SYSTEM FOR A SHOE SOLE, METHOD FOR OPERATING THE SYSTEM, A SHOE SOLE, AND A SHOE

Abstract

Systems for a shoe sole with at least one piezoelectric element for generating electrical energy. In some embodiments, a system for a shoe sole comprises (a.) at least one piezo element adapted to produce an electrical signal upon mechanical deformation of the at least one piezo element, (b.) at least one first energy storage and at least one second energy storage, wherein the at least one first energy storage and the at least one second energy storage are adapted to store electrical energy obtained from the electrical signal, and (c.) at least one converter unit adapted to selectively control a transfer of an amount of electrical energy between the at least one first energy storage and the at least one second energy storage.

Claims

1. A system for a shoe sole, comprising: at least one piezo element adapted to produce an electrical signal upon mechanical deformation of the at least one piezo element; at least one first energy storage and at least one second energy storage, the at least one first energy storage and the at least one second energy storage being adapted to store electrical energy obtained from the electrical signal; and at least one converter unit adapted to selectively control a transfer of an amount of electrical energy between the at least one first energy storage and the at least one second energy storage.

2. The system of claim 1, wherein the at least one converter unit is adapted to selectively control the transfer of an amount of electrical energy based at least in part on a switching frequency between a charge state and a discharge state of the at least one converter unit.

3. The system of the claim 2, wherein the switching frequency is based at least in part on the electrical signal of the at least one piezo element, an overall power used by the system, or both.

4. The system of claim 2, further comprising a control unit adapted to calculate the switching frequency.

5. The system of claim 2, wherein the charge state has a duration in the range of 20 ns to 180 ns.

6. The system of claim 1, wherein the at least one converter unit has an active mode and a non-active mode, wherein a transition between the active mode and the non-active mode is based at least in part on a lower converter threshold, an upper converter threshold, or both thresholds for the electrical energy measured at the at least one first energy storage and wherein the selective control of the at least one converter unit is only provided in the active mode.

7. The system of claim 1, wherein the at least one converter unit is a flyback converter having a primary transformer side connected with the at least one first energy storage and a secondary transformer side connected with the at least one second energy storage.

8. The system of claim 2, wherein the electrical energy is transferred from the at least one first energy storage to the at least one converter unit in the charge state and the electrical energy is transferred from the at least one converter unit to the at least one second energy storage in the discharge state.

9. The system of claim 2, wherein the at least one converter unit comprises a metal oxide semiconductor field-effect transistor switch adapted to switch the at least one converter unit between the charge state and the discharge state.

10. The system of claim 2, further comprising a power management unit adapted to generate a control signal to switch the at least one converter unit between the charge state and the discharge state.

11. The system of claim 1, further comprising at least one third energy storage adapted to store electrical energy obtained from the electrical signal and to provide electrical energy to the at least one second energy storage when the electrical signal from the at least one piezo element drops below a piezo threshold of electrical energy.

12. The system of claim 1, further comprising at least one regulator unit adapted to switch between a regulating mode and a non-regulating mode of the at least one regulator unit based at least in part of a regulation threshold of electrical energy.

13. The system of claim 12, wherein the regulating mode causes the at least one second energy storage staying in a regulated voltage range between 1.0 to 4.0 V so that electrical energy accumulates in the at least one first energy storage.

14. The system of claim 12, further comprising at least one comparator unit adapted to measure the regulation threshold of electrical energy.

15. The system of claim 1, further comprising at least one rectifying unit adapted to convert the electrical signal.

16. The system of claim 15, further comprising at least one of a signal processing unit, a first comparator unit, a second comparator unit, a first switching unit, a second switching unit, a third switching unit, or a battery unit, wherein the system comprises at least one of the following arrangements: the at least one piezo element is connected to the signal processing unit; the at least one rectifying unit is connected between the at least one piezo element and the at least one first energy storage; the at least one first energy storage is connected to at least one of the at least one regulator unit, the at least one converter unit, or the power management unit; the at least one regulator unit is connected between the at least one first energy storage and the at least one second energy storage, and is connected to the second comparator unit; the at least one converter unit is connected to at least one of the at least one first energy storage, the at least one second energy storage, or the power management unit; the at least one second energy storage is connected to at least one of the at least one third energy storage by one of the first switching unit, the first comparator unit, or the second comparator unit; the first comparator unit is connect with the first switching unit; the at least one third energy storage is connected to at least one of the battery unit, the control unit, and the power management unit; the control unit is connected to the power management unit; and the power management unit is connected to at least one of the signal processing unit, the second switching unit, or the third switching unit.

