CN110949383B - Control method and device for following driving of automatic driving vehicle - Google Patents

Control method and device for following driving of automatic driving vehicle Download PDF

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CN110949383B
CN110949383B CN201811123598.8A CN201811123598A CN110949383B CN 110949383 B CN110949383 B CN 110949383B CN 201811123598 A CN201811123598 A CN 201811123598A CN 110949383 B CN110949383 B CN 110949383B
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vehicle
acceleration
front vehicle
instantaneous
state
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CN110949383A (en
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郑志晓
查鸿山
邱明喆
王晓波
林小敏
周文立
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Guangzhou Automobile Group Co Ltd
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Guangzhou Automobile Group Co Ltd
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    • 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
    • B60W30/14—Adaptive cruise control
    • B60W30/143—Speed control
    • B60W30/146—Speed limiting
    • 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
    • B60W30/02—Control of vehicle driving stability
    • B60W30/025—Control of vehicle driving stability related to comfort of drivers or passengers
    • 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
    • B60W40/10—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 vehicle motion
    • 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
    • B60W40/10—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 vehicle motion
    • B60W40/107—Longitudinal acceleration
    • 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
    • B60W2520/10—Longitudinal speed
    • 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
    • B60W2720/10—Longitudinal speed
    • B60W2720/106—Longitudinal acceleration

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  • Automation & Control Theory (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Mathematical Physics (AREA)
  • Control Of Driving Devices And Active Controlling Of Vehicle (AREA)

Abstract

The invention provides a control method and a device for following driving of an automatic driving vehicle, wherein the control method comprises the steps of obtaining the instantaneous speed of a front vehicle, the instantaneous speed of the vehicle and the actual relative distance between the vehicle and the front vehicle; acquiring the instantaneous acceleration of the front vehicle, and judging the running state of the front vehicle according to the instantaneous acceleration of the front vehicle; calculating the expected relative distance between the vehicle and the front vehicle according to the running state of the front vehicle and the instantaneous speed of the front vehicle; calculating the expected acceleration of the vehicle according to the parameters; and controlling the vehicle to run at the expected acceleration of the vehicle. The invention determines the driving state of the front vehicle by judging the acceleration of the front vehicle, sets different parameter values for the same parameter according to different driving states of the front vehicle to calculate the expected acceleration of the vehicle, and controls the driving of the vehicle according to the expected acceleration of the vehicle, thereby solving the problems of poor following safety and poor passenger experience under the conditions of overtaking, emergency braking and the like caused by the prior art.

Description

Control method and device for following driving of automatic driving vehicle
Technical Field
The invention relates to the technical field of automobile control, in particular to a control method and a control device for following driving of an automatic driving vehicle.
Background
Following driving is a basic function of automatic driving, and the motion control of the automatic driving vehicle meets the driving safety and considers the driving habit of a driver and the comfort brought to passengers as much as possible; the automatic driving following running control scheme provided by the prior art judges acceleration and deceleration based on the relative speed or relative distance between a front vehicle and a vehicle, ignores running state information provided by the acceleration of the front vehicle, does not meet following safety under the conditions of overtaking, emergency braking and the like, and does not consider passenger comfort.
Disclosure of Invention
In order to solve the technical problem, the invention provides a control method and a control device for following running of an automatic driving vehicle.
The invention provides a control method for following running of an automatic driving vehicle, which comprises the following steps:
acquiring the instantaneous speed of a front vehicle, the instantaneous speed of the vehicle and the actual relative distance between the vehicle and the front vehicle;
acquiring the instantaneous acceleration of a front vehicle, and judging the running state of the front vehicle according to the instantaneous acceleration of the front vehicle;
calculating the expected relative distance between the vehicle and the front vehicle according to the running state of the front vehicle and the instantaneous speed of the front vehicle;
calculating the expected acceleration of the vehicle according to the instantaneous speed of the vehicle, the actual relative distance and the expected relative distance between the vehicle and a front vehicle, and the instantaneous speed and the instantaneous acceleration of the front vehicle;
and controlling the vehicle to run at the expected acceleration of the vehicle.
