Method for determining an angle of rotation of a rotatable component of a bicycle

Abstract

The invention relates to a method 100 for determining an angle of rotation D* of a rotatable component, such as a pedal crank shaft 4, of a bicycle 1 having at least one inductive angle of rotation sensor DW, wherein in particular reliably accurate angles of rotation D* of rotatable components with high mechanical loads are supplied. If the determined angle of rotation D* is used for open-loop or closed-loop control of an electric drive motor E or an actuator A, errors in the open-loop or closed-loop control of the electric drive motor E or the actuator A are prevented and thus a risk of an accident or injury to a rider of the bicycle 1 is minimized.

Description

[0001] ZF Friedrichshafen AG File 304854 Friedrichshafen 2023-08-07

[0002] Method for determining the angle of rotation of a rotatable component of bicycles

[0003] The present invention relates to a method for determining the angle of rotation of a rotatable component of bicycles, a control device, a computer program product and a computer-readable medium.

[0004] To control or regulate an electric drive motor in bicycles such as e-bikes, pedelecs, e-mountain bikes (eMTBs), cargo bikes, tricycles, quadricycles, or snow bikes, information about the rider's pedaling is often necessary. The intensity of the pedaling can be used to control or regulate the electrical power output of the electric drive motor. Pedaling or non-pedaling can be determined by measuring the cadence, also known as pedaling frequency, of the crank arm. This cadence can be determined, for example, by measuring the crank arm's rotation angle. WO2023148161 A1 discloses an inductive position sensor for determining the rotation angle of a crank arm in an electric bicycle. Such inductive position sensors for determining the position of a rotating component are also referred to as inductive angle sensors.An inductive rotary angle sensor comprises two opposing elements. These two elements are separated by an air gap and can rotate relative to each other without contact, while being electromagnetically coupled. The relative position of the two elements can be affected, particularly during sporty driving with high, fluctuating pedal forces, leading to measurement errors in determining the rotary angle. Such measurement errors can, in turn, result in incorrect control or regulation of the electric drive motor, thus increasing the risk of an accident.

[0005] The object of the present invention is to provide a method for determining the angle of rotation of a rotatable component, such as a crank axle, of bicycles using at least one inductive angle of rotation sensor, which in particular reliably delivers accurate angles of rotation of rotatable components subjected to high mechanical loads. Furthermore, if the determined angle of rotation is used for controlling or regulating an electric drive motor or an actuator, incorrect control or regulation of the electric drive motor or the actuator is prevented, thus minimizing the risk of an accident or injury to the cyclist.

[0006] The problem is solved by a method for determining the angle of rotation of a rotatable component of bicycles with the features of claim 1, a control device with the features of claim 12, a computer program product with the features of claim 13, and a computer-readable medium with the features of claim 14. Further embodiments are included in the dependent claims and are described below.

[0007] The invention claims a method, a control device for use on a bicycle such as e-bikes, pedelecs, e-mountain bikes (eMTBs), cargo bikes, tricycles, quad bikes or snow bikes, a computer program product and a computer-readable medium.

[0008] At the beginning of the process for determining the rotation angle of a rotatable component, such as a bicycle crank axle, using an inductive rotation angle sensor, a physical characterization of an air gap within the sensor is determined. Additionally, the rotation angle of the rotatable component is recorded by the sensor. Subsequently, previously stored data is retrieved from a data memory. From this data, at least one physical influence of the air gap can be determined, depending on the determined physical characterization of the air gap. The data can be presented as at least one interpolation table for an interpolation method. Alternatively, or preferably additionally, the data can be presented as at least one parameter value for a mathematical function.At least one correction value can be determined using the interpolation table and the interpolation method. Alternatively or additionally, at least one correction value can preferably be determined from the parameter value and the mathematical function. The correction value quantifies the physical influence of the air gap. Depending on the sensor-determined physical characterization of the air gap, the correction value is applied to correct the measured rotation angle. This ensures that the rotation angle of rotating components subjected to high mechanical stress, such as a crankshaft, is reliably and accurately determined. (ZF Friedrichshafen AG File 304854 Friedrichshafen 2023-08-07)From several measured rotation angles, for example of a crank arm, the angular velocity or cadence of the crank arm can be determined and used to control an electric drive motor or an actuator on the bicycle. Consequently, using the measured rotation angle can prevent incorrect control or regulation of the electric drive motor or actuator, thus minimizing the risk of an accident or injury to the cyclist.

[0009] The term "bicycle" encompasses all vehicles with at least two wheels, or at least one wheel and at least one sliding element such as a sled runner, located in a plane or on an axle. A bicycle consists of components. A component is any physical object of the bicycle, and can also be an assembly of components, such as a crankset or an electric drive motor. Rotatable components of a bicycle include, for example, shafts such as a crank axle or a drive shaft, or axles, and similar items.

[0010] The bicycle may have a drive system. The drive system may include at least one crank unit. The crank unit may include at least one crank axle and at least one crank with at least one pedal. Furthermore, the bicycle may have at least one inductive angle sensor for determining the angle of rotation of the crank axle. Power from the rider of the bicycle can be fed into the drive system via the crank unit.

[0011] Additionally, the drive system can include an electric drive motor. An electric drive motor, in this context, refers to any drive system capable of converting electrical power into mechanical power or vice versa, such as DC motors, AC motors, three-phase motors, or similar devices. The bicycle may be equipped with an inductive angle sensor to determine the rotation angle of the electric drive motor's output shaft. The rider's power output can be assisted by the electric drive motor. ZF Friedrichshafen AG File 304854 Friedrichshafen 2023-08-07

