Negative obstacle detection with stereo camera and long range radar

A negative obstacle detection system for a vehicle comprises a stereo camera mountable to the vehicle to provide a forward facing image and a long range radar mountable to the vehicle to emit a signal in a forward direction from the vehicle. An electronic control unit receives data from the stereo camera and the long range radar to determine if a negative obstacle may be located in a forward proximity to the vehicle.

TECHNICAL FIELD

The present disclosure relates to automotive vehicles, and more particularly to driver assistance systems or automotive vehicles.

BACKGROUND

The advancements in sensor technology available have led to the ability to improve safety systems for vehicles. Additionally, improving passenger comfort is desirable. Therefore, arrangements and methods for detecting and avoiding pot holes on roadways are becoming available. However, due to the geometry of sensor locations available relative to the possible pot holes detection in time to provide a desired response by the vehicle is typically only at low vehicles speeds and/or to rear suspension components. Also, the greater the vehicle speed the more damage or discomfort that is likely occur. Thus, improving the distance from the vehicle at which potholes can be detected is desirable.

SUMMARY

A negative obstacle detection system for a vehicle comprises a stereo camera mountable to the vehicle to provide a forward facing image and a long range radar mountable to the vehicle to emit a signal in a forward direction from the vehicle. An electronic control unit receives data from the stereo camera and the long range radar to determine if a negative obstacle may be located in a forward proximity to the vehicle.

A method of detecting a negative obstacle in proximity to a vehicle comprises performing a first detection analysis on an image provided by a stereo camera, performing a second detection analysis on an image provided by the stereo camera, and performing a third detection analysis on a signal received by a radar. An ECU utilizes the first detection analysis, the second detection analysis and the third detection analysis to determine whether a negative obstacle is present in a forward proximity to the vehicle.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is in no way intended to limit the disclosure, its application, or uses. For purposes of clarity, the same reference numbers will be used in the drawings to identify similar elements.FIG. 1illustrates a vehicle10and a negative obstacle detection system12of the present invention. The obstacle detection system12includes a stereo camera14mounted to provide an image in front of the vehicle10. Throughout the application the relative directions of forward and rear are in reference the direction which an operator for the vehicle10would primarily be facing when operating the vehicle10. The vehicle10may also be a motorcycle.

A long range radar16is also mounted to the vehicle10and directed toward a similar area as the camera14. Several mounting locations for the camera14and radar16are illustrated inFIG. 1. The camera14and radar16may be mounted at the same or different locations on the vehicle10. Other mounting locations may also be desirable. One skilled in the art would be able to determine the desired mounting location for the camera14and the radar16to provide the information required by the obstacle detection system12, as explained below.

The camera14and radar16are connected to an electronic control unit (ECU)18. The ECU18analyzes data from the camera14and the radar16, as described below, to detect negative obstacles22, i.e. potholes. The system12may detect negative obstacles22at an increased distance from the vehicle10, e.g.40meters. The ECU18may be connected to another vehicle system20to provide a signal for altering vehicle10behavior when a negative obstacle22is detected. The vehicle system20may be a steering system, a brake system, a suspension control system, etc. The vehicle10behavior may be altered in one or more ways to avoid the negative obstacle22or to minimize effects of the negative obstacle22on the vehicle10.

Referring toFIGS. 1-5, the camera14is a stereo camera providing a left image24and a right image26. A disparity calculation is performed comparing the differences in the left image24and the right image26, shown at28. The ECU18analyzes the left image24and the right image26and identifies an object22and a distance the object22is located from the vehicle10, shown at30. This is gives a stereo camera output, shown at32.

Using the left image24and the right image26the ECU18performs a first detection analysis34, e.g. hole edge detection shown inFIG. 3. The hole edge detection34is a comparison of differences within the left and/or right image24,26that are caused by the edge of a negative obstacle22.FIG. 3shows an example image24,26using hole edge detection34. The image24,26has a first reflection36that is from the road directly prior to the negative obstacle22. A second reflection38is from within the negative obstacle22, i.e. the side of the pothole. The hole edge detection34is a comparison of the difference in distance that is measured between the first reflection36and the second reflection38. The difference in distance between the first reflection36and the second reflection38is greater than it would be if there were no pothole22. The difference results from the edge of the pothole22causing the second reflection38to be reflecting off a surface that is farther from the vehicle10than it should be. The hole edge detection34is one indicator that a negative obstacle22may be present.

The ECU18also performs a second image analysis,40. The second image analysis is a hole image detection, shown inFIG. 4. The hole image detection40is a analyzes the image24,26and detects the shadow, shown at42that is formed in the pothole22. The first and/or second image24,26will have a difference in light within the pothole22than on the road proximate to the pothole. The image24,26has again has the second reflection38from within the negative obstacle22, i.e. the side of the pothole. Additionally, a third reflection44is from the road directly following the negative obstacle22. The hole image detection34is a comparison of the difference light on the image24,26between the second reflection38and the third reflection44. The difference results from the shadow42that is created in the pothole22causing the second reflection38to be darker than it should be. The hole image detection40is another indicator that a negative obstacle22may be present.

Finally, a third detection element46is performed the by radar16.FIG. 5illustrates the radar16using of hole edge detection46. The radar16emits a signal48which is reflected back to the vehicle10when an object is present. The radar16signal48should reflect off the road in a known manner, as shown by the first reflection36and the third reflection44which reflected off the road proximate to the pothole22. However, the change in road surface resulting from the pothole22causes the second reflection38to be directed back to the vehicle10. The vehicle receives the raw reflected signal48and filters the signals it receives, shown at50, and when the second reflection38is detected the radar16recognizes that an object22is present, shown at52, i.e. the radar recognizes the side of the pothole22as an object. The hole edge detection by the radar16is a third manner of indicating that a negative obstacle22may be present. This is gives a radar output signal, shown at54.

The ECU18combines the first detection element30, the second detection element40and the third detection element44to form a ground map grid56. Additional information60from other vehicle systems may also be used. For example, vehicle data, inertia sensors, GPS etc. The ground map grid56uses all three detection elements30,40,44and the additional information60to determine whether a negative obstacle22is present. When the ECU18determines a negative obstacle22is present a negative obstacle detection (NOD) signal58is sent to at least one other vehicle system18to provide appropriate action.

While the best modes for carrying out the invention have been described in detail the true scope of the disclosure should not be so limited, since those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention within the scope of the appended claims.