17. The system of claim 1, wherein the system is integrated into a cavity of an insole, a midsole or an outsole of a shoe.

18. The system of claim 1, wherein at least two piezo elements are arranged in a heel area and/or a forefoot area of the shoe sole.

19. A shoe sole comprising the system of claim 1.

20. A shoe comprising the shoe sole of claim 20.

21. A method for operating the system of claim 1, the method comprising: generating the electrical signal upon mechanical deformation of the at least one piezo element; and selectively controlling the transfer of an amount of electrical energy between the at least one first energy storage and the at least one second energy storage.

22. The method of claim 21, wherein selectively controlling comprises switching at least one converter unit between a charge state and a discharge state by using a switching frequency and wherein the electrical energy is transferred from the at least one first energy storage to the at least one converter unit in the charge state and the electrical energy is transferred from the at least one converter unit to the at least one second energy storage in the discharge state.

23. The method of claim 22, further comprising calculating the switching frequency.

24. The method of claim 21, further comprising switching the system between an active mode and a non-active mode or between a regulating mode and a non-regulating mode, or between both modes.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In the following, exemplary embodiments of the present disclosure are described with reference to the figures:

[0034] FIG. 1 shows an exemplary schematic diagram of a system for a shoe sole according to the present disclosure.

[0035] FIGS. 2A and 2B illustrate the circuit and operation of a converter unit in a system for a shoe sole according to the present disclosure.

DETAILED DESCRIPTION

[0036] Some embodiments of the disclosure are described in detail with reference to a system for a shoe sole comprising at least one piezoelectric element and other electronic components, such as energy storages and at least one converter unit. However, the concept of the present disclosure may identically or similarly be applied to other parts of the shoes to generate and store electrical energy from the mechanical deformation of the piezoelectric elements, like the shoe upper. Moreover, this concept may also identically or similarly be applied to any sports equipment or functional sportswear with sufficient mechanical deformation for piezoelectrics, such as a ball, e.g. for soccer, rugby, American football, basketball, baseball etc., or such as shirts, clothes, socks, underwear, or to a piece of sports equipment such as a tennis racket, golf club, baseball bat, badminton racket, cricket bat, ice-hockey stick, hockey stick, ice skating blades, sledding attachments, jumping attachments, attachments with wheels, attachments with springs, fin-like attachments, attachments that allow hovering, flying, squash racket, table-tennis bat, boxing gloves, ski, snowboard, kite, and the like.

[0037] It is to be understood that these exemplary embodiments may be modified in a number of ways and combined with each other whenever compatible and that certain features may be omitted in so far as they appear dispensable.

[0038] It should be noted that the terms of “voltage”, “energy”, “power”, “charge” and “current” as used in the present application may be connected by the known equations for the capacitance, electrical energy, and power in electrical circuits: C=Q/V, where C is capacitance, Q is charge, and V is voltage; W=0.5*C*V2, where W is electrical energy, C is capacitance, and V is voltage; and P=V*I, where P is electrical power, V is voltage and I is current.

[0039] Moreover, the terms “piezo” and “piezoelectric” as used in the present application may be interchangeable. The same applies for the terms “electric” and “electrical”.

[0040] FIG. 1 shows an exemplary schematic diagram of a system 100 for a shoe sole comprising a piezo element 105 (e.g., a piezo generator) according to the disclosure. In the following, the operation of the system 100 will be described in more detail.

[0041] At the beginning, the system 100 is empty of charge/current/voltage, no electrical energy is stored and units (or electrical components) using electrical energy are set to OFF.

