Flywheel mass-free bicycle ergometer

Abstract

The invention relates to a bicycle ergometer (10) comprising: a crankset (16) with pedals (18); an electric machine (22) which is drivingly connected to the crankset (16); a power supply (24) for operating the bicycle ergometer (10); a motor control unit (26) for controlling the electric machine (22) on the basis of motor control signals; and an ergometer control unit (28) for generating the motor control signals, wherein the bicycle ergometer (10) is designed to be free of a flywheel mass; and the motor control unit (26) is designed to control the electric machine (22) on the basis of the motor control signals in order to generate a defined torque and / or a defined rotational speed on the crankset (16). The invention also relates to a method for controlling a bicycle ergometer and to a corresponding computer program product.

Description

[0001] Rhineland-Palatinate University of Technology Kaiserslautern-Landau

[0002] Flywheel-free bicycle ergometer

[0003] The present invention relates to a bicycle ergometer, in particular a flywheel-free bicycle ergometer, a method for controlling a bicycle ergometer and a corresponding computer program product.

[0004] Ergometers, especially bicycle ergometers, are well-known and play a central role in medicine, especially cardiology, in physical therapy, and rehabilitation. Ergometers are also known as training devices for private individuals and / or professional athletes. Common ergometers are based on bicycles in their design and mechanics, although they are primarily used indoors and do not generate any propulsion. In this respect, they serve purely as exercise equipment.

[0005] Newer models, especially those aimed at athletic users, are usually based on current trends and training methods from the cycling world. Nevertheless, ergometers differ significantly in their use from training with a bicycle.

[0006] This also means that users sometimes have to force themselves to use the bike regularly. Consequently, demotivation quickly sets in with traditional ergometers. Conventional ergometers usually consist of a flywheel and a brake, which can be mechanical or magnetic, connected to a freewheel by a chain or belt with a pedal crank.

[0007] Also known are so-called spinning bikes, which usually have a larger flywheel compared to traditional ergometers and a mechanical brake. On spinning bikes, the flywheel and brake are connected to the pedal crank without a freewheel.

[0008] It's also common to use classic bicycles, especially racing bikes, in conjunction with so-called roller trainers or brakes. In this case, the rear wheel of the bicycle drives a braked roller, allowing the bicycle to be used indoors without moving.

[0009] All of the ergometers mentioned above generate their riding and training behavior purely mechanically. Therefore, they are only slightly dynamically adjustable.

[0010] Furthermore, all of the above-mentioned solutions involve purely concentric training, in which leg strength must always be applied in the direction of movement.

[0011] In particular, it is known that braked devices in particular create an unnatural and particularly demotivating feeling of constantly climbing uphill.

[0012] To partially mitigate this, it is known to use several braking elements in order to be able to recreate different load simulations.

[0013] All of the aforementioned ergometers have limitations due to their mechanical design. In particular, concentric training can be performed with each of the aforementioned ergometers. The unnatural feeling they convey leads to demotivation and inadequate training, as they can only inadequately replicate a real bicycle ride. Therefore, there is a need to provide an improved ergometer.

[0014] Against this background, the present invention achieves the object of providing an improved ergometer that overcomes at least one of the aforementioned disadvantages. In particular, an ergometer is to be created that conveys a realistic riding experience and, in particular, can better replicate a real bicycle ride. In a particularly preferred embodiment, an ergometer with the option of gamification is to be created.

[0015] This object is achieved by a bicycle ergometer with: a rotating load element, for example a pedal crank with pedals; an electrical machine which is connected to the pedal crank in a driving manner, in particular directly, i.e. without a freewheel; preferably an energy supply for operating the bicycle ergometer, which is particularly preferably designed to be bidirectional, for example a mains connection, an electrical energy store; alternatively, an electrical load and / or an electrical source can be used; a motor control unit for controlling the electrical machine based on motor control signals; an ergometer control unit for generating the motor control signals; wherein the bicycle ergometer is designed to be as flywheel-free as possible.and the motor control unit is designed to control the electric machine based on the motor control signals in order to generate a predefined, in particular precalculated, torque and / or a predefined, in particular precalculated, speed at the pedal crank.;

[0016] The above object is further achieved by a method for controlling a bicycle ergometer, in particular a bicycle ergometer as defined above, comprising the steps:

[0017] Detecting a torque and / or a speed at the crank;

[0018] Calculating a torque and / or a speed to be applied to the pedal crank based on a predetermined training mode; and

[0019] Controlling the electric machine to apply the required torque and / or speed to the pedal crank.

[0020] The above object is further achieved by a computer program product having program code for carrying out the steps of the method when the program code is executed on a computer, as well as a storage medium on which a computer program is stored which, when executed on a computer, effects execution of the method described herein.

