ELECTRICALLY PROPELLED TWO-WHEELED VEHICLE AND METHOD FOR ADJUSTING A DRIVE TORQUE OF AN ELECTRICALLY PROPELLED TWO-WHEELED VEHICLE

Abstract

An electrically propelled two-wheeled vehicle and a method for adjusting a drive torque of an electrically propelled two-wheeled vehicle. The electrically propelled two-wheeled vehicle includes: a sensor, based on which a pitch rate of the electrically propelled two-wheeled vehicle is ascertainable; a device for influencing a drive torque of the electrically propelled two-wheeled vehicle; and an evaluation unit configured to compare a pitch rate, which is ascertained on the basis of the sensor and represents a pitch rate of the electrically propelled two-wheeled vehicle relative to the surroundings of the two-wheeled vehicle, to a predefined, static pitch rate threshold value, and configured to reduce a drive torque acting upon a drive train of the electrically propelled two-wheeled vehicle using a predefined amplification factor, if a pitch rate generated by an upward movement of a front wheel of the electrically propelled two-wheeled vehicle exceeds the static pitch rate threshold value.

Claims

1. An electrically propelled two-wheeled vehicle, comprising: a sensor, on the basis of which a pitch rate of the electrically propelled two-wheeled vehicle is ascertainable; a device configured to influence a drive torque of the electrically propelled two-wheeled vehicle; and an evaluation unit configured to: compare the pitch rate, which is ascertained on the basis of the sensor and represents a pitch rate of the electrically propelled two-wheeled vehicle relative to surroundings of the electrically propelled two-wheeled vehicle, to a predefined, static pitch rate threshold value; and reduce the drive torque acting upon a drive train of the electrically propelled two-wheeled vehicle using a predefined amplification factor, if a pitch rate generated by an upward movement of a front wheel of the electrically propelled two-wheeled vehicle exceeds the static pitch rate threshold value.

2. The electrically propelled two-wheeled vehicle as recited in claim 1, wherein the sensor is: a rate-of-rotation sensor of the electrically propelled two-wheeled vehicle; and/or an acceleration sensor of the electrically propelled two-wheeled vehicle; and/or a spring deflection sensor of a suspension fork of the electrically propelled two-wheeled vehicle; and/or a distance sensor of the electrically propelled two-wheeled vehicle; and/or a vibration sensor of the electrically propelled two-wheeled vehicle; and/or an inclination sensor of the electrically propelled two-wheeled vehicle; and/or a sensor for satellite-aided navigation of the electrically propelled two-wheeled vehicle; and/or an air pressure sensor of the electrically propelled two-wheeled vehicle.

3. The electrically propelled two-wheeled vehicle as recited in claim 1, further comprising at least one longitudinal speed sensor, wherein: the longitudinal speed sensor is configured to measure a longitudinal speed of the electrically propelled two-wheeled vehicle; and the evaluation unit is configured to ascertain the amplification factor as a function of a longitudinal speed determined on the basis of the longitudinal speed sensor.

4. The electrically propelled two-wheeled vehicle as recited in claim 1, wherein: the device for influencing the drive torque is an electric drive motor of the electrically propelled two-wheeled vehicle, and/or a brake system of the electrically propelled two-wheeled vehicle, and/or a drive train gear ratio of the electrically propelled two-wheeled vehicle; and/or the electrically propelled two-wheeled vehicle is an electric bicycle or a pedelec or an electric motorcycle or or an electric scooter.

5. A method for adjusting a drive torque of an electrically propelled two-wheeled vehicle, comprising the following steps: comparing a pitch rate, which represents a pitch rate of the electrically propelled two-wheeled vehicle relative to surroundings of the electrically propelled two-wheeled vehicle, to a predefined, static pitch rate threshold value; and reducing a drive torque acting upon a drive train of the electrically propelled two-wheeled vehicle using a predefined amplification factor, when a pitch rate generated by an upward movement of a front wheel of the electrically propelled two-wheeled vehicle exceeds the predefined pitch rate threshold value.

6. The method as recited in claim 5, wherein the pitch rate is controlled in view of a predefined setpoint pitch rate value.

7. The method as recited in claim 5, wherein the amplification factor is ascertained as a function of a longitudinal speed, which is measured using a longitudinal speed sensor of the electrically propelled two-wheeled vehicle.

8. The method as recited in claim 5, wherein the amplification factor is ascertained based on: a rate of rotation about a transverse axis and/or about a vertical axis and/or about a longitudinal axis; and/or an acceleration in the direction of the transverse axis and/or the vertical axis and/or the longitudinal axis; and/or a wheel speed; and/or a change in the wheel speed; and/or an odometric value; and/or a gear, currently used, of a gearshift mechanism of the electrically propelled two-wheeled vehicle.

