System and method for intervening a steering system at standstill

Abstract

A computer-implemented method that, when executed by computing hardware, causes the computing hardware to perform operations that include detecting a request to enable an automated driving system of a vehicle while the vehicle is at rest or traveling at a low speed, determining an intended path of the vehicle, determining an initial steering angle, calculating a desired steering angle based on the intended path, calculating a commanded steering angle, evaluating the initial steering angle against the desired steering angle, and either (i) initiating a driving maneuver with the initial steering angle or (ii) adjusting the steering angle based on the commanded steering angle prior to initiating the driving maneuver.

Description

The invention relates to a computer-implemented method. The present invention relates generally to a system and method for determining whether the steering system of a vehicle is required to engage at a standstill or at a low speed before a driving maneuver is initiated.The document DE 11 2020 001 409 T5 discloses a method for controlling the steering of a vehicle.The document DE 11 2020 001 530 T5 discloses a method for controlling the speed and the course of a vehicle.US 2009 / 0 037 062 A1 discloses a method for detecting a road curve when a vehicle approaches the curve, for automatically providing road curvature information and for controlling the vehicle speed.Vehicles are often equipped with automated driving systems that can be released while the vehicle is at rest (i.e., at rest) or is travelling at low speed. When enabling the automated driving system, the steering angle (i.e., road wheel angle) of the vehicle is often not aligned with the steering angle or does not correspond to the steering angle that would provide good track following with respect to an intended path exhibited by the automated driving system.It is an object of the invention to address the shortcomings of existing systems and methods.The solution of the aforementioned object is achieved by a computer-implemented method having the features of claim 1.One aspect of the invention provides a computer-implemented method that, when executed by data processing hardware, causes the data processing hardware to perform operations. These operations include detecting a request to enable an automated driving system of a vehicle while the vehicle is at rest or is traveling at a low speed, determining a designated path of the vehicle, determining an initial steering angle, calculating a target steering angle based on the designated path, calculating a commanded steering angle, evaluating the initial steering angle against the target steering angle, and either (i) initiating a driving maneuver with the initial steering angle or (ii) adjusting the steering angle based on the commanded steering angle prior to initiating the driving maneuver.For example, adjusting the steering angle may further include a vehicle steering system configured to adjust the initial steering angle prior to initiating the driving maneuver.According to some implementations, adjusting the steering angle prior to initiating the driving maneuver may include instructing an operator of the vehicle to manually adjust the initial steering angle based on the commanded steering angle prior to initiating the driving maneuver.The method further includes evaluating a tracking quality index. If the tracking quality index is between a first threshold and a second threshold, the driving maneuver may be initiated with the initial steering angle. If the tracking quality index is between a second threshold and a third threshold, a vehicle steering system configured to adjust the steering angle may adjust the steering angle based on the commanded steering angle before initiating the driving maneuver. If the tracking quality index is greater than a fourth threshold and less than a third threshold, a vehicle management system configured to instruct an operator of the vehicle may instruct the operator to manually adjust the steering angle based on the commanded steering angle before initiating the driving maneuver.According to at least one aspect, evaluating the tracking quality index may be a function of the predicted future vehicle conditions and the intended future trajectory.According to one example, evaluating the tracking quality index may further include evaluating the initial steering angle of the vehicle using a predictive controller and a vehicle model at low speeds.Another aspect of the invention provides a system comprising computing hardware and memory hardware associated with the computing hardware, the memory hardware storing instructions that, when executed on the computing hardware, cause the computing hardware to perform operations. These operations include detecting a request to enable an automated driving system of a vehicle while the vehicle is at rest or is traveling at a low speed, determining a designated path of the vehicle, determining an initial steering angle, calculating a target steering angle based on the designated path, calculating a commanded steering angle, evaluating the initial steering angle against the target steering angle, and either (i) initiating a