A method to estimate an obstacle height for a motor vehicle, and a motor vehicle

Abstract

Environment perception module 14 determines that a height estimate of obstacle 12 is above a predefined uncertainty level, and transmits a vertical motion request to suspension control module 16, thus

Description

FIELD OF THE INVENTION

[0001] The present invention relates to the field of automobiles. More specifically, the present invention relates to a method to estimate an obstacle height for a motor vehicle. Furthermore, the present invention relates to a motor vehicle that is configured to perform the method. BACKGROUND INFORMATION

[0002] A motor vehicle, in particular an autonomous motor vehicle, needs to have an accurate estimate of surrounding obstacles before it can safely move. These estimates are typically provided by fused camera, radar, ultrasonic and / or LIDAR measurements. Each modality has its own strength and weaknesses that are often complimentary to each other, enabling safe autonomous driving. However, some scenarios are particularly problematic if they elude each modalities strengths. For example, an autonomous vehicle that is commanded to move upon startup. In this scenario, its memory of the surrounding environment is either non-existent or outdated. Therefore, it must rely on its current measurements to estimate the relative positions and heights of surrounding obstacles.

[0003] In particular, LIDARs are sparsely deployed so near-range obstacles are often outside of its field of view. Short range radars can provide excellent range estimates but often provide poor to no elevation angle measurements. Monocular camera images have excellent angular resolution but cannot directly measure range. Ultrasonic sensors provide acceptable range estimates but cannot directly measure elevation angles.

[0004] Therefore, autonomous vehicles must depend on other methods to indirectly measure near-range obstacle heights. For instance, if the obstacles range can be captured from two different perspectives that correspond to different elevation angles, the obstacle height can be triangulated from the range estimates. In particular, the translation difference between the two perspectives may be referred to as the baseline.

[0005] There are several ways to form this baseline. Ideally, the vehicle has two sensors that are mounted at a baseline from each other. For example, stereo cameras are two monocular cameras that may be mounted at a horizontal baseline. Alternatively, this would also work for two ultrasonic sensors mounted on top of each other. Their vertical baseline would allow them to view a target at different elevation angles, permitting height estimates from the range estimates.

[0006] However, many sensor configurations do not have vertical baselines. SUMMARY OF THE INVENTION

[0007] Therefore, it is the object of the present invention to provide a method as well as a motor vehicle, by which an obstacle height is estimated in an improved manner.

[0008] This object is solved by a method as well as a motor vehicle according to the independent claims. Advantageous embodiments are presented in the dependent claims.

[0009] The invention is based on the idea, that instead of a vertical configuration of sensors, a virtual baseline may be formed by a vehicle motion. If the vehicle moves horizontally towards an obstacle, the obstacle will be captured at different elevation angles from the sensor. If the vehicle’s motion and sensor range estimates are known, the obstacle height can be estimated via triangulation. Unfortunately, the precision of this height estimate is strongly correlated by the elevation angle difference and the elevation angle in a horizontal motion only changes insignificantly at close ranges. At these close ranges, the obstacle may be completely outside of a sensor’s field of view. Furthermore, horizontal virtual baselines can only be created if the vehicle can move horizontally, which is not possible in the previously described startup scenario.

[0010] However, vertical motion can also create virtual baselines that are critical for estimating height. By using an electronically controlled suspension, the motor vehicle has the ability to adjust their riding height. These suspensions are typically used to improve a ride quality, minimize aerodynamic drag, or improve off-road clearances. However, also “bouncing” motion may be performed by these suspensions. Consequently, the vertical baseline may be created by altering a vertical position to estimate the height of obstacles, in particular near-range obstacles.

[0011] One aspect of the present invention relates to a method to estimate an obstacle height for a motor vehicle. The method comprises the steps of determining by an environment perception module that a high estimate of an obstacle in a surrounding environment of the motor vehicle is above a predefined uncertainty level, generating a vertical motion request by the environment perception module and transmitting the vertical motion request to a suspension control module of the motor vehicle, modifying a vertical position of a vehicle body of the motor vehicle by controlling an electronically controlled suspension of the motor vehicle by the suspension control module, wherein a sensor device in the vehicle body determines range measurements up the obstacle for at least two different vertical positions of a sensor device, especially by receiving the vertical motion request. The method further comprises the steps of estimating the obstacle height depending on the range measurements, and generating a vertical motion stop request by the environment perception module and transmitting the vertical motion stop request to the suspension control module to stop the vertical motion, if the height estimate of an obstacle is below the predefined uncertainty level.

