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This is my second version of
a high mobility wheeled rover designed by the
Autonomous Systems Lab
based in Lausanne, Switzerland.
The major difference of SHRIMP II against my
is its ability to turn.
The vehicle is fully described in my book
Building Robots with LEGO Mindstorms
, and I provide here in this page just some pictures and a short list of its
The front and rear wheel assemblies mount the motor very low, just over
There's a long (joined) axle that crosses all the body of the robot and
operates the front and rear steering together (they obviously turn
opposite). A motor controls the steering.
The RCX has three ports connected: 1 out for the power, 1 out for the
steer, 1 in for the touch sensor that detects the central position of the
For the robot to turn properly, the inner side wheels must be stopped as
in a skid-steer drive. This is achieved using two polarity switches operated
by the rear steering assembly. A rubber keeps them gently pulled in ON
position. The rear wheel pivoting axle as a traverse axle attached to its
top, that during turn pushes also one of the switches. Approaching about 45°
in steering angle, the switch goes off and the connected wheels stop.
It turns well enough. During very large turns all the motors are on but
they can make with the difference in speed. In tighter turns, the inner
wheels stop and the SHRIMP turns around the midpoint of its inner side
It's a bit less robust than my first version. I wouldn't suggest to make
it turn while facing complex and articulated obstacles.
The front wheel has shorter arms to the body (12 instead 16 studs beams)
to compensate with the size of the steering system. This reduces a bit the
maximum height it can climb.