Further, the step of acquiring the instantaneous acceleration of the preceding vehicle and determining the driving state of the preceding vehicle according to the instantaneous acceleration of the preceding vehicle specifically includes:
periodically acquiring the instantaneous acceleration of the front vehicle;
calculating the average acceleration of the front vehicle according to the instantaneous acceleration of the front vehicle acquired within the preset time, wherein the preset time is a multiple of the period;
and judging the running state of the front vehicle according to the value range of the average acceleration of the front vehicle.
Further, according to the value range of the average acceleration of the preceding vehicle, the specific steps of judging the running state of the preceding vehicle are as follows:
if the average acceleration of the front vehicle is larger than a first threshold value, judging that the front vehicle is in an acceleration running state;
if the average acceleration of the front vehicle is greater than or equal to a second threshold value and is smaller than or equal to the first threshold value, judging that the front vehicle is in a constant-speed running state;
if the average acceleration of the front vehicle is greater than or equal to a third threshold value and is smaller than the second threshold value, judging that the front vehicle is in a deceleration running state;
and if the average acceleration of the front vehicle is smaller than the third threshold value, judging that the front vehicle is in a deceleration braking state.
Further, the first threshold is a product of a first judgment threshold coefficient and the gravitational acceleration, and the value range of the first judgment threshold coefficient is 0-0.05; the second threshold value is the product of a second judgment threshold value coefficient and the gravity acceleration, and the value range of the second judgment threshold value coefficient is-0.05-0; the third threshold is the product of a third judgment threshold coefficient and the gravity acceleration, and the value range of the third judgment threshold coefficient is-0.5 to-0.3.
Further, the expected relative distance between the host vehicle and the front vehicle is calculated according to the following formula:
ddes＝(1.5+λ)vp+d0；
wherein d isdesIs the desired relative distance, v, of the host vehicle from the front vehiclepInstantaneous speed of the preceding vehicle, d0The relative distance between the vehicle and the front vehicle when the vehicle is completely stopped, d0Has a value range of [5.0m, 6.0m]；
When the front vehicle is in an acceleration driving state, the lambda value is [ -0.5, -0.1);
when the front vehicle is in a constant-speed running state, the value of lambda is [ -0.1, 0.1);
when the front vehicle is in a deceleration running state, the value of lambda is [0.1, 0.2);
when the front vehicle is in a deceleration braking state, the lambda value is [0.2, 0.5 ].
Further, the specific steps of calculating the desired acceleration of the host vehicle are as follows:
establishing a system state equation according to two state quantities, wherein the two state quantities comprise: the difference between the actual relative distance and the expected relative distance between the vehicle and the front vehicle and the difference between the instantaneous speeds of the vehicle and the front vehicle;
selecting weight coefficients with a certain proportional relation as coefficients of three state quantities respectively to establish a control index equation, wherein the three state quantities comprise: the difference between the actual relative distance and the expected relative distance between the vehicle and the front vehicle, the difference between the instantaneous speeds of the vehicle and the front vehicle and the expected acceleration of the vehicle;
according to a system state equation and a control index equation, constructing a function to solve the optimal steady-state error caused by the expected acceleration of the vehicle and the instantaneous acceleration of the front vehicle;
and obtaining the expected acceleration of the vehicle according to the optimal steady-state error caused by the expected acceleration of the vehicle and the instantaneous acceleration of the front vehicle.
Further, the specific step of limiting the expected acceleration of the vehicle is as follows:
limiting the desired acceleration of the host vehicle to a first acceleration when the desired acceleration of the host vehicle is greater than the first acceleration;
when the desired acceleration of the host vehicle is smaller than the second acceleration, the desired acceleration of the host vehicle is limited to the second acceleration.
The invention provides a control device for following running of an automatic driving vehicle, which comprises:
the detection unit is used for acquiring the instantaneous speed and the instantaneous acceleration of the front vehicle, the instantaneous speed of the vehicle and the actual relative distance between the vehicle and the front vehicle;
the judging unit is used for judging the running state of the front vehicle according to the instantaneous acceleration of the front vehicle;
the first calculation unit is used for calculating the expected relative distance between the vehicle and the front vehicle according to the running state of the front vehicle and the instantaneous speed of the front vehicle;
a second calculation unit for calculating an expected acceleration of the host vehicle from the instantaneous speed of the host vehicle, the actual relative distance and the expected relative distance between the host vehicle and the preceding vehicle, and the instantaneous speed and the instantaneous acceleration of the preceding vehicle;
a control unit configured to control a host vehicle to travel at a desired acceleration of the host vehicle.
