Ultrasound sensor-based load condition detection of a vehicle

Abstract

Method for detecting the loading state of a vehicle (1) by means of at least one ultrasonic sensor (3) wherein the at least one ultrasonic sensor (3) is arranged on a movable part of the vehicle (2), wherein the movable part of the vehicle (2) is a gullwing door or a tailgate, and wherein the ultrasonic sensor is arranged on an inside of the movable part of the vehicle (2), comprising at least the steps: a) Detection of the distance R0 of a vehicle part (2) in a stationary state to a stationary object (5) using at least one ultrasonic sensor (3); b) Detection of the current distance R i of the ultrasonic sensor (3) to the stationary object (5) during a loading / unloading process of the vehicle (1), c) Calculation of the change in distance ΔR from the difference between the distance R0 and the distance R i , d) Calculation of the vehicle's loading state B (1) based on the change in distance ΔR and, if applicable, a vehicle-dependent variable.

Description

[0001] The present invention relates to a method for detecting the loading state of a vehicle by means of at least one ultrasonic sensor, wherein the method comprises at least the steps: a) detecting the distance R0 of a vehicle part in the stationary state to a stationary object by means of the at least one ultrasonic sensor; b) detecting the current distance R i of the ultrasonic sensor to the stationary object during a loading / unloading process of the vehicle, c) Calculation of the distance change ΔR from the difference between the distance R0 and the distance R i ; d) calculating the loading condition B of the vehicle based on the distance change ΔR and, if appropriate, a vehicle-dependent variable. Furthermore, the present invention includes a driving assistance system suitable for carrying out the method according to the invention, as well as a vehicle with such a driving assistance system.

[0002] The traffic situation has become significantly more diverse and therefore more confusing in recent decades. In addition to the overall increase in traffic volume, new user groups have been or are currently emerging, such as autonomous vehicles or pedelecs, which, with their diverse movement profiles and characteristics, require ever greater attention from the driver. Attempts are being made to counteract this complexity by outsourcing parts of the driver's tasks to the vehicle in the form of driver assistance systems. These have the potential to actively and autonomously intervene in the driving process, thus both increasing safety and reducing the driver's workload. The disadvantage of this development is that, in turn, the number of vehicle components increases and the electronics become more complex. This can contribute to increased costs and a greater susceptibility to errors.Overall, technical solutions that contribute to greater safety and enhanced comfort in vehicles while maintaining the same complexity as existing systems would be desirable. This generally applies to driver assistance systems whose control mechanisms are designed for both moving and stationary traffic.

[0003] An important starting point for increasing driving safety is ensuring a vehicle's correct load is maintained. This step can be essential, as excessive or incorrect loads can drastically impair vehicle handling. Therefore, there is a need for technical solutions and processes capable of detecting "unfavorable" load conditions and informing the driver with the least possible technical effort.

[0004] Patent literature contains various approaches for determining the load status of vehicles, particularly motor vehicles. One feasible technical approach, for example, is to determine the load status based on the behavior of the wheels or tires while the vehicle is moving.

[0005] For example, DE 10 2007 023 069 A1 discloses a method for detecting the load of a motor vehicle, wherein a load of the vehicle and / or a change in the load of the vehicle is detected based on an analysis of the contact patch lengths of the wheels (VR, HR), which occur in particular during braking and / or acceleration of the motor vehicle and / or during cornering of the motor vehicle.

[0006] Another detection option using the wheels / tires of a vehicle is disclosed in DE 10 2010 031 464 A1. This teaches a method in which the load condition of a motor vehicle is detected based on the tire pressures obtained from wheel speed information and / or information from directly measuring tire pressure monitoring systems. The pressure difference occurring between the tires of the front and rear axles during a journey, which results from the temperature change caused by the varying increases in wheel loads during rolling, is evaluated.

[0007] Ultrasonic sensors are a widely used sensor type in vehicles. These sensors are used to perform a wide variety of monitoring tasks on vehicles. For example, these sensors are used to monitor the vehicle's surroundings in moving traffic, such as monitoring a parking or reversing maneuver. Patent literature also lists other applications for this type of sensor.

[0008] Thus, EP 2 951 376 B1 describes a method for automatically moving a pivotable flap of a motor vehicle, in particular a tailgate, comprising a drive mechanism controllable via a control device at least for automatically opening the flap and a device for detecting any obstacle in the path of movement of the flap, comprising at least one ultrasonic sensor, wherein the detection device continuously determines the distance to any obstacle and the control device controls the movement of the flap depending on the detection result.

