A device and calculation method for detecting the posture of a parallel robot platform

Abstract

The present invention discloses a device and calculation method for detecting the posture of a parallel robot platform, the device includes a central ballbar, an offset ballbar, a dynamic platform two-dimensional inclination sensor, and a static platform two-dimensional inclination sensor; the upper and lower ends of the central ballbar are respectively fixedly installed with the center points of the dynamic platform and the static platform of the parallel robot; the dynamic platform two-dimensional inclination sensor is fixedly installed on the lower surface of the dynamic platform of the parallel robot; the static platform two-dimensional inclination sensor is fixedly installed on the upper surface of the static platform of the parallel robot; the offset ballbar has the same structure as the central ballbar and is arranged in parallel, and its installation position deviates from the center points of the static platform and the dynamic platform of the parallel robot. The full motion space posture measurement of the parallel robot is realized by the combined measurement method of the two-dimensional inclination sensor and the ballbar, with high accuracy and simple system structure, and the accurate detection of the initial posture of the parallel robot is realized by using dual two-dimensional inclination sensors.

Description

Technical Field

[0001] The invention belongs to the technical field of robot posture measurement, and in particular relates to a device and a calculation method for detecting the posture of a parallel robot platform. Background Art

[0002] Robots and high-end CNC machine tools are two key technical equipment for development. Robot research and development, manufacturing, and application are important indicators of a country's scientific and technological innovation and high-end manufacturing level. With the rapid development of robot technology, the requirements for the precision performance of robots are getting higher and higher. Compared with serial industrial robots, parallel robots have better structural rigidity, higher load capacity, and more outstanding precision performance. They are increasingly used in intelligent flexible assembly in the field of high-end manufacturing. Parallel robots usually include a dynamic platform, a static platform, and a connecting rod mechanism. The connecting rod mechanism is generally divided into three types: hydraulic, pneumatic, and electric, among which the electric method is more widely used.

[0003] At present, parallel robots belong to the semi-closed loop control form, mainly because the current measurement technology cannot realize the posture measurement of the full motion space of the parallel robot. There are some methods that use visual measurement equipment to realize posture measurement, but visual measurement equipment is easily affected by ambient light and cannot cover the entire motion space of the parallel robot; there are also methods that realize posture measurement through multiple wire sensors. At present, the accuracy of wire sensors is not only affected by the accuracy of their encoders, but the error of wire sensors will also increase with the increase of their measurement length. There are also methods that realize the posture measurement of parallel robots through multiple electronic rulers, but since such systems use multiple electronic rulers, their assembly errors will affect the measurement results. Therefore, how to realize the posture measurement of the full motion space of the parallel robot is one of the key issues that need to be solved urgently.

[0004] After completing the corresponding task, the parallel robot needs to return to the zero position, and the zero position is usually calibrated after the parallel robot is manufactured. At present, the parallel robot is mainly reset to zero by controlling the length of the support rod. The zero position of the parallel robot, whether it is installed with an absolute encoder or an incremental encoder, requires the electric cylinder to be controlled to the limit position for the first configuration, and the current position is recorded as the zero position of the electric cylinder. The corresponding platform position is the zero position of the parallel robot. When the electric cylinder reaches the limit position, it is often a hard collision, which has a greater impact on the life of the drive mechanism of the parallel robot.

[0005] Therefore, it is urgent to propose a detection device and calculation method for the posture of a parallel robot platform, which can realize the zero-position configuration of the parallel robot and high-precision posture measurement in the entire motion space. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a device and a calculation method for detecting the posture of a parallel robot platform in view of the above-mentioned deficiencies in the prior art. The device has a compact structure and high measurement accuracy and can realize the posture measurement of the entire motion space of the parallel robot.

[0007] In order to achieve the above technical objectives, the technical solution adopted by the present invention is:

[0008] A device for detecting the position and posture of a parallel robot platform, comprising a center ballbar, an offset ballbar, a dynamic platform two-dimensional inclination sensor, and a static platform two-dimensional inclination sensor;

[0009] The upper and lower ends of the center ballbar are fixedly installed on the center points of the moving platform and the static platform of the parallel robot respectively;

[0010] The moving platform two-dimensional inclination sensor is fixedly installed on the lower surface of the moving platform of the parallel robot;

[0011] The static platform two-dimensional inclination sensor is fixedly installed on the upper surface of the static platform of the parallel robot;

[0012] The offset ballbar has the same structure as the central ballbar and is arranged in parallel. Its installation position deviates from the center point of the static platform and the dynamic platform of the parallel robot.

