Vehicle Sensor Mounting System

A vehicle sensor mounting system includes a tubular bridge structure that spans across the width of the vehicle roof and attaches to existing rooftop anchor points. The mounting system allows camera sensors to have full field-of-view coverage while being as close to the vehicle body as possible to reduce parallax, and not being occluded by the vehicle body or mounting system. The mounting system also allows the cameras to be co-axial with a LiDAR sensor and to minimize parallax. The mounting system has a minimum natural frequency that reduces road vibrations, allowing the sensors to remain in a stable mounting position and minimizes the motion of the sensors relative to the vehicle chassis to reduce misalignment errors in the sensor data. The mounting system includes a front and rear assembly. The rear assembly includes a cable hub assembly that provides a single ingress/egress point for a multi-conductor sensor cable.

TECHNICAL FIELD

This disclosure relates generally to mechanical structures for mounting sensors on rooftops of vehicles.

BACKGROUND

An autonomous vehicle (AV) has many sensors that allow the vehicle to operate autonomously. These sensors typically include a light detection and ranging (LiDAR) sensor for gathering three-dimensional (3D) data (“point cloud”) and multiple radio detection and ranging (RADAR) sensors and camera sensors. The sensors are typically mounted to the rooftop of the vehicle, as well as other locations on the vehicle. The AV typically includes a perception system that detects and tracks objects in the operating environment of the AV using data from the sensors. The perception system “fuses” the sensor data to obtain a more accurate understanding of the objects in the operating environment.

It is desirable that rooftop sensors be mounted in a manner that provides a stable and secure platform for sensors, reduces the impact of road vibrations on the sensors and enhances sensor data fusion by allowing for accurate alignment of the sensors to within a desired mechanical tolerance. Additionally, it is desirable to mount rooftop sensors in a manner that does not damage the integrity of the vehicle by, for example, maintaining weather/water resistance by using existing anchor points (e.g., rails for luggage racks) to attach the mounting system to the roof of the AV to avoid drilling holes in the roof. It is also desirable to maintain service access to the sensors without removing the mounting system from the AV.

SUMMARY

Embodiments of the vehicle sensor mounting system disclosed herein include a front assembly and rear assembly that mount to existing anchor points (e.g., raised side rails, rain gutters) on a vehicle rooftop. The front assembly includes a bridge subassembly that includes two legs and a middle section disposed between the two legs. The intersections of the legs with the middle section forms two bend angles giving the structure its “bridge” profile. The base of the tubular bridge structure (closer to the mounting locations) is wider than the middle section and the legs curve behind the middle section to ensure that forward camera sensors and LiDAR attached to the middle section have full field-of-view (FOV) coverage while being as close to the vehicle body as possible, and not occluding the cameras or LiDAR. The tubular bridge structure also allows forward and backward facing cameras to remain approximately co-axial with the LiDAR sensor and as physically close to each other as possible to minimize parallax. The tubular bridge structure is designed to have a minimum natural frequency to reduce high amplitude, broad spectrum road vibrations, which allows the sensors to remain in a stable mounting position and minimizes the motion of the sensors relative to the vehicle chassis to reduce misalignment errors in the sensor data.

The rear assembly provides mounting platforms for additional camera sensors and antennas (e.g., GPS antennas), and a cable hub assembly that provides a single, weather resistant, ingress/egress point for a multi-conductor sensor cable that provides conductors that attached to the rooftop sensors to provide a communication path for sensor data to an AV computer or other vehicle subsystems.

In an embodiment, an apparatus for mounting vehicle sensors, comprises: a bottom plate having a plurality of connected sections; and a top plate having a plurality of disconnected sections, each disconnected section of the top plate mated to a corresponding connected section of the base plate, forming a tubular bridge structure having two legs, a middle section, a first bend angle separating a first leg from the middle section and a second bend angle separating a second leg from the middle section, wherein the middle section is configured to mount a plurality of sensors.

In an embodiment, an apparatus for mounting vehicle sensors comprises: a bridge structure having two legs, a middle section, a first bend angle separating a first leg from the middle section and a second bend angle separating a second leg from the middle section, wherein the middle section is configured to mount a plurality of sensors; and a cable hub assembly coupled to the middle section, the cable hub assembly including an opening for receiving a multi-conductor sensor cable and an electrical interconnect configured to connect individual conductors of the multi-conductor sensor cable to individual sensors of the plurality of sensors.

