CS63 HW7: Braitenberg Vehicles

You should work alone on this assignment. Do an update63 to get the starting point files.

Valentino Braitenberg is a neuroscientist who wrote a book called Vehicles: Experiments in Synthetic Psychology that was first published in 1984. He proposed studying principles of intelligence through a series of successively complex machines, which he called vehicles. The design of these vehicles have a strong biological motivation based on his many years of research on brains. Originally he intended this to be purely a thought experiment, but many of these vehicles can be easily implemented in simple robots. These vehicles demonstrate that even extremely simple mechanisms, when embodied in a robot that is situated in a rich environment, can exhibit surprisingly complex behaviors.

Here are several quotes from his book:

• "We will talk only about machines with very simple internal structures, too simple in fact to be interesting from the point of view of mechanical or electrical engineering. Interest arises, rather, when we look at these machines or vehicles as if they were animals, in a natural environment. We will be tempted, then, to use psychological language in describing their behavior. And yet we know very well that there is nothing in these vehicles that we have not put there ourselves." (page 2)
• "It is also quite easy to observe the full repertoire of behavior of these machines--even if it goes beyond what we had originally planned, as it often does. But it is much more difficult to start from the outside and try to guess internal structure just from observation of behavior. It is actually impossible in theory to determine exactly what the hidden mechanism is without opening the box, since there are always many different mechanisms with identical behavior... A psychological consequence of this is the following: when we analyze a mechanism we tend to over estimate its complexity." (page 20)

The purpose of this assignment is to give you the chance to build your own Braitenberg vehicles. You should create a world and a collection of vehicles that interact in interesting ways. Then you will test out Braitenberg's hypothesis that when we observe a mechanism we tend to over estimate its complexity. To do this you will ask two individuals to watch and describe the behavior of of the vehicles in your world.

• When you do an update63 you will find three files in your cs63/homework/07 directory.
  1. The file BraitenbergWorld.py provides an example of how to create a world that includes a set of robots, which many have different sensory capabilities.
  2. The file Vehicle.py is an example of a brain. In this case, all three robots are running the same brain. However, in your experiment, you may have a different brain for each robot, if you'd like.
  3. The file startup.sh is a shell program to quickly start up pyrobot with all three robots. At the unix prompt type: ./startup.sh. To begin execution, press the Run button in all three pyrobot windows. To end, press the Stop button in all three windows. To shut down nicely, from the Robot menu in each window, choose Unload robot, and then from the File menu, choose Exit.
• Once you understand how the provided example works, begin designing your own Braitenberg experiment.
  • Create a world with multiple robots. You may also add obstacles and multiple light sources to your world. You may look at the source code of other Pyrobot Simulator worlds in the directory /usr/local/pyrobot/plugins/worlds/Pyrobot.
  • Then devise one or more vehicle brains to control the robots. You may use any of the sensors available within the Pyrobot Simulator (such as light, range, stall, etc). In each brain file, describe in an opening comment the vehicle type, the sensors used, and the expected behavior.
  • Be sure to update the startup script to accommodate your experiment.
• In the text file observations.txt, describe what happens when you observe people as they watch and interact with the robots in your world. Be sure that your two observers are not CS majors, although they may be students taking introductory CS classes. Before the experiment, you may explain the capabilties of each robot (what sensors it has and what actions it can take), but you should not describe the mechanism that controls the robots. You may allow them to move the robots around in the world. You will report on their descriptions and analyze their responses. Do they use psychological language to describe the robots' behaviors? Do they over estimate the complexity of the underlying control mechanisms?

Once you are satisfied with your programs and summary of observations, hand them in by typing handin63 at the unix prompt.