[0021] Preferred embodiments of the invention are described in the dependent claims. It is understood that the features mentioned above and those to be explained below can be used not only in the respective combination specified, but also in other combinations or on their own, without departing from the scope of the present invention. In particular, the bicycle ergometer, in particular the control unit of the bicycle ergometer, can be designed according to the embodiments described for the method in the dependent claims. The ergometer according to the invention is similar to a previously known ergometer, whereby in known ergometers inertia, in particular in the form of a flywheel, is introduced into a drive train. In the present case, diametrically opposed to this, it is proposed to keep the inertia mechanically introduced into the drive train low.In particular, the bicycle ergometer preferably has no additional mechanical load or brake. According to the invention, the flywheel and / or the brake can be replaced by the electric machine without a freewheel. It is understood that freewheeling can also be simulated by advantageously controlling the electric machine. Within the scope of the invention, it was determined that the mechanical design of a bicycle ergometer has disadvantages. To overcome these disadvantages, it was recognized that, instead of the classic ergometer design, a comparatively low-mass ergometer, in particular one with low inertia and flywheel mass, which comprises an electric machine that can be advantageously controlled, enables individual and more realistic training.The electric motor is controlled in such a way that it applies a torque and / or speed to the pedal crank that essentially corresponds to the torque and / or speed during a real ride. It is understood that the power supply of the bicycle ergometer can also be designed to absorb energy generated by the electric motor during operation.

[0022] In the context of the present invention, flywheel-free can mean, for example, that in addition to the natural inertia of components of the drive train that are essential for the remaining behavior, for example electrical machines, bearings, pedals, gears, belts, rollers, no additional inertial mass, such as flywheels, is introduced, which in particular does not serve any further function of its own besides the function of inertia and / or a brake (for example mechanically or possibly via eddy current, as established in conventional ergometers). Preferably, the inertia of the essential parts is not higher than a person skilled in the art would envisage for the remaining functions, at least not by more than 100%, particularly preferably not by more than 50% or more than 25% higher than absolutely necessary to provide the necessary functions without inertia with high mechanical reliability and robustness.

[0023] Flywheel-free can alternatively mean in particular that no mass discs, even those with a secondary function, for example as a motor shaft, crankshaft, gear, roller or the like, with more than 25 kg, preferably more than or equal to 10 kg, particularly preferably more than or equal to 7 kg, are introduced.

[0024] Flywheel-free can also mean that there is no flywheel with an inertia of more than 1000 kg cm 2 , preferably more than or equal to 500 kg cm 2 , particularly preferably more than or equal to 250 kg cm 2 or more than or equal to 150 kg cm 2 is installed in a rotating connection with the pedals.

[0025] Alternatively, flywheel-free can also mean that no flywheel is coupled with a mechanical transmission to the pedals and / or other parts of the drive, in order to use a smaller flywheel at a higher speed. For example, flywheel-free can then mean that effectively less than 1000 kg cm 2 after diversion with the quadratic transmission ratio, preferably less than 500 kg cm 2 after diversion with the quadratic transmission ratio, particularly preferably less than 250 kg cm 2 or less than or equal to 150 kg cm 2 after diversion with the quadratic transmission ratio on the pedal shaft.

[0026] For this purpose, the bicycle ergometer has, on the one hand, a motor control unit for controlling the electric machine and an ergometer control unit for generating motor control signals for the motor control unit. This logical separation of the two control units serves to better understand the invention. A person skilled in the art will recognize that both control units can be implemented on a single circuit board or in a single circuit. It is understood that a corresponding motor control unit can also be integrated as a separate component, for example, into the electric drive motor. By applying a predefined torque and / or a predefined speed, the predefined torque and / or speed can be precalculated, whereby various individual training modes can be mapped with the bicycle ergometer according to the invention.The described design of a bicycle ergometer allows for the creation of a lightweight and compact ergometer. In particular, a bicycle ergometer can be created that can be stored in a space-saving manner when not in use.

[0027] In a preferred embodiment, the pedal crank is connected to the electric motor via a traction drive, preferably a belt. This allows for a direct connection between the pedal crank and the electric motor to be established in a technically simple manner. Furthermore, this design allows for a high degree of flexibility in the arrangement of the electric motor. This allows the individual elements of the bicycle ergometer to be advantageously mounted on the bicycle ergometer.

[0028] In a further advantageous embodiment, the electric motor is connected to the pedal crank via a spur gear and / or a planetary gear. A connection via a spur gear or planetary gear enables, on the one hand, a high compactness of the bicycle ergometer. On the other hand, the use of a gear enables the establishment of a high gear ratio, so that a correspondingly smaller-sized electric motor can be used. Furthermore, spur gear and / or planetary gear are mechanically robust, thus increasing the reliability of the bicycle ergometer.

[0029] In a preferred embodiment, the motor control unit is designed to actively and preferably dynamically control the electric motor in two quadrants, preferably in four quadrants. Active dynamic control of the electric motor enables advantageous, customized and highly variable training with the bicycle ergometer. Control in two or four quadrants allows comprehensive control of the electric motor. A corresponding torque can be created for each angular position of the pedal crank, so that training can take place at any angular position of the pedal crank.

