DE102022214322A1 - Redundant IMU detection of position and orientation for actuator systems in the vehicle interior using filter algorithms on IMU data - Google Patents

Abstract

The invention relates to a method for robustly determining the spatial position of a vehicle interior element (4, 5, 6, 7) that is adjustable by an electric adjustment motor, comprising the steps: - motor-related determination of a first value of a predetermined position and/or orientation specification of the element (4, 5, 6, 7) relative to the vehicle interior based on a drive-internal sensor system of the adjustment motor (S2); - redundant motor-independent determination of at least one second value of the same position and/or orientation specification of the element (4, 5, 6, 7) based on measurement data from at least one external reference sensor (IMU1-IMU4) that is arranged in the vehicle interior without a direct mechanical connection to the adjustment motor (S3); - comparing the motor-related determined first value with the motor-independently determined at least one second value and determining a deviation therebetween (S4); - plausibility check and/or correction of the first value and/or its engine-related determination algorithm depending on the determined deviation (S5), before it is subsequently used for predetermined control processes in the vehicle interior (S6).

Description

Technical area

The invention relates to a method for robustly determining the spatial position of a vehicle interior element that is adjustable by an electric adjustment motor, such as an adjustable vehicle seat or its individually adjustable components or an adjustable steering column. The respective adjustable element and the associated motor (actuator) are also referred to collectively herein as an actuator system. The invention is also directed to a correspondingly configured control unit and a corresponding computer program, machine-readable storage medium, system and a vehicle equipped therewith, in particular a motor vehicle.

Technical background

In the automotive sector, the degree of automation of driving functions has increased in recent years, as have various other auxiliary functions for the driver and other passengers, such as seat or steering column adjustment in the interior.

Due to the ever-increasing demands on automation and the resulting changes in the usage behavior of the vehicle and the vehicle users, new use cases are emerging in order to use new safety functions to handle crash scenarios in autonomous driving mode (for example with regard to seat adjustment) and to increase comfort for the occupants (for example with regard to steering column adjustment). As a result, in future vehicles, a large number of sub-functions in the vehicle that have long been known will have a high ASIL (Automotive Safety Integrity Level) value. Even actuators in the vehicle, which could previously be viewed largely in isolation as simple components, must now be understood and viewed as subsystems of this overall system due to the increasingly important interactions with the overall vehicle system and the increasing degree of automation. The associated (sub-)system behavior can be approximated by physical (or analytical) or data-based (or numerical or parametric) models. Many actuator systems use rotor position sensors, which are used, for example, to control the actuator or as a source of diagnostic information.

On the other hand, WO 2014/197312 A1 particularly for the application in which a commercial vehicle gets into a crash situation, a method for controlling an active suspension system of a vehicle seat, which comprises an actuator and an associated control system that reacts to sensor signals from a sensor system. The sensor system used is designed primarily to detect vehicle and seat accelerations that can occur in a crash. In order to detect, for example, a rollover of the vehicle, the publication proposes mounting an inertial sensor, in particular an inertial measuring unit with an acceleration sensor, on the vehicle seat. Alternatively, the use of a gyroscope is also mentioned for detecting such a vehicle rotation. Since an inertial sensor can also fail in the event of a crash, the use of a non-inertial sensor on the vehicle seat is proposed in this case, which can be attached, for example, to the stator or to the housing of the seat adjustment motor. In this case, the control system is designed to ignore the inertial sensor and to use only the sensor signals from the non-inertial sensor to move the seat upwards in the vehicle, for example to reduce the consequences of an accident for the driver in the event of a frontal impact, or conversely downwards in the event of a rollover.

Disclosure of the invention

According to the invention, a method according to claim 1 for robustly determining the spatial position of an element of a vehicle interior that can be adjusted by an electric motor, as well as a control unit set up to carry out this method, a corresponding computer program, machine-readable storage medium, motor-based adjustment and sensor system and a vehicle equipped therewith are provided according to the independent claims. Further embodiments are specified in the dependent claims. All further features and effects mentioned in the claims and the description for the method also apply in relation to the control unit, the computer program, the storage medium, the system and the vehicle, and vice versa.

According to a first aspect, a method is provided for robustly determining the spatial position of a vehicle interior element that is adjustable by an electric adjustment motor (i.e. can be moved in a controlled manner by an active motor control). The vehicle can be a motor vehicle, for example a car, but alternatively also any other land, air or water vehicle.

In the method presented here, in order to robustly determine the spatial position of the adjustable element mentioned, a first value of its required/predetermined position and/or the orientation information relative to the vehicle interior is determined based on an internal sensor system of the adjustment motor, i.e. motor-related. Using the example of an adjustable vehicle seat or an adjustable steering column, this information can be, for example, a one- to three-dimensional indication of the spatial position of a given central point and a one- to three-dimensional indication of the spatial orientation (angle indication) of a given central axis of this element, so that the respective value is determined as a one- to six-dimensional vector in relation to the usual vehicle-fixed Cartesian coordinate system. Depending on the type of attachment and the adjustment options of the element in relation to the vehicle, a higher or, conversely, reduced number of degrees of freedom of movement may have to be determined in each specific application, as shown below using the example of a vehicle seat in 3 explained.

In addition, at least one redundant second value of the same position and/or orientation information of the same element is determined based on measurement data from at least one external reference sensor that is arranged in the vehicle interior without a direct mechanical connection to the adjustment motor (for example, outside the adjustment motor on/in the element or even spatially separated from the element). This is therefore a motor-independent determination.

