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Journal ArticleDOI

Invariant Trajectory Tracking With a Full-Size Autonomous Road Vehicle

01 Aug 2010-IEEE Transactions on Robotics (IEEE)-Vol. 26, Iss: 4, pp 758-765
TL;DR: Two complementary nonlinear Lyapunov-based tracking-control laws are proposed to solve the problem of stabilization of precalculated state trajectories for speeds between ±6 m/s and they provide a smooth, singularity-free stopping transient.
Abstract: Safe handling of dynamic inner-city scenarios with autonomous road vehicles involves the problem of stabilization of precalculated state trajectories. In order to account for the practical requirements of the holistic autonomous system, we propose two complementary nonlinear Lyapunov-based tracking-control laws to solve the problem for speeds between ±6 m/s. Their designs are based on an extended kinematic one-track model, and they provide a smooth, singularity-free stopping transient. With regard to autonomous test applications, the proposed tracking law without orientation control performs much better with respect to control effort and steering-input saturation than the one with orientation control but needs to be prudently combined with the latter for backward driving. The controller performance is illustrated with a full-size test vehicle.
Citations
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Journal ArticleDOI
13 May 2012
TL;DR: An overview of the most current trends in autonomous vehicles is given, highlighting the concepts common to most successful systems as well as their differences, and concludes with an outlook into the promising future of autonomous vehicles.
Abstract: Autonomous vehicles promise numerous improvements to vehicular traffic: an increase in both highway capacity and traffic flow because of faster response times, less fuel consumption and pollution thanks to more foresighted driving, and hopefully fewer accidents thanks to collision avoidance systems. In addition, drivers can save time for more useful activities. In order for these vehicles to safely operate in everyday traffic or in harsh off-road environments, a multitude of problems in perception, navigation, and control have to be solved. This paper gives an overview of the most current trends in autonomous vehicles, highlighting the concepts common to most successful systems as well as their differences. It concludes with an outlook into the promising future of autonomous vehicles.

306 citations


Cites background from "Invariant Trajectory Tracking With ..."

  • ...Data from successive LIDAR point clouds or stereo camera range images is condensed into a regular metric grid....

    [...]

Journal ArticleDOI
TL;DR: This paper deals with the trajectory generation problem faced by an autonomous vehicle in moving traffic and proposes a semi-reactive planning strategy that realizes all required long-term maneuver tasks while providing short-term collision avoidance.
Abstract: This paper deals with the trajectory generation problem faced by an autonomous vehicle in moving traffic. Being given the predicted motion of the traffic flow, the proposed semi-reactive planning strategy realizes all required long-term maneuver tasks (lane-changing, merging, distance-keeping, velocity-keeping, precise stopping, etc.) while providing short-term collision avoidance. The key to comfortable, human-like as well as physically feasible trajectories is the combined optimization of the lateral and longitudinal movements in street-relative coordinates with carefully chosen cost functionals and terminal state sets (manifolds). The performance of the approach is demonstrated in simulated traffic scenarios.

230 citations


Cites background or methods from "Invariant Trajectory Tracking With ..."

  • ...The generated trajectory is in turn stabilized by multiple low-level feedback controllers (see e. g. Werling et al. (2010a))....

    [...]

  • ...On top of the aforementioned features, our method (a first draft has been presented in Werling et al. (2010b)) is characterized by unobtrusive, comfortable maneuvers at a wide speed range....

    [...]

Journal ArticleDOI
TL;DR: An envelope control framework is proposed for four-wheel independently actuated autonomous ground vehicle (AGV) to regulate it on desired path and simultaneously control it to the driving limits and autonomous driving experiments on racetrack validate the efficiency of the proposed controller.
Abstract: This paper proposes an envelope control framework for four-wheel independently actuated autonomous ground vehicle (AGV) to regulate it on desired path and simultaneously control it to the driving limits. The envelope control framework is achieved based on the integrated control of active front-wheel steer and direct yaw-moment control. In a speed controller, the G-G diagram is used to describe the driving limits on each path segment. The desired traction and braking force is calculated according to the G-G diagram and desired path. In a path-following controller, a feedforward–feedback lateral controller is designed to calculate the desired steering angle to follow the desired path. In a yaw-moment controller, the β–r phase portraits are utilized to describe the handling limits. The yaw-moment controller aims at keeping the AGV from losing stability in limit driving, which is calculated through a sliding mode controller and provided by the independent motors actuation. Through an independent driving technique, the tyre cornering stiffness is estimated online based on the predefined Magic Formula model to improve the controller's robustness. An autonomous Formula Student racecar developed by the authors is used as testbed. The autonomous driving experiments on racetrack validate the efficiency of the proposed controller.

130 citations

Posted Content
TL;DR: Results of the research carried out by all finalists within the last five years after the DARPA Urban Challenge are summarized and provides an outlook where further investigation especially for software engineering is now necessary to achieve the goal of driving safely and reliably through urban environments with an anticipatory vehicle for the mass-market.
Abstract: In November 2007 the international competition DARPA Urban Challenge took place on the former George Airforce Base in Victorville, California to significantly promote the research and development on autonomously driving vehicles for urban environments. In the final race only eleven out of initially 89 competitors participated and "Boss" from Carnegie Mellon University succeeded. This paper summarizes results of the research carried out by all finalists within the last five years after the competition and provides an outlook where further investigation especially for software engineering is now necessary to achieve the goal of driving safely and reliably through urban environments with an anticipatory vehicle for the mass-market.

