Control method for a bicycle, control device and bicycle with the control device

Abstract

A control method for a bicycle (1) having a drive device (2) for at least temporarily electrically driving a drive wheel (3) of the bicycle (1) to assist in pushing the bicycle (1) is proposed, comprising the following steps: detecting an actual slip value on the drive wheel (3) on the basis of a deviation between a target value and an actual value with regard to the rotational state of the drive wheel (3); regulating the electric machine (7) on the basis of the actual slip value in the direction of a permissible slip value that is lower than the actual slip value.

Description

[0001] The present invention relates to a control method for a bicycle. In particular, the present invention relates to a control method for a bicycle configured as a pedelec, with which any slippage present on a drive wheel of the bicycle can be reduced. Furthermore, the present invention relates to a control device configured to carry out the control method, as well as to a bicycle having such a control device.

[0002] The prior art according to DE 10 2021 118 362 B3 discloses a pedelec with an electric drive unit. This prior art includes a motor controller and a slip detection unit. This unit determines a slip value, which is used to intervene in the motor controller to reduce the slip.

[0003] In one aspect, the present invention relates to a control method for a bicycle having a drive device for at least temporarily electrically driving a drive wheel of the bicycle to assist in pushing the bicycle. The drive device can, for example, be designed to provide pushing assistance. For example, the user can activate a pushing assistance mode, in which case the control method is also activated. Alternatively, the control method can also be additionally activatable when the pushing assistance is activated. The drive device can additionally also serve to at least temporarily electrically assist a drive of the drive wheel of the bicycle that is effected by muscle power. The muscle power can be introduced into the drive device via a crank device and transmitted to an output element of the drive device via a transmission device.For example, in a normal riding mode, the drive system can assist the rider in propelling the bicycle by pedaling. The bicycle can be configured, for example, as a pedelec. The drive system has an electric motor for providing a drive torque for electrical assistance, wherein a torque from the electric motor can be applied to the output element of the drive system. The torque can be transmitted to the output element, for example, via the transmission device. The electric motor can also be configured for recuperation.

[0004] The control procedure has the following steps: - detecting an actual slip value at the drive wheel based on a deviation between a target value and an actual value with respect to a rotational state of the drive wheel; and - Controlling the electric machine based on the actual slip value toward a permissible slip value that is lower than the actual slip value, for example, controlling the drive torque and, alternatively or additionally, a drive speed of the electric machine, for example, using a closed control loop. Optionally, the control method also includes the following step: At least temporarily controlling the electric machine, for example its drive torque or its drive speed, upon detection of a predetermined difference between the actual slip value and the permissible slip value in order to reduce the difference between the actual slip value and the permissible slip value using a target value control.

[0005] The control method according to the above-mentioned aspect is applicable, for example, to a bicycle in which a pushing force of a person pushing the bicycle can be combined with a drive power output by the electric machine. In normal riding operation, for example, in the bicycle, muscle power introduced into the drive device by the crank device can be combined with a drive power output by the electric machine. The drive device can take on various configurations as long as the concept underlying the invention can be realized. The bicycle to which the control method according to the above aspect is applicable can have a front wheel and a rear wheel. The front wheel can be a non-driven wheel, while the rear wheel can be the drive wheel.The drive device can output a drive force via the output element, which can be transmitted to the drive wheel by suitable means. For example, the electric motor can be operatively connected to the drive wheel via a chain or belt. For example, the electric motor can also be designed as a hub motor. In a predetermined operating state, the bicycle can be operated exclusively by muscle power, for example when pushing or, alternatively or additionally, when riding. Furthermore, the drive device can be operated such that the drive force provided by the electric motor is based on predetermined parameters.The predetermined parameters may include a rotational speed of the crank mechanism, a speed of the bicycle relative to a surface, a target push assist force, a target push speed, and a rotational speed of at least one of the front wheel and the rear wheel. Further parameters may be taken into account for controlling the electric motor.

