Object detection apparatus for vehicle

A roadside object present at the side of a subject vehicle travel path and a preceding vehicle at a speed equal to or greater than a predetermined speed are detected based on points derived by transmitting an electromagnetic beam forward of the subject vehicle and projecting reflection points obtained onto a two-dimensional plane, a determination is made when the preceding vehicle passes near the roadside object as to whether it moved toward the travel path within a predetermined time before and after the passage, and the roadside object is not determined to be the obstacle when it is determined to have moved toward the travel path, thereby preventing the roadside object from being misidentified as the obstacle owing to erroneous recognition of it having intruded into the travel path of the subject vehicle when detecting the object using an electromagnetic beam.

TECHNICAL FIELD

This invention relates to an object detection apparatus for a vehicle, more particularly to an apparatus configured to prevent erroneous detection occurring due to a roadside object or other object detected using an electromagnetic beam being transferred to a vehicle ahead of the subject vehicle.

BACKGROUND ART

It is a common practice to detect a pedestrian or other object moving laterally ahead of a traveling vehicle by utilizing points formed by transmitting an electromagnetic beam forward of the subject vehicle to obtain reflections points that are projected onto a two-dimensional plane, and the technique described in Patent Document 1 listed below is an example in this regard. This conventional technique determines whether the object is a pedestrian or the like by comprehensive consideration of its lateral velocity, position and size.

PRIOR ART REFERENCE

Patent Document

SUMMARY OF THE INVENTION

Problem to be Solved by the Invention

However, it sometimes happens that when the vehicle ahead passes by the roadside object detected outside the travel path of the subject vehicle, the reflection points of the roadside object are dragged by the reflection points of the vehicle ahead and transferred to those of the vehicle ahead, and this transfer is sometimes erroneously recognized as lateral movement of the object.

Specifically, in a driving environment such as shown inFIG. 4A, when, as shown inFIG. 4B, the preceding vehicle passes by a pole or other roadside object detected outside the travel path of the subject vehicle, the reflection points of the roadside object are dragged by the reflection points of the preceding vehicle and transferred to those of the preceding vehicle, so that the roadside object is sometimes erroneously recognized as an obstacle that has intruded (moved laterally) into the subject vehicle travel path.

The technique described in the aforesaid Patent Document 1 has not been able to prevent such erroneous recognition because it uses the lateral velocity and the like of the objects for the detection.

Therefore, this invention is directed to overcoming the foregoing problem by providing an object detection apparatus for a vehicle that, in the case of detecting an object using an electromagnetic beam, prevents a roadside object from being erroneously recognized and determined to have intruded into the travel path of the subject vehicle.

Means for Solving the Problem

In order to achieve the object, as recited in claim1, this invention is configured to have an object detection apparatus for a vehicle equipped with obstacle determination means that determines whether an object detected based on points derived by transmitting an electromagnetic beam forward of the subject vehicle and projecting reflection points obtained onto a two-dimensional plane is an obstacle constituting an obstruction to advance of the subject vehicle, comprising subject vehicle travel path estimation means that estimates a travel path of the subject vehicle; roadside object/preceding vehicle detection means that detects a roadside object present at a side of the travel path and a preceding vehicle traveling ahead on the travel path at a speed equal to or greater than a predetermined speed based on the derived points; and roadside object movement determination means that determines, when the preceding vehicle passes near the roadside object, whether the roadside object has moved toward the travel path within a predetermined time before and after the preceding vehicle passing near the roadside object; wherein the obstacle determination means does not determine the roadside object to be the obstacle when the roadside object is determined to have moved toward the travel path.

In the apparatus recited in claim2, the roadside object movement determination means establishes regions at rear left and rear right of the preceding vehicle and determines whether the roadside object has moved toward the travel path within the established regions, and the obstacle determination means does not determine the roadside object to be the obstacle when the roadside object is determined to have moved toward the travel path within the regions.

In the apparatus recited in claim3, the obstacle determination means corrects a moving speed of the roadside object to zero and corrects a position of the roadside object to a position before movement was detected when it is determined that the roadside object has moved toward the travel path.

In the apparatus recited in claim4, the roadside object movement determination means determines a degree of width of a driving lane where the travel path of the subject vehicle is present and establishes an area of the regions based on the determined width degree.

In the apparatus recited in claim5, the predetermined speed is a vehicle speed with the possibility of provoking transfer of the reflection points of the roadside object obtained by transmitting the electromagnetic beam to the preceding vehicle.