[0012] Additionally, the drive system can include a transmission, for example, in the form of a manual transmission or a continuously variable transmission (CVT). The transmission can be shifted automatically via an actuator. Furthermore, the bicycle can include an electrical energy storage device such as batteries, accumulators, capacitors such as supercapacitors, or an energy converter such as a fuel cell with a chemical storage device consisting of a fuel and an oxidizer. The bicycle can also include a steering system, for example, in the form of at least one movable axle connected to at least one wheel or at least one sliding element of the bicycle and to the bicycle frame. The movable axle can, for example, be connected to handlebars. Additionally, the movable axle can be connected to an actuator in the form of an electric motor.This allows the electric motor to assist the rider's steering input on the bicycle. Additionally or alternatively, the movable axle can incorporate an actuator in the form of a centering spring or a steering damper. The centering spring or steering damper can be adjusted according to the rider's cadence. To stabilize the bicycle, the return force of the centering spring or the damping level of the steering damper can be increased. To improve agility, the return force of the centering spring or the damping level of the steering damper can be reduced. Furthermore, the bicycle can be equipped with a brake, which can be a disc brake, a rim brake, or a drum brake. It is also possible to combine the brake with an anti-lock braking system (ABS).Alternatively or additionally, the bicycle can include a brake-by-wire braking system with at least one actuator in the form of an electric servo motor. For example, the braking force can be increased by the actuator below a certain cadence threshold, close to a standstill, to prevent the bicycle from rolling away unintentionally on an incline. The bicycle may also have a damping system with actuators for adjusting the damping level. The damping level can be adjusted depending on the cadence. Furthermore, the bicycle may have an actuator in the form of a human-machine interface, such as a light signal, a sound signal, a screen, or a wearable device (a computer system attached to the human body).

[0013] (can be worn by the body). For example, a bicycle training assistant can use the actuator to inform the rider that they are outside a predefined cadence interval.

[0014] Furthermore, the bicycle can be powered either purely by muscle power, purely electrically, or in hybrid mode by both muscle power and electricity. The bicycle can be, for example, an e-bike, pedelec, e-mountain bike (eMTB), cargo bike, tricycle, quadricycle, or snow bike.

[0015] Inductive rotary angle sensors can be used not only to determine a measured angle of rotation, but also to determine a temporal sequence of measured angles of rotation of a rotating component, such as a crankshaft, a movable axle, the output shaft of an electric drive motor, or the axle of a wheel. A conventional inductive rotary angle sensor typically comprises two opposing elements. Both elements are electromagnetically coupled to each other via an air gap. At least one element is rotatable relative to the other. The fixed, non-rotating element is often called the stator, while the other, rotatable element is often referred to as the rotor.The stator typically comprises at least one excitation loop for generating an alternating magnetic field by applying an alternating voltage or current, and at least one receiver loop for detecting an alternating magnetic field. The rotor comprises a conductor loop for coupling an alternating magnetic field. The excitation loop, the receiver loop, or the rotor's conductor loop can be configured as a coil or a conductor track on a printed circuit board. A primary alternating magnetic field is coupled out via the stator's excitation loop. This primary alternating magnetic field is coupled in via the rotor's conductor loop, whereupon a secondary alternating magnetic field is generated in the rotor's conductor loop and coupled out as a result of induced electric currents.The secondary alternating magnetic field is coupled via the receiver loop, whereupon the receiver loop generates an output signal representing a rotation angle between the stator and the rotor. The air gap between the stator and rotor can have a physical influence on the electromagnetic coupling between the stator and rotor. ZF Friedrichshafen AG File 304854 Friedrichshafen 2023-08-07.

[0016] For example, reducing the distance between the stator and rotor can increase electromagnetic coupling, which can increase the sensitivity of the inductive rotary angle sensor to changes in the air gap. Consequently, a rotation angle measured by an inductive rotary angle sensor can be dependent on the air gap between the stator and rotor. Alternatively, it is possible to place the components of the stator, such as an excitation loop and a receiver loop, on the rotor, and vice versa. Therefore, the stator can include at least one conductor loop, and the rotor can include at least one excitation loop and at least one receiver loop.

[0017] When using an inductive rotary angle sensor to determine the measured rotation angle of a rotating component subjected to high mechanical loads, such as a crank axle, elastic deformation of the crank axle or axial bearing play can lead to a change in the air gap between the two opposing, electromagnetically coupled elements of the inductive rotary angle sensor. Consequently, riding with pedal forces that vary in magnitude, direction, or both over time, particularly during a cyclist's out-of-the-saddle pedaling or a jump, can cause a change in the air gap. Such a change in the air gap can lead to a discrepancy between the mechanical rotation angle of the crank axle and the measured rotation angle. The mechanical rotation angle is defined by the geometry of the rotating component.Since the measured rotation angle can be determined based on a predefined air gap, this predefined air gap may differ from the actual air gap. The deviation resulting from pedal forces varying in magnitude, direction, or both over time between the predefined and actual air gaps can significantly exceed deviations due to manufacturing and assembly tolerances. Furthermore, a large deviation between the predefined and actual air gaps can lead to the measurement of rotation angles that are not physically possible. Such measured rotation angles, which are not physically possible, can vary by several orders of magnitude compared to a mechanical rotation angle and cannot be adequately corrected, for example, using a low-pass filter.This can result in incorrect control or regulation of an electric drive motor or actuator. Therefore, knowledge of the physical characterization of the air gap is necessary to determine the angle of rotation. The physical characterization of the air gap can preferably be achieved using at least one air gap length, which defines the distance between two elements of an inductive rotary angle sensor. The air gap length can be defined from any point on one element of the inductive rotary angle sensor to any point on the other element. For example, this method can also characterize non-ideally cylindrical air gap shapes.

[0018] Furthermore, it is possible to additionally or alternatively characterize the air gap physically, besides its length, using another geometric quantity such as an angle, area, or volume. Additionally or alternatively, it is also possible to characterize the air gap using an electrical physical quantity such as voltage, current, resistance, field strength, flux density, magnetic field strength, magnetic flux density, power, capacitance, or energy transfer.Furthermore, it is also possible to characterize the air gap additionally or alternatively using a radiometric quantity such as transmission power, radiated power, or radiated energy. It is also possible to characterize the air gap additionally or alternatively using a photometric quantity such as luminous intensity or illuminance, or an optical quantity such as a refractive index. Alternatively or additionally, it is possible to characterize the air gap using a flow field. Alternatively or additionally, it is possible to perform the physical characterization of the air gap using one or more of the aforementioned quantities at different times. ZF Friedrichshafen AG File 304854 Friedrichshafen 2023-08-07.