driving maneuver with the initial steering angle or (ii) adjusting the steering angle based on the commanded steering angle prior to initiating the driving maneuver.The implementations of the invention may include one or more of the following optional features. For example, adjusting the steering angle may further include a vehicle steering system configured to adjust the initial steering angle prior to initiating the driving maneuver.According to some implementations, adjusting the steering angle prior to initiating the driving maneuver may include instructing an operator of the vehicle to manually adjust the initial steering angle based on the commanded steering angle prior to initiating the driving maneuver.According to some examples, the system may further include evaluating a tracking quality index. If the tracking quality index is between a first threshold and a second threshold, the driving maneuver may be initiated with the initial steering angle. If the tracking quality index is less than a second threshold and greater than or equal to a third threshold, a vehicle steering system configured to adjust the steering angle may adjust the steering angle based on the commanded steering angle before initiating the driving maneuver. If the tracking quality index is greater than a fourth threshold and less than a third threshold, a vehicle management system configured to instruct an operator of the vehicle may instruct the operator to manually adjust the steering angle based on the commanded steering angle before initiating the driving maneuver.An additional aspect of the invention provides a vehicle management system. The vehicle management system includes a steering system configured to adjust a steering angle of a vehicle, computing hardware, and memory hardware in communication with the computing hardware, the memory hardware storing instructions that, when executed on the computing hardware, cause the computing hardware to perform operations. These operations include detecting a request to enable an automated driving system of a vehicle while the vehicle is at rest or is traveling at a low speed, determining a designated path of the vehicle, determining an initial steering angle, calculating a target steering angle based on the designated path, calculating a commanded steering angle, evaluating the initial steering angle against the target steering angle, and either (i) initiating a driving maneuver with the initial steering angle or (ii) adjusting the steering angle prior to initiating the driving maneuver.The implementations of the invention may include one or more of the following optional features. Adjusting the steering angle prior to initiating the driving maneuver includes, for example, instructing an operator of the vehicle to manually adjust the initial steering angle based on the commanded steering angle prior to initiating the driving maneuver.According to some implementations, the vehicle management system further includes evaluating a tracking quality index. If the tracking quality index is between a first threshold and a second threshold, the driving maneuver may be initiated with the initial steering angle. If the tracking quality index is less than the second threshold and greater than or equal to a third threshold, a vehicle steering system configured to adjust the steering angle may adjust the steering angle based on the commanded steering angle before initiating the driving maneuver. If the tracking quality index is greater than a fourth threshold and less than the third threshold, a vehicle management system configured to instruct an operator of the vehicle may instruct the operator to manually adjust the steering angle based on the commanded steering angle before initiating the driving maneuver.The drawings described herein are for illustrative purposes only of selected configurations; it shows: FIG. 1 is a schematic diagram of a vehicle environment including a vehicle and a vehicle management system of the vehicle according to the principles of the present invention; FIG. 2A is an enlarged schematic diagram showing an example of the vehicle management system according to the principles of the present invention; FIG. 2B is an enlarged schematic diagram of a model predictive controller of FIG. 2A ; FIG. 3A is a top view of the vehicle of FIG. 1 on a road in accordance with the principles of the present invention; FIG. 3B is a top view of the vehicle of FIG. 1 on a road in accordance with the principles of the present invention; FIG. 3C is a top view of the vehicle of FIG. 1 on a road in accordance with the principles of the present invention; FIG. 3D is a top view of the vehicle of FIG. 1 at an intersection in accordance with the principles of the present invention; and FIG. 4 is a flow chart showing operations of the vehicle management system of FIG. 2A.Corresponding reference numerals designate corresponding parts throughout the drawings.Now, exemplary configurations will be described more fully with reference to the accompanying drawings. Specific details such as examples of specific components, devices, and methods are set forth in order to provide a thorough understanding of the configurations of the present invention. It will be apparent to those of ordinary skill in the art