EP-4735856-A1 - METHOD FOR DETERMINING AT LEAST ONE FRICTION PARAMETER OF A CYCLIST UNDER REAL CONDITIONS OF MOVEMENT, AND ASSOCIATED DEVICES

EP4735856A1EP 4735856 A1EP4735856 A1EP 4735856A1EP-4735856-A1

Abstract

The invention relates to a method for determining at least one friction parameter of a cyclist under real movement conditions, on a banking section of track or road, extending longitudinally from a start line (LD) to a finish line (LA) over a length (L), each of the start line (LD) and the finish line (LA) extending transversely across a width (l). The method, based on an equation derived from the principle of conservation of energy, comprises a step of measuring a first transverse position (P1) at which the cyclist crosses the start line (LD) and a second transverse position (P2) at which the cyclist crosses the finish line (LA), each of the first and second transverse positions (P1, P2) being determined across the width (l) with an accuracy of +/-5 cm. The invention also relates to devices for measuring a transverse position at which the cyclist crosses.

Inventors

SELLIER, Manuel
HUCHARD, MATHIEU

Assignees

Aeroscale

Dates

Publication Date: 20260506
Application Date: 20240626

Claims (15)

Method for determining at least one friction parameter of a cyclist in real travel conditions, on a section of track or road having a slope and extending longitudinally from a starting line (LD) to a finishing line (LA) over a length (L), each of the starting lines (LD) and finishing lines (LA) extending transversely over a width (l), the method being based on an equation derived from the principle of conservation of energy expressed as follows: ΔE c = -W res – mgH + E m with ΔE c the variation in kinetic energy, W res the energy lost by aerodynamic friction and by rolling on the section, m the mass of the cyclist-bicycle couple, g the acceleration of gravity, H the difference in height and E m the driving energy produced by the cyclist on the section, and being characterized in that : - it comprises a step of measuring a first transverse position (P1) of passage of the cyclist on the starting line (LD) and a second transverse position (P2) of passage of the cyclist on the finishing line (LA), each of the first and second transverse positions (P1, P2) being determined along the width (l) with an accuracy of +/-5cm, - the variation of kinetic energy (ΔE c ) and the difference in level (H) are calculated between two positions: the first transverse passage position (P1) and the second transverse passage position (P2).
Method for determining at least one friction parameter according to the preceding claim, in which the measuring step involves at least one membrane potentiometer arranged on the starting line (LD) and on the finishing line (LA), along the width (l).
Method for determining at least one friction parameter according to the preceding claim, in which the membrane potentiometer is held on a rigid strip, which is arranged on the starting line (LD) and on the finishing line (LA), along the width (l).
Method for determining at least one friction parameter according to claim 1, in which the measuring step involves at least one time-of-flight measurement sensor, opposite each of the departure (LD) and arrival (LA) lines.
Method for determining at least one friction parameter according to one of the preceding claims, in which each of the first (P1) and second (P2) transverse positions is determined over the width (l) with a precision of +/-4cm, or even +/-3cm, +/-2cm, or even +/-1cm.
Method for determining at least one friction parameter according to one of the four preceding claims, in which the -at least one- membrane potentiometer or the -at least one- flight time measurement sensor associated with the starting line (LD) (respectively the finishing line (LA)) is connected to a microcontroller capable of transmitting information relating to the first transverse position (P1) (respectively to the second transverse position (P2)), via a wireless communication protocol.
Method for determining at least one friction parameter according to the preceding claim, in which the microcontrollers implemented in the method are synchronized using GNSS receiver modules.
Method for determining at least one friction parameter according to one of the preceding claims, in which the width (l) of the starting line (LD) and/or the width (l) of the finishing line (LA) is between 0.2m and 5m.
Method for determining at least one friction parameter according to one of the preceding claims, in which the starting line (LD) and the finishing line (LA) coincide, the section of track or road defining a loop.
Method for determining at least one friction parameter according to one of the preceding claims, in which the first (P1) and the second (P2) transverse positions are time-stamped when they are measured.
Method for determining at least one friction parameter according to one of the preceding claims, involving one or more movements on the section of track or road by the cyclist, and comprising for each movement: - a measure of the difference in kinetic energy of the cyclist between the finish line (LA) and the start line (LD), - a measurement of the driving energy developed by the cyclist, if applicable, during his movement on the section between the starting line (LD) and the finishing line (LA), - a direct or indirect measurement of the dynamic air pressure during the cyclist's movement on the section between the start line (LD) and the finish line (LA), so as to draw a relationship linking a resistive force (F res ) to an average dynamic air pressure (<P air >), the mass of the cyclist being known and the altitude difference (H) between the starting line (LD) and the finishing line (LA) being determined from the first (P1) and second (P2) transverse positions.
Method for determining at least one friction parameter according to the preceding claim, in which the relationship linking the resistive force (F res ) to the average dynamic air pressure (<P air >) is linear and an aerodynamic drag surface (CxS), the directing coefficient of the line, and a rolling coefficient (C r ), proportional to the coordinate at the origin of the line, are determined.
Apparatus for measuring a transverse position (P1, P2) of the cyclist's passage on a starting line (LD) or finishing line (LA) and its time stamp, intended to be implemented in a method for determining at least one friction parameter according to claim 10, comprising: - a resistive membrane potentiometer arranged on the starting line (LD) or finishing line (LA), the dimension (D) of the potentiometer along a transverse axis being equal to a transverse extent or width (l) of the starting line (LD) or finishing line (LA), the potentiometer comprising three pins and having a fixed resistance between a first pin and a third pin and a variable resistance between the second pin and a third pin, said variable resistance being proportional to the transverse position (y) of passage of the cyclist along the dimension (D); - a microcontroller to which the resistive membrane potentiometer is connected, the second pin of the resistive membrane potentiometer being connected to an analog input of the microcontroller allowing voltage variations representative of the transverse position (P1, P2) of the cyclist's passage to be read and timestamped.
Apparatus for measuring a transverse position of passage of the cyclist on a starting line (LD) or finishing line (LA) and its time stamp, intended to be implemented in a method for determining at least one friction parameter according to claim 10, comprising: - two resistive membrane potentiometers arranged parallel and side-by-side on the starting line (LD) or finishing line (LA), the dimension (D) of each potentiometer along a transverse axis being equal to a transverse extent or width (l) of the starting line (LD) or finishing line (LA), each potentiometer comprising three pins and having a fixed resistance between a first pin and a third pin and a variable resistance between the second pin and a third pin, said variable resistance being proportional to the transverse position (y) of passage of the cyclist along the dimension (D); - a microcontroller to which the two resistive membrane potentiometers are connected, the second pin of the first resistive membrane potentiometer being connected to an analog input of the microcontroller for reading the transverse position of the cyclist's passage, the second pin of the second resistive membrane potentiometer being connected to an interrupt of the microcontroller so as to trigger the time stamp with a precision better than +/-100ms.
Apparatus according to one of claims 13 and 14, comprising wireless communication means for transmitting information relating to the transverse position (P1, P2) of the cyclist's passage and relating to its time stamp.