[0019] Determining at least one air gap length between two elements of an inductive rotary angle sensor can be achieved using a distance sensor. The distance sensor can be designed as an inductive distance sensor, a capacitive distance sensor, an optical distance sensor, an ultrasonic distance sensor, a magnetic field distance sensor, or a magnetostrictive distance sensor.

[0020] Alternatively or additionally, it is possible to determine at least one physical characterization of the air gap, for example, in the form of at least one air gap length, using a sensor based on a mutual induction effect. The sensor based on a mutual induction effect can comprise at least one conductor loop. The conductor loop can be implemented as a coil or as a conductor track on a printed circuit board. Furthermore, the conductor loop can be electromagnetically coupled to at least one element of an inductive rotary encoder via an air gap. Consequently, the conductor loop can couple in an alternating magnetic field that is coupled out of one of the two elements of the inductive rotary encoder. Therefore, the air gap between the conductor loop and one of the two elements of the inductive rotary encoder correlates with the air gap between the two elements of the inductive rotary encoder.

[0021] The air gap between the conductor loop and at least one element of the inductive rotary angle sensor can be characterized by at least one air gap length. This air gap length can be defined from any point on the conductor loop to any point on an element of the inductive rotary angle sensor. Furthermore, the air gap length between the conductor loop and at least one element of the inductive rotary angle sensor correlates with the air gap length between the two elements of the inductive rotary angle sensor. Therefore, the air gap between the two elements of the rotary angle sensor can be characterized by at least one air gap length between the conductor loop and at least one element of the inductive rotary angle sensor.

[0022] At least one electrical physical quantity can be measured at the conductor loop. This electrical physical quantity can correlate with the air gap length between the conductor loop and at least one element of the inductive rotary angle sensor. Therefore, at least one physical characterization of the air gap can be determined based on this electrical physical quantity, for example, ZF Friedrichshafen AG File 304854 Friedrichshafen 2023-08-07, using at least one air gap length. The electrical physical quantity can be represented and measured, for example, as at least one electrical voltage, at least one electrical current, or at least one electrical voltage and at least one electrical current.

[0023] Alternatively or additionally, the sensor can be implemented as a transformer based on a mutual induction effect. The transformer can comprise at least one primary conductor loop and at least one opposing secondary conductor loop. The primary conductor loop can be implemented as a coil or as a conductor track on a printed circuit board. The secondary conductor loop can also be implemented as a coil or as a conductor track on a printed circuit board. Furthermore, the primary and secondary conductor loops can be electromagnetically coupled via an air gap. A primary alternating magnetic field can be generated by injecting an alternating voltage or current into the primary conductor loop.A secondary alternating magnetic field can be generated by injecting an alternating electrical voltage or current into the secondary conductor loop. Furthermore, an alternating magnetic field can be coupled in or out, or both, via the primary conductor loop. Similarly, an alternating magnetic field can be coupled in or out, or both, via the secondary conductor loop. Therefore, the primary conductor loop can couple the secondary alternating magnetic field of the secondary conductor loop. Conversely, the secondary conductor loop can couple the primary alternating magnetic field of the primary conductor loop. Consequently, energy transfer, data transfer, or both can occur between the primary and secondary conductor loops.The energy transfer between the primary and secondary conductor loops can be configured. This energy transfer, data transfer, or both can be based on Near Field Communication (NFC) or Radio-Frequency Identification (RFID) technology. ZF Friedrichshafen AG File 304854 Friedrichshafen 2023-08-07.

[0024] The air gap between the primary and secondary conductor loops can be characterized by at least one air gap length. This air gap length can be defined from any point on the primary conductor loop to any point on the secondary conductor loop. The air gap between the primary and secondary conductor loops can correlate with the air gap between the two elements of the inductive rotary angle sensor. Consequently, the air gap length between the primary and secondary conductor loops correlates with the air gap length between the two elements of the inductive rotary angle sensor. Therefore, the air gap between the two elements of the rotary angle sensor can be characterized by at least one air gap length between the primary and secondary conductor loops.

[0025] Alternatively or additionally, the primary or secondary conductor loop can be electromagnetically coupled to at least one element of an inductive rotary encoder via an air gap. This air gap can correlate with the air gap between the two elements of the inductive rotary encoder. Furthermore, this air gap can be characterized by its length. The air gap length can be defined from any point on the primary or secondary conductor loop to any point on at least one element of the inductive rotary encoder. Consequently, the air gap between two elements of an inductive rotary encoder can be characterized by the air gap length between the primary or secondary conductor loop and an element of the inductive rotary encoder.

[0026] At least one electrical physical quantity can be measured at the primary conductor loop, the secondary conductor loop, or both the primary and secondary conductor loops. This electrical physical quantity can correlate with at least one physical characterization of the air gap, for example, by means of at least one air gap length between the primary and secondary conductor loops. Alternatively or additionally, the electrical physical quantity can correlate with at least one physical characterization of the air gap, for example, by means of at least one air gap length between the primary or secondary conductor loop and at least one element of an inductive rotary angle sensor. [The electrical physical quantity is not part of the document.] ZF Friedrichshafen AG File 304854 Friedrichshafen 2023-08-07

[0027] Quantity can be represented and measured as an electrical voltage or an electrical current, or as an electrical voltage and an electrical current.

[0028] The distance sensor, the sensor based on a mutual induction effect, or both the distance sensor and the sensor based on a mutual induction effect may be integrated into the inductive rotary angle sensor or into an element of the inductive rotary angle sensor, or they may be located outside the rotary angle sensor as an external unit. At least one conductor loop of the sensor based on a mutual induction effect may be integrated into at least one of the two elements of the inductive rotary angle sensor or be located outside the inductive rotary angle sensor.

[0029] The method for determining the angle of rotation of a rotatable component of bicycles can be performed during a rotation of the rotatable component or during a standstill of the rotatable component.