[0006] The drive device can be controlled in a predetermined operating state such that the electric machine is controlled with regard to a rotational speed. The rotational speed of the electric machine can specify the rotational speed of the drive wheel, taking into account a predetermined transmission ratio in a drive force curve between the electric machine and the drive wheel. The transmission ratio in the drive force curve between the electric machine and the drive wheel can be variable. In this case, it is expedient to determine the transmission ratio and take it into account for the control method. The rotational speed of the electric machine and thus the rotational speed of the drive wheel can be limited to a maximum rotational speed in an operating state with electrical assistance from the electric machine.This measure allows the bicycle's speed to be limited to a maximum speed when operating with electrical assistance from the electric motor. This allows, for example, a predetermined maximum pushing speed to be specified with motor assistance. A predetermined speed control method can be provided for controlling or regulating the speed of the electric motor. The speed control method can be implemented separately from the control method described here.

[0007] In the present aspect, the actual slip value can refer to a value that reflects slippage of the drive wheel relative to the surface on which the bicycle is traveling. The actual slip value is based on the difference between a peripheral speed of the drive wheel and a speed of the bicycle relative to the surface.

[0008] According to the present aspect, the permissible slip value can be determined in advance based on empirical studies. The permissible slip value can be a fixed value. Alternatively, the permissible slip value can be variable and thus alterable depending on predetermined influencing factors. In particular, the permissible slip value can vary depending on the speed of the bicycle over the ground. The permissible slip value can be determined from the difference between the peripheral speed of the drive wheel and the speed of the bicycle over the ground and can represent a value that enables safe pushing. For example, a push assist on steep inclines and, alternatively or additionally, wet roots can otherwise lead to the drive wheel spinning. This can cause the drive wheel to slip sideways, causing the user and the bicycle to lose their balance.In addition, a user often leans on the bike while pushing, meaning a loss of traction can quickly lead to a fall. Furthermore, a loss of traction can unexpectedly result in the user having to support the entire weight of the bike, for example, which can be uncomfortable.

[0009] Alternatively, the actual slip value can be a temporal change in the difference between the peripheral speed of the drive wheel and the speed of the bicycle over the ground. Likewise, the permissible slip value can be a permissible temporal change in the peripheral speed of the drive wheel and the speed of the bicycle over the ground.

[0010] The actual slip value can be determined by comparing the speed of the bicycle over the ground and the peripheral speed of the drive wheel, or their changes over time. The speed of the bicycle can be determined using a speed sensor. Furthermore, the speed of the bicycle over the ground can be determined by measuring the rotational speed and thus the peripheral speed of a non-driven wheel, in particular the front wheel of the bicycle.

[0011] According to the present aspect, a closed control loop can be used to control the drive torque of the electric machine based on the actual slip value. Thus, the actual slip value is continuously compared with the permissible slip value, and the drive torque of the electric machine is changed accordingly to reduce the difference between the actual slip value and the permissible slip value. If the peripheral speed of the drive wheel is greater than the speed of the bicycle over the ground, the drive torque of the electric machine is reduced by the closed control loop according to a predetermined profile. The predetermined profile can be a time profile. In this way, a propulsive force acting between the drive wheel and the ground is reduced, so that the actual slip value is reduced.This also allows for an anti-slip function when using the push assist function. This prevents or at least limits rear wheel spin. As soon as excessive wheel slip is detected, the torque of the electric motor or its speed can be reduced to restore the drive wheel to a state with sufficient traction, relieving the rider's strain when pushing the bike.

[0012] According to the present aspect, the drive torque of the electric machine can be controlled, at least temporarily, upon detection of a predetermined difference between the actual slip value and the permissible slip value in order to reduce the difference between the actual slip value and the permissible slip value. Target value control is used in which the drive torque is set based on a predetermined specification. This specification can include an immediate reduction in the drive torque and, alternatively or additionally, a reduction in the speed of the electric machine upon detection of the predetermined difference between the actual slip value and the permissible slip value, so that the actual slip value approaches the permissible slip value.Furthermore, the predetermined specification can comprise a predetermined temporal progression based on the drive torque of the electric machine that exists upon detection of the predetermined difference between the actual slip value and the permissible slip value. The predetermined temporal progression can be configured as a ramp function. Furthermore, the predetermined temporal progression can represent a progressive or degressive function over time. In this control, it can be provided that the drive torque of the electric machine is reduced to zero based on the detection of a predetermined difference between the actual slip value and the permissible slip value if the actual slip value does not reach the permissible slip value after a predetermined time.

