14 which has a padding layer 54 via the strap 16 is transmitted to the ground by the pole shaft 12 to achieve propulsion. The strap 16 is secured by the strap jam wedge 50. The

compressive loads on the pole 70 are constrained to axial loads into the force sensor by concentric cylindrical bushings, with bushing 20 mounted on the pole shaft 20 and the bushing 22 being attached to the interior of the handle 14. The distal end of the force sensor 38 is threaded into a pole end insert 18 that bridges and closes the open hollow end of the pole section 12 thereby allowing poling forces to be transmitted to the force sensor 38. The force sensor 38 is constrained at its proximal side by transverse mechanical stop feature 24 in the handle 14 such that the threaded axial compression and tension force sensor 38 transmits and quantifies all axial applied force, and through which the second threaded end and force sensor connecting wire 28 protrude and are there secured with a jam nut 40 on the top of pole section 12. In this embodiment the force sensor 38 is a threaded axial compression and tension force sensor (for example, one commercially available model is LIGENT LFT- 13C).

Force sensor 38 in Figure 1 B and Figure 2 are similar but sensor 38 has both ends threaded so that it provides the ability for sensor 38 to tensionally link the pole section 12 and the handle 14 whereas the button cell 26 of Figure 1 A cannot.

To ensure that the axial force applied to the ski pole is isolated a toleranced low friction material bushing system is used in which pole bushing 20 is secured to the handle end of the bare pole, and the corresponding handle bushing 22 is secured within the handle 14. When assembled, the pole bushing 20 will slide freely in the axial direction of the pole section 12, within the handle bushing 22 thereby isolating the axial forces. The gap/fit tolerances between the pole bushing 20 and the handle bushing 22 dictate how much angular displacement the ski pole tip can undergo without movement of the pole handle 14. The sole attachment of the handle 14 where force is applied, and distal portions containing the upper or proximal end of pole section 12, is the threaded tension and compression force sensor 38 itself, secured by the two jam nuts 40 as can be seen in Figure 2, which provides the tensile strength required for pole use performance (retaining the pole section 12 in the handle 14) The rotational position of the pole section 12 and pole tip/basket at the distal end of the pole section 12 is retained in its preferred rotational alignment relative to the handle by a rotational constraint protrusion 46 on the pole bushing 20, and a corresponding receiving gap for the rotational constraint protrusion 48 in the handle bushing 22.

Detected force data from the threaded tension and compression force sensor 38 is transmitted via connecting wire 28 and collected by computer processor 32 which includes wireless communication to separate devices. As with poles 10 and 60, the computer processor 32 and force sensor 26 are powered by the battery 30. A USB port 36 facilitates battery charging and wired communication to the computer processor 32. A multicolored LED 34 indicates various states and is capable of providing feedback on e.g. battery charge, comparison of force data relative to a desired threshold. The electronics are protected from contact by the skiers hands by the electronics cover 52.

Figure 3A shows a cross section of another embodiment of a ski pole 80 having an axial force sensor incorporated therein which is a button type compression sensor, and axial force isolation is achieved with low modulus material which in this embodiment is an adhesive. In ski pole 80, propulsive force is applied by the skier in to the handle 14 via the strap 16 which is secured by the strap jam wedge 50, the force then being transmitted via the pole 12 to the ground. The compressive loads are transmitted through and detected by compressive force sensor 26 placed such that it's centre axis is parallel to the pole axis, ensuring it is incapable of measuring any applied force other than axial compression. The transmission of compressive loads through the force sensor is achieved in the case of a miniature sensor of smaller diameter than the pole shaft 12 diameter by supporting the distal side of the force sensor by a pole end insert 18 (that bridges and closes the open hollow end of the pole 12 thereby allowing poling forces to be transmitted to the force sensor 26. The force sensor 26 is constrained at its proximal side by a transverse mechanical stop feature 24 in the handle such that the button force sensor 26 transmits and quantifies all axial applied force. In this embodiment the pole 12 and pole end insert 18 are secured directly in the handle with a low modulus adhesive 58 such that tension and torsion forces applied are prevented from noticeably moving the pole 12 relative to the handle 14 by the adhesive join 58, but axial forces are transmitted to the button load cell. Figure 3B shows a cross section of another embodiment of a ski pole shown generally at 90, having an axial force sensor incorporated therein which is a button type compression sensor, and axial force isolation is achieved with a pole end over-sleeve attached to the pole shaft with reversible hot glue, the over-sleeve being secured with use of use of low modulus material which in this embodiment is an adhesive that fills the space between the over-sleeve and the exterior component of the handle. More particularly, in ski pole 90, the pole shaft 12 is secured within a pole end over-sleeve 56 with reversible hot glue, the over-sleeve 56 being secured with low modulus material 58 in the handle 14. The low modulus material 58 in this embodiment being a low modulus adhesive.

