The present invention relates to the technical field bicycles.

In particular, the present invention relates to a method for identifying the transmission ratio selected by the cyclist while using the bicycle.

The collection of information concerning a person's performance during a physical activity arouses ever-increasing interest, particularly as it enables the progress made and the achievement of predetermined objectives to be known and assessed.

This is of particular interest and applicability in the bicycle sector.

In particular, when classical bicycles are used, the information that can be obtained allows the cyclist to know a great deal of data relating to his or her performance, which, in addition to being of interest, can also be useful for the definition and execution of specific training regimes or even the simple use of the bicycle.

Such information may in some respects be even more useful when collected and used in the context of pedal-assisted bicycles.

In fact, in this situation, the information acquired can also be used to determine the servo motor, that is, the contribution that the motor provides to pedalling, reducing the effort that the cyclist must exert to move the bicycle.

This is particularly interesting as the correct control of the electric motor's operation allows for an optimal balance between battery life and reduced cyclist effort.

In the context presented in the previous paragraphs, a parameter of great interest can be identified in the transmission ratio that is being used by the cyclist.

In fact, this parameter, especially if/when correlated with other data (such as the instantaneous speed of advancement of the bicycle) makes it possible to determine a range of useful information such as the cyclist's pedalling cadence. However, the identification of the specific transmission ratio used at a given moment would require the further introduction of expensive and complex instrumentation.

Therefore, there is a strong need in the industry to develop new methodologies that allow the identification of the transmission ratio in use at a given time without the need to install special instrumentation on the bicycle to detect this data.

In this context, the technical task underlying the present invention is to propose a method for identifying a transmission ratio that overcomes at least some of the drawbacks of the known technique mentioned above.

In particular, it is the object of the present invention to make available a method by which the transmission ratio selected by the rider while riding a bicycle can be indirectly detected without the need to introduce a special sensor.

The specified technical task and purposes are substantially achieved by a method for the identification of a transmission ratio, comprising the technical characteristics set forth in one or more of the attached claims.

According to the present invention, a method for identifying a transmission ratio is shown.

In particular, the method is applicable for the identification of the transmission ratio selected by the rider while using the bicycle.

This method finds advantageous application in the identification of the transmission ratio in use in a bicycle comprising a transmission that defines a plurality of different transmission ratios.

The method is performed by measuring at least one dimension of bicycle use.

Depending on the magnitude of use, an operating signal is generated, representing a time evolution of an instantaneous speed and/or instantaneous acceleration of the bicycle.

For each possible transmission ratio, the operating signal is filtered at a predefined filtering frequency. This filtering frequency is in particular equal to twice the instantaneous velocity measured in revolutions per second multiplied by the transmission ratio.

In this way, a respective plurality of independent filtered signals is generated from the plurality of transmission ratios.

The filtered signal with the highest instantaneous value among the plurality of filtered signals corresponds to the transmission ratio in use.

In other words, the transmission ratio in use is identified by selecting the one that is generating the highest of all the instantaneous values of the various filtered signals generated at any given time.

Advantageously, the method described herein makes it possible to identify indirectly the transmission ratio being used by the cyclist without the need to introduce an additional sensor specifically for this purpose, simply by exploiting the information that is acquired/processed by sensors of a different nature.

The dependent claims, included here for reference, correspond to different embodiments of the invention.

Further features and advantages of the present invention will become clearer from the indicative, and therefore non-limiting, description of a preferred but non-exclusive embodiment of a method for identifying a transmission ratio, as illustrated in the appended Figures:

- Figures 1A to 5 show representative graphs of the information acquired and obtainable by performing the method disclosed herein.

The method according to the present invention is aimed at identifying the transmission ratio being used by the cyclist at a given time.

In other words, performing the method described here makes it possible to determine which transmission ratio is in use at a given time among all the possible transmission ratios of the bicycle.

The method is therefore applicable on multi-gear bicycles, i.e. bicycles that include a gear defining a number of distinct transmission ratios. Operationally, the method is performed starting with a measurement of a magnitude of bicycle usage.

In other words, while the bicycle is being used, its operation is monitored in particular so as to generate an operational signal representing the time evolution of its instantaneous speed, of which a possible example is shown in Figure 1A, and/or its instantaneous acceleration, of which a possible example is shown in Figure 1 B.

In particular, Figure 1A shows a signal indicated as V representing the temporal evolution of the instantaneous velocity and an inclination signal P representing the inclination of the path followed by the bicycle.

Conversely, figure 1 B shows a signal indicated as C representative of the temporal evolution of the instantaneous acceleration and an inclination signal P representative of the inclination of the path followed by the bicycle. It should be noted that speed and acceleration are intrinsically linked quantities and therefore knowing one makes it possible to obtain/calculate the other by applying known procedures.

The operating signal is then filtered based on the transmission ratios of the bicycle.

In other words, for each possible transmission ratio, a separate and independent procedure of filtering the operating signal is performed, so as to obtain a corresponding plurality of filtered signals F (i.e. each filtered signal F is associated and generated as a function of a specific transmission ratio).