[0009] Another application of ultrasonic sensors in collision protection is specified in DE 10 2013 018 839 A1. This discloses a collision protection device for a vehicle door of a vehicle that can be automatically adjusted along a travel path (X) between a closed position and an open position (Xo). The device comprises a distance sensor and a control and evaluation unit. While the vehicle door is in the open position (Xo), a protection zone upstream of the vehicle door in the closing direction is monitored for the approach of an object using the distance sensor and the control and evaluation unit. Upon detection of an object in the protection zone, at least one protective measure is initiated.

[0010] A further design of anti-pinch protection is described in DE 10 2010 038 705 A1.

[0011] From DE 10 2015 011 928 A1 a method for operating a safety system of a motor vehicle is known, in which environmental sensors of the motor vehicle are evaluated to determine at least one collision parameter describing a possible collision with a collision partner and in doing so a loading state of the motor vehicle is taken into account.

[0012] From DE 10 2014 001 031 A1 a method for assisted loading of a motor vehicle is known, which is loaded with at least one transport load, which is detected by a sensor device and output as loading information by an output device of the motor vehicle.

[0013] The disadvantage of these solutions is that the load condition detection only allows significant statements when the vehicle is moving or that the sensors used are only used for one task.

[0014] The present invention is based on the object of specifying a method for detecting the load of a vehicle, a driving assistance system for a vehicle and a vehicle with such a driving assistance system, which solves at least one of the problems described above.

[0015] The object is achieved according to the invention by the features of the independent claims. Advantageous embodiments of the invention are specified in the subclaims.

[0016] In particular, the invention provides a method for detecting the loading condition of a vehicle by means of at least one ultrasonic sensor, wherein the at least one ultrasonic sensor is arranged on a movable vehicle part, wherein the movable vehicle part is a wing door or a tailgate, at least comprising the steps: a) detection of the distance R0 of a vehicle part in the stationary state to a stationary object by means of the at least one ultrasonic sensor; b) Detection of the current distance R i of the ultrasonic sensor to the stationary object during a loading / unloading process of the vehicle, c) Calculate the change in distance ΔR from the difference between the distance R0 and the distance R i , and d) Calculation of the loading condition B of the vehicle based on the change in distance ΔR and, if applicable, a vehicle-dependent variable.

[0017] Surprisingly, it was discovered that the method described above makes it possible to reliably and reproducibly measure the loading condition of a vehicle, thus contributing to increased driving safety. The measured variable is the change in distance from a stationary reference point, measured using an ultrasonic sensor. Depending on the relative arrangement of the stationary reference point to the ultrasonic sensor, the additional load results in a relative movement of the loaded / unloaded vehicle, which is reflected in an increase or decrease in the distance from the stationary reference point. In particular, this method can be used to determine conditions in which the vehicle is overloaded or conditions in which the vehicle is asymmetrically loaded. The method also has the advantage that these conditions can be determined while the vehicle is stationary.This is significantly more advantageous than prior art methods, which determine the load condition while the vehicle is moving. The method according to the invention is therefore capable of informing the driver of potential hazards or areas for optimization before the start of a journey. This allows dangerous situations to be avoided right at the beginning of a journey. A further advantage of this method is that the complexity of technical components and sensors can be kept to a minimum. In the best case scenario, it is possible to utilize existing sensors that are used for other tasks. This results in a very cost-effective solution, and the maintenance effort and susceptibility to errors of the overall system are reduced.

[0018] The loading condition of a vehicle refers to situations or conditions in which, in addition to the weight of the vehicle itself, there is an additional weight load in the form of a payload of parts not permanently attached to the vehicle. It also refers to the vehicle not having any additional payload, i.e., the vehicle is essentially "empty" or unloaded. A load or payload refers to an additional and significant weight load on a vehicle. A weight load is significant if, for example, it accounts for more than 0.1 to 1 percent of the vehicle's weight. Possible significant and common weight loads or payloads include suitcases, furniture, water crates, etc.

[0019] The method is carried out using at least one ultrasonic sensor. Ultrasonic sensors known from the prior art can be used for the method, as long as they have sufficient length accuracy. Preferably, ultrasonic sensors with a resolution of at least 1 cm, more preferably 0.5 cm, and further preferably 0.1 cm can be used. These resolutions allow the loading conditions of vehicles to be determined with sufficient accuracy.