In an embodiment, an system for mounting vehicle sensors comprises: a front bridge subassembly including: a bottom plate having a plurality of connected sections; and a top plate having a plurality of disconnected sections, each disconnected section of the top plate mated to a corresponding connected section of the bottom plate, forming a tubular bridge structure having two legs, a middle section, a first bend angle separating a first leg from the middle section and a second bend angle separating a second leg from the middle section, wherein the middle section is configured to mount a first plurality of sensors; a cooling fan disposed inside the middle section of the tubular bridge structure of the front assembly; and a rear bridge subassembly including: a second bridge structure having a set of two legs, a middle section, a first bend angle separating a first leg from the middle section and a second bend angle separating a second leg from the middle section, wherein the middle section is configured to mount a second plurality of sensors; and a cable hub assembly coupled to the middle section, the cable hub assembly including an opening for receiving a multi-conductor sensor cable and an electrical interconnect configured to connect individual conductors of the multi-conductor sensor cable to individual sensors of the first and second plurality of sensors.

Particular embodiments disclosed herein provide one or more of the following advantages. The vehicle sensor mounting system provides stable and level mounting platforms for multiple rooftop sensors, including multiple cameras, RADAR sensors and a centrally mounted LiDAR sensor. The mechanical structures of the vehicle sensor mounting system are designed to mount the sensors to within a specified mechanical tolerance to reduce misalignment errors introduced into a sensor data “fusion” process performed by vehicle computer. The structures have a minimum natural frequency to reduce the impact of road vibration on the sensors. The structures are designed to avoid damage to the vehicle rooftop and to ensure that the rooftop and the structures do not occlude the FOVs of the sensors.

The details of the disclosed embodiments are set forth in the accompanying drawings and the description below. Other features, objects and advantages are apparent from the description, drawings and claims.

The same reference symbol used in various drawings indicates like elements.

DETAILED DESCRIPTION

In the drawings, specific arrangements or orderings of schematic elements, such as those representing devices, modules, instruction blocks and data elements, are shown for ease of description. However, it should be understood by those skilled in the art that the specific ordering or arrangement of the schematic elements in the drawings is not meant to imply that a particular order or sequence of processing, or separation of processes, is required. Further, the inclusion of a schematic element in a drawing is not meant to imply that such element is required in all embodiments or that the features represented by such element may not be included in or combined with other elements in some embodiments.

Several features are described hereafter that can each be used independently of one another or with any combination of other features. However, any individual feature may not address any of the problems discussed above or might only address one of the problems discussed above. Some of the problems discussed above might not be fully addressed by any of the features described herein. Although headings are provided, information related to a particular heading, but not found in the section having that heading, may also be found elsewhere in this description.

As used herein, the term “autonomous capability” refers to a function, feature, or facility that enables a vehicle to be partially or fully operated without real-time human intervention, including without limitation fully autonomous vehicles, highly autonomous vehicles, and conditionally autonomous vehicles.

As used herein, an autonomous vehicle (AV) is a vehicle that possesses autonomous capability.

As used herein, “vehicle” includes means of transportation of goods or people. For example, cars, buses, trains, airplanes, drones, trucks, boats, ships, submersibles, dirigibles, etc. A driverless car is an example of a vehicle.

As used herein, “trajectory” refers to a path or route to operate an AV from a first spatiotemporal location to second spatiotemporal location. In an embodiment, the first spatiotemporal location is referred to as the initial or starting location and the second spatiotemporal location is referred to as the destination, final location, goal, goal position, or goal location. In some examples, a trajectory is made up of one or more segments (e.g., sections of road) and each segment is made up of one or more blocks (e.g., portions of a lane or intersection). In an embodiment, the spatiotemporal locations correspond to real world locations. For example, the spatiotemporal locations are pick up or drop-off locations to pick up or drop-off persons or goods.

As used herein, “sensor(s)” includes one or more hardware components that detect information about the environment surrounding the sensor. Some of the hardware components can include sensing components (e.g., image sensors, biometric sensors), transmitting and/or receiving components (e.g., laser or radio frequency wave transmitters and receivers), electronic components such as analog-to-digital converters, a data storage device (such as a RAM and/or a nonvolatile storage), software or firmware components and data processing components such as an ASIC (application-specific integrated circuit), a microprocessor and/or a microcontroller.

As used herein, the phrase “one or more” includes a function being performed by one element, a function being performed by more than one element, e.g., in a distributed fashion, several functions being performed by one element, several functions being performed by several elements, or any combination of the above.

As used herein, an AV system refers to the AV along with the array of hardware, software, stored data, and data generated in real-time that supports the operation of the AV. In an embodiment, the AV system is incorporated within the AV. In an embodiment, the AV system is spread across several locations. For example, some of the software of the AV system is implemented on a cloud computing environment.

