A precision probe guiding mechanism 6-degree-of-freedom data decoupling method

Abstract

The application discloses a kind of 6 degrees of freedom data decoupling methods of precision measuring head guiding mechanism, there is certain gap between fixed part and moving part, it is connected between the two by elastic mechanism, and the coordinate information of measured surface is determined by using sensor sensing elastic deformation amount, when moving in certain fixed direction, the moving part of guiding mechanism is easy to produce linear displacement movement along three-dimensional orthogonal axis and angular displacement movement around three-dimensional orthogonal axis.The application can measure 3 linear displacement amounts and 3 angular displacement amounts, and finally realizes the purpose of improving the measuring precision of measuring head.The method contains differential capacitance sensor and 2 groups of capacitance sensors of orthogonally arranged unequal area electrode plate, can use redundant data to decompose the 6 degrees of freedom of measuring head guiding module along x, y and z axis, and around x, y and z axis with high precision, especially suitable for high-precision guiding module in precision measuring head.

Description

Technical Field

[0001] This invention relates to the field of precision measurement, and in particular to a method for decoupling 6-DOF data of a precision probe guide mechanism. Background Technology

[0002] As a key component of coordinate measuring machines (CMMs), the precision probe's development level directly affects the CMM's measurement accuracy, performance, efficiency, and flexibility. The history of CMM development also shows that only when precision probes provide new sensing principles and higher measurement accuracies can CMMs undergo fundamental changes. In other words, the precision probe is a major factor limiting the accuracy and measurement speed of CMMs, and whether a CMM can meet modern measurement requirements depends on the continuous innovation and development of the precision probe system. Achieving precise measurement of the six degrees of freedom of the guiding mechanism plays a crucial role in improving the probe's measurement accuracy. Summary of the Invention

[0003] The precision probe guiding mechanism consists of a fixed part, a moving part, an elastic mechanism, and sensors. A certain gap exists between the fixed and moving parts, which are connected by the elastic mechanism. The sensors detect the amount of elastic deformation to determine the coordinate information of the measured surface. When moving in a fixed direction, the moving part of the guiding mechanism easily generates linear displacement along a three-dimensional orthogonal axis and angular displacement around that axis. The purpose of this invention is to accurately measure six degrees of freedom and proposes a six-degree-of-freedom data decoupling method for the precision probe guiding mechanism. This method uses a set of differential capacitive sensors and two sets of capacitive sensors of orthogonally arranged unequal-area plates to measure three linear displacements and three angular displacements, ultimately improving the measurement accuracy of the probe.

[0004] The above objectives are achieved through the following technical solutions:

[0005] A guide mechanism based on a 6-DOF data decoupling method for a precision probe guide mechanism includes a vertical connecting plate, a first fixed plate, a second fixed plate, a first upper pressure plate of the first fixed plate, a second upper pressure plate of the first fixed plate, a differential plate, a first upper pressure plate of the first moving plate, a second upper pressure plate of the first moving plate, a second upper pressure plate of the second moving plate, a first moving plate, a second moving plate, a lower pressure plate of the first moving plate, a first lower pressure plate of the second moving plate, a second lower pressure plate of the second moving plate, a first lower pressure plate of the first fixed plate, a second lower pressure plate of the first fixed plate, a second lower pressure plate of the second fixed plate, a first set of springs, a second set of springs, a differential capacitor sensor, a stationary plane of a first unequal surface area positive plate capacitor sensor, a stationary plane of a second unequal surface area positive plate capacitor sensor, a moving plane of a first unequal surface area positive plate capacitor sensor, a moving plane of a second unequal surface area positive plate capacitor sensor, a first fixed plate, a second fixed plate, a third fixed plate, a fourth fixed plate, a first moving plate, a second moving plate, a third moving plate, and a fourth moving plate. The first and second movable plates are connected to the first and second fixed plates via a first set of springs and a second set of springs, enabling the first and second movable plates to move relative to the first and second fixed plates. The force on the probe can come from any direction, so the movement of the first and second movable plates relative to the first and second fixed plates is also in any direction of the six degrees of freedom in space.