[0013] The permissible slip value can be variable. The permissible slip value can also be set to zero or close to zero. As a practical alternative, the permissible slip value can be set to a value that allows the bicycle to be safely pushed, whereby this permissible slip value can be determined empirically.

[0014] In the aforementioned target value control, a reduction in the peripheral speed of the drive wheel is achieved by correspondingly controlling the drive torque of the electric machine. According to the above aspect, the inertia of moving masses, including rotating masses, can be taken into account in the target value control. These masses are naturally subject to a certain mass inertia. The mass inertia of the drive wheel can be taken into account in the target value control in order to achieve a predetermined peripheral speed of the drive wheel over time by adjusting the drive torque of the electric machine. Similarly, the mass inertia of other moving elements, such as a drive chain and rotating elements of the drive device, can be taken into account for the target value control.

[0015] According to the aforementioned aspect, the control of the drive torque or the drive speed of the electric machine using the closed control loop and the at least temporary control of the drive torque of the electric machine using the target value control can be carried out simultaneously. In this case, the adjustment of the drive torque of the electric machine by the control using the closed control loop can be superimposed by the adjustment of the drive torque of the electric machine using the target value control. Furthermore, prioritization can be provided so that, in the event that a predetermined difference is determined between the actual slip value and the permissible slip value that is greater than a predetermined threshold value, the drive torque of the electric machine is at least temporarily controlled exclusively using the target value control.The control of the drive torque of the electric machine using the target value control can be continued for a predetermined period of time. Furthermore, after the control of the drive torque of the electric machine using the target value control has ended and the predetermined period has elapsed, the control of the drive torque of the electric machine using the closed control loop can be resumed. Pre-control can be provided in the control method. For example, a specific drive torque or a specific drive torque difference can be specified for the electric machine if the actual slip value is greater than a permissible slip value. This allows a particularly rapid return to a state with a permissible slip.

[0016] According to one embodiment, the drive torque of the electric machine is controlled in the control step. A PID controller can be used for this control of the drive torque. The PID controller is particularly suitable for feedback control of the actual slip value, since overshooting of the electric machine can be prevented by appropriately setting the PID controller coefficients, and at the same time, the actual slip value can be quickly returned to the permissible slip value. The PID controller coefficients can be determined and preset empirically.

[0017] According to one embodiment, a controller setting limit for the drive torque of the PID controller can be designed to be adjustable between a predetermined maximum value and zero. The controller setting limit for the drive torque of the PID controller is a variable with which the PID controller sets the drive torque based on a currently existing drive torque of the electric machine. The predetermined maximum value of the controller setting limit for the drive torque of the PID controller can be determined empirically. Furthermore, the predetermined maximum value for the controller setting limit can be variable and, in particular, can be set to the currently existing drive torque. With this measure, it can be achieved that the setting of the drive torque of the electric machine by the PID controller can be successively set to a value of zero, so that the actual slip value can reach the permissible slip value.Furthermore, the controller control limit can be set to a value of zero, so that the function of the PID controller can be at least temporarily disabled. This measure can ensure that the drive torque of the electric machine is controlled exclusively using the target value control discussed above.

[0018] In one embodiment, a predetermined curve including a ramp function can be used to adjust the PID controller's control limit. This embodiment achieves a smooth transition when switching the PID controller from a control limit of zero to the predetermined maximum value, or vice versa. This improves the operational reliability of the bicycle by preventing excessive drive torque gradients.

[0019] According to one embodiment, a target speed and an actual speed of the drive wheel can be considered as the target value and actual value with respect to the rotational state of the drive wheel. For considering a slipping state in a bicycle being pushed over a surface, the relationship between the peripheral speed of the drive wheel and the speed of the bicycle over the surface is useful. Furthermore, the rotational speeds of the drive wheel can be determined directly or indirectly and can be readily used for the control method.

[0020] According to one embodiment, a target rotational acceleration and an actual rotational acceleration of the drive wheel can be considered as the target value and actual value with respect to the rotational state of the drive wheel. Changing the peripheral speed of the drive wheel is useful as an alternative or in addition to considering the absolute value of the peripheral speed of the drive wheel, since a particularly fast response of the control method can be achieved.

