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Zhu Y.,Tsinghua University | Zhu Y.,National Key Laboratory of Flight Vehicle Control Integrated Technology | Zhang T.,Tsinghua University | Zhang T.,National Key Laboratory of Flight Vehicle Control Integrated Technology | And 2 more authors.
Kongzhi Lilun Yu Yingyong/Control Theory and Applications | Year: 2010

The path planning method based on the artificial potential field (APF) has attracted many researchers for more than twenty years. However, most of them focused their attention to theoretical aspects and considered the robot a particle or rigid body without constraints. Therefore many achievements can not be applied directly to wheeled mobile robots with nonholonomic constraints. To apply the APF method on a wheeled mobile robot, we theoretically analyze two existing approaches and reveal their hidden failures in reaching the target and the unbalanced performances of path planning in different environments. A new method based on fuzzy rules has been proposed to solve these problems by modifying the control pattern or parameters in different situations. Simulation studies show that the proposed method can acquire better overall performance in various environments on the premise of reaching the target. Source


Zhu Y.,Tsinghua University | Zhu Y.,Tsinghua National Laboratory for Information Sciences and Technology | Zhu Y.,National Key Laboratory of Flight Vehicle Control Integrated Technology | Zhang T.,Tsinghua University | And 8 more authors.
Knowledge-Based Systems | Year: 2012

Focusing on the navigation problem of mobile robots in environments with incomplete knowledge, a new hybrid navigation algorithm is proposed. The novel system architecture in the proposed algorithm is the main contribution of this paper. Unlike most existing hybrid navigation systems whose deliberative layers usually play the dominant role while the reactive layers are only simple executors, a more independent reactive layer that can guarantee convergence without the assistance of a deliberative layer is pursued in the proposed architecture, which brings two benefits. First, the burden of the deliberative layer is released, which is beneficial to guaranteeing real-time property and decreasing resource requirement. Second, some possible layer conflicts in the traditional architecture can be resolved, which improves the system stability. The convergence of the new algorithm has been proved. The simulation results show that compared with three traditional algorithms based on different architectures, the new hybrid navigation algorithm proposed in this paper performs more reliable in terms of escaping from traps, resolving conflicts between layers and decreasing the computational time for avoiding time out of the control cycle. The experiments on a real robot further verify the validity and applicability of the new algorithm. © 2011 Elsevier B.V. All rights reserved. Source


Zhu Y.,Tsinghua University | Zhu Y.,Tsinghua National Laboratory for Information Sciences and Technology | Zhu Y.,National Key Laboratory of Flight Vehicle Control Integrated Technology | Zhang T.,Tsinghua University | And 8 more authors.
Robotics and Computer-Integrated Manufacturing | Year: 2013

A hybrid navigation strategy is proposed in this paper for solving the navigation problem of multiple mobile robots. The proposed strategy integrates three algorithms that represent three different types of existing methods in a layered system. The bottom-up architecture of this system is the main contribution of this paper. This architecture pursues reliable low-level layers that can independently work in as much cases as possible, and the high-level layer is used only when it is necessary for guaranteeing convergence in complex situations. The simulation results show that the proposed strategy has well combined the algorithms of different types from the perspective of pursuing reactivity in the premise of ensuring convergence. Compared with the traditional top-down hybrid architecture, the bottom-up architecture proposed in this paper is more suitable for multi-robot navigation since it can better utilize the advantages of different algorithms to deal with different situations. The experiments on real robots have further verified the applicability of the proposed strategy. © 2012 Elsevier Ltd. All rights reserved. Source


Zhu Y.,Tsinghua University | Zhu Y.,National Key Laboratory of Flight Vehicle Control Integrated Technology | Zhang T.,Tsinghua University | Zhang T.,National Key Laboratory of Flight Vehicle Control Integrated Technology | And 2 more authors.
Zidonghua Xuebao/Acta Automatica Sinica | Year: 2010

The local minima problem of path planning based on potential field has attracted attention for many years. A behavior based solution is proposed in this paper for mobile robots in unknown environments. Proper switching conditions for each behavior are designed to guarantee the validity of the proposed method. Furthermore, memory is incorporated to enhance the capability of understanding the vicinity of the robot, and therefore the robot can eliminate its blindness of decision and select the proper behavior in the current situation more correctly. The validity of the proposed method for obstacles with convex boundaries has been proved. For some complicated obstacles with concave boundaries, simulation studies indicate that the proposed method is more reliable than some previous methods. Experiments based on a real robot verify the applicability of the proposed method. Copyright © Acta Automatica Sinica. All rights reserved. Source


Zhu Y.,Tsinghua University | Zhu Y.,National Key Laboratory of Flight Vehicle Control Integrated Technology | Zhang T.,Tsinghua University | Zhang T.,National Key Laboratory of Flight Vehicle Control Integrated Technology | And 6 more authors.
Chinese Control Conference, CCC | Year: 2013

Low-level issues related to task execution are often oversimplified or ignored in research works of multi-robot cooperation. In this paper, a multi-robot cooperative system considering both high-level task allocation issues and low-level task execution issues is proposed. Simulation results show that both task allocation and execution algorithms will affect the system performance, which indicates that it is more reasonable to consider them as an integrated problem rather than independent issues. Practical experiments further verify the applicability of the cooperative system proposed in this paper. © 2013 TCCT, CAA. Source

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