A position limiting measurement and control device of a Stewart platform parallel mechanism

Abstract

The application discloses a limiting measurement and control device of a Stewart platform parallel mechanism, which comprises a bottom plate, a six-dimensional motion platform is arranged on the upper side of the bottom plate, vertical columns are fixedly connected around the upper side of the bottom plate, and a test table is arranged on the vertical columns, a through hole is arranged in the middle of the test table, a ring is rotatably connected in the through hole, and the ring is provided with a following detection device.The slider is driven by a driving device to slide up and down in the through groove, the slider can rotate along with the ring, the height of the slider is controlled, the motion precision of the corresponding six-dimensional motion platform is tested, the displacement sensor is used for monitoring the change of the contact position, the six-dimensional motion platform moves along with the slider, the displacement sensor monitors the displacement change, and thus the motion precision of the six-dimensional motion platform is verified.

Description

Technical Field

[0001] This invention relates to the field of motion limit detection device technology, and in particular to a limit measurement and control device for a parallel mechanism of a Stewart platform. Background Technology

[0002] The Stewart platform parallel mechanism is a typical six-bar parallel mechanism, currently widely used in industries such as aviation, aerospace, subsea operations, underground mining, and manufacturing equipment. It consists of a fixed platform and a moving platform, connected by six electric cylinders. By driving each of the six cylinders individually, the moving platform can achieve six degrees of freedom of coordinated motion within a certain range.

[0003] Existing technologies, such as the limit control device for a parallel mechanism of a Stewart platform described in application number CN201520558611.8, use a pull rope at the bottom of the parallel mechanism of the Stewart platform for limit detection. Due to distance, the difference in the value of the attitude sensor readings is greater when the pull rope is installed at the center of the bottom of the Stewart platform and closer to the edge of the platform, depending on the angle of the pull rope. Furthermore, the position limit monitoring becomes less sensitive when the platform rotates by a certain angle, thus requiring improvement. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by proposing a limit control device for a parallel mechanism on a Stewart platform.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A limit measurement and control device for a parallel mechanism of a Stewart platform includes a base plate, a six-dimensional motion platform mounted on the upper side of the base plate, columns fixedly connected around the upper side of the base plate, and a test platform mounted on the columns. A through hole is provided in the middle of the test platform, and a circular ring is rotatably connected inside the through hole. A following detection device is mounted on the circular ring.

[0007] The following detection device includes a vertical plate, which is fixedly connected to the upper side of the ring. The vertical plate is provided with a through groove, in which a slider is slidably connected. The slider is fixedly connected to a horizontal plate, and a displacement sensor is fixedly connected to one end of the horizontal plate. The detection rod of the displacement sensor contacts the upper side of the six-dimensional motion platform.

[0008] It also includes a drive unit, which is used to drive the slider to slide within the through groove.

[0009] Preferably, the driving device includes a pad with slopes at both ends on the upper side. The pad is placed on the upper side of the test platform. The other end of the horizontal plate is fixedly connected to a hanging plate. The bottom of the hanging plate is rotatably connected to a roller, which can roll to the upper side of the pad. A support spring is fixedly connected between the slider and the top of the through groove.

[0010] Preferably, at least two pads are provided, and a guide groove is provided on the upper side of the test platform. The guide groove is arranged along the diameter direction of the test platform. A sliding block is slidably connected in the guide groove. The sliding block is fixedly connected to the bottom of the pad. A baffle is fixedly connected to the outer end of the guide groove. A lead screw is rotatably connected to the inner end of the guide groove. A servo motor is fixedly connected to the baffle. The main shaft of the servo motor is coaxially fixedly connected to the lead screw.

[0011] Preferably, the upper side of the six-dimensional motion platform is provided with a support base, the upper side of which is fixedly connected to a tray plate, and the upper side of the tray plate is provided with a spherical groove. The lower end of the detection rod of the displacement sensor is fixedly connected to a sphere, and the sphere is in matching contact with the spherical groove.

[0012] Preferably, the spherical groove is fixedly connected to the rubber membrane, the support plate has a cavity, and multiple rubber partitions are fixedly connected inside the cavity. The upper side of the rubber partitions is fixedly connected to the rubber membrane and forms multiple cavities. Multiple air pressure sensors are fixedly connected to the inner wall of the support plate, and the air pressure sensors are arranged corresponding to the cavities.