[0020] In step a), the distance R0 of a stationary vehicle part from a stationary object is detected by means of at least one ultrasonic sensor. The method therefore takes place when the vehicle is stationary. This means that the vehicle is stationary and, in particular, not moving. This can be the case, for example, with a motor vehicle in a parked position. The distance measured by the ultrasonic sensor from a vehicle part to the stationary object is used as a starting point for characterizing the vehicle load. The ultrasonic sensor can be attached to both movable and fixed vehicle parts. Movable vehicle parts include, for example, the driver and passenger doors or the tailgate of the vehicle. A fixed vehicle part is, for example, the underbody or the roof of a vehicle.Stationary objects within the meaning of the invention are, for example, the floor on which the vehicle is parked, the ceiling of a garage or its side walls. However, other stationary objects can also be used as fixed points, as long as they do not change their position in space during the measurements. In the case of moving vehicle parts, the detection of the distance R0 is expediently carried out after the moving vehicle part has reached an end position. This can be the case with tailgates, for example, when the tailgate has reached its end position and is no longer moving. The distance can be detected once, or the measurement can be repeated several times in succession and an average of the measured values ​​can be taken to determine the distance.

[0021] In step b) the loading / unloading of the vehicle is carried out by detecting the current distance R iof the ultrasonic sensor to the stationary object. By changing the vehicle's payload, either by increasing the weight through a load or by reducing the weight through unloading the vehicle, the distance R i of the ultrasonic sensor attached to the vehicle to the stationary object. The detection of the current distance can be carried out either by a single measurement of the sensor after loading or unloading or by a continuous measurement of the distance. In the latter case, the distance data used for the calculation are those which result in the case of equilibrium, i.e., in particular in cases where the measured value R i is constant. However, it is also possible to use not only individual values ​​for the calculation, but also averages over 3, 5, or 10 measurements in the steady state.

[0022] In step c) the calculation of the distance change ΔR is carried out from the difference between the distance R0 and the distance R i The changes in distance, i.e. the difference between the initial and final states, are greater the greater the weight difference between the individual states.

[0023] In step d), the vehicle's loading condition B is calculated based on the change in distance ΔR and, if applicable, a vehicle-dependent variable. The change in distance is generally proportional to the change in vehicle weight. For example, if an ultrasonic sensor is attached to the floor of a vehicle, an increase in weight due to a load will reduce the measured distance to the ground. The absolute magnitude of the change in distance is a function of, for example, the vehicle's suspension and / or tires. If these vehicle-specific constants are known, the loading or unloading that has taken place can be calculated from the changes in distance. If necessary, absolute values ​​can be obtained by calibration with known weights. The correlation between the two variables, weight and, for example, change in suspension travel, can be stored in a vehicle memory and used to calculate absolute variables.However, it is also possible to give an initial estimate of the loading or unloading based only on the absolute change in distance, for example in the form that if the distance changes by more than or equal to X centimeters, the permissible load of the vehicle is exceeded.

[0024] Within a preferred embodiment of the method, the detection of the current distance R iof the ultrasonic sensor to the stationary object while the vehicle is at rest. In particular, continuous measurement of the distance allows better statistics of the entire process to be obtained and thus more reliable values ​​about the vehicle's condition. Furthermore, continuous measurement can help to obtain further information about the type of load. If, for example, several plateau values ​​​​occur in the range of the current distance, it can be concluded that several objects have been loaded. This information is particularly valuable if, for example, the use of several sensors has shown that the vehicle is unevenly loaded. In this case, the driver can be asked to check whether a more even distribution of the weight can be achieved.

[0025] According to the invention, the at least one ultrasonic sensor is arranged on a movable vehicle part, wherein the ultrasonic sensor is arranged on an inner side of the movable vehicle part. Arranging the ultrasonic sensor on a movable vehicle part, such as a tailgate, can be advantageous because in these cases, a better temporal allocation of the loading or unloading process is possible. Thus, the method according to the invention can be started when the electronics of the tailgate are started, and the measurement of the distance in the basic state can take place when the distance of the ultrasonic sensor on the tailgate to the stationary object, for example a garage ceiling, reaches a constant value.

[0026] According to a further characteristic of the method, ultrasonic sensors can be used for load detection, which simultaneously serve as collision or anti-pinch protection for the moving vehicle parts. To reduce the complexity of the vehicle's electrical systems and save on sensors, it has proven particularly advantageous to use ultrasonic sensors arranged in moving vehicle parts such as doors or tailgates for the method according to the invention. These sensors are typically used as anti-pinch protection or contact protection for the moving parts. Within the scope of the invention, the same sensors can perform a dual function and simultaneously be used for repeated distance measurements.