Further, the detection unit is specifically configured to periodically acquire an instantaneous acceleration of the preceding vehicle; the judging unit is specifically used for calculating the average acceleration of the front vehicle according to the instantaneous acceleration of the front vehicle acquired within the preset time, wherein the preset time is a multiple of the period; and judging the running state of the front vehicle according to the value range of the average acceleration of the front vehicle.
The implementation of the invention has the following beneficial effects:
the method and the device judge the driving state of the front vehicle by acquiring the acceleration of the front vehicle, set different values for the same parameters according to the driving state of the front vehicle, fully consider the state of the front vehicle for the calculated expected acceleration of the vehicle, provide a safer solution for the front vehicle or the front vehicle in a braking state, consider passenger comfort and experience, limit the acceleration of the vehicle to a certain extent under special conditions such as braking and deceleration of the non-front vehicle, avoid repeated acceleration and deceleration of the vehicle, and solve the problems of unsafety during overtaking and front vehicle braking and poor passenger experience in the automatic driving following condition caused by the prior art.
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In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a flowchart of a control method for following driving of an autonomous vehicle according to an embodiment of the present invention.
Fig. 2 is a structural diagram of a control device for following travel of an autonomous vehicle according to an embodiment of the present invention.
Detailed Description
The core content of the patent is to judge the driving state of the preceding vehicle according to the acceleration of the preceding vehicle, and make a decision on the acceleration of the vehicle based on the driving state of the preceding vehicle and other parameters, and the following will further explain the specific implementation of the method and the system in conjunction with the drawings and the embodiments.
The following describes an embodiment of a control method and device for following driving of an autonomous vehicle according to the present invention in detail.
As shown in fig. 1, an embodiment of the present invention provides a control method for following driving of an autonomous vehicle, where the control method includes:
and step S101, acquiring the instantaneous acceleration of the front vehicle, the instantaneous speed of the vehicle and the actual relative distance between the vehicle and the front vehicle.
In this embodiment, the instantaneous acceleration of the preceding vehicle, the instantaneous speed of the vehicle, and the actual relative distance between the vehicle and the preceding vehicle, which are obtained by radar, sensor, and the like, are obtained, the relative distance between the vehicle head and the preceding vehicle is the distance between the vehicle head and the vehicle tail of the preceding vehicle, and the actual relative distance is the distance between the vehicle head and the vehicle tail of the preceding vehicle, which is obtained by measurement.
And S102, acquiring the instantaneous acceleration of the front vehicle, and judging the running state of the front vehicle according to the instantaneous acceleration of the front vehicle.
In this embodiment, the driving state of the leading vehicle includes four states, i.e., an acceleration driving state, a constant speed driving state, a deceleration driving state, and a deceleration braking state, which can also be divided in more detail according to actual needs.
In the embodiment, the running state of the front vehicle is judged through the acceleration of the front vehicle, so that a judgment basis of different values of the same parameter is provided for the acceleration calculation of the vehicle in the later period; there are two ways to judge the driving state of the front vehicle according to the instantaneous acceleration of the front vehicle: one way is to judge according to the instantaneous acceleration of the current front vehicle, but the judging way has the defects that when the driving state changes, the judgment is carried out according to the instantaneous acceleration of the front vehicle, and wrong information can be brought to the following calculation; the other mode is that a series of instantaneous accelerations of the front vehicle in a short time are averaged, so that the obtained average acceleration can reflect the real running state of the front vehicle; another embodiment is specifically as follows:
the method includes the steps that instantaneous acceleration of a front vehicle is periodically acquired and stored in a memory time window, the acquired time period is T, the value of T is any one value from 0.01s to 0.1s, it needs to be noted that the storage in the memory time window is an optional mode and can also be stored or memorized in other modes, and the memory time window is a storage space.
Calculating the average acceleration of the front vehicle according to the instantaneous acceleration of the front vehicle acquired within the preset time, wherein the preset time is a multiple of a cycle, for example, the average acceleration av is calculated by calling the instantaneous acceleration of n continuous front vehicles within a memory time window,
Figure RE-GDA0001956432870000051
a is atFor memorizing the instantaneous acceleration of the last preceding vehicle in the window, the preset time is nT, which is greater than or equal to 0.5 s.
