Method for controlling a drive train, drive train and vehicle

Abstract

A method for controlling a drive train (4) of a vehicle (2) is described, wherein the drive train (4) has at least one shaft (6) which is accelerated when the vehicle (2) is driven by a driver, wherein the drive train (4) has a drive motor (12) for providing drive force to assist the driver of the vehicle (2) in driving the vehicle (2). The method comprises determining (S1) an angular jerk of the shaft (6) and controlling (S2) the drive motor (12), wherein the assistance by the drive motor (12) is switched on or off depending on the determined angular jerk. Furthermore, a drive train (4) for a vehicle (2) and a vehicle (2) having such a drive train (4) are described.

Description

[0001] The present invention relates to a method for controlling a vehicle's drivetrain. Furthermore, the present invention relates to a vehicle's drivetrain and to a vehicle with such a drivetrain, wherein the vehicle can be powered at least temporarily by muscle power.

[0002] Vehicles that can be propelled at least temporarily by muscle power, such as bicycles, e-bikes, pedelecs, or cargo bikes, may also have a drive motor to assist propulsion. For example, a pedelec, as a muscle-powered vehicle, may have an electric motor to provide assistance. The assistance provided by the drive motor must be controlled. For safety reasons, the assistance may only be provided when the rider is pedaling. To determine whether the rider is pedaling, rider torque can be measured. Rider torque is the torque applied by the rider to the vehicle's crankshaft to propel the vehicle using muscle power. Methods and systems are known in the art that control the drive motor based on the rider torque.

[0003] For example, DE 10 2022 132 256 A1 describes how a driver torque is detected by a sensor and the drive motor is controlled accordingly. Methods and systems are also known in the prior art that control the drive motor based on the first time derivative of the driver torque. Such a sensor for detecting the driver torque increases the system complexity of the vehicle. Furthermore, such a sensor can fail or detect an incorrect value for the driver torque.

[0004] DE 10 2010 048 592 A1 relates to a bottom bracket system for pedelecs with a mid-drive motor concept, which enables control of the motor power, especially at high motor powers and long gear ratios, through the measurement of torque and crank speed on both sides and the integration of a freewheel between the crankshaft and the drive sprocket.

[0005] The object of the invention, starting from the prior art, is to improve the control of the drive motor of a vehicle that is at least temporarily powered by muscle power. This object is achieved by the subject matter with the features of the independent claims. Advantageous further developments are described in the dependent claims.

[0006] The invention relates, in a first aspect, to a method for controlling the drivetrain of a vehicle. The vehicle can be, for example, a bicycle, e-bike, pedelec, or cargo bike that can be powered, at least temporarily, by muscle power. The method for controlling the drivetrain can be a method for controlling a drive motor, such as an electric motor of the drivetrain. Steps of the method can, for example, be carried out using a control device of the vehicle.

[0007] The drivetrain includes a shaft that is accelerated when the vehicle is propelled by a rider. This shaft can be the vehicle's crankshaft. Crank arms can be rigidly connected to the crankshaft. For example, two crank arms can be rigidly connected to the crankshaft, with a pedal rotatably mounted at one end of each crank arm. The crankshaft can therefore also be called a pedal crank. The crankshaft is rotatably mounted to the vehicle's frame by means of a bearing. This bearing can be a rolling bearing, such as a ball bearing, a needle bearing, or a roller bearing. The rider's power is transmitted via the crankshaft to propel the vehicle.

[0008] The shaft can be directly connected to the crankshaft. The shaft can be at least indirectly connected to the crankshaft, for example via a gearbox. The shaft can be mechanically operatively connected to the crankshaft. When the rider propels the vehicle using muscle power, the shaft can be accelerated along with the crankshaft. An acceleration of the shaft, such as angular or rotational acceleration, can be directly correlated with an acceleration of the crankshaft; for example, the accelerations can be linearly related. For example, the acceleration of the shaft can be identical to the acceleration of the crankshaft. An angular jerk of the shaft can be directly correlated with an angular jerk of the crankshaft; for example, the angular jerks can be linearly related. For example, the angular jerk of the shaft can be identical to the angular jerk of the crankshaft.The angular jerk can be the first time derivative of the angular acceleration.

[0009] The drivetrain includes a drive motor to provide power to assist the driver in propelling the vehicle. The drive motor can be an electric motor. It can be used to relieve the driver of effort while driving and, alternatively or additionally, to increase the vehicle's range. The drive motor can be configured to provide power to assist the driver. For example, it can utilize power provided by the driver's muscle power to the pedals and crank arm, as well as power provided by the drive motor to propel the vehicle. The power provided by the drive motor can thus relieve the driver of effort.

[0010] The method involves determining the angular jerk of the shaft. A time-dependent angular jerk can be determined, for example, for time-equidistant values. For instance, a time-discrete function can be defined as the angular jerk. The angular jerk of the pedal crank shaft can be determined. The determination of the angular jerk can be performed directly or indirectly. The angular jerk can be determined directly using a sensor. Alternatively or additionally, the angular jerk can be determined indirectly, depending on another measured variable.

