Detecting a wading movement of a vehicle

Abstract

Method for detecting wading of a vehicle (1), wherein during wading a floating movement of the vehicle (1) occurs due to a vehicle-specific wading depth, wherein the vehicle (1) comprises a chassis with a first axle (12) and a second axle (13), wherein at least one first height sensor (7) is provided which is assigned to the first axle (12), wherein at least one second height sensor (8) is provided which is assigned to the second axle (13), wherein height fluctuations of the body of the vehicle (1) can be detected with the height sensors (7, 8) and wherein a decision is made on the basis of sensor values ​​of the height sensors (7, 8) as to whether wading has occurred.

Description

[0001] The invention relates to methods and devices for detecting wading of a vehicle.

[0002] When land vehicles drive or wade through large accumulations of water, for example when crossing a ford or when paths or roads are flooded, it is essential that a specified wading depth is not exceeded, up to which the vehicle can operate as intended.

[0003] Publication WO 2012 / 080429 A1 discloses a method and a sensor device in which a surface driven on by a vehicle is scanned using suitable measurement technology to determine the water depth through which the vehicle is wading. Suitable measurement technologies for such a sensor include cameras and sensors that detect water using reflection or transmission of a waveform. Geographic data sensors, including GPS sensors, are also mentioned.

[0004] Publication WO 2012 / 080430 A1 describes corresponding methods and sensor devices in which the surface being driven on by a vehicle is scanned to determine the water depth through which the vehicle is wading. Suitable measurement techniques for such a sensor include capacitive measurement or resistance measurement using electrodes, as well as ultrasonic measurement technology.

[0005] The publication WO 2012 / 080432 A1 describes a hydrostatic pressure sensor which is used to determine the corresponding water depth under a wading vehicle.

[0006] Publication GB 2 356 602 B describes a measuring system for a vehicle in which a water bow wave created in front of the vehicle during fording is detected using a radar or sonar device. The height of the bow wave can be recorded.

[0007] US 2010 / 0 112 387 A1 discloses monitoring a fuel cell-powered vehicle to prevent uncontrolled water from entering the fuel cell system. For this purpose, sensors are provided on the vehicle, such as a camera that monitors the area around a wheel or flow sensors for liquids. It may also be possible to measure the water level on the road.

[0008] GB 2 504 932 A also describes a system for measuring the water level on a vehicle. This system uses two sets of sensors. The first set includes a LIDAR (Light Detection and Ranging) sensor located in the front of the vehicle. The second set includes several groups of float switches, which are arranged, for example, along a wheel arch or at the rear of the vehicle.

[0009] GB 2 487 112 A describes a system in which several sensors are arranged in a vehicle to measure the water level during a fording journey of a vehicle and to provide the driver with information and instructions on how to drive the vehicle.

[0010] From DE 10 2013 222 022 A1 it is known to use the vehicle's distance sensors to detect when it has passed through water.

[0011] From DE 10 2012 015 764 A1 a flood detection system for motor vehicles is known in which a distance sensor is provided above the vehicle floor, which is intended to detect a distance to a water surface on the ground. In the document

[0012] https: / / de.wikipedia.org / w / index.php?title=Gel%C3%A4ndewagen&oldid=130054496 (version from 03.05.2014) describes various characteristics of off-road vehicles, including aspects that may be relevant in connection with the fording depth. In the document

[0013] https: / / de.wikipedia.org / w / index.php?title=Wattiefe&oldid=122330722 (version from 08.09. 2013) various aspects are described that can be relevant for a wading depth, for example when wading through bodies of water.

[0014] The object of the invention is to reliably detect a wading movement of a vehicle.

[0015] This object is achieved by the invention defined in the independent patent claims. Advantageous embodiments of the invention are defined in the dependent claims.

[0016] According to a first aspect of the invention, to detect wading of a vehicle comprising a chassis with a first axle and a second axle, at least one first ride height sensor is provided, which is assigned to the first axle, and at least one second ride height sensor is provided, which is assigned to the second axle. The ride height sensor can detect fluctuations in the height of the vehicle's body. Based on sensor values ​​from the ride height sensors, a decision is made as to whether wading is occurring.

