A testing device for a linear displacement sensor and a testing method thereof

Abstract

The present application relates to a kind of linear displacement sensor testing device and its testing method, testing device includes: installation base, including base plate and door vertical board;Moving mechanism, including linear module, inductive sheet and grating ruler, grating ruler is used to measure the position of inductive sheet relative to base plate;Support mechanism, including carrier plate, carrier plate is equipped with long hole and pickup slot;Material pressing mechanism, including pressing plate and lifting drive, pressing plate is opposite up and down with carrier plate.This test device can use pressing plate to press linear displacement sensor and then detect, avoid the movement of linear displacement sensor itself caused by electromagnetic induction in detection process, detection result is accurate, and the efficiency of feeding and discharging is high.Testing method steps include feeding, calibration, error detection and discharging.The present application can be paired to collect the displacement value and signal output value required, then complete multiple error detection, and the detection efficiency is high.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of detection, in particular to a testing device for linear displacement sensor and a testing method thereof. BACKGROUND

[0002] The linear displacement sensor (LPS) is mainly used for detecting the displacement of the steering rack, and calculating the steering angle to provide accurate rear wheel steering control for the vehicle. The working principle of the linear displacement sensor is based on the inductance coupling between the transmitting coil, the target metal slider and the three receiver coils, and the output changes the detection signal. Therefore, the linear displacement sensor belongs to the inductance displacement sensor, and the movement of the detection object will cause the change of the magnetic force in the error detection of the linear displacement sensor, which in turn causes the movement of the linear displacement sensor, so that the accurate measurement cannot be achieved. If the linear displacement sensor is fixed on the carrier plate during the detection process, the tightening screw is relatively slow, which cannot meet the requirements of high-speed detection.

[0003] Chinese patent CN111457875A discloses a multifunctional detection method and device based on linear displacement sensor, which comprises a base, a linear motor, a high-precision grating displacement sensor, a test linear displacement sensor and a main control unit, and the base is fixedly connected with a guide rail; the linear motor comprises a motor rotor movably connected with the guide rail and a motor stator fixedly connected with the base; the high-precision grating displacement sensor and the test linear displacement sensor both comprise a fixed part and a detection probe movably connected with the fixed part, the fixed parts of the high-precision grating displacement sensor and the test linear displacement sensor are fixed in parallel on the base, and the detection probes of the high-precision grating displacement sensor and the test linear displacement sensor are fixedly connected with the motor rotor; the high-precision grating displacement sensor and the linear motor are electrically connected with the main control unit, and the output ends of the high-precision grating displacement sensor and the test linear displacement sensor are electrically connected with a data acquisition unit. Here, the fixed part of the test linear displacement sensor is directly fixed on the base, the detection probe is fixedly connected with the motor rotor, the displacement data is obtained by the high-precision grating displacement sensor through the movement of the detection probe driven by the linear motor, and the corresponding detection signal is output by the detection probe, so this linear displacement sensor belongs to the potentiometer type displacement sensor, and therefore there is no risk of movement of the linear displacement sensor, and the positioning and efficiency problems of the inductance displacement sensor cannot be solved.

[0004] Therefore, it is necessary to provide a special testing device to solve the above problems. SUMMARY

[0005] The main purpose of the present application is to provide a testing device for linear displacement sensor, which has compact structure, can detect the linear displacement sensor by pressing the linear displacement sensor with the pressing plate, avoids the movement of the linear displacement sensor caused by electromagnetic induction in the detection process, and has accurate detection results and high feeding and discharging efficiency.

