[ewhitman]

Ether is right that the first thing you need to do is plan a path. A polynomial will work find for many situations - you need a 4th order polynomial (y= ax^3+bx^2+cx+d) to fit position and slope at both ends. However, polynomials can give you weird behavior in some situations and can't handle others - you can't get a semi-circle for example.

The math is more complex, but I would recommend looking into splines as a more versatile tool for path planning. Alternately, you could try composing your trajectories entirely of circular arcs and straight segments.

Once you have a path, you can compute the curvature of the path everywhere along it. From the path curvature and the speed, you can compute angular rotation rate (degrees/second). From the rotation rate and the speed, you can get your wheel velocities (using the geometry of your robot).