Application of genetic fuzzy immune PID algorithm in cruise control for commercial vehicles

Cruise control when driving downhill is one of the most important functions of commercial vehicles equipped with an auxiliary brake system. A genetic fuzzy immune PID algorithm is proposed to achieve a constant speed in this study. An immune feedback algorithm is used to adjust the proportional coefficient, and the fuzzy algorithm is used to adjust the integral coefficient and the differential coefficient. At the same time, the genetic algorithm is used to optimize the immune parameters to overcome the problem of improper selection of immune parameters, which results in large system overshoot and slow response. Simulation and experiment were also carried out to verify the effectiveness of the algorithm. The results show that the vehicle can keep the speed within ±2 km/h around the target speed. The analyses of lateral kinetic energy and the β phase-plane of both a tractor and a semitrailer indicate that braking stability is good when switching the retarder gear, which means the algorithm has a significant effect.