In general, this document describes technologies applicable to any vehicles that have one or more autonomous capabilities including fully autonomous vehicles, highly autonomous vehicles, and conditionally autonomous vehicles, such as so-called Level 5, Level 4 and Level 3 vehicles, respectively (see SAE International's standard J3016: Taxonomy and Definitions for Terms Related to On-Road Motor Vehicle Automated Driving Systems, which is incorporated by reference in its entirety, for more details on the classification of levels of autonomy in vehicles). The technologies described in this document are also applicable to partially autonomous vehicles and driver assisted vehicles, such as so-called Level 2 and Level 1 vehicles (see SAE International's standard J3016: Taxonomy and Definitions for Terms Related to On-Road Motor Vehicle Automated Driving Systems). In an embodiment, one or more of the Level 1, 2, 3, 4 and 5 vehicle systems may automate certain vehicle operations (e.g., steering, braking, and using maps) under certain operating conditions based on processing of sensor inputs. The technologies described in this document can benefit vehicles in any levels, ranging from fully autonomous vehicles to human-operated vehicles.

System Overview

FIG. 1is a perspective view of front assembly100of a vehicle sensor mounting system with sensors, according to an embodiment. Front assembly100includes bridge subassembly101, mounting brackets102a,102b,LiDAR103, forward facing cameras104a-104c,backward facing camera105, rear corner cameras106a,106band RADAR sensors107a,107b.LiDAR103is shown mounted on heat sink108. Front assembly100is shown mounted to existing anchor points (e.g., raised side rails, rain gutters) of a vehicle rooftop. Cameras104a-104c,105,106a,106band RADAR sensors107a,107bare each fixedly attached (attached by bolts) to sensor mounting platforms of bridge subassembly101, such that forward facing cameras104a-104cand backward facing camera105are substantially co-axial with LiDAR103.

In an embodiment, forward facing cameras104a-104chave their boresights physically aligned to with a specified mechanical tolerance so as to ensure their respective field-of-views (FOVs) cover a desired coverage area (e.g., approximately 15 degrees of overlap on forward facing cameras104a-104c). Rear corner cameras106a,106bhave their boresights directed toward the right-rear and left-rear corners of the vehicle, respectively. RADAR sensors107a,107bhave their transmitters directed to the right and left sides of the vehicle, respectively. Forward facing cameras104a-104care placed at locations on bridge subassembly101so as to minimize the physical distance between forward facing cameras104a-104cto minimize parallax.

In an embodiment, bridge subassembly101is a tubular bridge structure with two legs and a middle section attached to the two legs for mounting LiDAR103and cameras104a-104c,105. Bridge subassembly101is mounted across the width of the vehicle rooftop. The base of bridge subassembly101(near mounting brackets102a,102b) is wider than the middle section, and the legs curve behind the middle section to avoid occlusion of forward facing cameras104a-104cand LiDAR103by the vehicle and bridge subassembly101. The ends of the right and left legs of bridge subassembly101insert into sleeves of mounting brackets102a,102b.In an embodiment, mountain brackets102a,102bare configured to mount to existing anchor points on the vehicle rooftop to ensure high stiffness and strength, such as factory installed raised side rails, flat tracks, fix points or rain gutters. For a “bare” roof, a clip kit can be used that includes pads and clips that fasten to the outer edges of the roof by clamping around door jams. An advantage of these attachment methods is that bridge subassembly101can be mounted to the vehicle rooftop without drilling holes in the rooftop, which could damage the integrity of the rooftop.

In an embodiment, bridge subassembly101comprises multiple plates that when mated together form the tubular bridge structure. The bridge subassembly101has a minimum natural frequency target (e.g., 40 Hz) to reduce the impact of road vibrations. In an embodiment, bridge subassembly101is comprised of sheet metal, which provides acceptable mechanical tolerances using computer numerically controlled (CNC) cut and bending processes. Sheet metal can also easily integrate PEM® brand fasteners and other geometric features as needed. Bridge subassembly101is designed to remain attached to the rooftop in a 50 g crash. In an embodiment, mounting accuracy of bridge subassembly101is about 5 mm (with locational repeatability) and about 0.5 degree, roll, pitch and yaw.

Note that bridge subassembly101is an example embodiment. Other embodiments can have more or fewer sensors, and the sensors can be directed in different directions and located at different positions on bridge subassembly101other than the directions shown inFIG. 1.

FIG. 2is a bottom view of the front assembly100shown inFIG. 1, according to an embodiment. In an embodiment, a cooling fan is included inside bridge subassembly101(not shown) directly under LiDAR103. The cooling fan is used to draw heat from LiDAR103. In an embodiment, the air flow caused by the cooling fan is drawn from the bottom of bridge subassembly101to the top of bridge subassembly101and vent200is an air intake vent. In another embodiment, air flow is in the opposite direction and vent200operates as a heat exhaust vent.

