Realistic wheeled mobile robots do not satisfy the ideal kinematic constraints because of slipping effects at the wheel/ground contact zones. The slow manifold approach allows us to design feedback control laws taking into account these dynamics and ensuring the tracking error of the closed loop system to converge toward zero.
Motte, I., & Campion, G. (2000). A slow manifold approach for the control of mobile robots not satisfying the kinematic constraints. IEEE Transactions on Robotics and Automation, 16(6), 875-880. https://doi.org/10.1109/70.897800 (Original work published 2000)