A reconfigurable parallel mechanism and a reconfiguration method

Abstract

The present invention discloses a reconfigurable parallel mechanism and a reconfiguration method, which belongs to the field of reconfigurable parallel mechanisms, including a fixed platform and a moving platform, wherein the fixed platform end position is movably linked with a support rod structure, the support rod structure is connected to the moving platform through a telescopic structure, a mode switching device is arranged on one side of the bottom of the fixed platform, and both the fixed platform and the moving platform are equilateral triangle structures. The present invention uses the above-mentioned reconfigurable parallel mechanism and the reconfiguration method to solve the problems of most reconfigurable parallel mechanisms currently on the market, such as complex structure, single motion mode, poor environmental adaptability, complex control system, and difficulty in meeting complex working conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of reconfigurable parallel mechanisms, and in particular to a reconfigurable parallel mechanism and a reconfiguration method. Background Art

[0002] With the rapid development of modern science and technology, the requirements for robots in all walks of life are increasing. Especially in extreme working environments such as (space exploration, deep-sea exploration, etc.), medical rehabilitation, intelligent manufacturing and other fields, the traditional parallel mechanism with fixed degrees of freedom has been difficult to meet the increasingly complex and changing task requirements due to its single topological structure and mechanism activity. Therefore, a reconfigurable parallel mechanism is needed to adapt to this change. However, most of the reconfigurable parallel mechanisms on the market currently have complex structures, single motion modes, poor environmental adaptability, complex control systems, and are difficult to meet complex working conditions. Summary of the invention

[0003] The purpose of the present invention is to provide a reconfigurable parallel mechanism and a reconstruction method, which are used to solve the problems that most reconfigurable parallel mechanisms currently on the market have complex structures, single motion modes, poor environmental adaptability, complex control systems, and difficulty in meeting complex working conditions.

[0004] To achieve the above-mentioned purpose, the present invention provides a reconfigurable parallel mechanism, including a fixed platform and a moving platform, wherein the end point of the fixed platform is movably connected with a support rod structure, the support rod structure is connected to the moving platform through a telescopic structure, a mode switching device is arranged on one side of the bottom end of the fixed platform, and both the fixed platform and the moving platform are equilateral triangle structures.

[0005] Preferably, the mode switching device includes a servo motor and a support frame, the output end of the servo motor is connected to a rotating gear, the first transmission mechanism and the second transmission mechanism are respectively arranged on both sides of the rotating gear, and the first transmission mechanism and the second transmission mechanism are respectively arranged on both sides of the support frame.

[0006] Preferably, the first transmission mechanism includes a transmission gear 1, which is connected to an electric push rod 1, the output shaft of the electric push rod 1 passes through a support frame and is connected to an active bevel gear 1, a passive bevel gear 1 is arranged on the left side of the active bevel gear 1, and a transmission bevel gear 1 is arranged on the right side of the active bevel gear 1, the shaft of the transmission bevel gear 1 is connected to a worm 1 through a coupling 1, the worm 1 is meshed with a worm wheel 1, a rotating shaft 1 is connected in the middle of the worm wheel 1, the rotating shaft 1 passes upward through a fixed platform and is connected to a support rod structure, the electric push rod 1 is rotatably arranged on the support frame, the passive bevel gear 1 and the transmission gear 1 are both rotatably arranged on the support frame, and the shaft of the transmission bevel gear 1 passes through the support frame and is connected to a coupling 1.

[0007] Preferably, the second transmission mechanism includes a second transmission gear, which is connected to an electric push rod, whose output shaft passes through a support frame and is connected to an active bevel gear, a second passive bevel gear is arranged on the right side of the active bevel gear, and a second transmission bevel gear is arranged on the left side of the active bevel gear. The shaft of the second transmission bevel gear is connected to a second worm through a second coupling, and the second worm is meshed with a second worm wheel. A second rotating shaft is connected in the middle of the second worm wheel, and the second rotating shaft passes upward through a fixed platform and is connected to a support rod structure. The second electric push rod is rotatably arranged on the support frame, and the second passive bevel gear and the second transmission gear are both rotatably arranged on the support frame, and the shaft of the second transmission bevel gear passes through the support frame and is connected to the second coupling.

[0008] Preferably, the support rod structure includes support rod one, support rod two and support rod three, and rotating shaft one and rotating shaft two are rotatably arranged at the first end point and the second end point of the fixed platform respectively, wherein one end of support rod one is fixedly connected to rotating shaft one, one end of support rod two is fixedly connected to rotating shaft two, one end of support rod three is fixedly connected to the third end point of the fixed platform, and a support block is arranged at the bottom end of the side of support rod three away from the fixed platform.