The first value and the at least one second value are then compared before the first value is used for predetermined control processes in the vehicle interior for which it is required. This comparison includes comparing the first value determined in relation to the engine with the at least one second value determined independently of the engine and determining any deviation between them. This allows the first value to be checked for its integrity or plausibility and, if there is a non-negligible deviation, also corrected. The same applies to the algorithm used to determine the first value.

The method presented here can, among other things, serve to ensure/fulfill increasingly strict safety and comfort requirements related to the positioning of actuators in the vehicle interior by electric drives. Particularly in view of the increasing degree of automation of the driving function but also of auxiliary functions, there may be a need to secure relative positions recorded internally in the drive compared to an absolute position. The expanded consideration from the component to the system requires dealing with the kinematics and dynamics of the system. This can be considered using simplified physical models of the system dynamics or - as suggested here - data-based using measurement data from additional external sensors.

In order to ensure that the high safety requirements described above are met in a modern vehicle, the method presented here proposes installing redundant reference sensors at many mechanically independent points in the vehicle to determine the positioning of the respective element. The internal position detection of an actuator/motor can be supplemented and verified by this motor-external sensor technology in the method and system presented.

The implementation of this solution is described here purely as an example for an automated seat adjustment, which on the one hand must maintain a safe position for the occupant in the event of a crash scenario, but on the other hand must also report its position in relation to other seats or interior elements back to the vehicle during comfort adjustments (as the control processes mentioned above). This can also be implemented, for example, for an automated steering column adjustment, the position of which must be ensured in order to meet the high safety requirements for steering systems.

One idea of the method presented here is to take into account and enable the shift in the system boundary mentioned at the beginning from an isolated actuator system (adjustable element with its adjustment motor) to a subsystem of an overall system (vehicle or its interior) also for the sensors that are used to detect position and orientation. As already mentioned, many actuator systems use a rotor position sensor or other types of internal drive sensor to control the actuator and/or to diagnose it. However, if the actuator is now understood as a subsystem of a larger overall system due to the ever-increasing level of automation in the vehicle, this internal drive sensor may not be sufficient to detect the position or orientation of the overall system of which the actuator is a part with sufficient accuracy. In order to make the motor-related position and orientation detection of the actuator system more robust and reliable for these new, higher requirements, it is proposed here to control and/or interpret it by redundantly detecting the same position and orientation information using a physically independent sensor system in the form of at least one motor-external reference sensor. and to correct it immediately if a relevant deviation is detected.

As already mentioned, the drive-internal sensor system of the variable speed motor can be designed, for example, as a rotor position sensor system that directly measures a rotation rate (in other words, rotational speed) and/or a rotation angle and/or a torque of a rotor shaft of the variable speed motor or determines it from a direct measurement of another rotor position measurement variable. From this, the first value of the above-mentioned position and/or orientation information of the element is determined by the associated motor-related determination algorithm.

According to one embodiment, the reference sensor or at least one of the multiple reference sensors is designed as an inertial sensor (also known as an inertial sensor), such as an acceleration sensor or yaw rate sensor. In particular, this can be an inertial measurement unit (also known as IMU), i.e. a spatial combination of multiple inertial sensors such as acceleration and yaw rate sensors. In particular, in combination with the above drive-internal sensor system in the form of a rotor position sensor system, not only relative but also absolute values for the position and orientation of the relevant element in the vehicle interior can be determined in a reliable and robust manner in this embodiment.

According to one embodiment, the said correction of the first value and/or its engine-related determination algorithm is only carried out using the at least one engine-independently determined second value if the determined deviation exceeds a predetermined discrepancy threshold value. This allows the overall computational effort and the associated time and energy consumption to be reduced.

According to one embodiment, the at least one second value and/or the first value is determined, in particular estimated, by applying a predetermined (fusion) filter algorithm to the measurement data of the at least one external reference sensor and/or the internal drive sensor of the adjustment motor. For example, the application of an IMU fusion filter algorithm for "fusing" the measurement data of an acceleration sensor and a rotation rate sensor in a manner known per se enables an estimation of an orientation of the measurement object with a required precision, as described in more detail below.

The (fusion) filter algorithm mentioned can estimate the orientation of the element to be determined, in particular on the basis of measurement data without an explicit modeling of the respective system dynamics, such as when applying a complementary filter. Alternatively or additionally, the (fusion) filter algorithm mentioned can estimate the orientation of the element to be determined on the basis of measurement data using an explicit dynamic model of the respective system, such as when applying a Bayesian filter, in particular a Kalman filter.

In a specific embodiment, the at least one external reference sensor comprises at least one reference sensor that is permanently connected to the element, in particular one reference sensor in or on several independently adjustable components of the element (such as in/on a seat surface/seat pan and a backrest of a vehicle seat). Alternatively or additionally, the at least one external reference sensor can comprise at least one reference sensor that is attached in the vehicle interior without a direct mechanical connection to the element (such as in the vehicle floor or by using a sensor that is already present in an airbag). This can significantly increase the precision, simplicity and/or robustness of the method.

The mentioned element of the vehicle interior can, for example, be a vehicle seat that is adjustable as a whole relative to the vehicle or its individually adjustable component such as a backrest, seat, armrest or headrest. In principle, however, it can also be any other adjustable element of the vehicle interior, such as an adjustable steering column, a sunroof, a lowerable vehicle window, a movable display device and much more.