[0006] The differential capacitance sensor can measure the linear displacement of the first and second moving plates as a whole along the Z-axis. The 6-DOF movement of the first and second moving plates as a whole can cause a change in the capacitance value of the first unequal area plate capacitance sensor, but it is impossible to decouple the motion of the corresponding degree of freedom solely based on the change in the capacitance value of the first unequal area plate capacitance sensor. The 6-DOF movement of the moving part can cause a change in the capacitance value of the second unequal area plate capacitance sensor, but it is impossible to decouple the motion of the corresponding degree of freedom solely based on the change in the capacitance value of the second unequal area plate capacitance sensor. By combining the differential capacitance sensor, the first unequal area plate capacitance sensor, and the second unequal area plate capacitance sensor, the motion of the corresponding degree of freedom can be decoupled.

[0007] In the first unequal area plate-capacitive sensor and the second unequal area plate-capacitive sensor, the areas of the first fixed plate, the third fixed plate, the first moving plate, the second moving plate, the third moving plate, and the fourth moving plate are equal, both being S1; the areas of the second fixed plate and the fourth fixed plate are equal, both being S2; S1>S2.

[0008] When the first and second moving plates move as a whole along the x-axis by a displacement Δx, the capacitance values ​​of the first fixed plate and the first moving plate of the first unequal area plate-capacitive sensor will decrease; the capacitance values ​​of the third fixed plate and the third moving plate will also decrease; while the capacitance values ​​of the second fixed plate and the second moving plate, and the capacitance values ​​of the fourth fixed plate and the fourth moving plate will not change. Simultaneously, the capacitance values ​​of the first fixed plate and the first moving plate of the second unequal area plate-capacitive sensor will change; the capacitance values ​​of the second fixed plate and the second moving plate will change; the capacitance values ​​of the third fixed plate and the third moving plate will change; and the capacitance values ​​of the fourth fixed plate and the fourth moving plate will change.

[0009] When the first and second moving plates move as a whole along the y-axis by a displacement of Δy, the capacitance values ​​of the first fixed plate and the first moving plate of the first unequal area plate-capacitive sensor will change; the capacitance values ​​of the second fixed plate and the second moving plate will change; the capacitance values ​​of the third fixed plate and the third moving plate will change; and the capacitance values ​​of the fourth fixed plate and the fourth moving plate will change. Simultaneously, the capacitance values ​​of the first fixed plate and the first moving plate of the second unequal area plate-capacitive sensor will decrease; the capacitance values ​​of the third fixed plate and the third moving plate will also decrease; while the capacitance values ​​of the second fixed plate and the second moving plate, and the capacitance values ​​of the fourth fixed plate and the fourth moving plate will not change.

[0010] When the first and second moving plates move as a whole along the z-axis by a displacement Δz, the capacitance value of the differential capacitance sensor will change. The capacitance values ​​of the first fixed plate and the first moving plate of the first unequal area plate capacitance sensor will decrease; the capacitance values ​​of the third fixed plate and the third moving plate will also decrease; while the capacitance values ​​of the second fixed plate and the second moving plate, and the fourth fixed plate and the fourth moving plate will not change. Simultaneously, the capacitance values ​​of the first fixed plate and the first moving plate of the second unequal area plate capacitance sensor will decrease; the capacitance values ​​of the third fixed plate and the third moving plate will also decrease; while the capacitance values ​​of the second fixed plate and the second moving plate, and the fourth fixed plate and the fourth moving plate will not change.

[0011] When the first and second moving plates move as a whole by an angular displacement α around the x-axis, the capacitance values ​​of the first fixed plate and the first moving plate of the first unequal area plate-capacitive sensor will change; the capacitance values ​​of the third fixed plate and the third moving plate will change in the opposite direction; while the capacitance values ​​of the second fixed plate and the second moving plate, and the fourth fixed plate and the fourth moving plate will not change. Simultaneously, the capacitance values ​​of the first fixed plate and the first moving plate of the second unequal area plate-capacitive sensor will decrease; the capacitance values ​​of the third fixed plate and the third moving plate will also decrease; while the capacitance values ​​of the second fixed plate and the second moving plate, and the fourth fixed plate and the fourth moving plate will not change.

