What are field based operations

DE102016113902A1 - Field-based torque steering control - Google Patents

Field-based torque steering control Download PDF

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Publication number
DE102016113902A1
DE102016113902A1DE102016113902.5ADE102016113902ADE102016113902A1DE 102016113902 A1DE102016113902 A1DE 102016113902A1DE 102016113902 ADE102016113902 ADE 102016113902AEN 102016113902 102016113902A190
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DE
Germany
Prior art keywords
potential
vehicle
torque
computer
steering
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Pending
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DE102016113902.5A
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English (en)
Inventor
Edwin Olson
Enric Galceran
Ryan M. EUSTICE
James Robert McBride
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Ford Global Technologies LLC
University of Michigan
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Ford Global Technologies LLC
University of Michigan
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Priority to US14 / 814,856priorityCriticalpatent / US9618938B2 / en
Priority to US14 / 814,856priority
Application filed by Ford Global Technologies LLC, University of MichiganfiledCriticalFord Global Technologies LLC
Publication of DE102016113902A1publicationCriticalpatent / DE102016113902A1 / de
Pendinglegal-statusCriticalCurrent

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Images

Classifications

    • B — PERFORMING OPERATIONS; TRANSPORTING
    • B62 — LAND VEHICLES FOR TRAVELING OTHERWISE THAN ON RAILS
    • B62D — MOTOR VEHICLES; TRAILERS
    • B62D1 / 00 — Steering controls, i.e. means for initiating a change of direction of the vehicle
    • B62D1 / 24 — Steering controls, i.e. means for initiating a change of direction of the vehicle not vehicle-mounted
    • B62D1 / 28 — Steering controls, i.e. means for initiating a change of direction of the vehicle not vehicle-mounted non-mechanical, e.g. following a line or other known markers
    • B62D1 / 283 — Steering controls, i.e. means for initiating a change of direction of the vehicle not vehicle-mounted non-mechanical, e.g. following a line or other known markers for unmanned vehicles
    • G — PHYSICS
    • G05-CONTROLLING; REGULATING
    • G05D — SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D1 / 00 — Control of position, course or altitude of land, water, air, or space vehicles, e.g. automatic pilot
    • G05D1 / 02 — Control of position or course in two dimensions
    • G05D1 / 021 — Control of position or course in two dimensions specially adapted to land vehicles
    • G05D1 / 0212 — Control of position or course in two dimensions specially adapted to land vehicles with means for defining a desired trajectory
    • B — PERFORMING OPERATIONS; TRANSPORTING
    • B60 — VEHICLES IN GENERAL
    • B60W — CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W10 / 00 — Conjoint control of vehicle sub-units of different type or different function
    • B60W10 / 20 — Conjoint control of vehicle sub-units of different type or different function including control of steering systems
    • B — PERFORMING OPERATIONS; TRANSPORTING
    • B60 — VEHICLES IN GENERAL
    • B60W — CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W30 / 00 — Purposes of road vehicle drive control systems not related to the control of a particular sub-unit, e.g. of systems using conjoint control of vehicle sub-units, or advanced driver assistance systems for ensuring comfort, stability and safety or drive control systems for propelling or retarding the vehicle
    • B60W30 / 08 — Active safety systems predicting or avoiding probable or impending collision or attempting to minimize its consequences
    • B60W30 / 09 — Taking automatic action to avoid collision, e.g. braking and steering
    • B — PERFORMING OPERATIONS; TRANSPORTING
    • B60 — VEHICLES IN GENERAL
    • B60W — CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W30 / 00 — Purposes of road vehicle drive control systems not related to the control of a particular sub-unit, e.g. of systems using conjoint control of vehicle sub-units, or advanced driver assistance systems for ensuring comfort, stability and safety or drive control systems for propelling or retarding the vehicle
    • B60W30 / 10 — Path keeping
    • B60W30 / 12 — Lane keeping
    • B — PERFORMING OPERATIONS; TRANSPORTING
    • B60 — VEHICLES IN GENERAL
    • B60W — CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W40 / 00 — Estimation or calculation of non-directly measurable driving parameters for road vehicle drive control systems not related to the control of a particular sub unit, e.g. by using mathematical models
    • B60W40 / 02 — Estimation or calculation of non-directly measurable driving parameters for road vehicle drive control systems not related to the control of a particular sub unit, e.g. by using mathematical models related to ambient conditions
    • B60W40 / 06 — Road conditions
    • B — PERFORMING OPERATIONS; TRANSPORTING
    • B62 — LAND VEHICLES FOR TRAVELING OTHERWISE THAN ON RAILS
    • B62D — MOTOR VEHICLES; TRAILERS
    • B62D15 / 00 — Steering not otherwise provided for
    • B62D15 / 02 — Steering position indicators; Steering position determination; Steering aids
    • B62D15 / 025 — Active steering aids, e.g. helping the driver by actively influencing the steering system after environment evaluation
    • B — PERFORMING OPERATIONS; TRANSPORTING
    • B62 — LAND VEHICLES FOR TRAVELING OTHERWISE THAN ON RAILS
    • B62D — MOTOR VEHICLES; TRAILERS
    • B62D6 / 00 — Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits
    • B62D6 / 04 — Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits responsive only to forces disturbing the intended course of the vehicle, e.g. forces acting transversely to the direction of vehicle travel
    • G — PHYSICS
    • G05-CONTROLLING; REGULATING
    • G05D — SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D1 / 00 — Control of position, course or altitude of land, water, air, or space vehicles, e.g. automatic pilot
    • G05D1 / 02 — Control of position or course in two dimensions
    • G — PHYSICS
    • G05-CONTROLLING; REGULATING
    • G05D — SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D1 / 00 — Control of position, course or altitude of land, water, air, or space vehicles, e.g. automatic pilot
    • G05D1 / 02 — Control of position or course in two dimensions
    • G05D1 / 021 — Control of position or course in two dimensions specially adapted to land vehicles
    • G05D1 / 0276 — Control of position or course in two dimensions specially adapted to land vehicles using signals provided by a source external to the vehicle
    • G05D1 / 0278 — Control of position or course in two dimensions specially adapted to land vehicles using signals provided by a source external to the vehicle using satellite positioning signals, e.g. GPS
    • G — PHYSICS
    • G05-CONTROLLING; REGULATING
    • G05D — SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D2201 / 00 — Application
    • G05D2201 / 02 — Control of position of land vehicles
    • G05D2201 / 0213-Road vehicle, e.g. car or truck

