System and method for determining an absolute pedal crank angle

Abstract

The invention relates to a system and a method for determining an absolute pedal crank angle of a vehicle (1) that is at least partially propelled by muscle power, wherein, when starting off, local extreme points are determined from signal data on the angle change of a pedal crank shaft (2) using mathematical functions, wherein four local extreme points form one total crank revolution, wherein a first local maximum is determined as a 90° pedal crank angle, and wherein the subsequent extreme points are determined as a 180° pedal crank angle, a 270° pedal crank angle and a 360° pedal crank angle.Furthermore, the invention relates to a system and a method for determining an absolute pedal crank angle of a vehicle (1) that is at least partially propelled by muscle power, wherein, at a constant cadence, local extreme points are determined from signal data on the angle change of a pedal crank shaft (2) using mathematical functions, wherein four local extreme points form one total crank revolution and a global maximum of the total crank revolution is determined as a 90° pedal crank angle, wherein the subsequent extreme points are determined as 180° pedal crank angle, 270° pedal crank angle and 360° pedal crank angle.

Description

[0001] The invention relates to a system and a method for determining the absolute pedal crank angle of a vehicle that is at least partially propelled by muscle power. Furthermore, the invention also relates to a vehicle that is at least partially propelled by the muscle power of a driver and includes such a system.

[0002] For example, DE 10 2020 215 569 A1 discloses a control method for an electric bicycle with an electric motor as the drive motor. The method comprises the following steps: detecting the rotational speed of the pedal axle, detecting the pedaling force applied by the rider, determining the rider's power output as a function of the detected rotational speed and the detected pedaling force, determining a power deviation between the determined rider's power output and a power setpoint, and controlling the electric motor to generate motor torque as a function of the determined power deviation, wherein, if the detected rider power output is less than the power setpoint, the generated motor power is increased with increasing power deviation.

[0003] From WO 2023 / 195 276 A1, an engine control device for an electrically assisted vehicle and an electrically assisted vehicle itself are known. The engine control is designed to recover energy during braking. It uses certain conditions relating to the position and speed of the crankshaft to determine when regenerative braking should be activated, thus ensuring smoother transitions and better control.

[0004] Publication DE 10 2014 208 479 A1 relates to a gearshift for a bicycle with an electric auxiliary drive, comprising a stepped transmission designed as a hub gear or derailleur gear and an electromechanical actuator for triggering a gear change of the transmission.

[0005] The object of the invention is to create an alternative system, vehicle, and method for operating a vehicle that is at least partially powered by muscle power. This object is achieved by the subject matter of claims 1, 2, 6, 7, and 8. Preferred embodiments are described in the dependent claims, the description, and the figures.

[0006] A system according to the invention for determining an absolute pedal crank angle of a vehicle that is at least partially propelled by muscle power comprises a pedal crank shaft which is configured to be connected to pedals via pedal cranks, a sensor system for detecting a change in the angle of the pedal crank shaft and a data processing device which is configured to be connected to the sensor system via signal transmission in order to determine local extreme points from signal data from the sensor system regarding the change in the angle of the pedal crank shaft using mathematical functions when starting off, wherein four local extreme points constitute one total crank revolution and a first local maximum is determined as a 90° pedal crank angle, wherein the subsequent extreme points are determined as a 180° pedal crank angle, a 270° pedal crank angle and a 360° pedal crank angle.The extrema of a mathematical function can be determined by differentiating the function and occur as minima (or local lows) and maxima (or local highs). A maximum occurs when the first derivative of the function is zero and the second derivative is less than zero. A minimum occurs when the first derivative of the function is zero and the second derivative is greater than zero.

[0007] An alternative system according to the invention for determining the absolute pedal crank angle of a vehicle that is at least partially propelled by muscle power comprises a pedal crank shaft configured to be connected to pedals via pedal cranks, a sensor for detecting changes in the angle of the pedal crank shaft, and a data processing device configured to be connected to the sensor for signal transmission. At a substantially constant vehicle speed, the system uses mathematical functions to determine local extreme points from signal data from the sensor regarding the angle of change of the pedal crank shaft. Four local extreme points constitute one total crank revolution, and a global maximum of the total crank revolution is determined as a 90° pedal crank angle. Subsequent extreme points are determined as 180°, 270°, and 360° pedal crank angles. The two systems can be combined.

