LANE CHANGE NEGOTIATION METHODS AND SYSTEMS

In various embodiments, methods, systems, and vehicles are provided for executing a lane change for a host vehicle. In various embodiments, a method includes: receiving, by a processor, an indication that a lane change from an initial lane to an intended lane is desired for the host vehicle; defining, by the processor, an initial lane center target, a negotiation target, and an intended lane center target based on the desired lane change; and controlling, by the processor, the host vehicle to at least one of the initial lane center target, the negotiation target, and the intended lane center target based on a finite state machine, wherein the initial lane center target is at or in proximity to a determined center of the initial lane, wherein the intended lane center target is at or in proximity to a determined center of the intended lane, and wherein the negotiation target is offset from the initial lane center target and within the initial lane.

TECHNICAL FIELD

The present disclosure generally relates to vehicles, and more particularly relates to systems and methods for negotiating a lane change for an autonomous vehicle.

An autonomous vehicle is a vehicle that is capable of sensing its environment and navigating with little or no user input. It does so by using sensing devices such as radar, lidar, image sensors, and the like. Autonomous vehicles further use information from global positioning systems (GPS) technology, navigation systems, vehicle-to-vehicle communication, vehicle-to-infrastructure technology, and/or drive-by-wire systems to navigate the vehicle.

While autonomous vehicles offer many potential advantages over traditional vehicles, in certain circumstances it may be desirable for improved movement of autonomous vehicles. For example, autonomous vehicles perform lane changes to navigate to a next turn, to exit a highway, maneuver around other vehicles or object in the lane, or to increase speed. When the adjacent lane is heavily trafficked, the vehicle must “cut-in” to the adjacent lane, in between other vehicles. Accordingly, it is desirable to provide systems and methods for negotiating a lane change with the other vehicles before performing the cut-in lane change maneuver. Furthermore, other desirable features and characteristics of the present disclosure will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.

SUMMARY

In various embodiments, methods, systems, and vehicles are provided for executing a lane change for a host vehicle. In various embodiments, a method includes: receiving, by a processor, an indication that a lane change from an initial lane to an intended lane is desired for the host vehicle; defining, by the processor, an initial lane center target, a negotiation target, and an intended lane center target based on the desired lane change; and controlling, by the processor, the host vehicle to at least one of the initial lane center target, the negotiation target, and the intended lane center target based on a finite state machine, wherein the initial lane center target is at or in proximity to a determined center of the initial lane, wherein the intended lane center target is at or in proximity to a determined center of the intended lane, and wherein the negotiation target is offset from the initial lane center target and within the initial lane.

In various embodiments, the determining the negotiation target is based on sensor data received from sensors of the host vehicle.

In various embodiments, the determining the negotiation target is based on vehicle parameters defining the size of the host vehicle.

In various embodiments, the determining the negotiation target is based on a desired right lane change and a desired left lane change.

In various embodiments, the finite state machine includes at least three states, an initial lane centering state, a negotiation state, and an intended lane centering state, and wherein the method comprises: controlling, by the processor, the host vehicle to the initial lane center target when a current state is the initial lane centering state; controlling, by the processor, the host vehicle to the negotiation target when the current state is the negotiation state; and controlling, by the processor, the host vehicle to the intended lance center target when the current state is the intended lane centering state.

In various embodiments, the finite state machine includes a plurality of transitions, wherein at least one of the transitions is based on a safety distance associated with an other.

In various embodiments, the method includes determining the other vehicle to be within the initial lane and ahead of a position of the host vehicle.

In various embodiments, the method includes determining the other vehicle to be within the intended lane behind or at a position of the host vehicle.

In various embodiments, the method includes determining the other vehicle to be within the intended lane and ahead of a position of the host vehicle.

In various embodiments, the method includes computing the safety distance based on a predicted state of the other vehicle at a future time.

In various embodiments, the method includes computing the safety distance based on the predicted state of the other vehicle at the future time and until the future time is equal to a predicted time of cut-in to the intended lane.

In various embodiments, the method includes computing the safety distance based on a predicted time of cut-in to the intended lane, a predicted state of the host vehicle at the predicted time of cut-in, and a predicted state of the other vehicle at the predicted time of cut-in.

