## 5 Simulation Research
### Speed Segmented Flow Control Simulation
#### 5.1.2 Flow Control Simulation of Multi-Actuators  
Handle 1 controls the maximum flow of the oil circuit at 160 L/min, and handle 2 controls the maximum flow of the oil circuit at 80 L/min. A 1 MPa load is added to oil circuit 1 and oil circuit 2, respectively. To analyze the flow matching of the electric motor-variable speed control system when multiple actuators move and the flow saturation when the target flow is higher than the maximum flow of the system, the multi-actuators flow control simulation of the system is carried out. The input curve of ratios of target flow to a maximum flow of handle 1 and handle 2 is shown in Figure 11.  
During 0-5 s, handle 1 and handle 2 remain in the middle position, and the ratios of target flow to maximum flow are 0.  
During 5-7 s, the ratio of target flow to the maximum flow of handle 1 increases linearly from 0 to 0.25, and the ratio of target flow to the maximum flow of handle 2 remains 0.  
During 7-27 s, the ratio of target flow to the maximum flow of handle 1 increases linearly from 0.25 to 1, and the ratio of target flow to the maximum flow of handle 2 increases from 0 to 1.  
During 27 to 30 s, the ratios of target flow to the maximum flow of handle 1 and handle 2 remain 1.  
The displacement of the variable displacement pump, electric motor speed, and hydraulic system flow is obtained and given in Figure 12.  
Figure 11: Multi-handles input signal.  
During 0-5 s, the ratios of target flow to the maximum flow of handle 1 and handle 2 are 0. The estimated flow of the system is 0 L/min. The electric motor is 500 rpm. The pump is at the minimum displacement of 8 mL/r. Therefore, the actual hydraulic system overflows with a minimum flow of 40 L/min.  
During 5-7 s, the ratio of target flow to the maximum flow of handle 1 increases linearly from 0 to 0.25. The ratios of target flow to the maximum flow of handle 2 remain 0. At this time, the estimated flow of the system increases from 0 to 40 L/min. This stage is in the variable displacement stage of the variable displacement pump. The pump displacement increases from 8 to 80 mL/r, which can meet the flow demand of the system. Therefore, the electric motor keeps running at 500 rpm, and the actual flow of the system is 40 L/min, all of which flows into the oil circuit of the actuator.  
During 7-19 s, the ratio of target flow to the maximum flow of handle 1 increases linearly from 0.25. The ratio of target flow to the maximum flow of handle 2 increases linearly from 0, and the estimated flow increases linearly from 40 to 160 L/min. The target speed of the electric motor increases from 500 to 2000 rpm. According to the speed segmented control strategy of electric motor speed, the electric motor speed starts from 500 rpm and runs at 1000 rpm, 1500 rpm, and 2000 rpm successively, and the system flow from 40 to 80 L/min, 120 L/min, and 160 L/min successively. The pump displacement shall be kept at the maximum displacement of 80 mL/r.  
During 19-27 s, the estimated flow of the system at 19 s reaches the maximum flow of the system, which is 160 L/min. At this time, the motor speed reaches and remains at the maximum speed of 2000 rpm, the variable displacement pump remains at the maximum displacement of 80 mL/r, and the system is in the flow saturation stage. The ratio of target flow to the maximum flow of pilot handle 1 and pilot handle 2 continues to increase linearly to 1, the estimated flow increases linearly to 240 L/min, and the actual system flow remains at 160 L/min.  
During 27 to 30 s, the ratios of target flow to the maximum flow of both handles are kept at 1. The pump displacement is kept at the maximum displacement of 80 mL/r. The electric motor speed is kept at the maximum speed of 2000 rpm. The actual system flow is kept at the maximum flow of 160 L/min.