Abstract

Description

  • Autonomous vehicles can be steered by adjusting a steering angle of the vehicle to follow a center line of a path. This deviates from normal human driving behavior, which takes into account restoring torques which are exerted on the steering column during driving maneuvers and which also usually allows more deviation from a center line.
  • FIG. 13 is a diagram of an exemplary vehicle with torque steering control based on a potential field.
  • FIG. 14 is a diagram of the exemplary vehicle of FIG. 10 on a road with a representation of a potential field.
  • Figure 3 is a diagram of an example control for a field-based torque steering system.
  • Figure 13 is a diagram of an exemplary process for a field-based torque steering system.
  • Figure 13 is a test trajectory diagram for testing an exemplary field-based torque steering system.
  • Figure 13 is a graph depicting vehicle trajectory during a first portion of a test of an exemplary field-based torque steering system.
  • FIG. 13 is a graph depicting vehicle trajectory during a second portion of testing the exemplary field-based torque steering system as shown in FIG.
  • 13 is a graph depicting vehicle trajectory during a third portion of testing the exemplary field-based torque steering system as shown in FIGS.
  • 13 is a graph depicting vehicle trajectory during a fourth portion of testing the exemplary field-based torque steering system as shown in FIGS.
  • FIG. 14 is a graph showing potential field gradients and applied torque during the first part of the test corresponding to the vehicle trajectory of FIG.
  • FIG. 14 is a graph showing potential field gradients and applied torque during the second part of the test corresponding to the vehicle trajectory of FIG.
  • FIG. 14 is a graph showing potential field gradients and applied torque during the third part of the test corresponding to vehicle trajectory of FIG.
  • FIG. 14 is a graph showing potential field gradients and applied torque during the fourth part of the test corresponding to the vehicle trajectory of FIG.
  • Fig. 13 is a graph showing a vehicle trajectory during a first part of a steering wheel angle (SWA) steering system test.
  • FIG. 14 is a graph showing a vehicle trajectory during a second part of the steering wheel angle (SWA) steering system test shown in FIG.
  • FIG. 13 is a graph showing a vehicle trajectory during a third part of the steering wheel angle (SWA) steering system test shown in FIGS.
  • FIG. 14 is a graph indicating applied torque during the first part of the steering wheel angle (SWA) steering system test corresponding to the vehicle trajectory of FIG.
  • FIG. 14 is a graph indicating applied torque during the second part of the steering wheel angle (SWA) steering system test corresponding to the vehicle trajectory of FIG.
  • FIG. 14 is a graph indicating applied torque during the third part of the steering wheel angle (SWA) steering system test corresponding to the vehicle trajectory of FIG.
  • Figure 3 is a graph showing the tracking performance of a field-based torque steering system.
  • Figure 13 is a graph showing the tracking performance of an SWA steering system.
  • is a graph showing the total work (in joules) of a field-based torque steering system and an SWA steering system.
  • 13 is a diagram of one of the exemplary field-based steering control vehicle on a road with a first potential field along a target path and a second potential field associated with an obstacle.
  • DETAILED DESCRIPTION
  • Steering an autonomous vehicle with the aid of potential fields and torque steering control enables the vehicle to deviate from a target path in a defined corridor and to approximate a human driving style. The field-based torque steering control system defines a potential field that represents the travel corridor for the vehicle along a target path that the vehicle is to travel on. The system recognizes a pose of the vehicle relative to the potential field at a current time. A “pose of the vehicle” includes at least one position of the vehicle at a specific time, and further information relating to the vehicle, such as a direction of movement of the vehicle, a speed of the vehicle, an acceleration of the vehicle, etc., can also include the determined Time. On the basis of the vehicle pose relative to the potential field, the system determines a torque to be applied to a steering column of the vehicle. The potential field has an attractive potential that guides the vehicle in such a way that it remains in the corridor.
  • As shown by test results, such a field-based torque steering system can provide tracking similar to that of Steering Wheel Angle (SWA) steering systems currently being developed for autonomous vehicles, while spending less work (measured in joules) on the Steer vehicle. This can result in a driving experience that feels more natural, similar to that of a vehicle being driven by a person.
  • EXEMPLARY SYSTEM ELEMENTS
