Stability system and procedures for an active chassis of a motor vehicle

Abstract

A stability system for an active chassis of a motor vehicle is provided, comprising a wheel sensor (22) for detecting the acceleration of a wheel system of a wheel suspension, a body sensor (20) for detecting the acceleration of a body of the motor vehicle connected to the wheel system via a shock absorber, wherein the wheel sensor (22) and the body sensor (20) are identically designed and identically programmed acceleration sensors, and a control unit (24) for reading sensor data from the wheel sensor (22) and the body sensor (20) via a predefined data bus protocol, in which the transmission of sensor data from different sensors (20, 22) is provided in time-spaced time slots (12, 14, 16, 18), wherein the control unit (24) is configured to first assign a first time slot (12) to the body sensor (20) and a second time slot (14) different from the first time slot (12) to the wheel sensor (22).before the control unit (24) reads the sensor data from the wheel sensor (22) and the body sensor (20). This enables fast and cost-effective sensor technology for a stability system of an active chassis of a motor vehicle.

Description

[0001] The invention relates to a stability system by which an active suspension of a motor vehicle can be stabilized, and to a motor vehicle with such a stability system. Furthermore, the invention relates to a method by which a stability system for an active suspension of a motor vehicle can be operated.

[0002] It is known to use different acceleration sensors for an active chassis as wheel sensors and body sensors, which are pre-configured for different time slots for sending sensor data and have different shape codes so that the wheel sensor and the body sensor cannot be confused during assembly.

[0003] DE 10 2009 002 708 A1 shows a control unit of a motor vehicle which controls various identical sensors via a PSI5 bus, wherein the control unit evaluates sensor data transmitted in a first time slot based on a known driving situation and plausibly verifies the data based on the known driving situation in order to identify the respective sensor, and subsequently assigns different time slots, different from the first time slot, to each of the identified sensors for sending their sensor data.

[0004] DE 199 45 614 C1 discloses a control system with which several airbags of a motor vehicle can be triggered depending on data from different acceleration sensors, wherein the data of the acceleration sensors, which are identifiable via a unique address, are queried by means of a request telegram of the control system, wherein the request telegram specifies whether and in which time slot the respective acceleration sensor should send data.

[0005] There is a constant need to design the sensor technology for a stability system for an active chassis of a motor vehicle as quickly and cost-effectively as possible.

[0006] The object of the invention is to demonstrate measures that enable fast and cost-effective sensor technology for a stability system of an active chassis of a motor vehicle.

[0007] The problem is solved according to the invention by a stability system with the features of claim 1, a motor vehicle with the features of claim 5, and a method with the features of claim 7. Preferred embodiments of the invention are specified in the dependent claims and the following description, each of which can individually or in combination represent an aspect of the invention, the scope of protection being determined by the claims.

[0008] One aspect of the invention relates to a stability system for an active chassis of a motor vehicle, comprising a wheel sensor for detecting an acceleration of a wheel system of a wheel suspension, a body sensor for detecting an acceleration of a body of the motor vehicle connected to the wheel system via a shock absorber, wherein the wheel sensor and the body sensor are identically designed and identically programmed acceleration sensors, a control unit for reading sensor data from the wheel sensor and the body sensor via a predefined data bus protocol, in particular PSI5, in which the transmission of sensor data from different sensors is provided in time-spaced time slots, wherein the control unit is configured to first assign a first time slot to the body sensor and a second time slot different from the first time slot to the wheel sensor.before the control unit reads the sensor data from the wheel sensor and the body sensor.

[0009] It was discovered that, in the case of the active suspension's wheel sensor and body sensor, it is not actually necessary to pre-configure them for transmitting sensor data in different time slots at the factory. Instead of purely unidirectional communication between the wheel sensor and body sensor on the one hand, and the control unit on the other, it is possible to implement bidirectional communication, at least temporarily, between the wheel sensor and body sensor as transmitters and the control unit as receivers. In this bidirectional communication, the control unit, as the transmitter, first specifies the different time slots for transmitting the sensor data to the wheel sensor and / or the body sensor as receivers. This allows the wheel sensor and body sensor to be designed as identical parts with the same shape, identical functionality, and identical part numbers for warehousing and logistics.Increasing the number of identical parts within a common vehicle makes it easy to reduce manufacturing costs, particularly through mass production methods. Furthermore, assembly is simplified, as there is no need to differentiate between the wheel sensor and the body-mounted accelerometer at the time of assembly.

