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DE-102024132762-A1 - System and method for determining an absolute pedal crank angle

DE102024132762A1DE 102024132762 A1DE102024132762 A1DE 102024132762A1DE-102024132762-A1

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.

Inventors

  • Ralf Mannsperger
  • Leon Becker

Assignees

  • Schaeffler Technologies AG & Co. KG

Dates

Publication Date
20260513
Application Date
20241111

Claims (10)

  1. 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) 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) 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 pedal crank angle of 90°, wherein the subsequent extreme points are determined as a pedal crank angle of 180°, a pedal crank angle of 270° and a pedal crank angle of 360°.
  2. 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.
  3. 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.
  4. 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 arranged 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).
  5. 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.
  6. 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.
  7. 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.
  8. 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.
  9. Procedure according to Claim 7 or 8 , wherein the absolute pedal crank angles are used to control and regulate an electric motor (8).
  10. Procedure 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°.

Description

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. For example, the DE 10 2020 215 569 A1 A control method for an electric bicycle with an electric motor as the drive motor. The method comprises the following steps: detection of the rotational speed of the pedal axle, detection of the pedaling force applied by the rider, determination of rider power output as a function of the detected rotational speed and pedaling force, determination of a power deviation between the determined rider power output and a power setpoint, and control of the electric motor to generate motor torque as a function of the determined power deviation, whereby if the detected rider power output is less than the power setpoint, the generated motor power is increased with increasing power deviation. The object of the invention is to provide an alternative system 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 and 7. Preferred embodiments are described in the dependent claims, the description, and the figures. A 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 a change in the angle of the pedal crank shaft, and a data processing device configured to be connected to the sensor for signal transmission in order to determine local extreme points from signal data from the sensor regarding the change in the angle of the pedal crank shaft using mathematical functions during acceleration. Four local extreme points constitute one total crank revolution, and a first local maximum is determined as a 90° pedal crank angle. Subsequent extreme points are determined as 180°, 270°, and 360° pedal crank angles. Extreme points of a mathematical function can be determined by differentiating the function and exist as minima (low points) and maxima (high points). A maximum occurs when the first derivative of the function is zero and the second derivative of the function is less than zero. A minimum occurs when the first derivative of the function is zero and the second derivative of the function is greater than zero. 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. 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 crankshaft or for the angular velocity of the crankshaft 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 angles of 90° and 270°, and the lever arm is minimal at crank angles of 180°, 360°, and 0°, respectively. Furthermore, riders typically have legs of different strength, with the stronger leg capable of applying a greater torque to the crankshaft, resulting in a larger change in angle. This results in a global extreme point, namely a global maximum, in addition to the local extreme points, for each total crank revolution, assuming a substantially constant cadence. 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, with a pedal crank angle of 90° and 270°, the following extreme points are found: Local maxima occur when the crank arms are horizontally oriented. Local minima occur at pedal angles