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overview

trundle v1.2
anatomy
images
behavior

interaction
movement


trundle v1.1
+ anatomy
images
behavior

trundle v1.0
anatomy
images

 

Structure

The primary structural framework of Trundle is made from 3/16 aluminum panels and 1/8 stainless steel rods. Steel counterweights are used for balancing the asymmetric joints. Connections are made with shaft collars. Each of the three sections are attached by a single .25 steel rod, thus making the structure prone to oscillation and vibration. When the sections are not connected with gears, the sculpture is a smooth continuously moving mobile. Abec-5 bearings and the high mass of the counterweights give the sculpture a high inertia which keeps it in motion for a long duration, and as a direct result, a great deal of force is required to stop it from turning. The bearings attached to the wheels on top of the sculpture are not nearly as loose, and the sculpture stops very quickly when pushed left or right.

Actuators

Trundle has three degrees of freedom. Its two cascading servo motors each have a range of movement from 0 to 180 degrees giving it a wide range of motion. A standard DC motor is mounted on the top to provide lateral movement.

Control System

The core of Trundle’s control system is a 68HC11 microprocessor which is situated in a Handyboard, an MIT designed controller board. Trundle’s software for processing input and controlling motors is written in the Interactive C programming language.

Sensors

Trundle senses the world through an array of sensors which allows it to recognize the proximity of nearby people and objects.

Sharp GP2D12 Infrared Ranger
+ continuous distance readings
+ reports the distance as an analog voltage
+ approximately 4 30 detection

Devantech SRF04 UltraSonic Ranger
+ measures a range from 3cm to 3m
+ cone of vision approximately 30 degrees

Eltec 442-3 Pyroelectric Detector
+ high gain detector with integral analog signal processing
+ attached Fresnel lens makes detecting left and right movement possible

Custom Electric Field Sensor
+ large knit fabric integrated with conductive thread acts as electrode
+ op-amp based analog circuitry converts touch into changing voltage.
 
Casey Reas ( reas@media.mit.edu )