9. The method as recited in claim 5, further comprising: predicting future lift-off of a front wheel of the electrically propelled two-wheeled vehicle from a road surface, while the front wheel is in contact with a road surface; and adjusting a setpoint drive torque as a function of a result of the prediction.

10. The method as recited in claim 5, wherein a specific accuracy of rate-of-rotation signals and/or of acceleration signals and/or of odometric signals is improved, using a sensor fusion algorithm, in that the sensor fusion algorithm merges a portion or all of the rate-of-rotation signals and/or the acceleration signals and/or the odometric signals with each other.

11. The method as recited in claim 5, further comprising: ascertaining a desired lift-off of the front wheel of the electrically propelled two-wheeled vehicle from a road surface based on predefined criteria; and preventing the drive torque from decreasing, and aiding the lift-off of the front wheel, based on the predefined criteria being satisfied.

12. The method as recited in claim 5, wherein the drive torque is reduced only when: a user enables the reduction in the drive torque; and/or a current longitudinal acceleration of the electrically propelled two-wheeled vehicle exceeds a predefined longitudinal acceleration threshold value; and/or the pitch rate exceeds a predefined dynamic pitch rate threshold value, which in ascertained as a function of an expected, maximum change in gradient of a road surface in an area of the electrically propelled two-wheeled vehicle; a current longitudinal speed of the electrically propelled two-wheeled vehicle; and a wheel base of the electrically propelled two-wheeled vehicle.

13. The method as recited in claim 5, wherein values of specific setpoint drive torques ascertained based on the amplification factor are: smoothed using filtering; and/or limited using a predefined setpoint value limiter in such a manner, that only a reduction in the drive torque is rendered possible.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In the following, exemplary embodiments of the present invention are described in detail with reference to the figures.

[0025] FIG. 1 shows a schematic representation of an electrically propelled two-wheeled vehicle according to a first exemplary embodiment of the present invention.

[0026] FIG. 2 shows a signal flow diagram for illustrating a method of the present invention for adjusting a drive torque of an electrically propelled two-wheeled vehicle according to a second exemplary embodiment of the present invention.

[0027] FIG. 3 shows a signal flow diagram for illustrating a method of the present invention for adjusting a drive torque of an electrically propelled two-wheeled vehicle according to a third exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0028] With reference to FIG. 1, a electrically propelled two-wheeled vehicle of the present invention, which takes, in this case, the form of an electric bicycle (also referred to as an “e-bike”), is described below in accordance with a first preferred exemplary embodiment of the present invention.

[0029] As is shown in FIG. 1, the electric bicycle includes a rate-of-rotation sensor 10, which is configured to measured rotations of the electric bicycle about a transverse axis, about a longitudinal axis, and about a vertical axis of the electric bicycle.

[0030] In addition, the electric bicycle includes a wheel speed sensor 15, which is situated on a frame of the electric bicycle, near a rear wheel 130, and which is configured to generate a wheel speed pulse with each full revolution of rear wheel 130.

[0031] In addition, the electric bicycle has an electric motor 20, which is configured to influence a drive torque T of the electric bicycle. Electric motor 20 is supplied with electric power with the aid of a battery 25 of the electric bicycle.

[0032] In addition, the electric bicycle includes an evaluation unit 30, which takes, in this case, the form of a microcontroller, and which is connected to rate-of-rotation sensor 10, wheel speed sensor 15 and electric motor 20 (and/or to an unshown control unit of electric motor 20) in a manner allowing information to be exchanged.

[0033] In this manner, evaluation unit 30 is able to ascertain a pitch rate {dot over (θ)} of the electric bicycle from an information item about a rotation of the electric bicycle about the transverse axis and an information item about the rotation of the electric bicycle about the vertical axis, which are each provided by rate-of-rotation sensor 10; the pitch rate of the electric bicycle representing a pitch rate {dot over (θ)} of the electric bicycle relative to the horizon.

[0034] In addition, evaluation unit 30 is able to ascertain a longitudinal speed v.sub.x of the electric bicycle on the basis of the wheel speed pulses of wheel speed sensor 15.

[0035] Evaluation unit 30 is additionally configured to compare ascertained pitch rate {dot over (θ)} to a predefined, static pitch rate threshold value THR1, which is stored in a storage unit (not shown) that is connected to evaluation unit 30 so as to be able to exchange information.

