A reusable operational software architecture for advanced robotics

Abstract

Robotic software can be broadly categorized into two levels. The first is the actuator control software. The other level is the system control software. Three layers further comprise the system control software. The top-most is the man-machine interface. The lowest is the real-time control layer. The middle layer is known as the operational software layer. Current industrial robots are monolithic six degrees-of-freedom manipulators that have minimal operational software requirements. On the other hand, advanced robots are based on modularity, redundancy, fault-tolerance, and performance. The operational software layer for these robots should be general and reconfigurable, and should support kinematics, dynamics, deflection modeling, performance criteria, fault-tolerance, and condition-based maintenance. The development of a reusable and general architecture for the operational software layer is the prime goal of this research. This includes: (1) requirements generation for an advanced robotic software system, (2) the selection of a development, execution, and test environment, (3) the development of a reusable software architecture to support Operational Software Components for Advanced Robots (OSCAR), (4) the development of applications to demonstrate OSCAR in simulation on a wide variety of robots and in real-time on a seventeen degrees-of-freedom dual-arm manipulator, (5) the design and development of experiments to validate the advantages of OSCAR, (6) development and demonstration of a real-time formulation of the direct-search generalized inverse kinematics scheme. The development of OSCAR is based on object-oriented design. Object-oriented design professes the development of software components that are extensible and have standardized interfaces. The application of this philosophy led to the break-down of the advanced robotics domain into sub-domains. An analysis of these sub-domains lead to the identification of components that made up the sub-domain. A detailed analysis and design of these components then followed. Applications and experimentation validated the effectiveness of this software architecture. Achieved goals of this software architecture were demonstrated by the applications. The experiments demonstrated that OSCAR provided a 30% improvement in its 'ease of use' and an approximately 200% reduction in program development time as compared to the other robotic software in use at the Robotics Research Group. The real-time formulation of the direct-search inverse kinematics technique showed a 170-times performance improvement when used on a seven degrees-of-freedom robot.