89 citations

Journal ArticleDOI
TL;DR: In this article, a novel dynamics controller for autonomous vehicle to simultaneously control it to the driving limits and follow the desired path is proposed, which consists of longitudinal and lateral controllers, and the stability analysis of the closed-looped error dynamics shows that the controller remains stable against parameters uncertainties in extreme condition such as tyre saturation.

80 citations

References
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Book
01 Jan 1995
TL;DR: In this paper, the focus is on adaptive nonlinear control results introduced with the new recursive design methodology -adaptive backstepping, and basic tools for nonadaptive BackStepping design with state and output feedbacks.
Abstract: From the Publisher: Using a pedagogical style along with detailed proofs and illustrative examples, this book opens a view to the largely unexplored area of nonlinear systems with uncertainties. The focus is on adaptive nonlinear control results introduced with the new recursive design methodology--adaptive backstepping. Describes basic tools for nonadaptive backstepping design with state and output feedbacks.

6,923 citations

Journal ArticleDOI
TL;DR: In this paper, the authors introduce flat systems, which are equivalent to linear ones via a special type of feedback called endogenous feedback, which subsumes the physical properties of a linearizing output and provides another nonlinear extension of Kalman's controllability.
Abstract: We introduce flat systems, which are equivalent to linear ones via a special type of feedback called endogenous. Their physical properties are subsumed by a linearizing output and they might be regarded as providing another nonlinear extension of Kalman's controllability. The distance to flatness is measured by a non-negative integer, the defect. We utilize differential algebra where flatness- and defect are best defined without distinguishing between input, state, output and other variables. Many realistic classes of examples are flat. We treat two popular ones: the crane and the car with n trailers, the motion planning of which is obtained via elementary properties of plane curves. The three non-flat examples, the simple, double and variable length pendulums, are borrowed from non-linear physics. A high frequency control strategy is proposed such that the averaged systems become flat.

3,025 citations

Journal ArticleDOI
TL;DR: Application to the control of nonholonomic wheeled mobile robots is described by considering the case of a car pulling trailers, and globally stabilizing time-varying feedbacks are derived.
Abstract: Chain form systems have recently been introduced to model the kinematics of a class of nonholonomic mechanical systems. The first part of the study is centered on control design and analysis for nonlinear systems which can be converted to the chain form. Solutions to various control problems (open-loop steering, partial or complete state feedback stabilization) are either recalled, generalized, or developed. In particular, globally stabilizing time-varying feedbacks are derived, and a discussion of their convergence properties is provided. Application to the control of nonholonomic wheeled mobile robots is described in the second part of the study by considering the case of a car pulling trailers. >

1,094 citations

Journal ArticleDOI
TL;DR: In this article, the authors considered the swing-up control problem of a two-degree-of-freedom planar robot with a single actuator and gave conditions under which the response of either degree of freedom may be globally decoupled from the response on the other and linearized.
Abstract: Underactuated mechanical systems are those possessing fewer actuators than degrees of freedom. Examples of such systems abound, including flexible joint and flexible link robots, space robots, mobile robots, and robot models that include actuator dynamics and rigid body dynamics together. Complex internal dynamics, nonholonomic behavior, and lack of feedback linearizability are often exhibited by such systems, making the class a rich one from a control standpoint. In this article the author studies a particular underactuated system known as the Acrobot: a two-degree-of-freedom planar robot with a single actuator. The author considers the so-called swing up control problem using the method of partial feedback linearization. The author gives conditions under which the response of either degree of freedom may be globally decoupled from the response of the other and linearized. This result can be used as a starting point to design swing up control algorithms. Analysis of the resulting zero dynamics as well as analysis of the energy of the system provides an understanding of the swing up algorithms. Simulation results are presented showing the swing up motion resulting from partial feedback linearization designs. >

978 citations

Journal ArticleDOI
TL;DR: It is demonstrated how adaptive switching supervisory control can be combined with a nonlinear Lyapunov-based tracking control law to solve the problem of global boundedness and convergence of the position tracking error to a neighborhood of the origin that can be made arbitrarily small.
Abstract: We address the problem of position trajectory-tracking and path-following control design for underactuated autonomous vehicles in the presence of possibly large modeling parametric uncertainty. For a general class of vehicles moving in either 2- or 3-D space, we demonstrate how adaptive switching supervisory control can be combined with a nonlinear Lyapunov-based tracking control law to solve the problem of global boundedness and convergence of the position tracking error to a neighborhood of the origin that can be made arbitrarily small. The desired trajectory does not need to be of a particular type (e.g., trimming trajectories) and can be any sufficiently smooth bounded curve parameterized by time. We also show how these results can be applied to solve the path-following problem, in which the vehicle is required to converge to and follow a path, without a specific temporal specification. We illustrate our design procedures through two vehicle control applications: a hovercraft (moving on a planar surface) and an underwater vehicle (moving in 3-D space). Simulations results are presented and discussed.

848 citations

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