[0036] In addition, evaluation unit 30 is configured to reduce the drive torque T acting upon a drive train of the electric bicycle, with the aid of a predefined amplification factor F, if a pitch rate {dot over (θ)} (a negative value) generated by an upward movement of a front wheel 120 of the electric bicycle exceeds static pitch rate threshold value THR1 in the negative direction.

[0037] The predefined amplification factor F used in this case is ascertained with the aid of evaluation unit 30 as a function of, in addition, the longitudinal speed v.sub.x determined on the basis of wheel speed sensor 15. In this exemplary embodiment, a look-up table is used for this, in which for specific longitudinal speed values and/or ranges of longitudinal speed values, in each instance, corresponding, predefined amplification factors F are stored, which are selected and used by evaluation unit 30 in accordance with current longitudinal speed v.sub.x.

[0038] In light of the description of the first exemplary embodiment, it is apparent that lift-off of front wheel 120 of the electric bicycle is reduced or even prevented in a particularly reliable manner. In addition, the use of the pitch rate according to the present invention prevents, inter alia, existing roadway gradients from having a lasting effect on a reduction in the drive torque. In addition, by taking longitudinal speed v.sub.x into account, the drive torque is advantageously reduced mainly only in situations, in which there is actually a risk of lift-off of the front wheel (that is, in ranges of low speeds).

[0039] FIG. 2 shows a signal flow diagram to illustrate a method of the present invention for adjusting a drive torque of an electrically propelled two-wheeled vehicle, which is, in this case, an electric bicycle, according to a second exemplary embodiment of the present invention.

[0040] It should be pointed out that the logic circuit forming the basis of the signal flow diagram is implemented in the form of a computer program, which is executed with the aid of an evaluation unit 30 of the present invention.

[0041] In a first step of the method according to the present invention, a pitch rate {dot over (θ)}, which represents a pitch rate {dot over (θ)} of the electric bicycle relative to the horizon, and which is ascertained on the basis of signals of a 3-D rate-of-rotation sensor of the bicycle, is compared to a predefined, static pitch rate threshold value THR1.

[0042] In a second step of the method according to the present invention, a drive torque T acting upon a drive train of the electrically propelled two-wheeled vehicle is reduced with the aid of a predefined amplification factor F, if a pitch rate {dot over (θ)} generated by an upward movement of a front wheel 120 of the electric bicycle exceeds predefined pitch rate threshold value THR1.

[0043] For this, in this exemplary embodiment, 3-D angular speed signals ω.sub.x, ω.sub.y, and ω.sub.z of a rate-of-rotation sensor 10, 3-D acceleration signals a.sub.x, a.sub.y, a.sub.z of an acceleration sensor (not shown), and an odometric signal S.sub.x of an odometric sensor (not shown), which takes the form, for example, of a wheel speed sensor 15, are received by a main computational part 35 of the signal flow diagram.

[0044] On the basis of angular speed signals ω.sub.x, ω.sub.y, ω.sub.z, acceleration signals a.sub.x, a.sub.y, a.sub.z, and odometric signal S.sub.x, main computational part 35 is configured to ascertain, inter alia, a particularly accurate pitch rate {dot over (θ)}, using a sensor fusion algorithm, which employs Kalman filtering; the pitch rate representing a pitch rate {dot over (θ)} independent of cornering.

[0045] Ascertained pitch rate {dot over (θ)} is subsequently compared to a pitch rate threshold value 110, which corresponds to a value of 0°/s in this case, in order to prevent the front wheel of the electric bicycle from lifting off.

[0046] In addition, main computational part 35 is configured to determine an amplification factor F and a precontrol signal FF on the basis of signals mentioned above and on the basis of a current drive torque T of the electric bicycle.

[0047] In particular, amplification factor F is calculated as a function of a longitudinal speed v.sub.x of the electric bicycle, which is ascertainable with a particular accuracy on the basis of the above-described sensor fusion algorithm, as well.

[0048] Amplification factor F is calculated in such a manner, that multiplication of the amplification factor by pitch rate {dot over (θ)}, which has been compared to pitch rate threshold value 110, yields a reduction torque, which is subtracted from the drive torque T currently present, in order to obtain a setpoint drive torque TT, which is used for controlling an assisting motor 20 of the electric bicycle.

[0049] Precontrol signal FF results from a prediction logic circuit of main computational part 35; the prediction logic circuit being able to predict future lift-off of a front wheel 120 of the electric bicycle from a road surface, while front wheel 120 is still in contact with the road surface. Precontrol signal FF is subsequently used for adjusting setpoint drive torque TT as a function of a result of the prediction.