[0011] The method further includes controlling the drive motor, whereby the motor's assistance is activated and deactivated depending on a specific angular jerk. For example, an initial angular jerk value can be determined at a specific time, and the drive motor can be controlled such that assistance is activated based on this initial angular jerk. This initial angular jerk can correspond to a value indicating that the rider has begun pedaling.

[0012] Based on the angle of jerk, a state transition from a state in which the rider is not pedaling to a state in which the rider is pedaling can be detected. When the assistance is engaged, for example, drive power is provided by the drive motor to propel the vehicle and transferred, for example, to a driven wheel of the vehicle.

[0013] For example, a second angular jerk can be detected at a later time than the first. This second angular jerk can differ from the first in sign and, alternatively or additionally, in magnitude. The second angular jerk can correspond to a value indicating that the rider is no longer pedaling and, for example, is merely resting their feet on the pedals. Based on the angular jerk, a transition from a state in which the rider is pedaling to a state in which the rider is not pedaling can be detected. For example, the sign of the second angular jerk can be different from the sign of the first angular jerk. The drive motor can then be controlled such that, depending on this second angular jerk, the assistance from the drive motor is switched off.When the assistance is switched off, for example, no driving power is provided by the drive motor to propel the vehicle.

[0014] This method makes it particularly easy to detect when the rider is pedaling and, depending on this, to switch the assistance from the drive motor on or off. Pedaling can be determined by measuring the angular jerk of the shaft, where the shaft is at least indirectly connected to the crank axle, which is directly accelerated by the rider while pedaling. As described in the previous example, the first value of the angular jerk is measured, thus indicating, for example, that the rider has started pedaling. If the second value of the angular jerk is measured, for example, a value opposite in sign to the first value, it is determined that the rider has stopped pedaling. Then the drive motor and, alternatively or additionally, its assistance are switched off.

[0015] According to the law of conservation of angular momentum, there is a relationship between the sum of all torques acting on a shaft, the shaft's moment of inertia, and the shaft's angular acceleration. Thus, the sum of the applied torques equals the shaft's moment of inertia multiplied by the shaft's angular acceleration. Similarly, the sum of the first time derivatives of the applied torques equals the moment of inertia multiplied by the shaft's angular jerk. The shaft's angular jerk, and therefore that of the pedal crank (which is indirectly accelerated by the shaft), is positively correlated with the first time derivative of a rider torque applied to the shaft, for example, the pedal crank. The rider torque can be the torque applied by the rider to propel the vehicle. The shaft's moment of inertia can be predetermined and stored as a hard-coded value on the control unit.By determining the angular jerk, the first time derivative of the driver's torque can be deduced. Control can therefore be carried out in at least indirect relation to the first time derivative of the driver's torque, without having to directly measure the driver's torque or directly determine its first time derivative.

[0016] Deactivating the drive motor's assistance when the rider is not pedaling may be necessary to increase safety. Compared to conventional methods, which use a torque sensor to measure and determine the rider's torque applied to the crank axle, or even calculate a first time derivative of the rider's torque, this method allows for particularly simple detection of the rider's pedaling. This is achieved by determining the angular jerk. Determining rider torque with a dedicated torque sensor is typically comparatively complex due to rotating parts on the crank axle. Furthermore, the necessary installation space for such a torque sensor is required, which can increase development and production costs as well as system complexity.Adding such a sensor to the vehicle also necessitates an increase in the number of electrical and electronic interfaces required to connect the sensor to the vehicle's existing power supply and to communicate with other electronic units. Furthermore, like any component, such a sensor can malfunction or fail, potentially reducing the vehicle's reliability, availability, and safety. The method described here reduces the number of sensors and electrical and electronic interfaces required. Often, a sensor for measuring another parameter is already present, and the angular jerk can be determined based on this measurement.

[0017] Some vehicles powered at least partially by muscle power have a freewheel between the crank axle and the driven wheel. The freewheel can be open or closed. When the freewheel is closed, power applied to the crank axle can be transferred to the driven wheel to propel the vehicle. When the freewheel is open, no power is transferred from the crank axle to the driven wheel to propel the vehicle. Similarly, when no power is transferred, no rider torque is applied to the crank axle, as there is no resistance while pedaling. For example, if the vehicle is already moving before the rider begins pedaling, the freewheel is open.When the rider begins pedaling, the freewheel is still open, and the crank arm exhibits a non-zero angular jerk. After a specific rotation of the crank arm through a certain angle, the freewheel engages. Drive force is then transmitted, and a non-zero rider torque is applied to the crank arm. Therefore, the angular jerk of the arm is non-zero at a given moment, while no rider torque is yet being applied. This method allows for earlier detection of whether the rider is pedaling compared to conventional methods and based on the time derivative of the rider torque.According to this, the method offers a way to switch the support from the drive motor on or off depending on the rider's pedaling, and at the same time the detection time of pedaling can be reduced, which can improve comfort and safety, for example.

[0018] Detection accuracy can also be improved by eliminating the need to wait for rider torque to be applied. Safety can be enhanced by allowing the rider to anticipate the activation or deactivation of the drive motor's assistance based on pedaling. Furthermore, determining the angular jerk is generally less complex than determining the torque at the crank axle or calculating the first time derivative of the torque, for example, because fewer additional sensors on the vehicle are required.