[0013] To optimize the above technical solutions, the specific measures taken also include:

[0014] The central ballbar comprises a static platform magnetic base, a dynamic platform magnetic base, a ballbar and a ballbar two-dimensional inclination sensor;

[0015] The static platform magnetic base is fixedly connected to the static platform of the parallel robot, and the dynamic platform magnetic base is fixedly connected to the dynamic platform of the parallel robot;

[0016] The two ends of the ballbar are respectively fixed in the magnetic base of the static platform and the magnetic base of the dynamic platform, and the two-dimensional inclination sensor of the ballbar is fixedly installed on the ballbar.

[0017] The method for calculating the posture of a parallel robot platform includes:

[0018] When the parallel robot is in the initial position, the directions of the X and Y axes of the two-dimensional inclination sensor of the moving platform are kept consistent with the coordinate system of the moving platform of the parallel robot, and the directions of the X and Y axes of the two-dimensional inclination sensor of the static platform are kept consistent with the coordinate system of the static platform of the parallel robot;

[0019] The axial inclination angles output by the two-dimensional inclination sensor of the moving platform and the two-dimensional inclination sensor of the static platform are converted into Euler angles through data conversion. Combined with the detection points of the center ballbar and the offset ballbar, the relative posture detection of the moving platform and the static platform is realized.

[0020] The specific steps of converting the output inclination angles of the above-mentioned two-dimensional inclination sensor of the moving platform and the two-dimensional inclination sensor of the static platform into Euler angles are as follows:

[0021] Step 1: The two values ​​β and γ output by the two-dimensional inclinometer are the angles between its X-axis and Y-axis and the horizontal plane. The XOY plane of the reference coordinate system is parallel to the horizontal plane. Therefore, the angle output by the two-dimensional inclinometer in the X-axis direction is the rotation angle around the Y-axis.

[0022] Step 2: Since the angle output in the Y-axis direction is not equal to the rotation angle around the X-axis, the rotation angle of the two-dimensional inclinometer around the Y-axis in the spatial coordinates is derived. The relationship between the rotation angle ω around the X-axis and the angles β and γ of the X-axis and Y-axis output by the two-dimensional inclination sensor;

[0023] Step 3: When the reading of the static platform 2D inclination sensor is zero:

[0024] Establish a reference coordinate system {O}, where the directions of the X and Y axes are the same as those of the inclinometer itself. According to the right-hand rule, the Z axis is vertically upward, and the origin of the coordinate system is located at the midpoint of the upper surface of the static platform.

[0025] Establish a static platform coordinate system {B}. When the parallel robot is placed in an absolutely horizontal position, the static platform coordinate system {B} coincides with the reference coordinate system {O}.

[0026] Establish the moving platform coordinate system {M}. When the parallel robot is at the absolute zero position, the moving platform coordinate system {M} is the static platform coordinate system {B} translated along the Z axis by a distance L, where L is the vertical distance between the moving and static platforms.

[0027] According to the relationship obtained in step 2, the rotation angles α1, β1, α2, and β2 of the moving and static platforms around the X-axis and Y-axis can be calculated from the readings of the two-dimensional inclination sensor of the static platform and the two-dimensional inclination sensor of the dynamic platform. From this, the rotation matrix of the moving and static platform coordinate systems {M} and {B} relative to the reference coordinate system {O} can be calculated. So we can get the rotation matrix between the moving and static platform coordinate systems

[0028]

[0029] Rotate according to the ZYX Euler angles in sequence, and the matrix is ​​described as:

[0030]

[0031] The Euler angles can be solved as follows:

[0032]

[0033] Step 4: According to step 2 and step 3, combined with the detection points of the center ballbar and the offset ballbar, the posture data of the moving platform of the parallel robot in the static platform coordinate system is calculated.

