Method for controlling a torque assist of a drive unit of a vehicle

Abstract

The invention relates to a method for controlling a torque assist of a drive unit of a vehicle, in particular a single-track vehicle such as an e-bike. The torque assist is based partly on a a system model and partly on a boosting of a pedaling torque by an assist factor, said pedaling torque being provided by an operator, wherein the assist factor is determined on the basis of the pedaling torque, in particular in a progressive manner, and the system model is based at least on the speed and / or acceleration of the vehicle and a compensation for disturbance variables, in particular an incline and frictional resistance.

Description

[0001] Description

[0002] title

[0003] Method for controlling torque support of a drive unit of a vehicle

[0004] The invention relates to a method for controlling a torque assistance of a drive unit of a vehicle, in particular a single-track vehicle such as an eBike, a pedelec or the like.

[0005] The invention further relates to a vehicle, in particular a single-track vehicle such as an eBike, pedelec or the like, with a drive unit, wherein the drive unit is designed to amplify a pedal torque by means of a controlled torque assistance.

[0006] Although the present invention is applicable to any vehicle, the present invention will be explained with reference to eBikes.

[0007] State of the art

[0008] E-bikes can provide torque assistance to a rider to increase pedaling torque, for example, when climbing an incline. Using a suitable system model, which forms the basis for determining the amount of torque assistance, external disturbances such as wind or incline can be compensated for by the torque assistance.

[0009] However, the calculation of the disturbance effects is slow, as the necessary speeds and / or accelerations can only be determined with a delay. Therefore, if a rider suddenly requires increased torque, for example, when at the beginning of a climb, the torque assistance initially provides too little torque. This impairs the rider's driving experience.

[0010] Disclosure of the invention

[0011] In one embodiment, the present invention provides a method for controlling torque assistance of a drive unit of a vehicle, in particular a single-track vehicle such as an e-bike, wherein the torque assistance is based on a component of a system model and a component of an amplification of a pedal torque provided by a rider by an assistance factor, wherein the assistance factor is determined, in particular progressively, depending on the pedal torque, and wherein the system model is based at least on a speed and / or acceleration of the vehicle and a compensation of disturbance variables, in particular a gradient, mass inertia, and frictional resistance. As a disturbance variable, mass inertia plays a special role in the application of the method for controlling torque assistance of a drive unit of a cargo bike.Due to the sometimes high payload, mass inertia plays a special role.

[0012] In one embodiment, the present invention provides a vehicle, in particular a single-track vehicle such as an eBike, with a drive unit, wherein the drive unit is designed to amplify a pedal torque by means of a controlled torque assistance, wherein the torque assistance is based on a proportion of a system model and a proportion of an amplification of the pedal torque provided by a rider by an assistance factor, wherein the assistance factor is determined as a function of the pedal torque and wherein the system model is based at least on a speed and / or acceleration of the vehicle and a compensation of disturbance variables, in particular a gradient, a mass inertia and a frictional resistance.The advantage of this is that the interaction of the system model and the amplification of the pedal torque by a certain assistance factor allows for rapid response to changing torque requirements, while simultaneously compensating for longer-term disturbances such as gradients, mass inertia, or air resistance. This allows for fast and precise control of the torque assistance. Furthermore, the control can also be adapted to the rider's individual needs, for example, by simulating an artificial tailwind with the torque assistance.

[0013] The term "system model" is understood, particularly in the description, preferably in the claims, to mean a model with which the driving behavior of the vehicle can be described. The system model describes an idealized or specifiable driving style, for example, driving on a flat surface at 20 km / h. From this, a specifiable, required, or idealized pedal torque is then determined. If the actual pedal torque differs from the idealized pedal torque, i.e., additional disturbances influence the vehicle, the residual torque can be compensated by the torque support of the drive unit. The system model can take the form

[0014] M * v + D * v + g = Q * f h + a * g. Here, M describes a predetermined mass of the vehicle, v an acceleration of the vehicle, D a friction coefficient of the vehicle, v a speed of the vehicle, g disturbances such as a gradient, Q the assistance factor, fh the pedal torque, a a component factor for the disturbance compensation, and g the disturbance compensation. The left side of the equation thus describes forces that must be overcome by the vehicle—for example, acceleration, friction, gradient—and the right side describes what generates the required forces—for example, pedal torque, torque assistance from a drive, disturbance compensation.

[0015] The amplification factor Q depends on the pedal torque f h , that is, Q = Q(fh). Consequently, when the pedal torque f h a part of the drive torque Q * f hincreased disproportionately. Thus, the torque assistance is reactive and can respond quickly to changing torque requirements because, when the rider increases pedaling torque, the torque assistance is directly increased due to the disproportionate relationship between the gain factor and pedaling torque.

