Method for controlling a drive motor of a bicycle
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- ZF FRIEDRICHSHAFEN AG
- Filing Date
- 2024-06-20
- Publication Date
- 2026-04-29
AI Technical Summary
Conventional cycling methods often fail to provide targeted training effects due to inappropriate physical stress, which can be ineffective or harmful, and are influenced by route profiles, reducing motivation for effective training.
A method for controlling a bicycle's drive motor that determines a load setpoint based on the rider's vital signs and current load, adjusting the motor's support to maintain a desired load, regardless of the route profile, by activating or counteracting propulsion forces to ensure optimal training conditions.
This method allows for consistent and effective training by maintaining a desired load on the rider, independent of the route profile, ensuring optimal training effects and improved fitness outcomes.
Smart Images
Figure EP2024067218_26122024_PF_FP_ABST
Abstract
Description
[0001] Method for controlling a drive motor of a bicycle
[0002] Technical area
[0003] The present invention relates to a method for controlling a drive motor of a bicycle, particularly for training purposes. Furthermore, the present invention also relates to an associated control device and an associated bicycle.
[0004] State of the art
[0005] Cycling continues to enjoy increasing popularity. It is practiced not least to maintain or improve one's fitness. Sports medicine has shown that targeted training approaches with individually adapted load levels can have very positive effects on training, such as cardio training, fat burning, or increased muscular performance. Inappropriate physical exertion, on the other hand, can be ineffective or even detrimental to health development goals.
[0006] Depending on the route profile, cycling without electric motor support may require the rider to exert a level of effort that may not be conducive to a targeted training effect or may reduce the motivation for targeted training.
[0007] Description of the invention
[0008] It is therefore an object of the present invention to reduce the above-mentioned disadvantages of conventional cycling and to provide a more suitable method, a control device and a bicycle therefor.
[0009] According to a first aspect, the present invention relates to a method for controlling a drive motor of a bicycle. The bicycle can be, for example, a pedelec or an e-bike. The drive motor is, for example, an electric motor. First, in this method, a target load value for a rider of the bicycle is determined. Such a target load value can, as will be described in more detail below, be, for example, a target value for a power output, also called target power, which the rider should produce, for example, for optimal training. Such a determination can, for example, be reading out a corresponding value from a memory.However, it can also be determined by deriving the target load value, such as a target power, from a training plan, such as a desired load profile over time. It can also be determined based on the rider's vital signs, so that the rider's desired load is ultimately derived based on the rider's current vital signs, such as their current heart rate.
[0010] The current load on the user for propelling the bicycle is then determined. This can, for example, involve determining the power currently applied by the user for propulsion, such as the power applied by the user to a pedal of the bicycle. This can, for example, be derived based on the current cadence and the current torque on the pedal crank. However, the current load can also be other values, such as a currently applied torque or a current cadence of the rider or user for propelling the bicycle. A current load can therefore be a value for those parameters that the user applies to propel the bicycle, for example via a force applied to the pedals.
[0011] Then, in a further step, the drive motor can be controlled based on the load setpoint in such a way that the current load corresponds to the load setpoint.
[0012] Accordingly, based on an evaluation of the current load and the target load value, the motor can be controlled and used in such a way that only the load on the driver is caused that corresponds to the target load value and thus the desired load for the driver. In one example, this could mean that the target power to be applied by the user is first determined, then it is determined in a second step that a higher power is currently being applied, and thus the required differential power to reduce the user's load to the target value is applied by the drive motor and thus compensated.
[0013] In clear contrast to known control methods, the system is controlled in such a way that the desired load on the driver is always present.
[0014] This means that the support power of the drive motor can be used in such a way that the load on the rider or user can be ideally adapted for an intended training effect, regardless of the route profile.
[0015] In one aspect, the control of the drive motor can comprise at least one of the following controls, but also any combination thereof.
[0016] On the one hand, the drive motor can be controlled to apply or increase a force that supports propulsion if the user's current load is greater than the target load. This condition, briefly discussed above, occurs when the power currently applied by the user or the user's current load is greater than the desired load, for example, for the training effect. Assistance can then be provided in such a way that the necessary difference is provided by the drive motor.
[0017] However, a control system also provides for the drive motor to be used to apply a force counteracting propulsion. This is the case if the user's current load is less than the target load and the drive motor is not currently applying any force to assist propulsion. This can be the case, for example, if the rider is assisted in progress by a tailwind, when riding downhill or on flat terrain, when a high target load is desired. Accordingly, the electric motor is used to brake the bike and thus increase the load required for progress. Accordingly, it is also possible, for example, to achieve a consistently high load value when riding downhill or on flat terrain, or even with a tailwind.In a third option, control is also provided such that the drive motor is activated to reduce the propulsion-assisting force if the user's current load is less than the target load value and the drive motor is currently applying a propulsion-assisting force. This means that if the current load is too low, but the motor is currently applying a force to assist the user, this assistance is reduced in order to reach the desired target load value again.