According to a specific embodiment, the element mentioned can have several independent translation and/or rotation axes (which are collectively and abstractly referred to herein as different "adjustment planes" of the element), each with an associated electric adjustment motor for adjusting the element along the respective translation axis or around the respective rotation axis. In this embodiment, the method presented here is carried out for each of these translation and/or rotation axes of the element, i.e. the respective associated adjustment motor (basically independently of one another).

According to a further aspect, a control unit is provided which comprises a processor (for example a microprocessor) which is designed to carry out a method presented here. The control unit can, for example, be integrated in the relevant element itself or at another location - for example in a central control unit - in the vehicle. According to further aspects, a computer program with commands which, when the computer program is executed in a control unit or a computer, cause the latter to carry out the method mentioned, as well as a machine-readable storage medium on which such a computer program is stored, are provided.

According to a further aspect, a motor-based adjustment and sensor system is provided for a vehicle. This system comprises at least one adjustable vehicle interior element. The system also comprises an associated electric adjustment motor for one or more independent translation and/or rotation axes of each of these elements, wherein the respective motor comprises a drive-internal sensor system on the basis of which a first value of a predetermined position and/or orientation specification of the element relative to the vehicle interior can be determined. The system also comprises the above control unit, which is designed and set up to carry out the method presented here for each of these motors.

According to a further aspect, a vehicle is provided which is equipped with such a system. It can in particular be a motor vehicle, for example a car, but alternatively also any other land, air or water vehicle.

• Eine bestehende, interne Relativpositionserfassung eines durch elektrische Motoren angetriebenen Aktorsystems im Fahrzeug (z.B. Lenksäulenverstellung/Sitzverstellung durch elektrische Kleinmotoren jeweils mit Rotorlagepositionssensorik) wird erweitert um die Messdaten einer IMU (Inertial Measurement Unit, also die Kombination von Drehraten- und Beschleunigungssensor). Die hier vorgeschlagenen Filteralgorithmen nutzen die Messdaten der IMU, die zu einer Position fusioniert werden können, um die systemintern ermittelten Relativpositionen zu korrigieren oder plausibilisieren. Sie liefern somit Feedback über die Position, das für die Regelung und Planung des Systemverhaltens benötigt wird. Dieses Prinzip lässt sich insbesondere auch auf Systeme mit komplexer Kinematik anwenden, wie weiter unten genauer erläutert wird.

The method and system presented here is explained below using further possible implementation details and design variants:

• An existing, internal relative position detection system of an actuator system in the vehicle driven by electric motors (e.g. steering column adjustment/seat adjustment by small electric motors, each with rotor position sensors) is expanded to include the measurement data of an IMU (Inertial Measurement Unit, i.e. the combination of yaw rate and acceleration sensor). The filter algorithms proposed here use the measurement data of the IMU, which can be merged into a position in order to correct or verify the plausibility of the relative positions determined internally in the system. They thus provide feedback on the position, which is required for controlling and planning the system behavior. This principle can also be applied in particular to systems with complex kinematics, as explained in more detail below.

1. a) Die Integrität der ermittelten Position lässt sich zu jedem Zeitpunkt bestimmen, sowohl für stationäres als auch für transientes Systemverhalten. Schlägt die Plausibilisierung fehl, also sind die erwarteten Werte der internen Messung (hierin „erste Werte“ genannt) weit entfernt von denen der externen Sensorik (hierin „zweite Werte“ genannt), kann das als möglicher Fehler frühzeitig erkannt und ans Fahrzeug gemeldet werden.
2. b) Eine Abstraktion der Positionsbestimmung von kinematischem/dynamischem Modell des Gesamtsystems („Baukastenprinzip“) ist beim vorliegenden Verfahren/System möglich: Fusionsfilteralgorithmus muss nicht auf neue Systeme angepasst werden, lediglich sinnvolle neue Positionen für Referenz-IMUs gefunden werden.
3. c) Durch die Anbringung der Referenzsensoren außerhalb der elektrischen Antriebe lässt sich das Einhalten einer geplanten Trajektorie des Elements besser kontrollieren, da Störeinflüsse wegfallen, die bei der antriebsinternen Sensorik eine Rolle spielen können. Dies erhöht die durch das System erfüllbaren Safety-Anforderungen bezüglich der Positionierung.
4. d) Ebenso weist eine Abweichung von der geplanten Trajektorie bereits auf einen beginnenden Einklemmfall (Körperteil oder Hindernis) hin, noch bevor die interne Positionserfassung des Motors dies detektieren kann. (Grund: das Drehmoment am Rotor steigt erst merklich an, wenn die Elemente mit hoher Nachgiebigkeit in der Wirkkette von der Einklemmfläche bis zum Rotor bereits deformiert sind.) Sowohl bei Lenksäulenverstellungen als auch bei Sitzverstellungen ist der Insassenschutz, insbesondere der Aspekt Einklemmschutz, mit einem hohen ASIL-Wert - oft ASIL D - belegt. Die hier beschriebene externe Absolutsensorik und ihre algorithmische Umsetzung liefert hier die Redundanz, die für die Dekomposition eines Safety-Goals genutzt werden kann.
5. e) In einer beispielhaften Ausführung in einem automatisierten Fahrzeugsitz oder einer automatisierten Lenksäulenverstellung führt die hierin vorgestellte Lösung mit der redundanten externer Sensorik zur Unabhängigkeit von der strukturspezifischen Kinematik. Dies ermöglicht einen reduzierten RechenAufwand, da die Herleitung und Parametrierung des kinematischen Modells entfällt. Speziell die Parametrierung enthält üblicherweise hohe Unsicherheiten und stark vereinfachende Annahmen (beispielsweise die Modellierung der Reibparameter der umgebenden Struktur).
6. f) In einer beispielhaften Ausführung von Filtern, die die Dynamik des Systems explizit modellieren (z. B. Kalman-Filter): Vorhersagen basierend auf einer bisherigen Trajektorie sind möglich, auch wenn die interne Messung kurzzeitig nicht zur Verfügung steht.