This filtering is performed for each transmission ratio at a filtering frequency equal to twice the instantaneous speed, measured in revolutions per second, multiplied by the respective transmission ratio.

In this way it is possible to obtain a plurality of filtered signals F in which each contains and represents only the contributions to the variation of the operating signal at a specific frequency directly dependent on the respective transmission ratio, thus identifying variations over time of the instantaneous speed or and/or instantaneous acceleration at the filtering frequency alone. In other words, each filtered signal F only includes contributions to changes in time of the operational signal dependent on the transmission ratio that uniquely determined the filtering frequency as a function of which said filtered signal F was generated.

It is therefore possible to identify as the transmission ratio in use the transmission ratio that led to the generation of the filtered signal F presenting the largest instantaneous value among the plurality of filtered signals F.

In fact, the Applicant has observed that, at any given moment, the greatest contribution to the variations/oscillations in the measured speed/acceleration values are due to the cyclist's pedalling, which has a frequency that can be calculated and is equal to the aforementioned filtering frequency, thus being directly dependent on and uniquely associated with the transmission ratio in use.

Flence, the filtered signal F presenting a filtering frequency corresponding to the cyclist's pedalling cadence calculated on the basis of the transmission ratio actually in use at a given moment will have higher instantaneous values than those of the other filtered signals F, which are instead filtered at frequencies at which there are no variations in speed/acceleration or at which such variations are due to environmental factors (wind, uneven terrain, climb/descent, or the like).

Figures 3 and 4 illustrate a possible example of execution of the method, in which 4 filtering frequencies X1 -X4 are identified, specifically shown in Figure 3, each associated and calculated as a function of a different transmission ratio.

In particular, it can be seen that such filtering frequencies are not constant but vary over time as they are calculated according to the formula f=2 ^* x ^* v, wherein f represents the filtering frequency, v represents the instantaneous forward speed measured in revolutions of the wheels per second and x represents the transmission ratio of the bicycle.

It follows that the filtering frequency for each transmission ratio varies over time as the instantaneous forward speed of the bicycle changes. Application of the filtering procedure to the operating signal leads to the generation of the corresponding filtered signals F indicated as Y1 -Y4 in Figure 4.

By way of example, it is evident that in the time interval between 15 seconds and 30 seconds in particular, signal Y3 has a higher instantaneous value than each of the other signals Y1 , Y2, Y4, and it is therefore possible to identify the transmission ratio in use as the ratio against which the filter frequency X3 was calculated.

Advantageously, a given transmission ratio can only be identified as the transmission ratio in use if the filtered signal F that it helped generate has an instantaneous value that remains greater than the instantaneous value of every other filtered signal F for a predefined time interval.

This avoids identifying as being in use a transmission ratio the corresponding filtered F-signal of which only presents a higher instantaneous value than the others due to a sudden and random fluctuation caused, for example, by the aforementioned environmental factors and not by a change of transmission ratio on the part of the cyclist.

In more detail, filtering of the operating signal can be performed by processing it through a band-eliminating filter B with a resonance frequency equal to the filter frequency.

Specifically, the operating signal is processed by the band-eliminating filter B in such a way as to generate a filter signal, and the filtered signal F is obtained by subtracting the filter signal from the operating signal. Alternatively, it is also possible to use a different filtering procedure by implementing a filter of a different nature or, at any rate, characterised by a different transfer function, as long as it can lead to the generation of filtered F signals influenced, determined and defined solely in dependence of the respective filtering frequency.

Preferably, the filtered signal F is evaluated against a base value. In other words, the filtered signal F makes it possible to identify the magnitude of oscillations in the operating signal at the filter frequency alone and with respect to an average value of these oscillations.

In this context, the filtered signal F which has the highest instantaneous modulus value at that instant is considered to be “greater”.

Advantageously, it is also possible to transmit to a remote terminal at least one of the usage magnitude, the operating signal, the transmission ratio in use and the filtered signal F generated according to the transmission ratio in use.

In particular, transmission can be via a wireless transmission protocol, such as Wi-FI®, Bluetooth® and/or via a cellular network.

The terminal to which the collected information is sent can instead be a smartphone, a smartwatch, a tablet or a fitband.

Furthermore, in accordance with a further aspect of the present invention, it is also possible to store at least one of the usage magnitude, the operating signal, the transmission ratio in use, and the filtered signal F generated as a function of the transmission ratio in use.

This storage can be on a readable storage medium installed on or connected to the remote terminal, for instance, or on a storage medium defined by an online database such as a computing cloud.

In addition, in addition to providing useful information to the cyclist, the ability to identify the transmission ratio in use has a particular relevance in the context of pedal-assisted bicycles.

The Applicant has in fact observed that fluctuations in instantaneous speed/acceleration values can be correlated with the degree of effort exerted by the cyclist during pedalling and therefore exploited to help drive the current delivered to the motor, thus determining its level of servo drive. In fact, the cyclist makes an effort (i.e. applies a force) specifically when pushing on the pedals.