[0019] According to a further embodiment, the method can be characterized in that, during steering, assistance from the drive motor can be engaged when the specific angular jerk exceeds a first threshold. Engaging the assistance can involve the drive motor providing drive power. The first threshold can, for example, be defined such that the angular jerk is greater than the first threshold when the rider begins pedaling. For instance, the rider can begin pedaling, and thus the angular jerk can exceed the first threshold.

[0020] Thus, depending on the first threshold value, which can be stored as a hard-coded value on the vehicle's control unit, an objective limit for activating the drive motor's assistance can be defined. This allows the point at which pedaling begins to be detected. Therefore, this method enables event detection of the start of pedaling by determining the angular jerk.

[0021] According to a further embodiment, the method can be characterized in that, during control, the assistance provided by the drive motor can be switched off if the specified angular jerk falls below a second threshold. Switching off the assistance can mean ceasing the provision of the drive force by the drive motor. The second threshold can be the same as or different from the first threshold. The first and second thresholds can be different. For example, the first and second thresholds can have opposite signs. The magnitude of the first threshold can be the same as or different from the magnitude of the second threshold.

[0022] This allows the point at which pedaling ceases to be detected. Therefore, this method can be used to implement event detection regarding the cessation of pedaling by determining the angular jerk.

[0023] For example, the angular jerk can be positive at an initial point in time and exceed the first threshold value, which can be positive. This indicates that the rider is pedaling at that first point in time and applying muscle power to propel the vehicle. This event is stored in the control unit. For example, the rider might start pedaling, and thus the angular jerk of the shaft might be positive at that first point in time. At a later, second point in time, the angular jerk can be negative if, for example, the rider stops accelerating the crank shaft and begins pedaling at a constant frequency. If the rider then pedals at a constant frequency, the angular jerk will initially be zero. At a later, third point in time, the angular jerk can again be negative if, for example, the rider stops pedaling.The cadence can decrease, the angular acceleration of the wave can therefore become negative, and consequently, the angular jerk can be negative. The occurrence of a second negative angular jerk after a positive one can therefore indicate that the rider has stopped pedaling. For example, the angular jerk can fall below the second threshold, which can be negative. This can then be used to determine, for instance, that the rider is no longer pedaling.

[0024] For example, a hysteresis effect can be provided by the method if the magnitudes of the first and second thresholds are different. The magnitude of the first threshold can be greater than the magnitude of the second. If the magnitude of the first threshold is greater than the magnitude of the second, for instance, the assistance can only be engaged at a larger angular jerk, whereas the assistance can be disengaged at a smaller angular jerk. This ensures, for example, that the assistance only engages when the rider changes the angular acceleration of the shaft sufficiently quickly by applying muscle force to the pedals and crank axle, thus causing the angular jerk to exceed this first threshold.Simultaneously, the smaller value of the second threshold ensures that the rider has to change their angular acceleration less quickly than they did when starting to pedal. The assistance can then be switched off. This allows the deactivation of the drive motor's assistance to be controlled via the second threshold.

[0025] According to a further embodiment, the method can be characterized in that an additional measured variable can be determined on the drive train. This additional measured variable could be, for example, the rotational speed of a wheel or the longitudinal acceleration of the vehicle. The measured variable can be measured directly, for example, with a sensor. Alternatively or additionally, the measured variable can be determined approximately, for example, using an approximation method as a function of the additional measured variable. The control of the drive motor can then be carried out as a function of the determined additional measured variable. Furthermore, the control of the drive motor can be carried out as a function of the determined additional measured variable and also as a function of the determined angular jerk.Thus, the switching on or off of the support by the drive motor can be carried out both depending on the specific angular jerk and depending on the specific other measured variable.

[0026] This can, for example, further improve accuracy. Alternatively or additionally, the process can be made more reliable, as redundancy can be implemented. This can reduce the vehicle's reliability, availability, and safety.

[0027] According to a further embodiment, determining the additional measured variable involves measuring the torque on the shaft using a torque sensor. The torque sensor can have one or more strain gauges. The shaft can be the crank arm shaft. The torque on the crank arm shaft can be rider torque. Furthermore, determining a first time derivative of the measured torque can be performed using a determining device. The control device can be or include the determining device. Determining the first time derivative can be done using difference quotients or a differentiating low-pass filter, for example, a differentiating IIR or FIR low-pass filter. Controlling the drive motor can then be performed based on the determined first time derivative of the torque.The control of the drive motor, and thus, for example, the switching on or off of the support by the drive motor, can be carried out both as a function of the specific angular jerk and as a function of the specific first time derivative of the torque.

[0028] This allows for redundancy in the control process of the drive motor and its assistance through activation or deactivation. This improves the safety, availability, and reliability of the process and, consequently, the vehicle. This can be advantageous for safety-critical functions, such as the activation or deactivation of the drive motor assistance. Such a method can also reduce the time delay present in conventional methods before the freewheel engages. These conventional methods rely solely on a torque sensor to measure the driver's torque, determine a first time derivative of the driver's torque, and then activate or deactivate the drive motor assistance accordingly. With the method presented here, activation or deactivation can, for example, initially be performed solely based on the defined angular jerk.Within a specific time window, the control of the assistance and the drive motor can then be checked based on the defined first time derivative of the torque. This allows the defined first time derivative of the rider's torque to be used to control the drive motor, specifically to switch the assistance on or off, thereby reducing the time delay between starting pedaling and engaging the freewheel by means of a defined angular jerk.