Effects of the Invention

As recited in claim1, the object detection apparatus for a vehicle is configured to detect a roadside object present at a side of the travel path and a preceding vehicle traveling ahead on the travel path at a speed equal to or greater than a predetermined speed based on the derived points, determine, when the preceding vehicle passes near the roadside object, whether the roadside object has moved toward the travel path within a predetermined time before and after the passing of the preceding vehicle and not determine the roadside object to be the obstacle when the roadside object is determined to have moved toward the travel path. With this, even if the reflection points of the roadside object should be dragged by the reflection points of the preceding vehicle and transferred to those of the preceding vehicle, when the preceding vehicle passes by the roadside object, it becomes possible to prevent the transfer from being erroneously recognized as lateral movement of the object and determined to be the obstacle. Moreover, it becomes possible by this to minimize unnecessary collision avoidance control.

As recited in claim2, the apparatus is configured to determine whether the roadside object has moved toward the travel path within the established regions, and not determine the roadside object to be the obstacle when the roadside object is determined to have moved toward the travel path within the regions. With this, in addition to the foregoing effects and advantages, it becomes possible to accurately determine whether the roadside object has moved and reliably determine whether the roadside object is the obstacle and also possible to reduce the processing required for the determination because the region to be determined can be restricted.

As recited in claim3, the apparatus is configured to correct a moving speed of the roadside object to zero and corrects a position of the roadside object to a position before movement was detected when it is determined that the roadside object has moved toward the travel path. With this, in addition to the foregoing effects and advantages, it becomes possible to reliably monitor the roadside object concerned after passing of the preceding vehicle.

As recited in claim4, the apparatus is configured to determine a degree of width of a driving lane where the travel path of the subject vehicle is present and establishes an area of the regions based on the determined width degree. With this, in addition to the effects and advantages, it becomes possible to establish the regions more appropriately, so that whether the roadside object has moved can be accurately determined to more reliably determine whether the roadside object is the obstacle.

As recited in claim5, the predetermined speed is a vehicle speed with the possibility of provoking transfer of the reflection points of the roadside object obtained by transmitting the electromagnetic beam to the preceding vehicle. With this, in addition to the effects and advantages, it becomes possible to reduce the processing required for the determination to the minimum necessary.

DESCRIPTION OF THE EMBODIMENT

A mode for implementing the object detection apparatus for a vehicle according this invention is explained with reference to the attached drawings in the following.

Embodiment

FIG. 1is schematic diagram showing an overall view of an object detection apparatus for a vehicle according to an embodiment of this invention.

InFIG. 1, the symbol10indicates a vehicle (hereinafter called “subject vehicle” having a four-cylinder internal combustion engine (engine; designated “ENG” inFIG. 1)12installed in front. The output of the engine12is inputted to an automatic transmission (designated “T/M” inFIG. 1)14. The automatic transmission14is a stepped automatic transmission with five forward speeds and one reverse speed that suitably regulates the transmission ratio of the output of the engine12transmitted to left and light front wheels16so as to drive the front wheels.16and propel the subject vehicle10as the left and right rear wheels20are made to follow.

A warning device22comprising an audio speaker and an indicator is installed near the driver's seat of the subject vehicle10for wanting the driver audibly and visually. A brake pedal24located on the floor at the driver's seat of the subject vehicle10is connected through a brake booster26, master cylinder30and brake hydraulic mechanism32to brakes (disc brakes)34installed at the individual left and right front wheels16and rear wheels20.

When the driver steps on the brake pedal24, the pressing force is amplified by the brake booster26, the master cylinder30uses the amplified force to generate braking pressure, and the brakes34installed at the individual front wheels16and rear wheels20are operated through the brake hydraulic mechanism32to slow the subject vehicle10. A brake switch36mounted near the brake pedal24outputs an ON signal when the driver operates the brake pedal24.

The brake hydraulic mechanism32is equipped with, inter alia, a group of electromagnetic solenoid valves interposed in oil passages connected to a reservoir, a hydraulic pump, and a motor for driving the hydraulic pump (none of which are shown). The group of electromagnetic solenoid valves is connected to an ECU (electronic control unit)38through a drive circuit (not shown), whereby the four brakes34are configured to be operated independently of one another by the ECU38, separately of the operation of the brake pedal24by the driver.

Further, an electric motor40for steering assistance is installed near the front wheels to assist steering. Specifically, a mechanism that converts rotation of a steering wheel transmitted from a steering shaft and the like to reciprocating motion of a rack through a pinion to steer the front wheels via tie rods (not shown) is provided on its rack with the electric motor40.