[0034] The derivation process of the relationship described in step 2 above is:

[0035] In spatial coordinates, assume that the straight line OE is perpendicular to the plane OAC and the plane BDE, so OE⊥BE, OE⊥BF, extend ED to F so that the straight line BF is parallel to the straight line AO, then ∠BFD=β, and BF⊥OB, therefore, BF⊥plane OBE, then BF⊥BE, so ∠DBE=∠BFD=β;

[0036] From the triangular relationship, we can know that:

[0037]

[0038] The relationship between the output angle of the two-dimensional tilt sensor and the corresponding rotation angle can be obtained:

[0039]

[0040] That is, the rotation angle of the inclinometer around the Y axis in spatial coordinates The relationship between the rotation angle ω around the X-axis and the angles β and γ of the X-axis and Y-axis output by the inclinometer is shown in formula (1.2).

[0041] Step 4 above includes:

[0042] Step S1: establishing a coordinate system {I} of the ballbar's two-dimensional inclination sensor, with its origin located at the center of the ballbar. When the parallel robot is at the initial zero position, the coordinate system {I} is the static platform coordinate system {B} translated by L1 along the positive direction of the Z axis, where L1 is the distance between the ballbar's two-dimensional inclination sensor mounted on the ballbar and the static platform.

[0043] Step S2: after the parallel robot moves, the coordinate system {O1} is the coordinate system {O} rotated around the Y axis and the X axis by angles β and α, respectively. The angles β and α are calculated by substituting the output angles of the two-dimensional inclination sensor of the ballbar into the relationship derived in step 2;

[0044] Coordinate system {I} is coordinate system {O1} translated by L1 along the positive direction of Z axis, OP is the distance between the midpoints of the upper and lower platforms, recorded as L2. The value of L2 is known and can be read out by ballbar.

[0045] Calculate the rotation matrix based on the transformation relationship between coordinate system {O} and coordinate system {O1}

[0046]

[0047] Step S3: The coordinates of point P in the coordinate system {O1} are , known and , find the position coordinates of point P in the coordinate system {O}:

[0048]

[0049] It is known that the transformation relationship between the coordinate system {O} and the coordinate system {B} is Therefore, the position coordinates of point P in the coordinate system {B} can be calculated:

[0050]

[0051] Based on the posture information obtained by the Euler angle solution formula and the position information obtained by formula (1.8), the posture information of the moving platform coordinate system {M} relative to the static platform coordinate system {B} is obtained.

[0052] The above step 4 also includes:

[0053] When the parallel robot rotates horizontally, the detection point position P1 is detected by the offset ballbar, and the detection point position P2 is detected by the center ballbar. The line connecting the two points P1 and P2 is projected into the coordinate system {O}. The angle between the line and the X-axis of the coordinate system {O} is the horizontal plane rotation angle of the parallel robot's dynamic platform.

[0054] The present invention has the following beneficial effects:

[0055] (1) The combined measurement method of the two-dimensional inclination sensor and the ballbar is used to measure the full motion space posture of the parallel robot. The measurement has high accuracy and a simple system structure. Compared with the wire sensor, the ballbar has higher measurement accuracy. At the same time, the ballbar has a rigid structure, and its measurement error does not increase with the increase of the measurement distance.

[0056] (2) The dual two-dimensional inclination sensors are used to accurately detect the initial posture of the parallel robot. Compared with the technical solution of installing the inclination sensor only on the moving platform, the posture measured by the present invention is not based on the static platform coordinate system and is not affected by the installation conditions of the parallel robot. Therefore, the relative posture obtained by the present invention more accurately reflects the posture relationship between the moving platform and the static platform. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 is an overall schematic diagram of the device of the present invention installed on a parallel robot;

[0058] Figure 2 is a schematic diagram of the installation of the two-dimensional inclination sensor of the present invention on a ballbar;

[0059] Figure 3 Schematic diagram of converting the output angle of the inclinometer of the present invention into Euler angles;

[0060] Figure 4 It is a schematic diagram of position measurement of the parallel robot of the present invention. DETAILED DESCRIPTION

[0061] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0062] Although the steps in the present invention are arranged with numbers, they are not used to limit the order of the steps. Unless the order of the steps is clearly stated or the execution of a certain step requires other steps as a basis, the relative order of the steps can be adjusted. It is understood that the term "and / or" used in this article involves and covers any and all possible combinations of one or more of the associated listed items.

