GB2574448A - Apparatus and method controlling a process - Google Patents

Apparatus and method controlling a process Download PDF

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Publication number
GB2574448A
GB2574448A GB1809342.7A GB201809342A GB2574448A GB 2574448 A GB2574448 A GB 2574448A GB 201809342 A GB201809342 A GB 201809342A GB 2574448 A GB2574448 A GB 2574448A
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GB
United Kingdom
Prior art keywords
vehicle
heading
current
correction value
dependence
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB1809342.7A
Other versions
GB201809342D0 (en
Inventor
Herrera Juan
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Jaguar Land Rover Ltd
Original Assignee
Jaguar Land Rover Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Jaguar Land Rover Ltd filed Critical Jaguar Land Rover Ltd
Priority to GB1809342.7A priority Critical patent/GB2574448A/en
Publication of GB201809342D0 publication Critical patent/GB201809342D0/en
Publication of GB2574448A publication Critical patent/GB2574448A/en
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • G05D1/0268—Control of position or course in two dimensions specially adapted to land vehicles using internal positioning means
    • G05D1/027—Control of position or course in two dimensions specially adapted to land vehicles using internal positioning means comprising intertial navigation means, e.g. azimuth detector
    • 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
    • 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
    • B60W30/18—Propelling the vehicle
    • B60W30/18009—Propelling the vehicle related to particular drive situations
    • B60W30/18145—Cornering
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING 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 TRAVELLING 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
    • B62D6/002—Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits computing target steering angles for front or rear wheels
    • 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
    • B60W2520/00—Input parameters relating to overall vehicle dynamics
    • B60W2520/20—Sideslip angle
    • 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
    • B60W2710/00—Output or target parameters relating to a particular sub-units
    • B60W2710/20—Steering systems
    • B60W2710/207—Steering angle of wheels
    • 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
    • B60W2720/00—Output or target parameters relating to overall vehicle dynamics
    • B60W2720/20—Sideslip angle

Abstract

Means of controlling the steering of a vehicle, comprising determining 430 a heading correction value indicative of a difference between a current trajectory 410 of the vehicle and a desired trajectory 420 of the vehicle, determining 440 a modified desired heading for the vehicle in dependence on the correction value, and determining 460 one or more steering control inputs for the process in dependence on a current heading of the vehicle and the modified desired heading. The heading correction value may also be dependent on the current and desired positions of the vehicle and may be an angle between the positions. There may be defined a gain factor applied to the heading correction value in order to obtain the modified desired heading. A heading error value may be determined using the modified desired heading and the current heading of the vehicle. Steering inputs for the vehicle may be determined using the heading error value.

Description

APPARATUS AND METHOD CONTROLLING A PROCESS
TECHNICAL FIELD
The present disclosure relates to apparatus and methods and particularly, but not exclusively, to apparatus and methods for controlling a process. Aspects of the invention relate to a method, to a controller, to a system, to a vehicle and to computer software.
BACKGROUND
In a vehicle operating in an autonomous or partially autonomous mode, the vehicle may be controlled to achieve a desired state from a current state of the vehicle. The current and desired states of the vehicle may be defined by a plurality of parameters, such as a heading and a position of the vehicle. Control of the vehicle is often achieved in dependence on each of the parameters. However this may require a complex control scheme.
SUMMARY OF THE INVENTION
Aspects and embodiments of the invention provide a method, a controller, a system, a vehicle and computer software as claimed in the appended claims.
According to an aspect of the invention, there is provided a method of controlling a vehicle, comprising determining a heading correction value indicative of a difference between a current trajectory of a vehicle and a desired trajectory of a vehicle, determining a modified desired heading for the vehicle in dependence on the heading correction value, and determining one or more steering inputs for the vehicle in dependence on a current heading of the vehicle and the modified desired heading. Advantageously the process is controlled by means of the current trajectory and the desired trajectory, where the correction value may take account of one or more further parameters.
The heading correction value may be determined in dependence on a current position of the vehicle and a desired position of the vehicle. The heading correction value is advantageously used to also correct for a positional error.
The heading correction value may be determined as an angle between the current position of the vehicle and the desired position of the vehicle. Advantageously the heading correction value is directed toward the desired position of the vehicle.
