Method and control device for determining a first time derivative of a pedal force of a muscle-powered vehicle, drive train with control device and muscle-powered vehicle

Abstract

A method is described for determining a first time derivative of a pedal force of a human-powered vehicle (2) for controlling (S3) a drive motor (4) of the vehicle (2). The method comprises reading (S1) information about a pedal force at a pedal (8) of the human-powered vehicle (2) and determining (S2) the first time derivative of the pedal force using a numerical method as a function of the pedal force information. Furthermore, a method is described for controlling (S3) a drive motor (4) of a human-powered vehicle (2), wherein the control (S3) is carried out as a function of a first time derivative of the pedal force determined using the described method. Furthermore, a control device (6) for carrying out such methods is described.In addition, a drive train with such a control device (6) and a muscle-powered vehicle (2) with such a drive train are described.

Description

[0001] The present invention relates to a method for determining a first time derivative of a pedal force of a human-powered vehicle for controlling a drive motor of the vehicle. The present invention further relates to a method for controlling a drive motor of a human-powered vehicle, wherein the control is carried out as a function of a first time derivative of the pedal force determined in this way. Furthermore, the present invention relates to a control device configured to carry out such methods. Furthermore, the present invention relates to a drive train having such a control device and to a human-powered vehicle having such a drive train.

[0002] To control electric motors in human-powered vehicles, such as e-bikes, information on various measured variables of the vehicle is required. For example, DE 10 2021 213 537 A1 describes how a motor of a human-powered vehicle is controlled based on a time derivative of a driver's torque. To achieve more precise control of the motor, the control can be performed based on additional measured variables and their time derivatives. A time derivative of another measured variable must be determined for this purpose.

[0003] Based on this, the object of the invention is to provide a method for determining the first time derivative of a pedal force of a human-powered vehicle. This object is achieved by the subject matter having the features of the independent claims.

[0004] In a first aspect, the present invention relates to a method for determining a first time derivative of a pedal force of a human-powered vehicle for controlling a drive motor of the vehicle. The method can be a computer-implemented method. A computer device, such as a control device of the vehicle, can be configured to carry out steps of the method. The method can be a method for approximately determining the first time derivative of the pedal force. The method can be a numerical method for determining the first time derivative of the pedal force. The first time derivative can be a gradient with respect to time.

[0005] The vehicle can be a bicycle, an e-bike, a pedelec, or a cargo bike. The pedal force can be a force on at least one pedal of the vehicle, for example, on two pedals. The pedal force can be a force applied by a driver of the vehicle to one or more pedals of the vehicle. For example, the vehicle can have a crank with a pedal crankshaft, and the crank can be rotatably mounted in a frame of the vehicle. Crank arms of the crank can be rotationally fixedly connected to the pedal crankshaft, and a pedal can be rotatably mounted at one end of each crank arm. The pedal crankshaft can be a pedal crankshaft. The driver can apply muscle power as driving force via the pedals and thus to the crank to drive the vehicle.

[0006] The drive motor of the vehicle can be an electric motor. The first time derivative of the pedal force can be used to control and alternatively or additionally to regulate the drive motor. For example, the first time derivative of the pedal force can be used as a parameter of a speed control and alternatively or additionally of a speed control of the drive motor, for example to improve the accuracy of the speed control and alternatively or additionally of the speed control. Alternatively or additionally, the first time derivative of the pedal force can be used as a parameter of a torque control and alternatively or additionally of a torque control of the drive motor, for example to improve the accuracy of the torque control and alternatively or additionally of the torque control.

[0007] The method comprises reading in information about a pedal force on a pedal of the human-powered vehicle. Pedal force can be read in on one or more, for example all, pedals of the vehicle. Reading in information can be a reading in of at least one piece of information, for example exactly one piece of information or several pieces of information. The pedal force information can include measured values ​​for the pedal force as a function of time. For example, information about the pedal force can include a temporal progression of the pedal force. The pedal force can be a measured variable that can be measured using a sensor, for example. For example, measured values ​​for the pedal force can be time-discrete. The pedal force can be a discrete function of time. The pedal force can change while the driver of the vehicle is pedaling.Information about this changing pedal force as a function of time can be read in when reading pedal force information.