[0063] See also Figure 1 As shown, a parallel robot platform posture detection device of the present invention is installed inside a parallel robot 3, and mainly comprises a center ball bar 1, an offset ball bar 2, a moving platform two-dimensional inclination sensor 4, and a static platform two-dimensional inclination sensor 5;

[0064] The upper and lower ends of the central ballbar 1 are fixedly mounted to the center points of the moving platform and the static platform of the parallel robot 3 respectively;

[0065] The moving platform two-dimensional inclination sensor 4 is fixedly mounted on the lower surface of the moving platform of the parallel robot 3 by screws;

[0066] The static platform two-dimensional inclination sensor 5 is fixedly mounted on the upper surface of the static platform of the parallel robot 3 by screws.

[0067] The moving platform two-dimensional inclination sensor 4 and the stationary platform two-dimensional inclination sensor 5 only measure the angles of two axes, and can realize the detection of the relative posture of the two.

[0068] When the parallel robot 3 is in the initial position, the directions of the X and Y axes of the moving platform two-dimensional inclination sensor 4 are kept consistent with the moving platform coordinate system of the parallel robot 3, and the directions of the X and Y axes of the static platform two-dimensional inclination sensor 5 are kept consistent with the static platform coordinate system of the parallel robot 3. Since the moving platform two-dimensional inclination sensor 4 and the static platform two-dimensional inclination sensor 5 are fixedly mounted on the moving platform and static platform surfaces of the parallel robot 3, the moving platform two-dimensional inclination sensor 4 and the static platform two-dimensional inclination sensor 5 are only two axial angles, which can be converted into Euler angles through data conversion, thereby realizing the detection of the relative posture of the two.

[0069] See also Figure 3 As shown, the specific steps of converting the inclination angle output by the moving platform two-dimensional inclination sensor 4 and the static platform two-dimensional inclination sensor 5 into Euler angles are as follows:

[0070] Step 1: The two values ​​β and γ output by the two-dimensional inclinometer are the angles between its X-axis and Y-axis and the horizontal plane. The XOY plane of the reference coordinate system is parallel to the horizontal plane. Therefore, the angle output by the two-dimensional inclinometer in the X-axis direction is the rotation angle around the Y-axis.

[0071] Step 2: Since the angle output in the Y-axis direction is not equal to the rotation angle around the X-axis, the derivation process of angle calculation is as follows:

[0072] Combination Figure 3 :Line OE is perpendicular to plane OAC and plane BDE, so OE⊥BE, OE⊥BF. Extend ED to F so that line BF is parallel to line AO, then ∠BFD=β, and BF⊥OB. Therefore, BF⊥plane OBE, then BF⊥BE. So ∠DBE=∠BFD=β.

[0073] From the triangular relationship, we can know that:

[0074]

[0075] In this way, the relationship between the output angle of the two-dimensional tilt sensor and the corresponding rotation angle can be obtained:

[0076]

[0077] That is, the rotation angle of the inclinometer around the Y axis in spatial coordinates The relationship between the rotation angle ω around the X-axis and the angles β and γ of the X-axis and Y-axis output by the inclinometer is shown in formula (1.2).

[0078] Step 3: When the reading of the static platform two-dimensional inclination sensor 5 is zero, establish a reference coordinate system {O}. The directions of the X and Y axes are the same as those of the inclinometer itself. According to the right-hand rule, the Z axis is vertically upward, and the origin of the coordinates is located at the midpoint of the upper surface of the static platform. Establish a static platform coordinate system {B}. When the parallel robot is placed in an absolute horizontal position, the static platform coordinate system {B} coincides with the reference coordinate system {O}. Establish a dynamic platform coordinate system {M}. When the parallel robot is in an absolute zero position, the dynamic platform coordinate system {M} is the static platform coordinate system {B} translated along the Z axis by a distance L, where L is the vertical distance between the dynamic and static platforms. According to formula (1.2), the rotation angles α1, β1, α2, and β2 of the dynamic and static platforms around the X and Y axes can be calculated from the readings of the static platform two-dimensional inclination sensor 5 and the dynamic platform two-dimensional inclination sensor 4. From this, the rotation matrix of the dynamic and static platform coordinate systems {M} and {B} relative to the reference coordinate system {O} can be calculated. So we can get the rotation matrix between the moving and static platform coordinate systems

[0079]

[0080] Rotate according to the ZYX Euler angles in sequence, and the matrix is ​​described as:

[0081]

[0082] The Euler angles can be solved as follows:

[0083]

[0084] Step 4: According to the above steps, the posture data of the moving platform of the parallel robot 3 in the static platform coordinate system can be obtained.