Further judging the running state of the front vehicle according to the value range of the average acceleration of the front vehicle, and the specific steps are as follows:
if the average acceleration of the front vehicle is larger than a first threshold value, judging that the front vehicle is in an acceleration running state;
if the average acceleration of the front vehicle is greater than or equal to a second threshold value and is smaller than or equal to the first threshold value, judging that the front vehicle is in a constant-speed running state;
if the average acceleration of the front vehicle is greater than or equal to a third threshold value and is smaller than the second threshold value, judging that the front vehicle is in a deceleration running state;
if the average acceleration of the front vehicle is smaller than the third threshold value, the front vehicle is judged to be in a deceleration braking state;
the first threshold is the product of a first judgment threshold coefficient and the gravity acceleration, and the value range of the first judgment threshold coefficient is 0-0.05; the second threshold value is the product of a second judgment threshold value coefficient and the gravity acceleration, and the value range of the second judgment threshold value coefficient is-0.05-0; the third threshold is the product of a third judgment threshold coefficient and the gravity acceleration, and the value range of the third judgment threshold coefficient is-0.5 to-0.3.
To understand the process of determining the driving state of the preceding vehicle more easily, a practical example is specifically described, and av is the average acceleration of the preceding vehicle:
when av > ka1g, judging that the front vehicle is in an acceleration running state;
when k isa2g≤av≤ka1g, judging that the front vehicle is in a constant-speed running state;
when k isa3g≤av＜ka2g, judging that the front vehicle is in a deceleration running state;
when av < ka3g, judging that the front vehicle is in a deceleration braking state;
k isa1g、ka3g and ka2g corresponds to the first, second and third threshold values, ka1、ka2And ka3Respectively a first judgment threshold, a second judgment threshold and a third judgment threshold, k, of the front vehiclea1Has a value range of [0, 0.05 ]]，ka2Has a value range of [ -0.05, 0 [)]，ka3Has a value range of [ -0.5, -0.3 [)]G is the gravity acceleration and takes a value of 9.8m/s2And determining the value range of the average acceleration of the front vehicle according to the first threshold, the second threshold and the third threshold.
And step S103, calculating the expected relative distance between the vehicle and the front vehicle according to the running state of the front vehicle and the instantaneous speed of the front vehicle.
It should be noted that, according to the related documents, in order to ensure the driving safety, the following distance should not be less than 1.4vp， vpFor the instantaneous speed of the preceding vehicle, even if the automatic driving is more responsive than the human control, it should not be below this distance or maintain a certain safety distance, since the emergency braking will also cause a bad body to the passengersAnd (6) testing.
In the embodiment, the expected relative distance between the vehicle and the front vehicle is calculated according to the following formula according to the running state of the front vehicle and the instantaneous speed of the front vehicle:
ddes＝(1.5+λ)vp+d0；
d isdesThe desired relative distance between the vehicle and the front vehicle, vpInstantaneous speed of the preceding vehicle, d0The relative distance between the vehicle and the front vehicle when the vehicle is completely stopped, d0The value range is [5.0m, 6.0m]；
When the front vehicle is in an acceleration driving state, the lambda value is [ -0.5, -0.1);
when the front vehicle is in a constant-speed running state, the value of lambda is [ -0.1, 0.1);
when the front vehicle is in a deceleration running state, the value of lambda is [0.1, 0.2);
when the front vehicle is in a deceleration braking state, the lambda value is [0.2, 0.5 ].
And step S104, calculating the expected acceleration of the vehicle according to the instantaneous speed of the vehicle, the actual relative distance and the expected relative distance between the vehicle and the front vehicle, and the instantaneous speed and the instantaneous acceleration of the front vehicle.