[0030] In a preferred embodiment, the ergometer control unit is designed to set up at least one of the following training modes:

[0031] Inertia with freewheel, which preferably corresponds to a classic ergometer;

[0032] Inertia without freewheel, corresponding to a spinning bike, fixed-gear bike, or fixie bike; a bicycle physics model with elevation and / or route profile without freewheel, corresponding to a type of fixie bike on a pump track; a bicycle physics model with elevation and / or route profile with freewheel, corresponding to a mountain bike, racing bike, or in particular a classic bicycle; and / or an eccentric load situation in which the direction of force is opposite to the direction of muscle movement in order to achieve muscle training effects, particularly in contrast to cardiovascular training.

[0033] This makes it possible to create a multifunctional training device suitable for both professional and recreational athletes. Through various modes, which a user can preferably set on the bicycle ergometer control unit, the corresponding motor control signals can be precalculated. These signals are then transmitted by the motor control unit to the pedal crank via the electric motor.

[0034] For adjustment purposes, the bicycle ergometer can include a control display, as is already known in the art. It goes without saying that other control options are also conceivable; for example, the bicycle ergometer could be controlled via an app, allowing a smartphone to be used advantageously as a display and control unit.

[0035] Since the drive train is designed to have as little inertia as possible, the aforementioned operating modes can be realistically simulated. To calculate the various training modes, the torque applied to the crank by the user and / or the speed can be recorded, for example, using the motor currents, the motor voltages, and / or a torque / speed sensor. Furthermore, a model of friction and inertia can be calculated, for example, to model the system behavior of a spinning bike. The inertia is composed of the virtual mass of a flywheel and its shape, with friction terms representing a set braking force. Corresponding equations, for example, for energy and forces, can be established, which correspond to the system equations. and can be combined, where C1 and C2 are the friction coefficients for the braking force, J is the simulated inertia, n is the angular velocity, i.e. the speed of the simulated system, and M pedai the torque applied by the user to the pedals.

[0036] A virtual bicycle model can be created that is calculated to determine the physical control variables for an electric machine at any time. Internal friction, aerodynamic losses, rolling friction, potential energy, kinetic energy, inertia of a drive train, and freewheeling of a desired bicycle can be virtually simulated. For example, a system equation according to preferably with additional terms. Changes in the total energy can therefore preferably only be introduced by external forces.

[0037] A person skilled in the art will recognize that various models can be calculated, which have a simple, braked inertia, comparable to an ergometer or spinning bike, or even more complex models to represent different bicycles in real riding scenarios, such as an uphill ride, a downhill ride, a gear change, a change in surface, changes in wind conditions, in particular taking into account the weight of the rider and / or the weight of the bicycle.

[0038] A surface can be created, for example, by introducing vibrations into the drive train, for example through intentional torque ripple. This torque ripple can be created, for example, by feeding in an additional current with at least a higher frequency in addition to the current that generates the effective torque. Preferably, a controller adapts the vibration and / or torque ripple to the surface simulated for the current user, in order to give users the impression of a road, cobblestones, the edge of the road, a track, gravel, or even grass. Preferably, a controller supplies control signals for suitable vibration and / or torque ripple assigned to the individual sections of the route, depending on a calculated position in a virtual course.

[0039] In a particularly preferred embodiment, the motor control unit and / or the ergometer control unit are configured to detect a critical operating condition and control the bicycle ergometer based on the detected operating condition. In particular, a sudden change in force can be interpreted as a sign of unintentional pedaling force, and the electric motor can be controlled to dampen the pedaling force. Furthermore, a trapped leg or the like can be detected, in which case an emergency shutdown of the electric drive motor can occur, so that it no longer exerts any torque on the pedal crank.The advantageous detection of critical operating conditions allows the creation of a bicycle ergometer with increased safety, especially compared to spinning bikes, where a high inertia without a freewheel can lead to torque still being exerted on the trapped leg even when the leg is trapped, resulting in a significant risk of injury.

[0040] In a preferred embodiment of the method, the step of calculating a torque to be applied and / or a speed to be applied to the pedal crank comprises at least one of the following steps:

[0041] Determining a virtual system consisting of rider and bicycle, wherein the virtual system is preferably calculated based on a pre-calculated virtual inertia, a pre-calculated virtual external friction and / or a pre-calculated virtual internal friction;

[0042] Calculating a virtual energy of the virtual system based on a predetermined initial energy of the system, a virtual potential energy of the system and / or a virtual kinetic energy of the system; and

[0043] Calculating a virtual torque and / or a virtual speed based on the calculated virtual energy of the system, wherein the virtual torque and / or the virtual speed corresponds to the torque and / or the speed which the rider would have to transfer to a real system corresponding to the calculated virtual system in a real riding situation. The virtual torque and / or the virtual speed corresponds to a torque to be applied to the pedal crank and / or a speed to be applied to the pedal crank. Virtual torque and / or virtual speed or virtual system and the like is to be understood in particular as a simulation. The corresponding values ​​can be determined based on the selected training mode; a simulation of the corresponding virtual system is carried out, whereby it can be determined with which force orThe torque and / or speed the user would need to operate the virtual system's pedals. This corresponding force can then be specified by the electric motor on the bicycle ergometer.