[0006] The application achieves the above-mentioned purpose by the following technical scheme: a testing device of a linear displacement sensor, comprising:

[0007] a mounting base comprising a base plate and a door upright plate vertically arranged on the base plate;

[0008] a moving mechanism arranged on the base plate, comprising a linear module horizontally mounted on the base plate, a sensing sheet driven by the linear module to move linearly, and a grating ruler arranged on one side of the linear module, the grating ruler being used to measure the position of the sensing sheet relative to the base plate;

[0009] a supporting mechanism arranged on the base plate, comprising a supporting plate, a long hole on the supporting plate matching the moving path of the sensing sheet, and a pickup slot on the supporting plate used to position the linear displacement sensor, the long hole extending through the thickness direction of the supporting plate, and the pickup slot extending to both sides of the long hole;

[0010] a pressing mechanism arranged on the base plate, comprising a pressing plate and a lifting driving element driving the pressing plate to lift, the pressing plate being opposite to the supporting plate in the up-down direction.

[0011] Specifically, the mounting base comprises a base plate, a door upright plate vertically arranged on the base plate, and a plurality of reinforcing ribs connected to the base plate and the door upright plate at an included angle, the door upright plate being a flat plate in a door-shaped structure, the upper part of the door upright plate being fixed with the pressing mechanism, and the lower part of the door upright plate being penetrated by the moving mechanism.

[0012] Further, the linear module comprises an electric cylinder and a moving seat driven by the electric cylinder to move linearly, the sensing sheet being arranged on the upper part of the moving seat, and the electric cylinder penetrating the inside of the door upright plate.

[0013] Further, the supporting mechanism further comprises four air springs and two height limiting columns, the lower ends of the four air springs being seated on the base plate, the upper ends of the four air springs being connected to the four corners of the supporting plate respectively, the two height limiting columns being equal in height and having upper ends connected to the lower surface of the supporting plate, and the two height limiting columns being arranged on both sides of the moving mechanism.

[0014] Further, the lifting driving element is connected to one side of the door upright plate, and the lifting driving element is a sliding table air cylinder.

[0015] Specifically, the pressing mechanism further comprises a pressing frame connecting the lifting driving element and the pressing plate, the pressing plate being arranged at the bottom of the pressing frame, and the pressing plate and the pressing frame constituting a cuboid structure.

[0016] Another main purpose of the application is to provide a testing method of a linear displacement sensor, which can complete the detection of various errors by using the linear displacement sensor testing device.

[0017] A test method of a linear displacement sensor is completed by using any of the test devices, and the steps include:

[0018] S1, feeding: the linear displacement sensor is positioned and placed in the pickup groove, the detection area of the linear displacement sensor is exposed downward from the long hole, then the pressing plate is used to press the linear displacement sensor, and the linear displacement sensor reaches a proper detection distance from the inductive sheet;

[0019] S2, calibration: after the linear displacement sensor is powered on, the inductive sheet moves to the mechanical leftmost position, moves to the mechanical rightmost position at a specified moving speed, in this process, the displacement value x of the inductive sheet is collected by the grating ruler, the linear displacement sensor can simultaneously obtain two signal output values y1 and y2, the changes of (x, y1) and (x, y2) are independently drawn into signal output curves and placed on the same graph, two clamping limit displacement values x a and x b and the limit output values y a and y b corresponding to the two clamping limit displacement values are obtained, then the output clamping is configured, the midpoint of the linear displacement sensor is , , and the signal output theoretical value of the midpoint is ;

[0020] S3, error detection: after the linear displacement sensor is powered on again, the inductive sheet moves to the mechanical leftmost position again, moves to the mechanical rightmost position at a specified moving speed, and collects a group of data (x, y1, y2) at every set distance, y1 is the signal output measured value of the first channel when the inductive sheet 42 is at the x position, y2 is the signal output measured value of the second channel when the inductive sheet 42 is at the x position, then various error calculations are performed;

[0021] S4, discharging: the pressing plate is raised to separate from the linear displacement sensor, and then the linear displacement sensor that has been detected is taken away from the carrier plate.

[0022] Specifically, the calculation method of the total error and the diagnostic error is:

[0023] , ; and

[0024] x 1cal is the calculated value of x according to y1 under the first channel, x 2cal is the calculated value of x according to y2 under the second channel, and k is the x-y conversion coefficient of the linear displacement sensor.

