Some cars have variable-ratio steering, which uses a rack-and-pinion gear set that has a different tooth pitch (number of teeth per inch) in the center than it has on the outside.

And so, there is the distinction between fixed schedules versus ratios, variable schedules and ratio versus interval.

According as compare of voltage deviation and its variable ratio, optimal control of voltage and current is realized with querying fuzzy control sheet and adjusting adverse variable pulse width.