The following advantages may arise, among others:

1. a) The integrity of the determined position can be determined at any time, both for stationary and transient system behavior. If the plausibility check fails, i.e. the expected values of the internal measurement (hereafter referred to as "first values") are far from those of the external sensors (hereafter referred to as "second values"), this can be recognized early on as a possible error and reported to the vehicle.
2. b) An abstraction of the position determination from the kinematic/dynamic model of the overall system (“modular principle”) is possible with the present method/system: The fusion filter algorithm does not have to be adapted to new systems, only meaningful new positions for reference IMUs have to be found.
3. c) By installing the reference sensors outside the electric drives, it is easier to control whether the element follows a planned trajectory, as interference that can play a role in the drive's internal sensors is eliminated. This increases the safety requirements that the system can meet with regard to positioning.
4. d) Likewise, a deviation from the planned trajectory already indicates an incipient entrapment (body part or obstacle) before the internal position detection of the motor can detect it. (Reason: the torque on the rotor only increases noticeably when the elements with high flexibility in the chain of action from the entrapment surface to the rotor are already deformed.) In both steering column adjustments and seat adjustments, occupant protection, in particular the aspect of entrapment protection, is assigned a high ASIL value - often ASIL D. The external absolute sensor technology described here and its algorithmic implementation provide the redundancy that can be used to decompose a safety goal.
5. e) In an exemplary embodiment in an automated vehicle seat or an automated steering column adjustment, the solution presented here with the redundant external sensors leads to independence from the structure-specific kinematics. This enables a reduced computational effort, since the derivation and parameterization of the kinematic model is omitted. In particular, the parameterization usually contains high uncertainties and highly simplifying assumptions (for example, the modeling of the friction parameters of the surrounding structure).
6. f) In an exemplary implementation of filters that explicitly model the dynamics of the system (e.g. Kalman filters): Predictions based on a previous trajectory are possible, even if the internal measurement is temporarily unavailable.

The basic idea of orientation and position estimation using an IMU absolute sensor and fusion filters is to use acceleration and yaw rate sensor data in a combined estimator for improved orientation and position estimation. Estimated values from the sensor data are thus used to draw conclusions about unknown parameters.

In the static case, an accurate spatial position estimate can also be achieved purely from the acceleration data: In the absence of any movement, the norm of the measurement vector of a three-axis acceleration sensor will correspond to the acceleration due to gravity g: $$\Vert a_{mess}\Vert =\Vert \left(a_x,a_y,a_e\right)\Vert =a_{mOt}+a_{ext}+G\approx G.$$

Using this constraint and trigonometric relationships, the spatial position of the sensor relative to the Earth's gravitational field can then be determined.

However, if the sensor moves at an accelerated rate, these accelerations are also measured by the sensor and ||a _mess || can no longer be approximated with sufficient accuracy by g. This creates an error in the purely acceleration-based orientation estimation. These additional accelerations act in addition to the acceleration due to gravity g and can be caused either by the activity of the motor (a _mot ) or external accelerations (a _ext ; for example, the vehicle in which the seat is installed).

In the application described here, IMUs are to be used for position and orientation estimation of elements of a mechatronic system, e.g. a seat pan and a backrest of a seat (cf. 1 ). If these are moved by actuators, i.e. by electric motors, the rotor position sensors typically installed to control the electric motors can be used to convert the measurable accelerations a _mot of the motor into movements of the seat elements.

State-of-the-art approach: However, this traditionally requires determining kinematic and dynamic models of the seat mechanics, which is complex. In addition, the motor movements for each estimated point in time of orientation must be converted into the seat movements by these models, which requires a lot of computing power. And last but not least, these models must be parameterized, e.g. by making assumptions about the influences of friction terms between the seat elements or in the control chain. These models are often either inaccurate (e.g. with linear approximation of the friction effects) or inherently complex and thus difficult to solve. Rotor position-determined orientation estimation of the seat elements therefore inherently causes a (seat structure) parameter identification problem that can only be solved with a high computational effort and often still only inaccurately.

Approach according to this invention: Alternatively, accelerated movements of the sensor can be determined via the yaw rate sensor technology of the reference IMUs. With the help of the yaw rate sensor technology, parts a _mot of the acceleration measurement data that arise from accelerated movement of the seat elements equipped with reference IMUs can be distinguished from the static parts that are caused by the acceleration due to gravity g. By fusing acceleration and yaw rate measurement data, better orientation estimates can be achieved than purely using acceleration measurement data. This effect becomes stronger the worse the approximation ||a _mess ||≈g is (i.e. the greater the external accelerations that act on the IMUs).