[0012] In other words, an environment perception module may detect that the high estimates of its surrounding environment are too uncertain for a safe operation of the vehicle that is preferably configured as an autonomous vehicle. For example, the high of at least one obstacle in the vicinity of the motor vehicle may be not sufficiently known. The environment perception module than may send a vertical motion request to a suspension control module of the motor vehicle.

[0013] After receiving the vertical motion request the suspension control module may control an electronically controlled suspension of the motor vehicle to modify a vertical position of the vehicle body. That is, the suspension may be configured to adjust the elevation of the vehicle body. A sensor device that may be located in the vehicle body determines range measurements while the vertical position is modified. In particular, range measurements at a plurality of different vertical positions of the vehicle body may be determined by the sensor device. For example, the sensor device may comprise camera, radar, LIDAR and / or ultrasonic sensors to determine the range measurements. In particular, besides the range measurements of the sensor device also a suspension height measurement at the time of the measurement may be determined, for example by capturing corresponding time stamps for each measurement. These suspension high measurements may be one link in a chain of extrinsic transformations that can relate the perception sensors pose relative to the vehicle environment.

[0014] Then, the obstacle height may be estimated depending on the range measurements. For example, the environment perception module may utilize explicit or implicit triangulation. These trigonometry based methods can estimate an obstacle height from two or more range measurements, given that they were captured at different known heights. Thus, the suspension’s vertical motion may be utilized for the sensor device to capture measurements at varying heights. Alternatively, the sensor device may provide elevation angel measurements at different vertical positions, for example by monocular cameras, wherein an explicit or implicit triangulation may then be used to estimate obstacle heights.

[0015] Finally, if the environment perception module determines that the high estimates of obstacles are below the predefined uncertainty level, a vertical motion stop request may be generated and provided to the suspension control module to stop the vertical motion of the motor vehicle. The motor vehicle may then perform a motion planning with the sufficiently known obstacle heights in the environment.

[0016] The motor vehicle is preferably configured as an autonomous vehicle and the obstacle is preferably a near-range obstacle, for example a curb. The environment perception module and / or the suspension control module may be control units of the motor vehicle or software components of a computer program.

[0017] The advantage of the present invention is that a robustness and accuracy of the estimation of an obstacle height can be improved.

[0018] According to an embodiment the estimation of the obstacle height is performed after a vehicle start at a standstill for a near-range obstacle.

[0019] In another embodiment, the electronically controlled suspension is a hydropneumatic suspension.

[0020] In another embodiment a triangulation is performed with the at least two range measurements at the different vertical positions to estimate the obstacle height.

[0021] In another embodiment the vertical position is modified between a completely raised and a completely lowered suspension.

[0022] In another embodiment the motion request is cyclical and comprises a predefined motion frequency.

[0023] According to another embodiment the motion frequency is dependent on whether occupants are detected in the motor vehicle.

[0024] According to another embodiment, the method is performed in a horizontal motion of the motor vehicle, and wherein the frequency is dependent on the horizontal speed of the motor vehicle.

[0025] In another embodiment the suspensions for each wheel are equally adjusted to modify the vertical position without a role or pitch. Alternatively, the field of view of a sensor device may be prioritized over the height estimation, wherein in this case the suspensions of the wheels are differently adjusted to induce a vehicle roll and / or pitch.

[0026] Another aspect of the present invention relates to a motor vehicle including at least an environment perception module, a suspension control module, an electronically controlled suspension and a sensor device, wherein the motor vehicle is configured to perform according to the preceding aspect.

[0027] Another aspect of the present invention relates to a computer program product including program code means for performing a method according to the preceding aspect. The computer program product may be also regarded as a computer program.

[0028] A still further aspect of a present invention relates to a non-transitory computer-readable storage medium including at least a computer program product according to the preceding aspect.