[0029] Alternatively or additionally, the drive motor can be controlled based on a specific angular jerk and a specific torque. For example, the system first determines whether pedaling has started or stopped based on the specific angular jerk. This determination can then be validated based on the specific torque. With this embodiment, it is possible to quickly detect whether pedaling has started or stopped, depending on the specific angular jerk. Combined with the specified torque, this improves the accuracy of determining whether pedaling has started or stopped.

[0030] Alternatively or additionally, the drive motor can be controlled based on a specific angular jerk and a specific angular acceleration of the shaft. For example, it is first determined, based on the specific angular jerk, whether pedaling has started or stopped. This determination can then be validated based on the specific angular acceleration. In this embodiment, it is possible to quickly detect whether pedaling has started or stopped, depending on the specific angular jerk. Combined with the specific angular acceleration, this improves the accuracy of determining whether pedaling has started or stopped.Angular acceleration, like angular jerk, can be determined as a function of an angular signal and, alternatively or additionally, as a function of an angular velocity. For example, a sensor can be used to determine the angular signal or the angular velocity, and by appropriate differentiation, for example using a differentiating low-pass filter, both the angular acceleration and the angular jerk can be determined. This eliminates the need for a dedicated torque sensor.

[0031] According to another embodiment, the drive motor can be controlled depending on a specific angular jerk when a measuring range of the torque sensor is exceeded. For example, the drive motor can be controlled depending on a specific angular jerk only when, or exactly when, the measuring range of the torque sensor is exceeded. The measuring range can be a predefined area of ​​the torque sensor within which the torque sensor can measure the torque at the shaft with a predefined high confidence level. During control, the assistance can be switched on or off depending on the specific angular jerk when a measuring range of the torque sensor is exceeded.

[0032] This allows, for example, the use of the torque sensor to determine the driver's torque, and the control of the drive motor to be carried out based on the measured driver torque and, alternatively, based on the determined time derivative of the measured driver torque, provided the measuring range is not exceeded. If the measuring range is not exceeded, the torque can be measured with a high level of confidence. If the measuring range is exceeded, the torque can no longer be measured with a high level of confidence. Consequently, the first time derivative of the measured torque can also no longer be determined with a high level of confidence. In this case, the determined angular jerk can be used to control the drive motor instead.This allows the drive motor to be controlled even outside the measuring range of the torque sensor, although the torque sensor itself cannot measure torque with a high degree of confidence. A simpler torque sensor can be used, enabling torque measurement within a specific range. Simultaneously, higher torques, such as those generated by the rider at the crank axle, are possible without requiring direct measurement for control purposes. Instead, the angular jerk can be determined, which correlates at least with the first time derivative of the torque. This allows control even outside the sensor's measuring range.

[0033] According to another embodiment, the drive motor can be controlled based on a specific angular jerk when a defined range of the determining device is exceeded. For example, the drive motor can be controlled based on a specific angular jerk only when, or exactly when, the defined range of the determining device is exceeded. The defined range can be a predefined area of ​​the determining device within which the determining device can determine the first time derivative of the torque at the shaft with a predefined high confidence level. During control, the assistance can be switched on or off based on the specific angular jerk when a defined range of the determining device is exceeded.

[0034] This allows, for example, the determination device to be used to determine the first time derivative of the driver torque, and the control of the drive motor to be carried out based on this determined first time derivative of the driver torque, provided the determination range is not exceeded. If the determination range is not exceeded, the first time derivative of the torque can be determined with a high level of confidence. If the determination range is exceeded, the first time derivative of the torque can no longer be determined with a high level of confidence. For example, outside the determination range, the difference quotient cannot guarantee a determination of the first time derivative of the torque with a high level of confidence. In this case, the determined angular jerk can be used to control the drive motor instead.This allows the drive motor to be controlled even outside the detection range of the measuring device, although the measuring device itself cannot determine the first time derivative of the torque with a high level of confidence. This enables the use of a simple measuring device. For example, a simple algorithm can be used to determine the first time derivative of the torque. Simultaneously, any first time derivative of the torque, such as the rider's torque at the crank axle, can be determined, which does not need to be directly calculated for control purposes. Instead, the angular jerk, which correlates at least with the first time derivative of the torque, can be determined. This allows control to be performed even outside the detection range.

[0035] According to one embodiment, it can be determined whether a fault condition of the torque sensor exists, for example, at least one fault condition. A fault condition can include a failure or malfunction of the torque sensor. Determining whether a fault condition exists can be carried out by means of a device. The device can be the control unit for executing steps of the method. Alternatively or additionally, the device can be the torque sensor itself. Controlling the drive motor can be carried out depending on the specified angular jerk, for example, when, only when, or exactly when a fault condition of the torque sensor exists, for example, at least one fault condition. During control, switching on or off the assistance can be carried out depending on the specified angular jerk if a fault condition exists, for example, at least one fault condition.