that specific details need not be used, that the exemplary embodiments of the configurations may be embodied in many different forms.The terminology used herein is for describing particular exemplary configurations only and is not intended to be limiting. The singular articles "a", "an" and "the / s" as used herein are also intended to include the plural forms unless the context clearly indicates otherwise. The terms "comprises," "comprising," "including," and "having" are inclusive and therefore specify the presence of features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring execution thereof in the particular order discussed or illustrated, unless specifically identified as an order of execution. Additional or alternative steps may be used.When an element or layer is referred to as being "on," "engaged to," "connected to," "attached to," or "coupled to" another element or layer, it may be directly on, engaged to, connected to, attached to, or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on," "directly engaged to," "directly connected to," "directly attached to," or "directly coupled to" another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like manner (e.g., "between" as opposed to "directly between," "adjacent" as opposed to "directly adjacent," etc.). As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.The terms "first," "second," "third," etc., may be used herein to describe various elements, components, regions, layers, and / or portions. These elements, components, regions, layers, and / or sections should not be limited by these terms. These terms may be used only to distinguish one element, component, region, layer, or portion from another region, layer, or portion. Terms such as "first," "second," and other numerical terms do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer, or portion discussed below could be referred to as a second element, component, region, layer, or portion without departing from the teachings of the example configurations.In this application, including the definitions below, the term "module" may be replaced by the term "circuit". The term "module" may refer to, be part of, or include an application specific integrated circuit (ASIC); a digital, analog, or mixed analog / digital discrete circuit; a digital, analog, or mixed analog / digital integrated circuit; a combinational logic circuit; a field programmable gate array (FPGA); a processor (shared, dedicated, or group) that executes code; a memory (shared, dedicated, or group) that stores code executed by a processor; other suitable hardware components that provide the described functionality; or a combination of some or all of the above, such as in a system on a chip.The term "code" as used above may include software, firmware, and / or microcode, and may refer to programs, routines, functions, classes, and / or objects. The term "shared processor" includes a single processor that executes some or all of the code from multiple modules. The term "group processor" includes a processor that, in combination with additional processors, executes some or all of the code from one or more modules. The term "shared memory" includes a single memory that stores some or all of the code from multiple modules. The term "group memory" includes a memory that, in combination with additional memories, stores some or all of the code from one or more modules. The term "memory" may be a subset of the term "computer readable medium.". The term "computer readable medium" does not include the transitory electrical and electromagnetic signals propagating through a medium and may therefore be considered a tangible and non-transitory memory. Non-limiting examples of non-transitory memory include a tangible computer readable medium including a non-transitory memory, a magnetic memory, and an optical memory.The apparatuses and methods described in this application may be partially or fully implemented by one or more computer programs executed by one or more processors. The computer programs include processor-executable instructions stored on at least one non-transitory tangible computer-readable medium. The computer programs may also include and / or rely on stored data.A software application (i.e., software resource) may refer to computer software that causes a computing device to execute a task. According to some examples, a software application may be referred to as an "application," an "app," or a "program.". Example applications include, but are not limited to, system diagnostic applications, system management applications, system maintenance applications, word processing applications, spreadsheet applications, messaging applications, media streaming applications, social network applications, and gaming applications.The non-transitory memory may include physical devices used to temporarily or permanently store programs (e.g., sequences of instructions) or data (e.g., program state information) for use by a computing device. The non-transitory memory may be a volatile and / or non-volatile addressable semiconductor memory. Examples of the non-volatile memory include, but are not limited to, flash memory and read only memory (ROM) / programmable read only memory (PROM) / erasable programmable read only memory (EPROM) / electronically erasable programmable read only memory (EEPROM) (e.g., typically used for firmware such as boot programs). Examples of volatile memory include, but are not limited to, random access memory (RAM), dynamic random access memory (DRAM), static random access memory (SRAM), phase change memory (PCM), as well as disks or tapes.These computer programs (also known as programs, software, software applications, or code) contain machine instructions for a programmable processor and may be implemented in procedural and / or object oriented programming high-level language and / or in assembly / machine language. As used herein, the terms "machine-readable medium" and "computer-readable medium" refer to any computer program product, non-transitory computer-readable medium, apparatus, and / or device (e.g., magnetic disks, optical disks, memories, programmable logic devices (PLDs)) used to provide machine instructions and / or data to a programmable processor, including a machine-readable medium that receives machine instructions as a machine-readable signal. The term "machine-readable signal" refers to any signal used to provide machine instructions and / or data to a programmable processor.Various implementations of the systems and techniques described herein may be implemented in digital electronic and / or optical circuitry, integrated circuitry, specially designed ASICs (application specific integrated circuits), computer hardware, firmware, software, and / or combinations. These various implementations may include the implementation in one or more computer programs executable and / or interpretable on a programmable system including at least one programmable processor, which may be a special purpose or general purpose processor coupled to receive data and instructions from a storage system, at least one input device, and at least one output device, and to send data and instructions to a storage system, at least one input device, and at least one output device.The processes and logic flows described in this application text may be performed by one or more programmable processors, also referred to as data processing hardware, that execute one or more computer programs to perform functions by acting on input data and generating output. The processes and logic flows may also be performed by special purpose logic circuitry, e.g., an FPGA (a field programmable gate array) or an ASIC (an application specific integrated circuit). The processors suitable for executing a computer program illustratively include both general purpose and special purpose microprocessors and any one or more processors of any type of digital computer. Generally, a processor receives instructions and data from a read-only memory or a random-access memory, or both. The essential elements of a computer are a processor for executing instructions and one or more memory devices for storing instructions and data. Generally, a computer also includes or is operatively coupled to one or more mass storage devices for storing data, e.g., magnetic, magneto-optical, or optical disks, to receive data from or send data to them, or both. However, a computer does not need to have such devices. Computer readable media suitable for storing instructions and data of a computer program include all forms of non-volatile memory, media and storage devices including, by way of example, semiconductor storage devices, e.g., EPROM, EEPROM, and flash memory devices, magnetic disks, e.g., internal hard disks or removable disks, magneto-optical disks, and CD-ROM and DVD-ROM disks. The processor and memory may be supplemented by or incorporated into special purpose logic circuitry.To provide interaction with a user, one or more aspects of the invention may be implemented in a computer having a display device, e.g., a CRT (cathode ray tube), an LCD (liquid crystal display) monitor, or a touchscreen, for displaying information to the user, and optionally a keyboard and a pointing device, e.g., a mouse or trackball, through which the user may provide input to the computer. Other types of devices may also be used to provide interaction with the user; for example, feedback provided to the user may be any form of sensory feedback, e.g., visual feedback, audible feedback, or tactile feedback; while input from the user may be received in any form including acoustic, voice, or tactile input. Additionally, a computer may interact with a user by sending documents to and receiving documents from a device used by the user; e.g., by sending web pages to a web browser on a user's client device in response to requests received from the web browser.Referring now to FIG. 1, an exemplary vehicle operating environment 10 is provided to illustrate the principles of the present invention. The vehicle operating environment 10 includes a vehicle 100 and a vehicle service center 20. However, according to other examples, the vehicle operating environment 10 may include multiple vehicle service centers 20 that are in communication via a network 40 (e.g., the Internet, cellular networks).The vehicle 100 includes a vehicle management system 110, a sensor system 120, a steering system 140, a vehicle dynamics system 150, and an advanced driver assistance system (ADAS) 160. As the vehicle 