[0012] When the first and second moving plates move as a whole by an angular displacement β around the y-axis, the capacitance values ​​of the first fixed plate and the first moving plate of the first unequal area plate-capacitive sensor will decrease; the capacitance values ​​of the third fixed plate and the third moving plate will also decrease; while the capacitance values ​​of the second fixed plate and the second moving plate, and the fourth fixed plate and the fourth moving plate will not change. Simultaneously, the capacitance values ​​of the first fixed plate and the first moving plate of the second unequal area plate-capacitive sensor will change; the capacitance values ​​of the third fixed plate and the third moving plate will change in the opposite direction; while the capacitance values ​​of the second fixed plate and the second moving plate, and the fourth fixed plate and the fourth moving plate will not change.

[0013] When the first and second moving plates move as a whole around the z-axis by an angular displacement ε, the first unequal surface area plate-capacitive sensor and the second unequal surface area plate-capacitive sensor are in the same situation: the capacitance values ​​of the first fixed plate and the first moving plate will decrease, and the capacitance values ​​of the third fixed plate and the third moving plate will also decrease; the capacitance values ​​of the second fixed plate and the second moving plate will change; and the capacitance values ​​of the fourth fixed plate and the fourth moving plate will change in the opposite direction.

[0014] Based on the above-mentioned variation law of displacement and capacitance value, the precise decoupling of the 6-DOF redundant data of the guide mechanism can be achieved.

[0015] This invention has the following characteristics and beneficial effects:

[0016] The method of the present invention includes a differential capacitance sensor and two sets of orthogonally arranged unequal surface capacitance sensors, which can use redundant data to decompose the probe guide module into six degrees of freedom along the x, y, and z axes, as well as around the x, y, and z axes with high precision.

[0017] The device of this invention has a wide range of applications, and is especially suitable for high-precision guidance modules in precision probes. Attached Figure Description

[0018] Figure 1 This is a structural diagram of the precision probe guide mechanism.

[0019] Figure 2 This is a partial structural diagram of the fixed and moving parts of the guiding mechanism.

[0020] Figure 3 This is a schematic diagram of the measurement principle of a differential capacitance sensor.

[0021] Figure 4 This is a schematic diagram of the measurement principle of the first unequal surface plate capacitive sensor.

[0022] Figure 5 This is a schematic diagram of the measurement principle of the second unequal surface plate capacitive sensor.

[0023] In the diagram, the markings are: 1-Vertical connecting plate; 2-1-First fixed plate; 2-2-Second fixed plate; 3-1-First fixed plate first upper pressure plate; 3-2-First fixed plate second upper pressure plate; 4-Differential plate; 5-1-First moving plate first upper pressure plate; 5-2-First moving plate second upper pressure plate; 6-Second moving plate upper pressure plate; 7-1-First moving plate; 7-2-Second moving plate; 8-First moving plate lower pressure plate; 9-1-Second moving plate first lower pressure plate; 9-2-Second moving plate second lower pressure plate; 10-1-First fixed plate first lower pressure plate; 10-2-First fixed plate second lower pressure plate; 11-1- 11-2-Second fixed plate, first lower pressure plate; 12-First set of springs; 13-Second set of springs; 14-Differential capacitor sensor; 15-First unequal surface area positive plate capacitor sensor static plane; 16-Second unequal surface area positive plate capacitor sensor static plane; 17-First unequal surface area positive plate capacitor sensor moving plane; 18-Second unequal surface area positive plate capacitor sensor moving plane; 19-First fixed plate; 20-Second fixed plate; 21-Third fixed plate; 22-Fourth fixed plate; 23-First moving plate; 24-Second moving plate; 25-Third moving plate; 26-Fourth moving plate. Detailed Implementation