[0044] The system could, for example, be a racing bike riding uphill. The bicycle ergometer control unit then calculates, based on stored physical models that are generally known in the state of the art, what drive force a rider would need to transfer to the bike to complete the uphill ride. This corresponding force can then be transferred to the pedal crank by appropriately controlling the electric motor.

[0045] In a particularly preferred embodiment of the method, the method comprises the steps of: comparing the detected torque and / or the detected speed at the pedal crank with the calculated torque to be applied and / or the calculated speed to be applied at the pedal crank; particularly preferably, the calculated torque to be applied is based on a pedaling speed, i.e. speed, so that the torque can be adjusted depending on the speed and offers the possibility of freewheeling; and

[0046] Setting the torque and / or speed to be applied to the pedal crank to a predetermined value, preferably to 0, if the detected torque and / or speed at the pedal crank is less than the sum of a predefined threshold value and the calculated torque and / or speed to be applied to the pedal crank. It is understood that the predefined threshold value can also be 0.

[0047] Through these two steps, a freewheel can be advantageously and technically easily implemented into the bicycle ergometer. In particular, this allows the bicycle ergometer to replicate the rolling state of a bicycle with a freewheel. A realistic training situation can be created that essentially corresponds to pedaling during a real bicycle ride.

[0048] It goes without saying that the presented bicycle ergometer also allows for the implementation of additional functions and / or gamification. In particular, the realistic simulation and the high degree of variability in the control allow for various game modes to be set up with the bicycle ergometer. One example would be linking various bicycle ergometers to a network, preferably the internet, with individual users traveling the same virtual route, forming a kind of race. It goes without saying that there are also options to slow down individual users for misbehavior or to reward users for exemplary behavior. In particular, it is conceivable to introduce a type of boost function in which the kinetic energy of the virtual simulated system is suddenly increased when an event occurs.

[0049] It goes without saying that other characteristics that make riding more pleasant or realistic can also be simulated. For example, torque ripple, which is avoided or reduced in current ergometers, can be simulated.

[0050] A system capable of controlling the speed and torque of an electrical machine in both positive and negative directions is called a 4-quadrant system. Operation in quadrants 1 and 3 is called "motor" operation, meaning that speed and torque have the same direction (both positive or both negative). This occurs when a drive drives a load and energy is consumed by the motor. Operation in quadrants 2 and 4 is called "generative," meaning that speed and torque have opposite directions (one negative and the other positive). This occurs when the motor brakes the load; the motor then generates electrical energy. This energy is either fed back into the grid, converted to thermal energy in a braking resistor, or stored in capacitors.

[0051] Coordinate transformations such as the Clarke and Park transformations are frequently used in the field-oriented control of three-phase AC machines. The Clarke transformation converts the time-domain components of a three-phase system (in the ABC coordinate system) into two components in an orthogonal stationary frame (β). In the Park transformation, the two components in the β-frame are converted into an orthogonal rotating reference frame (dq). Implementing these two transformations sequentially simplifies calculations by converting AC and voltage waveforms to DC signals. The invention can preferably operate without a mechanical freewheel, which would limit the wheel's operating mode to only one quadrant. In contrast, the electric machine can preferably support and / or generate speed and / or torque in both directions.

[0052] In this case, the invention can, for example, emulate a freewheeling behavior by generating a different torque at a negative direction of rotation and / or a speed below a predetermined threshold than above the predetermined threshold, for example the torque is less than or close to 0.

[0053] Alternatively, torque can be intentionally generated for negative speeds or negative torque can be generated for positive speeds, for example to enable eccentric muscle training and / or to simulate the behavior of a fixie bike.

[0054] In the following, embodiments of the invention are described with reference to the accompanying drawings. They show:

[0055] Figure 1 is a schematic side view of a bicycle ergometer according to the invention;

[0056] Figure 2 shows a schematic plan view of the bicycle ergometer according to Figure 1 with simplified control units;

[0057] Figure 3 shows, analogous to Figure 1, a side view of another bicycle ergometer according to the invention;

[0058] Figure 4 shows, analogously to Figure 2, a schematic plan view of the bicycle ergometer according to Figure 3; Figure 5 shows a schematic representation of a block diagram for controlling a bicycle ergometer according to the invention;

[0059] Figure 6 shows another variant of a block diagram for controlling a bicycle ergometer;

[0060] Figure 7 shows another variant of a block diagram for controlling a bicycle ergometer; and

[0061] Figure 8 schematically shows the steps of a method according to the invention for controlling a bicycle ergometer.

