===== Lab 3: Braitenberg Vehicles =====

{{:public:t-622-arti-11-1:vehicle.jpg|}}

==== Material ====

    * [[http://en.wikipedia.org/wiki/Braitenberg_vehicle|Braitenberg Vehicles]] from Wikipedia;
    * Valentino Braitenberg's book: [[http://www.psych.ucsb.edu/~beall/vehicles.pdf|Vehicles Experiments in synthetic Psychology]] (In PDF format);
    * Braitenberg Vehicle simulator:
      * Link to the [[http://www.ai.rug.nl/~gert/applets/braitenbergJRE/|Java Applet]];
      * Applet [[http://translate.google.com/translate?hl=en&sl=nl&tl=en&u=http%3A%2F%2Fwww.ai.rug.nl%2F~gert%2Fapplets%2FbraitenbergJRE%2Fmanual.html|Commands]];
      * Vehicle's [[http://translate.google.com/translate?js=n&prev=_t&hl=en&ie=UTF-8&layout=2&eotf=1&sl=nl&tl=en&u=http%3A%2F%2Fwww.ai.rug.nl%2F~gert%2Fapplets%2FbraitenbergJRE%2Fmodel.html|Model Description]].

==== Before you Start ====

  * Through the next steps you are going to change several settings into the **Braitenberg Vehicle simulator** , in order to show me the results, you'd better write down the settings required for each step on a separate text document ;-)
  * **NOTE**: in the following steps you will encounter **4** different **vehicles** having the same names as Braitenberg used in his book;
  * This is the **vehicle's model** used in the simulator:\\ {{:public:t-622-arti-11-1:vehicle-model.png|}}

==== Braitenberg Vehicles ====

  - **A Braitenberg Vehicle Simulator**:\\ This [[http://www.ai.rug.nl/~gert/applets/braitenbergJRE/|Java Applet]] is a Braitenberg Vehicle simulator that lets you play around with different **settings**, **vehicles** and **sources**. Start by **loading** the applet, a single light source and a vehicle are loaded by default. Now play with different settings adjusting **sensor weights** or **engine speed** values (in the right-left corner of your screen).\\ You can **''Start''**/**''Stop''** or **''Reset''** the simulation using the buttons below the vehicle image;
  - **Vehicle 2a: "Fear"**.\\ This vehicle has two sensors connected in **ipsilateral** (same side) way. The connections are **excitatory**, which means the more light hits the sensor the more faster the associated engine starts. This drives the vehicle faster when it is closer to a source but, for example, when the source is on the right side of it, the right sensor receives slightly more power than the left one. This causes the right engine running faster than the left one and the vehicle turning away from the source. So, **Vehicle 2a** becomes restless in vicinity of sources and tends to avoid them, escaping until it safely reaches a place where the influence of the source is scarcely felt. Because it seems as if this vehicle is afraid Braitenberg calls it **"Fear"**.\\ Set up **sensor weights** and **engine speed** values in the applet and then start the simulation in order to bring **Vehicle 2a** to life;
  - **Vehicle 2b: "Aggression"**.\\ This vehicle is similar to the previous one, except that the sensors are connected in **contralateral** (crossed) way (but still of **excitatory** type). This changes the behavior of the vehicle: it will turn toward a source and eventually hit it. **Vehicle 2b** is excited by the presence of sources, but resolutely turns toward them and hits them with high velocity, as if wanted to destroy them. Vehicle 2b is **"Aggressive**", obviously.\\ Set up this vehicle in the simulator too.\\ **HINT**: you can add and place a new vehicle in your simulator with the following steps:
     - Select "**''vehicle''**" using the **radio** **button** labeled **"''Mouse Attribute''"** (below the model image);
     - **Double-click** the **''LEFT-MOUSE''** button somewhere in the white area;
     - Drag and Drop it wherever you like. You can grab the newly created vehicle with the **''LEFT-MOUSE''** button and move it around keeping the button pressed, then you can drop it simply releasing the mouse button.
  - **Vehicle 3a: "Love"**.\\ Braitenberg defines Vehicles of **Type 2** as //crude//, they can only be excited by the things they smell (sense) and know no smoothing or relaxing stimuli. We could introduce some **inhibition** (**inhibitory** type vehicle) in sensor connections by switching the sign from **positive** to **negative**. This will let the engine slow down when the corresponding sensor is activated (i.e. when receiving more light close to the source). So it will slow down in the presence of a strong stimulus and race where the stimulus is weak. Vehicle 3a has **ipsilateral** connections and when approaching the source,  will orient toward it and come to rest facing the source. This vehicle likes source in a permanent way, staying close by in quiet admiration from the time it spots the source to all future time. That's why its name is **"Love"**;
  - **Vehicle 3b: "Explorer"**.\\ Vehicle 3b is also of **inhibitory** type, but has **contralateral** connections. It will come to rest facing away from the source (when approaching it) and may not stay there very long, since a slight perturbation could cause it to drift away from the source. This would lessen the source's inhibitory influence, causing the vehicle to speed up more and more as it gets away. For this reason **Vehicle 3b** is an **"Explorer"**, it likes the nearby source all right, but keeps an eye open for other, perhaps stronger sources, which it will sail to...
  - **Extra: setting up your own vehicle **.\\ By now you're only at beginning of this journey into **Braitenberg**'s imaginary universe. You can absolutely keep on traveling by using **your own** vehicle. Play with the different settings and describe with your own words the new kind of vehicle you come up with! ;-)