[0025] , ;

[0026] M 1err is the total error under the first channel, M 2err is the total error under the second channel;

[0027] = ;

[0028] is the diagnostic error of the linear displacement sensor.

[0029] Specifically, the calculation method of the slope error is: fitting all (x, ) as the first straight line to obtain the slope g1, fitting all (x, ) as the second straight line to obtain the slope g2, and then calculating the slope error G 1err and G 2err :

[0030] , ;

[0031] g1 is the slope of the first straight line, g2 is the slope of the second straight line, G 1err is the slope error of the first straight line, and G 2err is the slope error of the second straight line.

[0032] Further, according to the first straight line and the second straight line, the displacement fitting value corresponding to x in the first straight line is found first, and then the displacement fitting value corresponding to x in the second straight line is found:

[0033] Then, the nonlinear error N 1err and N 2err are calculated:

[0034] , ;

[0035] is the nonlinear error of the first channel, is the nonlinear error of the second channel.

[0036] The beneficial effects of the technical scheme of the present application are:

[0037] 1. The test device can press the linear displacement sensor with a pressing plate for detection, avoiding the movement of the linear displacement sensor caused by electromagnetic induction in the detection process, and the detection result is accurate and the feeding and discharging efficiency is high.

[0038] 2, The test method can acquire displacement value and signal output value in pairs, and then complete multiple error detections, and the detection efficiency is high. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 Fig. 1 is a perspective view of a test device for a linear displacement sensor according to an embodiment of the present application;

[0040] Figure 2 Fig. 2 is a perspective view of a linear displacement sensor placed on a supporting mechanism according to an embodiment of the present application;

[0041] Figure 3 Fig. 3 is a connection relationship diagram of a mounting base and a pressing mechanism according to an embodiment of the present application;

[0042] Figure 4 Fig. 4 is a connection relationship diagram of a mounting base and a moving mechanism according to an embodiment of the present application;

[0043] Figure 5 Fig. 5 is a detection principle diagram of a linear displacement sensor according to an embodiment of the present application;

[0044] Figure 6 Fig. 6 is a signal output curve diagram after completion of configuration according to an embodiment of the present application;

[0045] Figure 7 Fig. 7 is a conversion principle diagram of a signal output value and a displacement value according to an embodiment of the present application.

[0046] Numerals in the figures represent:

[0047] 100 - test device,

[0048] 1 - mounting base, 11 - base plate, 12 - door upright plate, 13 - reinforcing rib;

[0049] 2 - supporting mechanism, 21 - carrier plate, 211 - long hole, 212 - pickup groove, 22 - gas spring, 23 - height limiting column;

[0050] 3 - pressing mechanism, 31 - pressing plate, 32 - lifting driving part, 33 - pressing frame;

[0051] 4 - moving mechanism, 41 - linear module, 411 - electric cylinder, 412 - moving seat, 42 - sensing sheet, 43 - grating ruler;

[0052] 200 - linear displacement sensor. DETAILED DESCRIPTION

[0053] The present application will be further described in detail below in combination with specific embodiments.

[0054] Embodiment:

[0055] As Figure 1As shown, a testing device 100 of a linear displacement sensor 200 of the present application comprises a mounting base 1, a supporting mechanism 2, a pressing mechanism 3 and a moving mechanism 4, the supporting mechanism 2, the pressing mechanism 3 and the moving mechanism 4 are all arranged on the mounting base 1.

[0056] As shown, Figure 2 The mounting base 1 comprises a base plate 11, a door upright plate 12 vertically arranged on the base plate 11 and a plurality of reinforcing ribs 13 connected to the inside angle of the base plate 11 and the door upright plate 12.

