Notes on robot design - see also lirec notes & category robotics.

Robotics is the intelligent connection of perception to action“ - Michael Brady

  • Perception: Sensors tell a robot about the outside world.
  • Action: Actuators allow a robot to change the outside world, to act upon it.
  • Intelligence: Some sort of controller

State is what the robot collects in order to understand the world.

(not too happy about these definitions…)

  • Internal state: Directly observable state of the robot. Also it's internal representation of the world - it's internal model.
  • External state: What's happening in the real world. Can only be known via a robot's sensors.
  • Observable state: known at all times, usually internal - eg. battery state.
  • Partially observable state: Through a sensor, along with noise eg: camera image pixels
  • Hidden state: What you are actually interested in, in the real world - eg: position of user's head. Can't be directly known, must be indirectly inferred from (maybe multiple) sensors. See sensor fusion.

Deliberative vs Reactive

Think hard - then act!

  • Capable of learning and prediction
  • Finds strategic solution


  • Requires lots of computation - eg. brute force search for potential plan
  • Needs a world model
  • Slow

For example : Shakey, the first robot built with a planning AI system (running on a PDP-10 and PDP-15 computer).

Don't think, react!

  • Fast
  • Powerful, biological parallel


  • Minimal state
  • No memory
  • No internal representation of the world
  • Unable to plan ahead
  • Unable to learn

For example: BEAM robots which stands for Biology, Electronics, Aesthetics, Mechanics, and was originally invented by Mark Tilden.

Or do both!

  • Deliberative system on top
  • Reactive underneath
  • Hybrid or Behavioural system
  • robot_design.txt
  • Last modified: 2009-01-07 15:05
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