[0042] As described before, the piezo element 105 (e.g., a piezo generator) creates an electrical signal or current as a result of a mechanical deformation. It is noted that also other types of elements capable of creating electrical current from mechanical strain may be used to realize the disclosure.

[0043] Information about the created electrical current (or input voltage) at the piezo element 105 is obtained by the signal processing unit 107 and may later be provided to the power management unit 110 (e.g., a control logic).

[0044] The electrical current from the piezo element 105 is then conveyed to the rectifier unit 112 that converts the alternating current (AC) signal of the piezo element 105 into a direct current (DC) signal.

[0045] Moreover, it is pointed out that various sensors may be used in connection with the system 100. For example, anyone or combinations of an accelerometer, a gyroscope, a magnetometer, a pressure sensor and a position sensor may be used with the system 100. In one example, these sensors may be controlled by the power management unit 110, which is adapted for controlling the remainder of the system 100, and the sensors may obtain the electrical energy needed for operating them from the energy storages as described herein. Thus, a self-sustaining system 100 with one or more sensors (e.g., accelerometer, gyroscope, magnetometer and/or position sensor), wherein the created electrical energy is used as both, sensor signal and energy for operating the system 100, may be realized by other types of elements (e.g., of an electromagnetic type comprising a body, with permanent magnetization, configured to move within a coil, wherein the movement is created by exerting pressure on the element).

[0046] The first energy storage 115 (e.g., a first capacitor) is loaded first by the electrical signal and the corresponding voltage in the first capacitor will rise (V=Q/C), where C is capacitance, Q is charge and V is voltage.

[0047] The electrical current is then passing through the regulator unit 120. The regulator unit 120 may be a junction field-effect transistor, JFET, regulator. At the beginning of operation, the regulator unit 120 is in a non-regulating mode so that the electrical current directly flows into the second energy storage 125 (e.g., a second capacitor).

[0048] When the voltage in the second energy storage 125 exceeds a certain voltage level, a first comparator unit 130 controls a first switching unit 135 so that electrical current is conveyed into the third energy storage 140 (e.g., a third capacitor). At the same time, the power management unit 110 is powered and set to ON.

[0049] The voltage level detection method of the first comparator unit 130 may be used with a resistor bridge that is in series with load switch components, which are connected to capacitors. Also direct voltage measurement methods may be used.

[0050] The first energy storage 115, the second energy storage 125 and the third energy storage 140 may be capacitors, supercapacitors, thin film Lithium batteries, or other types of suitable energy storages (e.g. any battery). Of course, various combinations of any of these types may be used. For instance, the first energy storage 115 may be a capacitor, and the second energy storage 125 may be a thin film lithium battery. In this way, different properties and advantages of the respective type of energy storage may be optimally used. As an example, an energy storage of a first type may quickly charge but cannot hold the stored energy for a longer time period. Another energy storage may need longer to charge but be able to store the energy for a longer time period.

[0051] In case the voltage in the second energy storage 125 exceeds the regulation threshold of electrical energy measured by the second comparator unit 147, the regulator unit 120 switches in a regulating mode so that the second energy storage 125 and/or the third energy storage 140 may stay in a regulated voltage range between 1.0 V to 4.0 V, or between 1.5 V to 3.5 V, or between 2.0 V to 3.0 V. In this regulated voltage range, the voltage in the first energy storage 115 may rise and electrical energy may accumulate (W=0.5*C*V2), where W is electrical energy, C is capacitance, and V is voltage.

[0052] As soon as the voltage in the first energy storage 115 exceeds the upper converter threshold, the converter unit 150 (e.g., a flyback converter as will be described later) will get into from the non-active mode into the active mode to selectively control the transfer of an amount of electrical energy between the first energy storage 115 and the second energy storage 125.

[0053] In the active mode, the converter unit 150 transfer charge (or electrical energy) from the first energy storage 115 to the second energy storage 125 by electrical power conversion as explained above. In this way, selectively controlling between the first energy storage 115 and the second energy storage 125 according to the convention may be obtained.

