Method and device for controlling the drive mechanism of a pedal-operated vehicle

Abstract

A method and apparatus are claimed for controlling an additional electric or motorized drive mechanism of a vehicle that can be at least partially driven by a driver using a pedal drive mechanism. Here, a vehicle is understood to mean any type of vehicle with a pedal crank operated by a driver, such as an electric bicycle. To derive control of the drive mechanism, at least a first rotational motion variable is detected, which represents the rotational motion of the pedal or the pedaling motion of the pedal crank by the driver, particularly its changes over time. The first rotational motion variable can be detected using a single sensor or by combining sensor variables from multiple sensors. The drive mechanism is then controlled or regulated depending on a second rotational motion variable derived from the first rotational motion variable. For this purpose, at least one time constant is considered in addition to the first rotational motion representing the driver's pedaling motion, which time constant affects the delay time of the controlled or regulated drive mechanism. The essence of the invention is that a second rotational motion variable derived from a first rotational motion variable is compared with the original first rotational motion variable, and depending on the result of this comparison, the time constant used in the calculation of the second rotational motion variable is then changed.

Description

[Technical field]

[0001] The present invention relates to a method and apparatus for controlling an auxiliary drive mechanism of a vehicle that is otherwise driven by a driver using pedals. [Background technology]

[0002] The assistance of an electric bicycle by a drive mechanism, which is usually electric, is usually dependent on the pedaling frequency or pedaling torque of the rider. Here, the propulsive force is controlled by the drive mechanism depending on the pedaling speed or pedaling power. That is, due to the circular movement of the pedal crank and the usually uneven pedaling movement of the rider, a measurement variable that fluctuates around a time average value is detected for control, and the assistance by the drive mechanism is controlled or adjusted based on the measurement variable. In particular, in the case of pedaling power, the measurement variable torque takes the form of a sinusoid with strong waves.

[0003] If the assistance by the drive mechanism were adjusted directly without time delay depending on the sine curve of the strong wave detected in this way, a similarly uneven auxiliary drive or motor torque would be generated, which would be added additionally to the propulsion force generated by the rider. As a result, the reaction and movement of the e-bike would be partly jerky. Furthermore, such a direct derivation of the drive torque on an uphill road would bring about further disadvantages. For example, when the pedal position reaches a dead point (one pedal is completely up and the other pedal is completely down), no or only a very small torque is applied to the chain ring and thus to the driven rear wheel, which may result in a decrease in speed and therefore the rider may have to stop or get off the bike.

[0004] For this purpose, the drive mechanism is controlled and operated with a delay time constant that depends on the detected (wave-like) driver torque on the pedal. However, depending on the selected time constant, this method introduces inertia into the system, which may be disadvantageous in certain driving situations. That is, if a time constant that is too long is selected, for example when starting or during dynamic acceleration, it may happen that the desired assistance is realized only with a delay. Summary of the Invention [Problem to be solved by the invention]

[0005] The invention therefore seeks to propose a solution for appropriately adapting the time constants and thus the delay times of the drive mechanism to the driving situation. [Means for solving the problem]

[0006] According to the independent claims, methods and devices are claimed that are intended for controlling an additional electric or motor drive mechanism of a vehicle that can be at least partially driven by a driver using a pedal drive mechanism. Here, a vehicle should be understood to be any type of vehicle with a pedal crank operated by a driver, such as, for example, an electric bicycle. Here, in order to derive the control of the drive mechanism, it is intended that at least a first rotational motion variable is detected, the first rotational motion variable representing the rotational motion of the pedal or the pedaling motion of the pedal crank by the driver, in particular their changes over time. Here, the first rotational motion variable can be detected using a single sensor or by combining sensor variables of several sensors. The drive mechanism is then controlled or regulated depending on a second rotational motion variable obtained from the first rotational motion variable. In order to derive the second rotational motion variable, it is intended that at least one time constant is taken into account in addition to the first rotational motion variable representing the pedaling motion of the driver, which time constant influences the delay time of the drive mechanism to be controlled or regulated. Here, the essence of the invention is that a second rotational motion variable derived from a first rotational motion variable is compared with the original first rotational motion variable, and depending on the result of this comparison the time constant used for the calculation or generation of the second rotational motion variable is then changed.

