2 | Agent architectures and hierarchical control Flashcards
What is an agent?
An agent is something that acts in an environment.
What is an embodied agent?
An embodied agent has a physical body.
What is an actuator?
Agents act in the world through their actuators, also called effectors. Actuators can also be noisy, unreliable, slow, or broken. What an agent controls is the message (command) it sends to its actuators.
What is an agent system?
An agent system is made up of an agent and the environment in which it acts. The agent receives stimuli from the environment and carries out actions in the environment.
What is the agent function?
Agents are situated in time; they receive sensory data in time and do actions in time. The action that an agent does at a particular time is a function of its inputs.
What is hierarchical control?
An alternative architecture is a hierarchy of controllers. Each layer sees the layers below it as a virtual body from which it gets percepts and to which it sends commands. The planning horizon at the lower level is much shorter than the planning horizon at upper levels. The lower-level layers run much faster, react to those aspects of the world that need to be reacted to quickly, and deliver a simpler view of the world to the higher layers, hiding details that are not essential for the higher layers. People have to react to the world, at the lowest level, in fractions of a second, but plan at the highest-level even for decades into the future. For example, the reason for doing some particular university course may be for the long-term career.
What is dead reckoning?
At one extreme, a model may be so good that the agent can ignore its percepts. The agent can then determine what to do just by reasoning. This approach requires a model of both the state of the world and the dynamics of the world. Given the state at one time, and the dynamics, the state at the next time can be predicted.
What is a pure reactive system?
At the other extreme is a purely reactive system that bases its actions on the percepts, but does not update its internal belief state. The command function in this case is a function from percepts into actions.
What is an ontology?
In AI, an ontology is a specification of the meaning of the symbols used in an information system, where symbols refer to things that exist. An ontology specifies what exists and the vocabulary used to describe what exists.
Which two main components does the agent contain?
An agent is made up of a body and a controller. The
controller receives percepts from the body and sends commands to the body.
A body includes sensors that convert stimuli into percepts
and actuators that convert commands into actions.
What are an agents belief state and its current percepts?
A controller maintains the agent’s belief state and determine what command to issue at each time. The information it has available when it must do this are its belief state and its current percepts.
What does it mean that a control problem is separable?
A control problem is separable if the best action can be obtained by first finding the best model of the world and then using that model to determine the best action
