• International Journal of Control, Automation, and Systems
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• v.6 no.2
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• pp.282-287
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• 2008

In distributed mobile robot systems, autonomous robots accomplish complicated tasks through intelligent cooperation with each other. This paper presents behavior learning and online distributed evolution for cooperative behavior of a group of autonomous robots. Learning and evolution capabilities are essential for a group of autonomous robots to adapt to unstructured environments. Behavior learning finds an optimal state-action mapping of a robot for a given operating condition. In behavior learning, a Q-learning algorithm is modified to handle delayed rewards in the distributed robot systems. A group of robots implements cooperative behaviors through communication with other robots. Individual robots improve the state-action mapping through online evolution with the crossover operator based on the Q-values and their update frequencies. A cooperative material search problem demonstrated the effectiveness of the proposed behavior learning and online distributed evolution method for implementing cooperative behavior of a group of autonomous mobile robots.

• Journal of applied mathematics & informatics
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• v.41 no.2
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• pp.229-245
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• 2023

In this paper, we consider cooperative elliptic systems under conjugation conditions. We first prove the existence of the state for 2 × 2 cooperative elliptic systems with Dirichlet and Neumann conditions, then we find the set of equations and inequalities that characterizes the optimal control of distributed type for these systems. The case of n × n cooperative systems is also established.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.3
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• pp.460-469
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• 2012

The WiMedia Alliance has specified a Distributed Medium Access Control (D-MAC) protocol based on UWB for high speed wireless home networks and WPANs. In this paper, we propose a novel cooperative communication protocol adaptive to current UWB link transmission rate. The proposed cooperative communication protocol has compatibility with current WiMedia D-MAC and Wireless USB standard and is executed at each device according to a Relay Node Selection (RNS) criterion.

• Journal of Korea Multimedia Society
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• v.15 no.3
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• pp.345-355
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• 2012

The WiMedia Alliance has specified a Distributed Medium Access Control (D-MAC)/WUSB protocol based on UWB for high speed wireless home networks and WPANs. In this paper, we propose a novel SoQ-based cooperative communication protocol adaptive to current UWB link transmission rate and QoS measure. The proposed SoQ-based cooperative communication protocol has compatibility with current WiMedia D-MAC/Wireless USB standard and is executed at each device according to a SoQ-based Relay Node Selection (RNS) criterion.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.3
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• pp.999-1021
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• 2023

Differential spatial modulation uses the antenna index to transmit information, which improves the spectral efficiency, and completely bypasses any channel side information in the recommended setting. A generalized distributed multiple turbo coded-cooperative differential spatial modulation based on distributed multiple turbo code is put forward and its performances in Rayleigh fading channels is analyzed. The generalized distributed multiple turbo coded-cooperative differential spatial modulation scheme is a coded-cooperation communication scheme, in which we proposed a new joint parallel iterative decoding method. Moreover, the code matched interleaver is considered to be the best choice for the generalized multiple turbo coded-cooperative differential spatial modulation schemes, which is the key factor of turbo code. Monte Carlo simulated results show that the proposed cooperative differential spatial modulation scheme is better than the corresponding non-cooperative scheme over Rayleigh fading channels in multiple input and output communication system under the same conditions. In addition, the simulation results show that the code matched interleaver scheme gets a better diversity gain as compared to the random interleaver.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.10
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• pp.3810-3830
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• 2015

In this paper, we investigate the differential game theoretic approach for distributed dynamic cooperative power control in cognitive radio ad hoc networks (CRANETs). First, a payoff function is defined by taking into consideration the tradeoff between the stock of accumulated power interference to the primary networks and the dynamic regulation of the transmit power of secondary users (SUs). Specifically, the payoff function not only reflects the tradeoff between the requirement for quickly finding the stable available spectrum opportunities and the need for better channel conditions, but also reveals the impact of the differentiated types of data traffic on the demand of transmission quality. Then the dynamic power control problem is modeled as a differential game model. Moreover, we convert the differential game model into a dynamic programming problem to obtain a set of optimal strategies of SUs under the condition of the grand coalition. A distributed dynamic cooperative power control algorithm is developed to dynamically adjust the transmit power of SUs under grand coalition. Finally, numerical results are presented to demonstrate the effectiveness of the proposed algorithm for efficient power control in CRANETs.

• Journal of Korea Multimedia Society
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• v.20 no.12
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• pp.1849-1855
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• 2017

The main purpose of cooperative communications is improvement of communication quality and efficient use of transmission power. In this paper, a cooperative retransmission method is proposed, where neighbor nodes that receive messages correctly between transmit and receive nodes will participate in retransmission of the erroneous packet of the direct link. When the proposed retransmission method is used, the performance of the PER can be greatly improved. In case that the limited information is included in the NACK message, the transmit power of the retransmission packet can be reduced using the proper power control method.

• Journal of the Korean Institute of Intelligent Systems
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• v.11 no.7
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• pp.591-597
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• 2001

In this paper, we propose a method of cooperative control (T-cell modeling) and selection of group behavior strategy (B-cell modeling) based on immune system in distributed autonomous robotic system (DARS). Immune system is living body's self-protection and self-maintenance system. These features can be applied to decision making of optimal swarm behavior in dynamically changing environment. For applying immune system to DARS, a robot is regarded as a B-cell, each environmental condition as an antigen, a behavior strategy as an antibody and control parameter as a T-cell respectively. The executing process of proposed method is as follows. When the environmental condition changes, a robot selects an appropriate behavior strategy. And its behavior strategy is stimulated and suppressed by other robot using communication. Finally much stimulated strategy is adopted as a swarm behavior strategy. This control school is based on clonal selection and idiotopic network hypothesis. And it is used for decision making of optimal swarm strategy. By T-cell modeling, adaptation ability of robot is enhanced in dynamic environments.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.1177-1180
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• 1996

In this paper, we propose an algorithm that realizes cooperative behavior by construction of autonomous mobile robot system. Each robot is able to sense other robots and obstacles, and it has the rule of behavior to achieve the goal of the system. In this paper, to improve performance of the whole system, we use Genetic Programming based on Natural Selection. Genetic Programming's chromosome is a program of tree structure and it's major operators are crossover and mutation. We verify the effectiveness of the proposed scheme from the several examples.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.9
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• pp.891-897
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• 2010

This paper proposes a cooperative control algorithm for a dual-arms robot which is carrying an object to the desired location. When the dual-arms robot is carrying an object from the start to the goal point, the optimal path in terms of safety, energy, and time needs to be selected among the numerous possible paths. In order to quantify the carrying efficiency of dual-arms, DAMM (Dual Arm Manipulability Measure) has been defined and applied for the decision of the optimal path. The DAMM is defined as the intersection of the manipulability ellipsoids of the dual-arms, while the manipulability measure indicates a relationship between the joint velocity and the Cartesian velocity for each arm. The cost function for achieving the optimal path is defined as the summation of the distance to the goal and inverse of this DAMM, which aims to generate the efficient motion to the goal. It is confirmed that the optimal path planning keeps higher manipulability through the short distance path by using computer simulation. To show the effectiveness of this cooperative control algorithm experimentally, a 5-DOF dual-arm robot with distributed controllers for synchronization control has been developed and used for the experiments.