In another embodiment, a system for executing a lane change for a host vehicle includes: one or more sensors configured to obtain sensor data pertaining to a host vehicle and one or more other vehicles in proximity to the host vehicle; and a processor coupled to the one or more sensors. The processor is configured to: receive an indication that a lane change from an initial lane to an intended lane is desired for the host vehicle; define an initial lane center target, a negotiation target, and an intended lane center target based on the desired lane change; and control the host vehicle to at least one of the initial lane center target, the negotiation target, and the intended lane center target based on a finite state machine, wherein the initial lane center target is at or in proximity to a determined center of the initial lane, wherein the intended lane center target is at or in proximity to a determined center of the intended lane, and wherein the negotiation target is offset from the initial lane center target and within the initial lane.

In various embodiments, the negotiation target is determined based on at least one of the sensor data, vehicle parameters defining the size of the host vehicle, a desired right lane change and a desired left lane change.

In various embodiments, the finite state machine includes at least three states, an initial lane centering state, a negotiation state, and an intended lane centering state, and wherein when a current state is the initial lane centering state, the processor controls the host vehicle to the initial lane center target, wherein when the current state is the negotiation state, the processor controls the host vehicle to the negotiation target, and when the current state is the intended lane centering state, the processor controls the host vehicle to the intended lance center target.

In various embodiments, the finite state machine includes a plurality of transitions, wherein at least one of the transitions is based on a safety distance associated with an other.

In various embodiments, the processor is further configured to: compute the safety distance based on a predicted state of the other vehicle at a future time.

In various embodiments, the processor is further configured to: compute the safety distance based on the predicted state of the other vehicle at the future time and until the future time is equal to a predicted time of cut-in to the intended lane.

In various embodiments, the processor is further configured to: compute the safety distance based on a predicted time of cut-in to the intended lane, a predicted state of the host vehicle at the predicted time of cut-in, and a predicted state of the other vehicle at the predicted time of cut-in.

In yet another embodiment, an autonomous vehicle includes: one or more sensors configured to obtain sensor data pertaining to the autonomous vehicle and one or more other vehicles in proximity to the autonomous vehicle; and a processor coupled to the one or more sensors. The processor is configured to: receive an indication that a lane change from an initial lane to an intended lane is desired for the autonomous vehicle; define an initial lane center target, a negotiation target, and an intended lane center target based on the desired lane change; and control the autonomous vehicle to at least one of the initial lane center target, the negotiation target, and the intended lane center target based on a finite state machine, wherein the initial lane center target is at or in proximity to a determined center of the initial lane, wherein the intended lane center target is at or in proximity to a determined center of the intended lane, and wherein the negotiation target is offset from the initial lane center target and within the initial lane.

DETAILED DESCRIPTION

The following detailed description is merely exemplary in nature and is not intended to limit the application and uses. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary, or the following detailed description. As used herein, the term “module” refers to any hardware, software, firmware, electronic control component, processing logic, and/or processor device, individually or in any combination, including without limitation: application specific integrated circuit (ASIC), a field-programmable gate-array (FPGA), an electronic circuit, a processor (shared, dedicated, or group) and memory that executes one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality.

With reference toFIG.1, a lane change negotiation system shown generally as100is associated with a vehicle10(also referred to herein as a “host vehicle”) in accordance with various embodiments. In general, the lane change negotiation system (or simply “system”)100provides for negotiation by the host vehicle of a lane change in front of a vehicle or between vehicles travelling in an adjacent lane. For example, in various embodiments, the vehicle10negotiates the lane change by travelling first at a lateral location that is offset from the lane center and then performing the lane change when it is determined safe to perform a cut-in maneuver. The vehicle determines when it is safe based on a proactive analysis of the vehicles in the current lane and the intended lane.

As depicted inFIG.1, the vehicle10generally includes a chassis12, a body14, front wheels16, and rear wheels18. The body14is arranged on the chassis12and substantially encloses components of the vehicle10. The body14and the chassis12may jointly form a frame. The wheels16-18are each rotationally coupled to the chassis12near a respective corner of the body14. In various embodiments, the wheels16,18comprise a wheel assembly that also includes respective associated tires.

In various embodiments, the vehicle10is an autonomous vehicle, and the lane change planning system100, and/or components thereof, are incorporated into the vehicle10. The vehicle10is, for example, a vehicle that is automatically controlled to carry passengers from one location to another. The vehicle10is depicted in the illustrated embodiment as a passenger car, but it should be appreciated that any other vehicle, including motorcycles, trucks, sport utility vehicles (SUVs), recreational vehicles (RVs), marine vessels, aircraft, and the like, can also be used.