[0009] Preferably, the telescopic structure includes an electric telescopic rod 1, an electric telescopic rod 2 and an electric telescopic rod 3, wherein one end of the electric telescopic rod 1 is connected to an end of the support rod 1 away from the fixed platform through a rotating pair 1, the other end of the electric telescopic rod 1 is connected to the first end point of the moving platform through a ball pair 1, one end of the electric telescopic rod 2 is connected to an end of the support rod 2 away from the fixed platform through a rotating pair 2, the other end of the electric telescopic rod 2 is connected to the second end point of the moving platform through a ball pair 2, one end of the electric telescopic rod 3 is connected to an end of the support rod 3 away from the fixed platform through a universal joint 1, and the other end of the electric telescopic rod 3 is connected to the third end point of the moving platform through a universal joint 2.

[0010] Preferably, it includes a two-rotation and one-shift degree of freedom mode reconstruction method, a two-shift and two-rotation degree of freedom mode reconstruction method and a two-shift and one-rotation degree of freedom mode reconstruction method, which can convert the mechanism into a two-rotation and one-shift degree of freedom mode, a two-shift and two-rotation degree of freedom mode and a two-shift and one-rotation degree of freedom mode respectively.

[0011] Preferably, the two-rotation-one-translation degree of freedom mode reconstruction method comprises the steps of:

[0012] The first axis is named A1, the second axis is named A2, and the connection between the third support rod and the fixed platform is named A3;

[0013] Name the first ball joint C1, the second ball joint C2, and the second universal joint C3;

[0014] Name the first revolute pair B1, the second revolute pair B2, and the first universal joint B3;

[0015] The mode switching device drives the rotating shaft 1 and the rotating shaft 2 to rotate respectively, and then drives the support rod 1 and the support rod 2 to rotate respectively, and the electric telescopic rod 1, the electric telescopic rod 2, and the electric telescopic rod 3 are extended or shortened, so that the angle between the line A1B1 and the line A1A2 is 120°, the angle between the line A2B2 and the line A1A2 is 120°, and the three lines A1C1, A2C2, and A3C3 are perpendicular to the ground. At this time, it is a two-rotation and one-translation freedom mode.

[0016] Preferably, the two-translation and two-rotation degree-of-freedom mode reconstruction method comprises the steps of:

[0017] The mode switching device drives the rotating shaft 1 and the rotating shaft 2 to rotate respectively, and then drives the support rod 1 and the support rod 2 to rotate respectively, and the electric telescopic rod 1, the electric telescopic rod 2, and the electric telescopic rod 3 are extended or shortened, so that the angle between the line A1B1 and the line A1A3 is 120°, and the angle between the line A2B2 and the line A2A3 is 120°. At this time, the three lines A1C1, A2C2, and A3C3 are perpendicular to the ground. At this time, it is a two-shift and two-rotation freedom mode.

[0018] Preferably, the two-translation-one-rotation degree-of-freedom mode reconstruction method comprises the steps of:

[0019] The mode switching device drives the rotating shaft 1 and the rotating shaft 2 to rotate respectively, and then drives the support rod 1 and the support rod 2 to rotate respectively, and the electric telescopic rod 1, the electric telescopic rod 2, and the electric telescopic rod 3 are extended or shortened, so that the angle between the line A1B1 and the line A1A2 is 90°, and the angle between the line A2B2 and the line A1A2 is 90°. At this time, the three lines A1C1, A2C2, and A3C3 are perpendicular to the ground. At this time, it is a two-movement and one-rotation freedom mode.

[0020] Therefore, the present invention adopts the above-mentioned reconfigurable parallel mechanism and reconstruction method, which can arbitrarily switch between the three degrees of freedom modes of two rotations and one translation, two translations and one rotation, and two translations and two rotations, and the mode switching does not require reassembly of the structure. When switching, the original posture of the moving platform will not be changed. After switching, it has the ability of mode self-locking and will not passively switch modes. On the basis of the three modes, each mode derives three different branch chain arrangements. When the branch chain arrangements are different, although the number and type of degrees of freedom will not change, the corresponding performance and workspace will be different. It has different functions for different environments, which solves the problems of most reconfigurable parallel mechanisms on the market that have complex structures, single motion modes, poor environmental adaptability, complex control systems, and difficulty in meeting complex working conditions.