[0010] This method utilizes the fact that it is possible to distinguish between the wheel sensor and the body sensor, even when installed, based on their location. The differentiation between the wheel sensor and the body sensor is not achieved through the evaluation and plausibility check of the sensor data. Instead, it is possible to exploit the relative spatial position of the installation locations of the wheel sensor and the body sensor for their respective identification and / or differentiation.The different installation locations can lead to different physical effects within otherwise identical sensors, for example, due to a different relative orientation of the sensors to the direction of gravity. This physical effect can be derived from the sensor measurement data and used by the control unit to identify the respective sensor as a wheel sensor or body sensor, without requiring the acquisition and evaluation of measurement data, especially acceleration data, during driving or the addition of an individual code to the measurement data for identification. With a defined chassis topology, it is already clear at the delivery state of the control unit which sensor is connected to which installation location and which physical effects influence the measurement signal of the respective sensor.Due to the spatial separation between the wheel sensor on the wheel system and the body sensor, which is located, in particular, on the shock absorber strut, it can be reliably ruled out that identical physical effects act on the wheel sensor and the body sensor. Therefore, it is fundamentally possible, based on the geometrically defined topology of the chassis's design, the resulting sensor installation locations, and the prevailing physical conditions, to reliably distinguish the wheel sensor from the body sensor within the control unit. This ensures that the control unit can unambiguously determine which sensor data originates from which sensor.Due to the different physical conditions at the various installation locations, the control unit can identify the wheel sensor and the body sensor and respond to them at different time slots, thus enabling fast and cost-effective sensor technology for a stability system of an active chassis of a motor vehicle.

[0011] The stability system can, for example, adjust the spring rate and / or the spring travel of the active suspension's shock absorbers to ensure that the vehicle body and its occupants move as smoothly as possible.

[0012] The wheel system can comprise a wheel carrier and a wheel connected to the wheel carrier, the wheel comprising a rim connected to the wheel carrier and a tire mounted on the rim. Road surface irregularities can be transmitted as vibrations to the wheel system of the suspension via the tire of the wheel system and dampened before being transferred to the vehicle body via the shock absorber of the active suspension.

[0013] The control unit can read sensor data and thereby determine the current movement of the vehicle's wheels and body. Using the data collected by the control unit, the stability system can be controlled, particularly to improve the vehicle's driving dynamics and / or safety.

[0014] The wheel sensor can, in particular, measure the movement of a corresponding wheel and / or the acceleration forces acting on the wheel. With the help of the wheel sensor, for example, the condition of a surface can be detected.

[0015] The body-on-frame sensor can, in particular, measure the movement of the vehicle body and / or the acceleration forces acting on the body and its occupants. Specifically, the sensor data from the body-on-frame sensor represents a control variable to be optimized within the stability system. The body-on-frame acceleration sensor can be directly or indirectly coupled to a strut mount, to which the strut is connected via a strut bearing to the body, with the strut being supported on the wheel suspension system by a spring and / or a damper.

[0016] The data bus protocol corresponds in particular to PSI5 or a similar protocol, in which time-shifted time slots are reserved for reading sensors at a reference time. These time slots do not overlap, so that after time synchronization, the respective sensors send their sensor data at different time slots in each transmission cycle. The time of each time slot within the respective transmission cycle can be assigned to a defined sensor via appropriate coding, so that the control unit can precisely distinguish which sensor is sending which sensor data.

[0017] The time slot is a time-limited period within a transmission cycle, which can be defined by the data bus protocol. In particular, the data bus protocol specifies a precisely predefined time slot length, whereby it is generally possible to provide different time slots for different sensors or to use the same time slot for all sensors.

[0018] In particular, the control unit is designed to differentiate between the wheel speed sensor and the body-mounted sensor by detecting various measurable physical effects at their respective installation locations. These physical effects can manifest in the measurement signals of the sensors installed at their different locations and be evaluated by the control unit, especially when the vehicle is at rest. For example, it can be used to exploit the fact that the measurement signal of each sensor can produce a different amplitude reading for a non-oscillating zero state, depending on its specific installation position.

[0019] Preferably, the wheel sensor and the body sensor are positioned at spatially different locations within the chassis topology when installed. The control unit is designed to distinguish the wheel sensor from the body sensor based on these different positions within the chassis topology. For example, the control unit can be configured to recognize the location within the chassis topology of each sensor, which is considered a common component, and / or the location within the chassis topology from which the sensor data of the common component originates. For this purpose, prevailing physical effects at the different sensor installation locations can be detected. This allows the wheel sensor to be distinguished from the body sensor very quickly, despite identical sensor designs, and assigned to the correct time slot.

[0020] Preferably, the wheel sensor and the body sensor are pre-configured in their delivery state to transmit in the same preset timeslot within the predefined data bus protocol, whereby the control unit is designed to cause either only the wheel sensor or only the body sensor to transmit in a timeslot different from the preset timeslot. The sensors intended as sliding parts can be programmed identically in their delivery state, which would cause both sensors to transmit in the same predefined timeslot. In this case, it may be sufficient for the control unit to reprogram only one of the sensors, i.e., either the wheel sensor or the body sensor, to a different timeslot, for example, by assigning a different value to a timeslot-defining variable within the sensor in question.After this allocation of the other time slot, simultaneous transmission of the two sensors, which are installed as identical parts with originally identical programming, is avoided.