[0017] This aspect of the invention is based on the finding that, when wading, a certain vehicle-specific wading depth is reached, the vehicle will float upwards, which becomes more pronounced with increasing water depth. This aspect of the invention further recognizes that such a float upward movement can be detected by a corresponding vehicle level sensor, at least until the wading depth is reached.

[0018] In particular, it was recognized that a wading condition can be detected by the floating movement of the vehicle, since under such conditions a rebound movement occurs on both the front axle and the rear axle of the vehicle and this situation differs from normal driving situations, i.e. from situations without wading. The vehicle floats due to the buoyancy effect. The invention can be used in particular to detect the deflection of chassis elements such as the rebound travel of springs or shock absorbers. The respective deflection or rebound movement is measured in particular using sensors in the chassis and detected by an evaluation unit. The sensors are preferably located on the wishbones of the chassis, are designed in particular as potentiometers and can be deflected via bellcranks.Alternative sensor systems can, for example, be located directly on the shock absorbers and, as travel sensors, directly detect the rebound movement and, if necessary, measure the rebound stroke. For this purpose, corresponding sensors and their measurement signals can advantageously be used twice, for example, additionally for other control tasks such as headlight range adjustment in a low-beam control system. With the invention, the vehicle can essentially be used as a float, with signal processing being carried out analogously to known float measurement systems.

[0019] Within the scope of the first aspect of the invention, a measuring device for detecting wading of a vehicle comprising a chassis with at least one ride height sensor can also be specified. A decision as to whether wading is occurring can be made based on sensor values ​​from the ride height sensor. The measuring device, in particular, has a device for processing the sensor values. It can further comprise one or more means for carrying out the method steps described here. The invention can also be used to specify a correspondingly equipped vehicle, in particular a motor vehicle.

[0020] In an advantageous embodiment of the invention, at least one corresponding ride height sensor is provided for each axle, in particular on the front axle, and for each axle, in particular on the rear axle. This advantageously allows a longitudinal inclination of the vehicle to be measured. Furthermore, at least two ride height sensors can be provided, in particular on each axle. This advantageously allows a lateral inclination of the vehicle to be measured. The ride height sensors can each be provided, in particular, in the area of ​​the vehicle's suspension spring and / or damping elements. In particular, they can be firmly connected to these elements.

[0021] Advantageously, a plurality of ride height sensors can also be provided for at least one of the axles so that different ride height changes can be detected along the axle. In particular, a plurality of ride height sensors can be provided for the front axle and / or the rear axle so that ride height fluctuations caused by cornering and / or acceleration can be detected and distinguished from ride height fluctuations caused by fording. If, therefore, at least two corresponding sensors are advantageously provided per vehicle axle, it can be achieved that a floating movement of the vehicle can be clearly distinguished from a cornering movement of the vehicle. This is because during a floating movement the ride height changes along an axis (left or right) are directed upwards or downwards in the same way, whereas during a cornering movement they are directed in the opposite direction.The same applies to distinguishing between a ride height change on the front axle of the vehicle caused by a floating movement and a pitching movement of the vehicle caused by acceleration. In the case of a floating movement, the ride height changes on the front and rear axles are in the same direction, namely upwards, whereas in the case of a pitching movement they are opposite to each other. Accordingly, when the vehicle accelerates, a vertical movement or ride height change occurs on the front axle and a vertical movement downwards on the rear axle, whereas when braking, exactly the opposite vertical movements occur. These effects can be advantageously used within the scope of the invention when evaluating the measurement signals from the respective ride height sensors in order to distinguish between the respective vehicle movements as reliably as possible.

[0022] In further advantageous embodiments of the invention, it can also be provided that measured values ​​are recorded for the respective water depth, because even with sufficient fording capability or fording depth, crossing water bodies such as bodies of water or flooded areas is inherently risky for a land vehicle. Various hazards can arise both in open terrain and at designated fords and on flooded paths: - The maximum water depth to be crossed is usually neither precisely known nor precisely determined. - The condition of the ground is unknown or rarely accurately assessable. This may cause the vehicle to sink. - Undetected obstacles, debris and uneven ground can lead to collisions and getting stuck. - A water current, even at low speed and in shallow water, can sweep the vehicle away and / or place it in an area where it is no longer maneuverable and / or where its wading depth is exceeded, causing the vehicle to become unstable or its propulsion to fail, for example. - The lift reduces the grip on the road and thus the traction of the vehicle. - The higher the speed, the greater the effect of the buoyancy movement and the higher the bow wave and the greater the risk of water hammer.

