DE102021207606A1 - Method for determining a relative air speed on a vehicle that can be operated with muscle power and/or engine power - Google Patents

Abstract

The invention relates to a method for determining a relative air speed on a vehicle (10) that can be operated with muscle power and/or motor power, in particular an electric bicycle, comprising the steps of: detecting an absolute pressure using a pressure sensor (2), determining a geodetic height of the vehicle (10) based on location data of a positioning system (6) of the vehicle (10) and/or based on movement data of the vehicle (10), the movement data being first sensor data from an inertial sensor system (7) of the vehicle (10) and second sensor data from a speed sensor (8 ) of the vehicle (10), determining a static pressure based on the determined geodetic height, and determining the air speed relative to the vehicle (10) based on the absolute pressure and the static pressure.

Description

State of the art

The present invention relates to a method for determining a relative air speed on a vehicle that can be operated with muscle power and/or engine power, a method for operating a sensor system, and a sensor system.

Sensor systems for two-wheelers, such as bicycles, are known, by means of which current information about speeds, acceleration, inclination or the like can be recorded. Furthermore, sensor systems are known by means of which an air speed, in particular in the form of a relative wind speed, can be detected. For example shows DE 10 2016 106 703 A1 such an air speed sensor. In this case, a ram air pressure is measured by means of a pitot tube and, in addition, a static pressure is also measured either at the pitot tube or at other openings. A pressure sensor is required for each.

Disclosure of Invention

• - Erfassen eines Absolutdrucks mittels eines Drucksensors,
• - Ermitteln einer geodätischen Höhe des Fahrzeugs,
• - Ermitteln eines statischen Drucks basierend auf der ermittelten geodätischen Höhe, und
• - Ermitteln der Luft-Geschwindigkeit relativ zum Fahrzeug basierend auf dem Absolutdruck und dem ermittelten statischen Druck.

The method according to the invention with the features of claim 1 is characterized in that a particularly simple and inexpensive sensor system can be used, which can also determine air speeds. This is achieved by a method for determining a relative air speed on a vehicle that can be operated with muscle power and/or motor power, preferably an electric bicycle, which comprises the following steps:

• - detecting an absolute pressure by means of a pressure sensor,
• - determining a geodetic height of the vehicle,
• - determining a static pressure based on the determined geodetic height, and
• - Determination of the air speed relative to the vehicle based on the absolute pressure and the determined static pressure.

The determination of the geodetic height is based on location data of a vehicle's location system, for example based on GPS data. This allows the geodetic height to be determined directly. Alternatively or additionally, the geodetic height is determined based on movement data of the vehicle, which includes first sensor data of an inertial sensor system of the vehicle and second sensor data of a speed sensor of the vehicle. In other words, in this case the current geodetic height is estimated based on a movement of the vehicle, preferably based on tracking the movement.

In particular, a height of the vehicle above sea level, for example above mean sea level, is regarded as the geodetic height.

The determination of the static pressure based on the determined geodetic height is preferably carried out using the barometric height formula.

The determination of the air speed relative to the vehicle and based on the absolute pressure and the calculated static pressure is preferably carried out analogously to a determination of an air speed based on a Prandtl probe.

The method thus allows in particular the use of a single pressure sensor, by means of which the absolute pressure is detected. The static pressure is calculated on the basis of additional sensors on the vehicle, which can also provide additional information about the movement of the vehicle, for example. Since only a single pressure sensor is necessary, a lightweight and space-saving configuration of a corresponding sensor system can be implemented particularly advantageously in a bicycle.

The dependent claims relate to preferred developments of the invention.

• - Nachverfolgen jeweils eines zeitlichen Verlaufs einer Geschwindigkeit und einer Neigung des Fahrzeugs, und
• - Ermitteln von zurückgelegten Höhenmetern des Fahrzeugs basierend auf den nachverfolgten zeitlichen Verläufen von Geschwindigkeit und Neigung.

The acquisition of the movement data preferably includes the following steps:

• - tracking a time course of a speed and an inclination of the vehicle, and
• - Determination of the altitude covered by the vehicle based on the tracked time courses of speed and incline.

As a result, the geodetic height based on the movement data of the vehicle, and thus also the static pressure, can be determined particularly easily and precisely.