[0007] The advantage of such a procedure for deriving the control or regulation of the drive mechanism is that different time constants can be used depending on the result of the derivation for the second rotational motion variable. If the difference between the two rotational motion variables is too large, the time constant can be increased or decreased to speed up or slow down the response of the drive mechanism to the thrust of the vehicle. This is particularly useful in starting situations or uphill or downhill.

[0008] In one aspect of the invention, it is contemplated that the second rotational motion variable is generated by low-pass filtering or smoothing of the first rotational motion variable, where first order low-pass filtering may be used.

[0009] The change in the time constant is in particular between two preset limit values ​​and may be continuously variable. Alternatively, however, it is also possible that a fixed time constant is preset, so that the method can select between at least two time constants. The presetting of the time constants may be stored in a database to which the method has access. The selection of the time constant may be based solely on the comparison or in conjunction with additional criteria, for example taking into account further operating data or driving dynamics parameters.

[0010] To implement the invention, it may be provided that a first time constant is selected when the first rotational motion variable exceeds a threshold value, otherwise a second time constant is selected, where it may be provided that the first time constant is smaller than the second time constant, in particular by an order of magnitude.

[0011] Here, the threshold value can be selected depending on the second rotational motion variable. In the simplest case, the threshold value corresponds to the second rotational motion variable. This selection of the threshold value allows recognition that the driver is exerting a higher pedaling requirement on the pedal than would be contemplated by the derivation of the control of the drive mechanism.

[0012] A further way to set the threshold consists in scaling the second rotational motion variable with a scaling factor or in adding a fixed or variable value to the second rotational motion variable. For example, when scaling, it can be achieved that in the case of a small pedaling requirement, i.e. in the case of a small first rotational motion variable, the sensitivity to the time constant and thus to the control change of the drive mechanism is high, whereas in the case of a high pedaling requirement, i.e. in the case of a high first rotational motion variable, a larger change in the pedaling requirement is necessary to achieve a change in the control. The same seems to be true in the case of using a variable value added to the second rotational motion variable for setting the threshold. In contrast, in the case of using an absolute or fixed value to add to the second rotational motion variable, the opposite effect is expected, since this fixed value is less important in the case of a higher second rotational motion variable than in the case of a lower second rotational motion variable.

[0013] Advantageously, the scaling factors or absolute or variable values ​​are preset depending on vehicle driving variables or driving dynamics sensor variables, in particular sensor variables that can be generated or influenced by the driver, whereby consideration of the bicycle speed or acceleration, roll, pitch angle, yaw rate, and also the bicycle or driver mass, and / or pedaling speed or pedaling frequency may also be considered.

[0014] It may further be conceivable that at least two thresholds are used, at which respectively different scaling factors or absolute or variable values ​​modify the underlying second rotational motion variable. In this case, it would be possible to select separate time constants for reaching or exceeding each threshold. Thus, for example, a third, fourth or fifth time constant may be envisaged, each of which generates a different delay time when controlling the drive mechanism. Alternatively or additionally, it may be envisaged that the time constants used are set depending on the first or second rotational motion variable.

[0015] Additionally, it may be provided that the generation of the second rotational motion variable, from which the control of the drive mechanism is derived, takes into account a further variable of the pedal actuation by the driver, which of course may also only be taken into account when the control is derived from the second rotational motion variable.

[0016] Furthermore, it is also conceivable that at least one of the time constants used is likewise varied depending on the pedal actuation variable. The actuation variable may be used to apply an offset to the second rotational motion variable. Additionally, the offset may also be selected depending on a preset time constant.