It should be noted that the step of solving the desired acceleration of the host vehicle is:
establishing a system state equation according to two state quantities, wherein the two state quantities comprise the difference between the actual relative distance and the expected relative distance between the vehicle and the front vehicle and the difference between the instantaneous speeds of the vehicle and the front vehicle;
selecting weight coefficients with a certain proportional relation as coefficients of three state quantities respectively to establish a control index equation, wherein the three state quantities comprise: the difference between the actual relative distance and the expected relative distance between the vehicle and the front vehicle, the difference between the instantaneous speeds of the vehicle and the front vehicle and the expected acceleration of the vehicle;
according to a system state equation and a control index equation, constructing a function to solve the optimal steady-state error caused by the expected acceleration of the vehicle and the instantaneous acceleration of the front vehicle;
and obtaining the expected acceleration of the vehicle according to the optimal steady-state error caused by the expected acceleration of the vehicle and the instantaneous acceleration of the front vehicle.
In this embodiment, the step of further solving for the desired acceleration of the host vehicle specifically includes:
according to the state quantity x ═ d-ddes v-vp]TEstablishing a system equation of state
Figure RE-GDA0001956432870000071
D is the actual relative distance between the vehicle and the preceding vehicle, v is the instantaneous speed of the vehicle, a is the expected acceleration of the vehicle, and apInstantaneous acceleration of the front vehicle;
setting up
Figure RE-GDA0001956432870000072
Selecting a weight coefficient q1、q2And r as state quantities d-d, respectivelydes、v-vpAnd a coefficient of a, set to 8q2≤q1≤15q2,r＝q2Obtaining a control index
Figure RE-GDA0001956432870000073
Namely, it is
Figure RE-GDA0001956432870000074
Wherein
Figure RE-GDA0001956432870000075
In addition, q is1As d-ddesCoefficient of (a), q2As v-vpThe coefficient r is the coefficient of a;
constructing a Hamiltonian:
Figure RE-GDA0001956432870000076
introducing a parameter P, setting the control index to reach the minimum value,
Figure RE-GDA0001956432870000077
said J*For optimal value of J, P is given by the equation
Figure RE-GDA0001956432870000078
Solving to obtain;
derived from extreme conditions
Figure RE-GDA0001956432870000079
Find a*(t)＝-r-1(t)BT(t) P (t) x (t), said a*(t) an optimal desired acceleration of the host vehicle;
setting K as r-1(t)BT(t)P(t)＝[k1k2]Obtaining the optimal expected acceleration of the vehicle as a*(t) — kx (t), said k1Is (d-d)des) Gain of (k)2Is (v-v)p) A gain of (d);
according to apObtain feedback afeedback＝ap(1-k2(lambda-1)), said afeedbackFor eliminating apThe resulting steady state error;
according to the optimal expected acceleration a of the vehicle*(t) and afeedbackThe expected acceleration a of the vehicle is obtained*(t)+afeedback＝-k1(d-ddes)-k2(v-vp)+ap(1-k2(λ-1))。
And a step S105 of controlling the vehicle to run at the desired acceleration of the vehicle according to the desired acceleration of the vehicle.
In the present embodiment, the above steps can achieve safety of passing and sudden braking of the preceding vehicle in the following situation, and limit the expected acceleration of the own vehicle to a greater extent in order to further improve user comfort, but the safety issue is prioritized when the preceding vehicle is in the decelerating braking state, and the limit of the expected acceleration of the own vehicle is performed when the preceding vehicle is in any one of the accelerating running state, the constant speed running state, and the decelerating running state, without performing an operation of limiting the expected acceleration of the own vehicle.
Specifically, when the desired acceleration of the host vehicle is greater than the first acceleration, the desired acceleration of the host vehicle is limited to the first acceleration, when the desired acceleration of the host vehicle is less than the second acceleration, the desired acceleration of the host vehicle is limited to the second acceleration, and when the desired acceleration of the host vehicle is equal to or less than the first acceleration and equal to or greater than the second acceleration, the existing state is maintained; the first acceleration is positive and the second acceleration is negative. For example, the first acceleration is 1.5m/s2The second acceleration is-2.0 m/s2(ii) a If the vehicle is not in the deceleration braking state, the acceleration is limited to the first acceleration when the vehicle is accelerated too fast, and the deceleration is limited to the second acceleration when the vehicle is decelerated too fast; further for the convenience of the driver and the passengers, the first acceleration and the second acceleration can be manually adjusted and changed, and the purpose is to set according to the body states of different passengers in the automatic driving state, so that the passengers are not accelerated or decelerated too fast, and the comfort of passengers is reduced.