[0057] The base plate 11 is the fixed base of the supporting mechanism 2 and the moving mechanism 4. The door upright plate 12 is a flat plate of door-shaped structure, the upper part of the door upright plate 12 is fixed with the pressing mechanism 3 and the lower part is penetrated by the moving mechanism 4. The reinforcing ribs 13 are used to keep the base plate 11 and the door upright plate 12 in vertical state, so that the whole testing device 100 has enough structural rigidity and the actions between parts are accurate.

[0058] As shown, Figure 1 and Figure 2 The supporting mechanism 2 comprises a supporting plate 21, four air springs 22 and two height limiting columns 23. The supporting plate 21 is provided with a long hole 211 matching the moving path of the sensing sheet 42 and a pickup groove 212 used to position the linear displacement sensor 200, the long hole 211 penetrates through the thickness direction of the supporting plate 21 and the pickup groove 212 extends to both sides of the long hole 211. The lower ends of the four air springs 22 are seated on the base plate 11 and the upper ends are connected to the four corners of the supporting plate 21 respectively. The two height limiting columns 23 are equal in height and the upper ends are connected to the lower surface of the supporting plate 21, and the two height limiting columns 23 are separately arranged on both sides of the moving mechanism 4.

[0059] The supporting plate 21 is a positioning supporting part of the linear displacement sensor 200 and is used to embed the linear displacement sensor 200. The length direction of the long hole 211 is along the length direction of the linear displacement sensor 200 and allows the sensing sheet 42 to translate in a place very close to the lower surface of the linear displacement sensor 200. The four air springs 22 make the supporting plate 21 be smoothly lifted, after the pressing plate 31 presses the upper surface of the linear displacement sensor 200, the four air springs 22 will be compressed synchronously until the lower ends of the two height limiting columns 23 simultaneously contact the upper surface of the base plate 11. Because the moving mechanism 4 has occupied part of the space above the base plate 11, the height limiting columns 23 need to be staggered with the position of the moving mechanism 4 to be able to contact the upper surface of the base plate 11.

[0060] As shown, Figure 3As shown, the pressing mechanism 3 includes a pressing plate 31, a lifting drive 32 that drives the pressing plate 31 to rise and fall, and a pressing frame 33 that connects the lifting drive 32 and the pressing plate 31. The pressing plate 31 and the carrier plate 21 are vertically opposite each other. The lifting drive 32 is fixed to the upper part of the door panel 12 and drives the pressing plate 31 to rise and fall through the pressing frame 33. The pressing plate 31 is located at the bottom of the pressing frame 33, and the pressing plate 31 and the pressing frame 33 form a cubic frame structure. The lifting drive 32 is a slide cylinder.

[0061] The lower surface of the pressure plate 31 is used to clamp the linear displacement sensor 200 vertically against the upper surface of the carrier plate 21. The pressure frame 33 is a component with high structural rigidity, which allows the lower surface of the pressure plate 31 to remain horizontal after being subjected to the reaction force of the linear displacement sensor 200, thereby ensuring that the linear displacement sensor 200 is pressed tightly and preventing the linear displacement sensor 200 from being disturbed during detection and losing its original position. Before loading, the pressure plate 31 needs to be moved to the high position of the testing device 100 to leave enough height space to place the linear displacement sensor 200 on the carrier plate 21. The slide cylinder itself has a directional guiding function, enabling the pressure plate 31 to move accurately in the vertical direction.

[0062] like Figure 4 As shown, the moving mechanism 4 includes a linear module 41 horizontally mounted on the substrate 11, a sensing element 42 driven by the linear module 41 to move linearly, and a grating ruler 43 located on one side of the linear module 41. The grating ruler 43 is used to measure the position of the sensing element 42 relative to the substrate 11. The linear module 41 includes an electric cylinder 411 and a moving base 412 driven by the electric cylinder 411 to move linearly. The sensing element 42 is located on the upper part of the moving base 412. The electric cylinder 411 passes through the interior of the door panel 12.