FIG. 3is a perspective view of the front assembly300shown inFIG. 1with a cover attached, according to an embodiment. The cover includes top cover300aand bottom cover300b.In an embodiment, top cover300ais made of thermoplastic and includes sections301a,301bfor covering mounting brackets102a,102b,respectively, top right cover302a,top left cover302b,LiDAR cover304and bezel coupling305. When the top right/left covers302a,302bare attached to bottom cover300b(e.g., attached by snap fits), portals are formed for forward cameras104a-104c,backward facing camera105and rear corner cameras106a,106b.In an embodiment, bottom cover300bis also made of thermoplastic and designed to be mounted to the bottom of bridge subassembly101and installed on the vehicle. Bezel coupling305allows the LiDAR103to be removed and replaced with a LiDAR having a different diameter. For example, a bezel coupling305with a smaller or adaptable diameter can be used to couple a LiDAR with a smaller diameter than LiDAR103.

FIG. 4is a perspective view of bridge subassembly101shown inFIG. 1without the sensors or mounting brackets, according to an embodiment. Bridge subassembly101is a tubular bridge structure with two legs connected to a middle section. Bend angles at the intersections of the legs and middle section form a “bridge” profile. In an embodiment, the legs and middle section are comprised of multiple plates of sheet metal that are mated together, as described more fully in reference toFIG. 5.

FIG. 5is an exploded view of bridge subassembly101shown inFIG. 4. When the four sections shown inFIG. 5are mated together they form bridge subassembly101shown inFIG. 4. Bridge subassembly101includes bottom plate500, top right plate504, top left plate505, center plate506, right side plate507and left side plate508. Note that the terms “left” and “right” are from the perspective of a passenger facing the front of the vehicle. In an embodiment, bottom plate500includes three sections501-503fabricated from a single, continuous piece of sheet metal that provides a common datum for the other parts of bridge assembly101. Bottom plate section501includes side flange walls501a,501b,bottom plate section502includes side flange walls502a,502b,and bottom plate section503includes side flange walls503a,503b.Triangular notches509a-509dfacilitate the making of bend angles400a,400b(seeFIGS. 4 and 6).

As shown inFIG. 4, when the parts are mated the side flange walls504a,504bof top right plate504overlap the side flange walls501a,501bof bottom plate section501, resulting in a first leg of bridge subassembly101, as shown inFIG. 7. Similarly, the side flange walls505a,505bof top left plate505overlap the side flange walls503a,503bof bottom plate section503, resulting in the second leg of bridge subassembly101.

Center plate506providing the middle section of the tubular bridge structure and includes side flange walls506a,506bwhich overlap side flange walls502a,502bof bottom plate section502when in the mated configuration to form the middle section of bridge assembly101shown inFIG. 4. Additionally, top right plate504and top left plate505include center plate tabs504d1,504d2and505d1,505d2, respectively. The center plate tabs504d1,504d2,505d1,505d2overlap side flange walls506a,506b,respectively of center plate106when in the mated configuration shown inFIG. 4.

In the mated configuration, bend angles400a,400bare formed as shown inFIGS. 4 and 6. Bend angles400a,400bcreate the “bridge” profile with center plate506in the middle of the bridge to provide a level platform for LiDAR103. Bend angles400a,400ballow bridge subassembly101to suspend above the vehicle roof to prevent damage to the rooftop. Alignment holes in in bottom plate500, top right plate504, top left plate505and center plate506allow for the accurate alignment during assembly of bottom plate500with top right plate504, top left plate505and center plate506, before the parts are fastened together at rivet and/or bolt locations.

Right side plate507includes tabs507a,507bwith holes that facilitate mounting to “u-shaped” bracket501dattached to tabs501c1,501c2, using any suitable fastener (e.g., rivets, PEM® brand fasteners, bolts). Left side plate508includes tabs508a,508bwith holes that facilitate mounting to “u-shaped” bracket503dattached to tabs503c1,503c2, using any suitable fastener (e.g., rivets, PEM® brand fasteners, bolts).

Additional notches510a-510dbetween tabs501c1,501c2and side flange walls501a,501b,and tabs503c1,503c2and side flange walls503a,503b,respectively, facilitate bend angles at the right and left sides of bottom plate500so that the ends of bridge subassembly101are substantially level with the plane of the vehicle rooftop to facilitate their insertion into sleeves of mounting brackets102a,102b.