[0085] See also Figure 2 As shown, the center ballbar 1 and the offset ballbar 2 have the same structure, both comprising a static platform magnetic base, a dynamic platform magnetic base, a ballbar and a ballbar two-dimensional inclination sensor.

[0086] The actual structure is introduced by taking the central ballbar 1 as an example. The central ballbar 1 mainly comprises a static platform magnetic base 103 , a dynamic platform magnetic base 101 , a ballbar 102 and a ballbar two-dimensional inclination sensor 104 .

[0087] The static platform magnetic base 103 is fixedly connected to the static platform of the parallel robot 3, and the dynamic platform magnetic base 101 is fixedly connected to the dynamic platform of the parallel robot 3; the static platform magnetic base and the dynamic platform magnetic base are respectively installed at the center of the upper plane of the static platform and the center of the lower plane of the dynamic platform, and the centers of the two magnetic bases are spherical grooves; the two ends of the ballbar 102 are respectively fixed in the static platform magnetic base 103 and the dynamic platform magnetic base 101, and the ballbar two-dimensional inclination sensor 104 is fixed on the ballbar 102. The ballbar is a retractable linear displacement sensor, with a precision ball at each end, which is adsorbed in the spherical grooves of the static platform magnetic base and the dynamic platform magnetic base. The center point position of the robot is measured according to the above device.

[0088] When the moving platform moves, the ballbar will be pulled to extend and retract, thereby measuring the distance between the center of the spherical groove of the magnetic base of the static platform and the magnetic base of the dynamic platform. The two-dimensional inclination sensor of the ballbar is fixed together with the mounting base, and the mounting base is fixedly mounted on the ballbar. The two-dimensional inclination sensor of the ballbar can measure the angle between the X-axis and the Y-axis of the ballbar relative to the static platform coordinate system. According to the definition of three-dimensional polar coordinates, the position expression of the precision ball on the upper end of the ballbar in the static coordinate system can be calculated. Compared with the wire sensor, the ballbar has higher measurement accuracy. At the same time, the ballbar has a rigid structure, and its measurement error will not increase with the increase of the measurement distance.

[0089] When the conversion relationship between the static platform magnetic base and the dynamic platform magnetic base and the static platform and dynamic platform is known, the position expression of the dynamic platform coordinate system in the static platform coordinate system can be calculated. The specific steps are as follows:

[0090] Step S1: See Figure 4 As shown, coordinate system {I} is the coordinate system of the ballbar two-dimensional inclination sensor 104, and the coordinate origin is located at the center of the ballbar 102. When the parallel robot 3 is at the initial zero position, coordinate system {I} is the static platform coordinate system {B} translated by L1 along the positive direction of the Z axis, and L1 is the distance between the ballbar two-dimensional inclination sensor 104 installed on the ballbar 102 and the static platform.

[0091] Step S2: After the parallel robot 3 moves, the coordinate system {O1} is the coordinate system {O} rotated around the Y-axis and the X-axis by angles β and α, respectively. The angles β and α can be calculated by substituting the output angles of the ballbar two-dimensional inclination sensor 104 into formula (1.2).

[0092] Coordinate system {I} is coordinate system {O1} translated by L1 along the positive direction of the Z axis. OP is the distance between the midpoints of the upper and lower platforms, recorded as L2. The value of L2 is known and can be read out by the ballbar 102. According to the transformation relationship between coordinate system {O} and coordinate system {O1}, the rotation matrix can be obtained.

[0093]

[0094] Step S3: The coordinates of point P in the coordinate system {O1} are , known and The position coordinates of point P in the coordinate system {O} can be calculated:

[0095]

[0096] It is known that the transformation relationship between the coordinate system {O} and the coordinate system {B} is Therefore, the position coordinates of point P in the coordinate system {B} can be calculated:

[0097]

[0098] According to the posture information obtained by formula (1.5) and the position information obtained by formula (1.8), the posture information of the moving platform coordinate system {M} relative to the static platform coordinate system {B} can be obtained.