The electric motor40is also connected to the ECU38through a drive circuit (not shown). When an obstacle must be avoided by steering, the ECU38operates the electric motor40to help the driver avoid the obstacle by steering.

The front of the subject vehicle10is equipped with a radar (laser-scanning radar) unit42. The radar unit42detects an object present ahead of the subject vehicle10(a preceding vehicle or other object) by transmitting a laser beam (electromagnetic beam (carrier wave)) in the forward direction of the subject vehicle10and receiving the laser beam reflected by the object.

The output of the radar unit42is sent to a radar output processing ECU (electronic control unit)44comprising a microcomputer. The radar output processing ECU44calculates the relative distance to the object by measuring the time from the transmission of the laser beam to the return of the reflected laser beam and further differentiates the relative distance to determine the velocity relative to the object. Moreover, the direction of the object is detected from the direction of the reflected beam, thereby obtaining two-dimensional data, on the object.

The output of the radar output processing ECU44is sent to the ECU (electronic control unit)38. Although not illustrated, the ECU38is configured as a microcomputer comprising, inter alia, a CPU, RAM, ROM and I/O circuit.

Wheel speed sensors46are installed near the respective front wheels16and rear wheels20and output pulse signals once every predetermined rotation angle of the wheels. A steering angle sensor52is installed near a steering wheel50provided at the driver's seat of the subject vehicle10and produces an output proportional to the steeling angle of the steering wheel50input by the driver. A yaw rate sensor54is installed near the center of gravity of the subject vehicle10and produces an output proportional to the yaw rate (angular velocity) around a vertical axis (yaw axis) of the subject vehicle10.

Further, a crank-angle sensor60is installed near a crankshaft (not shown) of the engine12and outputs a pulse signal indicating the crank angle, and a manifold absolute pressure sensor62is installed in an intake manifold (not shown) and outputs a signal corresponding to the absolute pressure inside the intake manifold (indicative of engine load). A throttle opening sensor64is installed near a throttle valve (not shown) and outputs a signal corresponding to the throttle opening.

The outputs of the aforesaid sensor group are also sent to the ECU38. The ECU38counts the outputs of the four wheel speed sensors46and by averaging them, for example, ascertains a vehicle speed indicative of the travel speed of the subject vehicle10, and also counts the output of the crank-angle sensor60to ascertain the engine speed NE.

In addition, a navigation device70is mounted in the subject vehicle10. The navigation device70comprises a current position detection unit70a, a navigation processing unit70b, a map data memory unit70c, an input unit70d, and a display unit70e.

The current position detection unit70ais equipped with a positioning signal receiver70a1for receiving a GPS (Global Positioning System) signal or other such positioning signal and a gyroscope70a2for outputting a signal corresponding to the orientation in the horizontal plane or the tilt angle relative to the vertical direction of the subject vehicle10, and calculates the current position of the subject vehicle10by autonomous navigation based on the received positioning signal or the outputs of the gyroscope70a2and wheel speed sensors46.

The map data memory unit70ccomprises a CD-ROM or other memory medium and stores map (road) data including the width, intersections, right-turn lanes and the like of the road where the subject vehicle10is driving along. The input unit70dcomprises switches, a keyboard and the like, and the display unit70eis equipped with a display.

By accessing the map (road) data stored in the map data memory unit70c, the navigation processing unit70buses the display unit70eto display, for example, the current position of the subject vehicle10obtained by the current position detection unit70aor the position of the subject vehicle10inputted to the input unit70d.

The navigation processing unit70band the ECU38are communicably interconnected, and the navigation processing unit70boutputs to the ECU38data specifying the position on the roadmap data where the subject vehicle10is driving.

FIG. 2is a flowchart showing the operation of the apparatus shown inFIG. 1.

Now to explain, in S (Step)10, the detection data of the radar unit42is read. Specifically, the radar unit42transmits an electromagnetic beam forward of the subject vehicle10as shown inFIG. 4B, and reflection points produced by the beam reflected from all objects present ahead are used to detect the objects.

Within the detection range of the radar unit42(indicated by symbol42ainFIG. 4B), objects are captured or detected as reflection points of the electromagnetic beam. When these reflection points are projected onto a two-dimensional plane on scanner data comprising the forward direction (fore-aft direction) of the subject vehicle10and the direction orthogonal thereto (lateral direction) and stored in the memory of the radar output processing ECU44, an object is detected as a cluster of reflection points (point cloud) because the multiple object reflection points of the object are distributed continuously close together.