[0021] In one embodiment, the actual value regarding the rotational state of the drive wheel can be derived from a speed signal of the electric motor of the drive device. When the control method is applied to a bicycle with a drive device in which the electric motor is coupled to the output element, which in turn is coupled to the drive wheel, the speed of the drive wheel can be deduced by determining the speed of the electric machine. For this purpose, it is particularly useful if the electric machine is coupled to the drive wheel with a predetermined gear ratio.Furthermore, it is possible to infer the speed of the drive wheel from the speed of the electric machine if the gear ratio between the electric machine and the drive wheel is variable, and at the same time the gear ratio between the electric machine and the drive wheel is known and can be made available for carrying out the control method. The control method is particularly useful for a bicycle with a drive device in which the electric machine is coupled to the output element on the output side or output side. Similarly, it can be provided that a rotational acceleration of the drive wheel can be determined from the rotational acceleration of the electric machine. Alternatively, the actual value relating to the rotational state of the drive wheel can be determined by a sensor that detects the speed of the drive wheel.

[0022] In one embodiment, the target value regarding the rotational state of the drive wheel can be derived from a directly or indirectly determinable speed of the bicycle over the ground. The speed of the bicycle over the ground can be derived from the peripheral speed of the non-driven wheel of the bicycle. For this purpose, a wheel speed sensor can be provided on the non-driven wheel, the signal from which is available for further processing. Alternatively, a speed sensor can be provided that detects the speed of the bicycle and provides a corresponding signal for further processing.

[0023] In one embodiment, the speed of the electric motor can be controlled based on the operating conditions of the bicycle. In particular, in the case of the bicycle, which may be configured as a pedelec, the pushing force of the user while pushing is determined, and the operation of the electric motor is controlled on this basis. Other operating conditions of the bicycle, including the speed of the bicycle over the ground, an input from a driver of the vehicle to control the speed of the electric motor, and the like, can be taken into account additionally or alternatively.

[0024] In one embodiment, the drive torque of the electric machine can be applied to the output element of the drive device on the output side without passing through the transmission device. The control method is particularly applicable to a bicycle with a drive device in which the electric machine is coupled to the output element and thus to the drive wheel on the output side. In this way, the speed or torque of the electric machine can be regulated or controlled using simple means in such a way that the potentially existing slip condition on the drive wheel can be reliably counteracted.

[0025] In one embodiment, the method may include a step of controlling a braking system of the bicycle based on the actual slip value toward the permissible slip value, which is lower than the actual slip value. For example, the bicycle may have an automatically actuated brake. The braking system may, for example, have an electric actuator for actuating a brake of the drive wheel. This can, for example, implement an ABS function. With the push assist function, the braking system can be used to quickly brake a spinning drive wheel in order to return to a state with sufficient traction.

[0026] According to a further aspect, a control device for a drive device for a bicycle is provided, which has input interfaces for receiving input signals and output interfaces for outputting output signals and a device for controlling an electric machine, wherein the control device is configured to carry out the method with one or more of the features discussed above. The control device can be integrated into a higher-level control device provided on the bicycle. The control device can be a separate device that can be provided on the bicycle. The control device can further be connected to an energy storage device that can be provided on the bicycle in order to supply electrical energy to the electric machine in accordance with the control method and to bring about the predetermined operating state of the electric machine.The control device may comprise a speed sensor configured to detect the speed of the bicycle over the ground.

[0027] According to a further aspect, a bicycle with a drive device for at least temporarily electrically assisting a drive of a drive wheel of the bicycle by muscle power has a control device as explained in the above aspect.

[0028] The bicycle is described above as having a front wheel and a rear wheel. Alternatively, the bicycle may have more than two, in particular three, wheels, of which at least one may be configured as a drive wheel. Fig. 1 shows a schematic view of a bicycle designed as a pedelec to which the control method according to the embodiments is applicable; Fig. 2 shows an exemplary drive device used in the Fig. 1 and to which the control method according to the embodiments is applicable; Fig. 3 shows a schematic representation of a flow chart of the control method in one embodiment.

[0029] Fig. 1 shows a schematic representation of a bicycle 1 to which embodiments of the control method are applicable. Fig. The bicycle 1 shown in Figure 1 is merely an example and serves to explain the functionality in connection with the control method.