[0023] At least some of the measured values ​​for determining the water depth can advantageously be recorded using the at least one height sensor. To detect the wading activity and / or the respective water depth, signals from at least one mechanical, electrical, optical, and / or other component, such as an ultrasonic component, a radar component, or a sonar component, are used.

[0024] The invention can advantageously detect even a relatively low water level and, particularly at higher water levels, prevent water hammer in the motor.

[0025] The methods described above for detecting wading and / or for determining the water depth beneath and / or beside the vehicle can be supplemented by further measures and thus further improved in terms of their detection accuracy. For example, to detect wading of the vehicle, it can additionally be provided to make a decision as to whether wading has occurred on the basis of sensor values ​​that represent an electrical quantity. The electrical quantity can in particular be an electrical resistance. However, it can also be another quantity such as a dielectric constant. The electrical quantity can in particular be measured and / or evaluated in analog form. The sensor values, in particular analogue values, can represent an electrical quantity in the area of ​​and / or on a radiator surface of the vehicle. The sensor can for example be designed as a resistance sensor or as a capacitance sensor.The electrical variable can be recorded directly at the radiator surface and, in particular, can be a variable of the radiator surface itself. A sensor for generating corresponding sensor values ​​can also be arranged on each of a plurality of radiator surfaces and / or coolers provided in the vehicle, in particular those arranged close to one another and each electrically insulated from one another. The coolers and / or cooler surfaces can also be part of the sensor as such, and the sensor can be designed, in particular, as a resistance sensor and / or as a capacitive sensor. The coolers or cooler surfaces can each interact to generate the sensor values. For this purpose, they can, in particular, be arranged close to one another and / or be electrically insulated from one another.To generate the sensor values, a first cooler surface of a first cooler can form a first electrode of the sensor, and a second cooler surface of a second cooler, which is electrically insulated from the first cooler surface, can form a second electrode of the sensor. The first cooler can be an engine water cooler, and the second cooler an air conditioning condenser. Further details on these method measures and measuring device components are described in the German patent application filed in parallel by the applicant with the internal file number 25860-2, the content of which is hereby incorporated by reference into the present patent application.

[0026] A camera can also be used for water detection. A light barrier can also be used to detect the height of the chassis and / or the water level. Furthermore, a pressure increase in the intake system can be detected using suitable pressure sensors and used to detect wading.

[0027] Water and / or a water level can also be detected by an increase in driving resistance during the water crossing, as driving resistance increases when driving through water compared to driving on level ground. This is primarily due to the higher water resistance compared to air resistance, as water has a higher density. The respective driving resistance can be measured by the drive torque or the drive power of the motor. Interfering influences such as gradient, wind, etc. can be corrected when processing the respective measured values.

[0028] To detect wading and / or to measure the water level, a preferably additional measuring device comprising a float can be used. Distance sensors of a parking aid, which measure based on ultrasound, for example, can also be used.

[0029] To detect wading and / or to determine the water depth in the area of ​​the vehicle, means, steps, components and / or measures of other methods and devices described in the publications mentioned above may also be used.

[0030] The aforementioned further means, components, steps, constituents and / or measures of further methods and devices represent aspects of the invention which can also be used independently of the first aspect of the invention mentioned above.

[0031] Within the scope of the invention, it can further be provided that, after detecting wading and / or after detecting that a water level specified by a threshold has been reached or exceeded, protective measures are initiated, for example, to prevent water from being sucked into the engine or, for example, to prevent water from entering the interior by automatically closing the windows. By automatically detecting wading early on using the invention, appropriate measures can be taken fully or partially automatically, either at an early stage or as a preventative measure.

[0032] Further embodiments of the invention are explained in more detail below with reference to the figures. They show: Fig. 1 A vehicle with various sensors and control units, Fig. 2 Height effects of a floating movement of a vehicle, Fig.3 A measuring arrangement for an electrical quantity for water level measurement and Fig. 4 measured values ​​for water level measurements on a radiator surface.