100 maneuvers in the environment 10, the sensor system 120 includes various sensor subsystems 122, 122 a- 122 cconfigured to acquire sensor data 123, 123 a- 123 crelative to the characteristics of the environment 10 and / or the status of the vehicle 100. Sensor subsystems 122 include, for example, an exterior vehicle sensor subsystem 122a configured to measure or obtain exterior environment data 123a, such as lane markings or surrounding objects (e.g., vehicles, pedestrians), an interior sensor subsystem 122b configured to measure interior environment data 123b, such as vehicle occupancy, and / or an ADAS sensor subsystem 122c configured to measure or obtain vehicle operation data 123c, such as operating parameters. The ADAS sensor subsystem 122 cmay include an inertial measurement unit (IMU), one or more wheel speed sensors, as well as other sensors for obtaining vehicle operating data such as wheel speed, steering wheel position, yaw rate, and lateral acceleration. As the sensor system 120 detects the sensor data 123, a computing system 130 is configured to store, process, and / or transmit the sensor data 123 within the vehicle operating environment 10. To perform computing tasks related to the sensor data 123, the computing system 130 of the vehicle 100 includes data processing hardware 132 and storage hardware 134. The computing hardware 132 is configured to execute the instructions stored in the storage hardware 134 to perform computing tasks related to the operation and management of the vehicle 100. Generally, the computing system 130 refers to one or more locations of the computing hardware 132 and / or the storage hardware 134.According to some examples, the computing system 130 is a local system located in the vehicle 100. When located in the vehicle 100, the computing system 130 may be centralized (i.e., centralized at a single location / area in the vehicle 100, e.g., a vehicle control unit), decentralized (i.e., located at different locations in the vehicle 100), or a hybrid combination of both (e.g., with a majority of centralized hardware and a minority of decentralized hardware). To illustrate some differences, a centralized computing system 130 may allow processing to occur at an activity location, while a centralized computing system 130 may allow a central processing node to communicate with systems located at different locations in the vehicle 100.Additionally or alternatively, the computing system 130 includes computing resources located remotely from the vehicle 100. For example, the computing system 130 may communicate with a remote vehicle computing system 30 (e.g., a remote computer / server or cloud-based environment) via the network 40. Much like the computing system 130, the remote vehicle computing system 30 includes remote computing resources, such as remote computing hardware 32 and remote storage hardware 34. According to some examples, the computing system 130 is configured to use the remote computing resources 32, 34 as extensions of the computing resources 132, 134, such that resources of the computing system 130 may be stored on the resources of the remote vehicle computing system 30.In FIG. 1, one or more wheels 102 (i.e., the front wheels 102 aand the rear wheels 102 b) are coupled to a suspension 104 of the vehicle 100. The steering system 140 may monitor and control the position and / or direction of the wheels 102. For example, the steering system 140 may include a steering column 142 coupled to the suspension 104 and a steering wheel 144 coupled to the steering column 142. The steering system 140 may include one or more additional components, such as a steering housing 146 and a steering gear 148, such that torque may be applied to the steering column 143, whether performed by an engine coupled to the steering column 142 or by a driver via the steering wheel 144, to maintain control and position of the front wheels 102 a.The vehicle dynamics control system 150 may monitor and control one or more electronic aspects of the vehicle 100, such as continuously monitoring and / or controlling a state 152 of the vehicle 100, as shown in FIG. 2A. The steering system 140 may provide an actual road wheel angle 149 as an input to the vehicle dynamics control system 150, which may change the state 152 of the vehicle 100. State 152 may include, for example, a lateral position 152 a, a rate of lateral position 152 b, a heading 152 c, and / or a rate of heading change 152 d.The ADAS 160 may monitor and control one or more electronic aspects of the vehicle 100. For example, the ADAS 160 may monitor and control one or more subsystems of the vehicle 100, such as the steering system 140. In other words, the ADAS 160 may communicate with the steering system 140 to maintain good tracking after an automated driving system of the vehicle is enabled by the driver while the vehicle 100 is at rest, for example, or driving at a low speed. In FIGS. 1 and 2A, the ADAS 160 may include one or more modules for determining one or more operating parameters of the vehicle 100. For example, the ADAS 160 may be configured to include a tracking control module 161, an automated driving module 162, and a steering control module 166. The automated driving module 162 may be configured to communicate