Figure 3B is similar to Figure 3A, but differs in that the pole shaft 12 is secured into the dead-end sleeve 56 with standard pole/handle attachment techniques (hot glue) and the sleeve 56 is previously integrated and adhered in the handle 14 with low modulus adhesive 58.

FIGURE 3C shows a cross section of a preferred embodiment of a ski pole shown generally at 90, having an axial force sensor incorporated therein which is a button type compression sensor 26, and axial force isolation is achieved with a pole end over-sleeve 56 attached to the pole shaft 12 with reversible hot glue, the over-sleeve being secured into the handle with use of use of low modulus material 58 which in this embodiment is a collar of elastomeric material that overlaps a part of the over-sleeve, and is secured in place by way of an annular compression clamping mechanism 62 such as a threaded collet. Lateral constraint of the over-sleeve 56 within the handle 14 is provided by a over-sleeve bushing 64.

Figure 3C is similar to Figure 3B, but differs in that the handle 14 is secured onto the dead-end sleeve 56 with an annular clamp 62 that

compresses a region of low modulus material between the handle 14 and the over-sleeve 56.

It will be appreciated that the configurations of the force sensor integrated into the ski poles in Figures 1 A, 1 B, 2, 3A, 3B and 3C are exemplary and non-limiting. For example force sensors may be integrated onto the exterior of the ski pole are located away from the handle, so long as they are configured to measure axial forces.

The above disclosure relates to the ski pole configured to give real time forces with respect to time applied by the subject skier, which requires the presence of the force sensors 26 or 38.

In order to calculate the force applied tangentially by the skier in the direction parallel to the surface over which the skier is moving, the angle that the pole section 12 is at during applied force needs to be detected and this may be achieved with IMU sensors integrated in the computer processor 32 in the handle. An absolute horizontal ertical reference frame detected by the IMU sensing the direction in which gravity acts provides the comparison for all other angle readings. An angle orientation calibration upon turning on the computer processor may be necessary.

Central to the detection of force and angle, subsequent calculations, and communication of the resultant data are the electronics capable of performing these tasks. The computer processor 32 identified in the figures represents a generic placeholder for all onboard electronics, The actual components integrated into the computer processor 32 include a) an inertial measurement unit (IMU) consisting of digital chip based mutually orthogonal accelerometers, magnetometers, and gyroscopes, and typically a digital pressure sensor for the function of altimeter, b) wireless communication capability such as Bluetooth, ANT+ or Bluetooth low energy (BLE), c) amplification circuitry for the purpose of conditioning the input signal from the force sensor, d) control electronics able to coordinate the collection, correlation, and communication of various data streams, e) USB connection 36 (or any other comparable type of connection system) for physical connection and battery charging, f) connection to the battery 30. Additional non-essential components include, but are not limited to: LED indicator for status of power state, charge, charge level, magnitude of applied force; speaker for auditory feedback.