[0030] In a first step of the process, at least one current physical characterization of an air gap is determined, for example, in the form of at least one current air gap length using at least one distance sensor, or using at least one sensor based on the effect of mutual induction, or using at least one distance sensor and at least one sensor based on the effect of mutual induction. If a current physical characterization is determined using a sensor based on the effect of mutual induction, the physical characterization can, for example, be in the form of power transfer in at least one conductor loop of the sensor based on the effect of mutual induction. Additionally, at least one measured rotation angle of the rotatable component, such as a crank axle, is recorded using an inductive angle sensor.The measured rotation angle can correlate with the mechanical rotation angle. Alternatively or additionally, it is possible to measure other physical quantities that correlate with the measured rotation angle and the mechanical rotation angle. Furthermore, it is possible (ZF Friedrichshafen AG File 304854 Friedrichshafen 2023-08-07) to determine at least one further physical quantity, such as temperature, using at least one additional sensor.

[0031] In a subsequent second step, previously stored data is retrieved from a data storage device. This data can be stored, for example, during the initial setup of the rotary angle sensor. The data can be generated based on a defined variation of the air gap and a corresponding measured rotation angle. The data storage device can be a non-volatile semiconductor memory, such as a read-only memory (ROM) in the form of an electrically erasable programmable read-only memory (EEPROM), or a flash memory in the form of a NAND flash memory. From the data, at least one physical influence of the air gap can be determined, depending on the established physical characteristics of the air gap.It is possible to determine the physical influence of the air gap as a function of the measured rotation angle. It is also possible to determine the physical influence of the air gap as a function of at least one other physical quantity, such as temperature. The data can be presented as at least one interpolation table for an interpolation method. Alternatively or additionally, the data can preferably be presented as at least one parameter value for a mathematical function. The interpolation method can include, for example, piecewise constant interpolation, linear interpolation, an interpolation polynomial, or Gaussian regression.The mathematical function can, for example, comprise a regression polynomial, a generalized Fourier series, a semi-physical model, or a regression model such as an artificial neural network, a radial basis function network, or a Gaussian process. In a third step of the procedure, at least one correction value is determined using the interpolation table and the interpolation method, or using the parameter value and the mathematical function, or using the interpolation table and the interpolation method and the parameter value and the mathematical function. The correction value quantifies the physical influence of the air gap. The correction value can be derived from the determined physical ZF Friedrichshafen AG File 304854 Friedrichshafen 2023-08-07.

[0032] Characterization of the air gap and optionally dependent on the measured rotation angle and optionally on at least one other physical quantity such as temperature.

[0033] In a fourth step of the process, a rotation angle is determined by correcting the measured rotation angle using the correction value. Alternatively or additionally, another measured physical quantity can be determined by correcting it using the correction value. This other measured physical quantity, or the corrected measured quantity, can correlate with the measured rotation angle and the mechanical rotation angle. In a fifth step, the determined rotation angle and a timestamp are stored in a buffer. The timestamp can be a relative or absolute time. Consequently, a chronological sequence of determined rotation angles is stored in the buffer.The intermediate memory can be implemented, for example, as a volatile semiconductor memory such as random-access memory (RAM) in the variant of static random-access memory (SRAM) or dynamic random-access memory (DRAM). In a sixth step, the intermediate memory is checked. If a previously defined minimum number of determined rotation angles in the intermediate memory is exceeded, a seventh step of the procedure follows. Otherwise, the procedure is terminated. In the seventh step of the procedure, at least one derived physical quantity, such as an angular velocity, is determined from the temporal sequence of the determined rotation angles in the intermediate memory. If the rotating component is a crank axle, the crank axle's cadence is determined alternatively or additionally.In an eighth step of the process, if the rotatable component is a crankshaft, the derived physical quantity, such as the angular velocity or cadence of a crankshaft, is used to control or regulate an electric drive motor or actuator of a bicycle, or both an electric drive motor and an actuator of a bicycle. For example, it is possible to control or regulate an electric drive motor or actuator using at least one predefined control parameter or regulation parameter, depending on the derived physical quantity (ZF Friedrichshafen AG File 304854 Friedrichshafen 2023-08-07). It is also possible, for example, to compare the cadence of a crankshaft with a predefined threshold value.Based on the comparison between the cadence of the pedal shaft and the threshold value, as well as the direction of rotation of the pedal shaft, it can be determined whether pedaling is in a forward or reverse direction. For example, when pedaling in a forward direction, the electric drive motor can be controlled with a target torque. The process ends after the eighth step is completed.

[0034] A control unit for a bicycle can be effectively connected to at least one inductive rotation angle sensor of the bicycle. Additionally, the control unit can be effectively connected to a distance sensor, a sensor based on a mutual induction effect, or a distance sensor and a sensor based on a mutual induction effect. The control unit can also be effectively connected to an electric drive motor of the bicycle, an actuator of the bicycle, or an electric drive motor of the bicycle and an actuator of the bicycle.

[0035] The control unit comprises means for carrying out the method according to the invention. The control unit can, for example, be designed as a control device (electronic control unit or electronic control module).

[0036] When the control unit is used in or outside of a bicycle, it is effectively connected to at least one inductive angle sensor. Additionally, the control unit is effectively connected to at least one distance sensor, or a sensor based on a mutual induction effect, or a distance sensor and a sensor based on a mutual induction effect.

[0037] A signal-effective connection is such that data and signal exchange between the connection partners is possible. For this purpose, each connection partner has a corresponding interface. Data transmission and signal transmission can be either wired or wireless. The control unit and the inductive rotary angle sensor and the distance sensor, or the sensor based on a counter-induction effect, or the distance sensor and the sensor based on a counter-induction effect, therefore have interfaces that enable such a connection. The control unit and ZF Friedrichshafen AG File 304854 Friedrichshafen 2023-08-07, the electric drive motor, or the actuator, or the electric drive motor and the actuator, therefore have interfaces that enable a signal-effective connection.Furthermore, the control unit can be configured to control or regulate the electric drive motor or the actuator, or both. The control unit can also be configured to send predefined control parameters to the electric drive motor for controlling the motor, or predefined control parameters to regulate the motor. Additionally, the control unit can be configured to send predefined control parameters to the actuator for controlling the motor, or predefined control parameters of the actuator to the actuator. The control unit can be integrated into a housing together with the electric drive motor or the actuator. The housing can be mechanically connected to the bicycle frame, for example, to the bicycle's downtube.

