<p>Road classification.</p>

Specifically in terms of the vehicle body vertical acceleration the proposed method achieves a reduction of 49.41% compared to the passive suspension and 9.33% compared to the Skyhook method on a Class A road at 60 km/h a reduction of 24.82% compared to the passive suspension on a Class A road at 120 km/h and a reduction of 3.19% compared to the Skyhook method on a Class B road at 60 km/h. Furthermore compared to the traditional Fuzzy control method the proposed method demonstrates superior vibration suppression effectiveness across all evaluated operating conditions achieving significantly lower frequency weighted vertical root mean square accelerations.

Furthermore the power spectral density analysis demonstrates that the proposed method significantly suppresses the low frequency resonance of the sprung mass across varying road conditions compared to the passive Skyhook and Fuzzy methods, further validating its superior broadband vibration isolation capability. This demonstrates that the Twin Delayed Deep Deterministic-based control method for the vehicle semi-active suspension model has the advantages of fast convergence speed and good control effectiveness under road surface excitation.</p></div>