[0013] Preferably, an external gear ring is fixedly connected to the upper end of the ring, a first motor is fixedly connected to the test platform, and a drive gear is fixedly connected to the main shaft of the first motor, with the drive gear meshing with the external gear ring.

[0014] Preferably, multiple guide columns are fixedly connected to the bottom of the test platform, and lifting cylinders are fixedly connected to the sides of the columns, with the telescopic ends of the lifting cylinders fixedly connected to the bottom of the test platform.

[0015] The advantages of this invention are as follows: The limit measurement and control device of the Stewart platform parallel mechanism provided by this invention uses a slider to slide up and down in the through groove via a drive device, and the slider can follow the rotation of the ring to control the height of the slider. The corresponding six-dimensional motion platform is used to test the motion accuracy. That is, the six-dimensional motion platform follows the slider by raising one side or rotating the upper platform. The change of contact position is monitored by a displacement sensor. The displacement sensor monitors the displacement change as the six-dimensional motion platform moves with the slider, thereby verifying the motion accuracy of the six-dimensional motion platform.

[0016] This invention uses a sphere and a spherical groove to make contact, so that the tilt of the six-dimensional motion platform's platform can also be monitored by the spherical groove surrounding the displacement sensor's detection rod. At the same time, the cavity and air pressure sensor further monitor the displacement changes in the lateral direction, which is more than the single displacement sensor. This makes it easier to capture the situation of uncoordinated control motion of the six-dimensional motion platform, and makes the position limit test of the six-dimensional motion platform more complete. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the basic structure of the present invention;

[0018] Figure 2 yes Figure 1 Enlarged view of section E in the image;

[0019] Figure 3 This is a schematic diagram of the follow-up detection device in this invention;

[0020] Figure 4 This is a schematic diagram of the contact between the sphere and the support plate of the displacement sensor of the present invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0022] Example 1

[0023] like Figure 1-4 As shown, the present invention provides a limit measurement and control device for a parallel mechanism of a Stewart platform, including a base plate 1, a six-dimensional motion platform 2 mounted on the upper side of the base plate 1, columns 3 fixedly connected around the upper side of the base plate 1, a test platform 4 with multiple guide columns 31 fixedly connected to the bottom, lifting cylinders 32 fixedly connected to the sides of the columns 3, the telescopic ends of the lifting cylinders 32 being fixedly connected to the bottom of the test platform 4, the columns 3 together mounting the test platform 4, the test platform 4 having a through hole in the middle, a ring 41 rotatably connected inside the through hole, an external gear ring 42 fixedly connected to the upper end of the ring 41, a first motor fixedly connected to the test platform 4, the first motor being a servo motor capable of forward and reverse rotation, accurately positioning the rotation angle, the main shaft of the first motor fixedly connected to a drive gear 44, the drive gear 44 meshing with the external gear ring 42, and the ring 41 equipped with a following detection device;

[0024] The following detection device includes a vertical plate 5, which is fixedly connected to the upper side of the ring 41. The vertical plate 5 is provided with a through groove 51, and a slider 52 is slidably connected in the through groove 51. The slider 52 is fixedly connected to a horizontal plate 53, and a displacement sensor 54 is fixedly connected to one end of the horizontal plate 53. The detection rod of the displacement sensor 54 contacts the upper side of the six-dimensional motion platform 2.

[0025] It also includes a drive unit for driving the slider 52 to slide within the through groove 51.

[0026] Before testing, the lifting cylinder 32 raises the test platform 4, and the six-dimensional motion platform 2 moves to the base plate 1. The inner side of the ring 41 magnetically attracts the dial indicator, and the measuring rod of the dial indicator contacts the side of the six-dimensional motion platform 2. The ring 41 rotates one revolution to measure the coaxiality of the six-dimensional motion platform 2 and the through hole. Then, it is fixed to the base plate 1 by a pressure plate or bolts to install the six-dimensional motion platform 2.