[0038] A computer program product comprises instructions which, when the program is executed by the control device already described, cause it to execute the procedure already described.

[0039] A computer-readable medium comprises instructions that, when executed by the control device described above, cause it to perform the procedure already described. The computer-readable medium can, for example, be in the form of a data carrier or a downloadable data stream.

[0040] Exemplary embodiments of the invention are shown in the figures. Specifically, they show:

[0041] Fig. 1 shows a schematic representation of a bicycle according to one embodiment.

[0042] Fig. 2 is a schematic representation of an inductive rotation angle sensor of the bicycle 1 from Fig. 1 with an integrated sensor based on the effect of mutual induction in the form of a conductor loop. ZF Friedrichshafen AG File 304854 Friedrichshafen 2023-08-07

[0043] Fig. 3 is a schematic representation of an inductive rotation angle sensor of the bicycle 1 from Fig. 1 with an integrated sensor based on the effect of mutual induction in the form of a transformer.

[0044] Fig. 4 shows a step of the procedure for determining the angle of rotation of a pedal crank shaft 4 from Fig. 1 of the bicycle 1 from Fig. 1. Fig. 5 shows an alternative step of the procedure for determining the angle of rotation of a pedal crank shaft 4 from Fig. 1 of the bicycle 1 from Fig. 1.

[0045] Fig. 1 shows a schematic representation of a bicycle 1 according to an exemplary embodiment. The bicycle 1 is designed as an e-bike or pedelec, or in particular as an e-mountain bike. The bicycle 1 has a drive system 2. The drive system 2 comprises an electric drive motor E, a crank unit 3, and an inductive angle sensor DW. The inductive angle sensor DW has an integrated sensor based on a back-induction effect, which serves to determine a physical characterization of an air gap in the inductive angle sensor DW. The crank unit 3 comprises at least one crank shaft 4, at least one crank arm 5, and at least one pedal 6. The angle of rotation of the crank shaft 4 is measured by means of the inductive angle sensor DW. In addition, the drive system 2 has a gearbox with an actuator A for automated gear shifting.The electric drive motor E, the pedal crank unit 3 and the gearbox with the actuator A can be located in the area of ​​the bottom bracket.

[0046] Furthermore, the drive system 2 includes an electrical energy storage device 7, which is connected to the electric drive motor E. Additionally, the electrical energy storage device 7 can also supply the electric drive motor E with electrical energy (motor operation) or can be supplied with electrical energy by the electric drive motor E (generator operation). The bicycle 1 can therefore be driven either purely by muscle power, purely electrically, or by both muscle power and electrically. The drive system 2, the electrical energy storage device 7, and the inductive rotation angle sensor DW are connected to a control unit EC of the bicycle 1. ZF Friedrichshafen AG File 304854 Friedrichshafen 2023-08-07

[0047] Furthermore, bicycle 1 has a steering system consisting of a movable axle 8 and a handlebar 9. The movable axle 8 is connected to the bicycle frame of bicycle 1, as well as to the handlebar 9 and a front wheel 11 of bicycle 1. The movable axle 8 can be rotated about its rotationally symmetrical axis by means of the handlebar 9, thereby steering the front wheel 11. Additionally, bicycle 1 has an inductive rotary angle sensor ZDW for detecting the rotation angle of the movable axle 8. The additional inductive rotary angle sensor ZDW is connected to the control unit EC via a signal. The rotation angle of the movable axle 8 can be used to control a turn signal. Furthermore, bicycle 1 has a brake 10, which can be, for example, a disc brake, a rim brake, or a drum brake.Additionally, it is possible to combine a brake with an anti-lock braking system. By actuating the brake 10, the rotation of a rear wheel 12 can be reduced or prevented. The brake 10 is connected to the EC control unit via a signal.

[0048] Fig. 2 shows a schematic representation of an inductive rotary angle sensor DW of the bicycle 1 from Fig. 1 with an integrated sensor based on the effect of mutual induction S in the form of a conductor loop LA. The inductive rotary angle sensor DW has an element E1 and an opposing element E2. The elements E1 and E2 are separated by an air gap LT. The air gap LT can be described by a physical characterization L or an alternative physical characterization LALT, or by the physical characterization L and the alternative physical characterization LALT. The element E1 can also be called the stator, whereas the element E2 is called the rotor. The element E2 can rotate relative to the element E1.Element E1 comprises an excitation coil L1 for generating an alternating magnetic field, a receiver coil L2 for coupling an alternating magnetic field, and a conductor loop LA for coupling an alternating magnetic field. Element E2 comprises a coil L3 in which an alternating magnetic field can be coupled in and out. A primary alternating magnetic field PFS can be coupled out via the excitation coil L1. The primary alternating magnetic field PFS is coupled in via the coil L3, whereupon a secondary alternating magnetic field SFS is generated in the coil L3 and coupled out as a result of induced electric currents. The secondary alternating magnetic field SFS is coupled in via the receiver coil L2, whereupon the receiver coil L2 generates an output signal that represents a measured rotation angle Ds between element E1 and element E2.The physical characterization L of the air gap LT, or the alternative physical characterization LALT of the air gap LT, or both the physical characterization L of the air gap LT and the alternative physical characterization LALT of the air gap LT, can be determined via the coil L3 and the conductor loop LA. The physical characterization L of the air gap LT, or the alternative physical characterization LALT of the air gap LT, or both the physical characterization L of the air gap LT and the alternative physical characterization LALT of the air gap LT, can be determined by applying an electric current SK, an electric voltage SP, or both an electric current SK and an electric voltage SP to the conductor loop LA.The electric current SK and electric voltage SP correlate with the physical characterization L of the air gap LT, or the alternative physical characterization LALT of the air gap LT, or the physical characterization L of the air gap LT and the alternative physical characterization LALT of the air gap LT. Based on the electric voltage SP, the electric current SK, or the electric voltage SP and the electric current SK, at least one air gap length between element E1 and element E2 can be determined. However, instead of the air gap length, the electric voltage SP, the electric current SK, or the electric voltage SP and the electric current SK can also be used directly. This allows, for example, the determination of a quantified physical influence of the air gap LT in the form of a correction value.The correction value can be determined as a function of the electrical voltage SP or the electrical current SK, or of both the electrical voltage SP and the electrical current SK. Additionally, it is possible to determine the correction value as a function of a measured rotation angle. ZF Friedrichshafen AG File 304854 Friedrichshafen 2023-08-07.

