2,316 research outputs found
Real time implementation of socially acceptable collision avoidance of a low speed autonomous shuttle using the elastic band method
This paper presents the real time implementation of socially acceptable collision avoidance using the elastic band method for low speed autonomous shuttles operating in high pedestrian density environments. The modeling and validation of the research autonomous vehicle used in the experimental implementation is presented first, followed by the details of the Hardware-In-the-Loop connected and autonomous vehicle simulator used. The socially acceptable collision avoidance algorithm is formulated using the elastic band method as an online, local path modification algorithm. Parameter space based robust feedback plus feedforward steering controller design is used. Model-in-the-loop, Hardware-In-the-Loop and road testing in a proving ground are used to demonstrate the effectiveness of the real time implementation of the elastic band based socially acceptable collision avoidance method of this paper
Hardware in the Loop Simulation of Active Front Wheel Steering control for yaw disturbance rejection
This paper introduces an Active Front Wheel Steering (AFWS)
control for the purpose of reducing unwanted yaw motion. Side wind forces are considered to be the sources of yaw disturbance in this study. The proposed control strategy for the AFWS is a lateral directional control with yaw rate feedback. The AFWS controller was implemented on Hardware in the Loop Simulation (HiLS) using an AFWS test rig. From the simulation and experimental results, AFWS control is able to perform the task of yaw disturbance attenuation by providing additional steering correction for maintaining the original direction of the vehicle.
Keywords: active front wheel steering; side wind force; yaw cancellation;
HiLS; vehicle safety
The Limited Integrator Model Regulator And its Use in Vehicle Steering Control
Unexpected yaw disturbances like braking on unilaterally icy road, side wind
forces and tire rupture are very difficult to handle by the driver of a road
vehicle, due to his/her large panic reaction period ranging between 0.5 to 2
seconds. Automatic driver assist systems provide counteracting yaw moments
during this driver panic reaction period to maintain the stability of the yaw
dynamics of the vehicle. An active steering based driver assist system that
uses the model regulator control architecture is introduced and used here for
yaw dynamics stabilization in such situations. The model regulator which is a
special form of a two degree of freedom control architecture is introduced and
explained in detail in a tutorial fashion whereby its integral action
capability, among others, is also shown. An auxiliary steering actuation system
is assumed and a limited integrator version of the model regulator based
steering controller is developed in order not to saturate the auxiliary
steering actuator. This low frequency limited integrator implementation also
allows the driver to take care of low frequency steering and disturbance
rejection tasks. Linear simulation results are used to demonstrate the
effectiveness of the proposed method
Hardware-in-the-Loop and Road Testing of RLVW and GLOSA Connected Vehicle Applications
This paper presents an evaluation of two different Vehicle to Infrastructure
(V2I) applications, namely Red Light Violation Warning (RLVW) and Green Light
Optimized Speed Advisory (GLOSA). The evaluation method is to first develop and
use Hardware-in-the-Loop (HIL) simulator testing, followed by extension of the
HIL testing to road testing using an experimental connected vehicle. The HIL
simulator used in the testing is a state-of-the-art simulator that consists of
the same hardware like the road side unit and traffic cabinet as is used in
real intersections and allows testing of numerous different traffic and
intersection geometry and timing scenarios realistically. First, the RLVW V2I
algorithm is tested in the HIL simulator and then implemented in an
On-Board-Unit (OBU) in our experimental vehicle and tested at real world
intersections. This same approach of HIL testing followed by testing in real
intersections using our experimental vehicle is later extended to the GLOSA
application. The GLOSA application that is tested in this paper has both an
optimal speed advisory for passing at the green light and also includes a red
light violation warning system. The paper presents the HIL and experimental
vehicle evaluation systems, information about RLVW and GLOSA and HIL simulation
and road testing results and their interpretations
A Real-time Nonlinear Model Predictive Controller for Yaw Motion Optimization of Distributed Drive Electric Vehicles
This paper proposes a real-time nonlinear model
predictive control (NMPC) strategy for direct yaw moment control
(DYC) of distributed drive electric vehicles (DDEVs). The NMPC
strategy is based on a control-oriented model built by integrating
a single track vehicle model with the Magic Formula (MF) tire
model. To mitigate the NMPC computational cost, the
continuation/generalized minimal residual (C/GMRES) algorithm
is employed and modified for real-time optimization. Since the
traditional C/GMRES algorithm cannot directly solve the
inequality constraint problem, the external penalty method is
introduced to transform inequality constraints into an
equivalently unconstrained optimization problem. Based on the
Pontryagin’s minimum principle (PMP), the existence and
uniqueness for solution of the proposed C/GMRES algorithm are
proven. Additionally, to achieve fast initialization in C/GMRES
algorithm, the varying predictive duration is adopted so that the
analytic expressions of optimally initial solutions in C/GMRES
algorithm can be derived and gained. A Karush-Kuhn-Tucker
(KKT) condition based control allocation method distributes the
desired traction and yaw moment among four independent
motors. Numerical simulations are carried out by combining
CarSim and Matlab/Simulink to evaluate the effectiveness of the
proposed strategy. Results demonstrate that the real-time NMPC
strategy can achieve superior vehicle stability performance,
guarantee the given safety constraints, and significantly reduce the
computational efforts
A new model-free design for vehicle control and its validation through an advanced simulation platform
A new model-free setting and the corresponding "intelligent" P and PD
controllers are employed for the longitudinal and lateral motions of a vehicle.