• - Kalibrieren des ermittelten statischen Drucks basierend auf dem mittels des Drucksensors erfassten Absolutdruck. Das heißt, der Absolutdruck dient als Basis, um Abweichungen bei der Berechnung des statischen Drucks zu vermeiden oder zu verringern. Beispielsweise können solche Abweichungen in Form einer Drift mit der Zeit vorliegen, wenn der statische Druck ausschließlich über z. B. Geschwindigkeit und Neigung des Fahrzeugs berechnet würde. Vorzugsweise erfolgt das Kalibrieren in regelmäßigen Zeitintervallen, beispielsweise alle fünf Minuten, um besonders genaue Werte für die Luftgeschwindigkeit ermitteln zu können.

The method particularly preferably also includes the step:

• - Calibration of the determined static pressure based on the absolute pressure detected by the pressure sensor. That is, the absolute pressure serves as a basis to avoid or reduce deviations in the calculation of the static pressure. For example, such deviations in the form of a drift with the Time present when the static pressure is only about z. B. speed and inclination of the vehicle would be calculated. The calibration preferably takes place at regular time intervals, for example every five minutes, in order to be able to determine particularly precise values for the air speed.

The calibration preferably takes place while the vehicle is stationary. The standstill is detected based on the first sensor data from the inertial sensor system and/or based on the second sensor data from the speed sensor. In other words, the calibration is carried out under the assumption that the static pressure when stationary corresponds to the absolute pressure, since the headwind or the relative air speed when stationary is equal to zero, in particular if there is no wind. As a result, the calibration can be carried out particularly easily.

More preferably, the calibration is carried out after the vehicle has cornered with a change in direction of at least 90°, preferably at least 180°. Cornering with the corresponding change of direction is recognized based on the first sensor data. The calibration is carried out based on absolute pressure measurements recorded during cornering. In particular, the calibration is performed based on a minimum of the recorded absolute pressure readings. This can be based on the assumption that the wind is usually gusty, ie has different wind speeds and wind directions. Thus, the static pressure can also be determined at specific points in time by means of the pressure sensor, which is provided for the absolute pressure.

• - Ermitteln einer relativen Luft-Geschwindigkeit mittels des oben beschriebenen Verfahrens zum Ermitteln einer relativen Luft-Geschwindigkeit, und
• - Anzeige der ermittelten Luft-Geschwindigkeit und/oder der über einen vorbestimmten Zeitraum aufgezeichneten Luft-Geschwindigkeit mittels einer Anzeigevorrichtung.

Furthermore, the invention leads to a method for operating a sensor system, in particular a sensor system of a vehicle that can be operated with muscle power and/or motor power, preferably an electric bicycle, comprising the steps:

• - determining a relative air velocity using the method for determining a relative air velocity described above, and
• - Display of the determined air speed and/or the air speed recorded over a predetermined period of time by means of a display device.

Particularly in the case of a vehicle that is operated at least partially with muscle power, the driver of the vehicle can obtain information about the prevailing relative wind in order to be able to optimize his driving style or seating position, for example.

• - Ermitteln eines Luft-Fahrtwiderstands basierend auf der ermittelten Luft-Geschwindigkeit und basierend auf den Bewegungsdaten.

The method preferably also includes the step:

• - Determination of an air resistance based on the determined air speed and based on the movement data.

In particular, based on the movement data, a total driving resistance of the vehicle can first be determined, with the proportion based on the relative air flow then being able to be determined based on the determined air speed.

• - Ermitteln einer verbleibenden Fahrt-Reichweite des Fahrzeugs basierend auf dem ermittelten Luft-Fahrtwiderstand. Durch Berücksichtigung des Luft-Fahrtwiderstands basierend auf der ermittelten relativen Luft-Geschwindigkeit kann die Fahrt-Reichweite des Fahrzeugs, welche beispielsweise mit der aktuellen verbleibenden Akkuladung zur Verfügung steht, besonders genau ermittelt werden.

More preferably, the method also includes the step, in particular if the vehicle is an electric bicycle:

• - Determining a remaining driving range of the vehicle based on the determined air driving resistance. By taking into account the air resistance based on the determined relative air speed, the driving range of the vehicle, which is available, for example, with the currently remaining battery charge, can be determined particularly precisely.