[0008] The method further comprises determining the first time derivative of the pedal force using a numerical method as a function of the pedal force information. Determining the first time derivative of the pedal force using the numerical method can be an approximate determination or estimation of the first time derivative of the pedal force using the numerical method. Determining the first time derivative of the pedal force can be performed as a function of time as a function of the measured values ​​of the pedal force.

[0009] Thus, a method is provided which can determine the first time derivative of the pedal force at the vehicle pedal in order to control the vehicle's drive motor depending thereon. Such a method can be carried out independently of a dedicated sensor for the first time derivative of the pedal force. Such a method can also be used for a human-powered vehicle which has fewer sensors, for example, no such dedicated sensor for directly determining the first time derivative of the pedal force. This makes it possible to reduce the number of electrical interfaces in the vehicle. This allows for simplified system integration of a control device executing the method in the vehicle with additional sensors. This makes it possible to reduce the number of error sources for such a method and for a control device executing the method.Thus, the method allows numerical methods to be used to determine the first time derivative of the pedal force and thus to control the drive motor. The state variable of the first time derivative of the pedal force can thus be determined independently of an additional sensor, for example. Providing additional sensors on the vehicle may be uneconomical.

[0010] In addition, the state variable of the first time derivative of the pedal force can be determined using such a method. This additional measured variable, the first time derivative of the pedal force, can be used to control the vehicle's drive motor. This allows for more precise control.

[0011] Such a method can represent a good compromise between noise reduction and accuracy for determining the first time derivative of pedal force without an additional sensor.

[0012] According to a further embodiment, the method can be characterized in that the pedal force information can be acquired using a sensor for reading the pedal force information. The acquisition of information can be the acquisition of at least one piece of information, for example, of exactly one piece of information or of multiple pieces of information. For example, the pedal force information can comprise measured values ​​of the pedal force that are equidistant in time. For example, a temporal progression of the pedal force can be acquired.

[0013] The sensor can be a sensor specifically designed for recording measured values ​​of pedal force as a function of time. The sensor can have one or more piezo elements. Alternatively or additionally, the sensor can have one or more strain gauges. For example, the sensor can be arranged on or in the pedal. For example, the sensor can be arranged in a surface of the pedal. For example, each pedal can have a sensor for recording pedal force information. Recording pedal force information can be carried out using more than one sensor, for example, one sensor for each of two pedals of a vehicle. When recording pedal force information, the total force applied by the driver to the pedals can be recorded.

[0014] The recording can be performed at a constant sampling rate. The recording can be performed cyclically, for example, periodically. In the step of reading the pedal force information, the pedal force information recorded by the sensor can be read.

[0015] Thus, the method can be carried out by a control device with a sensor for detecting pedal force information. Such a sensor for detecting pedal force information is already present in many human-powered vehicles, for example, for driver performance diagnostics. Additional sensors and the information and measured values ​​detected by these sensors are therefore not necessary to carry out the method, for example, to approximately determine the first time derivative of the pedal force in order to control a drive motor. This makes it possible to provide a particularly cost-effective method, since such a method is, for example, dependent solely on a sensor for detecting pedal force.

[0016] According to a further embodiment, the method can be characterized in that the numerical method is a differentiating low-pass filter. A differentiating low-pass filter can be used for the differentiating low-pass filter. According to a systems-theoretical interpretation, determining the first time derivative of the pedal force using such a differentiating low-pass filter can be the numerical method for determining the first time derivative of the pedal force as a function of pedal force information.