[0018] With the above-mentioned controls, it is therefore possible to achieve an optimal load on the user, completely and independently of the route profile and also independently of, for example, an assisted tailwind, similar to what is possible with indoor bicycles, for example.
[0019] According to one embodiment, if the drive motor applies a force that counteracts propulsion, the motor can be operated in generator mode. This means that the power then applied by the user is converted into electrical power by the generator and can then be fed to and stored in a battery of the bicycle.
[0020] In order to be able to apply a force that counteracts propulsion, a system that provides a freewheel in the power flow of the drive system can also be provided with a switching device for bridging to enable a negative torque with the electric motor and thus a force that counteracts propulsion. In this case, the above-mentioned method can then provide for switching a switching device to bridge a freewheel if a force that counteracts propulsion is to be applied.
[0021] In one embodiment, the target load value is determined based on a load profile, as briefly mentioned above. Thus, the target load value is to be understood as the current target load value, and the load profile specifies a desired load for the rider over time. Accordingly, a curve for a desired load for the user over time can be specified as a load profile, and at any time, a desired current target load value can be derived from this, which can then be fed into the above-mentioned method in the determination step. Thus, even fluctuations independent of the route profile, such as high-intensity training sessions with several short load bouts and short regeneration phases, can be mapped independently of the route profile.
[0022] In one embodiment, it may also be provided to determine the target load value based on at least one of the rider's vital signs. A vital sign can be, for example, a heart rate, a heart rate range, body temperature, oxygen saturation, an insulin level, an energy output, or heart rate variability. Based on this vital sign, the optimal target load value for the user can then be derived.On the one hand, this can result from the user's current fitness, such as heart rate variability, but a certain heart rate range or similar can also be defined, and the target load value can then be controlled in such a way that, by regulating the target load value, the user's current heart rate or another current vital sign of the user is kept within a certain predetermined range, such as within a certain heart rate range. Accordingly, the target load value can be determined in such a way that when the driver applies the load defined by the target load value, at least one vital sign corresponds to a target vital sign. However, in one embodiment, merely a general vital sign describing the driver's fitness can be used to determine an optimal target load value.
[0023] In one embodiment, it is also conceivable to define a certain vital sign profile that specifies the desired course of a vital sign over time, to derive the current target load value from this, and to feed this into the method defined above in the determining step. Thus, for example, a target load value can be regulated in such a way that a vital sign, such as the user's heart rate, approximates a desired curve over time. Thus, for example, training courses can be mapped with zones with a high heart rate and training zones with a lower heart rate.
[0024] For this purpose, in one embodiment, a vital sign can be recorded using a measuring device. This can be, for example, a heart rate monitor or similar. In one embodiment, the target load value can be a target cadence. Thus, a certain cadence is specified for the user, whereby in this case, the current load specified in the method is the current cadence. This allows training at a specific predefined cadence regardless of the route profile.
[0025] In one embodiment, however, the target load value can also be a target torque. In this case, the current load is the current torque. This allows the rider to always train with a certain torque that they must apply to the bicycle's pedals.
[0026] In one embodiment, briefly discussed above, the target load value can also be a target power. This allows the user or rider to specify the power they need to apply to the pedals. The current load is then the current power the rider is applying for propulsion. Such power can be determined, for example, from torque and cadence.
[0027] A combination of the above-mentioned specifications is also possible, so that, for example, a certain power output but also a certain cadence is specified. In one embodiment, it can be provided to further control the bicycle's gearshift depending on the target load value. Thus, if, for example, the cadence is too low, but the target power output is correct, a different gear can be selected to allow the rider to pedal at a higher cadence while maintaining the same power output.
[0028] In one embodiment, the target load value can also be determined from at least one of a rider input or a stored rider profile. This can, for example, provide for the storage of the aforementioned vital signs in a rider profile or also the storage of the desired load profile in a rider profile. Furthermore, the rider input can allow the rider to adjust the target values selected by the system, for example by adjusting the aforementioned load profile. The rider profile can be stored, for example, in a control device of the bicycle itself, but also in a device wirelessly connected to the bicycle, such as a smartphone, or in an external storage device, such as a cloud server. Synchronization of the data mentioned here between the units mentioned here is also possible.
[0029] The present invention further relates to a control device for implementing the method according to one of the preceding claims. This can be, for example, a control device of the bicycle, such as a drive motor control device. Distribution of the above-mentioned functionalities across multiple units, such as distribution between a wirelessly or wired connected terminal and a control device of the bicycle, is also possible.
