Road unevenness detection by evaluating operating current of electric vehicle drive

Abstract

A condition of a traffic lane traveled by a vehicle having an electric drive is determined. In this case, an operating current of the electric drive is detected. At least one current fluctuation in the operating current is determined. And identifying the uneven position of the carriageway according to the current fluctuation. A signal is generated that reflects the location of occurrence of the current fluctuation and / or the unevenness of the lane. And outputting the occurrence place or the uneven position of the traffic lane as the uneven position of the traffic lane. A corresponding computer program product is also described.

Description

Background Art

[0001] Driving over unevenness in the driving lane reduces comfort and may also cause wear in the vehicle frame. It is known to detect unevenness such as potholes in order to be able to warn the vehicle of potholes and, if necessary, to adapt the chassis to an upcoming pothole or other unevenness.

[0002] It is known from document DE 102014214729 A1 to determine potholes with the aid of height sensors or inertial sensors. These sensors incur additional hardware costs. Summary of the Invention

[0003] The object of the present invention is to provide a possibility of detecting unevenness in the driving lane in a cost-effective manner.

[0004] This object is solved by the subject matter of the independent claims. Further features, characteristics, embodiments and advantages result from the dependent claims and the description.

[0005] It is proposed to detect unevenness in the driving lane based on current fluctuations in an electric traction drive. It has been recognized that driving over unevenness in the driving lane causes a torque change on the drive, on the one hand when driving into a lower driving lane position (unevenness) such as a pothole, and on the other hand when driving out onto a driving lane that is higher than the defective position in the driving lane. The former causes a temporary torque drop, while the latter causes a torque peak. Due to the electromotive force characteristic of the electric drive (generator effect, reaction of the torque change on the drive current), these changes in torque will be recognized in the current flowing through the electric drive during operation. Thereby, it is possible to infer unevenness in the driving lane by determining current fluctuations. This allows for cost-effective detection of unevenness in the driving lane and, if necessary, detection of the associated occurrence location (location of the unevenness in the driving lane), where this can also be used to adapt the driving parameters of the drive or the chassis in preparation for the unevenness in the driving lane, and in particular can be used to set up a database with the location where the unevenness in the driving lane is located.

[0006] A method for determining the condition of a driving lane is described. A vehicle with an electric drive device travels on the driving lane. In this case, the electric drive device is a traction drive device. The operating current of the electric drive device is detected. In this case, the measurement or other determination of the operating current performed during the engine regulation or engine control of the electric drive device can be utilized. In this case, the actual current value of the motor regulation can be output as a signal reflecting the operating current, and these signals form the basis for determining at least one current fluctuation. The operating current can be detected as the phase current of the motor of the electric drive device, or as the operating DC current of the inverter feeding the motor (or it can also be detected based on variables in the engine control or engine regulation). The operating current can be detected by utilizing the regulation quantity or control quantity within the engine control or engine regulation. The determination of the current fluctuation can be performed by detecting the fluctuation in the regulation deviation of the engine regulation (which characterizes the unevenness of the driving lane), or based on the target value / actual value difference in the engine regulation, or based on the harmonics in the operating current (which characterize the unevenness of the driving lane). Since the control quantity or regulation quantity is logically related to the operating current, or partially or fully reflects the operating current, the control quantity or regulation quantity can also be referred to as the operating current in terms of detection.

[0007] Determine at least one current fluctuation occurring in the operating current. The cause of this current fluctuation is driving over an unevenness of the driving lane. In this case, the change in the current generating the rotating field is not referred to as a current fluctuation. Only the fluctuation relative to the target operating current is referred to as a current fluctuation. The target operating current can be, in this case, the (polyphase) phase current (alternating current) or the DC current for powering the inverter, where the current fluctuation refers to the deviation from the target waveform of the current, that is, the deviation from the target three-phase current flowing as the phase current in the motor of the drive device, or the deviation from the DC current powering the inverter. Therefore, the current fluctuation is a change relative to the phase alternating current or its sinusoidal waveform curve, or a change in the supply DC current of the inverter. The current or current fluctuation can be measured by means of a current sensor (shunt, Hall element, measuring transformer, etc.). In particular, the current fluctuation can be determined by filtering the operating current by means of a high-pass filter, or by correlating with the signal waveform characterizing the influence of driving over the unevenness of the driving lane on the operating current of the electric drive device.

