to me it looks like you are trying to make a circut-pure robot.it is a robot that uses and,or,nor...eck gates to run dc motors.
unless you know how to controll timers using gate ICs,controlling servos is inpossable.to make one you can program,you use a micro controller. they only cost like 5$,i HIGLY recomend that you simply use the one from the 50$ robot,you can do many more things,ant these microcontrolers are way smaller than the circut you need for a servo,and has only advantages,you simply program it off a PC in code (which isint hard)and can make command changes without rewiring in minutes!