# Driverless Bus Path Tracking Based on Fuzzy Pure Pursuit Control with a Front Axle Reference
## 5 Conclusions  
A path-tracking controller for a driverless bus is proposed. On this basis, path-tracking is divided into lateral and longitudinal control. Firstly, in lateral control, a path-tracking controller based on FPPC-FAR is indicated. Meanwhile, the reference point of PP is moved from the rear axle to the front axle. It relieves the influence of bus's lateral dynamic characteristics to path-tracking. Additionally, a fuzzy logic inference machine is adopted to adjust the parameter of PPC-FAR, which improves the tracking accuracy of PPC-FAR. Secondly, in longitudinal control, a feedback-feedforward control algorithm is proposed. In feedback control, TD is introduced to calculate the fast tracking of the desired  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Parameters**} & \multicolumn{3}{c}{**Feedback Control**} & \multicolumn{3}{c}{**Feedforward Control**} \\ \cline{2-6}  & \(\mathbf{r}\) & \(\mathbf{h}\) & \(\mathbf{k_{P}}\) & \(\mathbf{k_{i}}\) & \(\mathbf{k_{v}}\) \\ \hline value & 4 & 0.01 & 0.23 & 0.0015 & 0.05 \\ \hline \hline \end{tabular}
\end{table}
Table 6: Parameters of longitudinal control for real bus experiments.  
Figure 22: Results of real driverless bus experiments. (**a**) Desired path and actual path of bus. (**b**) Steering angle and lateral error. (**c**) Desired velocities and feedback velocities. (**d**) Deceleration and longitudinal error.  
velocity, which highly improves the input quality of PI. Then, a PI controller is built to track the fast tracking of the desired velocity, which increases the efficiency of longitudinal control. In feedforward control, the component of gravity is applied as the compensation of deceleration, which relieves the influence of the driverless bus's gravity on longitudinal control. Simulations and real bus experiments indicate the advantages of the path-tracking controller, which is proposed in this paper.  
Additionally, the main idea for driverless bus path tracking is only a preliminary work. For making full use of the advantage of those path-tracking algorithms, more accurate driverless bus models should be built in the future. Furthermore, the relationship between the bus performances and the parameters of the path-tracking controller should be clear, too.  
Conceptualization: L.Y.; formal analysis: X.Y.; funding acquisition: L.Y.; methodology: L.Y., X.Y. and Z.K.; resources: Z.K.; software: X.Y. and Z.K.; supervision: B.C. and Y.Z.; validation: X.Y.; visualization: L.Y.; writing--original draft: X.Y. All authors have read and agreed to the published version of the manuscript.  
This work was supported by National Natural Science Foundation of China under grant 61976224 and 61403426, National Key Research and Development Program of China under grant 2018 YFB1201602, Major Projects of Science and Technology in Hunan under grant 2017 GK1010, and in part by Natural Science Foundation of Hunan under grant 2018 JJ2531 and grant 2018 JJ2197.  
The authors declare no conflict of interest. The funders had no role in the design of the study, in the collection, analyses, or interpretation of data, in the writing of the manuscript; or in the decision to publish the results.