Behaviour-based cooperation between two mobile manipulators¹

Article type: Research Article

Authors: Sequeira, João | Ribeiro, M. Isabel^{; *}

Affiliations: Instituto Superior Técnico, Instituto de Sistemas e Robótica, IST -- Torre Norte, Av. Rovisco Pais 1, 1049-001 Lisboa, Portugal. E-mail: [email protected], [email protected]

Correspondence: [*] Corresponding author.

Note: [1] Work sponsored by the programme PRAXIS XXI, project COOPERA - 2/2.1/TPAR/2087/95.

Abstract: This paper describes a framework to model a behaviour-based approach to cooperation between two mobile manipulators transporting a rigid bar. The two mobile manipulators cooperate with each other in the sense that they are able to execute an assigned mission, managing to hold the bar and avoiding any physical contact between them. In each mission, an ordered sequence of workspace points must be reached by the bar. One grasping point is fixed at the predefined extremity of the bar whereas the other is allowed to slide along the bar and both manipulators are assumed to grasp the bar using a compliant connection. The additional degree of freedom introduced by the sliding of one of the grasping points increases the solutions space of the problem and, simultaneously, constrains the direction of search for these solutions. The control methodology proposed in this paper for each single robot is supported in the definition of equivalence classes in a state space of aggregates of feasible trajectories. Within a natural language context, these aggregates are identifiable with robot's behaviours. It is shown that two basis operations induce a non proper semiring structure in a subspace of the state space. Experimental results, using real and simulated mobile manipulators, illustrate the overall performance.

DOI: 10.3233/ICA-2000-7302

Journal: Integrated Computer-Aided Engineering, vol. 7, no. 3, pp. 193-215, 2000