[0021] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1It is a structural schematic diagram of an embodiment of a reconfigurable parallel mechanism of the present invention;

[0023] Figure 2 A top view of an embodiment of a reconfigurable parallel mechanism mode switching device of the present invention;

[0024] Figure 3 It is a structural schematic diagram of an embodiment of a reconfigurable parallel mechanism mode switching device of the present invention;

[0025] Figure 4 The branch distribution of a reconfigurable parallel mechanism in each mode of the present invention;

[0026] Figure 5 A three-dimensional model diagram of the branch chain distribution in each mode of a reconfigurable parallel mechanism of the present invention;

[0027] Figure 6 It is a structural schematic diagram of a reconfigurable parallel mechanism in a two-rotation-one-translation degree of freedom mode of the present invention;

[0028] Figure 7 It is a structural schematic diagram of a reconfigurable parallel mechanism in a two-translation-one-rotation degree of freedom mode of the present invention;

[0029] Figure 8 It is a structural schematic diagram of a reconfigurable parallel mechanism in a two-translation and two-rotation degree-of-freedom mode of the present invention;

[0030] Fig. 9 A schematic diagram of a coordinate system of a motion equation of a reconfigurable parallel mechanism in a two-rotation-one-translation degree of freedom mode of the present invention;

[0031] Fig.10 A schematic diagram of a coordinate system of a motion equation of a reconfigurable parallel mechanism in a two-translation-one-rotation degree-of-freedom mode of the present invention;

[0032] Fig.11 A schematic diagram of a coordinate system of a motion equation of a reconfigurable parallel mechanism in a two-translation and two-rotation degree-of-freedom mode of the present invention;

[0033] Fig.12 It is a displacement diagram of the dynamic platform posture changing with time in each mode of a reconfigurable parallel mechanism of the present invention;

[0034] Fig.13 It is a posture change diagram of a moving platform of each branch chain state in a two-rotation and one-translation degree of freedom mode of a reconfigurable parallel mechanism of the present invention;

[0035] Fig.14 It is a posture change diagram of a moving platform of each branch chain state in a two-translation and one-rotation degree of freedom mode of a reconfigurable parallel mechanism of the present invention;

[0036] Fig.15This is a dynamic platform posture change diagram of each branch state in a two-translation and two-rotation degree of freedom mode of a reconfigurable parallel mechanism of the present invention.

[0037] Reference numerals

[0038] 1. Support block; 2. Support rod three; 3. Fixed platform; 4. Rotating shaft one; 5. Mode switching device; 51. Servo motor; 52. Rotating gear; 53. Transmission gear one; 54. Electric push rod one; 55. Support frame; 56. Worm gear one; 57. Worm one; 58. Coupling one; 59. Transmission bevel gear one; 510. Active bevel gear one; 511. Passive bevel gear one; 512. Passive bevel gear two; 513. Active bevel gear two; 514 , transmission bevel gear two; 515, coupling two; 516, worm gear two; 517, worm gear two; 518, electric push rod two; 519, transmission gear two; 6, support rod one; 7, rotating pair one; 8, electric telescopic rod one; 9, ball pair one; 10, ball pair two; 11, rotating shaft two; 12, support rod two; 13, rotating pair two; 14, electric telescopic rod two; 15, universal joint one; 16, electric telescopic rod three; 17, universal joint two; 18, moving platform. DETAILED DESCRIPTION

[0039] Example

[0040] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0041] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] In the description of the present invention, it should be noted that the terms "upper", "lower", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or are directions or positional relationships in which the product of the invention is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0043] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "setting", "installation" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0044] Some embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0045] like Figures 1 to 3 A reconfigurable parallel mechanism shown in the figure includes a fixed platform 3 and a moving platform 18, a support rod structure is arranged at the end position of the fixed platform 3, a telescopic structure is arranged on the side of the support rod structure away from the moving platform 18, one side of the telescopic structure is movably connected to the support rod structure, and the side of the telescopic structure away from the support rod structure is movably connected to the moving platform 18, a mode switching device 5 is arranged on one side of the bottom end of the fixed platform 3, and the fixed platform 3 and the moving platform 18 are both equilateral triangle structures.