The heading correction value β is optionally determined as:
- Ύι β = atan \χ2 ~ xfl where Xi, yi are indicative of the current position of the vehicle and x2, y2are indicative of the desired position of the vehicle. Advantageously the heading correction value may be easily calculated taking account of position.
The modified desired heading may be determined in dependence on a desired heading of the vehicle and the heading correction value. The modified desired heading advantageously directs the vehicle toward the desired position of the vehicle.
The modified desired heading may be determined by applying a gain factor to the heading correction value. Advantageously the gain factor controls an extent to which the heading correction value is applied.
Optionally the modified desired heading, 0d’, is determined as:
θ/ = 8d+gP where 0d is the desired heading of the vehicle, g is the gain factor and β is the heading correction value. Advantageously the modified desired heading may be easily calculated.
The method optionally comprises determining a heading error in dependence on the modified desired heading and a current heading of the vehicle. Advantageously the heading error indicates a difference between the modified heading and the current heading.
The heading error, 6e, may be determined as:
9e = θ/ where 0/ is the modified desired heading and 0 is the current heading of the vehicle. Advantageously the modified desired heading may be easily calculated.
The one or more steering inputs for the vehicle are optionally determined in dependence on the heading error. Advantageously the heading error is used as an input to determine the steering input.
According to an aspect of the invention, there is provided a controller, comprising current state input means to receive a signal indicative of a current state of a vehicle, desired state input means to receive a signal indicative of a desired state of a vehicle, processing means arranged to determine a heading correction value indicative of a difference between a current trajectory of a vehicle and a desired trajectory of a vehicle, determine a modified desired heading for the vehicle in dependence on the heading correction value, and determine one or more steering inputs for the vehicle in dependence on a current heading of the vehicle and the modified desired heading, the controller comprising output means arranged to output a signal indicative of the one or more steering inputs for the vehicle.
The controller as described above, wherein:
the input means is an electrical input to receive the signal;
the processing means is one or more electronic processing devices; and the output means is an electrical output to output the signal.
The current state input means may comprise first input means arranged to receive a signal indicative of a current position of the vehicle.
The desired state input means optionally comprises second input means arranged to receive a signal indicative of a desired position of the vehicle; and
The processing means may be arranged to determine the heading correction value in dependence on the current position of the vehicle and the desired position of the vehicle.
The processing means may be arranged to determine the heading correction value as an angle between the current position of the vehicle and the desired position of the vehicle.
The processing means may be arranged to determine the heading correction value β as:
β = atan -----\x2 -x-J where Xi, yi are indicative of the current position of the vehicle and x2, y2are indicative of the desired position of the vehicle.
The desired state input means optionally comprises a third input means arranged to receive a signal indicative of a desired heading of the vehicle.
The processing means is optionally arranged to determine modified desired heading in dependence on a desired heading of the vehicle and the heading correction value.
The processing means is optionally arranged to determine the modified desired heading by applying a gain factor to the heading correction value.
The processing means may be arranged to determine the modified desired heading, 0d’,as:
θα' = θά+ρβ where 0d is the desired heading of the vehicle, g is the gain factor and β is the heading correction value.
Optionally the processing means is arranged to determine a heading error in dependence on the modified desired heading and a current heading of the vehicle.
The processing means may be arranged to determine the heading error, 6e, as:
9e = θ/ where 0/ is the modified desired heading and 0 is the current heading of the vehicle.
The processing means may be arranged to determine one or more steering inputs for the vehicle are determined in dependence on the heading error.
According to an aspect of the invention, there is provided a system comprising a controller according to an aspect of the invention, and control means arranged to receive the one or more signals indicative of the one or more steering inputs and to control the vehicle in dependence thereon.
The control means optionally comprises a steering control means for controlling a steering system of the vehicle. The steering control means may comprise one or more steering control devices. The one or more steering control devices may comprise one or more actuators for, in use, controlling the steering of the vehicle.
According to a still further aspect of the invention, there is provided a vehicle arranged to perform a method according to an aspect of the invention, comprising a controller according to an aspect of the invention or a system according to an aspect of the invention.
