Adel Abbaspour, S. Ali A. Moosavian, and Khalil Alipour
Multiple robots, formation control, obstacle avoidance, nonholonomic mobile robot, virtual structure, mutual feedback
Redundancy is frequently used in the systems that require high fault tolerance and high precision. Using a team of multiple robots would enhance system robustness with respect to a single point failure in the sense that we can reconfigure the team and reassign a new task to each agent. This paper studies formation control and obstacle avoidance for a group of wheeled mobile robots under severe disturbances and system uncertainties. To this end, based on explicit dynamics modelling of nonholonomic mobile robots, the concept of potential field is used, and then a new developed approach to provide formation control for a group of robots to keep a desired formation under significant disturbances is proposed. First, dynamics model of the constrained nonholonomic system has been derived using Lagrange formulation. Next, the potential field theory is exploited to provide a resolution strategy among possibly conflicting performance goals. Then, a virtual structure (VS) control strategy with mutual feedback between robots and formation feedback with virtual centre is proposed to achieve formation control. The advantage of this control scheme is to maintain the desired formation and simultaneously provide a robust tracking control under severe disturbances and system uncertainties through the use of mutual and formation feedback. The obtained results reveal the feasibility and effectiveness of the proposed formation control method in the presence of significant disturbances, uncertainties and various obstacles.
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