[0063] The electric cylinder 411 is a modular component of servo motor and screw integrated design, which can convert the rotary motion of servo motor into linear motion of the moving seat 412. The inductive sheet 42 is fixed on the moving seat 412 and translates with the height close to the lower surface of the linear displacement sensor 200, thereby causing the linear displacement sensor 200 to output an induction signal. The electric cylinder 411 occupies the space in the middle of the base plate 11, and the door stand 12 needs to be used to fix the pressing mechanism 3 above the electric cylinder 411, so the door stand 12 needs to have a door structure staggered with it. The grating ruler 43 is used to detect the position change of the inductive sheet 42 in real time (the position of the inductive sheet 42 is represented by the position of the moving seat 412). Therefore, the corresponding data of the signal output value y and the displacement value x of the inductive sheet 42 can be collected, so as to realize the calculation of the correlation performance. The correlation performance includes total error, slope error, nonlinearity, symmetry error and diagnostic error, etc. The test device can press the linear displacement sensor 200 with the pressing plate 31 for detection, avoiding the movement of the linear displacement sensor 200 caused by electromagnetic induction in the detection process, and the detection result is accurate, and the feeding and discharging efficiency is high.

[0064] As shown in Figures 1 to 5 , the test method of the linear displacement sensor 200, the steps include:

[0065] S1, feeding: position the linear displacement sensor 200 on the carrier plate 21 (specifically on the pickup groove 212), so that the detection area of the linear displacement sensor 200 is exposed downward from the long hole 211, and then press the linear displacement sensor 200 with the pressing plate 31, so that the linear displacement sensor 200 and the inductive sheet 42 reach a proper detection distance.

[0066] In this embodiment, the carrier plate 21 is lowered, so that the distance between the linear displacement sensor 200 and the inductive sheet 42 is 0.7mm. In this way, the movement of the inductive sheet 42 can cause the linear displacement sensor 200 to output a signal that changes with the displacement value.

[0067] S2, calibration: after the linear displacement sensor 200 is powered on, the inductive sheet 42 moves to the mechanical leftmost position, and moves to the mechanical rightmost position at a specified moving speed. In this process, the displacement value x of the inductive sheet is collected by the grating ruler 43, and the linear displacement sensor 200 can simultaneously obtain two signal output values y1 (the signal output measured value of the first channel DIE A) and y2 (the signal output measured value of the second channel DIE B). The changes of (x, y1) and (x, y2) are independently drawn into signal output curves and placed on the same graph, as shown in Figure 6 and Figure 7 According to the mutation position of the signal output value, two clamping limit displacement values x a and x b and the limit output values y corresponding to the two clamping limit displacement valuesa and y b Then the output clamping is configured, and the middle of the linear displacement sensor 200 (close to the middle of the long hole 211) is , The theoretical value of the signal output at the position is .

[0068] In theory, there is a fixed offset between the displacement value measured by the grating ruler 43 and the displacement value obtained by the linear displacement sensor 200, and the displacement coordinate obtained by the linear displacement sensor 200 is only in a proportional relationship (proportion x-y conversion coefficient k) with . Because , and are constants, so , the result is a constant value, that is, the same x corresponds to and are complementary within the allowable error range, and from Figure 6 it can be seen that the signal output curve has a clear "platform" in the extension part of the clamping limit, which is the most accurate to measure, so it is necessary to calibrate using clamping limit data.

[0069] S3, error detection: after the linear displacement sensor 200 is powered on again, the sensing sheet moves to the leftmost mechanical position, moves to the rightmost mechanical position at the specified moving speed, and collects a group of data (x, y1, y2) every set distance, y1 is the first channel signal output measured value when the sensing sheet 42 is at the x position, y2 is the second channel signal output measured value when the sensing sheet 42 is at the x position, and then various error calculations are performed.