This new approach has been developed and used in order to ensure simultaneously
a best profile tracking for the longitudinal and lateral behaviors. The
longitudinal speed and the derivative of the lateral deviation, on one hand,
the driving/braking torque and the steering angle, on the other hand, are
respectively the output and the input variables. Let us emphasize that a "good"
mathematical modeling, which is quite difficult, if not impossible to obtain,
is not needed for such a design. An important part of this publication is
focused on the presentation of simulation results with actual and virtual data.
The actual data, used in Matlab as reference trajectories, have been obtained
from a properly instrumented car (Peugeot 406). Other virtual sets of data have
been generated through the interconnected platform SiVIC/RTMaps. It is a
dedicated virtual simulation platform for prototyping and validation of
advanced driving assistance systems. Keywords- Longitudinal and lateral vehicle
control, model-free control, intelligent P controller (i-P controller),
algebraic estimation, ADAS (Advanced Driving Assistance Systems).Comment: in 14th European Control Conference, Jul 2015, Linz, Austria. 201
Discrete-time Robust PD Controlled System with DOB/CDOB Compensation for High Speed Autonomous Vehicle Path Following
Autonomous vehicle path following performance is one of significant
consideration. This paper presents discrete time design of robust PD controlled
system with disturbance observer (DOB) and communication disturbance observer
(CDOB) compensation to enhance autonomous vehicle path following performance.
Although always implemented on digital devices, DOB and CDOB structure are
usually designed in continuous time in the literature and also in our previous
work. However, it requires high sampling rate for continuous-time design block
diagram to automatically convert to corresponding discrete-time controller
using rapid controller prototyping systems. In this paper, direct discrete time
design is carried out. Digital PD feedback controller is designed based on the
nominal plant using the proposed parameter space approach. Zero order hold
method is applied to discretize the nominal plant, DOB and CDOB structure in
continuous domain. Discrete time DOB is embedded into the steering to path
following error loop for model regulation in the presence of uncertainty in
vehicle parameters such as vehicle mass, vehicle speed and road-tire friction
coefficient and rejecting external disturbance like crosswind force. On the
other hand, time delay from CAN bus based sensor and actuator command
interfaces results in degradation of system performance since large negative
phase angles are added to the plant frequency response. Discrete time CDOB
compensated control system can be used for time delay compensation where the
accurate knowledge of delay time value is not necessary. A validated model of
our lab Ford Fusion hybrid automated driving research vehicle is used for the
simulation analysis while the vehicle is driving at high speed. Simulation
results successfully demonstrate the improvement of autonomous vehicle path
following performance with the proposed discrete time DOB and CDOB structure
Dynamic Speed Harmonization
In the last decade, the accelerated advancements in manufacturing techniques
and material science enabled the automotive industry to manufacture commercial
vehicles at more affordable rates. This, however, brought about roadways having
to accommodate an ever-increasing number of vehicles every day. However, some
roadways, during specific hours of the day, had already been on the brink of
reaching their capacity to withstand the number of vehicles travelling on them.
Hence, overcrowded roadways create slow traffic, and sometimes, bottlenecks. In
this paper, a Dynamic Speed Harmonization (DSH) algorithm that regulates the
speed of a vehicle to prevent it from being affected by bottlenecks has been
presented. First, co-simulations were run between MATLAB Simulink and CarSim to
test different deceleration profiles. Then, Hardware-in-the-Loop (HIL)
simulations were run with a Road Side Unit (RSU), which emulated a roadside
detector that spotted bottlenecks and sent information to the Connected Vehicle
about the position of the queue and the average speed of the vehicles at the
queue. The DSH algorithm was also tested on a track to compare the performance
of the different deceleration profiles in terms of ride comfort.Comment: 7 pages, 5 figure
- …