with the sensor system 120 and provide a planned or intended path 163 for the vehicle 100. The planned path 163 may be accompanied by a reference trajectory 164, 164 a- 164 dthat may be provided as an input to the trajectory tracking control module 161. The lane following control module 161 may receive the state 152, 152 a- 152 dfrom the vehicle dynamics control system 150 and the reference lane 164, 164 a- 164 dfrom the automated driving module 162 and calculate a commanded steering angle 165. The commanded steering angle 165 may be provided to the steering control module 166 to calculate a torque 168 for the steering system 140. The steering system 140 may change the calculated torque 168 and adjust the road wheel angle 149 accordingly.The automated driving module 162 may be enabled by the driver or otherwise while the vehicle 100 is at rest or is traveling at a low speed such that an initial road wheel angle 149 amay be different from a desired or calculated steering angle 201 (discussed in more detail below). In some cases, if the vehicle 100 were to initiate travel at the initial road wheel angle 149 a, the vehicle 100 may deviate from the designated path 163 provided by the automated driving module 162. Thus, as discussed below, the commanded steering angle 165 may be calculated such that the road wheel angle 149 may be adjusted by the steering system 140 before the vehicle or driver initiates the trip.In FIG. 2A, the commanded steering angle 165 may be calculated using a controller, such as a model predictive controller (MPC) 200. The model predictive controller 200 may be configured with constraints 202, a low speed plant model 204, as well as weights and horizons 206. The constraints 202 may be desirable for maintaining the position of the vehicle 100 within a lane on a road and / or desirable for preventing the vehicle 100 from driving off the road. Generally, at low speeds, the plant model 204 is a model of the vehicle 100 that may assist in making predictions about the behavior (e.g., lane following) of the vehicle 100. The weights and horizons 206 may be calibrated and used by the MPC 200, and more particularly, by a cost equation 208, to determine which predicted path (i.e., which commanded steering angle) is desirable for the vehicle 100. The cost V can be calculated using the following equation:The cost V may be referred to, for example, as a weighted squares sum of one or more variables or the sum of the input, output, input rate, and slip variables. According to the present example, the input may be the wheel angles 149, while the output may be the lateral position 152 a, the rate of lateral position 152 b, the heading 152 c, and the rate of heading change 152 dof the vehicle 100. The slip variable may be provided such that the lateral position 152 a, the rate of the lateral position 152 b, the heading 152 c, and the rate of the heading change 152 dmay track or be close to the target reference value for the lateral position 164 b.A path following quality index (PTQI) 210 is also used to determine whether it is necessary to adjust the road wheel angle 149 prior to engagement of the automated driving system. According to the present example, the PTQI 210 is a dimensionless nominal value (i.e., 0 to 1). The PTQI 210 is determined using the following equation:The PTQI 210 may be referred to as a product of the lateral deviation, the merging time, and the steering angle. y m is referred to as a maximum distance from a nominal path. y engage is referred to as a maximum distance threshold for intervention. t m is referred to as the time required to merge into the nominal path depending on system inertia and road condition (e.g., slope, slope, and surface friction). t max is referred to as a maximum allowable time to merge into the nominal path. δ 0 is used to refer to the initial road wheel angle 149a while δ opt is used, To denote the calculated steering angle 201. w 1, w 2, w 3 are weights referred to as a relevance factor of each parameter. These weights should sum to one (1) and can be adjusted or calibrated as needed.In FIG. 3A, a first path 301A of the vehicle 100 to a center of a lane 304 is shown based on the initial road wheel angle 149 a, a second path 302A of the vehicle 100 to the center of the lane 304 is shown based on the calculated steering angle 201, and a third path 303A of the vehicle 100 to the center of the lane 304 is shown based on the commanded steering angle 165. Generally, if the difference between the first path 301A and the second path 302A is not significant and lane departure is unlikely, then the steering system 140 may use the initial road wheel angle 149 abecause intervention of the vehicle steering system 140 based on the commanded steering angle 165 would not result in a significant change in the state 152 of the vehicle 100. The PTQI 210 may be used to determine whether a standstill intervention of the steering system 140 or a driver intervention is required to modify the steering angle. If the PTQI 210 is less than or equal to a first threshold (e.g., 1) and greater than a second threshold (e.g., 0.75) or is between the first and second thresholds and one (1), a driving maneuver with the initial road wheel angle 149 acan be initiated because, for example, good