[0008] Based on the current fluctuations, it is recognized that at the moment when the current fluctuations occur, the vehicle is passing over an unevenness in the driving lane. The presence of an unevenness in the driving lane is recognized based on the current fluctuations, where a variable (lane quality) characterizing the unevenness in the driving lane is output, in particular its severity or that the lane is uneven. This can be used (even regardless of the location of occurrence) to correspondingly set the chassis, set the driving mode (such as the sensitivity of the accelerator pedal or the sports mode versus the economy mode), and / or output information detectable by the user, which indicates the unevenness in the driving lane and, if necessary, its severity or quality. In particular, based on the current fluctuations, it is recognized that the vehicle is located at the position of an unevenness in the driving lane. The location where the vehicle was or is at the moment when the current fluctuations occur corresponds to the location of occurrence of the current fluctuations. This location of occurrence can be determined by a (preferably global) positioning method, in particular a satellite-assisted and / or mobile communication network-assisted positioning method. A signal reflecting the location of occurrence of the current fluctuations is generated. The signal can include a location description, in particular a global location description or a location description of a road in a map display. The signal at least reflects the location of occurrence and can also reflect the intensity and / or length (duration) of the current fluctuations, or reflect the severity of the unevenness in the driving lane. The signal or the location of occurrence it reflects is output as the position of the unevenness in the driving lane. In other words, the signal corresponds to the location of occurrence of the position of the unevenness in the driving lane and can also reflect the quality and / or quantity of the unevenness in the driving lane. Therefore, a signal reflecting the location of occurrence of the current fluctuations is generated and output. The signal can be output as a database entry.

[0009] Preferably, the location of occurrence is output to a database. In this database, the location of occurrence is stored, and preferably further data characterizing the position of the unevenness in the lane (severity, length, size, etc.) is stored together. The database can be located in the vehicle, in particular in the navigation device of the vehicle. The database can be located in a mobile device configured to perform a navigation function. Preferably, the navigation function is combined with the database there. Thus, the navigation device or the navigation function can display navigation data combined with the entries of the database. In addition, the database can be provided outside the vehicle, for example as a database accessible by the navigation device in the vehicle. The navigation device retrieves the entries of the database and preferably combines them with the navigation data (or navigation display) of the navigation device. Such a navigation device can be a device fixedly installed in the vehicle (and configured for corresponding communication), or can be a mobile device configured for corresponding communication and configured to perform a navigation function (such as in the form of application software).

[0010] Preferably, the duration of the current fluctuation (the time between two consecutive current fluctuations or the distance equivalent value of this duration) or the intensity and / or the shape of the current fluctuation are determined. From this, quality or quantity characteristics of the current fluctuation can be derived, which can be stored or output as a signal in a location-logical association with the occurrence location of the carriageway unevenness, in particular.

[0011] In particular, the duration (the time between two consecutive current fluctuations or the distance equivalent value) and / or the form can be compared with a preset duration and / or shape. Preferably, a similarity value is determined during the comparison, which is a measure of the similarity between the determined duration and / or shape and the preset duration and / or shape. Different intensities can be preset such that the preset intensity with the greatest similarity to the determined intensity can be determined. To determine the similarity, correlation in the time domain or frequency domain can be used, where the result of the correlation reflects the similarity. Vector similarity can also be determined, or similarity, in particular the similarity value, can be determined with the aid of a neural network. The similarity value reflects the intensity of the similarity and increases as the intensity of the similarity increases. Preferably, the occurrence location is only output when the similarity value exceeds a preset extreme value. In this way, carriageway unevennesses that are erroneously detected as positive can be filtered out.

[0012] The embodiment provides that, before determining the current fluctuation, a current change that is logically associated with the change in the target speed received via the operating interface is subtracted from the operating current. Since this change in the target speed (corresponding to the target acceleration) is known, this change can be subtracted from the determined operating current by subtraction. In addition, since the current change caused by this change in the target speed has a significantly smaller slope steepness compared to the current fluctuation caused by the carriageway unevenness, the current fluctuation component attributable to the change in the target speed can be suppressed by high-pass filtering or the like.

[0013] It can be provided that at least one current fluctuation in the operating current is only determined, the signal is only generated, and / or the occurrence location is only output when the current fluctuation is determined while the vehicle speed is higher than a preset speed threshold. In other words, if the vehicle speed is not higher than the preset speed threshold, this current fluctuation is not detected as a carriageway unevenness. The speed threshold can be, for example, 5 km / h or 2 km / h. In this way, it can be avoided that driving over a curbstone when parking or leaving a parking space is erroneously detected as a carriageway unevenness.

[0014] Determining at least one current fluctuation in the operating current preferably provides that, as characteristics of the current fluctuation, the amplitude and / or the slope steepness and / or the frequency components are calculated. This characteristic is mapped to the torque change occurring in the electric drive device due to road surface unevenness, where the torque change is the cause of the current fluctuation. In particular, the amplitude and / or the slope steepness and / or the frequency components are mapped to the intensity of the current fluctuation and thus to the severity of the road surface unevenness. Preferably, the road condition, in particular the road unevenness characteristic, is determined based on the torque change. As the road unevenness characteristic, in particular the depth, severity and / or length of the road surface unevenness are considered.

[0015] The current fluctuation can be mapped to the road condition or the road surface unevenness characteristic by representing the mapped current fluctuation as a time signal or in the frequency domain. Preferably, the location of occurrence is output together with the road condition. This mapping maps the current fluctuation or its characteristics (amplitude, duration, slope steepness) to the quantity or quality of the road surface unevenness.