[0027] During testing, slider 52 slides up and down within the through groove 51 via a drive device, and slider 52 can rotate with ring 41. The height of slider 52 is controlled, and the corresponding six-dimensional motion platform 2 is tested for motion accuracy. That is, the six-dimensional motion platform 2 follows slider 52 by raising one side or rotating the upper platform. The change in contact position is monitored by displacement sensor 54. The displacement change monitored by displacement sensor 54 is used to verify the motion accuracy of six-dimensional motion platform 2 as it moves with slider 52.

[0028] By using slider 52 for simple rotational and linear motion control, the accuracy of the six-dimensional motion platform 2 can be verified due to the maturity of the technology and the ease of ensuring accuracy. Specifically, the spatial displacement path (elevation change and rotation angle change) of the displacement sensor 54 is obtained based on the motion path of slider 52. The six-dimensional motion platform 2 calculates and simulates the theoretical input motion path parameters. The six-dimensional motion platform 2 performs corresponding actions according to the design parameters, which are synchronized with the spatial position change of the displacement sensor 54. The displacement change of the displacement sensor 54 is monitored, thereby demonstrating the operating accuracy of the six-dimensional motion platform 2.

[0029] Example 2

[0030] like Figure 1-4 As shown, the driving device includes a pad 6 with slopes at both ends of the upper side of the pad 6. The pad 6 is set on the upper side of the test platform 4. The other end of the horizontal plate 53 is fixedly connected to the hanging plate 61. The bottom of the hanging plate 61 is rotatably connected to the roller 62, which can roll to the upper side of the pad 6. The slider 52 is fixedly connected to the top of the through groove 51 with a support spring 63.

[0031] At least two pads 6 are provided. The upper side of the test bench 4 is provided with a guide groove 64. The guide groove 64 is arranged along the diameter direction of the test bench 4. A sliding block 65 is slidably connected in the guide groove 64. The sliding block 65 is fixedly connected to the bottom of the pad 6. A baffle 66 is fixedly connected to the outer end of the guide groove 64. A lead screw 67 is rotatably connected to the inner end of the guide groove 64. A servo motor 68 is fixedly connected to the baffle 66. The main shaft of the servo motor 68 is coaxially fixedly connected to the lead screw 67.

[0032] In this embodiment, the rotation of the servo motor 68 can drive the lead screw 67 to change the position of the slider 65, so that the corresponding pad 6 can move onto or away from the path of the roller 62. Through the slope of the pad 6 and the top of the pad 6, the roller 62 forms a corresponding elevation change, so that the six-dimensional motion platform 2 needs to control the motion so that the monitoring position of the six-dimensional motion platform 2 can follow the change of the slider 52 position. The roller 62 rolls to the slope of the pad 6 to measure the height rise and rotation synchronous motion control. The roller 62 only tests the rotation synchronous motion control on the top surface of the pad 6, thus increasing the variation in the test process, so as to detect more comprehensively and facilitate the detection of the motion control accuracy of the six-dimensional motion platform 2.

[0033] Example 3

[0034] like Figure 1-4 As shown, the six-dimensional motion platform 2 is provided with a support base 7 on its upper side. The support base 7 is attached to the table surface of the six-dimensional motion platform 2 by magnet, suction cup or adhesive. The support base 7 is fixedly connected to a tray 8 on its upper side. The tray 8 is provided with a spherical groove 81 on its upper side. The lower end of the detection rod of the displacement sensor 54 is fixedly connected to a ball 82. The ball 82 is in matching contact with the spherical groove 81.

[0035] The spherical groove 81 is fixedly connected to the rubber membrane 84. The support plate 8 has a cavity, and multiple rubber partitions 85 are fixedly connected inside the cavity. The upper side of the rubber partitions 85 is fixedly connected to the rubber membrane 84 and forms multiple cavities. Multiple air pressure sensors 86 are fixedly connected to the inner wall of the support plate 8, and the air pressure sensors 86 are arranged corresponding to the cavities.