tracking of the designated path 163 is likely.In FIG. 3B, a first path 301B of the vehicle 100 to the center of the lane 304 is shown based on the initial road wheel angle 149 a, a second path 302B of the vehicle 100 to the center of the lane 304 is shown based on the calculated steering angle 201, and a third path 303B of the vehicle 100 to the center of the lane 304 is shown based on the commanded steering angle 165. Generally, if the difference between the first path 301B and the second path 302B is significant and lane departure is possible, then engaging the steering system 140 based on the commanded steering angle 165 may be desirable so that good tracking of the vehicle 100 may be maintained. The PTQI 210 may be used to determine whether a standstill intervention of the steering system 140 or a driver intervention is required to modify the steering angle. If the PTQI 210 is less than or between the second threshold (e.g., 0.75) and greater than or equal to a third threshold (e.g., 0.50), the steering control module 166 may provide the torque 168 to the control system 140 based on the commanded steering angle 165 prior to initiating a driving maneuver.In FIG. 3C, a first path 301C of the vehicle 100 to the center of the lane 304 is shown based on the initial road wheel angle 149 a, a second path 302C of the vehicle 100 to the center of the lane 304 is shown based on the calculated steering angle 201, and a third path 303C of the vehicle 100 to the center of the lane 304 is shown based on the commanded steering angle 165. According to the present example, if the difference between the first path 301C and the second path 302C is excessive and lane departure is likely, then intervention of the steering system 140 based on the commanded steering angle 165 may be desirable so that good tracking of the vehicle 100 may be maintained. According to this example, engaging the steering system 140 may require the driver of the vehicle 100 to adjust the steering wheel 144. The PTQI 210 may be used to determine whether a standstill intervention of the steering system 140 or a driver intervention is required to modify the steering angle. If the PTQI 210 is less than the third threshold (e.g., 0.50) and greater than or equal to a fourth threshold (e.g., 0), the operator or driver may need to apply torque to the steering system 140 prior to initiating a driving maneuver via the steering wheel 144 based on the commanded steering angle 165. The vehicle management system may be configured to instruct the driver of the vehicle 100 via the user interface 170 to manually adjust the steering angle to the commanded steering angle 165 via the steering wheel 144.Additionally or alternatively, the tracking quality index may be defined as a function of predicted future vehicle conditions (e.g., lateral position, rate of lateral position, heading, and rate of heading change) and the intended future trajectory (e.g., right turn, left turn, straight ahead, etc.).In FIG. 3D, situation awareness of the vehicle 100 may be desirable to engage the steering system 140. For example, if the vehicle 100 is at an intersection in a left turn lane, it may be desirable to engage the steering system 140 so that the vehicle 100 may exhibit good lane following when initiating a driving maneuver to complete a left turn. As shown in FIG. 3D, a first path 301D of the vehicle 100 to the center of the lane 304 is shown based on the initial road wheel angle 149 a, a second path 302D of the vehicle 100 to the center of the lane 304 is shown based on the calculated steering angle 201, and a third path 303D of the vehicle 100 to the center of the lane 304 is shown based on the commanded steering angle 165. Generally, according to the present example, if the difference between the first path 301D and the second path 302D is excessive and significant path deviation is likely, then engaging the steering system 140 based on the commanded steering angle 165 may be desirable so that good tracking of the vehicle 100 may be maintained.In FIG. 4, a method 400 for determining whether an intervention of a steering system of the vehicle 100 at standstill or at low speed is required before a driving maneuver is initiated is provided. At 402, method 400 is initiated. In practical terms, the method 400 may be initiated by the vehicle operator upon turning on the vehicle 100.At 404, driver input to enable the automated driving system may be detected by the vehicle management system 110. For example, the driver of the vehicle 100 may enable the automated driving system via the steering wheel 144 (e.g., by pressing a button) or via the user interface 170.At 406, the designated path 163 of the vehicle 100 may be generated with the automated driving module 162 using the sensor data 123 of the sensor system 120.At 408, the reference trajectory 164 may be determined at the automated driving module 162 and provided to the trajectory tracking control module 161.At 410, any geometric error with respect to the designated path 163 may be determined and provided to the MPC 200 for determining the calculated steering angle 201.At 412, the commanded steering angle 165 may be determined based on the intended path of the vehicle.At 414, the tracking quality index 210 may be calculated. As