[0017] Such a method can be a more accurate numerical method for determining the first time derivative of the pedal force from the pedal force than using a difference quotient. A simple difference quotient of the pedal force as a function of time for determining the first time derivative of the pedal force can be less accurate than such a differentiating low-pass filtering. Subsequent low-pass filtering of a value of the first time derivative of the pedal force from the time-dependent pedal force determined using a difference quotient can also be less accurate than determining the first time derivative of the pedal force using differentiating low-pass filtering.

[0018] In alternative methods, low-pass filtering is performed first, and then the difference quotient is calculated based on the filtering. Applying the difference quotient in this way, possibly with downstream or upstream low-pass filters, often amplifies the measurement noise, and aliasing effects can occur as a result of the difference quotient. These aliasing effects cannot be compensated for even by the downstream low-pass filter.

[0019] According to a further embodiment, the method can be characterized in that the differentiating low-pass filtering is linear and time-invariant. The differentiating low-pass filter can be a linear and time-invariant filter. The low-pass filter can exhibit a linear transfer behavior while behaving in a time-invariant manner, i.e., filter independently of time.

[0020] This allows for effective suppression of measurement noise when determining the first time derivative of the pedal force. The measurement noise can be captured when capturing the pedal force information. This can result in high accuracy when determining the first time derivative of the pedal force. At the same time, the pedal force can be differentiated as a function of time, and this differentiated signal can be smoothed, filtering out measurement noise.

[0021] According to a further embodiment, the method can be characterized in that a filter for the linear and time-invariant low-pass filtering is an FIR filter. The FIR filter has, for example, an impulse response with a finite length.

[0022] A method that uses such a FIR filter as a differentiating low-pass filter can be guaranteed to be numerically stable when determining the first time derivative of the pedal force. The differentiating low-pass filter can be implemented as a convolution sum, for example, as a weighted sum of a finite number of measured values ​​of the pedal force. This avoids the need for recursion, which could lead to unstable behavior of the method, to determine the first time derivative of the pedal force. The method can therefore be computationally efficient.

[0023] Furthermore, the method can react quickly to changing pedal force values. This can be relevant if the determined value of the first time derivative of the pedal force is used, for example, for a safety function and requires a short response time. The convolution sums can be efficiently calculated in a control device executing the method, such as in an embedded system in a vehicle. For example, this can be done using a multiply-accumulate (MAC) unit. This can reduce development effort, for example, if the method is implemented in such an embedded system using fixed-point arithmetic.

[0024] In contrast to IIR filters, i.e. filters with an infinite impulse response, a guaranteed statement can be made as to the transition period after which the change in the first time derivative of the pedal force during actual pedaling by the driver is reflected in the determined first time derivative of the pedal force, determined from the pedal force. Such a finite transition period can be determined. A method using an IIR filter can, for example, be numerically unstable and lead to overshoot when determining the first time derivative of the pedal force from the pedal force. This can also minimize the development effort for a method such as the one described here, since the time until the determined first time derivative of the pedal force reaches its final value can be defined using a maximum setting period.

[0025] According to a further embodiment, the method can be characterized in that the FIR filter is an algebraic numerical differentiator. An example and further explanation of an algebraic numerical differentiator, also referred to as a derivative estimator, can be found in the following documents: Algebraic numerical differentiator in theory and application, Lothar Kiltz, 2017 Saarbrücken; Survey on algebraic numerical differentiation: historical developments, parameterization, examples, and applications, Othmane, Kiltz, Rudolph, 2022, International Journal of Systems Science. The algebraic numerical differentiator can be used for algebraic numerical differentiation. According to an approximation-theoretic interpretation of algebraic numerical differentiation, the desired first time derivative of the pedal force can be locally approximated by a polynomial.The polynomial can be evaluated at the point in time at which it locally approximates the desired first time derivative of the pedal force. For a specific time range, the steps of local approximation using a polynomial and evaluation of the polynomial at a specific point in time can be repeated for different points in time. This allows numerical differentiation of the measured pedal force values ​​to be performed.