The proposal outlined here involves the fusion of the relative rotor position data with absolute measurement data from the IMU acceleration sensor and the IMU angular rate sensor to determine orientation, but at least acceleration and angular rate sensor data. Fusion filter algorithms are to be used for this purpose, hereinafter also simply referred to as filter algorithms.

• Die Filteralgorithmen können je nach geforderter Genauigkeit, vorliegendem Problem (z. B. linear, nichtlinear) und zur Verfügung stehender Rechenkapazität ausgelegt werden. Grundsätzlich lassen sich unter anderem Filtertypen unterscheiden, welche die Systemdynamik zur Orientierungsschätzung nicht explizit modellieren, sondern lediglich auf Basis von Messdaten schätzen, so z. B. Komplementärfilter. Dem stehen Filter mit expliziter Modellierung der Systemdynamik gegenüber, so z. B. Bayessche Filter wie das Kalman-Filter.

The choice of suitable filter algorithms can be done, for example, as follows:

• The filter algorithms can be designed depending on the required accuracy, the problem at hand (e.g. linear, non-linear) and the available computing capacity. In principle, a distinction can be made between filter types that do not explicitly model the system dynamics for orientation estimation, but rather only estimate it on the basis of measurement data, such as complementary filters. In contrast, there are filters that explicitly model the system dynamics, such as Bayesian filters such as the Kalman filter.

Filters with explicit dynamic models have several advantages, such as typically better estimation quality and the ability to make an estimate based on the dynamic model alone in the absence of measurement data. This can be particularly suitable for plausibility checks of rotor position orientation estimates with the orientation estimate based on the IMU data.

A disadvantage is that orientation estimators generally result in non-linear equations of the dynamic model (e.g. through trigonometric terms). Instead of directly modeling the system dynamics and thus the orientation, it is therefore advisable to indirectly model the error process of the orientation estimation, which can lead to a linear system of equations if formulated appropriately.

Example implementations for indirect orientation estimation are already known, see for example Matlab's imufilter (https://de.mathworks.com/help/fusion/ref/imufilter-system-object.html). In this implementation, a Kalman filter is used, which is characterized by low computing power and low memory requirements.

• So sind beispielsweise IMUs als MEMS-Sensoren eine mögliche Ausführungsform, die im Hinblick auf den Bauraum und die Kosten vorteilhaft sein kann, als Komponente verfügbar ist und als Standard im Automotive-Bereich etabliert ist. In einer weiteren Ausführungsvariante können zusätzlich zu den IMU-Sensoren an den Elementen des Objekts (hier beispielhaft Sitz oder Lenksäule) ein weiterer Referenzsensor (Drehratensensor, Beschleunigungssensor oder IMU) für die Messung der auf das Gesamtfahrzeug wirkenden Beschleunigungen a_ext verwendet werden. Damit ist eine weitere Korrektur der Objektposition und -Orientierung möglich.

The basic idea of orientation and position estimation using a redundant IMU absolute sensor and fusion filters can be implemented in different embodiments:

• For example, IMUs as MEMS sensors are a possible embodiment that can be advantageous in terms of installation space and costs, is available as a component and is established as a standard in the automotive sector. In another embodiment, in addition to the IMU sensors on the elements of the object (here, for example, the seat or steering column), another reference sensor (rotation rate sensor, acceleration sensor or IMU) can be used to measure the accelerations a _ext acting on the entire vehicle. This enables further correction of the object position and orientation.

For a design for determining the position and orientation of the seat pan and the backrest of a vehicle seat in the vehicle interior, it would be possible to use the sensor typically present in the airbag or to install a centrally placed reference sensor (cf. 1 ), as well as for determining the position and orientation of a steering column (cf. 2 ).

Short description of the drawings

• 1 eine perspektivische Ansicht eines Innenraums eines Fahrzeugs mit einem motorbasierten Verstell- und Sensor-System gemäß einem Ausführungsbeispiel der Erfindung am Beispiel eines Fahrzeugsitzes;
• 2 dieselbe Ansicht des Innenraums des Fahrzeugs wie in 1 mit einem weiteren motorbasierten Verstell- und Sensor-System gemäß einem Ausführungsbeispiel der Erfindung am Beispiel einer Lenksäule;
• 3 einen vertikalen Längsschnitt eines weiteren motorbasierten Verstell- und Sensor-System gemäß einem Ausführungsbeispiel der Erfindung am Beispiel eines Fahrzeugsitzes; und
• 4 ein Flussdiagramm eines Verfahrens gemäß einem Ausführungsbeispiel der Erfindung zum robusten Ermitteln der Raumlage eines aktorisch verstellbaren Fahrzeuginnenraum-Elements.

The above aspects and their embodiments and specific configurations are explained in more detail below using examples shown in the accompanying drawings. The drawings are to be understood as purely schematic illustrations. Although they can also be understood as being true to scale, this is neither mandatory nor restrictive for the subject matter of the invention. They show:

• 1 a perspective view of an interior of a vehicle with a motor-based adjustment and sensor system according to an embodiment of the invention using the example of a vehicle seat;
• 2 the same view of the interior of the vehicle as in 1 with a further motor-based adjustment and sensor system according to an embodiment of the invention using the example of a steering column;
• 3 a vertical longitudinal section of another motor-based adjustment and sensor system according to an embodiment of the invention using the example of a vehicle seat; and
• 4 a flow chart of a method according to an embodiment of the invention for robustly determining the spatial position of an actuator-adjustable vehicle interior element.