[0054] This transfer of electrical energy is done with a certain (switching) frequency causing the converter unit 150 to switch between a charge state and a discharge state (as will be explained later with respect to FIGS. 2A and 2B). This switching of the converter unit 150 may be adapted so that the amount of charge to be transferred (and thus the amount of electrical energy) may be selectively controlled. At a higher switching frequency, more charge may be transferred in the same amount of time during the active mode because the charge state may occur more often.

[0055] The active or non-active mode of the converter unit 150 is based on the input voltage of the first energy storage 125 from the piezo element 105, namely the upper converter threshold and the lower converter threshold. In one example, the power management unit 110 may check every 200 ms the voltage level in the first energy storage 125. Depending on the specific properties, other time intervals for checking the voltage level may also be applicable, such as every 50 ms, 100 ms, 300 ms or 500 ms.

[0056] When in active mode, the power management unit 110 generates a control (switching) signal and sends it to the converter unit 150. This control (switching) signal manages the converter unit's charge and discharge state by using a metal oxide semiconductor field-effect transistor, MOSFET, switch (not shown). Other FET-based switches are also conceivable.

[0057] When the converter unit 150, e.g., a flyback converter, is in the charge state (e.g., the MOSFET switch is conducting), electrical energy is loaded from the first energy storage 115 to the primary transformer side of the flyback converter 150. The duration of the charge state may be defined in the power management unit 110 (e.g., in the range of 20 ns to 180 ns, or in the range of 50 ns to 150 ns, or in the range of 80 ns to 120 ns, or in the range of about 100 ns or 200 ns to 400 ns, or in the range of 250 ns to 350 ns, or in the range of 275 ns to 325 ns or 225 ns to 275 ns, or about 300 ns).

[0058] As soon as the converter unit 150 switches into the discharge state (e.g., the MOSFET switch is non-conducting), the electrical energy is transferred from the primary transformer side into the secondary transformer side of the converter unit 150 and then to the second energy storage 125. These charge-discharge-switches may be scheduled periodically while the converter unit 150 is the active mode and may be referred to the selective control according to the present application. The frequency of this scheduling is the mentioned switching frequency and may be adapted by the power management unit 110 as explained above.

[0059] When charge (or electrical energy) moves into the primary transformer side of the converter unit 150, the voltage in the first energy storage 115 will drop. As soon as the voltage in the first energy storage 115 drops below the lower converter threshold, the converter unit 150 will get into the non-active mode and the power management unit 110 may stop the mentioned control signal switching.

[0060] It is pointed put that the duration of the converter unit 150 being in the active mode may be measured and may be used to adjust the switching frequency, wherein the optimal switching frequency may depend on the charge created in the piezo element 105 and/or the overall power that is used by the system 100. In this way, the optimal switching frequency may either be determined by a calculation in the control unit 155 (e.g., a microcontroller) and/or within the power management unit 110. Once determined, this switching frequency may be used in the power management unit 110 to switch the charge and discharge state of the converter unit 150. Therefore, the converter unit 150 may operate in the optimal mode.

[0061] The power management unit 110 may cause at least one of the following once certain voltage levels are sufficient: the second switching unit 160 and/or the third switching unit 170 to switch on, the supercapacitor storage 165 and/or the control unit 155 to wake up.

[0062] The second energy storage 125 and/or the third energy storage 140 may be supplied from the supercapacitor storage 165 (or a battery) if the electrical signal from the piezo element 105 is too less or stopped.

[0063] In addition, the electrical energy from the third energy storage 140 may also be used for other purposes, like fast start-up of the system 100. In this way, the system 100 may manage itself based on self-harvested energy. Nevertheless, the system 100 may be designed to have a very low power consumption.

[0064] The energy storages mentioned above may be one or more of a capacitor, supercapacitor, thin film Lithium battery or other suitable types of energy storages (e.g. any battery) which has a lower power leakage and small dimensions. The firmware of the control unit 155 may be designed in a way that it is in sleep mode when not used. This allows for a lower power consumption and a more efficient use of energy.

[0065] FIGS. 2A and 2B illustrate the circuit and operation of a converter unit in a system (e.g., converter unit 150 in system 100 as described for FIG. 1) for a shoe sole according to the present disclosure.