Here, to reiterate the issue addressed by this invention: in a driving environment such as shown inFIG. 4A, when, as shown inFIG. 4B, a preceding vehicle102passes by pole or other roadside object100detected outside the travel path of the subject vehicle10, reflection points100aof the roadside object100are dragged by (forced along) reflection points102aof the preceding vehicle (vehicle ahead)102and transferred to those of the vehicle ahead102, so that the roadside object100is sometimes erroneously recognized as obstacles that intruded (moved). The object of this invention is to overcome this inconvenience.

Returning to the explanation of the flowchart ofFIG. 2, next, in S12, the vehicle speed and yaw rate of the subject vehicle10(the motion state of the subject vehicle) are detected from the outputs of the wheel speed sensors46and the yaw rate sensor54, and the travel path10aof the subject vehicle10is estimated from the detected motion state. Alternatively it is possible to acquire data regarding the road the subject vehicle10is driving along by accessing the map data memory unit70cof the navigation device70.

Next, in S14, it is determined whether a roadside object(s)100such as a pole has been detected at the side of the estimated travel path of the subject vehicle10.

When the result in S14is NO, the following processing steps are skipped and when it is YES, the program proceeds to S16, in which it is determined whether a preceding vehicle (indicated by symbol102inFIG. 4) has been detected on the estimated travel path10aof the subject vehicle10, more specifically it is determined whether a preceding vehicle102has been detected that is traveling ahead on the estimated travel path of the subject vehicle10at a speed equal to or greater than a predetermined speed.

The “predetermined speed” is a vehicle speed capable of provoking transfer of the reflection points100aof the roadside object100. In other words, the “predetermined speed” is a vehicle speed that might provoke transfer of reflection points100aof the roadside object100obtained by transmitting the electromagnetic beam to the preceding vehicle102.

When the result in S16is NO, the following processing steps are skipped, and when it is YES, the program proceeds to S18, in which regions104are established at the rear left and rear right of the preceding vehicle102. As shown inFIG. 3, the regions104are separately established on a two-dimensional plane (on scanner data stored in a memory of the aforesaid radar output processing ECU44) on the left and right sides reward of the preceding vehicle102(traveling in the direction of the arrow).

The regions104are divided to the left and right of the preceding vehicle102so as to avoid the area directly behind the preceding vehicle102. This is for enhancing detection accuracy with consideration to the fact that the area directly behind is situated near the middle the driving lane (where the travel path10aof the subject vehicle10is present) and frequently has manholes and the like installed in the road surface.

In S18, it is alternatively possible to define the area (size) of the regions104as a fixed value. Further, it is also possible to determine the width degree of the driving lane where the travel path10aof the subject vehicle10is present by an appropriate method and define the area of the regions104based on the determined width degree. For example, in a case such as when the driving lane is narrow, left and right regions104of suitably reduced area can be defined.

Next, in S20, it is determined, when the preceding vehicle102passes near the roadside object (Pole)100, whether the roadside object100has moved from the road side toward the travel path10aof the subject vehicle10, i.e., the roadside object100has moved laterally in the regions104within a predetermined time before and after the passing of the preceding.

More specifically, in S20, it is determined, when the preceding vehicle102passes near a roadside object (Pole)100, whether the roadside object100(more exactly; its reflection points100a) has moved (has moved laterally) within either established region104toward the travel path10aof the subject vehicle10within the predetermined time before and after the preceding vehicle passing near the roadside object. The “predetermined time” is a very short time.

When the result in S20is NO, the following processing steps are skipped and when it is YES, i.e., when it is determined that the roadside object100(more exactly its reflection points100a) has moved toward the travel path10a, the program proceeds to S22, in which the roadside object100is not determined to be an obstacle and is determined to be a stationary object.

In the case where an obstacle is determined, another routine not shown in the drawings is executed to determine the possibility of colliding with the obstacle in the travel path10aof the subject vehicle10and respond to a finding that collision is possible by executing collision avoidance assistance control such as by issuing a warning with the warning device22(or braking by means of the brake hydraulic mechanism32or steering assistance by means of the electric motor40), but no obstacle has not been determined here, so that no collision avoidance assistance control is performed.

Further, when it is determined in S22that the roadside object100has moved toward the travel path10a, the moving speed of the roadside object100is corrected to zero and the position of the roadside object100is corrected to its position before movement was detected.

