Mobile robots with non-holonomic kinematics have three degrees of freedom for planar motion, but only there are two control inputs available. The stabilization problem for such robots is known not to be solvable via s...
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Mobile robots with non-holonomic kinematics have three degrees of freedom for planar motion, but only there are two control inputs available. The stabilization problem for such robots is known not to be solvable via smooth time-invariant feedback. We propose to utilize a Lyapunov function to prescribe a set of desired trajectories to navigate robot to a specified configuration. Ideal tracking of the prescribed trajectories is achieved by exploiting the invariance property and the order reduction property of sliding mode control. The mobile robot is shown to be exponentially stabilizable for a class of quadratic Lyapunov functions.
Features of an available computation environment for robot-dynamics design are described. These are environments for object-oriented mechatronics/robot dynamics modeling, for executing dynamics simulation experiments,...
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ISBN:
(纸本)0818653329
Features of an available computation environment for robot-dynamics design are described. These are environments for object-oriented mechatronics/robot dynamics modeling, for executing dynamics simulation experiments, for multiobjective parameter and trajectory optimization, and for multivariate result visualization. The environments have a common look and feel and are coherently integrated using an engineering database system.
Autonomous navigation in unknown cluttered environments is one of the corner-stones of future applications of mobile robots. The complexity even of seemingly simple problems like point-to-point travel, to be solved in...
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Autonomous navigation in unknown cluttered environments is one of the corner-stones of future applications of mobile robots. The complexity even of seemingly simple problems like point-to-point travel, to be solved in real-time, calls for a hierarchical system architecture. We present a three-layered path control system with three modules 'global planning', 'local navigation', and 'collision avoidance'. Each module is restricted to a subtask of limited competence and responsibility, allowing for on-line implementation within the associated time frame. Suitable module interaction provides the desired behavior of the overall system. This paper summarizes the main idea of each of the three modules. Experimental results with the Siemens mobile platform ROAMER illustrate the methodology and performance of the path control system in unprepared cluttered environments.
The fuzzy-control methodology can be seen as a systematic way to specify controllers with nonlinear gain surfaces. To properly tune such controllers, computer-aided techniques can be applied provided appropriate plant...
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ISBN:
(纸本)0780318005
The fuzzy-control methodology can be seen as a systematic way to specify controllers with nonlinear gain surfaces. To properly tune such controllers, computer-aided techniques can be applied provided appropriate plant models are available such as in more classical design approaches. In particular, it is shown how a multi-models/multi-criteria design for controllers with fuzzy logic can be carried out by using the ANDECS_MOPS Multi-Objective Programming system. For that a Control Data Object 'Fuzzy-Controller' is developed together with a graphical editor for defining the linguistic variables. This represents the dynamic synthesis part of the design framework. Using a model building environment like Dymola or ACSL which is linked to ANDECS via DSblock, the fuzzy controller connected to dynamic plant models can be optimized by MOPS. This is demonstrated for a multicriteria design problem for an aerodynamically unstable aircraft.
Highway automation is a promising approach to cope with increasing road traffic and congestions. An important control subtask of an Intelligent Vehicle/Highway system is automatic steering for lateral vehicle control....
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Highway automation is a promising approach to cope with increasing road traffic and congestions. An important control subtask of an Intelligent Vehicle/Highway system is automatic steering for lateral vehicle control. Due to system uncertainties and the wide range of operating conditions, state-of-the-art robust control techniques are required. This paper introduces two automatic steering controllers for cars driving under highway conditions. The control design is based on sliding mode control and robust state observation. It is shown that good tracking of a reference path, delineated either continuously or discretely, can be achieved with a minimum effort in sensing and without preview of the road curvature.
This paper establishes a general framework for the passing of mobile robots through narrow passages. Under such circumstances, the artificial potential method often leads to oscillatory motion (Koren et al. 1991) or e...
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This paper establishes a general framework for the passing of mobile robots through narrow passages. Under such circumstances, the artificial potential method often leads to oscillatory motion (Koren et al. 1991) or even lock-up situations (Khosla et al. 1988, Noborio et al. 1990). Sliding mode theory is utilized to examine the gradient of an artificial potential in the vicinity of the equi-distance line between the passage constraints. State-dependent and time-dependent smoothing methods are introduced to enable safe passing. The methodology is illustrated in experiments with the Siemens mobile platform ROAMER.
This paper introduces a new integrated path control strategy (combined path planning and motion control) for autonomous systems of arbitrary dimension. A harmonic artificial potential field is used to specify admissib...
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This paper introduces a new integrated path control strategy (combined path planning and motion control) for autonomous systems of arbitrary dimension. A harmonic artificial potential field is used to specify admissible trajectories leading around obstacles. Using a sliding mode controller, motion is generated along the gradient lines of the potential field, avoiding collisions with the obstacles. The extremely low computational complexity of the proposed method makes it very suitable for on-line applications. The strategy is applied to mobile robots moving amidst known obstacles. Only the obstacle closest to the robot is considered at each time instance. The switching of the two respective gradient fields along the equi-distance line between two obstacles leads to the interesting phenomenon of an additional `spatial' sliding surface, which is examined in detail. The algorithm guarantees approaching the goal point continuously, following a reasonably short path. Numerical examples are presented to demonstrate the utility of this new strategy.
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