[0026] Determining the first time derivative of pedal force from the pedal force as a function of time can be done numerically rather than analytically for discrete values ​​of pedal force as a function of time. Such an algebraic numerical differentiator can represent a good compromise for deriving the pedal force with good noise rejection and accuracy for determining the first time derivative of pedal force.

[0027] According to another embodiment, the method may be characterized in that the FIR filter is a Savitzky-Golay filter. According to one embodiment, the algebraic numerical differentiator may be a Savitzky-Golay filter. According to one embodiment, the linear and time-invariant differentiating low-pass filter may be a Savitzky-Golay filter. With such a Savitzky-Golay filter, the method may be a smoothing method based on a polynomial least-squares approximation.

[0028] A second aspect of the present invention relates to a method for controlling a drive motor of a human-powered vehicle. The control can be carried out as a function of a first time derivative of the pedal force, which is determined using a method according to an embodiment of the first aspect of the present invention. Thus, the method for determining the first time derivative of the pedal force can be carried out first, and then the method for controlling the drive motor can be carried out using the first time derivative of the pedal force thus determined. A control parameter can be determined as a function of the determined first time derivative of the pedal force and sent to the drive motor for controlling the drive motor.

[0029] The drive motor can be configured to provide drive power to assist the driver of the vehicle in propelling the vehicle. The drive motor can be an electric motor. The drive motor can be used to relieve the driver's workload while driving and, alternatively or additionally, to increase the vehicle's range. The drive motor can be configured to provide drive power to relieve the driver's workload. For example, drive power provided by the driver as muscle power and applied to the pedals and crank, and drive power provided by the drive motor can be used to propel the vehicle. The drive power provided by the drive motor can relieve the driver's workload.

[0030] This allows the drive motor to be controlled as a function of the first time derivative of the pedal force. This allows the drive motor to be controlled as a function of another state variable of the vehicle, allowing the drive motor to be controlled more precisely. The control can be a control and, alternatively or additionally, a regulation of the drive motor. Further features, embodiments, and advantages can be found in the descriptions of the first aspect. Conversely, features, embodiments, and advantages of the second aspect also represent features, embodiments, and advantages of the first aspect.

[0031] According to a further embodiment, the method can be characterized in that, for controlling the drive motor, a determination is made as a function of the determined first time derivative of the pedal force as to whether a crank of the vehicle is being moved. Moving the crank can be a rotation of the crank in the vehicle's bearing. The first time derivative of the pedal force determined via the approximate derivative of the pedal force signal as a function of time can thus be used to determine whether the driver is pedaling or not. For example, the determined first time derivative of the pedal force can be compared to a threshold value, and based on the comparison, it can be determined whether the crank is moving or not. When the driver pedals, the pedal force changes over the course of one crank revolution.For example, if the first time derivative of the pedal force is below a certain threshold, it is determined that the crank is no longer being moved and the rider is not pedaling. If the first time derivative is above the certain threshold, it can be determined that the crank is being moved due to the rider's pedaling. For example, the drive motor can provide assistance if it has been determined that the crank is being moved.

[0032] According to a further embodiment, the method can be characterized in that the drive motor can be configured to provide drive power to assist the driver of the vehicle in driving the vehicle. The control can comprise switching on and, alternatively or additionally, switching off the assistance provided by the drive motor. For example, if the determined first time derivative is above a first threshold value, the assistance can be switched on. If the determined first time derivative is below a second threshold value, the assistance can be switched off. The first and second threshold values ​​can be the same or different. Thus, the driver assistance provided by the drive motor in driving the vehicle can be switched on and off.This can be done depending on the determined first time derivative of the pedal force, for example, only depending on the determined first time derivative of the pedal force. Alternatively, the assistance can also be switched on and off depending on other state variables or measured variables of the vehicle. One such additional measured variable or state variable could be, for example, the cadence of the crank.