[0049] Fig. 3 shows a schematic representation of an inductive rotation angle sensor DW of the bicycle 1 from Fig. 1 with an integrated sensor based on the effect of a mutual induction S in the form of a transformer.

[0050] The inductive rotary angle sensor DW, like the inductive rotary angle sensor DW from Fig. 3, also comprises an element E1 with an excitation coil L1 and a receiver coil L2, as well as an element E2 with a coil L3. Elements E1 and E2 are separated by an air gap LT. The air gap LT can be described by a physical characterization L or an alternative physical characterization LALT. A primary alternating magnetic field PFS can be coupled out via the excitation coil L1. The primary alternating magnetic field PFS can be coupled in via the coil L3. A secondary alternating magnetic field SFS is coupled out of the coil L3 and coupled in via the receiver coil L2, which generates an output signal representing a measured rotation angle between element E1 and element E2.

[0051] The transformer has a primary conductor loop LP and a secondary conductor loop LS. The primary conductor loop LP and the secondary conductor loop LS are separated by the air gap LT. The primary conductor loop LP can be formed as a coil and the secondary conductor loop LS can be formed as a conductor track on a printed circuit board.

[0052] An alternating voltage WS1 or an alternating current can be applied to the primary conductor loop LP, thereby generating and coupling out a primary alternating magnetic field PF. The primary alternating magnetic field PF can then be coupled in via the secondary conductor loop LS.

[0053] Energy transfer, data transfer, or both can occur between the primary conductor loop LP and the secondary conductor loop LS. An electric current SK1 and an electric voltage SP1 can be measured at the primary conductor loop LP.

[0054] An alternating voltage WS2 or an alternating current can be applied to the secondary conductor loop LS, thereby generating and coupling out a secondary alternating magnetic field SF. The secondary alternating magnetic field SF can be coupled in via the primary conductor loop LP (ZF Friedrichshafen AG File 304854 Friedrichshafen 2023-08-07). Energy transfer, data transfer, or both can occur between the secondary conductor loop LS and the primary conductor loop LP. An electric current SK2 and an electric voltage SP2 can be measured at the secondary conductor loop LS.

[0055] The transmit power of the primary conductor loop LP can be determined using the electrical voltage SP1 and the electrical current SK1. The received transmit power can be determined using the electrical voltage SP2 and the electrical current SK2 at the secondary conductor loop LS.

[0056] The transmit power of the secondary conductor loop LS can be determined from the electrical voltage SP2 and electrical current SK2. The received transmit power can be determined using the electrical voltage SP1 and the electrical current SK1 at the primary conductor loop LP.

[0057] The physical characterization L of the air gap LT or the alternative physical characterization LALT of the air gap LT or the physical characterization L of the air gap LT and the alternative physical characterization LALT of the air gap LT correlates with the received transmit power at the primary conductor loop LP and the received transmit power at the secondary conductor loop LS.

[0058] Consequently, the physical characterization L of the air gap LT or the alternative physical characterization LALT of the air gap LT or the physical characterization L of the air gap LT and the alternative physical characterization LALT of the air gap LT can be described by means of the received transmit power at the primary conductor loop LP or the received transmit power at the secondary conductor loop LS or the received transmit power at the primary conductor loop LP and the received transmit power at the secondary conductor loop LS or a combination of the electrical voltage SP1, the electrical current SK1, the electrical voltage SP2 and the electrical current SK2.Furthermore, based on the received transmit power at the primary conductor loop LP or the received transmit power at the secondary conductor loop LS or the received transmit power at the primary conductor loop LP and the received transmit power at the secondary conductor loop LS or a combination of the electrical voltage SP1, the electrical current SK1, the electrical voltage SP2 and the electrical current SK2, at least one air gap length between the element E1 and the element E2 can be determined.

[0059] Instead of the air gap length, the received transmit power at the primary conductor loop LP or the received transmit power at the secondary conductor loop LS or the received transmit power at the primary conductor loop LP and the received transmit power at the secondary conductor loop LS or a combination of the electrical voltage SP1, the electrical current SK1, the electrical voltage SP2 and the electrical current SK2 can also be used to determine a quantified physical influence of the air gap LT in the form of a correction value.The correction value can be determined as a function of the received transmit power at the primary conductor loop LP, or the received transmit power at the secondary conductor loop LS, or the received transmit power at both the primary conductor loop LP and the secondary conductor loop LS, or a combination of the electrical voltage SP1, the electrical current SK1, the electrical voltage SP2, and the electrical current SK2. Additionally, it is possible to determine the correction value as a function of a measured rotation angle.

[0060] Fig. 4 shows a diagram of the process 100 for determining a rotation angle D* of a crank axle 4 of the bicycle 1 from Fig. 1. In a first step 101, a current physical characterization L of an air gap LT of an inductive rotary angle sensor DW, as shown in Fig. 3 or Fig. 4, is determined. Additionally, a measured rotation angle Ds is recorded using the inductive rotary angle sensor DW from Fig. 3 or Fig. 4. In a second step 102, data DAT is retrieved from a data storage device STO. From the data, at least one physical influence of the air gap LT can be determined as a function of at least one physical characterization L of the air gap LT of the rotary angle sensor DW from Fig. 3 or Fig. 4, for example, in the form of an air gap length. The data is preferably expressed as at least one parameter value for a polynomial function.In a third step 103 of the procedure, a correction value K is determined using the parameter value and the polynomial function. In the fourth step 104, a correction of the measured rotation angle Ds is applied. ZF Friedrichshafen AG File 304854 Friedrichshafen 2023-08-07.