[0062] Figure 1 schematically shows a side view of a bicycle ergometer 10 according to the invention. The bicycle ergometer 10 has a stand 12 on which a saddle 14 and a handlebar (not shown in more detail) are arranged.

[0063] Control elements for the bicycle ergometer 10 can be integrated into the handlebar. It goes without saying that vital signs can also be recorded via contact with the handlebar.

[0064] The bicycle ergometer 10 further includes a crank 16 with pedals 18. The crank 16 is connected to an electric motor 22 by means of a traction mechanism comprising a belt 20. Consequently, when pedaling, power is transmitted from the crank 16 to the electric motor 22 by means of the traction mechanism. Furthermore, the electric motor 22 can exert power on the crank 16. It is understood that torque and force are used synonymously within the scope of this application, since applying pedal force results in a torque at the crank 16.

[0065] The bicycle ergometer 10 according to the invention therefore has no additional flywheel mass. Furthermore, the pedal crank 16 is directly connected to the electric motor 22. "Direct" means, in particular, that every rotation of the pedal crank 16 results in a rotation of the electric motor 22.

[0066] Figure 2 shows a schematic plan view of the bicycle ergometer 10 according to Figure 1, with the units for controlling the bicycle ergometer 10 also shown enlarged. The same reference numerals refer to the same features and will not be explained again.

[0067] The bicycle ergometer 10 has a power supply 24, which can supply power to the electric motor 22 via a motor control unit 26, so that the electric motor 22 can ultimately apply a torque and / or a rotational speed to the pedal crank 16. The motor control unit 26 is controlled by a bicycle ergometer control unit 28 with motor control signals.

[0068] A person skilled in the art will recognize that the motor control unit 26 and the bicycle ergometer control unit 28 do not necessarily have to be two different units, but can be integrated into one unit.

[0069] Figure 3 shows an alternative embodiment of a bicycle ergometer 10. In contrast to the variant shown in Figure 1, the pedal crank 16 is directly connected to the electric machine 22 by means of a gear, in particular a planetary gear 30. In this case, the electric machine 22 can be a so-called internal rotor, in which the stator is arranged radially outside and surrounds the rotor, wherein the rotor is connected in a rotationally fixed manner to a gear part of the planetary gear 30. The pedal crank 16 can be arranged within the planetary gear 30, in particular a sun gear of the planetary gear 30. This makes it possible to reduce the installation space required for the bicycle ergometer 10. A compact bicycle ergometer 10 can be created.It is understood that such a compact bicycle ergometer 10 can also be provided in a foldable or collapsible version in order to be able to store the bicycle ergometer 10 in a space-saving manner when not in use.

[0070] In Figure 4, in a manner analogous to Figure 2, the bicycle ergometer 10 according to Figure 3 is shown in plan view, wherein the energy supply 24, the motor control unit 26 and the bicycle ergometer control unit 28 are connected in an analogous manner to the electrical machine 22.

[0071] Figure 5 shows a schematic block diagram of a motor control unit 26 and a bicycle ergometer control unit 28.

[0072] The motor control unit 26 has two interfaces, one of which is connected to an inverse parking unit 34 via two PID controllers 32. A free interface is also connected to the inverse parking unit 34 via a PID controller 32, wherein the inverse parking unit 34 is connected to a pulse wave or pulse width modulation unit 36, which is connected to the electric machine 22 via a motor unit 38. The electric machine 22 is in turn connected to an encoder observer unit 40, which is connected to the non-free interface and to an input of the bicycle ergometer control unit 28. Furthermore, the encoder observer unit 40 is connected to both the inverse parking unit 34 and a parking unit 44.

[0073] A person skilled in the art will recognize that the field-oriented control of the machine described here can optionally be replaced by another control, such as direct torque control, direct torque control and / or direct self-control.

[0074] The motor unit 38 is also connected to a Clarke unit 42, which in turn is connected to the parking unit 44. The parking unit 44 is connected, on the one hand, to the free interface of the motor control unit 26 and, on the other hand, to the non-free interface of the motor control unit 26 after the first PID controller 32.

[0075] The bicycle ergometer control unit 28 has a calculation unit 46 for calculating internal friction, a calculation unit 48 for calculating external friction, and a torque calculation unit 50, all of which are connected to an inertia calculation unit 52. The inertia calculation unit 52 is in turn connected to the non-free input of the motor control unit 26 via an integrating unit 54. Furthermore, the parking unit 44 of the motor control unit 26 is connected to the torque calculation unit 50. Furthermore, the calculation units 46, 48 for calculating external friction and internal friction are connected to an output of the encoder observer unit 40.

[0076] The torque calculation unit 50 calculates the torque from a first current i q and a second current i d , preferably according to the formula where L d represents the inductance of a D-axis, L Qrepresents the inductance of a Q-axis, N describes the number of pole pairs of the electrical machine 22 and ip m a magnetic flux linkage. In other words, the torque calculation unit 50 calculates a torque of the electric machine 22 from parameters of the electric machine 22 and signals that can be detected by the electric machine 22.