[0046] The mode switching device 5 includes a servo motor 51 and a support frame 55 . The output end of the servo motor 51 is connected to a rotating gear 52 . A first transmission mechanism and a second transmission mechanism are respectively arranged on both sides of the rotating gear 52 . The first transmission mechanism and the second transmission mechanism are respectively arranged on both sides of the support frame 55 .

[0047] The first transmission mechanism includes a transmission gear 53, which is connected to an electric push rod 54. The output shaft of the electric push rod 54 passes through a support frame 55 and is connected to an active bevel gear 510. A passive bevel gear 511 is arranged on the left side of the active bevel gear 510, and a transmission bevel gear 59 is arranged on the right side of the active bevel gear 510. The shaft of the transmission bevel gear 59 is connected to a worm 57 through a coupling 58. The worm 57 is meshed with a worm wheel 56. A rotating shaft 4 is connected in the middle of the worm wheel 56. The rotating shaft 4 passes upward through the fixed platform 3 and is fixedly connected to the support rod structure. The electric push rod 54 is rotationally connected to the support frame 55. The passive bevel gear 511 and the transmission bevel gear 59 are both rotatably arranged on the support frame 55. The shaft of the transmission bevel gear 59 passes through the support frame 55 and is connected to a coupling 58.

[0048] The second transmission mechanism includes a transmission gear 519, which is connected to an electric push rod 518. The output shaft of the electric push rod 518 passes through the support frame 55 and is connected to an active bevel gear 513. A passive bevel gear 512 is arranged on the right side of the active bevel gear 513, and a transmission bevel gear 514 is arranged on the left side of the active bevel gear 513. The shaft of the transmission bevel gear 514 is connected to a worm 516 through a coupling 515. The worm 516 is meshed with a worm wheel 517. A rotating shaft 4 is connected to the middle of the worm wheel 517. The rotating shaft 4 passes upward through the fixed platform 3 and is fixedly connected to the support rod structure. The electric push rod 518 is rotationally connected to the support frame 55. The passive bevel gear 512 and the transmission bevel gear 514 are both rotatably arranged on the support frame 55. The shaft of the transmission bevel gear 514 passes through the support frame 55 and is connected to the coupling 515.

[0049] The support frame 55 is provided with a mounting seat, and a mounting hole is provided in the center of the mounting seat. The electric push rod 1 54 and the electric push rod 2 518 are rotatably sleeved in the mounting hole. When the electric push rod 1 54 pushes the transmission gear 1 53 backward and pushes the active bevel gear 1 510 forward, they will not affect each other. By adjusting the electric push rod 1 54, the positions of the transmission gear 1 53 and the active bevel gear 1 510 can be adjusted arbitrarily and separately, and the effect of rotation transmission can be achieved at the same time. Due to the symmetric structure, the electric push rod 2 518 has the same effect.

[0050] The mode switching device 5 is mainly transmitted through a gear set. The servo motor 51 is fixed by a mounting seat with bolts, and the support frame 55 is fixed by bolts. When switching, the servo motor 51 is used as input, and the input of the motor is transmitted separately through the transmission gear 1 53 and the transmission gear 2 519. When the electric push rod 1 54 works, the active bevel gear 1 510 is pushed forward. At this time, the active bevel gear 1 510 and the transmission bevel gear 1 59 are meshed, and the motion is transmitted to the worm 1 57. At the same time, the active bevel gear 1 510 is meshed with the passive bevel gear 1 511. The passive bevel gear 1 511 has the function of making the transmission between the active bevel gear 1 510 and the transmission bevel gear 1 59 more stable.

[0051] Then, through the combination of worm gear 1 56 and worm gear 1 57, the motion is transmitted from worm gear 1 57 to shaft 1 4, thereby realizing the rotation of shaft 1 4. Similarly, due to the symmetry of the structure, the motion transmission of shaft 2 11 is similar to that of shaft 1 4. It is worth noting that the input of servo motor 51 is successfully separated through transmission gear 1 53 and transmission gear 2 519. The mode switching device 5 of the present invention can control shaft 1 4 and shaft 2 11 at the same time, and can also control shaft 1 4 and shaft 2 11 separately as needed. At the same time, since the final motion is transmitted through worm gear 1 56, worm gear 1 57 and worm gear 2 517 and worm gear 2, the self-locking characteristics of the worm gear structure are retained, so that the mode switching device 5 has a self-locking function and will not passively switch modes.