An IMU refers to inertial measurement unit, typically consists of but is not limited to an integrated combination of three gyroscopes, three

magnetometers, and three accelerometers wherein each set of three (3) like sensors are oriented mutually orthogonally. Various data filtering techniques (for example sensor fusion algorithms) are used to condition and improve the accuracy and dependability of the output data. Alternatively, altitude and heading reference system (AHRS) developed initially for use in aircraft provides similar data typically without the integrated magnetometers. Additionally, pressure sensors can be integrated into either unit providing data redundancy and opportunity for correction. It will be appreciated that all angle measurements (both for the pole and any other angle measurements from which the slope of tangent to the surface are calculated) are made by calculating the relative rotational position of the sensor relative to a gravitational reference. From initial measurements, determining the angle of the pole relative to the tangent of the surface uses basic trigonometry/geometry.

Once the real time component of force applied by the subject in the direction of travel has been calculated, and this has been correlated with the real time angle data of ski pole section 12, this information can then be used to calculate the power output by the subject on the pole. In order to accomplish this the velocity of the subject over the ground or surface is required. To this end, a means for measuring velocity is required for calculating a velocity of the subject over the surface, and using this data along with the real time component of the force applied in the direction of travel the power output can be calculated, since power is equal to force x velocity. The means for measuring velocity may include measuring the change with respect to time of measured position, via using triangulation from known reference locations, either land based (cellular network towers, other radio beacons) or satellite based (GPS) to determine incremental positions of the subject.

In another embodiment, a direct measurement of velocity may be accomplished by detecting a Doppler shift in reference signals (i.e., by using GPS).

The velocity sensor may be incorporated into the handle, or alternatively it could be worn by the subject. If incorporated into handle, it may be connected to the computer processor such that the velocity data is transferred directly to the computer processor in which case the computer processor is programmed to do the power calculation. Alternatively the velocity sensor may have its own microprocessor forming part of the sensor and again it is connected to the computer processor which can then transfer the real time component of the force applied in the direction of travel directly to the microprocessor in the velocity sensor which in which case this microprocessor is programmed to do the power calculation. Another option is a third device that is a dedicated GPS device, like GPS watch or Catapult™ (a 10Hz gps used in realtime positioning) that provides velocity data in real time to the computer processor to do the power calculation, or provides the position and velocity data as a collected file after a recorded session is complete at which time the computer processor calculates power for the course covered during the session.

Similarly, if the velocity sensor is worn by the user, it may be hardwired to the computer processor in the handle, for example by a UBS port, or more preferred configuration is that the handle and velocity sensor are configured with a wireless communication system (e.g. Bluetooth™) that allows for wireless transmission, in either direction as discussed above, depending on which processor is programmed to do the calculation.

In an embodiment, a GPS unit may be used from which the velocity information can be obtained. For example, satellite signals can be used in different ways to determine a number of different measured parameters of movement and position. To measure the longitude, latitude and height, the GPS receivers measure the different delays in the signals coming from four (4) or more satellites. The distance to each satellite is calculated and then using triangulation, the 3D position of the GPS antenna is calculated. The determined longitude, latitude and height can be used to plot the path of the GPS antenna, and combining the elapsed time in between positions can provide speed and direction.

Alternatively, the satellite signals can be used to calculate the Doppler shift in the carrier frequency of each satellite transmission to build an accurate measurement of the speed of the GPS antenna in the X, and Y planes. The X and Y velocities are combined to give 'course over ground' speed and heading data.

This GPS unit may be integrated into the handle or it may be the GPS unit integrated into the subjects cell phone, or be mounted on the wrist or body of the user. Cell phones have Bluetooth™ wireless capabilities so these would be ideal as they can be in the pocket of the subject while they are skiing or walking. The real time power output of the subject may be displayed in a graphical form on for example the cell phone screen or a small display built into the handle of the pole. In addition, the power output may be stored and accessed at a later time. If the power calculation is performed by the processor contained in the handle it may be transferred to a computer via a USB port, or if it is to be transferred to a cell phone for display it may be via the wireless connection.

