Table Of ContentROBUST PATH FOLLOWING CONTROL FOR
INDEPENDENTLY ACTUATED
AUTONOMOUS GROUND VEHICLES WITH
TRANSIENT PERFORMANCE
IMPROVEMENT
ROBUST PATH FOLLOWING CONTROL FOR
INDEPENDENTLY ACTUATED AUTONOMOUS GROUND
VEHICLES WITH TRANSIENT PERFORMANCE
IMPROVEMENT
BY
CHUAN HU, B. ENG., M. ENG.
a thesis
submitted to the department of mechanical engineering
and the school of graduate studies
of mcmaster university
in partial fulfilment of the requirements
for the degree of
Ph.D. of Mechanical Engineering
McMaster University © Copyright by Chuan Hu, June 2017
All Rights Reserved
Ph.D. of Mechanical Engineering (2017) McMaster University
(Mechanical Engineering) Hamilton, Ontario, Canada
TITLE: ROBUST PATH FOLLOWING CONTROL FOR
INDEPENDENTLY ACTUATED AUTONOMOUS
GROUND VEHICLES WITH TRANSIENT PERFOR-
MANCE IMPROVEMENT
AUTHOR: Chuan Hu
M. Eng., (Vehicle Operation Engineering)
China Academy of Railway Sciences, Beijing, China
B. Eng., (Automotive Engineering)
Tsinghua University, Beijing, China
SUPERVISOR: Prof. Fengjun Yan
NUMBER OF PAGES: xxxv, 202
ii
To my parents, for their unconditional love and support.
Lay Abstract
This thesis focuses on the constraint control in the path following of autonomous
groundvehicleswithtransientperformanceimprovement, wherethesystemuncer-
tainties, external disturbances and input saturations have been considered. The
constraint control is used to constrain the path following errors in the safety re-
gions, and the transient control is used to improve the transient performance. The
ultimate control objective is to increase the path following accuracy and conver-
gence speed, and thus to improve the vehicle stability, safety and ride comfort.
This thesis proposed a novel desired-heading amendment to modify the traditional
path following model to reduce the system overshoot, a novel output constraint
strategy to constrain the lateral offset in reasonable bound, and two novel non-
linear control strategies to improve the transient performance. Also, experiments
were conducted to verify the effectiveness of the differential drive assisted steering.
iv
Abstract
This thesis addresses the path following control of independently actuated (IA)
autonomous ground vehicles (AGVs), and focuses on the constraint control and
transient performance improvement. The control aim is to inhibit overshoots and
eliminate steady-state errors in path following manoeuvres, and thus to reduce
the possibilities of AGVs to surpass safe driving bounds. Centering on this focus,
this thesis proposes a novel path-following modeling method, a novel output con-
straint control approach, and two novel nonlinear control strategies for transient
performance improvement. The contributions of this study lie on the following
five aspects: 1) A novel definition for the desired heading is proposed using the
sideslip-angle compensation, to reduce the steady-state errors in path following
caused by the non-zero sideslip-angle and the large/changing path curvature; 2) A
novel output constraint control approach using hyperbolic projection technique is
proposed to compactly restrain the lateral offset, and thus to prevent the vehicle
from surpassing safe lanes; 3) A novel integral sliding mode (ISM)-based com-
posite nonlinear feedback (CNF) technique is proposed to improve the transient
performance of path following, considering the system uncertainties, disturbances
and actuator saturations; 4) A novel disturbance observer-based CNF technique
is proposed to improve the transient performance for path following with differen-
tial drive assisted steering (DDAS) when the active steering system is in complete
failure. Corresponding comparative simulations based on CarSim-Simulink were
v
conducted to verify the proposed modeling and control strategies in 1)-4); 5) Ex-
periments have been conducted to verify the existence and effectiveness of the
DDAS mechanism.
vi
Acknowledgements
Firstly, I would like to express my great gratitude to my supervisor, Prof. Fengjun
Yan, for his sustainable guidance and training throughout my Ph.D. program.
With the speciality on control theory and vehicle engineering, he brought me into
the research world of vehicle dynamics and control, where I found the research
pleasure and achievability. Under his sagacious enlightenment and effective super-
vision, I have gradually acquired how to do research, make my own contributions,
and write academic papers. His support is just like a lamp guiding me in darkness
and encouraging me to overcome obstacles and pursue an academic career .
Secondly, I am very grateful to Prof. Rongrong Wang from Southeast Univer-
sity, China, for his wise comments and valuable counselling for my research work.
He began to guide and collaborate with me from the summer of 2014. Since then,
I had learned a great deal of knowledge from his academic wisdom and experience
on vehicle dynamics and control, CarSim simulation, and paper writing. I had
obtained several inspirations from the discussions with him, which enabled me to
publish several papers on top journals in my research field. Also, I would like to
thank Prof. Jinxiang Wang and Mr. Yunke Shi, who are in Prof. Wang’s research
group at Southeast University. I really appreciate their time and effort of helping
me in the experiments of the differential steering.
Thirdly, I would like to thank my parents and my elder sister, for their love
and support throughout my Ph.D. study.
vii
Abbreviations
ABS Antilock braking systems.
AFS Active front-wheel steering.
AGV Autonomous ground vehicle.
BMI Bilinear matrix inequality.
CG Center of gravity.
CNF Composite nonlinear feedback.
DDAS Differential drive assisted steering.
DoF Degrees of freedom.
DYC Direct yaw-moment control.
FDB Feedback dominance backstepping.
FWIA Four-wheel independently actuated.
HFDB Hyperbolic projection-based feedback dominance backstepping.
IA Independently actuated.
IAE Integral of absolute-value of error.
ISM Integral sliding mode.
ISV Integral of the square value.
ITAE Integral of time-multiplied absolute-value of error.
LDA lane-departure avoidance.
viii
LMI Linear matrix inequalities.
LQR Linear quadratic regulator.
MIMO Multi-input multi-output.
MPC Model predictive control.
PI Proportion integration.
PID Proportion integration differentiation.
SbW Steer-by-wire.
SMC Sliding mode control.
STA Super-twisting algorithm.
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Description:ground vehicles with transient performance improvement, where the system Abbreviations . chapter in the book Dynamics of Rolling Stock (in Chinese), by Jianwei Yao Delay and Data Dropout,” IEEE Transactions on Intelligent Trans- . The experiment schemes were jointly developed by Prof.