[0033] In the Fig.The passenger car 1 shown in Figure 1 schematically shows its engine 2 with a corresponding electronic engine control unit 3. Furthermore, the front axle 12 and the rear axle 13 as well as a front shock absorber 6 and a rear shock absorber 9 of the chassis of the passenger car 1 can be seen. A ride height sensor 7 is provided on the front shock absorber 6, with which corresponding ride height fluctuations of the body of the passenger car 1 can be detected and corresponding ride height values ​​or ride height signals can be output. A corresponding ride height sensor 8 is provided on the rear shock absorber 9. The two ride height sensors 7, 8 are connected to a control unit 10, which evaluates the respective ride height signals or ride height values ​​output. The control unit 10 contains a corresponding data processing unit for this purpose.Based on the height values ​​and in particular by comparing them with reference values ​​and / or with reference function curves, which each describe a floating movement of the vehicle at predetermined speed values, the control unit 10 can determine whether the passenger car 1 is currently wading through water and / or how high the water level is below the passenger car. A large number of other sensors of the passenger car 1 and / or control units are typically connected to the control unit 10 directly or indirectly via corresponding interfaces and / or data buses. For example, the control unit 10 can also be connected to the engine control unit 3, to a slip sensor and / or to a speedometer. Data output by these can also be used to determine the state of a wading trip and / or the water level.Furthermore, a sensor 4 is provided on the underside of a radiator 5 for the engine cooling water in the front area of ​​the passenger car 1, with which sensor 4 can detect water located below the radiator 5, in particular water reaching the radiator 5. The sensor 4 can also be designed such that, if necessary, a water level of water located below the passenger car 1 can be determined. The sensor 4 can in particular be an electrical sensor that outputs measurement signals based on capacitance measurements and / or conductivity measurements. Several corresponding sensors can be provided on the radiator 5 or on its outer surface. In the passenger car 1, further radiators or cooling surfaces can be provided, on which further corresponding sensors can be provided, for example cooling surfaces of an air conditioning condenser of an air conditioning system.If different radiator surfaces are arranged close to one another but electrically separated, and corresponding sensors are mounted on the different radiator surfaces, the detection and measurement accuracy can be further increased. An air conditioning condenser 11 is provided directly in front of the engine cooler 5. The two facing surfaces of the engine cooler 5 and the air conditioning condenser 11 can also form the capacitive sensor 4. For this purpose, they can be located, for example, at a distance of 0.2 to 20 centimeters from each other, and preferably at a distance of 0.5 to 2 centimeters.

[0034] The sensors in the area of ​​the coolers 5, 11 are connected to a corresponding control or evaluation circuit, for example to the controller 10.

[0035] In Fig.2 shows the ride height effects of a vehicle floating movement. The graphic symbolically shows a measured value curve 20 for a vehicle speed, whereby the vehicle enters a pool of water in which it floats. On the time axis plotted to the right, the vehicle reaches the pool of water at time 23. Measured value curve 21 symbolically represents measured values ​​from a ride height sensor on the rear axle of the vehicle. Measured value curve 22 symbolically represents measured values ​​from a ride height sensor on the front axle of the vehicle. It can be seen from the graphic that the ride height values ​​of a rebound movement go in a negative direction. It can also be seen that a rebound movement already takes place on both axles when entering the pool of water up to time 24. By accelerating the vehicle up to a maximum speed of approx.At 15 km / h at time 25, a noticeable rebound movement occurs compared to the initial ride height of the vehicle. The movement is stronger on the front axle than on the rear axle, but otherwise they rebound essentially parallel. In comparison, during acceleration and braking, when the vehicle is moving without water influence and at low speeds, the axles typically move in opposite directions, caused by the vehicle pitching around its center of gravity.

[0036] The double arrow 27 represents the travel from the spring movement of the vehicle's front axle. In a practical test, this travel was 53 millimeters. The corresponding travel on the rear axle was 23 millimeters.