[0024] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. However, this should not be construed as limiting the scope of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0025] like Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5As shown, the guiding mechanism upon which a 6-DOF data decoupling method for a precision probe guide mechanism is based includes a vertical connecting plate 1, a first fixed plate 2-1, a second fixed plate 2-2, a first upper pressure plate 3-1 of the first fixed plate, a second upper pressure plate 3-2 of the first fixed plate, a differential plate 4, a first upper pressure plate 5-1 of the first moving plate, a second upper pressure plate 5-2 of the first moving plate, a second upper pressure plate 6 of the second moving plate, a first moving plate 7-1 of the first moving plate, a second moving plate 7-2 of the second moving plate, a lower pressure plate 8 of the first moving plate, a first lower pressure plate 9-1 of the second moving plate, a second lower pressure plate 9-2 of the second moving plate, a first lower pressure plate 10-1 of the first fixed plate, and a first fixed plate. Second lower pressure plate 10-2, second fixed plate, first lower pressure plate 11-1, second fixed plate, second lower pressure plate 11-2, first set of springs 12, second set of springs 13, differential capacitor sensor 14, first unequal surface positive plate capacitor sensor static plane 15, second unequal surface positive plate capacitor sensor static plane 16, first unequal surface positive plate capacitor sensor moving plane 17, second unequal surface positive plate capacitor sensor moving plane 18, first fixed plate 19, second fixed plate 20, third fixed plate 21, fourth fixed plate 22, first moving plate 23, second moving plate 24, third moving plate 25, fourth moving plate 26. The first moving plate 7-1 and the second moving plate 7-2 are connected to the first fixed plate 2-1 and the second fixed plate 2-2 as a whole through the first set of springs 12 and the second set of springs 13, so that the first moving plate 7-1 and the second moving plate 7-2 as a whole can move relative to the first fixed plate 2-1 and the second fixed plate 2-2 as a whole; the first unequal surface area positive plate capacitive sensor static plane 15 and the first unequal surface area positive plate capacitive sensor moving plane 17 form the first unequal surface area positive plate capacitive sensor; the second unequal surface area positive plate capacitive sensor static plane 16 and the second unequal surface area positive plate capacitive sensor moving plane 18 form the second unequal surface area positive plate capacitive sensor; the force on the probe can come from any direction, so the movement of the first moving plate 7-1 and the second moving plate 7-2 as a whole relative to the first fixed plate 2-1 and the second fixed plate 2-2 as a whole is also any direction in the six degrees of freedom of space.

[0026] like Figure 3As shown, the differential capacitance sensor 14 can measure the linear displacement of the first moving plate 7-1 and the second moving plate 7-2 as a whole along the Z-axis. The 6-DOF movement of the first moving plate 7-1 and the second moving plate 7-2 as a whole can cause a change in the capacitance value of the first unequal area plate capacitance sensor, but it is impossible to decouple the motion of the corresponding degree of freedom solely based on the change in the capacitance value of the first unequal area plate capacitance sensor. The 6-DOF movement of the first moving plate 7-1 and the second moving plate 7-2 as a whole can cause a change in the capacitance value of the second unequal area plate capacitance sensor, but it is impossible to decouple the motion of the corresponding degree of freedom solely based on the change in the capacitance value of the second unequal area plate capacitance sensor. By combining the differential capacitance sensor 14, the first unequal area plate capacitance sensor, and the second unequal area plate capacitance sensor, the motion of the corresponding degree of freedom can be decoupled.

[0027] like Figure 4 and Figure 5 As shown, in the first unequal area plate-capacitive sensor and the second unequal area plate-capacitive sensor, the areas of the first fixed plate 19, the third fixed plate 21, the first moving plate 23, the second moving plate 24, the third moving plate 25 and the fourth moving plate 26 are equal, both being S1; the areas of the second fixed plate 20 and the fourth fixed plate 22 are equal, both being S2; S1>S2.