According to an aspect of the invention, there is provided computer software which, when executed by a computer, is arranged to perform a method according to an aspect of the invention. The computer software may be stored on a computer readable medium. The computer software may be tangibly stored on the computer readable medium. The computer readable medium may be non-transitory.
Any controller or controllers described herein may suitably comprise a control unit or computational device having one or more electronic processors. Thus the system may comprise a single control unit or electronic controller or alternatively different functions of the controller may be embodied in, or hosted in, different control units or controllers. As used herein the term “controller” or “control unit” will be understood to include both a single control unit or controller and a plurality of control units or controllers collectively operating to provide any stated control functionality. To configure a controller, a suitable set of instructions may be provided which, when executed, cause said control unit or computational device to implement the control techniques specified herein. The set of instructions may suitably be embedded in said one or more electronic processors. Alternatively, the set of instructions may be provided as software saved on one or more memory associated with said controller to be executed on said computational device. A first controller may be implemented in software run on one or more processors. One or more other controllers may be implemented in software run on one or more processors, optionally the same one or more processors as the first controller. Other suitable arrangements may also be used.
Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.
BRIEF DESCRIPTION OF THE DRAWINGS
One or more embodiments of the invention will now be described by way of example only, with reference to the accompanying drawings, in which:
Figure 1 shows an illustration of current and desired trajectories for a vehicle;
Figure 2 shows a schematic illustration of a system according to an embodiment of the invention;
Figure 3 shows a schematic illustration of a controller according to an embodiment of the invention;
Figure 4 shows a method according to an embodiment of the invention;
Figure 5 illustrates an example scenario according to an embodiment of the invention; and
Figure 6 a vehicle according to an embodiment of the invention.
DETAILED DESCRIPTION
Embodiments of the present invention relate to controlling a vehicle where the vehicle state is defined by means of one or more of a plurality of parameters associated with the vehicle. In some embodiments the plurality of parameters comprise a position and heading of the vehicle wherein only the heading of the vehicle is controlled and an error associated with each of the plurality of parameters is reduced, as will be explained.
Referring to Figure 1 there is illustrated a vehicle, generally denoted as 100, illustrated at a first state 110. The first state 110 is a current state of the vehicle 100 at a current or present point in time. For example, the current state 110 may be the vehicle 100 on a navigable path, such as a roadway or other navigable area.
Every state of the vehicle 100 (either present or desired at a respective point in time) is defined by a plurality of parameters. A first parameter is a location or position of the vehicle 100 which may be defined by appropriate coordinates (x, y) which may be with reference to a predetermined coordinate system, for example although not exclusively latitude and longitude. A second parameter is a heading 115 of the vehicle 100 as illustrated in Figure 1 with an arrow which it is noted is offset from a centre of the vehicle 100 for clarity. The heading 115 may be an angle Θ defined with respect to a predetermined coordinate system. The predetermined coordinate system may be defined with respect to the current state of the vehicle i.e. 0current = 0 such that one or more desired headings of the vehicle 100 are with respect to 0current. The heading 115 may be determined with reference to another direction such as, for example, compass heading North, although other references may be used. Arrow 120 indicates a current trajectory of the vehicle 100 i.e. indicating a path which the vehicle 100 is currently following.
In addition, a plurality of intended future states or desired states of the vehicle 100 are illustrated along a desired trajectory 130 of the vehicle 100. Each desired state is indicated with a respective marker 140, 150, 160, 170, 180 denoting the desired position of the vehicle 100 at a respective point in time. Each of the desired states 140, 150, 160, 170, 180 may be associated with a desired position of the vehicle 100 along the navigable path in a direction of travel, or at another position on the navigable area, such as at a parked position, for example. Other desired positions of the vehicle 100 may be envisaged. Each of the desired states 140, 150, 160, 170, 180 may be associated defined by the same set of parameters used to define the current state 110 of the vehicle 100. Thus, as illustrated for first and second desired states 140, 150 each state may be associated with a respective desired heading parameter 145, 155.
Whilst Figure 1 illustrates six desired states 130, 140, 150, 160, 170, 180 of the vehicle 100 it will be appreciated that this is merely illustrative and that other numbers of desired states, such as one, may be envisaged. For ease of explanation an embodiment of the invention will be explained with reference to one desired state of the vehicle 100.
