Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
  • G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
  • G01S19/13—Receivers
  • G01S19/14—Receivers specially adapted for specific applications
  • G01S19/19—Sporting applications
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
  • B62J—CYCLE SADDLES OR SEATS; AUXILIARY DEVICES OR ACCESSORIES SPECIALLY ADAPTED TO CYCLES AND NOT OTHERWISE PROVIDED FOR, e.g. ARTICLE CARRIERS OR CYCLE PROTECTORS
  • B62J45/00—Electrical equipment arrangements specially adapted for use as accessories on cycles, not otherwise provided for
  • B62J45/20—Cycle computers as cycle accessories

Definitions

• the invention relates to a method and a device for determining the pedaling frequency of a cyclist from a GNSS signal (acronym for "Global Navigation Satellite System”). satellite positioning) radiofrequency.
• GNSS Global Navigation Satellite System
• the pedaling rate of a cyclist is a key parameter for the performance analysis.
• the power developed by a cyclist can be calculated by:
• P T w (Eq. 1)
• P the power, in Watts
• T the pair of forces exerted on the pedals, in Newtons-meters
• w the angular velocity of the pedals w is itself a measure, normally in rad / s, the cadence of pedaling.
• the pedaling rate is typically expressed in revolutions per minute ("rpm"), but this is not a requirement but rather a habit (which is not meant to limit the invention). In this case, the rate is
• the forces on the pedals can be measured by sensors (eg strain gauges, eg installed at trays, cranks, hubs or pedals) or estimated indirectly depending on the speed, the slope of the ground, the weight of the cyclist, etc.
• sensors eg strain gauges, eg installed at trays, cranks, hubs or pedals
• the pedaling rate is measured using sensors which must be arranged in or on the bicycle, eg an accelerometer integrated in one of the cranks or a cadence sensor comprising a magnet attached to a crank and a pulse donor, responsive to the magnet, attached to the frame.
• sensors which must be arranged in or on the bicycle, eg an accelerometer integrated in one of the cranks or a cadence sensor comprising a magnet attached to a crank and a pulse donor, responsive to the magnet, attached to the frame.
• An object of the present invention is to provide an alternative determination of the pedaling rate.
• the invention is based on the observation that, given the pedaling movement, in stable conditions of effort of the cyclist, wind and slope, the power developed by a cyclist takes (approximately) the form of a sinusoid whose frequency is twice the pedaling frequency.
• This cyclic variation in power has the effect of a small oscillation of the cyclist's speed whose amplitude (a few centimeters per second) can be observed through GNSS phase measurements which are of a more precise order of magnitude (a few millimeters) .
• a first aspect of the invention therefore relates to a method of determining the pedaling rate of a cyclist on a cycle, in which the pedaling rate is extracted from an oscillation of GNSS signal phase measurements performed. on the cycle using a GNSS receiver or an oscillation of measurements calculated on the basis of phase measurements.
• cycle means a vehicle with two or more wheels propelled by the muscular energy of the person or persons on the vehicle (the rider or cyclists), including using pedals or cranks.
• cycle can therefore designate a vehicle powered exclusively by muscular energy or an assisted pedal cycle.
• GNSS signal means a radionavigation signal emitted by the satellites of one or more satellite positioning systems (eg GPS, GALILEO, GLONASS, SBAS, etc.
• a GNSS signal comprises a radiofrequency carrier modulated by a waveform (called “spreading") containing a pseudo-random code.
• spreading a radiofrequency carrier modulated by a waveform
• pseudo-random code Because carrier modulation causes spectrum spread around the carrier frequency, GNSS signals are often referred to as “spread spectrum”.
• Each pseudo-random code constitutes an identifier of the signal and its transmitter.
• the pseudo-random codes allow them a Multiple Access to Code Distribution (CDMA).
• CDMA Multiple Access to Code Distribution
• GNSS signals also carry data (eg the navigation message) in the form of a binary sequence (at a significantly lower rate than the pseudo-random code) modulated in addition to the carrier.
• GNSS receiver refers to a radio frequency receiver capable of receiving and processing GNSS signals, eg, to determine its position, speed and time.
• a GNSS receiver is typically capable of performing code measurements and measurements of the carrier phase ("phase measurements"). The two measurements correspond to the apparent distance between the transmitter and the receiver. Phase measurements are much more accurate than code measurements, but they contain an ambiguity equal to an integer multiple (unknown) of the carrier wavelength. These ambiguities being difficult, if not impossible (on conventional receivers), to be solved consistently for all GNSS signals, most applications can not rely solely on phase measurements but need code measurements. This is not the case in the context of this invention, since it is not necessary to remove the ambiguities of the phase measurements.