[0017] The first rotational motion variable may represent both the torque applied to the pedal by the cyclist and the pedaling frequency or cadence generated by the cyclist. Correspondingly, the actuation variable may represent another physical variable exerted or generated by the cyclist.

[0018] Further advantages become apparent from the following description of exemplary embodiments or from the dependent patent claims. [Brief description of the drawings]

[0019] [Figure 1] 1 is a block diagram that illustrates a schematic structure of an apparatus for implementing the method according to the invention; [Diagram 2] FIG. 2 shows a schematic diagram of an implementation of a first exemplary embodiment of the present invention. [Diagram 3] FIG. 2 illustrates a second exemplary embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] As already mentioned at the beginning, the control of the additional drive mechanism of a pedal vehicle, for example an electric bicycle, is usually performed depending on the actuation of the pedal by the driver, whereby both the pedaling frequency or pedaling speed and the actuation force in the form of the driver pedaling torque can be used as measures for the desired assistance by the additional thrust of the proposed drive mechanism.

[0021] In the following, according to the invention, a method and a device for improving the adaptation of the assistance by the (assisted) drive 160 depending on the driver's request shall be described. For this purpose, it is provided that a corresponding device, for example a control device 100 of a Human-Machine-Interface (HMI in English) as is common for the control of electric drives, detects various sensor variables and controls the drive 160 on the basis of these sensor variables. Here, it may be provided that the control device 100 comprises a memory 110 in which corresponding databases or variables related to the control are stored. To carry out the derivation of the control, the control device 100 detects the driver's request or the actuation of the pedal by the driver. This can be achieved using a torque sensor 120 and also using a pedaling frequency sensor 130 at the pedal crank of the bicycle.

[0022] Furthermore, further sensors 140 and / or 150 may be attached to the vehicle, the bicycle or the driver, which detect driving dynamics or driving variables, see here inter alia sensors for detecting speed, acceleration, yaw rate, roll, road gradient and even heart rate. Furthermore, it may also be possible to detect the surrounding environment of the vehicle or bicycle, for example using video sensor mechanisms or ultrasound, for example to detect other traffic participants or obstacles in the path.

[0023] Starting from the sensor variables thus obtained via the driver's actuation of the pedal crank, the control device can control the drive mechanism in such a way that an additional thrust is generated to the thrust generated by the driver using his pedaling power. Here, the assistance level, i.e. the driver's requested increase, can be preset or selected by the driver. Additional information on the driving dynamics and the operating or environmental parameters can additionally allow for an adaptation of the assistance.

[0024] In the first exemplary embodiment according to Fig. 2, first in a step or module 200, the driver torque M_in applied or generated by the driver is determined on the basis of the detected sensor variables. Typically, this is a first rotational motion variable, detected directly or indirectly using a torque sensor 120 at the pedal crank of the bicycle. Alternatively, the pedaling frequency can also be used here to derive a value relating to the current driver's wish from it. The first rotational motion variable thus determined is fed to a low-pass filter 230, which generates a second rotational motion variable M_out using a time constant T and outputs it via output 240. This second rotational motion variable is used to derive the control of the drive mechanism 160. Next, according to the invention, the setting of the time constant T is described. In this respect, in the simplest case, two time constants T_up and T_down are provided, which are correspondingly read from the memory 110, for example, via steps 210 and 220. Together with the detected first rotational motion variable M_in and the second rotational motion variable originating from the previous determination, in step 250 it is determined which of the preset time constants T_up or T_down is used for the low-pass filtering in step 230. For this purpose, in step 250 a comparison is made between the second rotational motion variable and the first rotational motion variable. If the first rotational motion variable M_in>M_out, i.e. if the driver's current pedal demand is higher than the low-pass filtered intended criterion for controlling the drive mechanism, the preset time constant T_up is selected, otherwise a further preset time constant T_down is selected. Thus, the time constant T_up is selected smaller than the time constant T_down, thereby accelerating the response of the drive mechanism to changes in the driver's wishes. Here, typically, the time constant T_up is significantly smaller than the time constant T_down, for example at least an order of magnitude smaller. Optionally, it can also be provided that a selection from several time constants can be made, for example by using several thresholds starting from the comparison between the first and second rotational motion variables.