[0016] The pedal torque is defined in particular as the portion of a total torque acting on the vehicle that is provided by the driver, in particular generated by the driver pedaling.

[0017] The compensation of one or more disturbances, also referred to below as disturbance compensation, describes a process in which disturbances such as a gradient, mass inertia or air resistance, which influence the driving behavior of the vehicle, are compensated for by torque assistance. If, for example, the vehicle is driving uphill, i.e. the required total drive torque is increased due to the gradient, this influence is compensated for by an increase in torque assistance, i.e. the disturbance is "compensated for". A driver of the vehicle therefore perceives the driving behavior as if the disturbance did not exist. The magnitude of the disturbance compensation, i.e. the magnitude of the torque required to compensate for all disturbances, can vary over time.A disturbance compensation rate of change is defined as the time change, in particular the first derivative, of the total torque used to compensate for the disturbances.

[0018] Further features, advantages and further embodiments of the invention are described below or will become apparent thereby.

[0019] In one embodiment of the method according to the invention, the component of the system model and the component of the amplification of a pedal torque provided by a rider are coordinated by an assistance factor in such a way that, at a high pedal torque, the component of the amplification provides a high assistance factor until the component of the system model reduces the pedal torque to such an extent that a low assistance factor or essentially no assistance factor is provided. "Essentially no assistance factor" here means that the assistance factor is essentially zero. Among other things, it is possible to ride essentially completely without motor assistance in the event of minor disturbances.

[0020] In a further embodiment, the assistance factor is determined, in particular progressively, depending on the pedal torque in such a way that in a range below a threshold value of the pedal torque the assistance factor is substantially constant, in particular zero, and in a range above the threshold value the assistance factor increases progressively depending on the pedal torque.

[0021] According to an advantageous development of the invention, the system model is based on a predetermined mass of the vehicle and / or the driver. This improves the reliability of the system model. The predetermined mass of the vehicle may differ from the actual weight of the vehicle and the driver. This allows a different vehicle weight to be simulated. For example, the model weight may correspond to the weight of the vehicle and driver without an attached load. In this way, the weight of the attached load can be viewed as a disturbance variable that is compensated for by the torque assistance in the system model. The vehicle can then behave as if no load were attached.

[0022] According to an advantageous development of the invention, the predetermined mass of the vehicle is determined depending on the speed of the vehicle. The advantage of this is that the driving behavior of the vehicle can be adapted to different speeds. For example, the predetermined mass of the vehicle can be higher at low speeds, thus enabling easier handling of the vehicle. It is also possible to reduce the predetermined mass of the vehicle when the vehicle is stationary in order to enable easier starting. In other words, in the above-mentioned equation of the system model M = M(v). According to an advantageous development of the invention, the system model is based on a model gradient and / or a friction value, in particular an air friction value and / or a rolling friction value. The friction value represents speed-dependent friction effects of the vehicle.This allows for better compensation of friction effects and / or adjustment by the driver. The gradient of the terrain is not taken into account in the system model equation and is therefore considered a disturbance factor that is compensated for by the torque assistance provided by the system model. Thus, when driving uphill, a driver has the same driving experience as when driving on level ground. Because the system model is based on a model gradient, the influence of the gradient on driving behavior is at least partially retained. For this purpose, a sensor can be installed to determine the vehicle's gradient. It is also possible to simulate or specify a constant gradient for training purposes.

[0023] According to an advantageous development of the invention, the friction value is determined as a function of the speed of the vehicle, in particular wherein the friction value is determined sub-proportionately to the speed of the vehicle. Since the friction losses are not modeled as a disturbance variable in the system model and are therefore not compensated by the torque assistance, the required pedaling torque increases with an increase in speed. Due to the speed-dependent friction value, which is in particular sub-proportionate, the required pedaling torque only increases proportionally with an increase in speed. For example, with an inverse dependency D = D(1 / v), the friction loss would be independent of the speed of the vehicle. This provides the driver with a pleasant driving experience at high speeds.

[0024] According to an advantageous development of the invention, the system model is based on a model wind. Using a model wind, an artificial tailwind and / or headwind can be simulated in the system model. This can improve the driving experience for the driver. The model wind can, for example, be in the form D * (v - v wind) are included in the system model. According to an advantageous development of the invention, the part of the system model is filtered by a filter, in particular a low-pass filter. The disturbance variable compensation can be based on a speed and an acceleration of the vehicle. Since these values ​​may not be measured continuously, the determined speed and acceleration values ​​can fluctuate around a mean value, which leads to varying, in particular abruptly changing, torques which could damage the drive unit or at least place severe strain on it. These fluctuations can be compensated for by a filter, in particular a low-pass filter, preferably a first-order low-pass filter. The advantage is that the torque assistance can be more uniform, which improves the driver experience.