[0027] In an additional aspect of the method, at least two spaced-apart ultrasonic sensors can be used for load detection. By using multiple spaced-apart ultrasonic sensors, a better spatial resolution for the location of loading or unloading can be achieved within the scope of the method according to the invention. Furthermore, the use of multiple sensors can improve the statistics of the method, for example, by averaging the change in distance between the individual sensors.

[0028] According to a further embodiment of the method, vehicle settings can be changed and / or instructions can be issued to a driver via a driving assistance system based on the determined load condition of the vehicle. It has also proven useful not only to passively store the determined load condition in a memory, but also to recommend or even implement further measures based on the evaluation. All measures that are usually adjusted as a function of the total weight of the vehicle can contribute to the optimization of the vehicle settings. The measures can affect the entire vehicle, individual axles, or even individual axle halves. Overall, the vehicle can be better stabilized for future driving despite the existing load.Alternatively, it is possible for the driver to be informed via a display that he should reduce the vehicle's payload or that he should change the weight distribution of the payload in the vehicle.

[0029] According to a modified embodiment of the method, the data from two ultrasonic sensors on opposite sides of the vehicle can be used for evaluation and, in a further step, a warning can be given based on the change in distance between the respective sensors if the vehicle is unevenly loaded. If, for example, one sensor is mounted on the right end of a tailgate and another sensor on the left end, different distance changes will result for both sensors if the vehicle is loaded on one side. The difference in the change in distance between the respective sensors can then be used to determine whether an additional load has occurred, for example, in the middle of the vehicle (both distance changes of the same magnitude) or whether the additional load has occurred in the left or right half of the vehicle. In the latter case, different distance changes will result for both sensors.Overall, this procedure can contribute to increasing driving safety, as the vehicle's driving behavior can change dramatically when the load is extremely different.

[0030] In a preferred embodiment of the method, in a further step e), the loading state B of the vehicle can be stored in a memory. The loading state B of the vehicle can be expressed by any value that is proportional to the loading state of the vehicle. This can, for example, be the measured value of the change in distance or another processed value, such as the value converted into kilograms of payload. The loading state can also be stored purely qualitatively, for example in the form of a state "unloaded", "loaded", or "overloaded". The vehicle's central memory, for example, can be used as the memory. However, it is also possible to use external memory in the form of a smartphone or watch.This can advantageously help to provide the current loading status for further loading / unloading operations even after the vehicle electronics have been switched off and the vehicle has been restarted.

[0031] According to the invention, there is also provided a driving assistance system for determining the loading state of a vehicle, comprising at least one ultrasonic sensor, an evaluation unit, a storage unit and an output unit, wherein the at least one ultrasonic sensor (3) is arranged on a movable vehicle part (2), wherein the movable vehicle part (2) is a wing door or a tailgate, and wherein the driving assistance system is designed to detect, by means of the at least one ultrasonic sensor, a distance R0 of a vehicle part in the stationary state to a stationary object, the current distance R iof the ultrasonic sensor to a stationary object after or during a loading / unloading process, a distance change ΔR from the difference between the distance in state R0 and the distance in state R i , and to determine the vehicle's loading condition B based on the distance change ΔR and, if appropriate, one or more vehicle-dependent variables. The method according to the invention is particularly suitable for integration into a driving assistance system that prevents or reduces potential hazards associated with incorrect vehicle loading either autonomously or via graphic or acoustic instructions to a driver. Possible output units can be optical or acoustic output units, which can be provided either separately from the driving assistance system or via existing vehicle systems.

[0032] In a preferred embodiment, the driving assistance system can also be designed to store the loading state B of the vehicle in a memory.

[0033] According to a further preferred embodiment of the driving assistance system, in a further step e), the vehicle's load status B can be stored in a memory, the driver can be informed of the load status, and further suggestions for action can be made. The driving assistance system can thus either intervene independently in the vehicle's mechanical or electrical system or prompt the driver to do so immediately or at the next opportunity. However, it is also possible for the system to simply inform the driver that the vehicle's load is OK.

[0034] Within a further preferred embodiment of the driving assistance system, the further suggested actions can be selected from the group consisting of changing the suspension, changing the ground clearance, changing the tire pressure, changing the loading pattern, reducing the vehicle load, or combinations thereof. As a function of the calculated state, the driving assistance system can suggest either one or a bundle of measures that can contribute to a more risk-free loading of the vehicle. However, it is also according to the invention for the driving assistance system to carry out individual measures on the vehicle itself and / or prompt the driver to carry out one or more measures themselves.

