It also plans for, and issues tasks to, the subordinate nodes. Behavior generation is responsible for executing tasks received from the superior, parent node.Albus defines each node to contain these components. James Albus, while at NIST, developed a theory for intelligent system design named the Reference Model Architecture (RMA), which is a hierarchical control system inspired by RCS. Ĭonstituents in a node from James Albus's Reference Model Architecture Reinforcement learning has been used to acquire behavior in a hierarchical control system in which each node can learn to improve its behavior with experience. Behavior need not be planned by a superior layer, rather behaviors may be triggered by sensory inputs and so are only active under circumstances where they might be appropriate. the decision to move forward by the eat-food layer takes into account the decision of the lowest obstacle-avoidance layer. Each layer's goal subsumes that of the underlying layers, e.g. system as a whole), and higher layers are increasingly more abstract.
#Hierarchical control system software
Each layer implements a particular goal of the software agent (i.e. This architecture is a way of decomposing complicated intelligent behavior into many "simple" behavior modules, which are in turn organized into layers. Subsumption architecture is a methodology for developing artificial intelligence that is heavily associated with behavior based robotics. The winning entry, Tartan Racing employed a hierarchical control system, with layered mission planning, motion planning, behavior generation, perception, world modelling, and mechatronics. In November 2007, DARPA held the Urban Challenge. NIST built on earlier research to develop its Real-Time Control System (RCS) and Real-time Control System Software which is a generic hierarchical control system that has been used to operate a manufacturing cell, a robot crane, and an automated vehicle. networked) intelligent control systems for applications such as military command and control systems. In the early 1990s DARPA sponsored research to develop distributed (i.e. Its Automated Manufacturing Research Facility was used to develop a five layer production control model. Computer-aided production engineering has been a research focus at NIST since the 1980s. In perceptual control theory, which postulates that an organism's behavior is a means of controlling its perceptions, the organism's control systems are suggested to be organized in a hierarchical pattern as their perceptions are constructed so.Īpplications Edit Manufacturing, robotics and vehicles EditĪmong the robotic paradigms is the hierarchical paradigm in which a robot operates in a top-down fashion, heavy on planning, especially motion planning. A hierarchical task network is a good fit for planning in a hierarchical control system.īesides artificial systems, an animal's control systems are proposed to be organized as a hierarchy. The higher layers, having relaxed time constraints, are capable of reasoning from an abstract world model and performing planning. The layers form a hybrid intelligent system in which the lowest, reactive layers are sub-symbolic. The lower layers have local tasks, goals, and sensations, and their activities are planned and coordinated by higher layers which do not generally override their decisions.Each higher layer of the tree operates with a longer interval of planning and execution time than its immediately lower layer.The two distinguishing features of a hierarchical control system are related to its layers. Nodes may also exchange messages with their siblings. Commands, tasks and goals to be achieved flow down the tree from superior nodes to subordinate nodes, whereas sensations and command results flow up the tree from subordinate to superior nodes. Hierarchical control systems are organized similarly to divide the decision making responsibility.Įach element of the hierarchy is a linked node in the tree. For example, a command hierarchy has among its notable features the organizational chart of superiors, subordinates, and lines of organizational communication. A human-built system with complex behavior is often organized as a hierarchy.