It can be appreciated from Figure 1 that the current trajectory 120 of the vehicle 100 differs from the desired trajectory 130 of the vehicle 100. Embodiments of the invention aim to control a state of the vehicle only by means of controlling the heading of the vehicle 100. That is, it is not necessary to employ specific control of the vehicle position as an error as the vehicle’s position is controlled via control of the vehicle’s heading, as will be explained.
Figure 2 illustrates a system 200 according to an embodiment of the invention which uses the above teaching. The system 200 is a system 200 for controlling a trajectory of a vehicle 100. Whilst the system 200 is described in the context of a land-going vehicle 100, it will be appreciated that, as noted above, this is not limiting.
The system 200 comprises a control means 210 according to an embodiment of the invention, current state determining means 220 for determining one or more parameters of a current state of the vehicle, desired state determining means 230 and vehicle control means 240. In more general terms the current state determining means 220 is arranged to operatively determine a current state of a process and the desired state determining means 230 is arranged to determine a desired state of the process. The vehicle control means 240 may be a means which operatively controls the process.
The control means 210 will be further described with reference to Figure 3 which schematically illustrates an embodiment of the control means 210. The control means 210 may comprise electronic circuitry. The control means 210 may comprise one or more electronic processing devices, or processors, which operably execute computer-readable instructions. The computer-readable instructions may be stored in a memory accessible to the one or more electronic processing devices. The computer readable instructions may, when executed, cause the one or more electronic processing devices to implement a method according to an embodiment of the invention, such as that illustrated in Figure 4. The control means 210 comprises input means to receive a signal indicative of the current state of the vehicle 100. The signal may be an electronic signal which is indicative of current state data. The current state data may be provided by the current state determining means 220. The control means 210 may comprise input means to receive a signal indicative of the desired state of the vehicle 100. The signal may be an electronic signal which is indicative of desired state data. The desired state data may be provided by the desired state determining means 230. The control means 210 comprises output means to output a signal indicative of one or more control inputs which are provided to the vehicle 100. The signal may be an electronic signal, hereinafter vehicle control signal, which is indicative of the one or more vehicle control inputs i.e. provided as an input to one or more vehicle control means. The control signal may be provided to the vehicle control means 240.
Figure 3 illustrates a controller 300 according to an embodiment of the invention. The controller 300 may correspond to the control means 210 illustrated in Figure 2. The controller 300 comprises a heading correction determination means 310 in the form of a heading correction determination module (HCDM) and a modified desired heading determining means 320 in the form of a modified desired heading determinisation module (MDHM) 320. The controller 300 comprises a heading error determining means (HEDM) 330.
The controller 300 comprises a first input means 311, such as an electrical input 311, for receiving a signal indicative of a current position of the vehicle 100 and a second input means input means 312, such as an electrical input 312, for receiving a signal indicative of a desired position of the vehicle 100. The current position and desired position may be defined in terms of a predetermined coordinate system, such as longitude and latitude. Data indicative of the current position and desired position are provided to the HCDM 310. As will be explained, the HCDM 310 is arranged to operatively determine a parameter indicative of a heading correction in dependence on the current position and desired position, as will be explained further with reference to Figures 4 and 5. The parameter is provided to the MDHM 320 as signal 313.
The MDHM 320 is arranged to determine a modified desired heading for reducing an error between current and desired states of the vehicle 100, as will be explained. The MDHM 320 receives the parameter indicative of the heading correction from the MCDM 310. The controller comprises a third input means 321, such as an electrical input, for receiving a signal indicative of a desired heading of the vehicle 100. The MDHM 320 is arranged to determine the modified desired heading in dependence on the parameter indicative of the heading correction and desired heading of the vehicle 100 as will be explained. The MDHM 320 is arranged to output a signal 322 indicative of the modified desired heading.
The HEDM 330 is arranged to determine a heading error in dependence on the modified desired heading 322. The controller comprises a fourth input means 331 for receiving a signal indicative of the current heading of the vehicle 100 and a fifth input for receiving a signal indicative of the desired heading of the vehicle 332.