[0070] First, calculate x 1cal and x 2cal :

[0071] , ;

[0072] x 1cal is the calculated value of x according to y1 under the first channel, and x 2cal is the calculated value of x according to y2 under the second channel, and k is the x-y conversion coefficient of the linear displacement sensor.

[0073] In theory, the x-y curve under the first channel and the x-y curve under the second channel should be a straight line passing through (0, ), and the slope of the former is k and the slope of the latter is -k. However, there will be errors in actual measurement, resulting in and x all have a small error.

[0074] Then calculate the total error M1err and M 2err :

[0075] , ;

[0076] M 1err is the total error under the first channel, M 2err is the total error under the second channel.

[0077] In actual measurement, x is within the measurement interval, each M 1err and M 2err must be within the error range (in this embodiment, between ±0.15mm) to determine that the total error of the linear displacement sensor 200 is qualified.

[0078] = .

[0079] is the diagnostic error of the linear displacement sensor 200.

[0080] In actual measurement, x is within the measurement interval, each must be within the error range (in this embodiment, between ±0.2mm) to determine that the diagnostic error of the linear displacement sensor 200 is qualified.

[0081] According to the least square method, all (x, ) are fitted into the first straight line to obtain the slope g1, and all (x, ) are fitted into the second straight line to obtain the slope g2, and then the slope error G 1err and G 2err are calculated:

[0082] , ;

[0083] g1 is the slope of the first straight line, g2 is the slope of the second straight line, G 1err is the slope error of the first straight line, and G 2err is the slope error of the second straight line.

[0084] Because x≈ , theoretically, the slopes g1 and g2 of the first straight line and the second straight line after linear fitting are both close to 1. Therefore, the difference between the slope and 1 is taken as the slope error value, so as to determine whether the slope error meets the standard.

[0085] Similarly, according to the first straight line and the second straight line, the displacement fitting value corresponding to x in the first straight line is found first, and then the displacement fitting value corresponding to x in the second straight line is found:

[0086] Then the nonlinear error N is calculated 1err and N 2err :

[0087] , ;

[0088] N1 is the nonlinear error of the first channel, N2 is the nonlinear error of the second channel.

[0089] According to and whether within the error range, it is judged whether the nonlinear error is up to standard.

[0090] S4, blanking: the pressing plate 31 is raised, thereby separating from the linear displacement sensor 200, and then the linear displacement sensor 200 which has been detected is taken away from the loading plate 21.

[0091] The test method can pair the required displacement value and signal output value, and then complete multiple error detections, and the detection efficiency is high.

[0092] The above only describes some embodiments of the present application. For those skilled in the art, without departing from the inventive concept, several modifications and improvements can be made, which are within the scope of protection of the present application.