[0066] FIG. 2A shows an exemplary circuit diagram of the converter unit, wherein the converter unit is a flyback converter 200 in the active mode similar to the converter unit 150 in FIG. 1. In the following, the operation of the flyback converter 200 in the active mode will be described in more detail.

[0067] As mentioned, the flyback converter 200 as a transformer 205 may be used for direct currents conversion, DC/DC conversion, with galvanic isolation between the input voltage 210, e.g., from a piezo element (not shown, but similar to the piezo element 105) and the output voltage 230. The input voltage 210 (and the corresponding electrical energy) is applied to the first capacitor 215 (similar to the first energy storage 115) and the output voltage 230 (and the corresponding electrical energy) is applied to the second capacitor 235 (similar to the second energy storage 125).

[0068] When in active mode, a power management unit (similar to the power management unit 110) generates a control (switching) signal 240 and sends it to the flyback converter 200 by using a metal oxide semiconductor field-effect transistor, MOSFET, switch 247. As mentioned, this control (switching) signal 240 together with the MOSFET switch 247 may manage the charge state and the discharge state of the flyback converter 200 for the selective control of the transfer of an amount of electrical energy between the first capacitor 215 and the second capacitor 235.

[0069] When the MOSFET switch 247 is conducting, the flyback converter 200 is in the charge state. Electrical energy is then loaded from the first capacitor 215 to the primary transformer side 242 of the flyback converter 200. The duration of the charge state may be defined in the power management unit, as explained above (e.g., in the range of 20 ns to 180 ns, or in the range of 50 ns to 150 ns, or in the range of 80 ns to 120 ns, or in the range of about 100 ns or 200 ns to 400 ns, or in the range of 250 ns to 350 ns, or in the range of 275 ns to 325 ns, or in the range of 225 ns to 275 ns).

[0070] When the MOSFET switch 247 is non-conducting the flyback converter 200 is in the discharge state. The electrical energy is then transferred from the primary transformer side 242 into the secondary transformer side 245 of the flyback converter 200.

[0071] This electrical energy is further transferred via a rectifier unit 250, e.g., a rectifying diode, to the second capacitor 235. The transitions (or switches) between the charge state and the discharge state of the flyback converter 200 may be scheduled periodically with the mentioned switching frequency applied by the combination of the power management unit and the MOSFET switch 247.

[0072] FIG. 2B illustrates the different modes and different states of the flyback converter 200 changing over time (from left to right) and depending on the input voltage 210, e.g., from the piezo element (not shown, but similar to the piezo element 105). The active mode 255 or the non-active mode 265 of the flyback converter 200 are based on two specific input voltages 210 at the first capacitor 215, namely the lower converter threshold 270 (for the non-active mode 265) and the upper converter threshold 275 (for the active mode 255).

[0073] When the input voltage 210 in the first capacitor 215 exceeds the upper converter threshold 275, the flyback converter 200 will get into the active mode 255, as explained above.

[0074] During this mode, the flyback converter 200 switches between the charge state 285 and the discharge state 290 with the switching frequency 280.

[0075] In the charge state 285, electrical energy is loaded from the first capacitor 215 to the primary transformer side 242 of the flyback converter 200. When in the discharge state 290, the electrical energy is then transferred from the primary transformer side 242 into the secondary transformer side 245 of the flyback converter 200.

[0076] The duration of the charge state 285 may be seen as pulse durations of charging time. In FIG. 2B, there are four distinct (energy or charge) pulses during four charge states 285. At a higher switching frequency 280, more pulses (or charge states 285) in the active mode 255 may occur so that more total charge (and consequently a higher amount of electrical energy) may be transferred in the same amount of time.

[0077] When the input voltage 210 in the first capacitor 215 drops below the lower converter threshold 270, the flyback converter 200 will get into the non-active mode 265 and switching between the charge state 285 and the discharge state 290 stops.

[0078] As soon as the input voltage 210 in the first capacitor 215 exceeds again the upper converter threshold 275, the flyback converter 200 will get back into the active mode 255 and switching between the charge state 285 and the discharge state 290 will continue.