The harmonic spectrum of the torque signal generated by the pedalling movement, a possible example of which is shown in Figure 2, is, as discussed above, strongly influenced by a frequency contribution of twice the pedalling frequency, i.e. it corresponds to the frequency at which the cyclist pushes on both pedals in the time it takes one pedal to complete a full revolution, which in turn is directly dependent on the transmission ratio in use.

Thus, the filtered signal F may further be used to determine the driving of the delivery of current to the electric motor of the pedal-assisted bicycle.

To this end, the filtered signal F corresponding to the transmission ratio in use (identified by the procedure described above) is processed to obtain an approximate signal A that is representative of an effort exerted by the cyclist; According to a preferred embodiment, the approximate signal A is obtained by applying to the filtered signal F a peak detection procedure, of which a possible example is illustrated in Figure 5, aimed at constructing an approximate signal A having a profile approximating the peaks of the filtered signal F. Preferably the peak detection procedure is applied to the module of the filtered signal F or alternatively to the only positive portion of said signal in such a way as to obtain a more significant result.

In more detail, peak detection is performed using non-linear peak detection by which an approximate signal A can be generated that approximates or follows the trend of the filtered signal F in accordance with a predefined set of rules, which are applied depending on the profile assumed by the filtered signal F itself.

In particular, the peak detection procedure may be performed by applying the following rules:

- if the filtered signal F is greater than the approximate signal A, the approximate signal A is set equal to the filtered signal F;

- if the filtered signal F is smaller than the approximate signal A, the approximate signal A follows a predetermined curve.

Said predetermined curve may for example follow a parabolic course.

In particular, in accordance with an aspect of the present invention, the predefined curve may exhibit a trend defined by the following rules: - if the filtered signal F is decreasing and smaller than the approximate signal A, the approximate signal A is decremented by a value equal to the filtered signal F multiplied by a first coefficient;

- if the filtered signal F is increasing and smaller than the approximate signal A, the approximate signal A is increased by a value equal to the filtered signal F multiplied by a second coefficient.

In this way, the approximate signal A follows the course of the filtered signal F until it overlaps with the latter in upward sections and instead decreases more slowly when the filtered signal F decreases so that it remains at higher values than the latter.

The value of the first and second coefficients may be selected according to how much the approximate signal A is to be superimposed on the filtered signal F, i.e. with what degree of approximation the filtered signal F is to be processed.

Alternatively, the filtered signal F can be processed in such a way as to generate an approximate signal A representative of its effective value, which is representative of a time course of the mean value of the oscillations in the operating signal determined by the cyclist's pedalling.

Regardless of the specific procedure implemented to obtain it, the approximate signal A is advantageously representative of the effort exerted by the cyclist.

It should be noted that, in general, the procedure described so far, and all the steps described herein for obtaining the approximate signal A, can be usefully employed for the evaluation/measurement of the effort exerted by a cyclist even in the use of conventional bicycles, i.e. bicycles without an electric motor, but in the specific context of electric bicycles it has the further advantage of providing an indication which can be used to manage the control of the current to be delivered to the electric motor.

Indeed, the greater the value assumed by the approximate signal A, the greater the current supplied to the electric motor and thus the greater the power generated by the latter to assist pedalling. In greater detail, an initial contribution used to generate a driving signal is obtained as a function of and dependent on the approximate signal A, and the delivery of current to the electric motor is controlled as a function of this driving signal.

Advantageously, the present invention achieves the proposed objects overcoming the drawbacks lamented in the prior art by providing the user with a method for identifying the transmission ratio in use while riding a bicycle in an indirect manner and thus without requiring the introduction of a specific dedicated sensor for acquiring this information.

In accordance with a dual aspect of the present invention, it is possible to perform the identification of the transmission ratio in use by processing the operational signal in the frequency domain instead of the time domain.

In particular, in accordance with this aspect of the present invention, at least one bicycle usage quantity is measured, again generating an operational signal representative of a time evolution of an instantaneous speed and/or instantaneous acceleration of the bicycle.

This operational signal is then transformed into the frequency domain using known techniques, thus generating a frequency signal.

This frequency signal is then processed to identify the specific frequency of the maximum energy contribution to the operating signal.

In other words, an operating frequency value is identified at which the frequency signal value is maximum.

The frequency at which the signal value is at its maximum, i.e. the operating frequency, therefore has the greatest contribution to the fluctuations of the operating value, i.e. the cyclist’s pedalling, as all other possible contributions due to possible environmental factors occur at different frequencies and are either zero or extremely minor compared to that generated by pedalling. Since fluctuations in the instantaneous speed value are directly related to pedalling cadence, which in turn depends on the transmission ratio in use, it is possible to calculate the transmission ratio in use by dividing the operating frequency by a value equal to twice the instantaneous speed measured in revolutions per second.

While presenting its own peculiarities, this second approach is dual to the one described above, in that starting from the same operating signal it makes possible the identification of the transmission ratio in use by processing this operating signal alternatively in the time domain or in the frequency domain.