[0036] This allows the control to be performed based on a specific angular jerk if the torque sensor malfunctions, for example, if the torque sensor has failed. This increases the reliability of the drive motor control by using the specific angular jerk instead of the torque measured by the torque sensor, or the specific first derivative of the measured torque. This can improve the safety, reliability, and availability of such a vehicle.

[0037] According to a further embodiment, the method can be characterized in that it can be determined whether a fault condition of the determining device exists, for example, at least one fault condition. A fault condition can comprise a failure or malfunction of the determining device. Determining whether a fault condition exists can be carried out by means of a device. The device can be the control unit for executing steps of the method. Alternatively or additionally, the device can be the determining device itself. Controlling the drive motor can be carried out depending on the determined angular jerk, for example, when, only when, or exactly when a fault condition of the determining device exists, for example, at least one fault condition.During steering, the support can be switched on or off depending on the specific angular jerk if an error condition exists, for example, at least one error condition.

[0038] This allows for control to be performed based on the specified angular jerk if the determining device malfunctions, for example, if it has failed. This increases the reliability of the drive motor control by using the specified angular jerk instead of the first time derivative of the measured torque determined by the determining device. This can improve the safety, reliability, and availability of such a vehicle.

[0039] A second aspect of the present invention relates to a drive train for a vehicle. The vehicle can be a bicycle, e-bike, pedelec, or cargo bike that is powered, at least temporarily, by muscle power. The drive train can include a shaft that is accelerated when the vehicle is propelled by a rider. For example, the shaft can be mechanically connected to the crank arm. Crank arms can be non-rotatably connected to the crank arm. For example, two crank arms can be non-rotatably connected to the crank arm, with a pedal rotatably mounted at one end of each crank arm. The crank arm can thus also be referred to as the pedal crank. The crank arm can be rotatably mounted on the vehicle's frame by means of a bearing.The bearing can be a rolling bearing, for example a ball bearing, a needle bearing, or a roller bearing. The pedal crank shaft allows the rider's driving force to propel the vehicle.

[0040] Furthermore, the powertrain may include a drive motor, such as an electric motor, to provide propulsion power to assist the driver in driving the vehicle. The drive motor may be designed to relieve the driver of effort while driving and to increase the vehicle's range. Additionally, the drive motor may be designed to provide propulsion power to relieve the driver.

[0041] The drive train can include a means for determining the angular jerk of the shaft. The drive train can have one or more means for determining the angular jerk. Furthermore, the drive train can include a control device for controlling the drive motor. The assistance provided by the drive motor can be switched on and off depending on the determined angular jerk, either alternatively or additionally.

[0042] This allows the drive train to be configured to switch the relief or support provided by the drive motor on or off depending on the angular jerk of the shaft. Further features, embodiments, and advantages are described in the first aspect. Conversely, features, embodiments, and advantages of the second aspect also represent features, embodiments, and advantages of the first aspect.

[0043] According to a further embodiment, the drive train can be characterized in that the control device can be configured to perform steps of a method according to an embodiment of the first aspect of the present invention. The drive train can be configured to perform all steps of the method according to an embodiment of the first aspect. For example, the means for determining the angular jerk and the control device can be jointly configured to perform all steps of the method according to an embodiment of the first aspect. Furthermore, the drive train can include a torque sensor for measuring a torque on the shaft and a determining device for determining the first time derivative of the measured torque.

[0044] According to a further embodiment, the drivetrain can be characterized in that it includes a sensor for measuring an angular signal of the shaft. The angular signal can be measured as a time-dependent progression, for example, with angular values ​​at equidistant intervals between the individual angular values. The sensor can be configured to measure the crank angle of the crank arms of the pedal crank shaft. The control device can be configured as the means for determining the angular jerk as a function of the measured angular signal. The angular jerk can be determined by approximate triple time differentiation of the angular signal. Thus, the crank angle can be measured using a sensor that is often already present in conventional vehicles. The angular jerk can then be determined based on this measurement.For example, a dedicated sensor for angular jerk is not required. This can reduce the complexity of the drivetrain and thus increase reliability.

[0045] According to a further embodiment, the drive train can be characterized in that it includes a sensor for measuring the cadence of the shaft. The cadence can be measured as a time-dependent progression, for example, with cadence values ​​having time-equidistant intervals between the individual cadence values. The sensor can be configured to measure the cadence of the pedal crank shaft. The cadence can be an angular velocity, for example, the crank angular velocity of the pedal crank shaft. The control device can be configured as the means for determining the angular jerk as a function of the cadence. The determination of the angular jerk can be carried out by approximate two-stage time differentiation of the cadence. The advantages of the previous embodiment also apply to this embodiment.

[0046] The determination of the angular jerk using approximate differentiation can be performed using a numerical method. This determination can be approximate. For example, a numerical method can determine the angular jerk using the difference quotient. Alternatively, a numerical method can determine the angular jerk using a differentiating low-pass filter, such as a differentiating IIR or FIR low-pass filter. For example, the cadence, as a discrete function of time with time-equidistant intervals between the measured cadence values, can be differentiated twice. For this, the difference quotient can be determined twice. Alternatively, the differentiating low-pass filter can be applied twice. In this case, the low-pass filter can be a single-differentiating low-pass filter.Alternatively, a dual-differentiating low-pass filter, such as an IIR or FIR low-pass filter, can be used. This dual-differentiating low-pass filter is applied simply, for example.