In an exemplary embodiment, the vehicle10corresponds to a level two, level three, level four, or level five automation system under the Society of Automotive Engineers (SAE) “J3016” standard taxonomy of automated driving levels. Using this terminology, a level four system indicates “high automation,” referring to a driving mode in which the automated driving system performs all aspects of the dynamic driving task, even if a human driver does not respond appropriately to a request to intervene. A level five system, on the other hand, indicates “full automation,” referring to a driving mode in which the automated driving system performs all aspects of the dynamic driving task under all roadway and environmental conditions that can be managed by a human driver. It will be appreciated, however, the embodiments in accordance with the present subject matter are not limited to any particular taxonomy or rubric of automation categories. Furthermore, systems in accordance with the present embodiment may be used in conjunction with any autonomous, non-autonomous, or other vehicle that includes sensors and a suspension system.

As shown, the vehicle10generally includes a propulsion system20, a transmission system22, a steering system24, a brake system26, one or more user input devices27, a sensor system28, an actuator system30, at least one data storage device32, at least one controller34, and a communication system36. The propulsion system20may, in various embodiments, include an internal combustion engine, an electric machine such as a traction motor, and/or a fuel cell propulsion system. The transmission system22is configured to transmit power from the propulsion system20to the vehicle wheels16and18according to selectable speed ratios. According to various embodiments, the transmission system22may include a step-ratio automatic transmission, a continuously-variable transmission, or other appropriate transmission.

The brake system26is configured to provide braking torque to the vehicle wheels16and18. Brake system26may, in various embodiments, include friction brakes, brake by wire, a regenerative braking system such as an electric machine, and/or other appropriate braking systems. The steering system24influences a position of the vehicle wheels16and/or18. While depicted as including a steering wheel for illustrative purposes, in some embodiments contemplated within the scope of the present disclosure, the steering system24may not include a steering wheel.

The sensor system28includes one or more sensors40a-40nthat sense observable conditions of the exterior environment and/or the interior environment of the vehicle10. The sensors40a-40ninclude, but are not limited to, radars, lidars, global positioning systems, optical cameras, thermal cameras, ultrasonic sensors, inertial measurement units, and/or other sensors.

The actuator system30includes one or more actuators42a-42nthat control one or more vehicle features such as, but not limited to, the propulsion system20, the transmission system22, the steering system24, and the brake system26. In various embodiments, vehicle10may also include interior and/or exterior vehicle features not illustrated inFIG.1, such as various doors, a trunk, and cabin features such as air, music, lighting, touch-screen display components (such as those used in connection with navigation systems), and the like.

The data storage device32stores data for use in automatically controlling the vehicle10. In various embodiments, the data storage device32stores defined maps of the navigable environment. In various embodiments, the defined maps may be predefined by and obtained from a remote system. For example, the defined maps may be assembled by the remote system and communicated to the vehicle10(wirelessly and/or in a wired manner) and stored in the data storage device32. Route information may also be stored within data storage device32—i.e., a set of road segments (associated geographically with one or more of the defined maps) that together define a route that the user may take to travel from a start location (e.g., the user's current location) to a target location. As will be appreciated, the data storage device32may be part of the controller34, separate from the controller34, or part of the controller34and part of a separate system.

In certain embodiments, the communication system36is further configured for communication between the sensor system28, the actuator system30, one or more controllers (e.g., the controller34), and/or more other systems and/or devices. For example, the communication system36may include any combination of a controller area network (CAN) bus and/or direct wiring between the sensor system28, the actuator system30, one or more controllers34, and/or one or more other systems and/or devices. In various embodiments, the communication system36may include one or more transceivers for communicating with one or more devices and/or systems of the vehicle10, devices of the passengers, and/or one or more sources of remote information (e.g., GPS data, traffic information, weather information, and so on).

In various embodiments, the controller34includes one or more components of the lane change negotiation system100. For example, one or more instructions of the controller, when executed by the processor44, execute logic of a finite state machine to control the vehicle during a lane change maneuver according to defined lateral targets and safety measures. As can be appreciated, the subject matter disclosed herein provides certain enhanced features and functionality to what may be considered as a standard or baseline vehicle10and/or a vehicle based remote transportation system associated with the vehicle10. To this end, a vehicle and vehicle based remote transportation system can be modified, enhanced, or otherwise supplemented to provide the additional features described in more detail below.

With reference now toFIG.2, in accordance with various embodiments, the controller34implements an autonomous driving system (ADS). That is, suitable software and/or hardware components of the controller34(e.g., processor44and computer-readable storage device46) are utilized to provide an ADS that is used in conjunction with vehicle10.