  • An exemplary vehicle with a computer programmed to use potential fields and torque control to steer the vehicle is shown in FIG. The vehicle includes the computer, a Road Network Definition File (RNDF) being stored in one of its memories, one or more data collectors, a user interface and one or more controllers. The vehicle is generally a land vehicle with three or more wheels, e.g. A passenger car, light truck, etc. The vehicle has a front, a rear, a left side and a right side, the terms front, rear, left and right being understood from the perspective of an operator of the vehicle sits in a driver's seat in a standard operating position, d. H. facing a steering wheel.
  • The vehicle computer generally includes a processor and memory, the memory comprising one or more forms of computer readable media and storing instructions executable by the processor to perform various operations, including those disclosed herein. Furthermore, one or more other data processing devices can include and / or be communicatively coupled to the computer of the vehicle, which are incorporated into the vehicle in order to monitor and / or regulate various vehicle components, e.g. B. electronic control units (ECUs), such as the controller. The vehicle's computer is generally programmed and set up for data transmission on a controller area network bus (CAN bus) or the like.
  • The vehicle's computer can also have a connection to an on-board diagnostic connector (OBD-II), a CAN bus (controller area network bus) and / or other wired or wireless mechanisms. Via one or more such data transmission mechanisms, the computer can transmit messages to various devices in a vehicle and / or receive messages from the various devices, e.g. B. actuators, sensors, etc., including data collectors and controllers. Alternatively or additionally, in cases where the vehicle actually comprises multiple devices, the CAN bus or the like can be used for data transfers between devices, which are represented in this disclosure as the computer.Furthermore, the computer can be configured to exchange data with other devices using various wired and / or wireless network technologies, e.g. B. Cellular, Bluetooth, a universal serial bus (USB), wired and / or wireless packet networks, etc.
  • Collected data are generally stored in a memory of the computer. The collected data can include various data collected in the computer by data collectors and / or derived therefrom. Collected data can also be exchanged via data, e.g. B. with sources outside the vehicle, count received data. Examples of data collected may include data relating to the vehicle such as a location of objects, a type of objects, a location and speed of other vehicles, road features, etc. in an area in which the vehicle operates. The collected data can also include data relating to a vehicle condition, such as the speed of the vehicle, the direction of movement of the vehicle, torque applied to a steering column, engine speed, etc. The data can also include location data or map data received from a global positioning system (GPS), for example Count the area in which the vehicle is operating or planning to operate. In general, the data collected can include any data that can be collected by the data collectors, received through vehicle-to-vehicle (V2V) or vehicle-to-vehicle (V2I) communications, through satellite communications other sources can be collected or received and / or can be calculated from such data.
  • The computer can also be programmed to collect data relating to vehicle objectives as well as other data pertaining to the vehicle. "Objective" of the vehicle is used here in the sense that it refers to goals of a trip, such as a final destination, intermediate destinations, a route to be traveled, a preferred arrival time, an applicable driving style (conservative, sporty), etc.
  • For example, the computer may have received input from the user through the user interface indicating the user's destination and the route he would like to take. On the basis of the data collected, the computer can, as described below, plan a target route to a desired destination in the form of driving instructions on a road map. The computer can also define a corridor of acceptable deviation around the target path. On the basis of the defined corridor, the computer can define and send commands to the vehicle controllers in order to control the vehicle by adjusting a torque applied to a steering column in such a way that it moves along the target path and in the corridor.
  • In general, each controller may have a processor programmed to receive instructions from the vehicle, execute the instructions, and send messages to the computer. An electronic control unit (ECU), which is known and also has programming for operation as described here, is an example of a controller. Furthermore, an actuator or the like can include or be communicatively coupled to each of the controllers, which is provided in order to actuate a vehicle component, e.g. Braking, steering, throttle, etc. For example, a torque controller may include a processor and a motor to apply torque to a steering column. In this example, upon receiving an instruction from the computer, the processor can activate the engine to adjust the steering of the vehicle.