[0035] The invention also relates to a motor vehicle with the driving assistance system according to the invention. The driving assistance system according to the invention is particularly suitable for installation in a motor vehicle, since this vehicle class can accommodate large payloads, which can significantly influence the vehicle's driving physics. This results in a significant increase in safety.

[0036] According to a further feature, the motor vehicle can have a movable tailgate with at least one ultrasonic sensor. For the advantages of this configuration, reference is made to the explanations in the context of the driving assistance system according to the invention and in the context of the method according to the invention.

[0037] According to a modified embodiment, the motor vehicle can have an ultrasonic sensor on each of the driver and passenger doors. For the advantages of this configuration, reference is made to the explanations in the context of the driving assistance system according to the invention and in the context of the method according to the invention.

[0038] According to a further preferred embodiment, the motor vehicle can have at least one ultrasonic sensor on a movable vehicle part and at least one ultrasonic sensor on a stationary vehicle part. The use of two different ultrasonic sensors on two different vehicle parts can be particularly advantageous for motor vehicles, since the different mounting locations allow different contributions from the movable and stationary body parts to be determined. In this way, average distance values ​​can be obtained, which provide more significant information about the load condition and are significantly less prone to errors.

[0039] These and other aspects of the invention will become apparent and clear from the embodiments described below. Individual features disclosed in the embodiments may constitute an aspect of the present invention alone or in combination. Features of the various embodiments may be transferred from one embodiment to another. Likewise, possible advantages of the method according to the invention are also to be considered disclosed for possible driving assistance systems according to the invention and motor vehicles with these systems, and vice versa.

[0040] They show schematically the: Fig. 1 shows a possible sensor arrangement for implementing the method according to the invention. Two sensors (3) are mounted on the doors (2) of a car (1); Fig. 2 shows a possible sensor arrangement for carrying out a method not according to the invention. A sensor (3) is mounted in the tailgate (2) of a car (1); and Fig. 3 shows a possible sensor arrangement for implementing the method according to the invention. A sensor (3) is mounted in the tailgate (2) of a car (1).

[0041] The Fig. 1 shows a possible embodiment of a sensor arrangement on a motor vehicle (1). The front view shows a car (1) which has two wing doors (2) as the driver's and passenger doors. An ultrasonic sensor (3) is attached to the inside of each of the wing doors and can be used, among other things, as an anti-pinch device. In the method according to the invention, this ultrasonic sensor (3) is used, when the wing doors are open, as a sensor for measuring the distance between the ultrasonic sensor (3) and the stationary object (the ground (5)). This distance (4) defines the distance value R0 when the wing doors (2) are open. When the car is loaded, the distance (4) between the ground (5) and the ultrasonic sensor (3) decreases because, for example, the suspension is further compressed by the load. The change in distance is proportional to the payload.It is possible to consider the change in distance of each ultrasonic sensor (3) individually or to use an average of the changes in distance of both ultrasonic sensors (3) to calculate the overall change in distance. By using two individual values, it is possible to determine any uneven loading of the car (1). For example, with an asymmetric load on the right-hand side, the distance of the right ultrasonic sensor (3) to the ground (5) decreases, while the distance at the left ultrasonic sensor (3) remains constant or even increases. In this way, asymmetric loads of the car (1) can be detected.

[0042] The Fig. Figure 2 shows a sensor arrangement of a passenger car (1) not according to the invention. In this embodiment, an ultrasonic sensor (3) is attached to a movable tailgate (2) of the passenger car (1). The distance to a stationary object (5), in this case, for example, a garage ceiling (5), is measured by the ultrasonic sensor (3). The distance R0 results from the distance between the ultrasonic sensor (3) and the garage ceiling (5). The cone of the ultrasonic sensor is provided with the reference symbol (4) in this figure. During loading, the body of the passenger car (1) lowers slightly, which results in an increase in the distance between the ultrasonic sensor (3) and the garage ceiling (5). The magnitude of the weight increase of the passenger car (1) can be calculated from the absolute change in the distance between the ultrasonic sensor (3) and the garage ceiling (5).The weight increase due to the load can be temporarily stored in a driving assistance system and, based on the determined values, further instructions can be given to the driver or measures to change the driving dynamics of the vehicle can be initiated autonomously.