Description of embodiments

All of the various embodiments, variants and specific design features of the method for robustly determining the spatial position of an actuator-adjustable vehicle interior element and the corresponding control unit, the corresponding motor-based adjustment and sensor system and the vehicle equipped therewith according to the aspects of the invention described herein mentioned above in the description and in the following claims can be used analogously in the 1 to 4 shown examples individually or in combinations mentioned herein. They will therefore not all be repeated again below. The same applies accordingly to all definitions and effects already given above in relation to individual features that are included in the 1-4 are shown.

1 shows a perspective view obliquely from above of a section of a vehicle 1, the interior of which is intended for passengers and is indicated by its floor 2, to which the usual vehicle-fixed Cartesian coordinate system (not shown separately) with a vehicle longitudinal direction X, vehicle transverse direction Y and vehicle vertical direction Z is firmly connected. It can be For example, it could be a motor vehicle, in particular a passenger car (car).

• Der Fahrzeugsitz 4 ist am Fahrzeugboden 2 befestigt und relativ dazu als Ganzes verstellbar. Dabei lassen sich seine Bestandteile wie die Sitzwanne oder Sitzfläche 6 und Rückenlehne 7 auch relativ zueinander durch jeweils zugehörige Verstell-Motoren verstellen. Dies ist in 1 am Beispiel einer Lehnen-Neigungsverstellung der Rückenlehne 7 relativ zur Sitzfläche 6 gezeigt und die Verstellbewegung ist durch einen entsprechenden Bewegungspfeil angedeutet.

A steering wheel 3 with an actuator-adjustable steering column 5 (i.e. by an electric adjustment motor, not shown separately) and several actuator-adjustable vehicle seats 4 (the respective adjustment motors are also omitted for illustration reasons) are arranged in the vehicle interior. A motor-based adjustment and sensor system S10 according to an embodiment of the invention is explained below using the example of one of the adjustable vehicle seats 4:

• The vehicle seat 4 is attached to the vehicle floor 2 and is adjustable relative to it as a whole. Its components such as the seat pan or seat surface 6 and backrest 7 can also be adjusted relative to each other by means of the respective adjustment motors. This is shown in 1 using the example of a backrest inclination adjustment of the backrest 7 relative to the seat surface 6 and the adjustment movement is indicated by a corresponding movement arrow.

As already mentioned above, the motor-based adjustment and sensor system S10 in this embodiment comprises, for the purpose of a robust determination of the spatial position (for example the spatial position and orientation with respect to the above vehicle-fixed coordinate system) of the respective vehicle interior element 4, 6 and 7, in addition to the not shown internal drive sensors of the respective adjustment motors, external reference sensors (here purely as an example in the form of an inertial measuring unit, IMU) IMU1 in the seat 6, IMU 2 in the backrest 7 and also IMU3 in the vehicle floor 2 for redundant motor-independent determination of the aforementioned spatial position of the elements 4, 6 and 7.

2 shows the same view of the interior of vehicle 1 as in 1 with a further motor-based adjustment and sensor system S20 according to an embodiment of the invention using the example of the actuator-adjustable steering column 5 of the steering wheel 3. Here, external reference sensors, again each in the form of an inertial measuring unit IMU, for example by using a typically already existing sensor IMU 4 in a steering wheel airbag (not shown separately) and/or by installing a 1 The reference sensor IMU3, which is placed centrally in the vehicle floor 2, is used for redundant, external engine position and orientation determination of the steering column 5.

The method presented here for robustly determining the spatial position of the respective actuator-adjustable vehicle interior element 3, 4, 6, 7 can be carried out, for example, by a control unit 10 provided in the vehicle 1, which is designed and configured to automatically execute this method. For this purpose, a corresponding computer program of the type presented here can be installed in the control unit 10 and run during operation. Purely by way of example, the control unit 10 in this example is housed in the instrument panel 8 of the vehicle 1 and can be implemented, for example, as part of a central control unit of the vehicle 1. Alternatively, it can also be integrated in the respective system S10 or S20, for example in the vehicle seat 4 or the steering column 5, for example as a component of the respective control unit, and can optionally be designed to receive measurement signals from external reference sensors further away.

4 shows a flow chart of a method according to an embodiment of the invention for robustly determining the spatial position of an actuator-adjustable vehicle interior element. This method can, for example, be the above-mentioned method that is carried out by the control unit 10 of the 1 or the 2 Therefore, the following will be purely an example based on the 1 shown adjustable vehicle seat 4.

The method begins with a first step S1, in which, for example, a corresponding start command from a user of the vehicle 1 or an internal vehicle control system is received, for example when starting up all on-board systems when the vehicle 1 is switched on.

In a subsequent step S2, in order to robustly determine the spatial position of the above-mentioned adjustable element (vehicle seat 4 or its seat surface 6 or backrest 7), a first value of its position and/or orientation information required/predetermined for certain control processes in the vehicle 1 relative to the vehicle interior is determined based on an internal drive sensor system of the associated adjustment motor, i.e. motor-related. Using the example of an adjustable vehicle seat 4 or an adjustable steering column 5, this information can be, for example, a one- to three-dimensional information on the spatial position of a predetermined central point and a one- to three-dimensional information on the spatial orientation (angle information) of a predetermined central axis of this element, so that the respective value is determined as a one- to six-dimensional vector in relation to the above-mentioned vehicle-fixed Cartesian coordinate system. Depending on the type of attachment and the adjustment options of the element in relation to the vehicle 1, a higher or, conversely, reduced number of degrees of freedom of movement must be determined, as shown below using the example of a vehicle seat 4 in 3 explained.

