# Adaptive Cruise Control for Eco-Driving Based on Model Predictive Control Algorithm
## 3 Results and Discussion
Then, a yellow vehicle traveling on the neighboring lane cuts into the lane of the host vehicle, and becomes the newly preceding vehicle. After a period, this newly preceding yellow vehicle changes to another lane so that the original red one becomes the preceding vehicle again. The scenario concept is demonstrated in Figure 11. The proposed ACC system is required to make the reaction to the change in the preceding vehicle on the road. The initial velocity of the host vehicle is assumed to be 20.5 m/s. The simulation results of two control algorithms, ACC based on classic PID controller and ACC based on the proposed MPC controller, are shown in Figures 12-15, and the results for the emissions are reported in Table 3.  
Figure 11: Concept demonstration of scenario 2. Figure 12: Speed response in scenario 2. Figure 6:0 Fuel economy in scenario 1. Figure 6:1 Spacing response in scenario 2. Figure 6:2 Acceleration response in scenario 2. Figure 6:3 Fuel economy in scenario 2. As shown in Figure 14, the preceding vehicle is driving far ahead of the host vehicle in the former 120 s. So, the host vehicle accelerates during this period and reaches the driver set velocity, seen from Figure 6:4 From 120 to around 200 s, the vehicle driving on the neighboring lane cuts into the host vehicle lane, and becomes the newly preceding vehicle. The host vehicle operates at the driver set velocity during around 120 to 150 s, when the spacing between the host vehicle and the preceding vehicle is large. However, from 150 to 200 s, the spacing is reduced, and then the host vehicle decelerates its speed to maintain safe spacing from the preceding vehicle, which is shown in Figure 6:5 During 200 to 340 s, the preceding vehicle again changes its lane, and the original vehicle becomes the preceding vehicle again, which can be seen from Figure 6:6 At this time, the spacing between the two vehicles is large, so the host vehicle accelerates to reach the driver set velocity. According to Figure 13, the acceleration response of the MPC-based ACC system shows a smoother transient behavior indicating that the driving comfortability performs better for the MPC-based ACC system compared to the PID-based ACC system. Figure 15 represents the fuel economy for two controllers. The fuel economy of the PID-based ACC system finally stabilized at 8.2 L/100 km, and in contrast, the fuel economy of the MPC-based ACC system is finally maintained at 7.1 L/100 km, which means that an improvement of 13% in fuel is achieved in this driving scenario. In summary, through the above analysis, the proposed MPC-based ACC system performs better driving comfortability in contrast with the classic PID-based ACC system. In terms of following and driving safety, both are guaranteed by two different controllers. As far as the performance of eco-driving is concerned, it is apparent that the MPC-based ACC system can reduce fuel consumption compared with the classic PID-based ACC system. To justify the proposed MPC-based ACC system, the comparison between the proposed MPC-ACC system in this research and other standard models implemented on commercial production vehicles such as the PID-based ACC system and fuzzy logic control (FLC)-based ACC system are summarized and discussed. Under the standard ACC system, the host vehicle accelerates to the driver set velocity and cruises until it detects the preceding vehicle, and then it tracks the preceding vehicle, only considering the safe distance [40; 41]. Whereas, the proposed MPC-based ACC system is easy to achieve precise and optimal control with future traveling information. It is capable of realizing the real-time multi-objective control, where the eco-driving, reducing fuel consumption, can be achieved by improving the fuel economy by 12-13%. Compared with the FLC-based ACC system [42], the proposed ACC system can achieve multiple objectives, including car-following, driving safety and comfortability, and fuel economy with fewer parameters to consider.