[0037] To prevent false triggering when detecting wading, other driving situations in which such rebound motion occurs are specifically excluded from the evaluation. It is advantageous, but not absolutely necessary, to install sensors on all four wheels of the vehicle for appropriate ride height measurement.

[0038] For example, cornering typically results in a roll motion on one side of the vehicle. If ride height sensors are mounted on only one side of the axles, sensor signals can indicate a similar rebound motion. To avoid incorrectly classifying the fording motion, values ​​from steering angle sensors, for example, can be taken into account in the evaluation. Roll stabilization is also beneficial here.

[0039] Driving over a hill can also cause rebound movement of both axles of the vehicle. By limiting the speed range in which the wading detection function is triggered, for example, by limiting it to below 40 km / h, rebound movement at a hill can be largely eliminated. This also effectively prevents the function from being triggered by rebound movement caused by aerodynamics at high speeds.

[0040] In Fig. 3 shows a measuring or sensor arrangement 30 which is used for water level measurement, for example in the Fig.1 is suitable for use on a radiator surface. The water level of the water 37 is shown schematically by the double arrow 38. The arrangement comprises two electrodes 32, 33, between which the water 37 penetrates. The electrical resistance between the electrodes 32, 33, which changes depending on the water level, is measured by means of a Wheatstone bridge circuit with two corresponding resistors 35, 36, a voltage source 31, which applies a voltage of 12 volts, for example, to the two electrodes, and by means of a voltmeter 34. In comparison to measuring arrangements without a Wheatstone bridge circuit, the arrangement shown, which is nevertheless relatively simple in design, already results in a relatively high level of measurement accuracy for the respective water level within the electrodes.The measurement accuracy can be adjusted, particularly with regard to different radiator surfaces, by adjusting the two resistors 35, 36, for example, between 1 kOhm and 10 kOhm, and / or by adjusting the voltage supply 31, for example, in the range of 6 to 48 V. To further increase the accuracy, the contact surfaces of the electrodes 32, 33 can also be designed accordingly in terms of their size. The resistance values ​​of the resistors 32, 33 can also advantageously be selected or set depending on the elevation of the intake point in the vehicle.

[0041] Furthermore, it is particularly advantageous to use one or more radiator surfaces of existing vehicle radiators as one or both electrodes 32, 33. The radiator surfaces must, moreover, be electrically decoupled accordingly. Therefore, radiator surfaces of different radiators are particularly suitable as electrodes. For example, a radiator surface of the engine water cooler can be used as the first electrode 32, and a radiator surface of the air conditioning condenser can be used as the second electrode. The respective radiator surfaces are spaced apart from one another at a distance that allows their use as electrodes of the measuring arrangement. A suitable distance of 1.5 centimeters, for example, is used.

[0042] As a result of water flowing between the two cooling surfaces during fording, the two coolers are electrically connected. The voltage drop varies depending on the water level and the corresponding area of ​​the two cooling surfaces flowing through them. This allows the water level to be measured. A further advantage of such an arrangement can be if the intake point of an internal combustion engine is located directly on the cooling surface for engine cooling at an elevated position. This allows the water level to be detected as it rises before it reaches the intake port, and appropriate countermeasures can be taken.

[0043] In Fig. 4 are schematic measurement signals of one of the Fig.3 is shown, the first electrode of which is a cooling surface of the engine water cooler and the second electrode of which is a cooling surface of an air conditioning condenser arranged directly behind the engine water cooler. The vehicle drives up a ramp into a water basin, the water level of which reaches above the lower edge of the respective cooling surfaces. Curve 40 shows the corresponding speed of the vehicle. Curve 41 shows the measured values ​​of the sensor arrangement. At time 42 the vehicle reaches the water basin, so that water penetrates between the cooling surfaces. The bow wave created in the front area of ​​the vehicle when entering the water basin causes the measurement signal to rise sharply. Shortly after time 42 the vehicle is stopped in the water basin, as a result of which the bow wave subsides somewhat from time 42a to time 43 and the water level between the cooling surfaces drops.This causes the measurement signal to drop again. From time 43 onward, it rises again because the vehicle has since started moving from a standstill and continues to accelerate, causing the bow wave to rise again. Subsequent deceleration of the vehicle causes the bow wave to move forward, causing the measurement signal to drop sharply again until time 44.

