# Braking Intention Identification Strategy of Electric Loader Based on Fuzzy Control
## 3 Fuzzy Controller Design
### Deceleration Intention Identification Based on Accelerator Pedal  
The status of the accelerator pedal can reflect braking demand to a certain extent. The deceleration intentions are divided into mild deceleration intention, moderate deceleration intention, and strong deceleration intention. It is easy to misjudge whether to decelerate only on the displacement change rate of accelerator pedal, so the accelerator pedal displacement limit is introduced which is defined as Sf. When it is less than the limit value Sf, the driver's intention is judged as deceleration braking. The identification process is shown in Figure 2.  
The slight shaking of the driver's foot when stepping on the accelerator pedal will cause a slight change in the displacement of the accelerator pedal, which is not the driver's intention reaction. Therefore, the membership function of O is added in this paper, indicating that the braking strength is 0 when the intention is in the range of O. According to the deceleration data generated by the electric loader driving under different working conditions, combined with the rule that the smaller the speed, the stronger the intention, the deceleration intention is divided into zero intention, small intention, low intention, medium intention and high intention, which are successively defined as O, S, L, M and H. And, the domain of deceleration intention is [0, 1]. In actual driving condition, both the pedal displacement and pedal speed stepped on by drivers are not fixed even if under the same driving intention, which change within a range. Therefore, it is more suitable to the actual driving condition by using the trapezoidal upper-base as the fluctuation range of pedal speed and displacement under the same driving intention. In addition, the trapezoidal membership function calculation is simple and efficient relatively, and the fuzzy control can be realized in practical application with low calculation and time costs. Therefore, the trapezoidal membership function is chosen for most intentions or strengths in this paper. Both in the domain of O and S, the deceleration intentions are very small or even zero, so it is more appropriate to use the triangular function to describe the member function of O and S.  
Combining with the rules and the engineering experience, the ranges of deceleration intentions are divided. Because of the deceleration intention domain is [0, 1] by the experiment data, the partition range of O is [0, 0.0156, 0.0312], the partition range of S is [0, 0.1, 0.2], the partition range of L is [0.15, 0.25, 0.3, 0.4], the partition range of M is [0.3, 0.5, 0.55, 0.7], and the partition range of H is [0.65, 0.9, 1, 1], respectively. Because there is a certain fuzziness in the division of intention, each intention have a small part of the intersection. In order to enhance the identification sensitivity of deceleration intention under high speed and emergency braking conditions, the range of left-diagonal is large when dividing the deceleration intention of H. The membership functions of deceleration intention are shown in Figure 3.  
Figure 2: The identification process of deceleration intention and deceleration strength. The raise speed of the accelerator pedal represents the driver's intention to decelerate, so the deceleration intention fuzzy rules are formulated combined with the raised speed of the accelerator pedal as shown in Table 2.  
According to the experiment data, the braking strength is obtained under different speed conditions and different intentions, correspondingly. The adjustment is made according to the rule that the higher speed, the greater intention strength demand. The deceleration strength is divided into very low deceleration strength, small low deceleration strength, low deceleration strength, medium deceleration strength, high deceleration strength, and very high deceleration strength, which are successively defined as VS, SL, L, M, H, and SH.