[0028] When the first moving plate 7-1 and the second moving plate 7-2 move as a whole along the x-axis by a displacement Δx, the capacitance values ​​of the first fixed plate 19 and the first moving plate 23 of the first unequal area plate-capacitive sensor will decrease; the capacitance values ​​of the third fixed plate 32 and the third moving plate 25 will also decrease; while the capacitance values ​​of the second fixed plate 20 and the second moving plate 24, and the capacitance values ​​of the fourth fixed plate 22 and the fourth moving plate 26 will not change. Simultaneously, the capacitance values ​​of the first fixed plate 19 and the first moving plate of the second unequal area plate-capacitive sensor will change by 23; the capacitance values ​​of the second fixed plate 20 and the second moving plate 24 will change; the capacitance values ​​of the third fixed plate 21 and the third moving plate 25 will change; and the capacitance values ​​of the fourth fixed plate 22 and the fourth moving plate 26 will change.

[0029] When the first moving plate 7-1 and the second moving plate 7-2 move as a whole along the y-axis by a displacement of Δy, the capacitance values ​​of the first fixed plate 19 and the first moving plate 23 of the first unequal area plate-mounted capacitance sensor will change; the capacitance values ​​of the second fixed plate 20 and the second moving plate 24 will change; the capacitance values ​​of the third fixed plate 21 and the third moving plate 25 will change; and the capacitance values ​​of the fourth fixed plate 22 and the fourth moving plate 26 will change. Simultaneously, the capacitance values ​​of the first fixed plate 19 and the first moving plate 23 of the second unequal area plate-mounted capacitance sensor will decrease; the capacitance values ​​of the third fixed plate 21 and the third moving plate 25 will also decrease; while the capacitance values ​​of the second fixed plate 20 and the second moving plate 24, and the capacitance values ​​of the fourth fixed plate 22 and the fourth moving plate 26 will not change.

[0030] When the first moving plate 7-1 and the second moving plate 7-2 move as a whole along the z-axis by a displacement of Δz, the capacitance value of the differential capacitance sensor 14 will change; the capacitance values ​​of the first fixed plate 19 and the first moving plate 23 of the first unequal area plate capacitance sensor will decrease; the capacitance values ​​of the third fixed plate 21 and the third moving plate 25 will also decrease; while the capacitance values ​​of the second fixed plate 20 and the second moving plate 24, and the fourth fixed plate 22 and the fourth moving plate 26 will not change. Simultaneously, the capacitance values ​​of the first fixed plate 19 and the first moving plate 23 of the second unequal area plate capacitance sensor will decrease; the capacitance values ​​of the third fixed plate 21 and the third moving plate 25 will also decrease; while the capacitance values ​​of the second fixed plate 20 and the second moving plate 24, and the fourth fixed plate 22 and the fourth moving plate 26 will not change.

[0031] When the first moving plate 7-1 and the second moving plate 7-2 move by an angular displacement α around the x-axis, the capacitance values ​​of the first fixed plate 19 and the first moving plate 23 of the first unequal area plate-mounted capacitance sensor will change; the capacitance values ​​of the third fixed plate 21 and the third moving plate 25 will change in the opposite direction; while the capacitance values ​​of the second fixed plate 20 and the second moving plate 24, and the fourth fixed plate 22 and the fourth moving plate 26 will not change. Simultaneously, the capacitance values ​​of the first fixed plate 19 and the first moving plate 23 of the second unequal area plate-mounted capacitance sensor will decrease; the capacitance values ​​of the third fixed plate 21 and the third moving plate 25 will also decrease; while the capacitance values ​​of the second fixed plate 20 and the second moving plate 24, and the fourth fixed plate 22 and the fourth moving plate 26 will not change.