[0077] The calculation unit 48 for calculating the external friction calculates a torque from a speed of the electric machine 22, preferably according to the formula

[0078] M = a> ■ CI where > is the speed and CI is a simulated virtual parameter.

[0079] The calculation unit 46 for calculating the internal friction also calculates a torque from a speed to and a second parameter C2, preferably according to the formula

[0080] OJ M = — ■ C2 M

[0081] The inertia calculation unit 52 calculates an angular acceleration a from the torque, in particular the summed torque of the calculation units 46, 48, 50, preferably according to the formula where J is a parameter that describes the moment of inertia of a rotating mass to be simulated.

[0082] CI is preferably a parameter of external friction, in particular Coulomb friction, C2 is a parameter of internal friction, preferably viscous friction, and J is an inertia parameter. Different driving modes can be realized by dynamically adjusting these parameters.

[0083] The external friction parameter CI is preferably used to describe aerodynamic losses.

[0084] It is understood that the previously described method for inertia simulation, which is based on the inertia J and the parameters C1 and C2, which can in particular be friction coefficients, preferably performs a rotational calculation or simulation. In simplified terms, a system is simulated by the bicycle ergometer control unit 28, with corresponding control signals being transmitted to the motor control unit 26, which cause the electric machine 22 to be subjected to a torque or speed that would be required by a rider during a real ride with the simulated system.

[0085] It goes without saying that the torque or speed to be applied can also be negative or 0.

[0086] A total energy E Gesamt results in c can be an initial energy content of the system, for example if the simulated flywheel mass should already have a certain speed at the start of training.

[0087] Figure 6 shows a preferred embodiment of a motor control unit 26 and a bicycle ergometer control unit 28. In contrast to the embodiment shown in Figure 5, a freewheel is implemented, which can preferably be activated via a switch. This freewheel has a sign unit 56 connected to an output of the encoder observer unit 40 and connected to the non-free input downstream of the first PID controller 32 and upstream of the second PID controller 32, downstream of the parking unit 44.

[0088] This represents a technically simple variant for setting up a freewheel, in which a direction-dependent or threshold-dependent component is introduced. Direction-dependent means that the pedal speed, and thus also the drive speed, is positive or negative relative to a pre-calculated speed.

[0089] A threshold-dependent component means that a drive speed is above or below a predefined threshold.

[0090] Consequently, two rotational signals are used, a virtual rotational speed a>, which is precalculated by the bicycle ergometer control unit 28, and a real drive speed n r = a) r / (2n), which can be measured, for example, at the electric machine 22. The torque calculated from the equations described above is generated at the electric machine 22 in the embodiment according to Figure 6 only when the rotational speed is positive.

[0091] Alternatively, the torque is only generated when the speed is above a predetermined threshold. This can be achieved, for example, using a multiplexer or multiplier that determines the sign of the difference between the speed and the threshold via the sign unit 56. In this case, the torque is only generated when the speed condition is met. Such a freewheeling behavior is implemented in the embodiment according to Figure 6 by changing the output of the first PI or PID controller 32 via this speed condition, should the PI or PID controller 32 have implemented an anti-windup function, or should the integrator unit 54 stop precisely when the speed condition is not met.

[0092] It goes without saying that the equations described above continue to be calculated even in the case of freewheeling. In other words, the system continues to be simulated.

[0093] It is further understood that the threshold can be changed dynamically, for example as a fraction of the particularly preferably low-pass filtered measured speed of the past, as long as this speed condition has been met.

[0094] A professional will recognize that a freewheel can also be set up in other ways.

[0095] In an extended version, for example, two systems can be simulated.

[0096] The block diagram according to Figure 5 represents the bicycle up to the hub before the freewheel. A second system could be created that includes a different inertia that virtually describes the pedal and possibly the chain, and at least one friction term, preferably several friction terms, including gear friction, chain friction, but preferably no aerodynamic friction.

[0097] The two systems can be coupled, for example, via a torque, whereby a torque is only transferred from the second to the first system if the torque of the second system is positive and if the speed of the second system has reached at least a factor r of the first system.

[0098] Figure 7 shows a further variant of a bicycle ergometer control unit 28 according to the invention. The motor control unit 26 is constructed as described in the embodiments according to Figures 5 and 6 and will not be explained in more detail.

[0099] The bicycle ergometer control unit 28 has a wheel diameter calculation unit 58, which can be used to calculate a predetermined wheel diameter, which can be varied depending on the bicycle type, and a gear ratio calculation unit 60, both of which are connected to a force calculation unit 62. The force calculation unit 62 is also connected to the parking unit 44, in particular to both outputs of the parking unit 44 of the motor control unit 26.

[0100] Furthermore, the force calculation unit 62 is connected to a bicycle dynamics model calculation unit 80 and, in particular, transmits a calculated force to the bicycle dynamics model calculation unit 80. The wheel diameter calculation unit 58 and the gear ratio calculation unit 60 are further connected to a speed calculation unit 74, wherein the speed calculation unit 74 is further connected to a freewheel calculation unit 76.