mentioned above, the PTQI 210 may be desirable for determining whether the steering system should be engaged based on the commanded steering angle 165 or whether the initial road wheel angle 149 acan be used to initiate a steering maneuver. If the PTQI 210 is between 0.75 and 1, the driving maneuver with the initial steering angle is initiated again. If the PTQI 210 is between 0.50 and 0.75, the vehicle steering system 140 is engaged to adjust the steering angle based on the commanded steering angle 165 before the driving maneuver is initiated. If the PTQI 210 is between 0 and 0.5, the vehicle management system 110 may be configured to instruct an operator of the vehicle 100 to manually adjust the steering angle based on the commanded steering angle 165 before initiating the driving maneuver.At 416, lane following may be affected by one or more factors such as road type and weather. Evaluating one or more external factors via the sensor system 120 and predicting performance degradation may be desirable so that the road wheel angle 149 may be adjusted accordingly.At 418, the calculated steering angle 201 may be determined at the track following control module 161.At 420, the vehicle 100 may or may not engage the steering system 140 to adjust the steering angle of the vehicle 100 prior to initiating a driving maneuver. In other words, whether the vehicle 100 or the driver adjusts the road wheel angle 149 based on the commanded steering angle 165 may be reached at 420. In steady state intervention vehicle scenarios (e.g., FIGS. 3A-3C ) or situational awareness intervention vehicle scenarios (FIG. 3D ), the road wheel angle may or may not be adjusted based on the commanded steering angle 165.The method 400 is completed at 422.

Claims

A computer-implemented method that, when executed by computing hardware (132), causes the computing hardware (132) to perform operations comprising: detecting a request to enable an automated driving system of a vehicle (100) while the vehicle (100) is at rest or is traveling at a low speed; determining a designated path (163) of the vehicle (100); determining an initial steering angle (149); calculating a target steering angle (201) based on the designated path (163); calculating a commanded steering angle (165); evaluating the initial steering angle (149) against the target steering angle (201); either (i) initiating a driving maneuver with the initial steering angle (149), or (ii) adjusting the steering angle based on the commanded steering angle (165) prior to initiating the driving maneuver; and evaluating a path following quality index (PTQI) determined using the equation: P T Q I = (1-w 1 y m y e n g a g e )× (1-w 2 t m t m a x )× (1-w 3 a b s (δ 0-δ o p t ) a b s (m a x (δ 0-δ o p t )) ), where y m is a maximum distance from a nominal path, y engage is a maximum distance threshold for intervention, t m is the time required to thread into the target path depending on system inertia and road condition, t max is a maximum allowable time to thread into the target path, δ 0 is the initial road wheel angle 149, δ opt is the target steering angle (201), and w 1, w 2, and w 3 are weights that are a relevance factor of each parameter, where the weights should sum to one and can be adjusted or calibrated as needed.The method of claim 1, wherein adjusting the steering angle further comprises adjusting the initial steering angle (149) prior to initiating the driving maneuver with a vehicle steering system (140).The method of claim 1, wherein adjusting the steering angle prior to initiating the driving maneuver further comprises instructing an operator of the vehicle (100) to manually adjust the initial steering angle (149) based on the commanded steering angle (165) prior to initiating the driving maneuver.The method of claim 1, wherein if the tracking quality index is between a first threshold and a second threshold, then the driving maneuver is initiated with the initial steering angle (149).The method of claim 1, wherein if the tracking quality index is less than a second threshold and greater than or equal to a third threshold, a vehicle steering system (140) configured to adjust the steering angle adjusts the steering angle based on the commanded steering angle (165) before initiating the driving maneuver.The method of claim 1, wherein if the tracking quality index is greater than a fourth threshold and less than a third threshold, a vehicle management system (110) configured to instruct an operator of the vehicle (100) to manually adjust the steering angle based on the commanded steering angle (165) before initiating the driving maneuver.The method of claim 1, wherein the evaluating the tracking quality index is a function of the predicted future vehicle conditions and the intended future trajectory.The method of claim 1, wherein evaluating the tracking quality index further includes evaluating the initial steering angle (149) of the vehicle (100) using a predictive controller (200) and a vehicle model at low speeds.The method of claim 1, wherein determining an initial steering angle (149) further comprises determining the initial steering angle (149) while the vehicle (100) is travelling at a low speed or at rest.

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