[0030] The Fig. The bicycle 1 shown in Figure 1 has a frame (not explained in detail), on which a front wheel 10 as the non-driven wheel and a rear wheel 3 as the drive wheel are mounted. The bicycle 1 also has elements (likewise not explained in detail) that are typical of a bicycle, such as a saddle, a handlebar, a brake system, and other attachments, which, however, are not considered for the following explanation.

[0031] The Fig. The bicycle shown in Figure 1 is designed as a pedelec and has a drive device 2 mounted in the region of the bottom bracket position of the frame of the bicycle 1. To operate the drive device 2, an energy storage device 9 is provided on the frame of the bicycle 1, in the illustration on the down tube of the frame, which is designed as a rechargeable battery. Furthermore, the bicycle shown in Fig. 1, the bicycle 1 shown has a control device 8 which is also mounted on the frame of the bicycle 1.

[0032] The rear wheel 3, designed as a drive wheel, is coupled to the drive mechanism 2 via a drive force transmission element in the form of a chain. The drive mechanism 2 further comprises a crank mechanism 4, via which a rider of the bicycle 1 can transmit muscle power to the drive mechanism 2 while riding. When pushing, however, the user presses, for example, against the handlebars of the bicycle 1 to push the bicycle 1 forward. The drive mechanism 2 further comprises an output element 6 in the form of a chainring or a gear, which is coupled to a pinion of the rear wheel 3 via the chain. Rotation of the output element 6 is transmitted to the rear wheel 3 via the chain, so that the rear wheel 3 can be driven.

[0033] Fig. 2 shows the drive device 2 in a detailed view. The drive device 2 corresponds in structure to the one shown in Fig. 1 drive device 2 mounted on the bicycle 1. As in Fig. As can be seen in Figure 2, the drive device 2, housed in a housing, has an electric machine 7. The electric machine 7 can be operated using the electrical energy stored in the energy storage device 9. The operation of the electric machine 7 using the electrical energy stored in the energy storage device 9 is carried out by the control device 8. In this respect, the control device 8, the energy storage device 9, and the electric machine 7 are electrically and, if necessary, signal-linked to one another.

[0034] The electric machine 7 serves to apply drive power to the output element 6 of the drive device 2. In particular, a rotation of an output shaft of the electric machine 7 is transmitted with a defined transmission ratio to the output element 6 and subsequently to the drive wheel 3. During normal driving operation, the electric machine 7 serves to electrically assist the muscle power introduced into the drive device 2 by the crank device 4. The muscle power introduced into the drive device 2 via the crank device 4 is transmitted to the output element 6 via a transmission device 5 provided in the drive device 2. In this respect, the drive force of the electric machine 7 and the muscle power introduced via the crank device 4 are combined by the drive device 2, and the combined drive force is transmitted to the rear wheel 3.In addition, a push-assist mode can be activated, in which the drive device 2 assists the user in pushing the bicycle. The electric motor 7 applies a drive force to the rear wheel 3, which assists the rider in pushing the bicycle 1 by driving the rear wheel 3. The control method used to prevent slippage is explained below.

[0035] The Fig. The transmission device 5 shown schematically in Figure 2 is designed in the present embodiment as a continuously variable transmission with which the gear ratio between the rotational speed of the crank device 4 and the output element 6 can be continuously and variably adjusted. In this context, a system structure not shown in detail is used in which a second electric machine is coupled to the crank device 4 for speed superposition. It should be noted that in the present embodiment, the electric machine 7 is coupled on the output side or output side, which means that the rotation of the electric machine 7 is transmitted to the output element 6 without passing through the transmission device 5. In this respect, a predetermined relationship exists between the rotational speed of the electric machine 7 and the rotational speed of the rear wheel 3, at least in an operating state in which the rear wheel 3 is driven.