[0099] See also Figure 1 As shown, when measuring the posture based on the two-dimensional inclination sensor, the rotation angle of the horizontal plane cannot be obtained. Therefore, when the parallel robot 3 rotates horizontally, the posture cannot be directly measured. To solve this problem, the present invention adds an additional offset ballbar 2 between the static platform and the dynamic platform of the parallel robot 3. The offset ballbar 2 includes a ballbar two-dimensional inclination sensor, a ballbar, a static platform magnetic base, and a dynamic platform magnetic base. Its installation position is offset from the center point of the static platform and the dynamic platform of the parallel robot 3. The position detection method of the offset ballbar 2 is the same as that of the central ballbar 1, and the position of its detection point is point P1. The detection point position detected by the central ballbar 1 is point P2. The line connecting points P1 and P2 is projected into the coordinate system {O}, and the angle between the line and the X-axis of the coordinate system {O} is the horizontal plane rotation angle of the dynamic platform of the parallel robot 3.

[0100] The known coordinate system conversion relationship and the coordinate system in the present invention are all known, and are calculated between conversion matrices realized by actually machining special hole positions. The above requirements require that the machining accuracy of the workpiece is better than the accuracy of the sensor itself.

[0101] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0102] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for calculating the posture of a parallel robot platform is implemented based on a device for detecting the posture of a parallel robot platform, wherein the device comprises a center ballbar (1), an offset ballbar (2), a moving platform two-dimensional inclination sensor (4), and a static platform two-dimensional inclination sensor (5); The upper and lower ends of the central ballbar (1) are respectively fixedly mounted on the center points of the moving platform and the static platform of the parallel robot (3); The moving platform two-dimensional inclination sensor (4) is fixedly mounted on the lower surface of the moving platform of the parallel robot (3); The static platform two-dimensional inclination sensor (5) is fixedly mounted on the upper surface of the static platform of the parallel robot (3); The offset ballbar (2) has the same structure as the central ballbar (1) and is arranged in parallel, and its installation position is offset from the center point of the static platform and the dynamic platform of the parallel robot (3); The central ballbar (1) comprises a static platform magnetic base (103), a dynamic platform magnetic base (101), a ballbar (102) and a ballbar two-dimensional inclination sensor (104); The static platform magnetic base (103) is fixedly connected to the static platform of the parallel robot (3), and the dynamic platform magnetic base (101) is fixedly connected to the dynamic platform of the parallel robot (3); The two ends of the ballbar (102) are respectively fixed in the static platform magnetic base (103) and the dynamic platform magnetic base (101), and the ballbar two-dimensional inclination sensor (104) is fixedly mounted on the ballbar (102); It is characterized in that The method comprises: When the parallel robot (3) is at the initial position, the directions of the X and Y axes of the moving platform two-dimensional inclination sensor (4) are kept consistent with the moving platform coordinate system of the parallel robot (3), and the directions of the X and Y axes of the stationary platform two-dimensional inclination sensor (5) are kept consistent with the stationary platform coordinate system of the parallel robot (3); The axial inclination angles output by the two-dimensional inclination sensor (4) of the moving platform and the two-dimensional inclination sensor (5) of the static platform are converted into Euler angles through data conversion, and the relative postures of the moving platform and the static platform are detected in combination with the detection points of the central ballbar (1) and the offset ballbar (2); The specific steps are as follows: Step 1: The two values ​​β and γ output by the two-dimensional inclinometer are the angles between its X-axis and Y-axis and the horizontal plane. The XOY plane of the reference coordinate system is parallel to the horizontal plane. Therefore, the angle output by the two-dimensional inclinometer in the X-axis direction is the rotation angle around the Y-axis. Step 2: Since the angle output in the Y-axis direction is not equal to the rotation angle around the X-axis, the rotation angle of the two-dimensional inclinometer around the Y-axis in the spatial coordinates is derived. The relationship between the rotation angle ω around the X-axis and the angles β and γ of the X-axis and Y-axis output by the two-dimensional inclination sensor; Step 3: When the reading of the static platform two-dimensional inclination sensor (5) is zero: Establish a reference coordinate system {O}, where the directions of the X and Y axes are the same as those of the inclinometer itself. According to the right-hand rule, the Z axis is vertically upward, and the origin of the coordinate system is located at the midpoint of the upper surface of the static platform. Establish a static platform coordinate system {B}. When the parallel robot is placed in an absolutely horizontal position, the static platform coordinate system {B} coincides with the reference coordinate system {O}. Establish the moving platform coordinate system {M}. When the parallel robot is at the absolute zero position, the moving platform coordinate system {M} is the static platform coordinate system {B} translated along the Z axis by a distance L, where L is the vertical distance between the moving and static platforms. According to the relationship obtained in step 2, the rotation angles α1, β1, α2, β2 of the moving and static platforms around the X-axis and Y-axis can be calculated from the readings of the static platform two-dimensional inclination sensor (5) and the dynamic platform two-dimensional inclination sensor (4), thereby calculating the rotation matrix of the dynamic and static platform coordinate systems {M}, {B} relative to the reference coordinate system {O} So we can get the rotation matrix between the moving and static platform coordinate systems Rotate according to the ZYX Euler angles in sequence, and the matrix is ​​described as: The Euler angles can be solved as follows: Step 4: According to step 2 and step 3, the posture data of the moving platform of the parallel robot (3) in the static platform coordinate system is obtained by combining the detection points of the central ballbar (1) and the offset ballbar (2).