[0047] For example, the angle signal can be differentiated three times as a discrete function of time with time-equidistant intervals between the measured values ​​of the angle signal. For this purpose, the difference quotient can be determined three times. Alternatively, the differentiating low-pass filter can be applied three times. This low-pass filter can be a simple differentiating low-pass filter. Alternatively, a triple differentiating low-pass filter, such as an IIR or FIR low-pass filter, can be used. This triple differentiating low-pass filter is applied once. Alternatively, a double differentiating low-pass filter and a simple differentiating low-pass filter can be used. These low-pass filters can be, for example, an IIR and, alternatively or additionally, an FIR low-pass filter.

[0048] A third aspect of the present invention relates to a vehicle with a drive train according to an embodiment of the second aspect of the present invention. The vehicle can be a bicycle, e-bike, pedelec, or cargo bike that is powered, at least temporarily, by muscle power. Further features, embodiments, and advantages of each aspect are described in the first and second aspects, respectively. Conversely, features, embodiments, and advantages of the third aspect also represent features, embodiments, and advantages of the first and second aspects, respectively. Fig. Figure 1 schematically shows the steps of a procedure for controlling the powertrain of a vehicle. Fig. Figure 2 schematically shows a vehicle with a drive train and a control device for executing the schematically described Fig. 1. The steps of the procedure for controlling the powertrain are shown.

[0049] Fig. Figure 1 schematically shows the steps of a procedure for controlling a powertrain 4 of a vehicle 2. Fig. Figure 2 schematically shows such a vehicle 2 with such a drive train 4. The drive train 4 has a shaft 6 which is accelerated by muscle power when the vehicle 2 is propelled by a driver of the vehicle 2. According to one embodiment, the shaft 6 is a pedal crank shaft of the vehicle 2. The pedal crank shaft is rotatably mounted on a frame of the vehicle 2 by means of a bearing. The pedal crank shaft also has pedals (not shown) which are rotatably arranged on crank arms (not shown) of the pedal crank shaft. The bearing is a roller bearing. Furthermore, the drive train 4 has a drive motor 12 for providing propulsion power to assist a driver of the vehicle 2 when propelling the vehicle 2.

[0050] Furthermore, the drive train 4 includes a sensor 13 for measuring S5 an angular signal of the shaft 6. According to one embodiment, the sensor 13 is configured to measure S5 a crank angle of the pedal crank shaft. The sensor 13 is arranged on the frame of the vehicle 2.

[0051] Furthermore, the drive train 4 includes a sensor 14 for measuring S6 of the cadence of the shaft 6. According to one embodiment, the sensor 14 is configured to measure S6 of the cadence of the pedal crank shaft. The sensor 14 is arranged on the frame of the vehicle 2.

[0052] Furthermore, the drive train 4 includes a torque sensor 15 for measuring S3.1 a torque on the shaft 6. According to one embodiment, the torque sensor 15 is configured to measure S3.1 a rider torque on the pedal crank shaft. The torque sensor 15 is arranged on the shaft 6. The torque sensor 15 has at least one strain gauge for measuring S3.1 the torque.

[0053] According to one embodiment, the drive train 4 includes sensor 13 for measuring the angle signal S5, sensor 14 for measuring the cadence S6, and torque sensor 15 for measuring the torque S3.1. In an alternative embodiment, the drive train includes two of the sensors 13, 14, and the torque sensor 15. In another alternative embodiment, the drive train 4 includes either sensor 13 for measuring the angle signal S5, sensor 14 for measuring the cadence S6, or torque sensor 15 for measuring the torque S3.1.

[0054] The drive train 4 also includes a control device 16. The control device 16 is communicatively connected to the sensors 13, 14, the torque sensor 15 and the drive motor 12.

[0055] The drive train 4 further comprises a means for determining S1 of an angular jerk of the shaft 6. The control device 16 is configured as the means for determining S1 of the angular jerk. According to one embodiment, the control device 16 is configured to determine S1 of the angular jerk as a function of the measured angular signal. According to another embodiment, the control device 16 is configured to determine S1 of the angular jerk as a function of the measured cadence.

[0056] The determination of the angular jerk S1 is performed approximately. According to one embodiment, a numerical method is used to determine the angular jerk profile from a measured profile of the angular signal. According to another embodiment, a numerical method is used to determine the angular jerk profile from a measured profile of the cadence. The numerical method is a time differentiation method. Two-fold or three-fold time differentiation is performed by the control device 16. According to one embodiment, two-fold differentiation of the cadence is performed to determine the angular jerk. According to another embodiment, three-fold differentiation of the angular signal is performed to determine the angular jerk. According to another embodiment, both two-fold and three-fold differentiation are performed. This increases the accuracy in determining S1 of the angular jerk.According to one embodiment, either double or triple differentiation is performed. This reduces the computational effort required to determine S1 of the angular jerk.

[0057] The control device 16 is configured to control S2 of the drive motor 12. The assistance provided by the drive motor 12 is switched on or off depending on the specific angular jerk. The control device 16, the sensors 13, 14, and the torque sensor 15 are configured to perform steps of the schematically shown in Fig. to carry out the procedure shown in 1.

