METHOD OF CONTROLLING A FORCE AND/OR RESISTANCE GENERATOR OF AN EXERCISE APPARATUS

Abstract

The invention relates to a method, in particular a computer implemented method, of controlling a force and/or resistance generator of an exercise apparatus (1), which apparatus includes a plurality of physical transmission ratios (10, 4) between a user force input device (7-9) and the force and/or resistance generator and at least one shifter (12) to select a desired transmission ratio. The method includes the steps of determining the engaged physical transmission ratio, mapping the engaged physical gear ratio onto a virtual transmission ratio, and adapting the generated force and/or resistance based on the virtual transmission ratio.

Claims

1. A computer implemented method of controlling a force and/or resistance generator of an exercise apparatus, which exercise apparatus comprises a plurality of physical transmission ratios between a user force input device and the force and/or resistance generator and at least one shifter to select a desired transmission ratio, the method comprising: (a) determining an engaged physical transmission ratio, (b) mapping the engaged physical transmission ratio onto a virtual transmission ratio, and (c) adapting generated force and/or resistance generated by the force and/or resistance generator based on the virtual transmission ratio.

2. Method according to claim 1, wherein the engaged physical transmission ratio is determined from a difference in rotational speed of axles on both sides of a physical transmission of the exercise apparatus.

3. Method according to claim 1, wherein step (a) comprises: (a)(1) detecting a physical transmission shift, and (a)(2) determining the engaged physical transmission ratio from the detected physical transmission shift.

4. Method according to claim 1, comprising the steps of selecting a virtual transmission ratio, determining the selected virtual transmission ratio, and adapting the generated force and/or resistance based on the engaged virtual transmission ratio.

5. Method according to claim 1, wherein the exercise apparatus is a bicycle trainer, which bicycle trainer is configured to be coupled to a bicycle or parts of a bicycle, the combination of the bicycle trainer and the bicycle or parts of a bicycle comprising (i) one or more rear sprockets, (ii) a front chainring, and (iii) a chain passing over one of the one or more rear sprockets and the front chainring, defining a physical transmission ratio.

6. Method according to claim 5, comprising the step of determining a number of teeth of a rear sprocket or a diameter of a rear sprocket and/or a number of teeth of the front chainring or a diameter of the front chainring.

7. Method according to claim 1, wherein step (b) comprises selecting the virtual transmission ratio from a look-up table.

8. Method according to claim 7, wherein the look-up table comprises a plurality of virtual and user defined gears.

9. Exercise apparatus comprising: a frame; an axle rotatably mounted in or to the frame; a force input device coupled to the axle; a force and/or a resistance generator coupled to the axle via a transmission; and a computer configured to carry out the method of claim 1.

10. Exercise apparatus according to claim 9, further comprising sprockets and a free hub body or freewheel for mounting the sprockets-and configured to be placed in frictional contact with a rear wheel of the exercise apparatus, wherein the sprockets and the free hub body or freewheel are coupled to the force and/or resistance generator.

11. Exercise apparatus according to claim 9, further comprising an input device configured to electronically change the-virtual gears.

12. Exercise apparatus according to claim 11, wherein the input device comprises two switch sets, one switch set for shifting up and down the-virtual rear sprockets and one switch set for shifting up and down the-virtual front chain rings.

13. Exercise apparatus according to claim 11, wherein the computer is configured to receive input from a user to enter and/or amend the virtual gears.

14. (canceled)

15. A non-transitory computer-readable medium having stored thereon a computer program comprising instructions to control the exercise apparatus of claim 9.

16. Method according to claim 1, wherein the exercise apparatus is a bicycle trainer, which bicycle trainer is configured to be coupled to a bicycle or parts of a bicycle, the combination of the bicycle trainer and the bicycle or parts of a bicycle comprising (i) one or more rear pulleys, (ii) a front pulley, and (iii) a belt passing over one of the rear pulleys and the front pulley, defining a physical transmission ratio.