2. The method for calculating the position and posture of a parallel robot platform according to claim 1, characterized in that: The derivation process of the relationship described in step 2 is: In spatial coordinates, assume that the straight line OE is perpendicular to the plane OAC and the plane BDE, so OE⊥BE, OE⊥BF, extend ED to F so that the straight line BF is parallel to the straight line AO, then ∠BFD=β, and BF⊥OB, therefore, BF⊥plane OBE, then BF⊥BE, so ∠DBE=∠BFD=β; From the triangular relationship, we can see that: The relationship between the output angle of the two-dimensional tilt sensor and the corresponding rotation angle can be obtained: That is, the rotation angle of the inclinometer around the Y axis in spatial coordinates The relationship between the rotation angle ω around the X-axis and the angles β and γ of the X-axis and Y-axis output by the inclinometer is shown in formula (1.2).

3. The method for calculating the position and posture of a parallel robot platform according to claim 1, characterized in that: The step 4 comprises: Step S1: establishing a coordinate system {I} of the ballbar two-dimensional inclination sensor (104), wherein the coordinate origin is located at the center of the ballbar (102); when the parallel robot (3) is at the initial zero position, the coordinate system {I} is the static platform coordinate system {B} translated by L1 along the positive direction of the Z axis, where L1 is the distance between the ballbar two-dimensional inclination sensor (104) mounted on the ballbar (102) and the static platform; Step S2: after the parallel robot (3) moves, the coordinate system {O1} is the coordinate system {O} rotated around the Y axis and the X axis by angles β and α, respectively, and the angles β and α are calculated by substituting the output angle of the ballbar two-dimensional inclination sensor (104) into the relationship derived in step 2; Coordinate system {I} is coordinate system {O1} translated by L1 along the positive direction of the Z axis, OP is the distance between the midpoints of the upper and lower platforms, recorded as L2, the value of L2 is known and can be read out by a ballbar (102); Calculate the rotation matrix based on the transformation relationship between coordinate system {O} and coordinate system {O1} Step S3: The coordinates of point P in the coordinate system {O1} are Known and Find the position coordinates of point P in the coordinate system {O}: It is known that the transformation relationship between the coordinate system {O} and the coordinate system {B} is Therefore, the position coordinates of point P in the coordinate system {B} can be calculated: Based on the posture information obtained by the Euler angle solution formula and the position information obtained by formula (1.8), the posture information of the moving platform coordinate system {M} relative to the static platform coordinate system {B} is obtained.

4. The method for calculating the posture of a parallel robot platform according to claim 1, characterized in that: The step 4 also includes: When the parallel robot (3) rotates horizontally, the detection point position P1 is detected by the offset ballbar (2), and the detection point position P2 is detected by the center ballbar (1). The line connecting the two points P1 and P2 is projected into the coordinate system {O}. The angle between the line and the X-axis of the coordinate system {O} is the horizontal plane rotation angle of the moving platform of the parallel robot (3).

Images