[0025] According to an advantageous development of the invention, the component of the system model is filtered depending on a rate of change of the disturbance compensation. For example, the strength of the filter can be influenced by changing a time constant of the filter. In particular, the time constant of the filter can be smaller for a negative rate of change of the disturbance compensation than the time constant of the filter for a positive rate of change of the disturbance compensation. The strength of the filter is thus higher when the torque support for disturbance compensation increases and lower when the torque support for disturbance compensation decreases. The time constant of the filter can delay peaks in the torque support, so that the torque support is less noisy and / or fluctuating. However, the filter can slow the reactivity of the torque support.For example, this can enable the torque assistance to still provide a high torque when driving over the crest of a hill, even though this is not desired. Because the time constant of the filter is dependent on the rate of change of the disturbance compensation, in particular the first derivative of the disturbance compensation, the reactivity of the torque assistance can, for example, be greater at the crest of the hill than at the beginning of the hill. This prevents "overshooting", i.e. the provision of too high a torque when driving over the apex of the hill. The proportion of torque assistance from the system model thus advantageously increases more slowly than it decreases. According to an advantageous development of the invention, system parameters of the system model, in particular the predetermined mass of the vehicle, the friction value, the model gradient and / or the model wind, can be adjusted by a user.This allows the driving behavior to be adapted to the driver's wishes, for example by setting a tailwind or a constant gradient.

[0026] According to an advantageous development of the invention, the assistance factor is determined depending on the rate of change of the pedaling torque. The rate of change of the pedaling torque can, in particular, be the first derivative of the pedaling torque. This allows sudden changes in the torque assistance to be reduced.

[0027] Further important features and advantages of the invention emerge from the subclaims, from the drawings and from the associated description of the figures.

[0028] It is understood that the features mentioned above and those to be explained below can be used not only in the combination specified in each case, but also in other combinations or on their own, without departing from the scope of the present invention.

[0029] Preferred embodiments and embodiments of the present invention are illustrated in the drawings and are explained in more detail in the following description, wherein the same reference numerals refer to the same or similar or functionally identical components or elements.

[0030] This shows

[0031] Figure 1 shows in schematic form a method according to an embodiment of the present invention;

[0032] Figure 2 shows, in schematic form, a curve of a torque assistance factor according to an embodiment of the present invention; and Figure 3 shows, in schematic form, a single-track vehicle according to an embodiment of the present invention.

[0033] Figure 1 shows in schematic form a method according to an embodiment of the present invention.

[0034] Figure 1 shows a control system for torque assistance of a single-track vehicle 101 with a drive unit 102. The torque assistance is based on a system model 103 and an amplification of a pedal torque provided by a rider (not shown). For this purpose, an idealized riding situation is first simulated, and the required pedal torque in the idealized case is determined. In the idealized riding situation, disturbing effects such as air resistance and gradients are not taken into account. The required pedal torque multiplied by a constant assistance factor 105 then corresponds to the required total torque in the idealized riding situation.

[0035] If the actual pedaling torque applied by the rider is greater than the idealized pedaling torque, a disturbance compensation factor 104 is determined using the system model 103. Based on the disturbance compensation factor 104, the assistance torque of the drive unit 102 is adjusted so that the rider only needs to apply the pedaling torque determined from the idealized riding situation to maintain a desired speed. The assistance factor 105 is constant in this case.

[0036] The determination of the disturbance compensation 104 by the system model 103 is based on the speed and / or acceleration of the vehicle. If the vehicle's speed is determined, for example, via a sensor on a wheel, the speed can only be determined for each complete revolution of the wheel. The acceleration of the vehicle can be calculated from the speed. Thus, the determination of the disturbance compensation 104 is sluggish and cannot be calculated in real time. Sudden changes in the required pedaling torque cannot be immediately compensated for by the disturbance compensation 104. To compensate for this delay, the assistance factor 105 is based on the pedaling torque. Figure 2 shows, in schematic form, a curve of a pedaling torque assistance factor according to an embodiment of the present invention.

[0037] Figure 2 shows a diagram 201 of a curve 202 of a pedal torque assistance factor. The X-axis 203 shows the pedal torque generated by a rider in any unit, and the Y-axis 204 shows the dimensionless pedal torque assistance factor. The curve 202 is divided into two areas: a continuous area 205 in which the assistance factor is approximately constant, and a "kickdown" area 206 in which the assistance factor increases approximately linearly.

[0038] The torque assistance is based on two components, a disturbance compensation, for example a compensation of a gradient, by the system model and a pedal torque assistance, characterized by an assistance factor.