As shown in fig. 2, an embodiment of the present invention provides a control apparatus for following travel of an autonomous vehicle, including:
a detection unit 21 for acquiring an instantaneous speed and an instantaneous acceleration of the preceding vehicle, an instantaneous speed of the own vehicle, and an actual relative distance between the own vehicle and the preceding vehicle;
a judging unit 22 for judging the running state of the preceding vehicle based on the instantaneous acceleration of the preceding vehicle;
a first calculation unit 23 for calculating an expected relative distance between the own vehicle and the preceding vehicle based on a preceding vehicle running state and an instantaneous speed of the preceding vehicle;
a second calculation unit 24 for calculating an expected acceleration of the host vehicle based on the instantaneous speed of the host vehicle, the actual relative distance and the expected relative distance of the host vehicle and the preceding vehicle, and the instantaneous speed and the instantaneous acceleration of the preceding vehicle;
a control unit 25 for controlling the host vehicle to travel at a desired acceleration of the host vehicle.
Further, the detection unit 21 is specifically configured to periodically acquire an instantaneous acceleration of the preceding vehicle; the determining unit 22 is specifically configured to calculate an average acceleration of the preceding vehicle according to an instantaneous acceleration of the preceding vehicle obtained within a preset time, where the preset time is a multiple of a cycle; and judging the running state of the front vehicle according to the value range of the average acceleration of the front vehicle.
The implementation of the invention has the following beneficial effects:
the method and the device judge the driving state of the front vehicle by acquiring the acceleration of the front vehicle, set different values for the same parameters according to the driving state of the front vehicle, fully consider the state of the front vehicle for the calculated expected acceleration of the vehicle, provide a safer solution for the front vehicle or the front vehicle in a braking state, consider passenger comfort and experience, limit the acceleration of the vehicle to a certain extent as much as possible under special conditions such as braking and deceleration of the non-front vehicle, avoid repeated acceleration and deceleration of the vehicle, and solve the problems of unsafety during overtaking and front vehicle braking and poor passenger experience under the condition of automatic driving and vehicle following caused by the prior art.
The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. For those skilled in the art to which the invention pertains, several simple deductions or substitutions can be made without departing from the spirit of the invention, and all shall be considered as belonging to the protection scope of the invention.

Claims (6)

1. A control method for following travel of an autonomous vehicle, characterized by comprising:
acquiring the instantaneous speed of a front vehicle, the instantaneous speed of the vehicle and the actual relative distance between the vehicle and the front vehicle;
periodically acquiring the instantaneous acceleration of the front vehicle; calculating the average acceleration of the front vehicle according to the instantaneous acceleration of the front vehicle acquired within the preset time, wherein the preset time is a multiple of the period;
if the average acceleration of the front vehicle is larger than a first threshold value, judging that the front vehicle is in an acceleration running state; if the average acceleration of the front vehicle is greater than or equal to a second threshold value and is smaller than or equal to the first threshold value, judging that the front vehicle is in a constant-speed running state; if the average acceleration of the front vehicle is greater than or equal to a third threshold value and is smaller than the second threshold value, judging that the front vehicle is in a deceleration running state; if the average acceleration of the front vehicle is smaller than the third threshold value, the front vehicle is judged to be in a deceleration braking state;
calculating the expected relative distance between the vehicle and the front vehicle according to the following formula according to the running state of the front vehicle and the instantaneous speed of the front vehicle:
ddes＝(1.5+λ)vp+d0
wherein d isdesIs the desired relative distance, v, of the host vehicle from the front vehiclepInstantaneous speed of the preceding vehicle, d0The distance between the vehicle and the front vehicle when the vehicle is completely parked is within the range of 5.0m and 6.0m](ii) a When the front vehicle is in an acceleration driving state, the lambda value is [ -0.5, -0.1); when the front vehicle is in a constant-speed running state, the value of lambda is [ -0.1, 0.1); when the front vehicle is in a deceleration running state, the value of lambda is [0.1, 0.2); when the front vehicle is in a deceleration braking state, the value of lambda is [0.2, 0.5]]；
Calculating the expected acceleration of the vehicle according to the instantaneous speed of the vehicle, the actual relative distance and the expected relative distance between the vehicle and a front vehicle, and the instantaneous speed and the instantaneous acceleration of the front vehicle;
and controlling the vehicle to run at the expected acceleration of the vehicle.