[0079] The following section describes aspects of the present disclosure:

[0080] Aspect 1 of the description—A system for a shoe sole, includes: at least one piezo element adapted to produce an electrical signal upon mechanical deformation of the at least one piezo element; at least one first energy storage and at least one second energy storage, the at least one first energy storage and the at least one second energy storage being adapted to store electrical energy obtained from the electrical signal; and at least one converter unit adapted to selectively control a transfer of an amount of electrical energy between the at least one first energy storage and the at least one second energy storage.

[0081] Aspect 2 of the description—The system according to aspect 1, wherein the at least one converter unit is adapted to selectively control the transfer of an amount of electrical energy based at least in part on a switching frequency between a charge state and a discharge state of the at least one converter unit.

[0082] Aspect 3 of the description—The system according to aspect 2, wherein the switching frequency is based at least in part on the electrical signal of the at least one piezo element and/or an overall power used by the system.

[0083] Aspect 4 of the description—The system according to one of aspects 2 or 3, further comprising a control unit adapted to calculate the switching frequency.

[0084] Aspect 5 of the description—The system according to one of aspects 2-4, wherein the charge state has a duration in the range of 20 ns to 180 ns, or in the range of 50 ns to 150 ns, or in the range of 80 ns to 120 ns, or in the range of about 100 ns or 200 ns to 400 ns, or in the range of 250 ns to 350 ns, or in the range of 275 ns to 325 ns, or in the range of 225 ns to 275 ns, or about 300 ns.

[0085] Aspect 6 of the description—The system according to one of aspects 1-5, wherein the at least one converter unit has an active mode and a non-active mode, wherein a transition between the active mode and the non-active mode is based at least in part on a lower converter threshold and/or an upper converter threshold for the electrical energy measured at the at least one first energy storage and wherein the selective control of the at least one converter unit is only provided in the active mode.

[0086] Aspect 7 of the description—The system according to one of aspects 1-6, wherein the at least one converter unit is a flyback converter having a primary transformer side connected with the at least one first energy storage and a secondary transformer side connected with the at least one second energy storage.

[0087] Aspect 8 of the description—The system according to one of aspects 2-7, wherein the electrical energy is transferred from the at least one first energy storage to the at least one converter unit in the charge state and the electrical energy is transferred from the at least one converter unit to the at least one second energy storage in the discharge state.

[0088] Aspect 9 of the description—The system according to one of aspects 2-8, wherein the at least one converter unit comprises a metal oxide semiconductor field-effect transistor, MOSFET, switch adapted to switch the at least one converter unit between the charge state and the discharge state.

[0089] Aspect 10 of the description—The system according to one of aspects 2-9, further comprising a power management unit adapted to generate a control signal to switch the at least one converter unit between the charge state and the discharge state.

[0090] Aspect 11 of the description—The system according to one of aspects 1-10, further comprising at least one third energy storage adapted to store electrical energy obtained from the electrical signal and to provide electrical energy to the at least one second energy storage when the electrical signal from the at least one piezo element drops below a piezo threshold of electrical energy.

[0091] Aspect 12 of the description—The system according to one of aspects 1-11, further comprising at least one regulator unit, such as a junction field-effect transistor, JFET, regulator, adapted to switch between a regulating mode and a non-regulating mode of the at least one regulator unit based at least in part of a regulation threshold of electrical energy.

[0092] Aspect 13 of the description—The system according to aspect 12, wherein the regulating mode causes the at least one second energy storage staying in a regulated voltage range between 1.0 V to 4.0 V, or in the range of 1.5 V to 3.5 V, or in the range of 2.0 V to 3.0 V, or in the range of 2.0 V to 5.5 V, or in the range of 3.0 V to 4.2 V so that electrical energy accumulates in the at least one first energy storage.

[0093] Aspect 14 of the description—The system according to one of aspects 12 or 13, further comprising at least one comparator unit adapted to measure the regulation threshold of electrical energy.

[0094] Aspect 15 of the description—The system according to one of aspects 1-14, further comprising at least one rectifying unit adapted to convert the electrical signal.