[0032] When the first moving plate 7-1 and the second moving plate 7-2 move by an angular displacement β around the y-axis, the capacitance values ​​of the first fixed plate 19 and the first moving plate 23 of the first unequal area plate-mounted capacitance sensor will decrease; the capacitance values ​​of the third fixed plate 21 and the third moving plate 25 will also decrease; while the capacitance values ​​of the second fixed plate 20 and the second moving plate 24, and the capacitance values ​​of the fourth fixed plate 22 and the fourth moving plate 26 will not change. Simultaneously, the capacitance values ​​of the first fixed plate 19 and the first moving plate 23 of the second unequal area plate-mounted capacitance sensor will change; the capacitance values ​​of the third fixed plate 21 and the third moving plate 25 will change in the opposite direction; while the capacitance values ​​of the second fixed plate 20 and the second moving plate 24, and the capacitance values ​​of the fourth fixed plate 22 and the fourth moving plate 26 will not change.

[0033] When the first moving plate 7-1 and the second moving plate 7-2 move as a whole around the z-axis by an angular displacement ε, the first unequal surface area plate capacitive sensor and the second unequal surface area plate capacitive sensor are in the same situation: the capacitance values ​​of the first fixed plate 19 and the first moving plate 23 will decrease, and the capacitance values ​​of the third fixed plate 21 and the third moving plate 25 will also decrease; the capacitance values ​​of the second fixed plate 20 and the second moving plate 24 will change; and the capacitance values ​​of the fourth fixed plate 22 and the fourth moving plate 26 will change in the opposite direction.

[0034] Based on the above-mentioned variation law of displacement and capacitance value, the precise decoupling of the 6-DOF redundant data of the guide mechanism can be achieved.