17. Method according to claim 16, comprising the step of determining a diameter of a rear pulley and/or a diameter of the front pulley.

18. Exercise apparatus according to claim 9, further comprising a roller configured to be placed in frictional contact with a rear wheel of the exercise apparatus, wherein the roller is coupled to the force and/or resistance generator.

Description

[0035] The invention will now be explained in more detail with reference to the Figures, which show preferred embodiments of the present invention.

[0036] FIG. 1 is a perspective view of a bicycle trainer according to the present invention.

[0037] FIG. 2 is diagram of a physical set of front and rear gears and a virtual set of front and rear gears.

[0038] FIG. 3 is a diagram of a method for virtual shifting and force feedback in accordance with the present invention.

[0039] FIG. 1 shows a smart trainer 1, comprising a frame 2 in a housing 3. A force generator, in this example an electric motor, is fixedly mounted to the frame and accommodated inside the housing. A cassette 4 of sprockets is mounted on the axle of the force generator or coupled to the axle of the force generator via a transmission, such as a belt drive. A computer 5 (FIG. 3), e.g. a single board computer, for controlling the force generator as well as sensors for measuring the angular speed of and the torque exerted on the axle carrying the sprockets are also accommodated inside the housing. More details on these components can be found in WO 2020/071913 A1.

[0040] A road bike 6, with its rear wheel and cassette removed, is mounted in the frame in a manner known in itself. The bike 6 comprises a user force input device, i.c. pedals 7 and cranks 8 rotatable about and fixed to a bottom bracket and to one or more e.g. two chain rings. A chain extends over one of the chain rings and one of the sprockets. The bike comprises, in a usual manner, shifters 12 to derail the chain and move it to another chain ring or sprocket to change the physical transmission ratio.

[0041] FIG. 2 shows, on the left-hand side, an example of a typical configuration for flat terrain and/or advanced level cyclists, namely two chain rings, one with 53 teeth and one with 39 teeth, in the front, and eleven sprockets having 11, 12 ... 21, 23 and 25 teeth in the rear, providing a fixed number of physical transmission ratios. The present invention enables the cyclist to use, with the physical setup described above, a different number and/or different transmission ratios on the smart trainer, e.g. to train at a different (virtual) terrain, e.g. via provider such as Zwift™ and Rouvy™ or a different level. An example of virtual gears is shown on the right-hand side of FIG. 2 and comprises two virtual chain rings, one with 50 teeth and one with 34 teeth in the front, and eleven sprockets having 12, 14 ... 30, 33 and 36 teeth in the rear.

[0042] FIG. 3 schematically shows a scheme for controlling the force generator. When a force, F.sub.ped, is applied to the padels, the cyclist will experience a resistive force, F.sub.res, from the force generator. The computer includes a kinetic model of the exercise apparatus, e.g. in the form of a software program, that is configured to receive an input and to generate a control signal for the force generator as an output. The kinetic model may be based on the equations of motions describing the behavior of the exercise apparatus and may further include external parameters relating to road conditions, e.g. wind and slope angle of the road in case of an exercise bike. This way, the kinetic model may accurately control the force generator to simulate certain exercise conditions, examples of such kinetic models are for example described in WO 2020/071913 and WO 2021186083.

[0043] Input from the sensors for angular speed and torque determine the force the athlete applies to the exercise apparatus and a computer may use this information as an input to the kinetic model of the exercise apparatus to generate the control signal for the force generator to generate a resistive force F.sub.res that opposes the force of the athlete, i.e. F.sub.ped≈ F.sub.res.