[0043] In the Fig.Figure 3 shows a further embodiment of a possible sensor arrangement. This example shows the rear of a car (1), wherein the ultrasonic sensor (3) is attached to the movable tailgate (2) of the car (1). The ultrasonic sensor (3) is attached to the inside of the movable tailgate (2), and the distance to the stationary object is measured, in this case to the ground (5). The measuring cone (4) of the ultrasonic sensor (3) determines the distance between the open tailgate (2) and the ground (5). If the car (1) is loaded or unloaded, the distance between the ultrasonic sensor (3) and the ground (5) changes, and the increase or decrease in the vehicle weight can be determined based on the absolute change in the distance. Based on the determined increase or decrease in the vehicle weight, a driving assistance system can recommend or initiate further measures to counteract incorrect loading of the car (1). List of reference symbols 1 vehicle 2 Movable vehicle part (vehicle door, tailgate) 3 ultrasonic sensors 4 Ultrasonic measuring section 5 Stationary object (floor / ceiling)

Claims

[1] Method for detecting the loading state of a vehicle (1) by means of at least one ultrasonic sensor (3), wherein the at least one ultrasonic sensor (3) is arranged on a movable vehicle part (2), wherein the movable vehicle part (2) is a wing door or a tailgate, and wherein the ultrasonic sensor is arranged on an inner side of the movable vehicle part (2), at least comprising the steps: a) detection of the distance R0 of a vehicle part (2) in the stationary state to a stationary object (5) by means of the at least one ultrasonic sensor (3); b) Detection of the current distance R i of the ultrasonic sensor (3) to the stationary object (5) during a loading / unloading process of the vehicle (1), c) Calculate the change in distance ΔR from the difference between the distance R0 and the distance R i , d) Calculation of the loading condition B of the vehicle (1) based on the change in distance ΔR and, if applicable, a vehicle-dependent variable. [2] Method according to claim 1, wherein the detection of the current distance R i of the ultrasonic sensor (3) to the stationary object (5) is carried out continuously in the stationary state of the vehicle (1). [3] Method according to claim 2, wherein ultrasonic sensors (3) are used for load detection, which are simultaneously used for collision or trapping protection of the movable vehicle parts (2). [4] Method according to one of the preceding claims, wherein at least two spaced-apart ultrasonic sensors (3) are used for load detection. [5] Method according to one of the preceding claims, wherein, based on the determined loading state of the vehicle (1), vehicle settings are changed and / or instructions are issued to a driver via a driving assistance system. [6] Method according to one of the preceding claims, wherein the data of two ultrasonic sensors (3) on opposite sides of the vehicle are used for evaluation and, on the basis of the change in distance of the respective sensor (3), a warning is given in a further step of an uneven loading of the vehicle (1). [7] Method according to one of the preceding claims, wherein in a further step e) the loading state B of the vehicle (1) is stored in a memory. [8] Driving assistance system for determining the loading state of a vehicle (1) at least comprising an ultrasonic sensor (3), an evaluation unit, a storage unit and an output unit, wherein the at least one ultrasonic sensor (3) is arranged on a movable vehicle part (2), wherein the movable vehicle part is a wing door or a tailgate, wherein the ultrasonic sensor is arranged on an inner side of the movable vehicle part (2), and wherein the driving assistance system is designed to detect by means of the at least one ultrasonic sensor (3) a distance R0 of a vehicle part (2) in the stationary state to a stationary object (5), the current distance R i of the ultrasonic sensor (3) to a stationary object (5) after or during a loading / unloading process, a distance change ΔR from the difference between the distance in state R0 and the distance in state R i, and to determine the loading condition B of the vehicle (1) based on the change in distance ΔR and, if necessary, one or more vehicle-dependent variables. [9] Driving assistance system according to claim 8, wherein in a further step e) the loading state B of the vehicle (1) is stored in a memory, the driver is informed about the loading state and further suggestions for action are made. [10] Driving assistance system according to claim 9, wherein the further suggested actions are selected from the group consisting of changing the suspension, changing the ground clearance, changing the tire pressure, changing the loading pattern, reducing the load of the vehicle or combinations thereof. [11] Motor vehicle with a driving assistance system according to one of claims 8 to 10. [12] Motor vehicle according to claim 11, wherein the motor vehicle (1) has a movable tailgate (2) with at least one ultrasonic sensor (3). [13] Motor vehicle according to one of claims 11 or 12, wherein the vehicle has an ultrasonic sensor (3) on each of the driver's and passenger doors (2). [14] Motor vehicle according to one of claims 11 to 13, wherein the vehicle has at least one ultrasonic sensor (3) on a movable vehicle part (2) and at least one ultrasonic sensor (3) on a non-movable vehicle part.

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