Road surface in CarSim.

<p>Road surface in CarSim.</p

The process of GRNN establishment.

<p>The process of GRNN establishment.</p

Structure of the hybrid estimator for TRFC.

<p>Structure of the hybrid estimator for TRFC.</p

Tire-road friction coefficient estimation.

<p>(The red dotted line is estimated value; continuous black line is reference value).</p

Vehicle parameters.

<p>Vehicle parameters.</p

Block diagram of the proposed hierarchical estimator.

<p>Block diagram of the proposed hierarchical estimator.</p

Slip ratio and slip angle estimation results.

<p>(The red dotted line is estimated value; continuous black line is reference value).</p

Target velocity in CarSim.

<p>Target velocity in CarSim.</p

GRNN architecture used for the TRFC estimation.

<p>GRNN architecture used for the TRFC estimation.</p

Relationship between slip ratio and normalized longitudinal tire force under different friction coefficients.

<p>Relationship between slip ratio and normalized longitudinal tire force under different friction coefficients.</p