[0033] A third aspect of the present invention relates to a control device. The control device can further comprise a sensor for detecting information about the pedal force. This sensor can therefore be a force sensor, for example. For example, the sensor can be configured to detect the pedal force on the pedal as a function of time. The force sensor can comprise one or more piezo elements. Alternatively or additionally, the force sensor can comprise one or more strain gauges.

[0034] The control device can be configured to execute a method according to an embodiment of the first two aspects of the present invention. Such a control device with such a force sensor can be designed particularly inexpensively and with efficient installation space. An additional sensor may not be necessary to determine the first time derivative of the pedal force. This is because the method executable by the control device allows the first time derivative of the pedal force to be determined depending on the pedal force detected by the force sensor.

[0035] The control device can further be configured to control a drive motor of a vehicle. For this purpose, the control device can be configured to determine a control parameter depending on the determined first time derivative of the pedal force. The control device can be communicatively connected to the drive motor. Furthermore, the control device can be configured to send the determined control parameter to the drive motor for controlling the drive motor. Controlling the drive motor can comprise controlling and, alternatively or additionally, regulating a rotational speed and, alternatively or additionally, a torque of the drive motor. The determined first time derivative of the pedal force can be used as a parameter during control and, alternatively or additionally, during regulation, for example, to improve accuracy during control and, alternatively or additionally, during regulation.Further features, embodiments, and advantages can be found in the descriptions of the first and second aspects. Conversely, features, embodiments, and advantages of the third aspect also represent features, embodiments, and advantages of the first and second aspects.

[0036] A fourth aspect of the present invention relates to a drive train with a control device according to an embodiment of the third aspect of the present invention. Furthermore, the drive train comprises a drive motor and a pedal. The drive train comprises, for example, a crank, two crank arms arranged thereon in a rotationally fixed manner, and a rotatably mounted pedal at one end of each crank arm. The drive train may be free of further sensors. Further features, embodiments, and advantages can be found in the descriptions of the first to third aspects. Conversely, features, embodiments, and advantages of the fourth aspect also represent features, embodiments, and advantages of the first to third aspects.

[0037] A fifth aspect of the present invention relates to a human-powered vehicle with a drive train according to an embodiment of the fourth aspect of the present invention. The human-powered vehicle can be a bicycle, an e-bike, a pedelec, or a cargo bike. Further features, embodiments, and advantages can be found in the descriptions of the first to fourth aspects. Conversely, features, embodiments, and advantages of the fifth aspect also represent features, embodiments, and advantages of the first to fourth aspects.

[0038] According to one embodiment, the muscle-powered vehicle can be characterized in that the control device can be integrated into a housing with the drive motor. The housing can be mechanically connected to a frame of the vehicle, for example, to a down tube of the two-wheeled vehicle. Fig. 1 schematically shows steps of a method for determining a first time derivative of a pedal force of a muscle-powered vehicle and a method for controlling a drive motor of the vehicle. Fig. 2 schematically shows a vehicle with a drive train and a control device for carrying out steps of the schematically shown in Fig. 1 shown procedure.

[0039] Fig. 1 schematically shows steps of a method for determining a first time derivative of the pedal force of a muscle-powered vehicle 2. Furthermore, Fig. 1 schematically shows steps of a method for controlling S3 a drive motor 4 of the vehicle 2.

[0040] Fig. Figure 2 shows schematically the muscle-powered vehicle 2. In one embodiment of the invention, the muscle-powered vehicle 2 is a pedelec with a drive motor 4 designed as an electric motor. The vehicle 2 has a drive train with a control device 6 as well as the drive motor 4 and a pedal 8. Fig.2, the pedal 8 is shown only schematically and represents all of the pedals 8 of the vehicle 2. The vehicle 2 has a crank (not shown), and two crank arms are arranged on the crank in a rotationally fixed manner. A pedal 8 is rotatably mounted at one end of each crank arm. Via the pedals 8, a driver of the vehicle 2 can apply muscle power to the pedals 8, and this muscle power can be used to drive the vehicle 2. The drive motor 4 is configured to also apply drive power to drive the vehicle. The control device 6 is communicatively connected to the drive motor 4. The control device 6 and the drive motor 4 are integrated in a housing 12. The housing 12 is mechanically connected to a frame of the vehicle 2.