As set out in the foregoing, this embodiment is configured to have an object detection apparatus for a vehicle (102) equipped with obstacle determination means (ECU38, S10) that determines whether an object detected based on points derived by transmitting an electromagnetic beam forward of the subject vehicle (10) and projecting reflection points obtained onto a two-dimensional plane is an obstacle constituting an obstruction to advance of the subject vehicle (10), comprising: subject vehicle travel path estimation means (ECU38, S12) that estimates a travel path (10a) of the subject vehicle (10); roadside object/preceding vehicle detection means (ECU38, S14, S16) that detects a roadside object (100) present at a side of the travel path and a preceding vehicle (102) traveling ahead on the travel path (10a) at a speed equal to or greater than a predetermined speed based on the derived points: and roadside object movement determination means (ECU38, S18, S20) that determines, when the preceding vehicle (102) passes near the roadside object (100), whether the roadside object (100) has moved toward the travel path (10a) within a predetermined time before and after the preceding vehicle (102) passing near the roadside object (100); wherein the obstacle determination means does not determine the roadside object (100) to be the obstacle when the roadside object (100) is determined to have moved toward the travel path (ECU38, S22). With this, even if the reflection points of the roadside object100should be dragged by the reflection points of the preceding vehicle102and transferred to those of the preceding vehicle102, when the preceding vehicle102passes by the roadside object100, it becomes possible to prevent the transfer from being erroneously recognized as lateral movement of the object and determined to be an obstacle. Moreover, it becomes possible by this to minimize unnecessary collision avoidance control, such as the issuing of warnings by the warning device22, braking by the brake hydraulic mechanism32, and steeling assistance by the electric motor40.

Further, in the apparatus, the roadside object movement determination means establishes regions (104) at rear left and rear right of the preceding vehicle (102) and determines whether the roadside object (100) has moved toward the travel path (10a) within the established regions (104), and the obstacle determination means does not determine the roadside object (100) to be the obstacle when the roadside object (100) is determined to have moved toward the travel path within the regions (S18, S20, S22). With this, in addition to the foregoing effects and advantages, it becomes possible to accurately determine whether the roadside object100has moved and reliably determine whether the roadside object100is the obstacle and also possible to reduce the processing required for the determination because the region to be determined can be restricted.

Further, in the apparatus, the obstacle determination means corrects a moving speed of the roadside object (100) to zero and corrects a position of the roadside object (100) to a position before movement was detected when it is determined that the roadside object (100) has moved toward the travel path (10a, S22). With this, in addition to the foregoing effects and advantages, it becomes possible to reliably monitor the roadside object100concerned after passing of the preceding vehicle102.

Further, in the apparatus, the roadside object movement determination means determines a degree of width of a driving lane where the travel path of the subject vehicle is present and establishes an area of the regions (104) based on the determined width degree (S18). With this, in addition to the effects and advantages, it becomes possible to establish the regions more appropriately, so that whether the roadside object100has moved can be accurately determined to more reliably determine whether the roadside object100is the obstacle.

Further, in the apparatus, the predetermined speed is a vehicle speed with the possibility of provoking transfer of the reflection points of the roadside object (100) obtained by transmitting the electromagnetic beam to the preceding vehicle (S16). With this, in addition to the effects and advantages, it becomes possible to reduce the processing required for the determination to the minimum necessary.

Although the roadside object is illustrated as a pole in the foregoing, it should be noted that the roadside object is not limited to the pole but include any type whose electromagnetic beam reflection points might transfer to those of the preceding vehicle.

Further, although a laser radar unit was disclosed as the device for transmitting the electromagnetic beam, a microwave radar unit can be used instead or in addition.

INDUSTRIAL APPLICABILITY

According to this invention, a roadside object present at the side of a subject vehicle travel path and a preceding vehicle at a speed equal to or greater than a predetermined speed are detected based on points derived by transmitting an electromagnetic beam forward of the subject vehicle and projecting reflection points obtained onto a two-dimensional plane, a determination is made when the preceding vehicle passes near the roadside object as to whether it moved toward the travel path within a predetermined time before and after the passage, and the roadside object is not determined to be an obstacle when it is determined to have moved toward the travel path, thereby preventing the roadside object from being misidentified as an obstacle owing to erroneous recognition of it having intruded into the travel path of the subject vehicle when detecting the object using an electromagnetic beam.

DESCRIPTION OF SYMBOLS