[0095] Aspect 16 of the description—The system according to aspect 15, further comprising at least one of a signal processing unit, a first comparator unit, a second comparator unit, a first switching unit, a second switching unit, a third switching unit, or a battery unit, wherein the system comprises at least one of the following arrangements: the at least one piezo element is connected to the signal processing unit; the at least one rectifying unit is connected between the at least one piezo element and the at least one first energy storage; the at least one first energy storage is connected to at least one of the at least one regulator unit, the at least one converter unit, or the power management unit; the at least one regulator unit is connected between the at least one first energy storage and the at least one second energy storage, and is connected to the second comparator unit; the at least one converter unit is connected to at least one of the at least one first energy storage, the at least one second energy storage, or the power management unit; the at least one second energy storage is connected to at least one of the at least one third energy storage, such as by the first switching unit, the first comparator unit, or the second comparator unit; the first comparator unit is connect with the first switching unit; the at least one third energy storage is connected to at least one of the battery unit, such as by the second switching unit, the control unit, such as by the third switching unit, and the power management unit; the control unit is connected to the power management unit; and the power management unit is connected to at least one of the signal processing unit, the second switching unit, or the third switching unit.

[0096] Aspect 17 of the description—The system according to one of aspects 1-16, wherein the system is integrated into a cavity of an insole, a midsole or an outsole of a shoe.

[0097] Aspect 18 of the description—The system according to one of aspects 1-17, wherein at least two piezo elements are arranged in a heel area and/or a forefoot area of the shoe sole.

[0098] Aspect 19 of the description—A shoe sole comprising the system according to one of aspects 1-18.

[0099] Aspect 20 of the description—A shoe, such as a sports shoe, comprising the shoe sole according to aspect 19.

[0100] Aspect 21 of the description—A method for operating the system according to one of aspects 1-18, the method comprising: generating the electrical signal upon mechanical deformation of the at least one piezo element; and selectively controlling the transfer of an amount of electrical energy between the at least one first energy storage and the at least one second energy storage.

[0101] Aspect 22 of the description—The method according to aspect 21, wherein selectively controlling comprises switching the at least one converter unit between the charge state and the discharge state by using the switching frequency and wherein the electrical energy is transferred from the at least one first energy storage to the at least one converter unit in the charge state and the electrical energy is transferred from the at least one converter unit to the at least one second energy storage in the discharge state.

[0102] Aspect 23 of the description—The method according to aspect 22, further comprising calculating the switching frequency.

[0103] Aspect 24 of the description—The method according to one of aspects 21-23, further comprising switching the system between the active mode and the non-active mode and/or between the regulating mode and the non-regulating mode.

[0104] While various embodiments and aspects have been described herein, they have been presented by way of example, and not limitation. It should be apparent that adaptations and modifications are intended to be within the meaning and range of equivalents of the disclosed embodiments and aspects, based on the teaching and guidance presented herein. It therefore will be apparent to one skilled in the art that various changes in form and detail can be made to the embodiments and aspects disclosed herein without departing from the spirit and scope of the present disclosure. The elements of the embodiments and aspects presented herein are not necessarily mutually exclusive, but can be interchanged to meet various situations as would be appreciated by one of skill in the art.

[0105] Embodiments and aspects of the present disclosure are described in detail herein with reference to embodiments and aspects thereof as illustrated in the accompanying drawings, in which like reference numerals are used to indicate identical or functionally similar elements. References to “an embodiment,” “some embodiments,” “in certain embodiments,” “an aspect,” “some aspects,” “in certain aspects,” etc., indicate that the embodiment or aspect described can include a particular feature, structure, or characteristic, but every embodiment or aspect may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment or aspect. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment or aspect, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments and aspects whether or not explicitly described.

[0106] The examples are illustrative, but not limiting, of the present disclosure. Other suitable modifications and adaptations of the variety of conditions and parameters normally encountered in the field, and which would be apparent to those skilled in the art, are within the spirit and scope of the disclosure.

[0107] It is to be understood that the phraseology or terminology used herein is for the purpose of description and not of limitation. The breadth and scope of the present disclosure should not be limited by any of the above-described exemplary embodiments and aspects, but should be defined in accordance with the following claims and their equivalents.