The sensor for sensing in real time an angle of the pole shaft axis (which is essentially the ski pole axis) with respect to a tangent of the surface or ground over which the subject is moving may be an inertial measurement unit (IMU). Five (5) non-limiting configurations or methods may be used for obtaining the tangent measurements and it is contemplated that more than one of the following may be used in combination.

1) Dead reckoning of external IMU (i.e., cell phone)

In this embodiment the double integral of accelerometer data from the IMU in the smart phone may be used to provide a translated distance in horizontal and vertical directions of the cell phone. Studies reported in scientific literature as well as existing products implement dead-reckoning techniques by basic integration from accelerations and detected movement of integrated sensor suites, a process which is susceptible to noise, and detection and accuracy limits of sensors. Techniques for mitigation of noise and resulting in improvements in accuracy include various types of Kalman filtering, Zero Velocity Update (ZUPT) and Zero Angular Rate Update (ZARU) Magnetic Angular Rate Update (MARU).

The change in position from one time stamped sample (coinciding with an identifiable feature within the signal of a pole plant) to the next may be used provide the distance traveled and the change in elevation, therefore also providing the slope. In this configuration the IMU (cell phone) needs to remain at a constant position on the subject, for example in a particular pocket.

2. Dead reckoning of IMU in pole handles

Same concept as 1. above, but the pole height would need to be used as an input to the calculations as the change in height of the IMU may not accurately reflect the change of height of terrain if the pole is planted at a different angle. Illustrated in Figure 6, using the known angle at the time of planting the pole, and the known length of the pole, a rotation about the point of contact of the pole tip with the snow can provide a calculated position of the handle that is a consistent stand-off height from the snow. Changes in that calculated position, based on second integral of IMU accelerometer data from one time stamped sample (coinciding with an identifiable feature within the signal of a pole plant) to the next would provide the distance traveled and the change in elevation, therefore also providing the slope.

3. Barometer Based Altimeter

Independent measurement of altitude can be performed with established and available technology (e.g., Bosch BMP085 temperature and pressure sensor chip, or BMP280 high precision capable of resolving 0.2Pa which approximately correlates to a detection of ~15cm change in elevation). Another non-limiting example chip that may be used is the BMP 380. Either the computer processor 32 in the handle or ancillary device will have a barometer integrated into it. Once zeroed and calibrated to account for weather changes, relative measurements can provide elevation and change in elevation and when combined with GPS based position in the horizontal plane data may be used to provide terrain slope.

4. GPS Location Based Cross Reference To Known Elevation From

Topographical Map Data

Known changes in X-Y position of the GPS unit combined with look-up elevation data, either in near-real time or after a session is complete, can provide (a coarse) indication of terrain slope, the accuracy of which is dependent on the resolution of the available topographical data and the accuracy of the collected GPS position data. A non limiting example chip would be the Inventek ISM420R1 .

5. Ski mounted IMU with signal communication to data processing

Direct measurement of the angle of one or both skis by using an inclinometer or sensor suite (IMU - non limiting example chip would be

InvenSense MPU9250) which provides the angle of the ground at the moment of sampling, assuming contact with the ground, relative to a gravity based reference frame.

Figure 4, "Flow Chart 1 " outlines a sequence of data collection and processing, explained in order of need for performing the power calculations, and represented by the numbers annotated on the flowchart

Step 1. Measure pole angle

The angle that the pole is at is detected. This is achieved with the IMU sensors integrated in the computer processor in the handle. An absolute

horizontal ertical reference frame detected by the IMU sensing the direction in which gravity acts provides the comparison for all other angle readings. An angle orientation calibration upon turning on the computer processor may be necessary.