Figure 4 illustrates a method 400 according to an embodiment of the invention. The method 400 will be explained with reference to Figure 5 which provides an example scenario to illustrate operation of the method 400. The method 400 may be performed by the controller 300 described above in some embodiments.
Figure 5 illustrates an example scenario according to an embodiment of the invention. The vehicle 100 is at a current state 510 which has a position Xi, yi and a heading Θ which is an angle . The angle Θ may be defined with respect to a predetermined reference which, in the example is coordinate system 500 defined by x and yaxis respectively. For clarity the angles in the example are also illustrated with respect to an origin of the x and y axes. It will be appreciated that all angles may be defined with respect to another reference, such as being determined with respect to the current heading of the vehicle 100 i.e. 0=0°. Step 410 comprises determining the current state 510 of the vehicle 110 i.e. determining the location and current heading θ of the vehicle 100. Step 410 may comprise the current state determining means 220 providing the signal indicative of the current state to the controller 210, 300. The current state determining means 220 may comprise a one or more devices for determining one or more of the current position, heading, velocity, and other parameters of the vehicle 100. The current position may be determined by a position determination device from received wireless signals, such as GPS or wireless communication signals. The heading may be determined by a heading determination device for determining the heading of the vehicle, such as the magnetometer, although it will be appreciated that the heading may be determined from a plurality of positions of the vehicle 100.
A desired state 520 of the vehicle 100 is indicated having a desired position x2, y2 and a desired heading 0d. A second desired state 530 is also illustrated for clarity, where the second desired state 530 lies along the desired trajectory at the desired heading 0d from the second state. A tangent of the desired trajectory is the desired heading angle 0d. Step 420 comprises determining at least one desired state 520 of the vehicle. In particular, step 420 comprises determining the desired position x2, y2 and desired heading 0d of the vehicle. Step 420 may comprise the desired state determining means 230 providing the signal indicative of the desired state of the vehicle 100 to the controller 210, 300.
In step 430 of the method 400 a heading correction β is determined. The heading correction is an angle between the current position of the vehicle and a desired position of the vehicle as illustrated in Figure 5. Given the current 510 and desired position 520 of the vehicle 100, the angle β may be calculated as:
β , (y-i- yu
B = atan -----\x2 — x J
Step 430 may be performed by the HCDM 310, where the HCDM 310 the parameter indicative of the heading correction output by the HCDM 310 is β and is provided as signal 313 to the MDHM 320.
In step 440 a modified desired heading 0d’ is determined. The modified desired heading 0d’ is determined as modified desired heading angle 0d’. The modified desired heading 0d’ is determined to reduce an error between the current and desired states 510, 520 of the vehicle. In particular, the desired heading 0d is modified to reduce the error between the current and desired positions of the vehicle 100. The modified desired heading 0d’ is based on the desired heading 0d to which is applied the heading correction β. In order to avoid excessive correct being applied, in some embodiments a gain factor g is used to apply a portion of the heading correction to the desired heading 0d. The gain factor g may be a value between 0 and 1.
In some embodiment, in step 440 the modified desired trajectory heading 0d’ is determined as:
= + 9β
In this way, the desired or target heading angle is modified to adopt a heading 540 as illustrated in Figure 5 which reduces a heading and positional error of the vehicle 100.
Taking for example the values:
0d = -12°;
= 10°;
β=50°.
If, as an example, a heading error 0e is calculated based on only the current and desired headings, the heading error 0e would be determined as:
9e = θα Which gives:
6e = -12 - 10 = -22°
However, in an embodiment of the invention, the desired heading 0d is modified as θ'α = θα + 9β
Which gives, assuming we consider a gain g=1:
θα' = -12 + 50 = 38°
It will be appreciated that g may assume values other than 1 as appropriate.
Step 440 may be performed by the MDHM 320 which outputs a signal 322 indicative of the modified desired heading, 0d’, as an output.
In step 450 the heading error 0e is determined. Step 450 may be performed by the HEDM 330. The heading error 0e is determined in dependence on signals 322, 331 and 332 as:
9e = θα' Which in the example is:
9e = 38 - 10 = 28°
The HEDM 330 is arranged to output a signal 333 indicative of the heading error.