[0008] Thus, both systems are designed to determine local extreme points using mathematical functions. The first system is used during acceleration, while the second is used at a substantially constant vehicle speed, particularly at a substantially constant cadence of the rider. In both cases, the mathematical function for the change in angle of the crank arm or for the angular velocity of the crank arm is, in a highly simplified form, a modified sine function. This is because the rider generates a rotational irregularity while pedaling, as the maximum lever arm for applying force to the pedals occurs at crank arm angles of 90° and 270°, and the lever arm is minimal at crank arm angles of 180°, 360°, and 0°, respectively.Furthermore, the rider typically has legs of different strength, with the stronger leg capable of applying greater torque to the crank arm, resulting in a larger change in angle. This creates, at a substantially constant cadence, not only local extremes but also a global extreme point, namely a global maximum, for each total crank revolution. Starting off is usually also done with the stronger leg, so the first extreme point in the mathematical function is a local maximum. Four local extreme points constitute one total crank revolution, with local maxima (high points) and local minima (low points) alternating. Thus, local maxima occur at crank arm angles of 90° and 270°, where the crank arms are horizontally oriented. Local minima occur at crank arm angles of 180°, 360°, and 0°, respectively, where the crank arms are vertically oriented.The sensor system for detecting angle changes includes at least one rotation angle sensor. Preferably, the rotation angle sensor detects a change in the rotation angle of the crank arm and generates signal data that is provided to the data processing device. The rotation angle sensor cannot detect absolute rotation angles of the crank arm.

[0009] According to one embodiment, the system comprises a generator with a rotor and a stator, wherein the generator's rotor is fixedly connected to the pedal crank shaft. Thus, the generator is designed as a pedal generator and converts the kinetic energy introduced by the rider via the pedals into electrical energy. The harder the rider pedals and the greater the resistance of the generator, the greater the electrical power generated by the generator.

[0010] According to one embodiment, the system comprises an electric motor with a rotor and a stator, wherein the rotor of the electric motor is configured to be effectively connected to a wheel, namely a drive wheel, of the vehicle in order to generate drive power at the wheel according to an electrical output from the generator. In particular, the electric motor is designed as a wheel hub motor on a drive wheel of the vehicle. For example, the generator and the electric motor are connected to each other, at least indirectly or directly. In particular, the system can have several electric motors, each driving a wheel or an axle. In particular, there is no mechanical connection between the pedal crank shaft and the wheel designated as the drive wheel.

[0011] According to one embodiment, the system comprises an electrical energy storage device that is electrically connected to the generator and the electric motor. When the vehicle is stationary, the generator can be operated with electrical energy from the energy storage device in such a way that a pedal crank angle of at least 10° and at most 90° is set for the rider to start moving. The energy storage device serves, on the one hand, to store electrical energy, in particular to absorb the electrical energy of the generator, and on the other hand, to provide electrical energy, in particular to feed electrical energy into the electric motor and drive the drive wheel, as well as to feed electrical energy into the generator and position the pedal crank shaft or the pedal cranks arranged thereon.This means that when starting from a standstill, the rider no longer needs to position the pedal cranks but can pedal directly, thus increasing comfort.

[0012] The invention also relates to a vehicle that can be propelled at least partially by muscle power, comprising at least two wheels and a system according to the invention for determining an absolute pedal crank angle. In particular, the vehicle is designed as a bicycle or e-bike. For example, the vehicle can have three or more wheels, wherein either one or more wheels can be electrically driven.

[0013] Furthermore, the invention relates to a method for determining the absolute pedal crank angle of a vehicle that is at least partially propelled by muscle power, wherein, during acceleration, local extreme points are determined from signal data on the change in the angle of the pedal crank shaft using mathematical functions, wherein four local extreme points constitute one total crank revolution, with a first local maximum being determined as a 90° pedal crank angle, and the subsequent extreme points being determined as 180°, 270°, and 360° or 0° pedal crank angles. Thus, a first local minimum is determined as a 180° pedal crank angle, with a second local maximum being determined as a 270° pedal crank angle, and a second local minimum being determined as 360° or 0° pedal crank angles. The reason for this is that the rider starts off with their stronger leg.During acceleration, the cadence increases steadily with each total crank revolution, which also increases the change in angle of the crank arm.

