Building Phobot

Phobot has been built using only Lego bricks from a standard Lego Mindstorms NXT set, programmed in the MindStorms environment. An additional RFID sensor by Codatex was used to recognise scary objects tagged with RFID tags.

One motor is used to control most emotional expression by moving its eyebrows and arms. When the eyebrows move up, the arms move either forwards or backwards as well. Some fine-tuning of the joints and eyebrow position is needed to avoid breaking your bot's arms (picture does not show ideal positions). The two other motors are used to move Phobot back and let him spin when Phobot's scared.

An 'anxiety function' controls how scared phobot is. If you show Phobot a scary object, its anxiety suddenly increases and only slowly decreases again. You can speed up the decrease by talking to Phobot in a soft voice and holding its hand. Phobot's programming is based on a combination of a subsumption architecture with a finite state machine to control anxiety levels. Fear responses are randomly generated based on it's internal anxiety state.

The standard Lego sound and button/touch sensors have been used to detect 'comforting' of Phobot by the user. The ultrasonic and light sensors have been included in the model for their aesthetics only.

The user can report his or her emotional status to Phobot using a 'fear thermometer', with different portions of the meter tagged with RFID tags. The current Phobot implementation pauses to 'think' about the user's emotional state, but does not take any action yet.

Phobot's sounds were generated by scaring and recording Henriette. Its heartbeat was generated by modifying the standard Lego humanoid's heart beat.

If you're interested in building a phobot and would like to use its code, let us know. The Phobot Mindstorms/LabView program takes up quite some space compared to most of the standard demos. Due to the limitations of the Lego Mindstorms' brick memory, you will have to delete any other files on the brick.

Complete building instructions will be posted here around April 5th, until then you can contact us using the contact form.

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