[0016] This mapping preferably maps the current fluctuation as a frequency domain representation. Thus, the frequency domain representation of the current fluctuation is mapped to the quality or quantity of the position of the lane unevenness. The frequency domain representation can be a complete or partial spectral representation of the current fluctuation, in particular the amplitude of one or more frequency components of the current fluctuation. In addition, the current fluctuation can also be mapped in the time domain. In addition, the current fluctuation can be mapped with the aid of a neural network. The neural network (or generally a system configured for machine learning) can reflect the relationship between the road condition (or the road surface unevenness characteristic) and the current fluctuation occurring in the drive device due to this road condition.

[0017] In addition, a method for operating an electric drive device of a vehicle based on the road condition or based on the road surface unevenness is described. It is provided to determine the driving route. Before reaching the location of occurrence of the road surface unevenness determined by the method according to any one of the preceding claims, a road unevenness warning is output. Alternatively or additionally, the electric drive device or the chassis of the vehicle can be adjusted for a lane with a higher unevenness, for example by increasing the elasticity of the suspension and / or by reducing the maximum drive power. In addition, if the vehicle passes the location of occurrence at the lowest speed or a higher speed, that is, at a speed that is too high and thus not adapted to the road surface unevenness, resulting in an increase in vehicle wear, the vehicle wear counter can be incremented.

[0018] A computer program product is described which is configured to execute the method. The computer program product has an input interface (such as a function header, etc.) for values reflecting the time-varying process of the operating current. The computer program product has a program segment which determines time fluctuations among these values. The input interface is configured to pass these values to the program segment. The computer program product has an output interface (such as a function header, etc.) which outputs an occurrence value characterizing the current occurrence of the fluctuation, or outputs the occurrence location of the fluctuation as the current position of the vehicle at the moment of the fluctuation occurrence. The program segment is configured to pass the occurrence value or the occurrence location to the output interface. A determination device can also be provided, which is configured to execute the method. The determination device can be configured as a processor and an associated program memory, wherein a computer program is stored in the program memory, and when the computer program runs on the processor, the method is implemented.

Claims

1. A method for determining the condition of a lane traveled by a vehicle having an electric drive device, comprising the following steps: - Detecting the operating current of the electric drive device; - Determining at least one current fluctuation in the operating current; - Generating a signal reflecting the occurrence location of the current fluctuation; and - Outputting the occurrence location as the position of a lane unevenness and / or outputting a variable characterizing the lane unevenness.

2. The method according to claim 1, wherein the occurrence location is output to a database and stored therein, where the database is located inside or outside the vehicle.

3. The method according to claim 1 or 2, wherein the duration and / or the intensity and / or the shape of the current fluctuation are determined, the duration and / or the intensity and / or the shape are compared with a preset duration and / or shape, a similarity value is determined, the similarity value is a measure of the similarity between the determined duration and / or shape and the preset duration and / or shape, and the occurrence location is output only when the similarity value exceeds a preset extreme value.

4. The method according to any one of the above claims, wherein before determining the current fluctuation, a current change logically associated with a change in a target speed received via an operating interface is subtracted from the operating current.

5. The method according to any one of the above claims, wherein at least one current fluctuation in the operating current is determined, the signal is generated and / or the occurrence location is output only when the current fluctuation is determined while the vehicle speed is higher than a preset speed threshold.

6. The method according to any one of the above claims, wherein determining at least one current fluctuation in the operating current provides that the amplitude and / or the slope steepness and / or the frequency components of the current fluctuation are calculated as characteristics of the current fluctuation, and the characteristics are mapped to a torque change occurring in the electric drive device and causing the current fluctuation.

7. The method according to claim 6, wherein the road condition, in particular the road unevenness characteristics, are determined based on the torque change.

8. The method according to any one of the above claims, wherein the current fluctuation is mapped to the road condition by mapping the current fluctuation as a representation in the time domain or in the frequency domain, and the occurrence location is output together with the road condition.

9. The method according to claim 8, wherein the mapping is a mapping that maps the current fluctuation to a representation in the frequency domain, and / or is a mapping that maps the current fluctuation by means of a neural network, the neural network reflecting the relationship between the road condition and the current fluctuation occurring in the drive device due to the road condition.

10. A method for operating an electric drive device of a vehicle according to road conditions, wherein a driving route is determined, and before reaching the occurrence location output by the method according to any one of the above claims, a road unevenness warning is output and / or the electric drive device or chassis of the vehicle is adjusted for a lane with a higher unevenness and / or the vehicle wear counter is incremented when driving through the occurrence location at the lowest speed or a faster speed.

11. A computer program product configured to execute the method according to any one of the above claims, wherein the computer program product has: an input interface for values reflecting the time course of the operating current ； a program segment for determining time fluctuations in the values; and an output interface that outputs an occurrence value characterizing the current occurrence of the fluctuations or outputs the occurrence location of the fluctuations as the current position of the vehicle at the occurrence time of the fluctuations.