08. TrackMeNot [Jacky Yip]


The TrackMeNot experience centers around an interactive toy that always keeps track of where you are. No matter where you spin the toy to, it will always come back around to face you. The only way to keep it away is to shine a light on its forehead. Only then does it get scared and scramble away. However, it eventually comes back if it does not see the light anymore.

Download CHI Extended Abstract Paper: JYip-MTI-Paper

Demo Video


The idea came from the initial project proposal Navi. The goal of Navi was to provide an alternative method in giving directions to people by considering the navigational device as a companion. Due to the lack of integration with a GPS module, Navi felt incomplete as a navigational device. As a result, I was searching for a new way to create a tangible and engaging experience that can take advantage of the Navi system, and I came up with TrackMeNot.

How TrackMeNot Works

a) The toy is facing the user. b) User turns it away. c) The toy rotates its head to face the user again.

The interactive toy loosely simulates face tracking by using a digital compass. First, the user holds the toy in their hands and positions it such that the user and the toy are facing each other. Then, the user instructs the toy to record the current direction in which it is facing. Afterwards, the toy remembers the direction and will always return to it no matter how the user spins the toy around. This direction tracking creates the illusion that the toy is aware of where the user is. It loosely simulates face tracking without the need for computer vision.

When the user shines a light on the toy’s forehead, it activates the photoresistor. The toy becomes scared and tries to shy away from the light by rotating its two servos frantically.

TrackMeNot Construction

The TrackMeNot toy consists of:

The continuous servo motor acts as the torso of the toy, with the regular servo motor mounted perpendicular to its horn using the pan and tilt kit. A metal bracket is attached to the horn of the regular servo motor which acts as the toy’s head.

An infrared proximity sensor acts as the toy’s eyes. Although proximity sensing is not enabled for the current iteration, it can be used in the future so that the toy is aware of its surroundings. Interesting interactions can be implemented such as the toy greeting passersby with a nod when strolling down the street.

The digital compass is attached to the head to provide navigational capabilities.

Lastly, all sensors and actuators are connected to the Arduino board through a mini breadboard. The Arduino board receives input from the digital compass to controls the rotations of the servos.

Each sensor and actuator requires at least three wire connections, leading to a large number of wires. As a result, the wires become difficult to manage in a compact form. In addition, the rotation of the servos can cause the wires to tangle up. To resolve these problems, a XBee module and a coin battery can be added to each sensor and actuator. The XBee module provides wireless capability while the coin battery powers the system. Each XBee chip communicates to a central XBee receiver module attached to the Arduino board.

Schematic Diagram

Arduino Sketch

Arduino Sketch: JackyYip_Navi


TrackMeNot creates an engaging experience that evoked many emotional reactions from its participants. During the demo, five out of eight participants expressed surprise when the toy returned to face them every time they turned it away. All of the participants believed that the toy was able to track their location through face recognition. In addition, when they shined a light on the toy, the toy’s frantic reaction to get away strongly engaged the participants. One participant became protective of the toy by covering the photoresistor with their hand and expressing discontent when their friend continuously shined a light on it.


~ by Jacky Yip on May 12, 2010.

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