Claims

1. A testing method of a linear displacement sensor, using a testing device, the testing device comprising: a mounting base comprising a base plate and a door stand plate vertically arranged on the base plate; a moving mechanism arranged on the base plate, comprising a linear module horizontally mounted on the base plate, a sensing sheet linearly moved by the linear module, and a grating ruler arranged on one side of the linear module, the grating ruler being used to measure the position of the sensing sheet relative to the base plate; a supporting mechanism arranged on the base plate, comprising a supporting plate, the supporting plate being provided with a long hole matching the moving path of the sensing sheet and a pickup slot used to position and place the linear displacement sensor, the long hole penetrating through the thickness direction of the supporting plate, and the pickup slot extending to both sides of the long hole; and a pressing mechanism arranged on the base plate, comprising a pressing plate and a lifting driving element used to drive the pressing plate to lift, the pressing plate being opposite to the supporting plate in a vertical direction; wherein the testing method comprises the following steps: S1, feeding: positioning and placing the linear displacement sensor in the pickup slot, exposing the detection area of the linear displacement sensor downward from the long hole, and then pressing the linear displacement sensor with the pressing plate to make the linear displacement sensor reach a proper detection distance from the sensing sheet; S4, discharging: lifting the pressing plate to separate from the linear displacement sensor, and then taking the linear displacement sensor which has been detected away from the supporting plate; and the calculation method of the total error and the diagnosis error is: x-y. The mounting base comprises a base plate, a door stand plate vertically arranged on the base plate, and a plurality of reinforcing ribs connected to the base plate and the door stand plate at an included angle, the door stand plate is a flat plate in a door shape, the upper part of the door stand plate is fixed with the pressing mechanism, and the lower part is penetrated by the moving mechanism. The linear module comprises an electric cylinder and a moving seat driven by the electric cylinder to move linearly, the sensing sheet is arranged on the upper part of the moving seat, and the electric cylinder penetrates the inside of the door stand plate. The supporting mechanism further comprises four air springs and two height limiting columns, the lower ends of the four air springs are seated on the base plate, the upper ends of the four air springs are connected to the four corners of the supporting plate respectively, the two height limiting columns are equal in height and have upper ends connected to the lower surface of the supporting plate, and the two height limiting columns are arranged on both sides of the moving mechanism. The lifting driving element is connected to one side of the door stand plate, and the lifting driving element is a sliding table air cylinder. The pressing mechanism further comprises a pressing frame connected to the lifting driving element and the pressing plate, the pressing plate is arranged at the bottom of the pressing frame, and the pressing plate and the pressing frame form a cuboid structure. ​ S2, calibration: after the linear displacement sensor is powered on, the sensing sheet moves to the mechanical leftmost position, and moves to the mechanical rightmost position at a specified moving speed, and in this process, the displacement value of the sensing sheet is collected by the grating ruler x , the linear displacement sensor can simultaneously obtain two signal output values y 1 、 y 2 , the changes of (1) x , y 1 ) and (2) x , y 2 ) are independently drawn into signal output curves and placed on the same graph, two clamping limit displacement values x a and x b and limit output values y a and y b corresponding to the two clamping limit displacement values are obtained according to the sudden change positions of the signal output values, and then the output clamping is configured, the middle of the linear displacement sensor is at , and the theoretical value of the signal output is ; S3, error detection: after the linear displacement sensor is powered on again, the sensing sheet moves to the mechanical leftmost position, moves to the mechanical rightmost position at a specified moving speed, and collects a group of data every set distance x , y 1 , y 2 ), y 1 is the measured value of the signal output of the first channel when the sensing sheet is at the x position, y 2 is the measured value of the signal output of the second channel when the sensing sheet is at the x position, and then various error calculations are performed; ​ ​ ， ； x 1cal for the first channel under y 1 the calculated value of x back-propagated, x 2cal for the second channel under y 2 the calculated value of x back-propagated, k for the linear displacement sensor ​ conversion factor; ， ； M 1err is the total error under the first channel, M 2err is the total error under the second channel; ； diagnostic error for the linear displacement sensor; The calculation method of the slope error is: fitting all (x, y) as a first straight line to obtain a slope x , ) as a second straight line to obtain a slope g 1 fitting all (x, y) as a second straight line to obtain a slope x , ) as a second straight line to obtain a slope g 2 Then, the slope error is calculated as G 1err and G 2err : ， ； g 1 is a slope of the first straight line, g 2 is a slope of the second straight line, G 1err is a slope error of the first straight line, G 2err is a slope error of the second straight line; According to the first straight line and the second straight line, first find x In the first straight line corresponding displacement fitting value , then find x In the second straight line corresponding displacement fitting value ; The non-linear error is then calculated N 1err and N 2err : ， ； nonlinear error for the first channel, nonlinear error for the second channel.

2. The method of testing a linear displacement sensor according to claim 1, wherein: ​ 3. The method of testing a linear displacement sensor of claim 2, wherein: ​ 4. The method of testing a linear displacement sensor of claim 2, wherein: ​ 5. The method of testing a linear displacement sensor of claim 2, wherein: ​ 6. The method of testing a linear displacement sensor of claim 1, wherein: ​

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