[0035] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention, and various modifications to these embodiments will be readily apparent to those skilled in the art. The general principles defined herein may be embodied in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown in this method, but is required to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A 6-DOF data decoupling method for a precision probe guide mechanism, wherein the guide mechanism implementing the method includes a fixed part and a moving part; the fixed part includes an L-shaped fixed plate, an L-shaped fixed plate first upper pressure plate, an L-shaped fixed plate second upper pressure plate, an L-shaped fixed plate first lower pressure plate, an L-shaped fixed plate second lower pressure plate, a differential plate, a differential capacitance sensor, a first unequal surface area positive plate capacitance sensor static plane, and a second unequal surface area positive plate capacitance sensor static plane; the moving part includes an L-shaped moving plate, an L-shaped moving plate first upper pressure plate, an L-shaped moving plate second upper pressure plate, an L-shaped moving plate first lower pressure plate, an L-shaped moving plate second lower pressure plate, a first set of springs, a second set of springs, a first unequal surface area positive plate capacitance sensor moving plane, and a second unequal surface area positive plate capacitance sensor moving plane; the fixed part and the moving part are connected by the first set of springs and the second set of springs, enabling the moving part to move relative to the fixed part; the force on the probe stylus can come from any direction, therefore the movement of the moving part relative to the fixed part is also any direction in the 6-DOF spatial direction; characterized in that A differential capacitance sensor can measure the linear displacement of the moving part along the Z-axis. The 6-DOF movement of the moving part can cause a change in the capacitance value of the first unequal-area plate capacitor sensor, but the motion of the corresponding degree of freedom cannot be decoupled solely from the change in the capacitance value of the first unequal-area plate capacitor sensor. The 6-DOF movement of the moving part can cause a change in the capacitance value of the second unequal-area plate capacitor sensor, but the motion of the corresponding degree of freedom cannot be decoupled solely from the change in the capacitance value of the second unequal-area plate capacitor sensor. By combining the differential capacitance sensor, the first unequal-area plate capacitor sensor, and the second unequal-area plate capacitor sensor, the motion of the corresponding degree of freedom can be decoupled. In the first unequal area plate-capacitive sensor and the second unequal area plate-capacitive sensor, the areas of the first fixed plate, the third fixed plate, the first moving plate, the second moving plate, the third moving plate, and the fourth moving plate are equal, both being S1; the areas of the second fixed plate and the fourth fixed plate are equal, both being S2; S1>S2. When the moving part moves Δx along the x-axis, the capacitance values ​​of the first fixed plate and the first moving plate of the first unequal area plate-capacitive sensor decrease; the capacitance values ​​of the third fixed plate and the third moving plate also decrease; while the capacitance values ​​of the second fixed plate and the second moving plate, and the capacitance values ​​of the fourth fixed plate and the fourth moving plate do not change. Simultaneously, the capacitance values ​​of the first fixed plate and the first moving plate of the second unequal area plate-capacitive sensor change; the capacitance values ​​of the second fixed plate and the second moving plate change; the capacitance values ​​of the third fixed plate and the third moving plate change; and the capacitance values ​​of the fourth fixed plate and the fourth moving plate change. When the moving part moves Δy along the y-axis, the capacitance values ​​of the first fixed plate and the first moving plate of the first unequal surface area plate-capacitive sensor will change; the capacitance values ​​of the second fixed plate and the second moving plate will change; the capacitance values ​​of the third fixed plate and the third moving plate will change; the capacitance values ​​of the fourth fixed plate and the fourth moving plate will change; simultaneously, the capacitance values ​​of the first fixed plate and the first moving plate of the second unequal surface area plate-capacitive sensor will decrease; the capacitance values ​​of the third fixed plate and the third moving plate will also decrease; while the capacitance values ​​of the second fixed plate and the second moving plate, and the capacitance values ​​of the fourth fixed plate and the fourth moving plate will not change. When the moving part moves Δz along the z-axis, the capacitance value of the differential capacitance sensor changes; the capacitance values ​​of the first fixed plate and the first moving plate of the first unequal surface area plate capacitance sensor decrease; the capacitance values ​​of the third fixed plate and the third moving plate also decrease; while the capacitance values ​​of the second fixed plate and the second moving plate, and the fourth fixed plate and the fourth moving plate do not change; simultaneously, the capacitance values ​​of the first fixed plate and the first moving plate of the second unequal surface area plate capacitance sensor decrease; the capacitance values ​​of the third fixed plate and the third moving plate also decrease; while the capacitance values ​​of the second fixed plate and the second moving plate, and the fourth fixed plate and the fourth moving plate do not change. When the moving part moves by an angular displacement α around the x-axis, the capacitance values ​​of the first fixed plate and the first moving plate of the first unequal area plate-capacitive sensor will change; the capacitance values ​​of the third fixed plate and the third moving plate will change in the opposite direction; while the capacitance values ​​of the second fixed plate and the second moving plate, and the capacitance values ​​of the fourth fixed plate and the fourth moving plate will not change; at the same time, the capacitance values ​​of the first fixed plate and the first moving plate of the second unequal area plate-capacitive sensor will decrease; the capacitance values ​​of the third fixed plate and the third moving plate will also decrease; while the capacitance values ​​of the second fixed plate and the second moving plate, and the capacitance values ​​of the fourth fixed plate and the fourth moving plate will not change. When the moving part moves by an angular displacement β around the y-axis, the capacitance values ​​of the first fixed plate and the first moving plate of the first unequal surface area plate-capacitive sensor decrease; the capacitance values ​​of the third fixed plate and the third moving plate also decrease; while the capacitance values ​​of the second fixed plate and the second moving plate, and the capacitance values ​​of the fourth fixed plate and the fourth moving plate do not change. Simultaneously, the capacitance values ​​of the first fixed plate and the first moving plate of the second unequal surface area plate-capacitive sensor change; the capacitance values ​​of the third fixed plate and the third moving plate change in the opposite direction; while the capacitance values ​​of the second fixed plate and the second moving plate, and the capacitance values ​​of the fourth fixed plate and the fourth moving plate do not change. When the moving part moves by an angular displacement ε around the z-axis, the situation is the same for the first unequal surface area plate-capacitive sensor and the second unequal surface area plate-capacitive sensor: the capacitance values ​​of the first fixed plate and the first moving plate will decrease, and the capacitance values ​​of the third fixed plate and the third moving plate will also decrease; the capacitance values ​​of the second fixed plate and the second moving plate will change; and the capacitance values ​​of the fourth fixed plate and the fourth moving plate will change in the opposite direction.

2. The method of claim 1, wherein, Based on the variation law of displacement and capacitance value, the precise decoupling of the 6-DOF redundant data of the guide mechanism is achieved.

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