[0021] Another aspect concerns a motor vehicle with an active suspension system comprising at least one wheel suspension and a stability system that can be configured and further developed as described above. Due to the different physical conditions at the various installation locations, the control unit can identify the wheel sensor and the body sensor and respond to them at different time slots, thus enabling fast and cost-effective sensor technology for the stability system of a motor vehicle's active suspension.

[0022] In particular, multiple wheel suspensions, for example four independent wheel suspensions, each with a body sensor and a wheel sensor, are provided, whereby different time slots are assigned to the sum of all body and wheel sensor readings, and the sum of all body and wheel sensor readings communicates with exactly one control unit. This allows a single control unit to read the sensors of different wheel suspensions sequentially within a common and correspondingly long transmission cycle and use the data for control in the stability system for the active suspension.

[0023] Another aspect of the invention relates to a method for operating a stability system for an active chassis of a motor vehicle, in which a wheel sensor is provided for detecting an acceleration of a wheel system of a wheel suspension and a body sensor is provided for detecting an acceleration of a body of the motor vehicle connected to the wheel system via a shock absorber, wherein the wheel sensor and the body sensor are identically designed and identically programmed acceleration sensors, wherein a control unit for operating the stability system distinguishes the wheel sensor from the body sensor based on a spatially different positioning of the wheel sensor and the body sensor, wherein in a start-up phase the control unit specifies a time slot for a predefined data bus protocol to the wheel sensor and / or the body sensor.In particular, the wheel sensor and the body sensor communicate with the control unit via the data bus protocol in different time slots, and in an operating phase following the start-up phase, the body sensor sends sensor data to the control unit via a predefined data bus protocol in a first time slot and the wheel sensor in a second time slot different from the first. Preferably, the stability system is designed and further developed as described above. Due to the different physical conditions at the various installation locations, the control unit can identify the wheel sensor and the body sensor and respond to them in different time slots, thus enabling fast and cost-effective sensor technology for a stability system of an active chassis of a motor vehicle.

[0024] It is particularly preferred that the control unit transmits data to the body sensor and / or the wheel sensor only during the start-up phase and receives sensor data unidirectionally only during the operating phase. During the start-up phase, when the vehicle has typically not yet started moving, the control unit can perform actions relevant to the operation of the stability system, in particular specifying different time slots for the wheel sensor and the body sensor. During the operating phase, when the vehicle is moving, such organizational actions are no longer necessary, and the control unit can operate in a time-optimized mode that processes the sensor data and achieves convenient and safe chassis control of the active suspension.

[0025] The start phase begins specifically after a cold start of the vehicle. Preferably, a start phase is not performed during a warm start, particularly in vehicles with a start-stop system. Instead, the control unit and sensors can continue to be supplied with electrical energy by the vehicle battery when the vehicle is switched off with a warm engine, ensuring that the time slots allocated to the sensors are not lost and are still available for a subsequent warm start. If the vehicle has been stationary for such a long time after being switched off that a cold start with a restart of the data bus system is required for a restart, the start phase is performed as a precaution to prevent data errors.

[0026] The invention is now explained by way of example with reference to the accompanying drawings and preferred embodiments, wherein the features shown below can represent an aspect of the invention, either individually or in combination, and the scope of protection is defined by the claims. The drawings show: Fig. 1: a schematic diagram of a transmission cycle of the method according to the invention, Fig. 2: a schematic representation of a first embodiment of the method according to the invention and Fig. 2: a schematic representation of a second embodiment of the method according to the invention.

[0027] As in Fig. As shown in Figure 1, a transmission cycle T for transmitting sensor data from various sensors of an active chassis of a motor vehicle can be defined by time between two voltage pulses 10. Each voltage pulse 10 can be initiated by a control unit 24 on an electrical line to specify a clocking sequence for the respective transmission cycles T and to provide a reference signal to which various time-shifted and non-overlapping time slots 12, 14, 16, 18 are oriented. The time slots 12, 14, 16, 18 within the transmission cycle T can conform to a predefined data bus protocol, in particular PSI5.For example, a first timeslot 12 can be designated for transmitting sensor data from a body sensor 20 of a first wheel suspension of an active chassis, and a second timeslot 14 for transmitting sensor data from a wheel sensor 22 of the first wheel suspension, while a third timeslot 16 and a fourth timeslot 18 can be used for transmitting sensor data from other sensors. The body sensor 20 and the wheel sensor 22 can be installed as identical components, particularly with identical programming, so that in their original installed state, the body sensor 20 and the wheel sensor 22 should actually transmit in the same timeslots 12, 14, 16, 18.