[0061] The correction value K is applied, resulting in a determined rotation angle D*. In the fifth step 105, the determined rotation angle D* and a timestamp are stored in a buffer BFF. From at least two determined rotation angles D* and their corresponding timestamps, a temporal sequence of determined rotation angles D* can be determined. In the sixth step 106, it is checked whether the number of rotation angles iD* of the determined rotation angles D* exceeds a previously defined number n. If the number of rotation angles iD* exceeds the previously defined number n, the procedure 100 is continued in the seventh step 107. Otherwise, the procedure 100 is terminated. In the seventh step 107, an angular velocity O of the crank axle 4 of the bicycle 1 from Fig. 1 and a cadence F of the crank axle 4 of the bicycle 1 from Fig. 1 are determined from the temporal sequence of the determined rotation angles D*.The determined angular velocity O and determined cadence F are used in an eighth step 108 to control or regulate the electric drive motor E of the bicycle 1 from Fig. 1 and to control or regulate a gearbox via the actuator A of the bicycle 1 from Fig. 1. The procedure 100 is then terminated.

[0062] Fig. 5 shows an alternative version of method 100 for determining the rotation angle D* of a crank axle 4 of the bicycle 1 from Fig. 1. Method steps 101, 104, 105, 106, 107, and 108 are identical to the corresponding method steps in Fig. 4. In an alternative step 112 of method 100, data DAT is retrieved from a data storage device STO. From this data, at least one physical influence of the air gap LT can be determined as a function of at least one physical characterization L of the air gap LT of the rotation angle sensor DW from Fig. 3 or Fig. 4, for example, in the form of an air gap length, and as a function of the measured rotation angle Ds. The data is preferably presented as at least one interpolation table for linear interpolation. In a third step 103 of the method, a correction value K is determined using the interpolation tables and the linear interpolation.ZF Friedrichshafen AG File 304854 Friedrichshafen 2023-08-07.

[0063] Reference mark

[0064] 1 bicycle

[0065] 2 Drive system

[0066] 3 Crank unit

[0067] 4. Crankshaft

[0068] 5 Crankset

[0069] 6 pedal

[0070] 7 electrical energy storage

[0071] 8 movable axes

[0072] 9 Steering wheel

[0073] 10 Brake

[0074] 11 front wheel

[0075] 12 rear wheel

[0076] 100 procedures

[0077] 101 First Step

[0078] 102 second step

[0079] 103 third step

[0080] 104 fourth step

[0081] 105 fifth step

[0082] 106 sixth step

[0083] 107 seventh step

[0084] 108 eighth step

[0085] 112 alternative second step

[0086] 113 alternative third step

[0087] E electric drive motor

[0088] A actuator

[0089] EC control unit

[0090] DW inductive rotation angle sensor

[0091] ZDW additional inductive rotary angle sensor

[0092] Start of procedure

[0093] End of procedure

[0094] STO Data Storage ZF Friedrichshafen AG File 304854 Friedrichshafen 2023-08-07

[0095] BFF cache

[0096] 0 angular velocity

[0097] F cadence

[0098] PF primary alternating magnetic field

[0099] PFS primary magnetic alternating field

[0100] SF secondary alternating magnetic field

[0101] SFS secondary magnetic alternating field

[0102] K correction value

[0103] The measured angle of rotation

[0104] D* determined rotation angle

[0105] L physical characterization

[0106] LT air gap iD number of rotation angles n defined number

[0107] LALT alternative physical characterization

[0108] E1 Element of an inductive rotary angle sensor

[0109] E2 Element of an inductive rotary angle sensor

[0110] L1 Excitation coil

[0111] L2 receiver coil

[0112] L3 coil

[0113] LA conductor loop

[0114] S sensor based on a counter-induction effect

[0115] SK electric current

[0116] SP electrical voltage

[0117] SK1 electric current

[0118] SP1 electrical voltage

[0119] SK2 electric current

[0120] SP2 electrical voltage

[0121] WS1 alternating current

[0122] WS2 alternating current

[0123] LP primary conductor loop

[0124] LS secondary conductor loop

Claims

ZF Friedrichshafen AG File 304854 Friedrichshafen 2023-08-07 Patent claims 1. Method for determining a rotation angle (D*) of a rotatable component of a bicycle (1) with at least one inductive rotation angle sensor (DW), wherein the inductive rotation angle sensor (DW) comprises at least two opposing elements (E1, E2), wherein the two elements (E1, E2) of the inductive rotation angle sensor (DW) are electromagnetically coupled via an air gap (LT), characterized in that a physical characterization (L) of the air gap (LT) between the two elements (E1, E2) of the inductive rotation angle sensor (DW) is sensorially determined and, depending on the determined physical characterization (L) of the air gap (LT), at least one previously quantified physical influence of the air gap (LT) serves to determine the rotation angle (D*).

2. Method according to claim 1, characterized in that the physical characterization (L) of the air gap (LT) between the two elements (E1, E2) of the inductive rotary angle sensor (DW) is carried out using at least one air gap length, wherein the air gap length is determined by means of at least one distance sensor or a sensor based on a counter-induction effect (S) or a distance sensor and a sensor based on a counter-induction effect (S).