[0101] In addition, the speed calculation unit 74 is connected to the bicycle dynamics model calculation unit 80, wherein the bicycle dynamics model calculation unit 80 is fed back via the integrating unit 54.

[0102] The bicycle ergometer control unit 28 also includes a ground condition calculation unit 64, a rider weight calculation unit 66, a wheel weight calculation unit 68, an air density calculation unit 70, and a gradient calculation unit 72, which transmit data to the bicycle dynamics model calculation unit 80. The freewheel calculation unit 76 is connected to the input of the motor control unit 26 and also to an output of the encoder observer unit 40.

[0103] The bicycle dynamics model calculated in this way satisfies, for example, the formula where a represents the resulting acceleration, and the total mass is given as the weight of the rider plus the weight of the bicycle. The individual components can be described as follows:

[0104] For example, air resistance can be calculated using the formula be described, where c w is the drag coefficient, p is the air density, A is the frontal area of ​​the system, and v is the speed of the system. The system is understood here to be the simulated rider and bicycle.

[0105] The rolling friction can be calculated, for example, using the formula be described, where p B oden the rolling friction coefficient, c Boden a multiplier for soil conditions and gradient is the gradient in %.

[0106] The force for gaining height, the so-called slope lift force, can be calculated using the formula

[0107] F gradient = mass ges ■ 9.81 be described, where mass ges is the mass of the system, and gradient is the gradient in %. It is understood that other calculation methods may also be used. In this case, a gradient of 100% corresponds to a gradient of 45° in a linear relationship.

[0108] The total energy is where the first term represents the kinetic energy stored in the system and the second term represents the potential energy stored in the system. The third term, the constant c, can represent an initial velocity or the start on a hill.

[0109] The combination of these forces is determined by the force F netThis corresponds to the force the rider applies by pedaling to accelerate the system. This force can be calculated based on the torque applied by the electric motor, the gear ratio, and the wheel diameter, as described above.

[0110] A freewheel logic condition can, for example, be as follows: if w_soll>w_ist, then w_soll is set to w_soll, otherwise no torque is generated with the electric machine 22, where w_soll is a calculated target speed of the electric machine 22 and w_ist is a current speed of the electric machine 22.

[0111] Alternatively, the logic condition can be: if a) so u > a) ist is, then i q = 0 regardless of the speed controller. The speed controller is set accordingly at a) ist > a) so u reactivated.

[0112] A person skilled in the art will recognize that the ergometer control unit 28 may also include an alternative control logic to that shown above by way of example.

[0113] Figure 8 schematically describes the steps of a method according to the invention, in particular a method for controlling a bicycle ergometer 10 as defined above.

[0114] In a first step S10, a torque and / or a speed on the pedal crank is detected.

[0115] In a second step S20, a torque and / or rotational speed to be applied to the pedal crank is calculated based on a predetermined training mode. The calculation can be performed as described with reference to Figures 5 to 7.

[0116] In an optional third step S30, the detected torque and / or the detected speed at the pedal crank is compared with the calculated torque to be applied and / or the calculated speed to be applied at the pedal crank.

[0117] In a further optional fourth step S40, the torque to be applied and / or the rotational speed to be applied to the pedal crank is set to a predetermined value if the detected torque and / or the detected rotational speed at the pedal crank is less than the sum of a predefined threshold value and the calculated torque and / or the rotational speed to be applied to the pedal crank. It is understood that the predefined threshold value can also be less than 0 or 0.

[0118] In a further fifth step S50, the electric machine is controlled to apply the torque and / or speed to the pedal crank to be applied.

[0119] The second step S20 may in particular comprise one or more of the following steps:

[0120] Determining a virtual system consisting of rider and bicycle, wherein the virtual system is preferably determined based on a pre-calculated virtual inertia, a pre-calculated virtual external friction and / or a pre-calculated virtual internal friction.

[0121] Calculating a virtual energy of the virtual system based on a predetermined initial energy of the system, a virtual potential energy of the system and / or a virtual kinetic energy of the system.

[0122] Calculating a virtual torque and / or a virtual speed based on the calculated virtual energies of the system, wherein the virtual torque and / or the virtual speed corresponds to a detected torque to be applied to the pedal crank and / or a detected speed to be applied to the pedal crank.

[0123] An expert recognizes that, to manage perceived instabilities, mechanical damping could be integrated into the drivetrain as a temporary solution. This damping is preferably kept as small as possible and can include both braking and inertia components.

[0124] A person skilled in the art will recognize that control instability due to freewheeling can be counteracted by reducing the gear ratio and speed of the load machine to increase dynamics. An alternative state control concept can be applied here, and a fast feedforward control can be developed with additional position sensors and, if necessary, force sensors on the pedals.