[0025] It may further be contemplated that the time constant is retrieved or selected from a database depending on the driving dynamics or driving variables and the driver parameters. Alternatively or optionally, the time constant may take a continuous value between two extreme values ​​that are selected, set or specified depending on further boundary conditions such as the driving dynamics or driving variables.

[0026] In the second exemplary embodiment of FIG. 3, it is contemplated to utilize an additional actuation variable of the pedal crank in order to improve the derivation of the second rotational motion variable and thus provide improved maneuverability to the driver.

[0027] For this purpose, analogously to the first exemplary embodiment, in a first step 200 the driver torque M_in is determined and processed in a low-pass filter 310. The result of the low-pass filter 310 is made available to an adder 350, which makes a modified second rotational motion variable M_out available to an output module 340. As already mentioned in the first exemplary embodiment, the result of the low-pass filter 310 is made available to a step 320 for comparing the rotational motion variables M_in and M_out. Additionally, step 320 detects a further actuation variable of the pedal detected in the corresponding step 300. In this second exemplary embodiment, the pedaling frequency or cadence of the driver can be detected as the second actuation variable. An actuation variable can also be additionally used in step 320 for identifying, selecting or varying a time constant or for selecting a corresponding time constant from at least two predefined numbers of time constants. The result of the comparison in step 320 is made available both to a low-pass filter 310 according to the first exemplary embodiment and to a step 330 for determining an offset correction factor. To determine the offset correction factor in step 330, the actuation variables from step 300 and the selected, pre-set or specified time constant T from step 320 are additionally used. The offset correction factor thus determined is then sent to an adder 350 in order to generate a corrected rotational motion variable M_out, which provides the basis for controlling the drive mechanism.

[0028] By specifying an offset correction factor, the different time constants for the increase and decrease of the input torque can be even better taken into account, and thus the difference in the time constants for the increase and decrease of the input torque can be compensated for by using an additional variable representing the pedaling behavior of the driver.

[0029] Furthermore, control by such a correction factor can be adjusted more sensitively for low pedaling frequencies, with the system reacting more slowly at high pedaling frequencies. In a further exemplary embodiment, it may be provided that a scaling factor is derived in step 330, which is applied in step 360 to the second rotational movement variable generated by the low-pass filter 310 instead of the adder. Here, the scaling factor may also be determined in dependence on driving dynamics variables, driving variables or driver parameters in addition to the time constant.

Claims

1. A method for controlling a drive mechanism (160) of a pedal-operated vehicle, comprising: Detecting, using at least one first sensor (120, 130), a first rotational movement variable representative of a rotational movement of the pedal by a driver; generating a second rotational motion variable in dependence on the first rotational motion variable, a time constant and an actuation variable representative of an actuation of a pedal by the driver for controlling the drive mechanism (160), the time constant specifying a delay time of the drive mechanism (160); In the method, Varying the time constant in dependence on a comparison between a previously generated second rotational motion variable and the first rotational motion variable; the second rotational motion variable is generated using low-pass filtering (230, 310) of the first rotational motion variable; if the first rotational motion variable represents a torque applied by the driver to a pedal, the actuation variable represents a pedaling frequency produced when the driver depresses a pedal, if the first rotational motion variable represents a pedaling frequency generated by the driver when the driver depresses a pedal, the actuation variable represents a torque applied to the pedal by the driver; A method comprising:

2. The method of claim 1 , wherein the pedal vehicle is an electric bicycle.

3. 3. The method according to claim 1 or 2, characterized in that, depending on a comparison of the second rotational motion variable with the first rotational motion variable, the time constant varies between a first time constant (T_up) and a second time constant (T_down), the first time constant (T_up) and the second time constant (T_down) being preset.

