# Braking Intention Identification Strategy of Electric Loader Based on Fuzzy Control
## 3 Fuzzy Controller Design
### Braking Intention Identification Based on Brake Pedal  
The brake pedal displacement can reflect the braking strength, and the displacement change rate of brake pedal can reflect the degree of braking urgency. Considering the same braking intention needs to reflect different braking strength under different speed conditions, the displacement and displacement change rate of brake pedal are selected to deduce the braking intention through fuzzy control rules. As shown in Figure 5, the vehicle speed is introduced to deduce the fuzzy rules of braking strength too.  
According to the above division rule for the deceleration intention and combining with the braking data generated by electric loader under different working conditions, the brake pedal displacement is divided into zero displacement, small displacement, medium displacement, high displacement and very high displacement, which are successively defined as O, S, M, H and VH, where H and VH are defined to distinguish the emergency intention under other speed and the emergency intention under high speed.  
The different combination data of brake pedal displacement and displacement change rate were collected during the experiment. Considering that the intentions were similar under some combination conditions, the paper divided the braking intention into zero intention, very low intention, low intention, medium intention, high intention and very high intention, which adjusted by actual braking condition. The braking intentions are successively defined as O, VS, S, M, H, and VH. Because of the braking intention domain is [0, 3] by the experiment data, the partition range of O is [0, 0, 0.05, 0.15], the partition range of VS is [0.1, 0.2, 0.3, 0.4], the partition range of S is [0.3, 0.5, 0.8, 1], the partition range of M is [0.8, 1.1, 1.8, 2], the partition range of H is [1.8, 2, 2.3, 2.5], the partition range of VH is [2.4, 2.5, 3, 3]. The membership functions of braking strength are shown in Figure 6 and the fuzzy control rules of braking intention are formulated as shown in Table 4.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Braking Intention** & \multicolumn{5}{c}{**Brake Pedal Displacement**} \\ \hline Displacement change rate & O & S & M & H & VH \\ S (Small) & O & VS & S & M & H \\ M (Medium) & O & VS & M & H & VH \\ H (High) & O & S & H & H & VH \\ \hline \hline \end{tabular}
\end{table}
Table 4: The fuzzy rules of braking intention based on brake pedal.  
Figure 5: The identification process of braking intention and braking strength.  
When dividing the braking strength, the braking intention is considered as the main factor and the speed is considered as the secondary factor. The braking strength is divided into zero strength, very small strength, small strength, medium strength, high strength, and very high strength, which are successively defined as O, VS, S, M, H and VH. The division range of moderate braking strength M is large base on the consideration of the high probability of moderate braking intention M and moderate vehicle speed M. Because of the braking strength domain is [0, 1] by the experiment data, the partition range of O is [0, 0, 0.03, 0.06], the partition range of VS is [0.05, 0.1, 0.15, 0.2], the partition range of S is [0.15, 0.2, 0.4, 0.45], the partition range of M is [0.4, 0.45, 0.65, 0.7], the partition range of H is [0.65, 0.7, 0.8, 0.85] and the partition range of VH is [0.82, 0.9, 1, 1], respectively. The membership functions of braking strength are shown in Figure 7 and the fuzzy control rules of braking strength are formulated as shown in Table 5.