In a further step S3, which can also be carried out before or at the same time as step S2, at least one redundant second value of the same position and/or orientation information of the same element is determined based on measurement data from the external reference sensors IMU1, IMU2 and/or IMU3, which are arranged in the vehicle interior without a direct mechanical connection to the adjustment motor (for example outside the adjustment motor on/in the element or even spatially separated from the element) of the element in question. This is therefore a motor-independent determination.

In a control step S4 following steps S2 and S3, the first value is compared with the at least one redundant second value and a deviation between them is determined. This allows the first value to be checked for its integrity or plausibility check. In this example, the determined deviation is compared with a predetermined discrepancy threshold. If it exceeds this threshold (sufficient agreement/plausibility check fails: "no" in step S4), the first value can be corrected using the at least one second value in a correction step S5. The same applies to the algorithm used to determine the first value. After this correction, the method returns to step S2 above and is repeated from step S2.

If, however, a sufficient match is determined in step S4 (“yes”), the method proceeds to step S6, in which the first value of the position and/or orientation information determined in step S2 is used for the vehicle-internal control processes for which it is required. This can include, among other things, a desired active positioning of the element and/or feedback of its current spatial position to other vehicle systems for mutual coordination, etc.

Then, in step S7, it is checked whether the method should not be terminated, for example if there is a shutdown command from the user or an internal vehicle control system, such as when shutting down all on-board systems when switching off the vehicle 1. If this is the case (“yes”), the method is terminated with the corresponding step S8. Otherwise (“no”), the method is continued cyclically from step S2.

3 shows in a vertical longitudinal section a section of a vehicle 1, the interior of which is intended for passengers and is similar to 1 and 2 is indicated by its base 2. The 3 The usual vehicle-fixed Cartesian coordinate system K1, also shown, with a vehicle longitudinal direction X1, vehicle transverse direction Y1 and vehicle vertical direction Z1 is fixed with respect to the vehicle interior and the vehicle floor 2. This can also be a motor vehicle, in particular a passenger car (car).

A vehicle seat 4 for an occupant (not shown), for example a driver of the vehicle 1, is arranged in the vehicle interior. Further elements that can be provided in the interior of the vehicle 1 are shown in 1 omitted for the sake of a clear representation. For the vehicle seat 4, a Cartesian coordinate system K _{IMU2 is also shown, which is firmly connected to its backrest 7, ie the seat's own Cartesian coordinate system K IMU2} with a longitudinal direction X _IMU2 , transverse direction Y _IMU2 and backrest vertical direction Z _IMU2 .

• In einer weiteren Ausführungsform kann die Positions- und Orientierungsbestimmung der Sitzelemente 6 und 7 (bzw. der Lenksäule 5 der 2) durch Referenz-IMUs mit einer reduzierten Anzahl von Freiheitsgraden bestimmt werden: Im allgemeinen Fall sind für eine vollständige Positions- und Orientierungsbestimmung je drei Koordinaten(achsen) zur Messung der Beschleunigung in der Richtung dieser Achsen sowie für Messung der Drehraten um diese Achsen ausreichend. Damit ergibt sich ein Sensorsystem mit sechs Freiheitsgraden. Bei geschickter Platzierung hingegen kann man mit weniger Freiheitsgraden auskommen. Das ist in 3 beispielhaft für eine Positions- und Orientierungsbestimmung der Sitzelemente 6 und 7 veranschaulicht:
  • Wenn der Sitz 4 und der Referenzsensor IMU3 (siehe 1 und 2) in einem Fahrzeugzentrum des Bodens 2 mechanisch fix und verwindungssteif verbunden sind, so sind y-Achse Y1 des Fahrzeugs und y-Achsen Y_IMU1 (nicht extra dargestellt) und Y_IMU2 der sitzgebundenen Referenzsensoren IMU1 und IMU2 an den Sitzelementen 6 und 7 stets achsparallel. Damit muss lediglich der zentrale Referenzsensor IMU3 (s. 1 und 2) über sechs Freiheitsgrade verfügen, die beiden sitzfesten Referenzsensoren IMU1 und IMU2 an den Sitzelementen 6 und 7 können Position und Orientierung dieer Sitzelemente auch mit nur je drei Freiheitsgraden bestimmen, nämlich die Beschleunigung in Richtung der x- und z-Achse sowie die Drehrate um die y-Achse des jeweiligen Referenzsensors). Solche IMUs mit nur drei Freiheitsgraden sind in der Regel kleiner und/oder preiswerter als IMUs, die zur Ermittlung von allen sechs Freiheitsgrade ausgelegt sind.