[0052] The support rod structure includes support rod one 6, support rod two 12 and support rod three 2, which are respectively arranged at the three end positions of the fixed platform 3, wherein one end of support rod one 6 is fixedly connected to the rotating shaft one 4, support rod two 12 is fixedly connected to the rotating shaft two 11, support rod three 2 is fixedly set on the fixed platform 3, and a support block 1 is set at the bottom end of the side of support rod three 2 away from the fixed platform 3.

[0053] The telescopic structure includes an electric telescopic rod 18, an electric telescopic rod 214 and an electric telescopic rod 316, wherein one end of the electric telescopic rod 18 is connected to an end of the support rod 16 away from the fixed platform 3 through a rotating joint 17, the other end of the electric telescopic rod 18 is connected to the end point corresponding to the moving platform 18 through a ball joint 19, one end of the electric telescopic rod 214 is connected to an end of the support rod 212 away from the fixed platform 3 through a rotating joint 13, the other end of the electric telescopic rod 214 is connected to the end point corresponding to the moving platform 18 through a ball joint 10, one end of the electric telescopic rod 316 is connected to an end of the support rod 32 away from the fixed platform 3 through a universal joint 15, and the other end of the electric telescopic rod 316 is connected to the end point corresponding to the moving platform 18 through a universal joint 217.

[0054] like Figures 4 to 15 As shown, the mode switching device 5 can be adjusted to change the mode of the reconfigurable parallel mechanism. The reconfigurable parallel mechanism has three modes: two rotation and one shift degree of freedom, two shift and two rotation degrees of freedom, and two shift and one rotation degree of freedom. The three modes have different degrees of freedom. Each mode derives three different branch chain arrangements. After switching the mode, it has self-locking ability and will not passively switch the mode. The rotating shaft 1 4 is named A1, the rotating shaft 2 11 is named A2, and the connection between the support rod 3 2 and the fixed platform 3 is named A3;

[0055] The ball joint 1 9 is named C1, the ball joint 2 10 is named C2, and the universal joint 2 17 is named C3; the revolute joint 1 7 is named B1, the revolute joint 2 13 is named B2, and the universal joint 15 is named B3.

[0056] When the arrangement of the branches is different, although the number and type of degrees of freedom will not change, the corresponding performance and workspace will be different. It can play a certain role in different environments. The relationship between the state of the axis 1 4 and the axis 2 11 and each branch is as follows:

[0057] Axis 1 Axis 2 model Axis 1 Axis 2 model 0 0 (a) 60° / -300° -120° / 240° (g) ±180° 0 (b) -120° / 240° 60° / -300° (h) 0 ±180° (c) -30° / 330° -30° / 330° (i) ±180° ±180° (d) 150° / -210° 30° / 330° (j) 60° / -300° 60° / -300° (e) -30° / 330° -150° / -210° (k) -120° / 240° -120° / 240° (f) -150° / -210° -150° / -210° (l)

[0058] In the two-rotation-one-translation degree of freedom mode, the angle between line A1B1 and line A1A2 is 120°, and the angle between line A2B2 and line A1A2 is 120°. At this time, lines A1C1, A2C2, and A3C3 are perpendicular to the ground.

[0059] The rotation axis of the revolving pair 17 represented by B1 is parallel to the ground and parallel to A2A3. The rotation axis of the revolving pair 213 represented by B2 is parallel to the ground and parallel to A1A3. The two rotation axes of the universal joint 15 represented by B3 are both parallel to the ground, and the axis closer to the ground is parallel to A1A2. The two rotation axes of the universal joint 217 represented by C3 are both parallel to the ground, and the axis closer to the ground is parallel to A1A2. At the same time, the axes corresponding to B3 and C3 are parallel to each other. Through the screw theory, it can be deduced that in the two-rotation-one-translation mode, the parallel mechanism has two rotational degrees of freedom around the u and v axes and a translational degree of freedom along the w axis.

[0060] Based on the initial model Figure 6 As shown, through the mode switching device 5, a configuration with the same degree of freedom type can be evolved, such as Figure 4 and Figure 5 (b)-(d) in the figure, configuration (b)-(d) is obtained by controlling the rotation shaft 1 4 and the rotation shaft 2 11 to rotate a certain angle through the mode switching device 5 in configuration (a), and the specific rotation angles of the rotation shaft 1 4 and the rotation shaft 2 11 are shown in the table.

[0061] In the two-translation-one-rotation degree of freedom mode, the angle between line A1B1 and line A1A2 is 90°, and the angle between line A2B2 and line A1A2 is 90°. At this time, lines A1C1, A2C2, and A3C3 are perpendicular to the ground.

