Robotic paradigm


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: 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

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.

Hybrid deliberate/reactive paradigm

The hybrid paradigm combines elements of both the behaviours and reactive approaches. The robot first plans 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 how to best decompose a task into subtasks 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.