The method 400 may comprise a step 460 of controlling the heading of the vehicle 100. The heading is controlled in dependence on the heading error signal 333. The heading of the vehicle may be controlled in some embodiments by steering the vehicle which may comprise controlling one or more actuators to control an angle of one or more steering wheels of the vehicle 100.
As noted above, in some embodiments, a plurality of desired states 140, 150, 160, 170, 180 of the vehicle may be determined, where each desired state may correspond to a respective future point in time. In such embodiments, a vector of desired future states may be formed. The vector of desired future states may be used to determine a plurality of heading error values; a heading error value for each desired state of the vehicle 100 described in the vector. Each heading error value is determined with respect to the current state of the vehicle 100. In some embodiments, each heading error value may be associated with a respective weighting, where the weighting decreases with increasing time from the current point in time. In this way, heading errors for increasing distant points in time are given less weight or importance.
In other embodiments, a motion predictive controller (MPC) may be used which predicts a heading of the vehicle at each of a plurality of future points in time in dependence on the current state of the vehicle. Thus a vector of predicted headings of the vehicle may be determined. The vector of predicted heading may be used in conjunction with the vector of desired future headings to determine a heading error value for each pair of future and desired state of the vehicle 100. With this method a complex control as is MPC can be simplified to run in a single state variable (heading)
Figure 6 illustrates a vehicle 600 according to an embodiment of the invention. The vehicle 600 is a wheeled vehicle arranged to be a land-going vehicle. The vehicle 600 is arranged to perform a method 400 according to an embodiment of the invention. The vehicle 600 may comprise a controller as illustrated in Figure 3. The vehicle 600 may comprise a system according to an embodiment of the invention a illustrated in Figure 2.
It will be appreciated that embodiments of the present invention can be realised in the form of hardware, software or a combination of hardware and software. Any such software may be stored in the form of volatile or non-volatile storage such as, for example, a storage device like a ROM, whether erasable or rewritable or not, or in the form of memory such as, for example, RAM, memory chips, device or integrated circuits or on an optically or magnetically readable medium such as, for example, a CD, DVD, magnetic disk or magnetic tape. It will be appreciated that the storage devices and storage media are embodiments of machinereadable storage that are suitable for storing a program or programs that, when executed, implement embodiments of the present invention. Accordingly, embodiments provide a program comprising code for implementing a system or method as claimed in any preceding claim and a machine readable storage storing such a program. Still further, embodiments of the present invention may be conveyed electronically via any medium such as a communication signal carried over a wired or wireless connection and embodiments suitably encompass the same.
All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.
Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.
The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed. The claims should not be construed to cover merely the foregoing embodiments, but also any embodiments which fall within the scope of the claims.

Claims (25)

1. A method of controlling a vehicle, comprising:
determining (430) a heading correction value indicative of a difference between a current trajectory of a vehicle and a desired trajectory of a vehicle;
determining (440) a modified desired heading for the vehicle in dependence on the heading correction value; and determining (460) one or more steering inputs for the vehicle in dependence on a current heading of the vehicle and the modified desired heading.
2. The method of claim 1, wherein the heading correction value is determined in dependence on a current position of the vehicle and a desired position of the vehicle.
3. The method of claim 2, wherein the heading correction value is determined as an angle between the current position of the vehicle and the desired position of the vehicle.
4. The method of claim 3, wherein the heading correction value β is determined as:
β = atan -----\x2 -x-J where Xi, yi are indicative of the current position of the vehicle and x2, y2are indicative of the desired position of the vehicle.
5. The method of any preceding claim, wherein the modified desired heading is determined in dependence on a desired heading of the vehicle and the heading correction value.
6. The method of claim 5, wherein the modified desired heading is determined by applying a gain factor to the heading correction value.
7. The method of claim 6, wherein the modified desired heading, 0d’, is determined as:
= ^α+9β where 0d is the desired heading of the vehicle, g is the gain factor and β is the heading correction value.
8. The method of any preceding claim, comprising determining a heading error in dependence on the modified desired heading and a current heading of the vehicle.
9. The method of claim 8, wherein the heading error, 0e, is determined as:
9e = θ/ where 0/ is the modified desired heading and Θ is the current heading of the vehicle.