[0014] Furthermore, the invention also relates to a method for determining the absolute pedal crank angle of a vehicle that is at least partially propelled by muscle power. At a constant cadence, local extreme points are determined from signal data on the angular change of the pedal crank shaft using mathematical functions. Four local extreme points constitute one total crank revolution, and a global maximum of the total crank revolution is determined as a 90° pedal crank angle. Subsequent extreme points are determined as 180°, 270°, 360°, and 0° pedal crank angles. This is because the rider applies the greatest torque to the pedals with their stronger leg, and thus the angular change or angular velocity is also at its maximum when the stronger leg can act on the pedal crank shaft at a 90° pedal crank angle. The two methods can be combined.

[0015] The method is preferably extended by using the absolute pedal crank angles to control and regulate the electric motor. This improves the drive of the wheel connected to the electric motor, and in particular increases comfort by ensuring a more constant drive to at least one of the drive wheels. By using absolute rotation angles instead of relative rotation angles or angular velocity, the system reacts not only faster but also more reliably. For example, the power of the electric motor is reduced at pedal crank angles of 90° and 270° using a correction factor. For example, the correction factor is less than 1 and greater than 0. Alternatively or additionally, the power of the electric motor is increased at pedal crank angles of 180° and 360° using a correction factor. For example, the correction factor is greater than 1.This results in at least one drive wheel being driven more constantly.

[0016] Further measures improving the invention are described in more detail below, together with a description of a preferred embodiment of the invention, with reference to the figures. Fig. 1 a highly simplified schematic representation of a bicycle according to the invention with a system for determining an absolute pedal crank angle and Fig. 2 A highly simplified schematic representation of a generator designed as a pedal generator.

[0017] In Fig. Figure 1 is a vehicle 1 according to the invention, which can be propelled at least partially by muscle power, comprising two wheels 10, 20 and a system for determining an absolute pedal crank angle. The vehicle 1 is presented here as a bicycle, in particular as an e-bike.

[0018] A crank shaft 2 is connected to pedals 4 via crank arms 3, with a generator 7, designed as a pedal generator, being effectively connected to the crank shaft 2. An electric motor 8, designed as a wheel hub motor, is effectively connected to the wheel 10 of the bicycle, which is designed as the drive wheel, in order to generate drive power at the wheel 10 according to an electrical output of the generator 7. An electrical energy storage device 9 is arranged on the frame 11 of the bicycle and is electrically connected to the generator 7 and the electric motor 8.

[0019] When the rider pedals, the generator 7 produces electrical power, which serves as a measure of the electrical energy from the energy storage device 9 fed into the electric motor 8. Specifically, the electrical drive power provided by the electric motor 8 at the drive wheel is the product of the electrical power of the generator 7 and a factor selectable by the rider by choosing the driving mode. There is no mechanical connection, in particular no chain or belt drive, between the wheel hub and the pedal crankshaft 2, so the drive wheel can only be driven by the electric motor 8.

[0020] A sensor assembly 5, comprising a rotation angle sensor, for detecting changes in angle or angular velocity of the crank arm 2, is arranged in the area of ​​the crank arm 2. A data processing device 6 is connected to the sensor assembly 5 via signal transmission in order to determine local extreme points from the signal data of the sensor assembly 5 using mathematical functions, with four local extreme points constituting one total crank revolution. During start-up, a first local maximum of the mathematical function is determined as a 90° pedal crank angle, with the subsequent extreme points being determined as 180° pedal crank angle, 270° pedal crank angle, and 360° pedal crank angle.With a substantially constant cadence of the rider, a local maximum, which is also a global maximum of a total crank revolution, is determined as a 90° pedal crank angle, with the subsequent extreme points being determined as 180° pedal crank angle, 270° pedal crank angle and 360° pedal crank angle.

[0021] The absolute pedal crank angles are used to control and regulate the electric motor 8. For example, the drive power of the electric motor 8 is reduced by means of a correction factor at pedal crank angles of 90° and 270°, and increased by means of a correction factor at pedal crank angles of 180° and 360° or 0°. This results in a more constant drive of the drive wheel.

[0022] In Fig.Figure 2 shows the generator 7 arranged on the crank shaft 2 and the crank arms 3, which are non-rotatably connected to the crank shaft 2, with the pedals 4 attached to them, isolated in a coordinate system shown with dashed lines. In this case, only the pedal 4 and the crank shaft 3, on which the rider's stronger leg acts, are labeled with reference symbols. Each pedal 4 receives drive power from the rider.