[0058] During control operation S2, the assistance provided by the drive motor 12 is activated S2.1 when the defined angular jerk exceeds a first threshold value. Furthermore, during control operation S2, the assistance provided by the drive motor 12 is deactivated S2.2 when the defined angular jerk falls below a second threshold value. In the illustrated embodiment, the magnitude of the first threshold value is greater than the magnitude of the second threshold value. The first threshold value has a positive sign, and the second threshold value has a negative sign. In an alternative embodiment, the magnitude of the first and the magnitude of the second threshold value are identical.

[0059] Furthermore, the control S2 of the drive motor 12 is carried out as a function of a specific additional measured variable. For this purpose, the additional measured variable is determined S3. Measuring S3.1 of the torque at the shaft 6 with the torque sensor 15 is a first step in this process. Next, a first time derivative of the measured torque is determined S3.2 using a measuring device. The control device 16 is configured as the measuring device and performs the determination S3.2 of the first time derivative of the measured torque. The control S2 of the drive motor 12 is then carried out as a function of the determined first time derivative of the torque. This implements redundancy in the procedure. The control S2 of the drive motor 12 as a function of the angular jerk is verified using the determined first time derivative of the measured torque.In an alternative embodiment, the control S2 of the drive motor 12 is performed as a function of the determined first time derivative of the torque, and the control S2 of the drive motor 12 as a function of the determined angular jerk implements redundancy in the control S2. In an alternative embodiment, the control S2 of the drive motor 12 as a function of the angular jerk is verified using the determined torque. In an alternative embodiment, an angular acceleration is determined by differentiating the angular signal twice over time. The control S2 of the drive motor 12 as a function of the angular jerk is then verified using the determined angular acceleration. In an alternative embodiment, the control S2 of the drive motor 12 as a function of the angular jerk is verified using both the determined torque and the determined angular acceleration.

[0060] According to one embodiment, the control S2 of the drive motor 12 is performed depending on the specified angular jerk when a measuring range of the torque sensor 15 is exceeded. The measuring range defines a range in which the measured torque values ​​have a high confidence level. Outside the measuring range, the measured torque values ​​have a lower confidence level. Thus, according to one embodiment, the control S2 is performed depending on the torque measured by the torque sensor 15 and independently of the angular jerk when the measuring range is not exceeded. If the measured torque is outside the measuring range, and therefore the measuring range is exceeded, the control S2 of the drive motor 12 is performed depending on the specified angular jerk and independently of the measured torque.

[0061] According to one embodiment, the control S2 of the drive motor 12 is carried out depending on the determined angular jerk when a determination range of the determining device is exceeded. The determination range defines a range in which the determined values ​​of the first time derivative of the torque have a high confidence level. Outside the determination range, the determined values ​​of the first time derivative of the torque have a lower confidence level. Thus, according to one embodiment, the control S2 is carried out depending on the first time derivative of the torque determined by the determining device and independently of the angular jerk when the determination range is not exceeded.If the determined first derivative of the torque is outside the range of determination and thus the range of determination is exceeded, the control S2 of the drive motor 12 is carried out depending on the determined angular jerk and independently of the determined first time derivative of the torque.

[0062] In one embodiment, a determination S4.1 is performed to ascertain whether a fault condition exists in the torque sensor 15. In another embodiment, the determination S4.1 is performed by the control device 16. This means that the determination S4.1 is performed by an element other than the torque sensor 15, thus reducing its susceptibility to errors. In another embodiment, the determination S4.1 is performed using the torque sensor 15, thus reducing the requirements for the control device 16. In yet another embodiment, the determination S4.1 is performed by both the control device 16 and the torque sensor 15. In yet another embodiment, either the determination S4.1 is performed by the control device 16 or by the torque sensor 15. A fault condition includes both a simple fault of the torque sensor 15, such as incorrect calibration, and a complete failure of the torque sensor 15.If a fault condition exists, the control S2 of the drive motor 12 is performed depending on the specified angular jerk. According to one embodiment, the control S2 is performed depending on the first time derivative of the measured torque and independently of the specified angular jerk if no fault condition of the torque sensor 15 exists. If a fault condition of the torque sensor 15 exists, the control S2 is performed independently of the specified first time derivative of the measured torque and depending on the specified angular jerk.

[0063] In one embodiment, a determination S4.2 is performed to ascertain whether a fault condition of the determining device exists. In another embodiment, the determination S4.2 is performed by a device other than the control device 16 as the determining device. This increases safety. In another embodiment, the determination S4.2 is performed using the control device 16 as the determining device. This eliminates the need for a separate device to determine S4.2 of a fault condition of the determining device. In another embodiment, the determination S4.2 is performed by both the other device and the control device 16. In yet another embodiment, the determination S4.2 is performed either by the other device or by the control device 16.An error state includes both a simple error in the measuring device, such as an incorrect implementation of an algorithm for determining S3.2 the first time derivative of the torque, and a failure of the measuring device. If an error state of the measuring device exists, the control S2 of the drive motor 12 is performed depending on the determined angular jerk. According to one embodiment, if no error state of the measuring device exists, the control S2 is performed depending on the first time derivative of the measured torque and independently of the determined angular jerk. If an error state of the measuring device exists, the control S2 is performed independently of the determined first time derivative of the measured torque and depending on the determined angular jerk.