[0041] Furthermore, the vehicle 2 has a sensor 10. The sensor 10 is configured to detect information about a pedal force on the pedal 8. Each pedal 8 is assigned a sensor 10. In the embodiment shown, the sensor 10 is formed separately from the pedal 8. In an alternative embodiment, the sensor 10 is integrated into the pedal 8 and is part of the pedal 8.

[0042] Sensor 10 is a force sensor and has a piezo element for detecting S0 the pedal force information. The pedal force is detected as a measured variable as pedal force information. Measurement values ​​of the pedal force are recorded as a function of time. The detection SO is performed at a constant sampling rate, i.e., at a temporally constant sampling rate for a constant, cyclical detection SO of the pedal force at pedal 8. In the detection S0 step, equidistantly spaced measurement values ​​of the pedal force at pedal 8 are detected. Pedal force is detected at all pedals 8.

[0043] The method comprises reading S1 of information about the pedal force at pedal 8 of the human-powered vehicle 2. In this process, the pedal force information acquired in the acquisition step S0 is previously read in. Thus, measured and acquired time-dependent measured values ​​of the pedal force are read in. The pedal forces acquired at all pedals 8 are read in.

[0044] The method further includes determining S2 the first time derivative of the pedal force. Determining S2 is performed using a numerical method based on the pedal force information. The numerical method is a differentiating low-pass filter for approximately determining the first time derivative of the pedal force from the pedal force as a function of time, and thus from discrete measured values ​​of the pedal force as a function of time.

[0045] The determination S2 of the first time derivative of the pedal force is performed using a differentiating low-pass filter. The differentiating low-pass filter is a linear and time-invariant filter, and thus the differentiating low-pass filtering is linear and time-invariant. This filter, here the differentiating low-pass filter, for the linear and time-invariant low-pass filtering is a FIR filter. This FIR filter is implemented as a convolution sum and, in the embodiment shown, can be represented as a weighted sum of a finite number of pedal force values ​​as a function of time. This guarantees numerically stable FIR filters. The FIR filter is an algebraic numerical differentiator. In the embodiment shown, the FIR filter is a Savitzky-Golay filter.

[0046] After the first time derivative of the pedal force has been approximately determined from the pedal force information, the control S3 of the drive motor 4 of the vehicle 2 is carried out. This control S3 is carried out as a function of the determined first time derivative of the pedal force.

[0047] For controlling S3 of the drive motor 4, a determination S3.0 is made as to whether the crank of the vehicle 2 is being moved, depending on the determined first time derivative of the pedal force. Moving the crank in this case means turning or rotating the crank. If, for example, it is determined that the crank is not moving, the control S3 of the drive motor is carried out differently than if it is determined that the crank is moving. Thus, the drive motor 4 is controlled with a target torque that is equal to zero if it is determined that the crank is not moving. If it is determined that the crank is moving, the drive motor 4 is controlled with a target torque that is not equal to zero. When determining S3.0 whether the crank is being moved, the determined first time derivative of the pedal force is compared with a specific threshold value.If the determined first time derivative of the pedal force is below the determined threshold, it is determined that the crank is not being moved. If the determined first time derivative of the pedal force is above the determined threshold, it is determined that the crank is being moved.

[0048] The drive motor 4 is configured to provide drive power to assist the driver of the vehicle 2 in driving the vehicle 2. The control S3 comprises a switching on S3.1 of the assistance by the drive motor 4. If it is determined that the determined first time derivative of the pedal force is above a first threshold value, the switching on S3.1 of the assistance is carried out. Drive power is then provided by the drive motor 4 to drive the vehicle 2. The driver is relieved of the load when driving the vehicle 2, specifically when the driver pedals and thus the determined first time derivative of the pedal force is above the first threshold value.