4. A method for controlling a drive mechanism (160) of a pedal-operated vehicle, comprising: Detecting, using at least one first sensor (120, 130), a first rotational movement variable representative of a rotational movement of the pedal by a driver; generating a second rotational motion variable in dependence on the first rotational motion variable and a time constant for controlling the drive mechanism (160), the time constant specifying a delay time of the drive mechanism (160); In the method, when the first rotational motion variable is greater than a threshold value set depending on a previously generated second rotational motion variable, a first time constant (T_up) is selected as the time constant, and when the first rotational motion variable is equal to or less than the threshold value, a second time constant (T_down) is selected as the time constant, the first time constant being smaller than the second time constant (T_down); A method comprising:

5. The threshold value is by scaling the second rotational motion variable by a scaling factor; or Adding an absolute or variable value to the second rotational motion variable It is set, The scaling factor or the absolute value or the variable value is preset depending on driving dynamics sensor variables or driving variables of the vehicle. The method of claim 1.

6. 6. A method according to claim 4 or 5, characterized in that the first rotational movement variable represents the torque applied by the driver to a pedal or the pedaling frequency produced when the driver presses on a pedal.

7. The method according to any one of claims 4 to 6, characterized in that the second rotational movement variable is generated for controlling the drive mechanism (160) in additional dependence on an actuation variable representative of an actuation of a pedal by the driver, in that if the first rotational movement variable represents a torque applied by the driver to the pedal, the actuation variable represents a pedaling frequency generated when the driver presses on the pedal, if the first rotational motion variable represents a pedaling frequency generated by the driver when the driver depresses a pedal, the actuation variable represents a torque applied to the pedal by the driver; method.

8. 8. The method of claim 7, wherein the time constant is varied in dependence on the operating variable.

9. 9. The method according to claim 7 or 8, characterized in that for controlling the drive mechanism, the second rotational movement variable is modified with an offset, the offset being set in dependence on the actuation variables and the time constants (T_up, T_down).

10. An apparatus for controlling a drive mechanism (160) of a pedal-operated vehicle, comprising a control device (100), The control device (100) Detecting, using at least one first sensor (120, 130), a first rotational movement variable representative of a rotational movement of the pedal by a driver; 1. An apparatus for controlling the drive mechanism (160), comprising: a second rotational motion variable generated in dependence on the first rotational motion variable, a time constant and an actuation variable representative of an actuation of a pedal by the driver, the time constant specifying a delay time of the drive mechanism (160), The control device (100) performing a comparison between a previously generated second rotational motion variable and said first rotational motion variable and varying said time constant in dependence on said comparison; generating said second rotational motion variable using low pass filtering (230, 310) of said first rotational motion variable; if the first rotational motion variable represents a torque applied by the driver to a pedal, the actuation variable represents a pedaling frequency produced when the driver depresses a pedal, if the first rotational motion variable represents a pedaling frequency generated by the driver when the driver depresses a pedal, the actuation variable represents a torque applied to the pedal by the driver; An apparatus comprising:

11. An apparatus for controlling a drive mechanism (160) of a pedal-operated vehicle, comprising a control device (100), The control device (100) Detecting, using at least one first sensor (120, 130), a first rotational movement variable representative of a rotational movement of the pedal by a driver; 1. An apparatus for controlling the drive mechanism (160), comprising: generating a second rotational motion variable in dependence on the first rotational motion variable and a time constant, the time constant specifying a delay time of the drive mechanism (160), The control device (100) when the first rotational motion variable is greater than a threshold value set depending on a previously generated second rotational motion variable, a first time constant (T_up) is selected as the time constant, and when the first rotational motion variable is equal to or less than the threshold value, a second time constant (T_down) is selected as the time constant, the first time constant being smaller than the second time constant (T_down); An apparatus comprising:

12. 12. Apparatus according to claim 10 or 11, characterized in that the pedal vehicle is an electric bicycle.

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