Parametric interpolation is widely used in robot control. However, traditional NURBS interpolators often encounter issues such as discontinuous feed- rate at block boundaries, truncated curve execution, and unsynchronized tool-tip and attitude interpolation. This paper proposes a high-precision, S-shaped feedrate scheduler alongside an optimization algorithm to compensate truncation error and maintain continuous feed between blocks. We introduce a dual-NURBS interpolation framework for synchronizing robot tool-tip trajectory and attitude. Experimental results demonstrate that the proposed method significantly improves curve execution rate from 0.998752 to 0.999993.