[0036] The Fig. The electric machine 7 shown in Figure 2 is operated by the control device 8 via corresponding electrical circuits. In particular, the speed of the electric machine 7 is controlled as a function of the operating states of the bicycle 1. For example, the speed of the electric machine 7 is controlled as a function of the speed of the crank mechanism 4 during operation of the bicycle 1, so that the assistance of the drive of the bicycle 1 by the electric machine 7 is consistent with the drive of the crank mechanism 4 by muscle power. Thus, the drive of the pedelec is assisted by the electric machine 7 when muscle power is introduced into the crank mechanism 4. When the pushing assistance is activated, on the other hand, a fixed drive torque or a drive torque that can be varied by the user is generated by the electric machine 7, for example, in order to assist the user in pushing the bicycle 1.Alternatively, when the push assist is activated, the electric motor 7 is operated, for example, at a fixed or user-variable drive speed to assist the user in pushing the bicycle 1. In principle, a maximum pushing speed can also be considered. The strength of the push assist can also be specified based on recorded values, such as the user's pushing force, provided the actual slip value is less than a permissible slip value.

[0037] The Fig. The electric machine 7 shown in Figure 2 has a signal output from which the rotational speed of an output shaft of the electric machine 7 can be derived. This signal output is coupled to a signal input of the control device 8. This signal provides the control device 8 with information regarding the current rotational speed of the electric machine 7 at any time. Furthermore, in the present embodiment, the drive device 2 has a sensor that is not relevant to the present control method, which sensor detects the rotational speed of the crank device 4 and provides a corresponding signal to the control device 8. Furthermore, in the present embodiment, a rotational speed sensor is provided that detects the rotational speed of the front wheel 10, which is designed as a non-driven wheel. This signal regarding the rotational speed of the front wheel 10 is also provided to the control device 8.Using this signal, the control device 8 can determine the speed of the bicycle 1 over the ground at any time, assuming that the front wheel 10 has a circumferential speed corresponding to the speed of the bicycle 1 over the ground. In a modified embodiment, a speed sensor is provided on the bicycle 1 to detect the speed of the bicycle 1. For example, this can be an acceleration sensor or GPS receiver.

[0038] In the following, an embodiment of the control method based on Fig. 3 described. In Fig.Figure 3 is a schematic flowchart illustrating steps of the control method according to this embodiment. It should be noted that in a separate control system not shown here, the speed of the bicycle 1 is controlled based on the rotational speed of the electric machine 7 in relation to the operating state.

[0039] When the push assist of the bicycle 1 and an anti-skid control system are activated, the drive torque of the electric motor 7 is regulated or controlled in a continuously performed process, taking into account any slip that may potentially occur on the rear wheel 3 of the bicycle 1. For this purpose, in a step S1, an actual slip value on the drive wheel 3 is first detected based on a deviation between a target value and an actual value with respect to the rotational state of the drive wheel 3. For this purpose, in the present embodiment, the control device 8 first determines the current speed of the bicycle 1 based on the detected rotational speed of the front wheel 10.Provided that the peripheral speed of the front wheel 10 sufficiently accurately reflects the speed of the bicycle 1, the peripheral speed of the rear wheel 3 can then be evaluated to determine whether a deviation exists, taking into account the detected speed of the bicycle 1. As described above, the peripheral speed of the rear wheel 3 is determined by determining the rotational speed of the electric machine 7 by the control device 8.

[0040] From the difference between the peripheral speed of the rear wheel 3 and the peripheral speed of the front wheel 10, which represents the speed of the bicycle 1 over the ground, it can be determined whether slippage exists between the rear wheel 3 and the ground. In the present embodiment, a value referred to as the slip value is determined from the differences between the peripheral speed of the rear wheel 3 and the peripheral speed of the front wheel 10.

[0041] Due to the fact that a certain amount of slip of the rear wheel 3 can be considered permissible during pushing, it is first checked whether the detected slip value is greater than the permissible slip value or not. In the event that the detected slip value, namely the actual slip value, is greater than the permissible slip value, the difference between the actual slip value and the permissible slip value is determined in step S2. Based on this difference, the drive torque of the electric machine 7 is adjusted in step S2 using a PID control loop. In particular, in this embodiment, starting from the current drive torque of the electric machine specified by the control device 8, a reduction in the drive torque of the electric machine is specified by the PID control loop with a predetermined profile depending on the difference between the actual slip value and the permissible slip value.In the present embodiment, the parameters of the PID control loop are preset in such a way that overshoot of the control of the drive torque of the electric machine is avoided and, at the same time, the actual slip value can be reduced to or below the permissible slip value with a fast response.