3. Method according to claim 2, characterized in that the distance sensor can be implemented as an inductive distance sensor, a capacitive distance sensor, an optical distance sensor, an ultrasonic distance sensor, a magnetic field distance sensor, or a magnetostrictive distance sensor, wherein the distance sensor or the sensor based on a counter-induction effect (S), or the distance sensor and the sensor based on a counter-induction effect (S), can be integrated into the inductive rotary angle sensor (DW) or into an element (E1, E2) of the inductive rotary angle sensor (DW). ZF Friedrichshafen AG File 304854 Friedrichshafen 2023-08-07 4. Method according to claim 2 or 3, characterized in that the sensor, based on an effect of mutual induction (S), comprises at least one conductor loop (LA), wherein the conductor loop (LA) is electromagnetically coupled to at least one element (E1, E2) of the inductive rotary angle sensor (DW) via an air gap (LT), wherein the air gap (LT) between the conductor loop (LA) and an element (E1, E2) of the inductive rotary angle sensor (DW) is characterized by at least one air gap length, wherein the air gap length between the conductor loop (LA) and an element (E1, E2) of the inductive rotary angle sensor (DW) correlates with the air gap length between the two elements (E1, E2) of the inductive rotary angle sensor (DW).

5. Method according to claim 4, characterized in that at least one electrical physical quantity can be measured at the conductor loop (LA), wherein the electrical physical quantity can be represented as at least one electrical voltage (SP) or at least one electrical current (SK) or at least one electrical voltage (SP) and at least one electrical current (SK), wherein the electrical physical quantity correlates with the air gap length between the conductor loop (LA) and an element (E1, E2) of the inductive rotary angle sensor (DW), wherein the electrical physical quantity correlates with at least one physical characterization (L) of the air gap (LT) between the conductor loop (LA) and an element (E1, E2) of the inductive rotary angle sensor (DW).

6. Method according to claim 2 or 3, characterized in that the sensor based on a mutual induction (S) effect can be implemented as at least one transformer, wherein the transformer comprises at least one primary conductor loop (LP) and at least one opposing secondary conductor loop (LS), wherein the primary conductor loop (LP) and the secondary conductor loop (LS) are electromagnetically coupled via an air gap (LT), wherein the air gap (LT) between the primary conductor loop (LP) and the secondary conductor loop (LS) can be characterized by at least one air gap length, wherein the air gap length between the primary conductor loop (LP) and the secondary conductor loop (LS) correlates with the air gap length between the two elements (E1, E2) of the inductive rotary angle sensor (DW). ZF Friedrichshafen AG File 304854 Friedrichshafen 2023-08-07 7. Method according to claim 6, characterized in that a primary alternating magnetic field (PF) can be generated by supplying an alternating electrical voltage (WS1) or an alternating electrical current into the primary conductor loop (LP), wherein a secondary alternating magnetic field (SF) can be generated by supplying an alternating electrical voltage (WS2) or an alternating electrical current into the secondary conductor loop (LS), wherein energy transfer or data transfer or energy transfer and data transfer from the primary conductor loop (LP) to the secondary conductor loop (LS) or from the secondary conductor loop (LS) to the primary conductor loop (LP) or from the primary conductor loop (LP) to the secondary conductor loop (LS) and from the secondary conductor loop (LS) to the primary conductor loop (LP) is possible.

8. Method according to claim 6 or 7, characterized in that an electrical physical quantity is measurable at the primary conductor loop (LP) or the secondary conductor loop (LS) or the primary conductor loop (LP) and secondary conductor loop (LS), wherein the electrical physical quantity can be represented as an electrical voltage (SP1, SP2) or an electrical current (SK1, SK2) or an electrical voltage (SP1, SP2) and an electrical current (SK1, SK2), wherein the electrical physical quantity correlates with the air gap length between the primary conductor loop (LP) and the secondary conductor loop (LS), wherein the electrical physical quantity correlates with at least one physical characterization (L) of the air gap (LT) between the primary conductor loop (LP) and the secondary conductor loop (LS).

9. Method according to claim 1 or 2, characterized in that the physical influence of the air gap (LT) is quantified in the form of at least one correction value (K) from previously stored data (DAT) from at least one data storage device (STO), wherein the physical influence of the air gap (LT) and the correction value (K) depend on the determined physical characterization (L) of the air gap (LT) or the determined physical characterization (L) of the air gap (LT) and at least one measured rotation angle (Ds) or the physical characterization (L) of the air gap (LT) and at least one ZF Friedrichshafen AG File 304854 Friedrichshafen 2023-08-07 measured rotation angle (Ds) and at least one other physical quantity is determined, whereby the determined rotation angle (D*) is determined using the correction value (K).

10. Method according to claim 1 or 9, characterized in that the determined rotation angle (D*) or at least one derived physical quantity of the determined rotation angle (D*) or the determined rotation angle (D*) and at least one derived physical quantity of the determined rotation angle (D*) is used to control or regulate at least one electric drive motor (E) of the bicycle (1 ) or at least one actuator (A) of the bicycle (1 ) or at least one electric drive motor (E) of the bicycle (1 ) and at least one actuator (A) of the bicycle (1 ).

11. Method according to claim 10, characterized in that, for controlling or regulating the electric drive motor (E) of the bicycle (1 ) or the actuator (A) of the bicycle (1 ) or the electric drive motor (E) of the bicycle (1 ) and the actuator (A) of the bicycle (1 ), an angular velocity (O) of a pedal crank shaft (4) of the bicycle or a cadence (F) of a pedal crank shaft (4) of the bicycle (1 ) or an angular velocity (O) of a pedal crank shaft (4) of the bicycle (1 ) and a cadence (F) of a pedal crank shaft (4) of the bicycle (1 ) is determined from a temporal sequence of determined rotation angles (D*) of a pedal crank shaft (4) of the bicycle (1 ).

12. Control device (EC) for a bicycle (1) , characterized in that at least one inductive rotation angle sensor (DW) of the bicycle (1) and at least one distance sensor or a sensor based on a counter-induction effect (S) or at least one distance sensor and a sensor based on a counter-induction effect (S) can be effectively connected to the control device (EC) via a signal, and wherein the control device (EC) comprises means for carrying out the method (100) according to one of claims 1 to 11. ZF Friedrichshafen AG File 304854 Friedrichshafen 2023-08-07 13. Computer program product comprising instructions which, when the program is executed by a control device (EC), cause the method (100) according to any one of claims 1 to 11 to be executed.

14. Computer-readable medium comprising instructions which, when executed by a control device (EC), cause it to execute the method (100) according to any one of claims 1 to 11.

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