## 2 Methods
### Detection Principle and Calculation Method  
The two main feed detection devices were torque sensors and Hall-type speed sensors. The former was used to measure the power shaft torque of the tilting conveyor, \(T_{s}\). The latter was used to measure the speed of the main shaft of the cutting platform at \(n_{1}\). Torque strain gauges were pasted in the 45 and \(-45^{\circ}\) directions along the tilted conveyor's power axis. Adjacent strain gauges were arranged at \(90^{\circ}\) equal intervals. Figure 2 shows the principle of torque sensor detection. When the harvester is in operation, the  
Figure 1: Sensor installation location diagram: 1: active shaft sensor for cutting platform, 2: screw conveyor shaft sensors, 3: tilt conveying active shaft sensor, 4: threshing drum active shaft sensor. power shaft of the tilting conveyor will deform to different degrees with the change in feeding volume. The resistance of the strain gauge will then change, causing the output voltage to change. The output voltage signal of the bridge will convert to digital signals through the signal amplification and acquisition circuit, and will then be output to the industrial control machine. The power shaft torque is obtained by measuring the voltage signal. Several magnets were attached to the side of the main shaft of the cutting platform. When the main shaft rotated, the Hall effect occurred when the magnets alternately passed through the Hall element, forming a pulse signal. The number of pulses generated per unit of time and the number of magnets on the surface of the main shaft can be used to calculate the corresponding speed of the main shaft of the cutting platform \(n_{1}\). The calculation formula for the speed of the power shaft of the tilting conveyor \(n_{s}\) is as follows:  
\[n_{s}=kn_{1} \tag{1}\]  
where \(n_{s}\) is the speed of the harvester tilting conveyor power shaft, r/min; \(k\) is the transmission ratio between the tilt conveyor power shaft and the main shaft of the cutting platform; and \(n_{1}\) is the speed of the cutting platform active shaft. The formula for calculating the power shaft of a harvester tilt conveyor is as follows:  
\[P_{s}=\frac{T_{s}n_{s}}{9550} \tag{2}\]  
where \(P_{s}\) is the power of the power shaft of the harvester tilt conveyor, kW; \(T_{s}\) is the torque of the harvester tilting conveyor power shaft, N-m. Figure 3 shows a schematic diagram of the operation of the combine harvester tilt conveyor. Figure 3: Working diagram of combine harvester tilt conveyor: 1: crossbar strip chain rake, 2: tilt conveyor active shaft, 3: tilting conveyor bottom plate, 4: straw, 5: threshing drum, 6: concave plate. Figure 2: Schematic diagram of the torque sensor detection principle. R1-4 represent torque strain gauges. Assume that the tilt conveyor feeding volume at the moment t is \(q\) (kg/s). Through the chain rake, the active shaft of the inclined conveyor exerts a traction force on the grain that is \(F\) (N). The pressure on the grain is \(M\) (N). For the analysis of the tilting conveyor in the grain force, it can be seen that, in order to make the grain along the conveyor bottom plate display an upward movement, the following conditions must be met:  
\[F\geq mgsina+\mu(M+mg)cos\alpha \tag{3}\]  
where \(\alpha\) is the inclination angle of the inclined conveyor, rad; \(\mu\) is the friction factor between the grain and the bottom plate of the conveyor; and \(m\) is the mass of the grain conveyed by the conveyor, kg. \(m\) is calculated as follows:  
\[m=a_{p}ln_{p}\gamma \tag{4}\]  
where \(a_{p}\) is the width of the conveyor, m; \(l\) is the length of the conveyor, m; \(h_{p}\) is the average thickness of the material in the down-strike chain rake conveyor, m; and \(\gamma\) is the density of the transported grain layer, kg/\(m^{3}\).