[0042] Due to the control carried out in step S2 using a closed control loop, the slip state of the bicycle 1 can thus be reduced or eliminated on the basis of a targeted reduction of the drive torque of the electric machine 7.

[0043] In parallel with the control of the drive torque of the electric machine 7 on the basis of step S2 using the closed control loop, in step S3 the drive torque of the electric machine is additionally adjusted using a target value control in the form of a feedforward control. For this purpose, in step S3, the actual slip value detected in step S1 is first compared with the permissible slip value. If a predetermined difference is detected between the actual slip value and the permissible slip value, namely if the actual slip value is greater than the permissible slip value by a predetermined amount, the drive torque of the electric machine 7 is adjusted such that a reduced drive force is present at the rear wheel 3 and thus the actual slip value is reduced.For this purpose, a target value control is used in which the reduction of the drive torque of the electric machine is taken into account on the basis of the characteristics of the bicycle 1 to which the target value control is applied.

[0044] Thus, in step S3, after detecting a predetermined difference between the actual slip value and the permissible slip value, the drive torque of the electric machine is reduced based on the current drive torque of the electric machine 7. In the present embodiment, this reduction uses a time-dependent curve for reducing the drive torque of the electric machine 7, which corresponds to a time-dependent ramp with a negative gradient. As soon as the predetermined difference between the actual slip value and the permissible slip value is again undershot, the target value control is terminated, and the electric machine 7 is operated with the drive torque present at that time.

[0045] According to the basic concept of the control method according to the present embodiment, the advantages of using a closed control loop in the form of a PID controller and a target value controller are combined. The use of a closed control loop offers very precise adjustment of the actual slip value to the target slip value in the form of the predetermined additional slip value, whereby the PID controller used is naturally subject to a certain delay in response. However, since, for example, when pushing the bicycle 1 on slippery, steep ground, direct intervention in the operation of the drive device 2 is necessary to maintain riding safety, for example to prevent the rear wheel 3 from skidding with the corresponding consequences, the target value controller executed in step S2 is superimposed on the closed-loop control executed in step S3.As a result, the target value control used in step S3, with its correspondingly rapid response, can increase the safety of the bicycle 1, particularly on slippery surfaces, since the actual slip value can be reduced so significantly in fractions of a second that the risk of a fall can be largely prevented. In addition, the precise control of the drive torque can be achieved by the closed-loop control implemented in step S3, in order to very precisely control the drive torque of the electric motor 7 to the permissible slip value.

[0046] In a further embodiment, for controlling the drive torque of the electric machine 7 using a target value control in the form of a feedforward control, a permissible slip value is specified that is greater than the permissible slip value specified for closed-loop control of the drive torque. This measure ensures that the target value control is terminated when the permissible slip value specified for the target value control is reached. In this case, the drive torque of the electric machine is subsequently controlled using the closed-loop control until the permissible slip value specified for closed-loop control is reached.Thus, in this embodiment, the time-value control with the fast response is initially used as feedforward control, followed by closed-loop control, resulting in an overall advantageous control behavior. It should be noted that for this and other embodiments, the permissible slip value specified for closed-loop control can be set to zero. In this case, the slip at rear wheel 3 can be significantly reduced.

[0047] In a further embodiment, the control parameters of the PID controller are adjustable. In particular, in the present embodiment, the controller control limit for the drive torque of the PID controller is set between a predetermined maximum value and zero. The controller control limit is the value by which the PID controller changes the currently existing drive torque of the electric machine 7. If the controller control limit is set to a value of zero, the function of the PID controller is inhibited, and in the present embodiment, only the target value control provided in step S3 is used.If the controller limit is set to the maximum value, the PID controller can reduce the currently available drive torque of the electric machine 7 to a value of zero, so that in this case, the assistance operation by the electric machine 7 is deactivated. The predetermined maximum value of the controller limit can be variably set depending on the current drive torque of the electric machine 7.