[0050] With the aid of a setpoint value limiter 90, it is further ensured that an ascertained value of the reduction torque does not take on any negative values, which means that during a subsequent comparison of the reduction torque with current drive torque T, no setpoint drive torque TT is yielded, which is greater than current drive torque T.

[0051] In addition, a desired lift-off of front wheel 120 from a road surface is advantageously ascertained, for example, by additionally evaluating a signal of a spring deflection sensor (not shown) of a suspension fork of the electric bicycle, on the basis of which intentional “pulling-up” of the handlebars (e.g., for riding over a curb) is ascertainable. In this case, the automatic control for preventing the front wheel from lifting off is advantageously interrupted at least in the short term, in order to allow the intentional lift-off of the front wheel. In addition, it is also possible for the desired lift-off of the front wheel to be actively assisted, by adjusting the automatic control.

[0052] One advantage of the second exemplary embodiment is, inter alia, that due to the sensor fusion algorithm, input variables used to control the drive torque on the basis of pitch rate are provided with a particularly high accuracy, and that due to the use of the prediction logic circuit, lift-off of the front wheel may be suppressed in a particularly effective manner.

[0053] FIG. 3 shows a signal flow diagram to illustrate a method of the present invention for adjusting a drive torque of an electrically propelled two-wheeled vehicle, which is, in this case, an electric bicycle, according to a third exemplary embodiment of the present invention.

[0054] Based on a current longitudinal speed v.sub.x of the electric bicycle, a speed-dependent amplification factor F is determined by the block 50 of the signal flow diagram on the basis of a look-up table; the amplification factor being multiplied subsequently by a current pitch rate {dot over (θ)} of the electric bicycle.

[0055] When drive torque control is activated, a value of a reduction torque resulting from the multiplication is initially transmitted across switch S to a low-pass filter 80, in which consecutive values of reduction torques are smoothed for increased ride comfort.

[0056] A result of the filtering by low-pass filter 80 is subsequently processed by a setpoint value limiter 90, which ensures that the values of the reduction torque only result in a reduction of a current drive torque T.

[0057] A result of setpoint value limiter 90 is subsequently used to ascertain, in block 100, a current setpoint drive torque for the electric bicycle, which is used for preventing unwanted lift-off of the front wheel.

[0058] A specific switching state of switch S is influenced by boundary conditions, which are described below and must be satisfied simultaneously by an AND operation, in order for switch S to prevent the front wheel of the electric bicycle from lifting off on the basis of a pitch rate. In this manner, any erroneous actions due to this control may be prevented in certain situations.

[0059] For this, it is necessary, first of all, for an activation signal A to represent an active state. With the aid of, for example, a user input to an operating unit of the electric bicycle, activation signal A is set to active. In this manner, a user of the electric bicycle is put in the position to manually activate and/or deactivate, as required, the prevention of lift-off of the front wheel on the basis of pitch rate.

[0060] In addition, it is necessary for pitch rate {dot over (θ)}, which, according to the definition used here, corresponds to a negative value during an upward movement of front wheel 120 of the electric bicycle, to be less than a negative value of a predefined, static pitch rate threshold value THR1. This boundary condition is intended for preventing erroneous actions on the basis of slight pitching movements of the electric bicycle, which are not caused by lift-off of the front wheel, but by, for example, pedaling, excitation from the ground, or chassis vibrations.

[0061] Furthermore, it is necessary for a longitudinal acceleration a.sub.x of the electric bicycle to be greater than a longitudinal acceleration threshold value THR2, since lift-off of the front wheel by a drive torque T is always associated with a certain longitudinal acceleration.

[0062] In addition, it is necessary for erroneous actions to be prevented in the case of changes in gradient. For this, a maximum expected change in gradient 75 is ascertained from current pitch angle θ and a value of a maximum expected gradient 70. This is multiplied by a quotient 60 of longitudinal speed v.sub.x and a wheel base of the electric bicycle. A result of this calculation, it is subsequently compared to a predefined, dynamic pitch rate threshold value THR3, which is additionally compared to current pitch rate {dot over (θ)} of the electric bicycle.

[0063] If all of the boundary conditions are satisfied, switch S is moved into a switch position, in which the above-described reduction torque is transmitted to the low-pass filter.

[0064] Otherwise, switch S is moved into a switch position, in which a predefined reduction torque of 0 Nm is transmitted to the low-pass filter, through which the automatic control of the present invention on the basis of pitch rate is deactivated.

[0065] The third exemplary embodiment provides, inter alia, the advantage that the control of the drive torque on the basis of pitch rate is only active, when specific boundary conditions for it are satisfied. In this manner, it is possible to prevent any erroneous actions by the control system and/or control actions that reduce ride comfort.