[0030] The invention further relates to a bicycle with the aforementioned control device for implementing the methods discussed above. This bicycle further comprises at least the drive motor discussed above and the battery discussed above for supplying the drive motor with electrical energy.
[0031] In one embodiment, the present invention further comprises a computer program product for carrying out the steps of the methods discussed above. The computer program product can, for example, be executed on the control device.
[0032] Short description of the characters
[0033] Figure 1 shows a bicycle with an example route.
[0034] Figure 2 shows a flow chart of a process.
[0035] Detailed description of embodiments
[0036] Figure 1 shows a bicycle 100 traveling on a route profile consisting of sections 104, 105, and 106. The cyclist is not shown.
[0037] The bicycle 100 has a drive motor 101, which in this example is designed as a mid-mounted motor in the area of the bottom bracket. This motor is electrically connected to a battery 102, which supplies the drive motor 101 with electrical energy. Furthermore, the bicycle has a control device 103, which executes the method described below and controls the drive motor 101 accordingly.
[0038] In the method shown in Figure 2, the target load value for a rider of bicycle 100 is first determined in step 1. In the example shown here, this is done by recording a vital sign of the rider, in this case the heart rate, and comparing it with a target heart rate. The target load value is then determined from this. For example, if the user's heart rate is above a target heart rate value, the rider's target load value is reduced accordingly. Then, in step S2, a current load on the rider to propel the bicycle 100 is determined. In the present example, this can be done by determining the torque and the speed at the pedal crank of the bicycle 100. Then, in step S3, the drive motor 101 is controlled based on the target load value such that the current load corresponds to the target load value.
[0039] If the bicycle 100 moves, for example, in the slightly rising section 104 in Figure 1, the drive motor 101 will be controlled in such a way that the drive motor 101 applies a force that supports propulsion if the current load of the rider is above the load target value.
[0040] In section 105, however, the rider's current load will tend to be below the target value, as the steep gradient requires little rider power to move forward. Accordingly, in this section, drive motor 101 is activated to apply a force that counteracts propulsion. Thus, bicycle 100 is actively braked to achieve the desired rider load and thus bring the current load closer to the target load.
[0041] In the flat section 106, the control will then be such that no counteracting force is applied by the drive motor 101, since the load can likely be achieved solely by the force required for progress on the flat. Thus, regardless of the route profile, an ideal load and thus an ideal training effect for the cyclist can be achieved.
[0042] Reference symbol
[0043] 100 bicycles
[0044] 101 Drive motor
[0045] 102 Battery
[0046] 103 Control device
[0047] 104 slightly uphill section
[0048] 105 steeply descending section
[0049] 106 straight section
[0050] S1 Determining a load setpoint
[0051] S2 Determining a current load
[0052] S3 Control of the drive motor
Claims
Patent claims 1. A method for controlling a drive motor (101) of a bicycle (100), comprising the steps of: - determining (S1) a target load value for a rider of the bicycle (100); - determining (S2) a current load on the rider to propel the bicycle (100); - Controlling (S3) the drive motor (101) based on the load setpoint such that the current load corresponds to the load setpoint.
2. The method according to claim 1, wherein the control (S1) of the drive motor (101) comprises at least one of: - controlling the drive motor (101) to apply a force that supports propulsion if the current load on the driver is greater than the load target value, - controlling the drive motor (101) to apply a force counteracting the propulsion if the current load on the driver is less than the load target value and the drive motor does not apply a force supporting the propulsion, - Controlling the drive motor (101) to reduce a propulsion-supporting force if the current load on the driver is less than the target load value and the drive motor applies a propulsion-supporting force.
3. Method according to claim 2, wherein in the case of the application of a force counteracting the propulsion, the drive motor (101) is operated in a generator mode and the generated electrical energy is supplied to a battery (102) of the bicycle (100).
4. Method according to one of the preceding claims, wherein the load target value is a current load target value, and this is determined based on a load profile, wherein the load profile defines a desired load of the driver over a time.
5. Method according to one of the preceding claims, wherein the target load value is determined based on at least one vital value of the driver, wherein the load target value is determined in such a way that when the driver applies the load defined by the load target value, at least one vital value corresponds to a vital target value.
6. The method according to claim 5, wherein the at least one vital sign is recorded using a measuring device.
7. A method according to any one of the preceding claims, wherein the load setpoint is one of: - a target cadence, where the current load is the current cadence; - a target torque, where the current load is the current torque; and - a target performance, where the current load is the current performance.
8. Method according to one of the preceding claims, wherein the load target value is determined from at least one of: - an input from the driver; - a saved driver profile.
9. Control device (103) for carrying out the method according to one of the preceding claims.
10. Bicycle (100) include: - a control device (103) according to claim 9; - a drive motor (101); - a battery (102) for supplying the drive motor (101) with electrical energy.