[0048] In a further embodiment, a predetermined time profile is used when adjusting the controller control limits between the predetermined maximum value and zero, which in the present embodiment is provided as a ramp. This embodiment ensures that no abrupt change in the drive torque of the electric machine 7 is generated when changing the controller control limits, which could result in an undesirable slip condition on the rear wheel 3. Reference symbol 1 bicycle 2 drive device 3 Drive wheel (rear wheel) 4 Crank device 5 Gear device 6 Output element 7 electric machine 8 Control device 9 Energy storage device 10 non-driven wheel (front wheel) S1 Detect actual slip value S2 Control drive torque (closed control loop) S3 Control drive torque (target value control) QUOTES CONTAINED IN THE DESCRIPTION

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

[0000] DE 10 2021 118 362 B3

[0002]

Claims

[1] Control method for a bicycle (1) with a drive device (2) for at least temporarily electrically driving a drive wheel (3) of the bicycle (1) for assisting in pushing the bicycle (1), wherein the drive device (2) an electric machine (7) for providing a drive torque for electrical assistance, wherein a drive torque of the electric machine (7) can be applied to an output element (6) of the drive device (2), with the following steps: - (S1) detecting an actual slip value on the drive wheel (3) on the basis of a deviation between a target value and an actual value with respect to a rotational state of the drive wheel (3); - (S2) controlling the electrical machine (7) on the basis of the actual slip value towards a permissible slip value which is lower than the actual slip value. [2] Control method for a bicycle (1) according to claim 1, characterized by that (S2) the control of the drive torque of the electric machine (7) on the basis of the actual slip value in the direction of the permissible slip value, which is lower than the actual slip value, is carried out using a closed control loop. [3] Control method for a bicycle (1) according to claim 1 or 2, characterized by that the method additionally comprises the following step: - (S3) at least temporarily controlling the drive torque of the electric machine (7) upon detection of a predetermined difference between the actual slip value and the permissible slip value in order to reduce the difference between the actual slip value and the permissible slip value using a target value control. [4] Control method for a bicycle (1) according to one of the preceding claims, characterized bythat in step (S2) of the control the drive torque of the electric machine is controlled and a PID controller is used to control the drive torque. [5] Control method for a bicycle (1) according to claim 4, characterized by that a controller setting limit for the drive torque of the PID controller can be set within a range between a predetermined maximum value and 0. [6] Control method for a bicycle (1) according to claim 5, characterized by that a predetermined curve including a ramp function is used to set the controller limit of the PID controller. [7] Control method for a bicycle (1) according to one of the preceding claims, characterized by that a target speed and an actual speed of the drive wheel (3) are taken into account as the target value and actual value with regard to the rotational state of the drive wheel (3). [8] Control method for a bicycle (1) according to one of claims 1-6, characterized by that a desired rotational acceleration and an actual rotational acceleration of the drive wheel (3) are taken into account as the desired value and actual value with regard to the rotational state of the drive wheel (3). [9] Control method for a bicycle (1) according to one of the preceding claims, characterized by that the actual value regarding the rotational state of the drive wheel (3) is derived from a speed signal of the electric machine (7) of the drive device (2). [10] Control method for a bicycle (1) according to one of the preceding claims, characterized by that the target value with regard to the rotational state of the drive wheel (3) can be derived from a directly or indirectly determinable speed of the bicycle (1) over the ground. [11] Control method for a bicycle (1) according to one of the preceding claims, characterized bythat the speed of the electric machine (7) is controlled on the basis of operating conditions of the bicycle (1). [12] Control method for a bicycle (1) according to one of the preceding claims, characterized by that the drive torque of the electric machine (7) is applied on the output side to the output element (6) of the drive device (2) without passing through the transmission device (5). [13] Control method for a bicycle (1) according to one of the preceding claims, characterized by that the method comprises a step of controlling a braking system of the bicycle (1) on the basis of the actual slip value in the direction of the permissible slip value, which is less than the actual slip value. [14] Control device (8) for a drive device (2) for a bicycle (1) with input interfaces for receiving input signals and output interfaces for outputting output signals and a device for controlling an electrical machine (7), wherein the control device (8) is designed to carry out the method according to one of the preceding claims. [15] Bicycle (1) with a drive device (2) for at least temporarily electrically driving a drive wheel (3) of the bicycle (1) when pushing the bicycle (1) and with a control device (8) according to claim 14.

Images