[0028] As in Fig. As shown in Figure 2, however, in a start-up phase 26, particularly during a cold start of the vehicle with a restart of the data bus system, the control unit 24 can initially send a signal to the body sensor 20 and the wheel sensor 22 in order to intervene in the pre-installed programming of the body sensor 20 and the wheel sensor 22 so that in an operating phase 28 following the start-up phase 26, the body sensor 20 transmits in the first time slot 12 and the wheel sensor 22 in the second time slot 14. This utilizes the fact that the control unit 24 can distinguish between the body sensor 20 and the wheel sensor 22 due to their significantly different positions within the wheel suspension.

[0029] As in Fig.As shown in Figure 3, it is possible that at least one of the identically programmed and identically installed sensors 20, 22, for example the body sensor 20, is already configured for the correct time slot 12, 14, 16, 18 by its original programming. In this case, it is sufficient if the control unit 24 only reprograms the other sensor 22, 20, here the wheel sensor 22, to a different time slot 12, 14, 16, 18 during the start-up phase.

Claims

[1] Stability system for an active chassis of a motor vehicle, comprising a wheel sensor (22) for detecting an acceleration of a wheel system of a wheel suspension, a body sensor (20) for detecting an acceleration of a body of the motor vehicle connected to the wheel system via a shock absorber, wherein the wheel sensor (22) and the body sensor (20) are identically designed and identically programmed acceleration sensors, a control unit (24) for reading sensor data from the wheel sensor (22) and the body sensor (20) via a predefined data bus protocol, in which the transmission of sensor data from different sensors (20, 22) is provided in time-spaced time slots (12, 14), wherein the control unit (24) is designed to first assign a first time slot (12) to the body sensor (20) and a second time slot (14) to the wheel sensor (22) that is different from the first time slot (12), before the control unit (24) reads the sensor data from the wheel sensor (22) and the body sensor (20). [2] Stability system according to claim 1, wherein the control unit (24) is designed to distinguish the wheel sensor (22) from the body sensor (20) by means of various measurable physical effects at the installation locations of the wheel sensor (22) and the body sensor (20). [3] Stability system according to claim 1 or 2, wherein the wheel sensor (22) and the body sensor (20) are positioned at spatially different positions within a topology of the chassis when installed, wherein the control unit (24) is configured to distinguish the wheel sensor (22) from the body sensor (20) via the different positions within the topology of the chassis. [4] Stability system according to one of claims 1 to 3, wherein the wheel sensor (22) and the body sensor (20) are preset in a delivery state to transmit in the same preset time slot (12, 14) within the predefined data bus protocol, wherein the control unit (24) is configured to cause either only the wheel sensor (22) or only the body sensor (20) to transmit in a time slot (12, 14) different from the preset time slot (12, 14). [5] Motor vehicle comprising an active chassis having at least one wheel suspension and a stability system according to any one of claims 1 to 4. [6] Motor vehicle according to claim 5, wherein several wheel suspensions are provided, each with a body sensor (20) and a wheel sensor (22), wherein different time slots (12, 14) are assigned to the sum of all body sensors (20) and wheel sensors (22) and the sum of all body sensors (20) and wheel sensors (22) communicate with the exactly one control unit (24). [7] Method for operating a stability system for an active chassis of a motor vehicle, wherein a wheel sensor (22) for detecting an acceleration of a wheel system of a wheel suspension and a body sensor (20) is provided for detecting an acceleration of a body of the motor vehicle connected to the wheel system via a shock absorber, wherein the wheel sensor (22) and the body sensor (20) are identically designed and identically programmed acceleration sensors, wherein a control unit (24) for operating the stability system distinguishes the wheel sensor (22) from the body sensor (20) on the basis of a spatially different positioning of the wheel sensor (22) and the body sensor (20), wherein in a start phase (26) the control unit (24) specifies a time slot (12, 14) for a predefined data bus protocol to the wheel sensor (22) and / or the body sensor (20) and In one of the operating phases (28) following the start phase (26), the body sensor (20) in a first time slot (12) and the wheel sensor (22) in a second time slot (14) different from the first time slot (12) send sensor data to the control unit (24) via a predefined data bus protocol. [8] Method according to claim 7, wherein the stability system is configured according to any one of claims 1 to 4. [9] Method according to claim 7 or 8, wherein the control unit (24) only sends to the body sensor (20) and / or the wheel sensor (22) during the start-up phase (26) and only receives the sensor data unidirectionally during the operating phase (28). [10] Method according to one of claims 7 to 9, wherein the start-up phase after a cold start of the motor vehicle begins with a restart of a data bus system.

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