2. The control method according to claim 1, wherein the first threshold is a product of a first judgment threshold coefficient and the gravitational acceleration, and the value range of the first judgment threshold coefficient is 0-0.05; the second threshold value is the product of a second judgment threshold value coefficient and the gravity acceleration, and the value range of the second judgment threshold value coefficient is-0.05-0; the third threshold is the product of a third judgment threshold coefficient and the gravity acceleration, and the value range of the third judgment threshold coefficient is-0.5 to-0.3.
3. The control method according to claim 1, wherein the calculating the desired acceleration of the host vehicle includes:
establishing a system state equation according to two state quantities, wherein the two state quantities comprise: the difference between the actual relative distance and the expected relative distance between the vehicle and the front vehicle and the difference between the instantaneous speeds of the vehicle and the front vehicle;
selecting weight coefficients with a certain proportional relation as coefficients of three state quantities respectively to establish a control index equation, wherein the three state quantities comprise: the difference between the actual relative distance and the expected relative distance between the vehicle and the front vehicle, the difference between the instantaneous speeds of the vehicle and the front vehicle and the expected acceleration of the vehicle;
according to a system state equation and a control index equation, constructing a function to solve the optimal steady-state error caused by the expected acceleration of the vehicle and the instantaneous acceleration of the front vehicle;
and obtaining the expected acceleration of the vehicle according to the optimal steady-state error caused by the expected acceleration of the vehicle and the instantaneous acceleration of the front vehicle.
4. The control method according to claim 1, characterized by further comprising:
when the current vehicle running state is any one of an acceleration running state, a constant speed running state and a deceleration running state, the expected acceleration of the vehicle is subjected to amplitude limiting processing.
5. The control method according to claim 4, wherein the step of limiting the desired acceleration of the host vehicle comprises:
limiting the desired acceleration of the host vehicle to a first acceleration when the desired acceleration of the host vehicle is greater than the first acceleration;
when the desired acceleration of the host vehicle is smaller than the second acceleration, the desired acceleration of the host vehicle is limited to the second acceleration.
6. A control device for following travel of an autonomous vehicle, characterized by comprising:
the detection unit is used for acquiring the instantaneous speed of the front vehicle and periodically acquiring the instantaneous acceleration of the front vehicle, the instantaneous speed of the vehicle and the actual relative distance between the vehicle and the front vehicle;
the judging unit is used for calculating the average acceleration of the front vehicle according to the instantaneous acceleration of the front vehicle acquired within the preset time, wherein the preset time is a multiple of the period; the system is also used for judging that the front vehicle is in an acceleration running state when the average acceleration of the front vehicle is greater than a first threshold value; when the average acceleration of the front vehicle is greater than or equal to a second threshold value and is smaller than or equal to the first threshold value, judging that the front vehicle is in a constant-speed running state; when the average acceleration of the front vehicle is greater than or equal to a third threshold value and is smaller than the second threshold value, judging that the front vehicle is in a deceleration running state; when the average acceleration of the front vehicle is smaller than the third threshold value, judging that the front vehicle is in a deceleration braking state;
a first calculation unit for calculating an expected relative distance between the host vehicle and the preceding vehicle according to the following formula according to the driving state of the preceding vehicle and the instantaneous speed of the preceding vehicle:
ddes＝(1.5+λ)vp+d0
wherein d isdesIs the desired relative distance, v, of the host vehicle from the front vehiclepInstantaneous speed of the preceding vehicle, d0The distance between the vehicle and the front vehicle when the vehicle is completely parked is within the range of 5.0m and 6.0m](ii) a When the front vehicle is in an acceleration driving state, the lambda value is [ -0.5, -0.1); when the front vehicle is in a constant-speed running state, the value of lambda is [ -0.1, 0.1); when the front vehicle is in a deceleration running state, the value of lambda is [0.1, 0.2); when the front vehicle is in a deceleration braking state, the value of lambda is [0.2, 0.5]]；
A second calculation unit for calculating an expected acceleration of the host vehicle from the instantaneous speed of the host vehicle, the actual relative distance and the expected relative distance between the host vehicle and the preceding vehicle, and the instantaneous speed and the instantaneous acceleration of the preceding vehicle;
a control unit configured to control a host vehicle to travel at a desired acceleration of the host vehicle.
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