Tabs504c1,504c2of top right plate504facilitate the mounting of RADAR sensor107ato bridge subassembly101, and tabs505c1,505c2of top left plate505facilitate the mounting or RADAR sensor107bto bridge subassembly101.

The bridge subassembly101when mounted to the vehicle will be excited by high amplitude broad spectrum road vibrations encountered during normal use such a pot holes or cobblestone roads which generally occur at 30-40 hz. By raising the natural frequency of the bridge subassembly101above a 40 Hz minimum target the amplitude of the impulses to the sensors can be minimized, which allows the sensors to remain on a stable mounting and minimize the motion relative to the vehicle chassis. Additionally, the first modal shape of the vibration of bridge subassembly101is a combination of torsional or twisting motion and bending motion due to the overhanging mass and the way that the legs move rearward from the center of the structure to avoid occlusion. To reduce torsion and bending, bridge subassembly101is wider at its base (closer to the mounting brackets102a,102b) than at its center, increasing the second moment of the area for both torsion and bending. In an embodiment, a triangular brace runs through the middle section of the tubular bridge section which stiffens the top and bottom plates, minimizing deflection and raising the natural frequency of the bridge subassembly101.

FIG. 6is a close-up view of bend angle400bshown inFIG. 4, according to an embodiment. Center plate tab505d1attached to side flange wall505aof top left plate505overlaps side flange wall506aof center plate506and is welded and riveted to side flange wall506a.

FIG. 7is a left side view of the bridge subassembly101showing the tubular construction, according to an embodiment. Side flange walls505a,505bof top left plate505overlap side flange walls503a,503bof bottom plate section503and are welded together at welding points.

FIG. 8is a perspective view of rear assembly800of the vehicle sensor mounting system, according to an embodiment. Rear assembly800is mounted on the roof top of the vehicle with front assembly100, and collectively comprise the vehicle sensor mounting system. Rear assembly800is located toward the rear of the vehicle and is attached to existing rooftop anchor points (e.g., rails, rain gutters) of the vehicle using mounting blocks806a,806b.

Rear assembly800includes bridge subassembly801that includes two legs and a middle section similar to bridge subassembly101. In an embodiment, bridge subassembly is made of aluminum. Bridge subassembly800includes five disconnected plates. Each leg is comprised of two plates and the middle section includes a single plate. The plate for the middle section provides a level mounting platform for center backward camera802band dedicated short range communication (DSRC) antenna804. The plates for the legs provide platforms for Global Position System (GPS) antennas803a-803f.Mounting blocks806a,806bprovide mounting platforms for rear corner cameras802a,802c.Underneath the middle section plate is cable hub assembly805, which is described more fully in reference toFIG. 10.

Note that bridge subassembly800is an example embodiment. Other embodiments can have more or fewer sensors, and the sensors can be directed in different directions and located at different positions on bridge subassembly800other than the directions shown inFIG. 8.

FIG. 9shows the rear assembly with its cover attached, according to an embodiment. Like front assembly100, rear assembly800has top cover900aand bottom cover900b.Bottom cover900bis attached to bridge subassembly801(e.g., using machine screws) and mounted to the vehicle rooftop. Top cover900includes multiple sections that can be removed for service access without removing the entire rear assembly800from the vehicle rooftop.

FIG. 10is a perspective of the cable hub assembly805shown inFIG. 8, according to an embodiment. Cable hub assembly805is positioned over an existing opening in the vehicle rooftop (used for rooftop antenna found on most modern cars) and provides a single point of ingress/egress for a multi-conductor sensor cable for communicating sensor data from the rooftop sensors. Cable hub assembly805mounts underneath bridge assembly801using four mounting posts1004a-1104dand machine screws. Gasket1002provides a water-resistance seal around the multiconductor cable. Interface1001(e.g., a PH2.0-5P interface) provides power and a data communication path for LiDAR103. Interface1001can also include power circuitry, such as transformers, inverters, filters and voltage regulators. Interconnect1003provides an electrical interconnect for the individual conductors of the multi-conductor sensor cable (not shown) in the vehicle sensor cable (not shown) to be attached to the individual rooftop sensors.

In the foregoing description, embodiments of the invention have been described with reference to numerous specific details that may vary from implementation to implementation. The description and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense. The sole and exclusive indicator of the scope of the invention, and what is intended by the applicants to be the scope of the invention, is the literal and equivalent scope of the set of claims that issue from this application, in the specific form in which such claims issue, including any subsequent correction. Any definitions expressly set forth herein for terms contained in such claims shall govern the meaning of such terms as used in the claims. In addition, when we use the term “further including,” in the foregoing description or following claims, what follows this phrase can be an additional step or entity, or a sub-step/sub-entity of a previously-recited step or entity.