In various embodiments, the instructions of the autonomous driving system70may be organized by function or system. For example, as shown inFIG.2, the autonomous driving system70can include a computer vision system74, a positioning system76, a guidance system78, and a vehicle control system80. As can be appreciated, in various embodiments, the instructions may be organized into any number of systems (e.g., combined, further partitioned, and the like) as the disclosure is not limited to the present examples.

In various embodiments, the computer vision system74synthesizes and processes sensor data and predicts the presence, location, classification, and/or path of objects and features of the environment of the vehicle10. In various embodiments, the computer vision system74can incorporate information from multiple sensors, including but not limited to cameras, lidars, radars, and/or any number of other types of sensors.

The positioning system76processes sensor data along with other data to determine a position (e.g., a local position relative to a map, an exact position relative to lane of a road, vehicle heading, velocity, etc.) of the vehicle10relative to the environment. The guidance system78processes sensor data along with other data to determine a path for the vehicle10to follow. The vehicle control system80generates control signals for controlling the vehicle10according to the determined path.

In various embodiments, the controller34implements machine learning techniques to assist the functionality of the controller34, such as feature detection/classification, obstruction mitigation, route traversal, mapping, sensor integration, ground-truth determination, and the like.

In various embodiments, as discussed above with regard toFIG.1, one or more instructions of the controller34are embodied in the lane change negotiation system100, for planning lateral targets and control the movement of the vehicle10during left or right lane change maneuvers. All or parts of the lane change negotiation system100may be embodied in the guidance system78, and/or the vehicle control system80or may be implemented as a separate system, as shown.

As shown inFIGS.3A and3B, the lane change negotiation system100includes at least three lateral targets for each lane change direction. In various embodiments, the lateral targets can be determined based on sensor data received from the sensor system of the vehicle10, map data, and/or parameters indicating a size of the vehicle10. As shown inFIG.3A, for a lane change to the right from an initial lane102to an intended lane104, the lateral targets include: a center of initial lane target106, a negotiation target108which is offset to the right of the center of the initial lane102, and a center of intended lane target110. In another example, as shown inFIG.3B, for a lane change to the left from the initial lane102to the intended lane104, the lateral targets include: the center of initial lane target106, a negotiation target112which is offset to the left or right of the center of the initial lane102, and a center of intended lane target110. In various embodiments, it is assumed that travelling on the negotiation offsets108,112(and/or moving towards the negotiation offsets108,112) signals to other drivers about an intended cut-in maneuver and creates a reaction of the other drivers in the corresponding intended lane104.

In various embodiments, the vehicle10is controlled laterally to any one of the targets106,108,110,112at any time, based on logic of a finite state machine. As shown inFIG.4, an exemplary finite state machine120includes at least three states122-126and a plurality of transitions130-140. In various embodiments, the states include an initial lane centering state122, a negotiation state124, and an intended lane centering state126. When in the initial lane centering state122, the vehicle10is controlled to the center of initial lane target106. When in the negotiation state124, the vehicle10is controlled to the negotiation target108,112that is in the direction of the lane change. When in the intended lane centering state126, the vehicle10is controlled to the center of the intended lane target110.

Transitioning from the initial lane centering state122to the negotiation state124at transition130and staying in the negotiation state124at transition132is assumed to trigger a reaction of other drivers in the intended lane104(e.g., yield, slow-down with some probability, etc.). The vehicle10can be controlled to stay in the negotiation state124for an unlimited time. The vehicle10transitions from the negotiation state124back to the initial lane centering state122at transition134can occur when it is determined that the lane change is no longer desired (e.g., change in route planning according to human driver feedback or any external feedback to the system). This transition can be referred to as “aborting” the lane change. Transitioning from the negotiation state124to the intended lane centering state126occurs at transition136when it is determined that the vehicle10can commit to execute the lane change to completion safely. Once the intended lane centering state126is active and a complete lane change has been fully executed with the vehicle10at the center of the intended lane target110, the vehicle10is transitioned back to the initial lane centering state122at138. The vehicle10is maintained in the initial lane centering state122at transition140until a lane change is desired again.

In various embodiments, while in the initial lane centering state122, transitioning to the negotiation state124, and in the negotiation state124, safety is maintained with respect to other vehicles in the initial lane104since the vehicle10still lies in the initial lane104and does not interfere with traffic in the target lane. For example, as shown inFIG.5, future lateral motion plans of the vehicle10are validated by computing a safety distance150with respect to a leading vehicle152in the initial lane102. The vehicle10is controlled to perform the lateral movement prior to the computed safety distance150. In various embodiments, the safety distance is computed based on a summation of the vehicle10distance travelled before reacting, and the vehicle10distance travelled while acting (braking), minus the vehicle152distance travelled while braking. In various embodiments, the distances are based on velocities of the respective vehicles.

