Feedback control framework for car-like robots using the unicycle controllers

Michałek, Maciej Marcin; Kozłowski, Krzysztof

doi:10.1017/s0263574711000750

Cited by 29 publications

(47 citation statements)

References 35 publications

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“…Since (35) will be satisfied. Constraints (35) can be transformed to the following matrices and vectors utilized in (34)…”

Section: Algorithm 1 Vfo-driven Motion Planning Proceduresmentioning

confidence: 98%

“…For example, one could design the motion cost utilized in optimization with consideration of how far away from obstacles should the robot be kept or how fast is curvature of robot motion changing over time. Furthermore, application of the presented approach to more complex robot kinematics such as car-like and N-trailer robots using results from [35] and [33], respectively, is possible. …”

Section: Final Remarksmentioning

confidence: 99%

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The VFO-Driven Motion Planning and Feedback Control in Polygonal Worlds for a Unicycle with Bounded Curvature of Motion

Gawron

Michałek

2017

J Intell Robot Syst

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Integrated motion planning and control for the purposes of maneuvering mobile robots under state-and input constraints is a problem of vital practical importance in applications of mobile robots such as autonomous transportation. Those constraints arise naturally in practice due to specifics of robot mechanical construction and the presence of obstacles in motion environment. In contrast to approaches focusing on feedback control design under the assumption of given reference motion or motion planning with neglection of subsequent feedback motion execution, we adopt a controller-driven motion planning paradigm, which has recently gained attention of many researchers. It postulates design of motion planning algorithms dedicated to specific feedback control policies, which compute a sequence of feedback control subtasks instead of classically planned open-loop controls or parametric paths. In this spirit, we propose a motion planning algorithm driven by the VFO (Vector Field Orientation) control law for the waypointfollowing task. Presented analysis of the VFO control law reveals its beneficial properties, which are subsequently utilized to solve a generally nonlinear and non-convex optimal motion planning problem by formulating it as a mixed-integer linear program (MILP). The solution proposed in this paper yields a waypoint sequence, which is designed for execution by application of the VFO control law to drive a robot to a prescribed final configuration under an input constraint imposed by bounded curvature of robot motion and state constraints resulting from a convex decomposition of task space. Satisfaction of these constraints is guaranteed analytically and exactly, i.e., without utilization of numerical approximations. Moreover, for a given discrete set of possible waypoint orientations, the proposed algorithm computes plans optimal w.r.t. given cost functional, which can be any convex linear combination of quantities such as robot path length, curvature of robot motion, distance to imposed state constraints, etc. Furthermore, the planning algorithm exploits the possibility of both forward or backward movement of the robot to allow maneuvering in demanding environments. Generated waypoint sequences are a compact representation of a motion plan, which can be immediately executed with the VFO controller without any additional postprocessing. Validity of the proposed approach has 266 J Intell Robot Syst (2018) 89:265-297 been confirmed by simulation studies and experimental motion execution with a laboratory-scale mobile robot.

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“…Since (35) will be satisfied. Constraints (35) can be transformed to the following matrices and vectors utilized in (34)…”

Section: Algorithm 1 Vfo-driven Motion Planning Proceduresmentioning

confidence: 98%

Section: Final Remarksmentioning

confidence: 99%

The VFO-Driven Motion Planning and Feedback Control in Polygonal Worlds for a Unicycle with Bounded Curvature of Motion

Gawron

Michałek

2017

J Intell Robot Syst

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“…Previous experience with the VFO controllers devised for the trajectory tracking and set-point control tasks, see [9,22], may suggest selection of k p and k a according to a simple design rule: k a > k p , and in particular k a = 2k p . Selection of k p shall result from a compromise between a desirable rigidity of the controller on one hand, and dominant practical limitations on the other hand, caused usually by the presence of a measurement noise in a feedback loop or by the time delays affecting a control loop.…”

Section: Definition Of the Convergence Vector Fieldmentioning

confidence: 99%

“…Satisfaction of constraint (4) can be guaranteed by application of the so-called Velocity Scaling Block (VSB) utilized, e.g., in [9,22]. The working principles of the VSB can be explained as follows.…”

Section: Control Input Scalingmentioning

confidence: 99%

“…Essential geometry of planar motion for any single-body nonholonomic vehicle can be generically described by a unicycle kinematic model. As a consequence, applicability of control laws devised for the unicycle model can be relatively easily extended to more complex kinematics by employing the cascadelike control approach -see, e.g., [20,22,23].…”

Section: Introductionmentioning

confidence: 99%

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VFO Path following Control with Guarantees of Positionally Constrained Transients for Unicycle-Like Robots with Constrained Control Input

Michałek

Gawron

2017

J Intell Robot Syst

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TheVector-Field-Orientation (VFO) method is a control design concept which was originally introduced for the unicycle kinematics to solve two classical control tasks corresponding to the trajectory tracking and set-point control problems. A unified solution to both the tasks was possible by appropriate definitions of the so-called convergence vector field. So far, there has not been a version of the VFO control law for the third classical control task concerning the path following problem, which is particularly meaningful in the context of practical applications. The paper fills this gap by presenting a novel VFO path following controller devised for robots of unicycle-like kinematics with the amplitudelimited control input. Opposite to most path following controllers proposed in the literature, the new control law utilizes the recently introduced level curve approach which does not employ any parametrization of a reference path. In this way, the proposed solution

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Trajectory Tracking Controller Design for Unmanned Vehicles: A New Methodology

Cheein

Scaglia

2013

Journal of Field Robotics

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A major issue in the automatic guidance of vehicles is the design of control laws dedicated to the specific mobile platform used. Thus, if the model associated with the mobile platform or its constraints change, a new control law must be designed. In this paper, the problem of designing trajectory tracking controllers for unmanned vehicles is addressed. The methodology proposed here is an algebraic approach for obtaining optimum and stable trajectory tracking controllers for nonholonomic vehicles. Such an algebraic formulation makes the proposal suitable for embedded applications. The stability and optimality of the proposed controllers design method is theoretically proven for both bicycle‐type and unicycle‐type mobile robots, although the methodology can be extended to other types of unmanned vehicles. Four tests were carried out in this work in order to show the advantages of the proposal: the step discontinuity test, the curvature test, the real world test, and navigation under disturbances in the control actions. The results obtained were compared with four trajectory tracking controllers previously published in the literature. Additionally, an agricultural application is included in order to show the performance of the proposed controller when applied to a service unit within an agricultural environment. Field experiments demonstrating the capabilities of our proposal are also reported and discussed.

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Feedback control framework for car-like robots using the unicycle controllers

Cited by 29 publications

References 35 publications

The VFO-Driven Motion Planning and Feedback Control in Polygonal Worlds for a Unicycle with Bounded Curvature of Motion

The VFO-Driven Motion Planning and Feedback Control in Polygonal Worlds for a Unicycle with Bounded Curvature of Motion

VFO Path following Control with Guarantees of Positionally Constrained Transients for Unicycle-Like Robots with Constrained Control Input

Trajectory Tracking Controller Design for Unmanned Vehicles: A New Methodology

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