Step 2. Measure Pole force

As described in Figures 1-3 describing any force sensor integration into the handle, any applied axial force is detected by the mechanically coupled force sensor and the value recorded within the computer processor within the handle. Step 3. Determine Terrain Angle For the purpose of explanation, we use here the example of #4 "GPS location based cross reference to known elevation from topographical map data" to determine the terrain angle.

Step 4. GPS

Using a technique for location detection, (e.g., GPS) the skier's 3D position is recorded by the computer processor.

Step 5. Determine vector of travel

Combining the known slope from Step 3. above, and fusing the GPS data from Step 4. Above and horizontal and vertical displacement of each of the pole handles a 3D vector of direction of travel of the skiers centre of mass can be calculated.

Step 6. Calculate effective pole force

Taking the applied pole force from Step 2. projected onto a combination of the terrain angle from Step 3. and vector of travel from Step 5., provides the amount of force resulting in displacement of the skier in the overall direction of travel.

Step 7. Skier velocity

Change in known position determined in Step 4. over time provides velocity of the skier. Step 8. Calculate pole power

Power exerted by the skier using their poles is calculated using effective pole force calculated in Step 6., and the skier velocity calculated in Step 7. The total upper body power contribution is a summation, or extrapolation (depending on the accuracy of data available) of the power generated from each ski pole. Referring to Figure 5, Flow Chart 2 describes the basic interaction of the user or subject with the electronics, namely initiating the program for data collection which turns on the sensors. The process of data collection and calculation is then initiated by a check whether a pole cycle has started based on the presence of applied force or patterns of characteristic movement, and if so, force and angle data is collected. The pole cycle is deemed complete when the magnitude of applied force returns to zero or whatever constant non zero value was determined to be the offset associated with force measurement with no axial load applied. Using the left pole for the purpose of explanation, the collected data is then used as input for the calculations described in Figure 4 "Flow Chart 1 ". Next, pole cycle data (frequency, timing) is stored, as is the calculated values of effective force (projection of applied force parallel with direction of travel vector) and ineffective force (any force component not parallel with the direction of skier travel). The force data collection is performed concurrently for the right pole. Force and derivative power data, calculated as described in Figure 4 is then stored.

Claims

THEREFORE WHAT IS CLAIMED IS:

1 . A device for assisting a subject's movement with integrated sensors for real time force measurement, comprising:

b) a handle attached to said second end;

c) a force sensor mechanically coupled to said second of said pole shaft and to said handle and configured to sense in real time axial forces applied to said handle, by the subject, which axial forces are transmitted down said pole shaft to said ground engaging tip; and

2. The device according to claim 1 , further comprising means for calculating a velocity of the subject over the surface, and including a

microprocessor programmed with instructions to calculate, from said velocity and said component of force applied by the subject in a direction of travel of the subject, power output by the subject.

3. The device according to claim 2, wherein said microprocessor is the computer processor mounted in said handle, and wherein said means for calculating a velocity of the subject over the surface is in communication with said computer processor for transmitting velocity data from said means for calculating a velocity to said computer processor.

4. The device according to claim 2 wherein said means for calculating said velocity uses a global positioning system (GPS) integrated into said handle, and wherein said microprocessor forms part of said GPS unit and which is connected to said computer processor and configured to receive said calculated real time component force, said microprocessor being programmed with said instructions to calculate said power output by the subject.

5. The device according to claim 2 wherein said means for calculating said velocity uses a global positioning system (GPS) integrated into said handle, said GPS unit being connected to said computer processor and configured to transmit said velocity to said computer processor, said computer processor being programmed with said instructions to calculate said power output by the subject.

6. The device according to claim 2 wherein said means for sensing velocity uses a global positioning system (GPS) unit worn by the subject during movement, and wherein said handle includes a wireless communication system for transmitting said calculated real time component force to said GPS unit, said microprocessor forming part of said GPS unit, and said microprocessor being programmed with said instructions to calculate said power output by the subject.