[0023] For pedal crank angles of 90° and 270°, i.e., when the crank arm 3 is horizontally oriented at either 90° or 270°, local maxima are captured in a mathematical function. For pedal crank angles of 180° and 360° or 0°, i.e., when the crank arm 3 is vertically oriented at either 180° or 360°, local minima are captured in a mathematical function. Reference symbol list 1 vehicle 2. Crankshaft 3 Crankshaft 4 pedals 5 Sensors 6 Data processing device 7 Generator 8 Electric motor 9 Energy storage 10 wheels 11 frames 20-inch wheel

Claims

System for determining an absolute pedal crank angle of a vehicle (1) that is at least partially propelled by muscle power, comprising a pedal crank shaft (2) which is configured to be connected to pedals (4) via pedal cranks (3), a sensor (5) for detecting a change in the angle of the pedal crank shaft (2) and a data processing device (6) which is configured to be connected to the sensor (5) via signal transmission in order to determine local extreme points from signal data of the sensor (5) regarding the change in the angle of the pedal crank shaft (2) using mathematical functions when starting off, wherein four local extreme points constitute one total crank revolution and a first local maximum is determined as a 90° pedal crank angle, wherein the subsequent extreme points are determined as a 180° pedal crank angle, a 270° pedal crank angle and a 360° pedal crank angle. System for determining an absolute pedal crank angle of a vehicle (1) that is at least partially propelled by muscle power, comprising a pedal crank shaft (2) configured to be connected to pedals (4) via pedal cranks (3), a sensor (5) for detecting a change in the angle of the pedal crank shaft (2), and a data processing device (6) configured to be connected to the sensor (5) for signal transmission in order to determine local extreme points from signal data of the sensor (5) regarding the change in the angle of the pedal crank shaft (2) at a substantially constant cadence, using mathematical functions, wherein four local extreme points constitute one total crank revolution, and a global maximum of the total crank revolution is determined as a 90° pedal crank angle, with the subsequent extreme points being determined as 180° pedal crank angle, 270° pedal crank angle, and 360° pedal crank angle. System according to claim 1 or 2, characterized by a generator (7) with a rotor and a stator, wherein the rotor of the generator (7) is connected to the pedal crank shaft (2) in a rotationally fixed manner. System according to claim 3, characterized by an electric motor (8) with a rotor and a stator, wherein the rotor of the electric motor (8) is configured to be connected to a wheel (10) of the vehicle (1) in a driving manner in order to generate a driving power at the wheel (10) according to an electrical power of the generator (7). System according to claim 4, characterized by an electrical energy storage device (9) which is electrically connected to the generator (7) and the electric motor (8), wherein the generator (7) can be operated with electrical energy from the energy storage device (9) when the vehicle (1) is stationary, such that a pedal crank angle of at least 10° to a maximum of 90° is set for starting off. Vehicle (1) that can be propelled at least partially by muscle power, comprising at least two wheels (10, 20) and a system for determining an absolute pedal crank angle according to one of the preceding claims. Method for determining an absolute pedal crank angle of a vehicle (1) that can be propelled at least partially by muscle power, wherein, when starting off, local extreme points are determined from signal data on the angle change of a pedal crank shaft (2) using mathematical functions, wherein four local extreme points form one total crank revolution, wherein a first local maximum is determined as a 90° pedal crank angle, and wherein the subsequent extreme points are determined as a 180° pedal crank angle, a 270° pedal crank angle and a 360° pedal crank angle. Method for determining an absolute pedal crank angle of a vehicle that is at least partially propelled by muscle power (1), wherein, at a constant cadence, local extreme points are determined from signal data on the angle change of a pedal crank shaft (2) using mathematical functions, wherein four local extreme points form one total crank revolution and a global maximum of the total crank revolution is determined as a 90° pedal crank angle, wherein the subsequent extreme points are determined as 180° pedal crank angle, 270° pedal crank angle and 360° pedal crank angle. Method according to claim 7 or 8, wherein the absolute pedal crank angles are used to control and regulate an electric motor (8). Method according to claim 9, wherein the power of the electric motor (8) is reduced by means of a correction factor at a pedal crank angle of 90° and 270° and / or the power of the electric motor (8) is increased by means of a correction factor at a pedal crank angle of 180° and 360°.

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