New library for 2-ServoMotor based movement

I am new to this forum (and Arduino too), but as I've assembled the Parallax Robot Kit into something that moves, I ended up creating a small library that provides some really convenient abstractions for moving a robot that uses two opposite-configured Servos.

I am curious about any feedback, and if something like that is actually useful to others:

The main idea is that that library is the one sending commands to Servo motors individually, which define how many microseconds it should be powered for, while library consumer uses much simpler API to move the robot, like this:

  controller.forward(100, 500); // speed 100%, go for 500ms
    controller.turn(45);          // turn right 45 degrees
    controller.back(50,200)       // go backwards at 50% speed, for 200ms
    controller.turn(-90);      // turn left 90 degrees

Any feedback/comments are welcome!

A library that calls delay() isn't going to be popular...

Look how the AccelStepper library works for a scheme that's compatible with blinkWithoutDelay() style of coding....

Great, thanks for the feedback! I'll check it out.

Phew, that was great feedback, thank you so much!

I updated the library and example, and it's definitely so much better not having any delay() there. I am also now able to integrate a 2-servo arm scanning around with a Sonar installed.

Is there a library like this already by the way? Am I reinventing the wheel?

Quick note that the library has been renamed to BackSeatDriver and now supports two types of cars: 2-servo and 2/4 DC motor.