Description

METHOD FOR DETERMINING AT LEAST ONE FRICTION PARAMETER OF A CYCLIST IN REAL MOVEMENT CONDITIONS, AND ASSOCIATED DEVICES FIELD OF THE INVENTION The present invention relates to the field of devices and methods for measuring and determining resistive forces exerted on a cyclist in motion. The invention aims in particular to determine parameters characterizing the resistive forces such as the aerodynamic drag surface and/or the rolling coefficient of the cyclist on his bicycle, with precision, reproducibility and by implementing a simple and rapid protocol. TECHNOLOGICAL BACKGROUND OF THE INVENTION There are two categories of tests to measure key cyclist friction parameters (rolling and aerodynamics): stationary tests (wind tunnel) and in-motion tests (real-world riding conditions). Real-world tests are particularly interesting because they can take into account parameters related to the cyclist's posture during effort and movement. As explained in document WO2022074330A1, a cyclist in motion is subjected to several forces (gravity force, rolling force, friction force with the air, forward force). In order to minimize the energy cost of the vehicle's movement, it appears particularly key to know how to accurately measure the frictions applied to the cyclist (rolling and aerodynamics). The methods for determining the aerodynamic drag surface and the rolling coefficient proposed by this document, based on the principle of conservation of energy, generally offer excellent reproducibility as well as great simplicity of implementation. It was nevertheless observed that in certain test route conditions, short and involving a sloping road (for example on a velodrome track), the level of precision for the determination of the friction parameters was lower than expected. SUBJECT OF THE INVENTION The present invention aims to remedy all or part of the aforementioned drawbacks. It concerns a method for determining at least one friction parameter of a cyclist in real travel conditions, on a section of track or road with a slope. BRIEF DESCRIPTION OF THE INVENTION The invention relates to a method for determining at least one friction parameter of a cyclist in real travel conditions, on a section of track or road having a slope and extending longitudinally from a starting line to a finishing line over a length, each of the starting and finishing lines extending transversely over a width. The method, based on an equation derived from the principle of conservation of energy, is remarkable in that it includes a step of measuring a first transverse position of the cyclist's passage on the starting line and a second transverse position of the cyclist's passage on the finishing line, each of the first and second transverse positions being determined along the width with an accuracy of +/-5cm. According to other advantageous and non-limiting characteristics of the invention, taken alone or in any technically feasible combination: the measuring step involves at least one membrane potentiometer arranged on the starting line and on the finishing line, along the width; the membrane potentiometer is held on a rigid strip, which is arranged on the starting line (respectively on the finishing line), along the width; the measurement step involves at least one time-of-flight sensor, opposite each of the start and finish lines; each of the first and second transverse positions is determined on the width with a precision of +/-4cm, or even +/-3cm, +/-2cm, or even +/-1cm; the -at least one- membrane potentiometer arranged on the starting line (respectively the finishing line) or the -at least one- time-of-flight measuring sensor associated with the starting line (respectively the finishing line) is connected to a microcontroller capable of transmitting information relating to the first transverse position (respectively to the second transverse position), via a wireless communication protocol; the microcontrollers implemented in the process are synchronized using GNSS (global navigation satellite systems) receiver modules; the width of the starting line and/or the width of the finishing line is between 0.2m and 5m; the starting line and the finishing line are the same, the section of track or road defining a loop; the first and second transverse positions are precisely time-stamped when measured; the process involves one or more movements on the section of track or road by the cyclist, and includes for each movement: - a measure of the difference in kinetic energy of the cyclist between the finish line and the start line, - a measure of the motive energy developed by the cyclist, if applicable, during his movement on the section between the starting line and the finishing line, - a direct or indirect measurement of the dynamic air pressure as the cyclist moves along the stretch between the start line and the finish line, so as to draw a relationship linking the resistive force to the average dynamic air pressure, the mass of the cyclist being