## 4 Simulation Analysis
### Simulation Model  
AMESim is used to establish the simulation model of the loader electro-hydraulic composite braking system shown in Figure 4. It contains four submodules: intention recognition and braking force distribution module (IRBFDM), regenerative braking system module (RBSM), hydraulic braking system module (HBSM), and walking power system module (WPSM). According to the vehicle driving data, IRBFDM recognizes the current driver's braking intention and braking intensity to make the decision of electro-hydraulic braking force distribution. RBSM receives the motor regenerative braking torque signal and complete energy saving and braking through WPSM. HBSM receives the brake pedal displacement signal and outputs the oil to the brake wheel cylinder. HBSM participates in the whole vehicle braking process.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Device** & **Parameter Name/Unit** & **Value** \\ \hline \multirow{4}{*}{Loader} & Vehicle weight/kg & 18,500 \\  & Rated load/kg & 5000 \\  & Walking & Forward I/II & 12/32 \\  & speed/(km/h) & Reverse I & 24 \\ \hline \multirow{4}{*}{Walking mechanism} & Tire radius/m & 0.808 \\  & Motor power/KW & 110 \\ \cline{1-1}  & Motor torque/N-m & 1050 \\ \cline{1-1}  & Battery stored power/W & 282 \\ \cline{1-1}  & Battery maximum continuous discharge current/A & 250 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Basic parameters of a 5-ton electric loader.  
Figure 3: Flow chart of braking force control strategy distribution for electro-hydraulic composite braking system.  
where the following definitions apply.  
IRBFDM: The input of the IRBFDM model mainly includes the vehicle speed, accelerator pedal displacement, brake pedal displacement, hydraulic brake pressure, motor speed, power battery SOC and other state parameters from the vehicle. The displacement of two pedals is obtained through the differential module, and the intention recognition and intensity recognition are carried out through the fuzzy controller and fuzzy rules. Among them, when the accelerator pedal is released for deceleration intention recognition or coasting brake intention recognition, if the brake pedal is not pressed within 1.3 s of the interval between the accelerator pedal and the brake pedal action, the deceleration intensity obtained by the deceleration intention recognition is maintained within 1.3 s, and the output of the coasting brake intensity is transitioned after 1.3 s. The output of the four intention recognition modules is finally synthesized into the vehicle strength output, and the vehicle braking torque demand is calculated through the vehicle braking strength.  
RBSM: During regenerative braking, the signal input to the motor is the regenerative braking torque signal calculated by the IRBFDM. The regenerative braking torque is transmitted to the vehicle through the connection with the reducer. The two outputs of the motor are connected to the positive and negative terminals of the power battery which store the regenerative braking energy. The two ports of the power battery are, respectively, the working voltage signal and the battery SOC.  
HBSM: As shown in Figure 2, the brake valve is mechanically connected to the brake pedal. And in simulation, a proportional electromagnetic reversing valve is used to simulate the brake valve and convert the brake pedal displacement into a current signal.  
WPSM: The power output of the motor is transmitted to the front and rear wheels through the gearbox, the front and rear drive axle, and the wheel rim. The tire model can receive the force and speed transmitted by the vehicle body, receive the torque of the hydraulic braking system and the power system, and interact with the road model to convert the above physical quantities into the force between them and the road, surface. Then, the road condition is fed back to the vehicle.