• the measurements calculated on the basis of the phase measurements could comprise Doppler measurements, the speed of the GNSS receiver, the projection of the GNSS receiver speed on a horizontal plane, the GNSS receiver speed standard, the acceleration GNSS receiver, the projection of the GNSS receiver acceleration on a horizontal plane and / or the GNSS receiver acceleration standard. This list is not exhaustive.
• the measurements calculated on the basis of the raw phase measurements can be obtained using time differentiated phase measurements ("TDCP measurements" of the time-differenced carrier phase).
• TDCP measurements of the time-differenced carrier phase.
• D i nes (tj) the Doppler shift TDCP on signal i at time tj
• the method comprises carrying out inertial measurements using one or more accelerometers and / or one or more gyrometers.
• Accelerometers and / or gyrometers can be part of an inertial unit or operate individually.
• the pedaling rate could be extracted from an oscillation of the inertial measurements (taken individually) or a measurement calculated on the inertial measurements only, when the phase measurements of GNSS signals are temporarily unavailable (eg below a bridge, in a tunnel, etc.) or too noisy.
• the method according to the first aspect of the invention may comprise the realization of phase measurements of GNSS signals by the GNSS receiver. It should however be noted that the method could also operate remotely, on measurements that are performed by a GNSS receiver on the cycle and transmitted by a telecommunication link to the processor that executes the process. In this case, the pedaling rate could be retransmitted via the same or another telecommunication link in the other direction, or used remotely, eg for delayed performance calculations.
• the method according to the invention could be implemented on any mobile device comprising or being connected to a GNSS receiver, eg on a multifunction mobile (in English: “smartphone"), a connected watch (or watch intelligent, “smart watch”), a GNSS receiver, etc.
• Some mobile terminals incorporating a GNSS receiver are configured to operate in a static or adaptive "duty cycling” mode. If “duty cycling” is enabled, the GNSS receiver operates in a mode that alternates between activity and inactivity intervals, which in particular reduces the power consumption of the GNSS receiver and thus increases the power consumption of the GNSS receiver. autonomy of the mobile terminal.
• the disadvantage of the "duty cycling" mode is that it involves interruptions of the measurements.
• the method could include detecting whether the GNSS receiver is operating in a mode that alternates between activity and inactivity intervals ("duty cycling" mode) and, where appropriate, (a) activation. a mode in which the GNSS receiver remains permanently active or (b) the adaptation of the length of the activity and inactivity intervals according to the needs of the determination of the pedaling rate.
• the extraction of the cadence of the oscillation of the phase measurements or measurements calculated on the basis of the phase measurements comprises a frequency analysis in the range of 1 to 6 Hz, corresponding to a cadence. pedaling between 30 and 180 rpm.
• Frequency (spectral) analysis could be done using a Fourier transform (normal or fast) and a peak detection (s) in the indicated range.
• the frequency range can be fixed or be dynamically adapted according to the speed, position and / or geographical information concerning the position of the cyclist. This would reduce the search for cadence to a reduced range, including the most likely range under the circumstances.
• the plausibility of the pedaling rate determined could be achieved. This plausibility analysis will preferably take into account that jumps in the determined rate may occur if the cyclist changes gear ratio. This may, for example, be done using the known cycle speed ratios (plateaux and gears).
• a second aspect of the invention relates to a method of evaluating the performance of a cyclist which comprises calculating the performance on the basis of the cyclist's pedaling rate determined by the method according to the first aspect of the invention. invention.
• a third aspect of the invention relates to a computer program, eg mobile application or web application, comprising program code instructions for performing the steps of the method when the program is run on a computer.
• the program is recorded on a computer medium (eg a memory, a storage medium, etc.), and is preferably accessible to a processor to be loaded into the RAM of that for the execution of the program.
• a fourth aspect of the invention relates to a mobile terminal, such as, for example, a multifunction mobile, a GNSS receiver, a connected watch, configured (eg using a computer program). for the implementation of the method according to the first and / or second aspect of the invention.
• FIG. 1 a schematic view of a cycle equipped with a GNSS receiver to perform carrier phase measurements
• Fig. 2 a graph illustrating the oscillations of the speed of a cycle due to pedaling.
• Figure 2 illustrates the pedaling effect of a cyclist on his speed. It is observed that the speed as a function of time has the form of a sinusoid with an amplitude of a few cm / s. The illustrated case is based on a simulation based on the following parameters:
• the oscillations obtained correspond to a rolling situation on the flat in steady state. Gravity forces, air resistance, rolling resistance and friction force have been taken into account. It can be seen that the amplitude (peak-to-peak) is about 4 to 5 cm / s. For a rolling situation on a 5 ° slope with otherwise the same assumptions as above, the amplitude (peak to peak) would be about 14 cm / s.
• FIG. 1 schematically shows a cyclist 10 on his bicycle 12.
• the cyclist has mounted a mobile terminal 14 (eg a GNSS receiver or a multifunctional mobile) on the cycle (for example on the handlebars) by means of a fixation.
• the mobile terminal 14 comprises an integrated GNSS receiver, capable of receiving and processing the GNSS signals 16 which are broadcast by the satellites 18 of one or more GNSS constellations. It should be noted that it is not essential for the invention that the mobile terminal is attached to the cycle. Indeed, the cyclist could also wear the terminal on his body (eg attached to the arm) or in a pocket.
• the multifunction mobile 14 is equipped with a mobile application that has access to the raw measurements made by the GNSS receiver and which is configured to execute a method according to the invention, in particular to extract the oscillations of phase measurements that are due to pedaling.
• the Doppler shift D £ is due to the relative movement between the satellite i and the GNSS receiver (RX) and is given by the formula:
• ÎRX Î is the frequency of the carrier of the signal i in the receiver's reference frame, ⁇ tc, ⁇ the frequency of the carrier of the signal i in the reference frame of the satellite i which transmits it (equal to the nominal frequency / of the carrier after compensation for the effects of drift of satellite clock), c the speed of light, v t the speed of satellite i, v RX actuator speed, r £ i the position of the satellite, the position of r RX receiver, "" the dot product and "
• the velocity and position vectors are indicated with respect to a common reference frame, eg a terrestrial reference frame.
• the observed carrier frequency (and thus the observed Doppler shift) by the receiver includes a systematic error due to the drift of the receiver clock ⁇ h RX and noise e.
• ⁇ h RX the drift of the receiver clock
• e the drift of the satellite clock
• the speed v t and position r e of the satellites can be calculated by the receiver using the GNSS ephemerides diffused in the navigation message contained in the GNSS signals or made available to the users by another means (Internet, GNSS helpdesk, etc.)
• the GNSS receiver can calculate its position in a conventional manner, using the code measurements. The positioning accuracy thus obtained is sufficient in this context.
• the measurements D i rnes , velocities and positions of the satellites as well as the estimate of the position of the receiver are combined by means of the Eq. 4.
• the system of equations can be solved for RX by the least squares method, a Kalman filter, or any other suitable method.
• the receiver To determine the oscillations, the receiver records the indeterminate values for a certain time and performs a frequency analysis in the range of 1 to 6 Hz.
• a frequency analysis may include a Fourier transform and a peak detection.
• a Fourier transform instead of carrying out this analysis on the components of v RX in an individual way, it is possible to realize it on the norm of the velocity vector ⁇ v RX ⁇ , on the projection of v RX on a horizontal plane, on the projection of v RX on the ground plane, on the projection of v RX on the longitudinal axis of the cycle, etc.
• the frequency of the oscillations of the speed being twice the cadence of the pedaling the frequency found by the spectral analysis is divided by 2. If necessary, a conversion in revolutions / minute is realized.
• the Eqs. 4 and 5 show that velocity oscillations have a direct impact on the carrier phase measurements if the vector v RX is not orthogonal to d ..
• Another possibility to determine the pedaling rate is therefore to submit (all) the raw phase measurements to a spectral analysis. So Alternatively, the terminal could be configured to first determine which satellites are best positioned (in terms of RX at t ), taking into account its current position and speed, and then detect the characteristic peaks of pedaling. in the spectrum of gross phase measurements for these satellites.

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• Engineering & Computer Science (AREA)
• Radar, Positioning & Navigation (AREA)
• Remote Sensing (AREA)
• Mechanical Engineering (AREA)
• Computer Networks & Wireless Communication (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Position Fixing By Use Of Radio Waves (AREA)
• Force Measurement Appropriate To Specific Purposes (AREA)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

Country Status (3)

Family Cites Families (4)

• 2018
  • 2018-05-15 FR FR1854058A patent/FR3081228B1/fr active Active
• 2019
  • 2019-05-10 WO PCT/FR2019/051065 patent/WO2019220040A1/fr unknown
  • 2019-05-10 EP EP19732408.0A patent/EP3794378A1/de active Pending

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