[0039] When a rider is riding on a flat surface 207, the system model compensates for any gradient influence, and the assistance factor is low. Thus, the bicycle's drive unit is in the steady-state zone 205. As soon as the rider reaches a gradient transition zone 207', the gradient influence increases rapidly. However, the system model's disturbance compensation is sluggish, so the rider must pedal hard to maintain speed. To minimize this effect, the assistance factor is progressively dependent on the pedaling torque, for example, linearly. When the pedaling torque increases sharply, the bicycle's drive unit is in the kickdown zone 206, and the assistance factor increases. The required increase in torque due to the gradient is thus at least partially compensated for by the higher torque assistance due to the higher assistance factor.Once the rider has ridden the increased incline for sufficient time and is in a steady range of 207" of the incline, the influence of the incline is again compensated for by the disturbance compensation of the system model, and the rider's pedaling torque decreases. Thus, the assistance factor also decreases and is constant again because the bicycle's drive unit is once again in the steady range of 205. Figure 3 shows a schematic of a single-track vehicle according to an embodiment of the present invention.

[0040] Figure 3 shows a single-track vehicle 101 with a drive unit 102. The vehicle can be an e-bike. The drive unit 102 is configured to amplify pedaling torque through controlled torque assistance, wherein the torque assistance is based on a system model with an amplification of the pedaling torque provided by a rider (not shown) by an assistance factor, wherein the assistance factor is based on the pedaling torque, and wherein the system model is based at least on a speed and / or acceleration of the single-track vehicle 101 and a compensation for disturbances.

[0041] To determine the actual pedal torque provided by a rider, a torque sensor can be arranged on the drive unit 102 and / or on the vehicle 101. The speed of the vehicle 101 can be measured via a speed sensor 304. The acceleration of the vehicle can be determined from the speed and / or determined by an acceleration sensor 305. A gradient sensor 306 can optionally measure the gradient of a surface in order to incorporate the gradient into the system model.

[0042] In summary, at least one embodiment of the present invention has at least one of the following features and / or provides at least one of the following advantages:

[0043] Fast response to changing torque requirements

[0044] Pleasant driving experience for a driver

[0045] Individual adjustment of torque support

[0046] Although the present invention has been described using preferred embodiments, it is not limited thereto but can be modified in many ways.

Claims

Claims 1. Method for controlling a torque support of a drive unit (102) of a vehicle (101), in particular a single-track vehicle such as an e-bike, wherein the torque support is based on a component of a system model (103) and a component of an amplification of a pedaling torque provided by a rider by a support factor (105), wherein the support factor (105), in particular progressively, is determined depending on the pedaling torque and wherein the system model (103) is based at least on a speed and / or acceleration of the vehicle (101) and a compensation (104) of disturbance variables, in particular a gradient, a mass inertia and a frictional resistance.

2. Method according to claim 1, wherein the component of the system model (103) and the component of the amplification of a pedaling torque provided by a rider by a support factor (105) are coordinated such that, by the component of the amplification, a high support factor (105) is provided at a high pedaling torque until, by the component of the system model (103), the pedaling torque becomes so low that a low support factor (105) or substantially no support factor (105) is provided.

3. Method according to claim 1 or 2, wherein the support factor (105), in particular progressively, is determined as a function of the pedaling torque such that in a range below a threshold value of the pedaling torque the support factor (105) is essentially constant, and in a range above the threshold value the support factor (105) increases progressively as a function of the pedaling torque.

4. Method according to one of the preceding claims, wherein the system model (103) is based on a predetermined mass of the vehicle (101) and / or the driver. A method according to claim 4, wherein the predetermined mass of the vehicle is determined as a function of the vehicle's speed (101). A method according to any of the preceding claims, wherein the system model (103) is based on a model gradient and / or a friction coefficient, in particular an air friction coefficient and / or a rolling friction coefficient. A method according to claim 6, wherein the friction coefficient is determined as a function of the vehicle's speed (101), in particular wherein the friction coefficient is determined less than proportionally to the vehicle's speed (101). A method according to any of the preceding claims, wherein the system model (103) is based on a model wind. A method according to any of the preceding claims, wherein the component of the system model is filtered by a filter, in particular a low-pass filter.A method according to claim 9, wherein the proportion of the system model is filtered depending on a rate of change of the compensation of disturbance variables. A method according to any of the preceding claims, wherein system parameters of the system model (103), in particular the predefined mass of the vehicle, the coefficient of friction, the model gradient and / or the model wind, are adjustable by a user. A method according to any of the preceding claims, wherein the support factor (105) is determined depending on a rate of change of the pedaling torque. A vehicle, in particular a single-track vehicle such as an e-bike, with a. drive unit (102), wherein the drive unit (102) is configured to a to amplify pedaling torque by means of a controlled torque support, wherein the torque support is based on a component of a system model (103) and a component of an amplification of the pedaling torque provided by a rider by a support factor (105), wherein the support factor (105) is determined depending on the pedaling torque and wherein the system model (103) is based at least on a speed and / or acceleration of the vehicle (101) and a compensation (104) of disturbances, in particular a gradient and frictional resistance.

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