• - Steuern einer Unterstützungsleistung einer Antriebseinheit des Fahrzeugs in Abhängigkeit des ermittelten Luft-Fahrtwiderstands. Besonders bevorzugt erfolgt das Steuern der Unterstützungsleistung zusätzlich in Abhängigkeit der ermittelten verbleibenden Fahrt-Reichweite. Dadurch kann ein besonders effizienter Betrieb des Fahrzeugs ermöglicht werden. Zudem kann ein besonders komfortabler Fahrbetrieb für den Fahrer des Fahrzeugs ermöglicht werden, da beispielsweise bei höherem Gegenwind entsprechend eine höhere Unterstützungsleistung eingestellt werden kann.

Preferably, the method further includes the step:

• - Controlling a support power of a drive unit of the vehicle depending on the determined air resistance. In a particularly preferred manner, the assistance performance is additionally controlled as a function of the remaining driving range determined. A particularly efficient operation of the vehicle can thereby be made possible. In addition, a particularly comfortable driving operation for the driver of the vehicle can be made possible, since, for example, in the event of a stronger headwind, a correspondingly higher support performance can be set.

• - Ermitteln eines Gesamt-Fahrtwiderstands basierend auf den Bewegungsdaten, und
• - Erkennen eines Verschleißes und/oder eines Defekts eines Antriebsstrangs des Fahrzeugs basierend auf dem Gesamt-Fahrtwiderstand und dem Luft-Fahrtwiderstand und den Bewegungsdaten. Das heißt, durch den ermittelten Widerstand, welcher aus der relativen Luftumströmung des Fahrzeugs resultiert, sowie aus dem Gesamt-Fahrtwiderstand, welcher bei der Fahrt des Fahrzeugs momentan vorliegt, und den aktuellen Bewegungsdaten, kann eine Diskrepanz zwischen den Widerständen, welche zu erwarten sind, abgeschätzt werden. Basierend darauf kann somit auf einfache Weise ein Verschleißzustand des Antriebsstrangs ermittelt werden, und/oder festgestellt werden, ob ein Defekt im Antriebsstrang vorliegt, welcher beispielsweise zu einem erhöhten Antriebswiderstand führt.

The method preferably also comprises the steps:

• - Determination of a total driving resistance based on the movement data, and
• - Recognition of wear and/or a defect in a drive train of the vehicle based on the total driving resistance and the air driving resistance and the movement data. That is, by the determined resistance, which results from the relative air flow around the vehicle, as well as from the total driving resistance, which is currently present when the vehicle is driving, and the current movement data, a discrepancy between the resistances that are to be expected can be estimated. Based on this, a state of wear of the drive train can be determined in a simple manner and/or it can be determined whether there is a defect in the drive train, which leads to increased drive resistance, for example.

Furthermore, the invention relates to a sensor system of a vehicle that can be operated with muscle power and/or motor power, preferably an electric bicycle, comprising a pressure sensor, a location system, for example a GPS system, an inertial sensor system, a speed sensor, and a control device. The pressure sensor is set up to detect an absolute pressure. In addition, the control device is set up to carry out the described method for determining a relative air speed and/or the described method for operating the sensor system. The sensor system is characterized by a particularly simple and cost-effective design with few parts, with the sensor system having a large range of functions. In addition, the sensor system can be designed to be particularly lightweight and space-saving.

The sensor system preferably also includes a housing component which has a pressure opening. The pressure sensor is in fluid communication with the pressure opening, the pressure opening being aligned in the direction of travel of the vehicle. As a result, when the vehicle is traveling, the absolute pressure, ie in particular a sum of static pressure and dynamic pressure, can be determined in a simple manner.

The housing component is particularly preferably at least a partial area of an on-board computer and/or a frame component and/or a battery housing and/or an engine housing of the vehicle. That is, the pressure opening can be formed at a wide variety of positions and/or components of the vehicle. As a result, a particularly simple, space-saving and cost-effective construction of the sensor system can be achieved.

The sensor system preferably also includes a display device which is set up to display the determined air speed. In particular, further information, such as the movement data, can also be displayed with the display device.

character list

• 1 eine vereinfachte schematische Ansicht eines Elektrofahrrads mit einem Sensorsystem gemäß einem bevorzugten Ausführungsbeispiel der Erfindung, und
• 2 eine Detailansicht des Sensorsystems der 1.

