Hardware & Software Solution for Rapid Reconfiguration of Heterogeneous Robots

Abstract

In cases of emergency situations, accidents, disasters, in process of reclamation of Arctic and Antarctic, exploration other planets the maximum uncertainty in terms of anticipated working conditions makes it very hard or even impossible to plan and to choose the needed robotics. To perform tasks in such conditions, one should use robots with variable structure, i.e. modular mobile robots, which should have hardware and software capable of rapid reconfiguration. We propose a hardware and software solution for information-measuring and control system (IMCS) of a heterogeneous modular robot, which is sufficiently simple to implement and which is able to reconfigure automatically. It is necessary to require that each module's construction must correspond to its functional purpose and its own IMCS must provide informational and executional functionality. We implement distributed control in such structure, similar to multi-agent systems, via decoupling computational and control process of robot goal function execution into functional subprocesses and distributing them between microcomputers of modules. System-wide robot control is running on a separate module, which plays role of a supervisor for other modules. Executive module is fully responsible for functional subprocess realization. We propose usage of a broadband, reliable and low-cost interface on top of Ethernet standard to organize intermodular interaction. The choice of Ethernet standard enables local-area like design of robot IMCS with IMCS of modules as its nodes. One should use microcontrollers or, as maximum, singleboard computers, i.e. embedded systems as computational devices for IMCS of modules. Informational intermodular interaction is developed using ZeroMQ library with addition of UDP protocol with broadcast messages. This solution led to development of the specification for embedded systems (in contrast to Robotic Operating System), i.e. a unified system of driver development rules. Drivers are a set of control instructions and network protocols to create module's application programming interface (API). Proposed hardware and software solution was tested successfully using laboratory model of heterogeneous modular mobile robot, consisting of module-supervisor, wheeled transport module, close-range sensors module and power module (batteries). A new method of movement planning using two-dimension vector fields is proposed for transport module which is implemented as a full-functional mechatronics device.