[0064] According to one embodiment, the control S2 is carried out independently of the measured torque and independently of the determined first time derivative of the measured torque and depending on the determined angular jerk, if a fault condition of the torque sensor 15 and alternatively or additionally of the determining device is present.

[0065] With such a method and such a drive train 4, precise and rapid detection and determination of the rider's pedaling in vehicle 2 is made possible. Thus, the method and the drive train 4 are configured to detect and determine pedaling more accurately and quickly than known methods and drive trains that detect pedaling solely based on measuring the rider's torque at the crank arm 6 and determining the first time derivative of the measured rider torque. This increases safety when using vehicle 2 with such a drive train 4, which is controlled by such a method.The switching on or off of the support by the drive motor 12 is thus carried out faster compared to known methods and drive trains, which switch the support on or off only based on the determined first time derivative of the measured driver torque. Reference sign 2 vehicles 4 Powertrain 6 wave 12 Drive motor 13 Sensor for measuring an angular signal of the shaft 14 Sensor for measuring the cadence of the wave 15 Torque sensor 16 Control device S1 Determining an angular jerk of the shaft S2 Controlling the drive motor S2.1 Activating support from the drive motor S2.2 Switching off support from the drive motor S3 Determining another measured variable on the powertrain S3.1 Measuring a torque on the shaft S3.2 Determining a first time derivative of the measured torque using a determining device S4.1 Determine if a fault condition of the torque sensor exists S4.2 Determine whether a fault condition exists in the determining device S5 Measuring the angle signal of the wave S6 Measuring the cadence of the wave

Claims

[1] Method for controlling a drive train (4) of a vehicle (2), wherein the drive train (4) has at least one shaft (6) which is accelerated when the vehicle (2) is driven by a driver, wherein the drive train (4) has a drive motor (12) for providing drive power to assist the driver of the vehicle (2) when driving the vehicle (2), wherein the method comprises the steps: determining (S1) an angular jerk of the shaft (6); and controlling (S2) the drive motor (12), wherein the assistance provided by the drive motor (12) is switched on or off depending on the determined angular jerk. [2] Method according to claim 1, characterized by , that when controlling (S2) an activation (S2.1) of the support by the drive motor (12) is carried out when the certain angular jerk exceeds a first threshold value. [3] Method according to any one of the preceding claims, characterized by, that during control (S2) a switching off (S2.2) of the support by the drive motor (12) is carried out if the certain angular jerk falls below a second threshold value. [4] Method according to any one of the preceding claims, characterized by , that a determination (S3) of a further measured variable is carried out on the drive train (4), and that the control (S2) of the drive motor (12) is carried out depending on the determined further measured variable. [5] Method according to claim 4, characterized by , that in determining (S3) the further measured quantity a measurement (S3.1) of a torque on the shaft (6) is carried out with a torque sensor (15), that a determination (S3.2) of a first time derivative of the measured torque is carried out with a determining device and that the control (S2) of the drive motor (12) is carried out depending on the determined first time derivative of the torque. [6] Method according to claim 5, characterized by , that the control (S2) of the drive motor (12) is carried out depending on the specific angular jerk when a measuring range of the torque sensor (15) is exceeded. [7] Method according to one of claims 5 or 6, characterized by , that the control (S2) of the drive motor (12) is carried out depending on the determined angular jerk when a determination range of the determination device is exceeded. [8] Method according to any one of claims 5 to 7, characterized by , that a determination (S4.1) is carried out to determine whether a fault condition of the torque sensor (15) exists, and that the control (S2) of the drive motor (12) is carried out depending on the determined angular jerk if a fault condition of the torque sensor (15) exists. [9] Method according to any one of claims 5 to 8, characterized by, that a determination (S4.2) is carried out to determine whether a fault condition of the determining device exists, and that the control (S2) of the drive motor (12) is carried out depending on the determined angular jerk if a fault condition of the determining device exists. [10] Drive train (4) for a vehicle (2), wherein the drive train (4) has at least one shaft (6) which is accelerated when the vehicle (2) is driven by a driver, wherein the drive train (4) has a drive motor (12) for providing drive power to assist the driver of the vehicle (2) when driving the vehicle (2), wherein the drive train (4) has a means for determining (S1) an angular jerk of the shaft (6), and wherein the drive train (4) has a control device (16) for controlling (S2) the drive motor (12), wherein the assistance by the drive motor (12) is switched on or off depending on the determined angular jerk. [11] Drive train (4) according to claim 10, characterized by , that the control device (16) is configured to perform steps of a method according to any one of claims 1 to 9. [12] Drive train (4) according to one of claims 10 or 11, characterized by , that the drive train (4) has a sensor (13) for measuring (S5) an angular signal of the shaft (6) and that the control device (16) is set up as the means for determining (S1) the angular jerk as a function of the measured angular signal. [13] Drive train (4) according to any one of claims 10 to 12, characterized by , that the drive train (4) has a sensor (14) for measuring (S6) a cadence of the shaft (6) and that the control device (16) is set up as the means for determining (S1) the angular jerk as a function of the measured cadence. [14] Vehicle (2) with a drive train (4) according to any one of claims 10 to 13.

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