[0029] Further advantages, features, and details of the invention derive from the following description of preferred embodiments as well as from the drawings. The features and feature combinations previously mentioned in the description as well as the features and feature combinations mentioned in the following description of the figures and / or shown in the figures alone can be employed not only in the respectively indicated combination but also in any other combination or taken alone without leaving the scope of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The novel features and characteristic of the disclosure are set forth in the appended claims. The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate exemplary embodiments and together with the description, serve to explain the disclosed principles. In the figures, the same numbers are used throughout the figures to reference like features and components. Some embodiments of system and / or methods in accordance with embodiments of the present subject matter are now described below, by way of example only, and with reference to the accompanying figures.

[0031] The drawings show in:

[0032] Fig. 1 a motor vehicle according to an exemplary embodiment;

[0033] Fig. 2 a schematic flow chart according an exemplary embodiment of a method.

[0034] In the figures the same elements or elements having the same function are indicated by the same reference signs. DETAILED DESCRIPTION

[0035] In the present document, the word "exemplary" is used herein to mean "serving as an example, instance, or illustration". Any embodiment or implementation of the present subject matter described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

[0036] While the disclosure is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawing and will be described in detail below. It should be understood, however, that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternatives falling within the scope of the disclosure.

[0037] The terms “comprises”, “comprising”, or any other variations thereof, are intended to cover a non-exclusive inclusion so that a setup, device or method that comprises a list of components or steps does not include only those components or steps but may include other components or steps not expressly listed or inherent to such setup or device or method. In other words, one or more elements in a system or apparatus preceded by “comprises” or “comprise” does not or do not, without more constraints, preclude the existence of other elements or additional elements in the system or method.

[0038] In the following detailed description of the embodiment of the disclosure, reference is made to the accompanying drawing that forms part hereof, and in which is shown by way of illustration a specific embodiment in which the disclosure may be practiced. This embodiment is described in sufficient detail to enable those skilled in the art to practice the disclosure, and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the scope of the present disclosure. The following description is, therefore, not to be taken in a limiting sense.

[0039] Fig. 1 shows a schematic side view of a motor vehicle 10 according to an exemplary embodiment. The motor vehicle 10 may be an autonomous vehicle that is configured to estimate a height of an obstacle 12 that may be near the motor vehicle 10. To determine the height of the obstacle 12 the motor vehicle 10 may comprise an environment perception module 14, a suspension control module 16, electronically controlled suspensions 18 and a sensor device 20.

[0040] The environment perception module 14 may determine that a height estimate of the obstacle 12 is not sufficiently known. This may occur after a vehicle start when the motor vehicle 10 is at a standstill. In particular, in this scenario, the environment perception module 14 cannot rely on previous motion or history data to estimate the height of the obstacle 12. Therefore, the uncertain height estimates may prevent the autonomous vehicle 10 from safely moving horizontally. In this case, the height estimate of the obstacle 12 may be above a predefined uncertainty level, wherein the environment perception module 14 may then generate a vertical motion request. This vertical motion request may be transmitted to the suspension control module 16.

[0041] The suspension control module 16 may be configured to control the suspension 18 of the motor vehicle 10. The suspension 18 may be a hydropneumatic suspension that is electronically controlled by the environment perception module 16.

[0042] In particular, the suspension control module may modify a vertical position of a vehicle body by controlling the electronically controlled suspension 18 so that also the vertical position of the sensor device 20 is adjusted in a vertical position. While modifying the vertical position the sensor device 20 may determine range measurements of the obstacle 12, in particular, for at least two different vertical positions.

[0043] For this purpose, the vertical motion may be binary, i.e. completely raised or completely lowered. Alternatively, the motion may be cyclical comprising a predefined motion frequency. Thus, the requested vertical motion message may include the desired frequency of the motion. Since high frequency vehicle motion can be uncomfortable for passengers, this frequency may be dependent of whether occupants are detected in the motor vehicle 10. The signal and method for occupant detection may come from another vehicle module that is not shown in this figure. Also, in case the motor vehicle 10 is driving in a horizontal direction, the frequency may also be dependent on the vehicle’s horizontal speed.

[0044] The vertical motion of the motor vehicle 10 may create a virtual vertical baseline for height estimation. In particular, the wheel’s suspensions 18 may be equally adjusted to modify the vehicle’s vertical position without affecting its role or pitch.