The vehicle seat 4 is attached to the vehicle floor 2 and is adjustable relative to it as a whole. Furthermore, its seat surface 6 and backrest 7 are adjustable relative to each other. In addition, reference is made at this point to a consistent description with regard to the vehicle seat 4 in 1 so that only the following addition is described below:

• In a further embodiment, the position and orientation determination of the seat elements 6 and 7 (or the steering column 5 of the 2 ) are determined by reference IMUs with a reduced number of degrees of freedom: In general, three coordinates (axes) are sufficient for a complete position and orientation determination to measure the acceleration in the direction of these axes and to measure the rotation rates around these axes. This results in a sensor system with six degrees of freedom. With clever placement, however, fewer degrees of freedom can be used. This is in 3 An example of a position and orientation determination of the seat elements 6 and 7 is illustrated:
  • If the seat 4 and the reference sensor IMU3 (see 1 and 2 ) are mechanically fixed and torsionally rigidly connected in a vehicle center of the floor 2, the y-axis Y1 of the vehicle and the y-axes Y _IMU1 (not shown separately) and Y _IMU2 of the seat-based reference sensors IMU1 and IMU2 on the seat elements 6 and 7 are always axially parallel. This means that only the central reference sensor IMU3 (see 1 and 2 ) have six degrees of freedom, the two seat-mounted reference sensors IMU1 and IMU2 on the seat elements 6 and 7 can also determine the position and orientation of these seat elements with only three degrees of freedom each, namely the acceleration in the direction of the x and z axes and the rotation rate around the y axis of the respective reference sensor). Such IMUs with only three degrees of freedom are usually smaller and/or cheaper than IMUs that are designed to determine all six degrees of freedom.

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed 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 accepts no liability for any errors or omissions.

Cited patent literature

• WO 2014/197312 A1 [0004]

Claims (12)

Method for robustly determining the spatial position of a vehicle interior element (4, 5, 6, 7) that is adjustable by an electric adjustment motor, comprising the steps: - motor-related determination of a first value of a predetermined position and/or orientation specification of the element (4, 5, 6, 7) relative to the vehicle interior based on a drive-internal sensor system of the adjustment motor (S2); - redundant motor-independent determination of at least one second value of the same position and/or orientation specification of the element (4, 5, 6, 7) based on measurement data from at least one external reference sensor (IMU1-IMU4) that is arranged in the vehicle interior without a direct mechanical connection to the adjustment motor (S3); - comparing the motor-related determined first value with the motor-independently determined at least one second value and determining a deviation therebetween (S4); - Plausibility check and/or correction of the first value and/or its engine-related determination algorithm depending on the determined deviation (S5), before it is subsequently used for predetermined control processes in the vehicle interior (S6). Procedure according to Claim 1 , wherein - the drive-internal sensor system of the adjustment motor is designed as a rotor position sensor system which directly measures a rotation rate and/or a rotation angle and/or a torque of a rotor shaft of the adjustment motor or determines it from a direct measurement of another rotor position measurement variable; and - the first value of the said position and/or orientation information of the element (4, 5, 6, 7) is determined therefrom by the associated motor-related determination algorithm (S2). Procedure according to Claim 1 or 2 , wherein - the reference sensor (IMU1, IMU2, IMU3, IMU4) or at least one of the plurality of reference sensors (IMU1-IMU4) is designed as an inertial sensor, in particular as an inertial measuring unit. Method according to one of the preceding claims, wherein - a correction (S5) of the first value and/or its engine-related determination algorithm is carried out using the at least one engine-independently determined second value only if the determined deviation exceeds a predetermined discrepancy threshold value. Method according to one of the preceding claims, wherein - the at least one second value and/or the first value is determined by applying a predetermined (fusion) filter algorithm to the measurement data of the at least one external reference sensor and/or the internal drive sensor system of the adjustment motor. Procedure according to Claim 5 , wherein - said (fusion) filter algorithm estimates the orientation of the element (4, 5, 6, 7) to be determined on the basis of measurement data without an explicit modeling of the respective system dynamics, such as when applying a complementary filter; and/or - said (fusion) filter algorithm estimates the orientation of the element (4, 5, 6, 7) to be determined on the basis of measurement data using an explicit dynamics model of the respective system, such as when applying a Bayesian filter, in particular a Kalman filter. Method according to one of the preceding claims, wherein the at least one external reference sensor (IMU1, IMU2, IMU3, IMU4) comprises: - at least one reference sensor (IMU1, IMU2, IMU4) permanently connected to the element, in particular one reference sensor (IMU1, IMU2) in or on several independently adjustable components (6, 7) of the element (4); and/or - at least one reference sensor (IMU3) fastened in the vehicle interior without a direct mechanical connection to the element (4, 5, 6, 7). Control unit (10) comprising a processor configured to carry out a method according to any one of the preceding claims. Computer program comprising instructions which, when the computer program is executed in a control unit (10) or a computer, cause the latter to carry out a method according to one of the Claims 1 until 7 to execute. Machine-readable storage medium on which a computer program according to Claim 9 is stored. Motor-based adjustment and sensor system (S10, S20) for a vehicle (1), comprising: - at least one adjustable vehicle interior element (4, 5, 6, 7); - for one or more independent translation and/or rotation axes of each of these elements (4, 5, 6, 7), an associated electric adjustment motor, wherein the respective motor comprises a drive-internal sensor system, on the basis of which a first value of a predetermined position and/or orientation Specification of the element (4, 5, 6, 7) relative to the vehicle interior; and - a control unit (10) according to Claim 8 , which are used to carry out a process according to one of the Claims 1 until 7 trained and equipped for each of these engines. Vehicle (1), in particular a motor vehicle, with a motor-based adjustment and sensor system (S10, S20) according to Claim 11 .

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