[0036] like Figure 4 As shown, the platform of the six-dimensional motion platform 2 tilts during motion control. Since the detection rod of the displacement sensor 54 is generally in surface contact, the tilt of the platform will cause displacement error to the displacement sensor 54. This invention uses a sphere 82 and a spherical groove 81 to match and contact, so that the tilt of the platform of the six-dimensional motion platform 2 can also surround the detection rod of the displacement sensor 54 through the spherical groove 81. At the same time, the cavity and the air pressure sensor 86 monitor whether the sphere 82 squeezes the cavity from the side, further monitoring the displacement change in the lateral direction. This provides more directions than a single displacement sensor, making it easier to capture the situation of uncoordinated control of the six-dimensional motion platform 2, and making the position limit test of the six-dimensional motion platform 2 more complete.

[0037] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A limit measurement and control device for a Stewart platform parallel mechanism, comprising a base plate (1), a six-dimensional motion platform (2) mounted on the upper side of the base plate (1), and columns (3) fixedly connected around the upper side of the base plate (1), the columns (3) collectively mounting a test platform (4), characterized in that: The test bench (4) has a through hole in the middle, and a circular ring (41) is rotatably connected inside the through hole. The circular ring (41) is equipped with a follow-up detection device. The following detection device includes a vertical plate (5), which is fixedly connected to the upper side of the ring (41). The vertical plate (5) is provided with a through groove (51), and a slider (52) is slidably connected in the through groove (51). The slider (52) is fixedly connected to a horizontal plate (53). One end of the horizontal plate (53) is fixedly connected to a displacement sensor (54), and the detection rod of the displacement sensor (54) contacts the upper side of the six-dimensional motion platform (2). It also includes a drive unit for driving the slider (52) to slide within the through groove (51); The driving device includes a pad (6), with slopes at both ends of the upper side of the pad (6). The pad (6) is set on the upper side of the test bench (4). The other end of the horizontal plate (53) is fixedly connected to the hanging plate (61). The bottom of the hanging plate (61) is rotatably connected to a roller (62). The roller (62) can roll to the upper side of the pad (6). The slider (52) is fixedly connected to the top of the through groove (51) with a support spring (63). The upper end of the ring (41) is fixedly connected to the external gear ring (42), the test platform (4) is fixedly connected to the first motor, the main shaft of the first motor is fixedly connected to the drive gear (44), and the drive gear (44) meshes with the external gear ring (42).

2. The limit control device for a parallel mechanism of a Stewart platform according to claim 1, characterized in that: At least two pads (6) are provided. A guide groove (64) is provided on the upper side of the test platform (4). The guide groove (64) is arranged along the diameter direction of the test platform (4). A sliding block (65) is slidably connected in the guide groove (64). The sliding block (65) is fixedly connected to the bottom of the pad (6). A baffle (66) is fixedly connected to the outer end of the guide groove (64). A lead screw (67) is rotatably connected to the inner end of the baffle (66) and the guide groove (64). A servo motor (68) is fixedly connected to the baffle (66). The main shaft of the servo motor (68) is coaxially fixedly connected to the lead screw (67).

3. The limit control device for a parallel mechanism of a Stewart platform according to claim 1, characterized in that: The six-dimensional motion platform (2) is provided with a support base (7) on the upper side. A support plate (8) is fixedly connected to the upper side of the support base (7). A spherical groove (81) is provided on the upper side of the support plate (8). A ball (82) is fixedly connected to the lower end of the detection rod of the displacement sensor (54). The ball (82) and the spherical groove (81) are in matching contact.

4. The limit control device for a parallel mechanism of a Stewart platform according to claim 3, characterized in that: The spherical groove (81) is fixedly connected to the rubber membrane (84). The support plate (8) has a cavity, and multiple rubber partitions (85) are fixedly connected inside the cavity. The upper side of the rubber partitions (85) is fixedly connected to the rubber membrane (84) and forms multiple cavities. Multiple air pressure sensors (86) are fixedly connected to the inner wall of the support plate (8). The air pressure sensors (86) are set in correspondence with the cavities.

5. The limit control device for a parallel mechanism of a Stewart platform according to claim 1, characterized in that: The bottom of the test bench (4) is fixedly connected to multiple guide columns (31), and the side of the column (3) is fixedly connected to a lifting cylinder (32). The telescopic end of the lifting cylinder (32) is fixedly connected to the bottom of the test bench (4).

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