  • Furthermore, the controllers can each have sensors or otherwise function as data collectors in order to provide the computer with data relating to the speed of the vehicle, steering angle, height of a suspension and so on. For example, the torque controller can send data to the computer corresponding to the torque applied to the steering column.
  • Data collectors can be a variety of devices. For example, data collectors can be LIDAR, radar, video cameras, ultrasonic sensors, infrared sensors for recording the environment. Data collectors can also include components that collect dynamic data of the vehicle, such as speed, yaw rate, steering angle, etc. Furthermore, the above examples are not intended to be limiting. Other types of data collectors, such as accelerometers, gyroscopes, pressure sensors, thermometers, barometers, altimeters, etc., could be used to provide data to the vehicle.
  • A Road Network Definition File (RNDF) can contain encoded topological-metric maps of the road networks where the vehicle might operate. The topological-metric maps contain latitude and longitude coordinates for road features and other objects in the vicinity and are encoded on the basis of a derivative of the RNFD file format. The RNDF can supply map data, etc., to the computer.
  • The vehicle may further include a user interface that may be included in or communicatively coupled to the vehicle. The user interface can e.g. Be used to receive input from a user regarding the desired destination of the vehicle, the desired route to be taken, and so on. The interface may have one or more output devices such as a display, speakers, etc. to convey information to a user. The interface may further include one or more input devices such as a touchscreen display, keyboard, gesture recognition device, switches, etc. for receiving input from the user.
  • A field-based torque steering system for controlling a vehicle along a desired path may include a corridor around the path and a steering controller using a torque-based interface. The corridor can be constructed from potential fields that guide the vehicle along the target path. The potential fields can have a steering component that guides the vehicle towards the target path, and an obstacle component that guides the vehicle away from obstacles, e.g. B. of static objects, other vehicles, etc. at a predetermined distance from the target path. The predetermined distance can be defined, for example, as being within a predetermined lateral distance, e.g. B. 20 meters from the Sollweg. As a further example, the predetermined distance can be defined as being within the corridor represented by the potential field. As a further example, the predetermined distance can be a distance associated with a condition of the vehicle (position, speed, acceleration, etc.) and / or associated with conditions in the surrounding area (type of road, weather conditions, etc.). The steering controller can apply a torque to a steering column which is determined on the basis of a position and / or a projected future position of the vehicle relative to the potential field.
  • Construct a potential field
  • A potential field that should represent the driving corridor of the vehicle can be constructed using a potential energy function: U:
    where x is a point in a two-dimensional plane of the vehicle, Uatt is an attractive potential that leads the vehicle to the target path, and Urep is a repulsive potential that leads the vehicle away from obstacles in the vicinity. The goal of the vehicle is to minimize the energy of this potential by commanding a steering torque input based on the negative gradient of the potential field:
  • The attractive potential Uatt can be generated around the target path, e.g. B. around a center of a lane, which can be obtained, for example, as is known, from an existing road network map or using a movement planner. A target path Π is given as a sequence of N two-dimensional waypoints Π = ω1, ..., ωN, the attractive potentials Uatt(x) can for all points x in a local neighborhood of the vehicle, in the form
    can be taken into account, where d (x, Π) is a distance from a point x to a nearest segment in the target path.. It has been found empirically that a quadratic potential, i.e. H. i = 2 provides sufficient control authority to steer the vehicle on the target path, with a linear potential (i = 1) requiring a high proportional gain in a control system, which leads to instability. It was also found that higher orders (i> 2) did not provide significantly improved performance compared to a quadratic potential. Based on this simplification, the potential can be defined as