The invention is described below using an exemplary embodiment in conjunction with the figures. In the figures, components that are functionally the same are each identified by the same reference symbols. It shows:

• 1 a simplified schematic view of an electric bicycle with a sensor system according to a preferred embodiment of the invention, and
• 2 a detailed view of the sensor system 1 .

Preferred Embodiments of the Invention

1 shows a simplified schematic view of a vehicle 10 that can be operated with muscle power and/or engine power, with a sensor system 20 according to a preferred exemplary embodiment of the invention. The sensor system 20 is detailed in FIG 2 shown.

In the exemplary embodiment shown, the vehicle 10 is in the form of an electric bicycle which has a drive unit 14 to support the pedaling power of a driver. The drive unit 14 is supplied with electrical energy by an electrical energy store 12 .

The sensor system 20 includes a speed sensor 8 which, in the exemplary embodiment shown, detects a rotational speed of a front wheel and, based on this, determines the speed of the vehicle 10 .

In addition, the sensor system 20 (cf. 2 ) a single pressure sensor 2, a positioning system 6, an inertial sensor system 7, and a control device 4, all of which are integrated into an on-board computer on a handlebar 40 of the vehicle 10. In 2 a partial section of this unit is shown.

The on-board computer has a housing component 9 which includes a pressure opening 15 . The pressure opening 15 is aligned in the direction of travel 100 of the vehicle 10 . In detail, the pressure opening 15 is aligned in such a way that a cross-sectional area of the pressure opening 15 is arranged perpendicular to the direction of travel 100 .

The pressure opening 15 is in fluid connection with the pressure sensor 2. An absolute pressure can thus be detected by means of the pressure sensor 2. This absolute pressure corresponds to a sum of static pressure and a dynamic pressure of an air flow 5 parallel to the direction of travel 100 and in the opposite direction of the direction of travel 100. The Air flow 5 thus corresponds to a relative air flow to the vehicle 10 when the vehicle 10 is driving.

A method for determining a relative air speed on vehicle 10 can be carried out by means of control device 4 . For this purpose, the relative air speed is calculated based on the absolute pressure, which is directly detected by means of the pressure sensor 2, and based on a static pressure.

The static pressure is calculated by the control device 4 based on data from the other sensors. In detail, an instantaneous geodetic altitude of the vehicle 10 is determined and the instantaneous static pressure is calculated based on this geodetic altitude using the barometric altitude formula. As with a Prandtl probe, a speed of the air flow 5 can be determined on the basis of absolute pressure and static pressure. In particular, the air speed relative to vehicle 10 is determined by subtracting the instantaneous vehicle speed from the speed determined in this way.

In this case, the geodetic height can be determined directly based on location data which are recorded by means of the location system 6 . In this case, the geodetic height can preferably be determined at regular time intervals.

Alternatively or additionally, the geodetic height can be determined based on movement data of the vehicle 10 . The movement data includes first sensor data from the inertial sensor system 7 and second sensor data from the speed sensor 8.

Preferably, at least an inclination is recorded as the first sensor data and a speed of the vehicle 10 is recorded as the second sensor data. In detail, inclination and speed are continuously tracked.

When determining the geodetic height based on the movement data, the height meters covered by the vehicle 10 are determined based on the tracked time profiles of speed and inclination.

Since the altitude meters covered, which are determined based on inclination and speed, can be subject to a drift over time, the determined static pressure is calibrated at specified times, for example at regular intervals and/or if a predefined state is present, based on the pressure sensor 2 detected absolute pressure.

In a first embodiment, the calibration takes place when the vehicle 10 is at a standstill, the standstill of the vehicle 10 being detected on the basis of the movement data. In particular, the absolute pressure is determined during the standstill for at least a predefined period of time.

In this case, the minimum value of the absolute pressure during the predefined time period is preferably used to calibrate the static pressure. This ensures that the influence of wind is minimal. Alternatively, the absolute pressure can be used directly for calibration if this is constant for a specific period of time, for example several seconds. In this case, it can be assumed, for example, that there is no wind.

As an alternative or in addition to the calibration while the vehicle is stationary, the calibration can take place while the vehicle 10 is cornering. Cornering, during which the vehicle 10 changes direction by at least 180°, can be recognized on the basis of the movement data. In this case, the calibration is carried out on the basis of absolute pressure measurement values recorded during cornering, a minimum value of the absolute pressure preferably being used for calibrating the static pressure.