7. The device according to claim 2 wherein said means for sensing velocity uses a global positioning system (GPS) unit worn by the subject during movement, and wherein said handle includes a wireless communication system for receiving said real time velocity data from said GPS unit, said computer processor being programmed with said instructions to calculate said power output by the subject.

8. The device according to claim 6 wherein said GPS unit is integrated into a subject's cell phone, and wherein said cell phone is programmed to display in real time said power output by the subject.

9. The device according to claim 7 wherein said computer processor is connected to a visual display located on the handle and is programmed to display in real time said power output by the subject.

10. The device according to any one of claims 1 to 9 wherein said sensor for sensing in real time an angle of said pole shaft axis with respect to a tangent of a surface is an inertial measurement unit (IMU).

1 1 . The device according to claim 1 wherein said second end of said elongate pole shaft includes a threaded plug secured inside said second end, and wherein said handle and said pole include concentric cylindrical bushings having an interlocking feature to preserve rotational alignment between said handle and pole concentric bushings, and wherein said force sensor is a threaded axial compression and tension force sensor, one end of which is threaded into said threaded plug, and wherein said force sensor is a threaded axial compression and tension force sensor, one end of which is threaded into said threaded plug, and a second end and signal wire protruding through a hole in a transverse feature in the pole handle.

12. The device according to claim 1 1 wherein said force sensor is a compression force sensor, positioned such that it's centre axis is parallel to a pole axis such that the compressive loads are detected by the button load cell to ensure it is incapable of measuring any applied force other than axial compression, with one surface of the button force sensor supported by a transverse feature within the pole handle and an opposing surface of the sensor subjected to axial forces from the ski pole shaft, and wherein tension and rotation loads between the handle and the pole shaft are taken by a low modulus mechanical coupling between the pole shaft and the handle.

13. The device according to claim 12 wherein a low modulus mechanical coupling of pole end and handle interior extends throughout an overlap region between the pole end and handle, and wherein the handle and pole shaft are secured together such that tension and torsion forces applied by the subject are prevented from moving the pole relative to the handle by an adhesive joint between the handle and pole shaft, but axial forces are transmitted to the button load cell.

14. The device according to claim 12 wherein a low modulus mechanical coupling of pole end and handle interior extends throughout an overlap region between the pole end and handle, and wherein the handle and pole shaft are secured together such that tension and torsion forces applied by the subject are prevented from moving the pole relative to the handle, and wherein the upper end of the pole shaft is secured within a cylindrical lining sleeve with reversible hot glue, the lining sleeve being secured with low modulus adhesive in the handle interior.

15. The device according to claim 12 wherein a low modulus mechanical coupling of pole end and handle interior extends throughout an overlap region between the pole end and handle, and wherein the handle and pole shaft are secured together such that tension and torsion forces applied by the subject are prevented from moving the pole relative to the handle, and wherein the upper end of the pole shaft is secured within a cylindrical lining sleeve with reversible hot glue, the lining sleeve being secured in place by way of an annular compression clamping mechanism which compresses said low modulus mechanical coupling.

16. A method for measuring real time force output by a skier, comprising: a) detecting, using a force sensor integrated into a ski pole, axial forces applied by a subject to the ski pole as the skier skies over the ground, which axial forces are transmitted from a ski pole handle down a pole shaft to said ground engaging tip, storing the force data in a computer processor memory storage device;

b) sensing in real time an angle of said pole shaft axis with respect to a tangent of a surface on which the subject is moving to give angle data, storing the force data in the computer processor memory storage device, and temporally correlating, using the computer processor, the force data with the angle data, and storing the temporally correlated force data and angle data in the computer processor memory storage device; and calculating in real time, using the computer processor a component of force applied by the subject in a direction of travel of the subject, and storing the calculate component of force applied by the subject in the direction of travel of the subject.

17. The method according to claim 16, further comprising sensing a velocity of the subject over the surface, and including calculating, from said velocity and said component of force applied by the subject in a direction of travel of the subject, power output by the subject.