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In [[robotics]], a '''robotic paradigm''' is a mental model of how a robot operates.  A robotic paradigm can be described by the relationship between the three basic elements of [[robotics]]: [[Sense Plan Act|Sensing, Planning, and Acting]]. It can also be described by how sensory data is processed and distributed through the system, and where decisions are made.

==Hierarchical/deliberative paradigm==
The hierarchical or deliberative paradigm describes a '''top-down''' control structure in which the robot's actions are driven by explicit planning. The robot follows a sense-plan-act sequence. At each step, it collects sensory information, updates an internal model of the world and determines the next action based on the model. 
* The robot operates in a top-down fashion, heavy on planning.
* The robot senses the world, plans the next action, acts; at each step the robot explicitly plans the next move.
* All the sensing data tends to be gathered into one global world model.

[[Image:Hierarchical.png|frame|none|Hierarchical Paradigm schema]]

==The reactive paradigm==
{{main|Reactive planning}}The reactive paradigm describes a '''bottom-up''' control structure in which the robot's actions emerge form direct interactions between the robots senors and behaviours, without relying on a central plan or world model.
* Sense-act type of coupling.
* The robot can have multiple instances of Sense-Act couplings.
* These couplings are concurrent processes, called behaviours, which take the local sensing data and compute the best action to take independently of what the other processes are doing.
* The robot will do a combination of behaviours.

[[File:Reactive 2.png|frame|none|Reactive Paradigm schema]]

==Hybrid deliberate/reactive paradigm==
The hybrid paradigm combines elements of both the behaviours and reactive approaches. The robot first plans (deliberates) how to decompose a task into smaller subtasks and selects suitable behaviours to accomplish each one. Once planning is complete, these behaviours execute concurrently following the reactive paradigm.
* The robot first plans (deliberates) how to best decompose a task into subtasks (also called “mission planning”) and then what are the suitable behaviours to accomplish each subtask.
* Then the behaviours starts executing as per the Reactive Paradigm.
* Sensing organization is also a mixture of Hierarchical and Reactive styles; sensor data gets routed to each behaviour that needs that sensor, but is also available to the planner for construction of a task-oriented global world model.

[[File:Hybrid Deliberate-Reactive Paradigm schema.png|frame|none|Hybrid Deliberate/Reactive Paradigm schema]]

==See also==
* [[Behavior-based robotics]]
* [[Hierarchical control system]]
* [[Subsumption architecture]]

== References ==
* Asada, H. & Slotine, J.-J. E. (1986). Robot Analysis and Control. Wiley. {{ISBN|0-471-83029-1}}.
* Arkin, Ronald C. (1998). Behavior-Based Robotics. MIT Press. {{ISBN|0-262-01165-4}}.

{{Robotics}}

[[Category:Robot architectures| ]]