As discussed above, transitioning from the negotiation state124to the intended lane centering state126at transition136is allowed only when the lane change can be verified for safety until completion. The verification is performed ahead of execution of the lane change and requires taking more pro-active measures.

For example, as shown inFIG.6, safety is maintained with respect to three possible vehicles. The vehicles include a vehicle154in the intended lane104in which the vehicle10intends to cut-in in front of, a vehicle156in the intended lane104in which the vehicle10intends to cut-in in back of, and the vehicle152in the initial lane102in which the vehicle10is travelling behind. Future lateral motion plans of the vehicle10are validated by computing a safety distance150with respect to any detected vehicle of the three possible vehicles152,154, and156.

When evaluating safety against the vehicle154, a safety distance158is computed based on a predicted time when the cut-in should occur (t_cut), a predicted state of the vehicle10and a predicted state of the vehicle154at the expected time of cut-in (t_cut), with ro>0 to account for the time delay it takes the vehicle154to detect the cut-in. In various embodiments, the state of the vehicle154is predicted using a worst-case prediction model; and the state of the vehicle10is predicted using a sample from the future motion plan at t_cut. Note that this requires that the vehicle10will accurately follow the motion plan at least until time (t_cut) with no deviations. The vehicle10is controlled to perform the lateral movement after the computed safety distance158.

When evaluating safety against the vehicle152, a safety distance160is computed based on a predicted state at a future time (t+dt). Here, safety validations are performed from current time t up to time t+dt where dt stands for the time between planning-iterations. For instance, if planning is executed every one second, then dt=1 [sec]. In various embodiments, the state of the vehicle10is predicted using a sample from the future motion plan at times in the range t to t+dt. Thereafter, the vehicle10is controlled to perform the lateral movement prior to the computed safety distance160.

When evaluating safety against the vehicle156, a safety distance162is similarly computed based on a predicted state at a maximum of the future time and the predicted time to cut-in mas(t+dt, t_cut) to facilitate the requirement above of tracking the motion plan accurately at least until t_cut. The vehicle10is controlled to perform the lateral movement prior to the computed safety distance162.

To allow the vehicle10to safely react to changes in the states of vehicles152and156while in the intended lane centering state, the last two conditions are tested according to detected lane-occupancy of the vehicle10. In various embodiments, the availability of the lane change maneuver depends on the time to cut-in (t_cut−t). By setting the negotiation target close to the lane's boundary reduces the time to cut-in when evaluating lane change safety conditions and increases availability.

With reference toFIG.7and with continued reference toFIG.1-6, a flowchart is provided for a control process200for planning a lane change along a roadway. In accordance with various embodiments, the control process200can be implemented in connection with the lane change negotiation system100and vehicle10ofFIG.1, the autonomous driving system ofFIG.2, and the finite state machine ofFIG.4. As can be appreciated in light of the disclosure, the order of operation within the control process200is not limited to the sequential execution as illustrated inFIG.7but may be performed in one or more varying orders as applicable and in accordance with the present disclosure. In various embodiments, the control process200can be scheduled to run based on one or more predetermined events, and/or can run continuously during operation of the vehicle10.

In one example, the control process200may begin at205. The vehicle10is controlled to the initial lane center target106at210, Thereafter, it is determined whether a lane change is desired at220. When a lane change is not desired at220, the process200continues with controlling the vehicle10to the initial lane center target106at210.

When a lane change is desired at220, the vehicle10is controlled laterally to or near the negotiation target108or112at220. Thereafter, it is determined, while travelling at the negotiation offset108or112, whether the lane change is still desired at240. When the lane change is no longer desired at240, the process200continues with controlling the vehicle10to the initial lane center target106at210.

When a lane change is still desired at240, it is determined whether the full lane change is safe at250. When it is determined that the full lane change is not safe at250, the process200continues with controlling the vehicle10laterally to or near the negotiation target108or112at220. When it is determined that the full lane change is safe at250, the vehicle10is controlled laterally to the intended lane center target110at260. If the vehicle10is not yet assigned to the intended lane104at270, the process200continues with controlling the vehicle10laterally to the intended lane center target110at260. Once the vehicle10is assigned to the intended lane104, the process200continues with controlling the vehicle10laterally to the new initial lane center target106at210.