## 5 Simulation Analysis  
According to the operation principle of the boom pump-controlled hydraulic cylinder system and the requirements of the boom load condition, the simulation model of the composite pump-controlled hydraulic cylinder system was built and applied to the excavator working device to drive the hydraulic system, as shown in Figure 13.  
In this paper, MATLAB2017a and AMESim21 were selected, and Visual Studio 2013 was used as the compilation language. Co-simulation also required the corresponding software installation sequence and software, which was completed according to this sequence: Visual Studio 2013, AMESim, MATLAB2017a. According to the working principle of the boom compound pump-controlled hydraulic cylinder, the hydraulic system simulation model is built in AMESim, as shown in Figure 14. The data interaction with Simulink is carried out through the co-simulation interface to realize the co-simulation. The load-power signal of the boom hydraulic cylinder and the displacement signal of the hydraulic cylinder are the input signals of the co-simulation  
Figure 12: Optimal speed rule for different load powers. Figure 13: Combined pump-control system of excavator motor arm. interface. The motor's speed signal of the motor and the displacement control signal of the hydraulic pump are the output signals of the co-simulation interface. The main parameter settings of the system simulation model are shown in Table 3.  
A composite-control strategy model was developed in Simulink. As illustrated in Figure 15, the S-Function module serves as the data interface for exchanging information with AMESim to facilitate the co-simulation. The input signals include the motor speed control and hydraulic pump displacement control signals, while the output signals consist of the hydraulic cylinder displacement and load-power signals. Using the operational principles of the boom compound pump-controlled hydraulic cylinder system, a simulation and an analysis of the speed and displacement compound-control strategy was conducted through AMESim-Simulink co-simulation. The response characteristics, energy-saving attributes, and applications under typical working conditions of the mining boom were examined in detail. For assessing system-response characteristics, sinusoidal displacement control signals at varying frequencies and step-displacement control signals at different magnitudes were input into the boom complex pump-controlled hydraulic cylinder system. The dynamic tracking performance of the system's displacement control signal and its dynamic response performance to these displacement signals were evaluated. Additionally, various load forces on the hydraulic cylinder were established to implement motor speed-matching control strategies under differing load conditions. Figure 14: Simulation model of the hydraulic system of boom compound pump-control cylinder. 1—Hydraulic oil model; 2—Joint simulation interface; 3—Speed conversion; 4—Variable-displacement hydraulic pump; 5—Accumulator; 6-1, 6-2 Hydraulic control check valve; 7-1,2 Relief valve; 8—Boom cylinder; 9—Speed sensor ; 10—Force sensor; 11—displacement sensor; 12—Load. \begin{table}
\begin{tabular}{c c} \hline \hline
**Item** & **Numerical Value** \\ \hline variable pump maximum displacement (mL/r) & 25 \\ \hline rated torque of the motor (Nm) & 80 \\ \hline rated motor speed (r/min) & 2000 \\ \hline rated power of the motor (kW) & 15 \\ \hline hydraulic cylinder bore (mm) & 40 \\ \hline hydraulic cylinder rod diameter (mm) & 25 \\ \hline accumulator volume (L) & 6 \\ \hline accumulator pre-charge pressure (bar) & 15 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Main parameters of the pump-control system. These were applied to the driving system of the excavator working device, combined with the action requirements of the excavator, which completed the system simulation. Figure 16 illustrates three control methods for simulating the boom's typical mining operation period.