The determined air speed relative to the vehicle 10 can be used in various ways. For example, the current air speed and preferably also the air speed recorded over a certain period of time can be displayed by means of the display device 20 .

Furthermore, the control device 4 can determine different driving resistances which occur while the vehicle 10 is driving. In particular, an air travel resistance of vehicle 10 is determined based on the air speed and based on the movement data. By looking together with a total driving resistance of the vehicle 10, which is determined based on the movement data, high wear or a defect in a drive train of the vehicle 10 can be detected, for example. Furthermore, the determined air resistance can be used to determine a remaining driving range of the vehicle 10 more precisely. Based on this, a support power of the drive unit 14 of the vehicle 10 can also be controlled.

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102016106703 A1 [0002]

Claims (14)

Method for determining a relative air speed on a vehicle (10) that can be operated with muscle power and/or motor power, in particular an electric bicycle, comprising the steps: - detecting an absolute pressure by means of a pressure sensor (2), - Determining a geodetic height of the vehicle (10) based on location data of a positioning system (6) of the vehicle (10) and/or based on movement data of the vehicle (10), the movement data being first sensor data of an inertial sensor system (7) of the vehicle (10) and second sensor data from a speed sensor (8) of the vehicle (10), - determining a static pressure based on the determined geodetic height, and - Determining the air speed relative to the vehicle (10) based on the absolute pressure and the static pressure. procedure after claim 1 , wherein the acquisition of the movement data comprises: - tracking a time profile of a speed and an inclination of the vehicle (10), and - determining the altitude covered by the vehicle (10) based on the tracked time profiles of speed and inclination. A method according to any one of the preceding claims, further comprising the step of: - Calibration of the determined static pressure based on the absolute pressure detected by the pressure sensor (2). procedure after claim 3 , wherein the calibration takes place when, based on the first sensor data of the inertial sensor system (6) and/or based on the second sensor data of the speed sensor (8), a standstill of the vehicle (10) has been detected. procedure after claim 3 or 4 , wherein the calibration takes place after cornering of the vehicle (10) with a change in direction of at least 90°, preferably at least 180°, which is detected based on the first sensor data, and wherein the calibration is carried out on the basis of absolute pressure measurement values recorded during cornering. Method for operating a sensor system (20), comprising the steps: - determining a relative air speed by means of a method according to any one of the preceding claims, and - Display of the air speed determined and/or the air speed recorded over a predetermined period of time by means of a display device (30). procedure after claim 6 , further comprising the step of: - determining an air resistance of the vehicle (10) based on the determined air speed and based on the movement data. procedure after claim 7 , further comprising the step of: - determining a remaining driving range based on the determined air driving resistance. Procedure according to one of Claims 7 until 8th , further comprising the step of: - Controlling a support power of a drive unit (14) of the vehicle (10) depending on the determined air resistance, and in particular additionally depending on the determined remaining driving range. Procedure according to one of Claims 7 until 9 , further comprising the steps of: - determining a total travel resistance based on the movement data, and - detecting wear and/or a defect in a drive train of the vehicle (10) based on the total travel resistance and the air travel resistance and the movement data. Sensor system of a vehicle (10) that can be operated with muscle power and/or motor power, in particular an electric bicycle, comprising: - a pressure sensor (2), - a positioning system (6), - an inertial sensor system (7), - a speed sensor (8), and - a control device (4), - wherein the pressure sensor (2) is set up to detect an absolute pressure, and - wherein the control device (4) is set up, a method for determining a relative air speed according to one of Claims 1 until 5 and/or a method for operating the sensor system according to one of Claims 6 until 10 to perform. sensor system claim 11 , further comprising a housing component (9) which has a pressure opening (15) with which the pressure sensor (2) is in fluid communication, the pressure opening (15) being aligned in the direction of travel (100) of the vehicle (10). sensor system claim 12 , wherein the housing component (9) at least a portion of a On-board computer and/or a frame component and/or a battery housing and/or an engine housing of the vehicle (10). Sensor system according to one of Claims 11 until 13 , further comprising a display device (30) which is set up to display the determined air speed.

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