[0049] Control S3 includes switching off S3.2 the assistance by the drive motor. If it is determined that the determined first time derivative of the pedal force is below a second threshold, the assistance is switched off S3.2. Then, no drive force is provided by the drive motor 4 to drive the vehicle 2. The driver is not relieved of stress when driving the vehicle 2, for example because the driver is not pedaling and thus the determined first time derivative of the pedal force is below the second threshold. The first and second thresholds are identical. Thus, switching on S3.1 and switching off S3.2 are carried out around a common threshold. In an alternative embodiment, the second threshold is smaller or larger than the first threshold.

[0050] The control device 6 with the sensor 10 is thus designed to save space and installation space by omitting a dedicated sensor for determining the first time derivative of the pedal force. Furthermore, such a control device 6 with such a sensor 10 is easier to maintain and cheaper to purchase and maintain than a vehicle 2 with a dedicated sensor for determining the first time derivative of the pedal force. Furthermore, such a method can be used to determine the state variable of the first time derivative of the pedal force for controlling the drive motor. Reference symbol 2 vehicles 4 drive motor 6 Control device 8 Pedal 10 Sensor 12 housings S0 Acquisition of information of a pedal force S1 Reading pedal force information S2 Determining a first time derivative of the pedal force using a numerical method S3 Control of the drive motor S3.0 Determine whether a crank of the vehicle is moved S3.1 Activation of support by the drive motor S3.2 Switching off the support by the drive motor QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2021 213 537 A1

[0002]

Claims

[1] Method for determining a first time derivative of a pedal force of a muscle-powered vehicle (2) for controlling (S3) a drive motor (4) of the vehicle (2), comprising the steps of: reading (S1) information of a pedal force at a pedal (8) of the muscle-powered vehicle (2); and determining (S2) the first time derivative of the pedal force using a numerical method as a function of the pedal force information. [2] Method according to claim 1, characterized by that a detection (S0) of the information of the pedal force is carried out with a sensor (10) for the reading (S1) and that the detection (S0) is carried out with a constant sampling rate. [3] Method according to one of the preceding claims, characterized by that the numerical method is a differentiating low-pass filtering. [4] Method according to claim 3, characterized bythat the differentiating low-pass filtering is linear and time-invariant. [5] Method according to claim 4, characterized by that a filter for linear and time-invariant low-pass filtering is an FIR filter. [6] Method according to claim 5, characterized by that the FIR filter is an algebraic numerical differentiator. [7] Method according to one of claims 5 or 6, characterized by that the FIR filter is a Savitzky-Golay filter. [8] Method for controlling (S3) a drive motor (4) of a muscle-powered vehicle (2), wherein the control (S3) is carried out as a function of a first time derivative of a pedal force, which is determined by a method according to one of the preceding claims. [9] Method according to claim 8, characterized bythat for the control (S3) of the drive motor (4) a determination (S3.0) is carried out as a function of the determined first time derivative of the pedal force as to whether a crank of the vehicle (2) is moved. [10] Method according to one of claims 8 or 9, characterized by that the drive motor (4) is designed to provide drive power to assist a driver of the vehicle (2) in driving the vehicle (2) and that the control (S3) comprises switching on (S3.1) and switching off (S3.2) the assistance by the drive motor (4). [11] Control device (6) which is arranged to carry out a method of the preceding claims. [12] Drive train with a control device (6) according to claim 11 and with a drive motor (4) and with a pedal (8). [13] Muscle-powered vehicle (2) with a drive train according to claim 12. [14] Muscle-powered vehicle (2) according to claim 13, characterized by that the control device (6) is integrated in a housing (12) with the drive motor (4) and the housing (12) is mechanically connected to a frame of the vehicle (2).

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