[0045] The environment perception module 14 may then estimate the obstacle height depending on the range measurements. For example, the environment perception module 14 may utilize a triangulation from the two or more range measurements that are recorded at different known heights of the motor vehicle. After the environment perception module 14 determines, that the obstacle height is sufficiently estimated and below the predefined uncertainty level, a vehicle motion stop request may be generated and transmitted to the suspension control module 16 to stop the vertical motion of the motor vehicle 10.

[0046] In another example, the vertical motion to estimate the obstacle height may also be requested while the motor vehicle 10 is moving horizontally. In particular, the vehicle may undergo a consistent cycle of the following:

[0047] Detecting that the height estimates are too uncertain for further horizontal motion; sending a request to stop the vehicle’s current horizontal motion; and sending a request to the vehicle’s suspension control module 16 to induce the vertical motion; estimating the height of the obstacle 12 and reducing its uncertainty by the environment perception module 14. The vehicle is then able to move horizontally again, albeit slowly and over a short distance. If the vehicle again encounters a region of height uncertainty the aforementioned steps may be repeated.

[0048] In Fig. 2 a schematic flow chart of a method to estimate an obstacle height for a motor vehicle 10 is shown.

[0049] In a step S1 an environment perception module 14 determines that a height estimate of an obstacle 12 in the surrounding environment of the motor vehicle 10 is above a predefined uncertainty level.

[0050] In a step S2 a vertical motion request is generated by the environment perception module 14 and transmitted to a suspension control module 16 of the motor vehicle 10.

[0051] In a step S3 a vertical position of a vehicle body is modified by controlling an electronically controlled suspension 18 of the motor vehicle 10, wherein range measurements of the obstacle 12 are determined for at least two different vertical positions of a sensor device 20.

[0052] In a step S4 the obstacle height is estimated depending on the range measurements.

[0053] Finally, in a step S5 a vertical motion stop request is generated by the environment perception module 14 and transmitted to the suspension control module 16 to stop the vertical motion of the suspensions 18, if the height estimate of the obstacle 12 is below the predefined uncertainty level. List of reference signs 10 Motor vehicle 12 Obstacle 14 Environment perception module 16 Suspension control module 18 Suspension 20 Sensor device S1-S5 Method steps

Claims

1. A method to estimate an obstacle height for a motor vehicle (10), comprising the steps of:- determining by an environment perception module (14) that a height estimate of an obstacles (12) in the surrounding environment of the motor vehicle (10) is above a predefined uncertainty level;- generating a vertical motion request by the environment perception module (14) and transmitting the vertical motion request to a suspension control module (16) of the motor vehicle (10);- modifying a vertical position of a vehicle body of the motor vehicle (10) by controlling an electronically controlled suspension (18) of the motor vehicle (10) by the suspension control module (16), wherein a sensor device (20) in the vehicle body determines range measurements of the obstacle (12) for at least two different vertical positions of the sensor device (20);- estimating the obstacle height depending on the range measurements;- generating a vertical motion stop request by the environment perception module (14) and transmitting the vertical motion stop request to the suspension control module (16) to stop the vertical motion, if the height estimate of the obstacle (12) is below the predefined uncertainty level.

2. The method according to claim 1, wherein the estimation of the obstacle height is performed after a vehicle start at a standstill for a near-range obstacle (12).

3. The method according to claims 1 or 2, wherein the electronically controlled suspension (18) is a hydropneumatic suspension.

4. The method according to any one of claims claim 1 to 3, wherein a triangulation is performed with the at least two range measurements at the different vertical positions to estimate the obstacle height.

5. The method according to any one of the preceding claims, wherein the vertical position is modified between a completely raised and completely lowered suspension.

6. The method according to any one of the preceding claims, wherein the motion request is cyclical and comprises a predefined motion frequency.

7. The method according to claim 6, wherein the motion frequency is dependent on whether occupants are detected in the motor vehicle (10).

8. The method according to claim 6 or 7, wherein the method is performed in a horizontal motion of the motor vehicle (10), and wherein the frequency is dependent on the horizontal speed of the motor vehicle (10).

9. The method according to any one of the preceding claims, wherein the suspensions for each wheel are equally adjusted to modify the vertical position without a roll or pitch.

10. A motor vehicle (10) comprising an environment perception module (14), a suspension control module (16), an electronically controlled suspension (18) and a sensor device (20), wherein the motor vehicle (10) is configured to perform a method according to any of the preceding claims.13

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