Roller Racer
What is it?
Here is a sketch of the Roller Racer.
Here is a picture
of a computer-controlled prototype.
Here is a movie of the prototype
in action (3.6 Mb in MPEG format).
What's the idea?
The rider, on the
seat shown, has to merely oscillate the handle--bars from side--to--side to
generate forward propulsion.
The Roller Racer consists of the seat,
with a pair of idler wheels mounted in its rear
and with an elongated steering arm pivoted to the front of the seat,
with a pair of idler (unactuated, passive) wheels also mounted on it,
on the rear of the pivot axis.
The rider provides the propulsion and steering mechanism of this vehicle,
by swinging, with his arms and feet, the steering arm around the pivot axis
and by leaning his body to the left and to the right, following the swinging
of the arm.
The wheels specify a particular form of interaction
of the articulated body with its supporting plane,
that can be modelled by so-called nonholonomic constraints.
If the front wheel assembly is made to oscillate periodically
around the vertical pivot,
the system can be seen to move!
The motion of the system is due to the interaction of the periodic shape
variation with the nonholonomic constraints.
References:
P.S. Krishnaprasad and D.P. Tsakiris,
"Oscillations, SE(2)-Snakes and Motion Control:
A Study of the Roller Racer".
Available as
Center for Dynamics and Control of Smart Structures (CDCSS)
Technical Report CDCSS TR 98-4, 108 pages,
University of Maryland, College Park, 1998.
Also as Institute for Systems Research (ISR)
Technical Report ISR TR 98-35,
University of Maryland, College Park, 1998.
P.S. Krishnaprasad and D.P. Tsakiris,
"Oscillations, SE(2)-Snakes and Motion Control",
34rd IEEE Conference on Decision and Control,
New Orleans, Louisiana, December 13-15, 1995.
The Roller Racer is a commercially-sold toy
( Mason Corporation,
Brentwood, Tennessee, USA ),
for which W.E. Hendricks was awarded
a U.S. patent (No. 3,663,038) in 1972.
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