[0125] It goes without saying that, for high pedaling forces, a control concept can be developed that, if possible, avoids load stall under any circumstances. Alternatively, such load cases can be anticipated in advance, warning the user with a warning signal (e.g., sound, light, and / or vibration). However, since this usually involves short-term explosive force recruitment, a trainable statistical extreme value model can be used to estimate the onset of such a case at an early stage.

[0126] The ergometer control unit can be configured to execute at least one of the methods according to one of claims 7 to 9. The computer program product can be configured, in particular, in the form of an app on a handheld device, such as a tablet or a smartphone, and at least partially assume or supplement the functionality of the ergometer control unit.

[0127] The invention has been comprehensively described and explained with reference to the drawings and the description. The description and explanation are to be understood as exemplary and not restrictive. The invention is not limited to the disclosed embodiments. Other embodiments or variations will become apparent to those skilled in the art upon use of the present invention and upon careful analysis of the drawings, the disclosure, and the following claims.

[0128] In the claims, the words "comprising" and "having" do not exclude the presence of further elements or steps. The undefined article "a" or "an" does not exclude the presence of a plurality. A single element or unit can perform the functions of several of the units recited in the claims. The mere mention of some measures in several different dependent claims should not be understood to mean that a combination of these measures cannot also be used advantageously. Reference signs in the claims are not to be understood as limiting. A computer program can be stored / distributed on a non-volatile data carrier, for example on an optical memory or on a solid-state drive (SSD).A computer program may be distributed together with hardware and / or as part of hardware, for example via the Internet or via wired or wireless communication systems.

Claims

Patent claims 1. A bicycle ergometer (10), comprising: a pedal crank (16) with pedals (18); an electric machine (22) drivingly connected to the pedal crank (16); a power supply (24) for operating the bicycle ergometer (10); a motor control unit (26) for controlling the electric machine (22) based on motor control signals; an ergometer control unit (28) for generating the motor control signals; wherein the bicycle ergometer (10) is designed to be flywheel-free; and the motor control unit (26) is designed to control the electric machine (22) based on the motor control signals in order to generate a predefined torque and / or a predefined speed at the pedal crank (16).

2. Bicycle ergometer (10) according to the preceding claim, wherein the pedal crank (16) is connected to the electric machine (22) in a driving manner by means of a traction mechanism, preferably a belt (20).

3. Bicycle ergometer (10) according to claim 1, wherein the pedal crank (16) is drivingly connected to the electric machine (22) by means of a spur gear and / or a planetary gear (30).

4. Bicycle ergometer (10) according to one of the preceding claims, wherein the motor control unit (26) is designed to actively and preferably dynamically control the electric machine (22) in two quadrants, preferably in four quadrants.

5. Bicycle ergometer (10) according to one of the preceding claims, wherein the ergometer control unit (28) is configured to set up at least one of the following training modes: inertia with freewheel; inertia without freewheel; bicycle physics model with elevation-Z-distance profile without freewheel; bicycle physics model with elevation-Z-distance profile with freewheel; an eccentric load situation to maximize muscle training effects and / or a classic ergometer.

6. Bicycle ergometer (10) according to one of the preceding claims, wherein the motor control unit (26) and / or the ergometer control unit (28) is designed to determine a critical operating state and to control the bicycle ergometer (10) based on the determined critical state.

7. Method for controlling a bicycle ergometer (10), in particular a bicycle ergometer (10) according to one of the preceding claims, comprising the steps: Detecting (S10) a torque and / or a rotational speed at the pedal crank (16); Calculating (S20) a torque to be applied and / or a speed to be applied to the pedal crank (16) based on a predetermined training mode; and Controlling (S50) the electric machine (22) to apply the torque and / or speed to the pedal crank (16) to be applied.

8. Method according to one of the preceding claims, wherein the step of calculating (S20) a torque to be applied and / or a speed to be applied to the pedal crank (16) comprises at least one of the following steps: Determining a virtual system consisting of rider and bicycle, Calculating a virtual energy of the virtual system based on a predetermined initial energy of the system, a virtual potential energy of the system and / or a virtual kinetic energy of the system; and / or Calculating a virtual torque and / or a virtual speed based on the calculated virtual energy of the system; wherein the virtual torque and / or the virtual speed corresponds to a torque to be applied to the pedal crank (16) and / or a speed to be applied to the pedal crank (16).

9. Method according to one of the preceding claims, comprising the steps: Comparing (S30) the detected torque and / or the detected speed at the pedal crank (16) with the calculated torque to be applied Torque and / or the calculated speed to be applied at the crank (16); and Setting (S40) the torque to be applied and / or the rotational speed to be applied to the pedal crank (16) to a predetermined value if the detected torque and / or the detected rotational speed at the pedal crank (16) is less than the sum of a predefined threshold value and the calculated torque to be applied to the pedal crank (16) and / or the calculated rotational speed to be applied to the pedal crank (16).

10. Computer program product with program code for carrying out the Steps of the method according to the preceding claim when the program code is executed on a computer.

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