# Research on Ride Comfort Control of Air Suspension Based on Genetic Algorithm Optimized Fuzzy PID
## 6 Conclusions  
Combining the operational characteristics of air springs and the complex nonlinear properties of air suspension systems within the scope of vehicle ride comfort research, an analysis is conducted on the vertical dynamics of the vehicle. This involves simplifying the vehicle model and constructing a 1/4 two-degree-of-freedom vehicle model. Taking into account typical driving conditions, a mathematical model of random road input is established, and a road white noise model is built using MATLAB/Simulink. The study includes determining air suspension system parameters and ride comfort evaluation criteria for analyzing the ride comfort of the suspension system. Integrating PID control methodology, the difference between the ideal vertical vibration acceleration (0) of the vehicle and the actual vibration acceleration is directly fed into the controller. The active control force of the air suspension system serves as the output. Using a trial-and-error method, the PID parameters are continuously adjusted based on control effectiveness to optimize their values. Eventually, the PID controller parameters are determined as follows: \(K_{p}=1\), \(K_{i}=53\), \(K_{d}=0.1\). In Simulink, combining the road input system, air suspension simulation module, and PID control system, a PID-controlled air suspension simulation model is established for simulation analysis. Using fuzzy logic and PID control methods, PID parameters are dynamically optimized based on specific fuzzy rules. The integration of fuzzy reasoning with PID control adjusts parameter values according to system requirements to effectively manage the suspension system. The input signals to this controller are the vehicle's vertical acceleration error \(e\) and its rate of change \(e\). Through processes such as fuzzy inference and parameter adjustment, the controller generates the final output. By adjusting the switching time of electromagnetic valves, the air pressure in the air springs is regulated to adjust the stiffness of the air suspension system, thereby determining the optimal PID parameter values. Using genetic algorithms to optimize the control rules and membership functions of the F-PID controller, the performance indicators of active suspension vehicle body acceleration, suspension deflection, and tire load are normalized by their counterparts under the same conditions of passive suspension. This normalization forms the objective function for genetic algorithm optimization, where the reciprocal of the objective function serves as the fitness function. The genetic algorithm calls the F-PID controller model, with ride comfort indicators inputted as optimization parameters in the main GA program, to obtain the optimal values of F-PID controller parameters. In MATLAB/Simulink, three different controllers were established to implement distinct air suspension control strategies, and the performance of the suspension system was studied through simulation. Time-domain response curves of the air suspension systems were obtained, comparing the effectiveness of fuzzy PID control with and without genetic algorithm (GA) optimization. Post-application of the control strategies, improvements \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Evaluation Criteria** & **Passive** & **Fuzzy PID** & **GA-Fuzzy PID** & \
\begin{tabular}{c} **Percentage of** \\ **Fuzzy PID** \\ **Optimization** \\ \end{tabular} &
\begin{tabular}{c} **Percentage of** \\ **GA-Fuzzy PID** \\ **Optimization** \\ \end{tabular} \\ \hline Vehicle Vertical Acceleration & 2.7638 & 2.0729 & 1.9070 & 25\% & 31\% \\ (m/s\({}^{2}\)) & 0.0611 & 0.0489 & 0.0446 & 20\% & 27\% \\ \hline Dynamic Tire Load & 8.8378 & 8.3959 & 8.1308 & 5\% & 8\% \\ (kN) & 8.8378 & 8.3959 & 8.1308 & 5\% & 8\% \\ \hline \hline \end{tabular}
\end{table} 
Table 9: Test conditions of C-grade road surface at 40 km/h. were observed in various performance indicators of the air suspension system compared to the passive suspension.