Robot Mechanisms and Mechanical Devices Illustrated - Profe Saul

Chapter 4 Wheeled Vehicle Suspensions and Drivetrains 151
Figure 4-22 Six wheels, all
fixed, skid steer, offset center axle
An even trickier layout adds two pairs of four-bar mechanisms supporting
the front and rear wheel pairs (Figure 4-23). These mechanisms
are moved by linear actuators, which raise and lower the wheels at each
corner independently. This semi-walking mechanism allows the vehicle
to negotiate obstacles that are taller than the wheels, and can aid in traversing
other difficult terrain by actively controlling the weight on each
wheel. This added mobility comes at the expense of many more moving
parts and four more actuators.
Skid steering can be improved by adding a steering mechanism to the
front pair of wheels, and grouping the rear pair more closely together.
Figure 4-23 Six wheels, all corner
wheels have adjustable
height, skid steer