10. The method of claim 8 or 9, wherein the one or more steering inputs for the vehicle are determined in dependence on the heading error.
11. A controller (210, 300), comprising:
current state input means (311,331) to receive a signal indicative of a current state of a vehicle;
desired state input means (312, 332) to receive a signal indicative of a desired state of a vehicle;
processing means (310, 320, 330) arranged to:
determine (430) a heading correction value indicative of a difference between a current trajectory of a vehicle and a desired trajectory of a vehicle;
determine (440) a modified desired heading for the vehicle in dependence on the heading correction value; and determine (460) one or more steering inputs for the vehicle in dependence on a current heading of the vehicle and the modified desired heading;
output means arranged to output a signal indicative of the one or more steering inputs for the vehicle.
12. The controller of claim 11, wherein:
the current state input means comprises first input means (311) arranged to receive a signal indicative of a current position of the vehicle;
the desired state input means comprises second input means (312) arranged to receive a signal indicative of a desired position of the vehicle; and the processing means is arranged to determine the heading correction value in dependence on the current position of the vehicle and the desired position of the vehicle.
13. The controller of claim 12, wherein the processing means is arranged to determine the heading correction value as an angle between the current position of the vehicle and the desired position of the vehicle.
14. The controller of claim 13, wherein the processing means is arranged to determine the heading correction value β as:
β = atan -----\x2 -x-J where xb yi are indicative of the current position of the vehicle and x2, y2are indicative of the desired position of the vehicle.
15. The controller of any of claims 11 to 14, wherein:
the desired state input means comprises a third input means (321) arranged to receive a signal indicative of a desired heading of the vehicle; and the processing means is arranged to determine modified desired heading in dependence on a desired heading of the vehicle and the heading correction value.
16. The controller of claim 15, wherein the processing means is arranged to determine the modified desired heading by applying a gain factor to the heading correction value.
17. The controller of claim 16, wherein the processing means is arranged to determine the modified desired heading, 0d’,as:
θα' = θά+ρβ where 0d is the desired heading of the vehicle, g is the gain factor and β is the heading correction value.
18. The controller of any of claims 11 to 17, wherein the processing means is arranged to determine a heading error in dependence on the modified desired heading and a current heading of the vehicle.
19. The controller of claim 18, wherein the processing means is arranged to determine the heading error, 6e, as:
9e = θ/ where θα' is the modified desired heading and 0 is the current heading of the vehicle.
20. The controller of claim 18 or 19, wherein the processing means is arranged to determine one or more steering inputs for the vehicle are determined in dependence on the heading error.
21. A system comprising:
the controller of any of claims 11 to 20;
control means arranged to receive the one or more signals indicative of the one or more steering inputs and to control the vehicle in dependence thereon.
22. The system of claim 21, wherein the control means comprises a steering control means for controlling a steering system of the vehicle.
23. A vehicle arranged to perform the method according to any of claims 1 to 10, comprising the controller of any of claims 11 to 20 or the system of claim 21 or 22.
24. Computer software which, when executed by a computer, is arranged to perform a method according to any of claims 1 to 10.
25. The computer software of claim 24 stored on a computer readable medium.
GB1809342.7A 2018-06-07 2018-06-07 Apparatus and method controlling a process Withdrawn GB2574448A (en)

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EP0273976A1 (en) * 1986-05-21 1988-07-13 Kabushiki Kaisha Komatsu Seisakusho Guiding apparatus for unmanned movable bodies
US20020165648A1 (en) * 2001-05-07 2002-11-07 Zeitler David W. AGV position and heading controller
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Publication number Priority date Publication date Assignee Title
GB2158965A (en) * 1984-05-16 1985-11-20 Gen Electric Co Plc Driverless vehicle
EP0236614A2 (en) * 1986-03-10 1987-09-16 Si Handling Systems, Inc. Automatic guided vehicle systems
EP0273976A1 (en) * 1986-05-21 1988-07-13 Kabushiki Kaisha Komatsu Seisakusho Guiding apparatus for unmanned movable bodies
US20020165648A1 (en) * 2001-05-07 2002-11-07 Zeitler David W. AGV position and heading controller
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