[0044] The following describes effects relevant to measurement methods that measure wading and / or water levels based on driving resistance. Driving resistance increases when driving in water compared to driving on dry roads. This is primarily due to the higher water resistance compared to air resistance, as water has a higher density. Driving resistance can be measured, for example, using the drive torque or the drive power of the engine in a motor vehicle, including an electric vehicle. However, interfering influences must be taken into account to obtain an accurate measurement result. For example, it is necessary to identify and exclude driving situations that also cause an increase in driving resistance. Interfering influences and ways of identifying them include: Mountain ride: Can be detected by tilt sensor or level sensor. Trailer driving: Can be identified by electrical connection. Headwind: Plays a role mainly at higher speeds. Cornering resistance: Can be detected by the steering angle sensor. Loose subsoil: Detectable with the wheel speed sensors. Loading conditions: Must be excluded by applying to possible or permissible loading conditions. Flat tire: Can be detected with wheel speed sensors. Acceleration: Can be detected with an acceleration or speed sensor. Driving through snow: Detectable by measuring the outside temperature, e.g. by means of an upper threshold in the range between -5 and +5 degrees Celsius.

[0045] The described devices and system components are controlled, in particular, by computer programs and may also comprise other, known elements of computers and digital control devices, such as a microprocessor, volatile and non-volatile memories, interfaces, etc. The invention can therefore also be implemented, in whole or in part, in the form of a computer program product that, when loaded and executed on a computer, fully or partially effects a process according to the invention. It can be provided, for example, in the form of a data carrier such as a CD / DVD or in the form of one or more files on a server from which the computer program can be downloaded.

Claims

[1] Method for detecting wading of a vehicle (1), wherein during wading a floating movement of the vehicle (1) occurs due to a vehicle-specific wading depth, wherein the vehicle (1) comprises a chassis with a first axle (12) and a second axle (13), wherein at least one first height sensor (7) is provided which is assigned to the first axle (12), wherein at least one second height sensor (8) is provided which is assigned to the second axle (13), wherein height fluctuations of the body of the vehicle (1) can be detected with the height sensors (7, 8) and wherein a decision is made on the basis of sensor values ​​of the height sensors (7, 8) as to whether wading has occurred. [2] Method according to claim 1, characterized by that measured values ​​are recorded for the respective water depth. [3] Method according to one of the preceding claims, characterized bythat the first axle (12) is a front axle and the second axle (13) is a rear axle and that at least one corresponding height level sensor (7, 8) is provided for both the front axle (12) and the rear axle (13). [4] Method according to claim 3, characterized by that a plurality of height sensors (7, 8) are provided for each of the front axle (12) and / or the rear axle (13), so that height fluctuations caused by cornering and / or acceleration can be detected and distinguished from height fluctuations caused by fording. [5] Method according to one of the preceding claims, characterized by that the height sensors (7, 8) are each provided in the area of ​​chassis, spring and / or damping elements (6, 9, 12, 13) of the vehicle (1). [6] Method according to one of the preceding claims, characterized bythat signals from at least one mechanical, electrical, optical and / or other component such as an ultrasonic component, a radar component or a sonar component are used to detect the respective water depth. [7] Method according to one of the preceding claims, characterized by that the height sensor (7, 8) has at least one further component such as an ultrasonic component, a radar component or a sonar component to detect wading and that signals from the further component are used to detect wading. [8] Measuring device for detecting a wading movement of a vehicle (1) comprising a chassis with a first axle (12) and a second axle (13), comprising: - at least one first height sensor (7) associated with the first axle (12) and - at least one second height sensor (8) which is assigned to the second axle (13), wherein height fluctuations of the body of the vehicle (1) can be detected by means of the height sensors (7, 8) and wherein a decision is made on the basis of sensor values ​​from the height sensors (7, 8) as to whether wading is taking place. [9] Measuring device according to claim 8, comprising means for carrying out a method according to one of claims 1 to 7. [10] Measuring device according to claim 8 or 9, comprising at least one further component such as an ultrasonic component, a radar component or a sonar component and a device for processing the sensor values. [11] Vehicle (11) comprising a measuring device according to one of claims 8 to 10.

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