Dynamically Simulated Characters in Virtual Environments
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Movies from our 1997 Siggraph Animation Sketch
Slides from our 1997 Siggraph Animation Sketch
The photos below illustrate some of the physical components of the bike
platform hardware. The bike platform was designed and constructed by
In this image it is pitched forward the maximum amount. The platform is
balanced such that when it is not actively controlled, it moves to a
The bike is supported upon the wooden platform by a CompuTrainer stand.
We also use the load generator provided by CompuTrainer. There is a serial
connection between an SGI Indy and a Motorola 68332 microcontroller. The
68332 controls the load generator to increase the difficulty of pedaling.
You might be able to detect from the image that we replaced the blue
freewheel that CompuTrainer attached to the load controller with
a bigger wheel.
The front wheel of the bicycle sits in a medal trough that rotates about
a point in line with the bicycle's headset. An optical encoder measures
the amount of rotation of the front wheel between +/- 20 degrees. The
optical encoder is connected to the 68332, which uses a serial connection
to communicate with the SGI Indy.
The pitch of the bike platform is actively controlled by a motor positioned
in the center the platform. The motor provides transport through the full
range of motion in about 2 seconds. The output of the motor is controlled
by the Motorola 68332.
The final piece of the system is a Motorola 68332. We use this hardware to
read three analog ins, and to write two analog outs. The hardware performs
analog to digital pulse-width modulation and digital to analog pulse-width