[0044] Mapping of the virtual gears can be carried out as follows: power at the pedals, P.sub.ped, is equal to power at the axle of the force generator, P.sub.wheel

[00001]$P_{ped}=P_{wheel}$

[00002]$F_{ped}.R_{ped}.2\pi .{\omega }_{ped}=F_{\mathrm{Re}s}.R_{wheel}.2\pi .{\omega }_{wheel}$

[0045] The angular speed of the axle, ω.sub.wheel is proportional to the angular speed of the pedals, ω.sub.ped, conform the ratio of the physical gears:

[00003]${\omega }_{wheel}=\frac{Gea{r}_{front}}{Gea{r}_{rear}}\cdot \omega {}_{ped}$

yielding

[00004]$F_{ped}=\frac{F_{Res}.R_{wheel}.2\pi .\frac{Gea{r}_{front}}{Gea{r}_{rear}}.{\omega }_{ped}}{R_{ped}.2\pi .{\omega }_{ped}}$

[00005]$F_{ped}=\frac{F_{Res}.R_{wheel}.\frac{Gea{r}_{front}}{Gea{r}_{rear}}}{R_{ped}}$

[0046] Note: required resistance is calculated in a manner known in itself, by adding forces resulting from wind, climbing, roll resistance, acceleration, etc., as mentioned above:

[00006]$F_{Res}=F_{wind}+F_{climb}+F_{roll}+.Math..Math.+m.a$

[0047] In a trainer, force at the pedals is defined by an overall virtual gear ratio, as follows:

[00007]$F_{ped}=F_{Res}.\frac{R_{wheel}}{R_{ped}}.\frac{Vir{t}_{Front}}{Vir{t}_{Rear}}$

[0048] In accordance with the present invention, mapping virtual gears onto physical gears is achieved e.g. by including 1) the physical transmission ratio between the front chain ring and the rear sprocket and 2) the reciprocal transmission ratio, as follows:

[00008]$\begin{array}{l}{F}_{ped}=F_{Res}.\frac{R_{wheel}}{R_{ped}}.\frac{Rea{l}_{Front}}{Rea{l}_{Rear}}.\frac{Rea{l}_{Rear}}{\mathrm{Re}a{r}_{Front}}.\frac{Vir{t}_{Front}}{Vir{t}_{Rear}}\\ \underset{\text{Physical Gearing}}{.Math.}\underset{\text{Virtual Impact}}{.Math.}\end{array}$

which yields front and rear mapping:

[00009]$\begin{array}{l}{F}_{ped}=F_{Res}.\frac{R_{wheel}}{R_{ped}}.\frac{Rea{l}_{Front}}{Rea{l}_{Rear}}.\frac{Vir{t}_{Front}}{Rea{l}_{Front}}.\frac{Rea{l}_{Rear}}{Vir{t}_{Rear}}\\ \underset{\text{Physical Gearing}}{.Math.}\underset{\begin{array}{l}\text{Front}\\ \text{Mapping}\end{array}}{.Math.}\underset{\begin{array}{l}\text{Rear}\\ \text{Mapping}\end{array}}{.Math.}\end{array}$

[0049] Operation is illustrated in FIG. 3 and involves measuring force and angular speed of the axle, determining the number of physical gear teeth in the front (e.g. 53, see FIG. 2)) and in the rear (e.g. 21), for example from variations in the rotational speeds over a period of time, update the physical gearing map, find the front ring index (e.g. index 2), find the rear sprocket index (e.g. index 9), lookup virtual front ring from index (index 2 corresponds to 50 virtual teeth, in FIG. 2), lookup virtual rear sprocket from index (index 9 corresponds to 30 virtual teeth, in FIG. 2), update force and angular speed, and adjust the force provided by the generator.

[0050] With the present invention, the physical gearing ratio that is selected by the rider is determined, preferably automatically, and subsequently used to map the physical gears onto virtual gears that may or may not be the same as the physical gears on the bicycle trainer. By adapting the formulas that calculate the resistance of the bike, the rider experiences the resistance as if he was riding on the virtual gears. Thus, the effect of the physical gearing can be eliminated from the resistance.

[0051] The invention is not restricted to the embodiments described above and can be varied in numerous ways within the scope of the claims. For example, in addition to direct drive trainers, the present invention is equally suitable for so-called wheel on trainers.