Rack And Pinion
Rack and Pinion steering is the system commonly used in most street vehicles.
The system consists of a toothed beam known as the rack, driven by a small gear known as the pinion. When the gear turns, the rack is displaced. The beam is connected in a parallelogram, with its parallel opposite fixed, and the wheels mounted on its sides.
This steering is fairly intuitive, but has a fairly limited turning circle compared with skid steering. One improvement is to have the system doubled up - so the front and rear wheels each have a rack and pinion driven by one shaft.
Its use in robotics is fairly limited - as although it allows for easy mechanical linkage to a steering wheel for a human, differential or skid steering is more easily achieved under autonomous control.
Variations are possible using simple friction assemblies instead of toothed ones.
Many RC cars use a steering system which looks a little like it - but is simply a servo linkage moving one bar in a parallel.