Adaptive layered hierarchical path tracking control method of automatic driving automobile

A technology of path tracking and automatic driving, applied in the direction of adaptive control, general control system, control/regulation system, etc., can solve the problem of not considering the time-varying characteristics of road friction conditions

Inactive Publication Date: 2017-12-19
SHANDONG COMP SCI CENTNAT SUPERCOMP CENT IN JINAN
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  • Abstract
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  • Application Information

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Problems solved by technology

However, the previous research methods usually did not consider the instantaneous wheel slip rate and the time-varying characteristics of road friction conditions, and a large number of model simplifications often ignored the inherent nonlinear coupling characteristics of the model itself. Under the first-order control framework, the nonlinearity of the vehicle dynamics model, the time-varying characteristics of overdrive and road conditions, and the multi-scale characteristics of vehicle body dynamics and wheel dynamics are integrated to realize real-time control of the dynamics of autonomous vehicles.

Method used

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  • Adaptive layered hierarchical path tracking control method of automatic driving automobile
  • Adaptive layered hierarchical path tracking control method of automatic driving automobile
  • Adaptive layered hierarchical path tracking control method of automatic driving automobile

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Experimental program
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Effect test

Embodiment 1

[0147] According to the path tracking control target of the self-driving car, the vehicle revolves around the reference path curvature center CP and the tangent velocity is v 0 The ideal state selection of is shown in formula (10):

[0148] x d =[0 0 v 0 ρ ref 0 0] T (10)

[0149] Among them, v 0 is the constant velocity, ρ ref For tracking curvature, define the path tracking error e=x-x d , the error dynamic equation is formula (11):

[0150]

[0151] Design the upper controller as formula (12):

[0152] u c =-Ke-Γ (12)

[0153] in, Then the error dynamics is formula (13):

[0154]

[0155] Choose K such that A 0 =A-BK is Hurwitz matrix, when u=u c When , the equilibrium point of formula (13) is uniformly exponentially stable.

Embodiment 2

[0157] The cost function J(t,S) of the middle layer controller in step f) Ldj ,S Sdj ) is selected as shown in formula (14):

[0158]

[0159] Among them, W u is a positive definite weight matrix, and at the same time, p i and q i is a normal number. S Lmin , S Lmax , S Smin , and S Smax is the limiting value of the wheel slip rate amplitude; based on formula (9) and formula (12), the adaptive law of dynamic optimization of wheel slip rate is equation (15):

[0160]

[0161] The friction parameter adaptation law is Equation (16):

[0162]

[0163] Among them, Γ l =diag(γ lj ), Γ k =diag(γ kj ), W h >0, and at the same time,

[0164]

[0165]

[0166]

[0167] Then the closed-loop system is at the equilibrium point is uniformly asymptotically stable.

[0168] Therefore, the optimization algorithm based on the middle layer controller can realize the dynamic optimization of the longitudinal and lateral slip ratio of the wheel, and identify the fr...

Embodiment 3

[0170] The horizontal quarter vehicle model of the lower controller in step f) is shown in formula (17):

[0171]

[0172] Based on the definition of wheel slip ratio, formula (5) is differentiated, and the formula The wheel slip rate dynamic equation (19) is obtained:

[0173]

[0174] in,

[0175]

[0176]

[0177]

[0178] When the wheel slip angle α j When small, cosα j ≈1; and when v yj , S Sj are small, v yj S Sj and can be approximately 0; at the same time, When , based on the truncated Taylor series expansion, the wheel slip rate dynamic equation is shown in formula (20):

[0179]

[0180] in, S Ldj , S Sdj is the ideal value of wheel slip ratio,

[0181] definition The dynamic equation (21) of wheel longitudinal slip rate error can be obtained as:

[0182]

[0183] when k j When unknown, the friction parameter adaptive law and the deterministic equivalent control law are shown in formula (22):

[0184]

[0185] in, S...

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Abstract

The invention provides an adaptive layered hierarchical path tracking control method of an automatic driving automobile. The method comprises following steps of a), establishing a rectangular coordinate system of an automobile body; b), establishing a path tracking control system model; c), establishing a frictional force model between tires and the road face; d), establishing a wheel slippage ration equation; e), establishing a control model; and f), establishing an adaptive layered hierarchical control framework. The adaptive layered hierarchical framework comprises an upper layer controller, a middle layer controller and a lower layer controller. According to the invention, through control objectives of stabilization, optimization, parameter estimation and the like, a path tracking control problem of the automatic driving automobile is solved; the wheel united slippage ratio is dynamically optimized; the sideslip of the wheels is restrained; proper distribution of tire force and torque of an over-actuation vehicle is achieved; brake control and frictional parameter estimation of independent wheels under unknown and non-symmetrical road face friction conditions are achieved; convergence of the frictional parameters is ensured; and ideal path tracking control of the automatic driving automobile is achieved.

Description

technical field [0001] The invention relates to the technical field of automatic driving vehicles, in particular to an adaptive hierarchical path tracking control method for automatic driving vehicles. Background technique [0002] With the development of intelligent transportation systems, the problem of path tracking control of autonomous vehicles has attracted much attention, and has been widely used in mobile robots and automatic parking systems. At the same time, many new vehicle path tracking control systems have emerged , these control systems are integrated a large number of control algorithms, such as PID control, linear quadratic control, sliding mode control and so on. However, the previous research methods usually did not consider the instantaneous wheel slip rate and the time-varying characteristics of road friction conditions, and a large number of model simplifications often ignored the inherent nonlinear coupling characteristics of the model itself. Under th...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G05B13/04
CPCG05B13/042
Inventor 陈长芳舒明雷杨媛媛魏诺杨明刘瑞霞孔祥龙
Owner SHANDONG COMP SCI CENTNAT SUPERCOMP CENT IN JINAN
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