Exchange of Modules Among Robot Manipulators Using Part Agents

Abstract

Effective reuse of mechanical parts is one of the important challenges to achieve sustainable society. In this paper, the authors propose a method to exchange modules between manipulators based on part agent system to promote reuse of mechanical parts. The paper describes a plan of experiment with ten manipulators.

The part agent system the authors are developing manages modularized robotic manipulators to investigate the scheme on exchanging modules. The manipulator proposed for the experiment consists of modules that are designed for easy replacement. Each module consists of a link, a joint, a motor, and an angle sensor. The manipulator has three degrees of freedom; contains two modules, i.e., upper and lower arm; and performs simple “pick-and-place” tasks. The system controls and manages information on the module and gathers related sensory data. It monitors its feedback value, while controlling the module, and detects deterioration by checking the deviation of these values. A prototype manipulator with a single degree of freedom is built, and preliminary experiment using this prototype is carried out. The result reveals that deterioration can be detected by monitoring the feedback. When the necessity of exchange of modules is determined based on the acquired deterioration, the system seeks modules in other manipulators that are appropriate to be exchanged. If an appropriate module is found, the target module is exchanged with the selected module.

After a discussion on the remaining issues to implement the part agent system for exchange modules, the paper is concluded.

Appendix: A Trial Design of Module Replaceable Manipulator

Before building the manipulators for the experiment of module replacement, we developed a prototype of modularized manipulator to investigate points of attention in design. The purpose of modularization is to realize easy assembly and disassembly of manipulators in order to facilitate the reuse of their parts as well as to provide units of function. The module is the unit that is replaced and reused and to which a part agent is assigned.

Figure 1.11 shows the modularized manipulator prototype . It has four degrees of freedom with an end effector for grasping objects. It consists of four modules, a hand, two links, and a base. Each module is fixed on the flange of a motor and a shaft that is aligned with the output axis of the motor. This simplifies the connection and disconnection of the module by inserting or pulling it out of its rotational axis shaft. The link modules that were manufactured based on this design are shown in Fig. 1.12. We designed both link modules in the same way and mutually interchangeable to increase their reusability. For this purpose, the flange of the motor for link modules is fixed in the same plane as shown in the figure. This common plane ensures the interchangeability of the two modules. We confirmed that the modules are easily connected and disconnected by inserting and pulling them out of the shafts.

Fig. 1.11

Prototype modularized manipulator

Fig. 1.12

Link modules