## 5 Performance Testing of Hydraulic Support FBG Inclinometers  
This experiment is carried out to test the performance of the hydraulic support FBG inclinometer, and to verify the relationship and law between the tilt angle of the fiber grating hydraulic support FBG inclinometer and the grating. The test system consists of a beam with a hinged shaft at one end, a number of pads, an angle gauge, a level, a hydraulic support FBG inclinometer, a network cable, an analyzer and a computer. The demodulator we use is the SM-125 produced by Micron Optics Inc. from the U.S. It is a demodulator  
Figure 8: Diagram of the size of the installation base.  
Figure 10: Design drawing of step hole of hydraulic support.  
Figure 9: Schematic diagram for the use of the installation base.  
based on the core of MOI's x25 demodulator module, with a built-in scanning laser light source developed by MOI's patented tunable Farber filter technology. The FBG fiber grating used in the experiment is produced by Beijing Dacheng Yongsheng Science and Technology Co., Ltd. (Beijing, China), and its upper coating is a polyimide coating material, as shown in Figure 11.  
When carrying out calibration experiments, the following steps need to be strictly followed:  
Step 1: Utilize a spirit level to meticulously adjust the experimental platform to a state of perfect horizontality. Subsequently, carefully position the hydraulic support FBG inclinometer on the beam surface of the platform, guaranteeing that the horizontal axis of the hydraulic support FBG inclinometer is precisely parallel to the axis of the beam. Employ a jumper wire to establish a connection between the hydraulic support FBG inclinometer and the analyzer. The analyzer is then interfaced with a computer to configure the IP settings for the acquisition of monitoring data;  
Step 2 is to adjust the position and height of the pads, and adjust the inclination of the beam with 3\({}^{\circ}\) as one step; meanwhile, measure the corresponding number of inclinations in real time with the angle meter, and record the values of two grating wavelengths in real time so that the hydraulic support FBG inclinometer tilts to the left to reach a 15\({}^{\circ}\) stop;  
Step 2: Manipulate the position and height of the pads. Gradually adjust the inclination of the beam in increments of 3\({}^{\circ}\). Concurrently, utilize a goniometer to measure the corresponding inclination angle in real time. Continuously record the values of the two grating wavelengths, denoted as \(\lambda_{1}\) and \(\lambda_{2}\), in real time. Proceed with this operation until the hydraulic support FBG inclinometer tilts leftward and attains an inclination of 15\({}^{\circ}\). At this juncture, the left-tilting process is terminated;  
Step 3: Rotate the hydraulic support FBG inclinometer in both the left-hand and right-hand directions. Subsequently, re-position the hydraulic support FBG inclinometer on the beam, ensuring with precision that the horizontal axis of the hydraulic support FBG inclinometer aligns exactly parallel to the axis of the beam. Then, reiterate the procedures detailed in Step 1 and Step 2. By carrying out these operations, a comprehensive test range spanning from \(-15^{\circ}\) to \(15^{\circ}\) is established;  
Step 4: The entire suite of operations described above was replicated. Based on the recorded wavelength values of the two gratings, the data were processed and analyzed. Subsequently, the corresponding tilt angles \(\theta\) were determined.