[0062] At this time, the support rod 16 and the support rod 2 12 are perpendicular to A1A2. At this time, the rotation axis of the rotation pair 1 7 represented by B1 is parallel to the ground and parallel to A1A2. The rotation axis of the rotation pair 2 13 represented by B2 is parallel to the ground and parallel to A1A2. The two rotation axes of the universal joint 15 represented by B3 are both parallel to the ground, and the axis close to the ground is parallel to A1A2. The two rotation axes of the universal joint 2 17 represented by C3 are both parallel to the ground, and the axis close to the ground is parallel to A1A2. At the same time, the corresponding axes of B3 and C3 are parallel to each other. Through the screw theory, it can be deduced that the two-translation and two-rotation freedom mode has two degrees of freedom of movement along the u and w axes and one degree of freedom of rotation around the u axis.

[0063] Based on the initial model Figure 7 As shown, through the mode switching device 5, a configuration with the same degree of freedom type can be evolved, such as Figure 4 and Figure 5 (f)-(h) in the figure, configuration (f)-(h) is obtained by controlling the rotation shaft 1 4 and the rotation shaft 2 11 of configuration (e) by the mode switching device 5 to rotate a certain angle, and the specific rotation angles of the rotation shaft 1 4 and the rotation shaft 2 11 are shown in the table.

[0064] In the two-translation and two-rotation degrees of freedom mode, the angle between line A1B1 and line A1A3 is 120°, and the angle between line A2B2 and line A2A3 is 120°. At this time, lines A1C1, A2C2, and A3C3 are perpendicular to the ground.

[0065] At this time, the support rod 1 6 and the support rod 2 12 are parallel to each other and intersect, and coincide with the line between the two points A1A2. At this time, the rotation axis of the rotation pair 1 7 represented by B1 is parallel to the ground and perpendicular to A1A2. The rotation axis of the rotation pair 2 13 represented by B2 is parallel to the ground and perpendicular to A1A2. The two rotation axes of the universal joint 1 15 represented by B3 are both parallel to the ground, and the axis close to the ground is parallel to A1A2. The two rotation axes of the universal joint 2 17 represented by C3 are both parallel to the ground, and the axis close to the ground is parallel to A1A2. At the same time, the corresponding axes of B3 and C3 are parallel to each other. Through the screw theory, it can be deduced that this mode has two degrees of freedom of movement along the u and w axes and two degrees of freedom of rotation around the u and v axes.

[0066] Based on the initial model Figure 8 As shown, through the mode switching device 5, a configuration with the same degree of freedom type can be evolved, such as Figure 4 and Figure 5(j)-(l) in the figure, configuration (j)-(l) is obtained by controlling the rotation shaft 1 4 and the rotation shaft 2 11 to rotate a certain angle through the mode switching device 5 in configuration (i), and the specific rotation angles of the rotation shaft 1 4 and the rotation shaft 2 11 are shown in the table.

[0067] Here are the solutions to the equations of motion for the three modes:

[0068] The pose transformation matrix is:

[0069]

[0070] These three matrices are the change matrices of the pose transformation between different coordinate systems, R X , R Y , R Z The matrices corresponding to the rotation of the moving platform 18 around the x, y, and z axes in space are used to determine the use of the posture change matrix according to the degree of freedom mode of the parallel mechanism during calculation. α represents the rotation angle of the moving platform 18 around the x-axis, β represents the rotation angle of the moving platform 18 around the y-axis, and γ represents the rotation angle of the moving platform 18 around the z-axis.

[0071] The equation of motion for the two-rotational-one-translational mode is calculated as follows:

[0072] Establish the fixed coordinate system p1-u1v1w1 and the moving coordinate system o1-x1y1z1 respectively, such as Fig. 9 The position coordinates of the endpoints of each connecting branch of the fixed platform 3 in the fixed coordinate system are:

[0073]

[0074] Wherein T represents the transpose of the matrix, a represents the distance from the center of the support block 1 to the center of the equilateral triangle where the fixed platform 3 is located, and b represents the distance from the axis of the rotation axis 1 4 or the rotation axis 2 11 to the center of the triangle.

[0075] The coordinates of each end point of the moving platform 18 in the moving coordinate system are:

[0076]

[0077] b represents the distance from the axis of the rotation axis 1 4 or the rotation axis 2 11 to the center of the triangle.

[0078] The moving platform 18 can rotate around the two axes x1 and y1, so the conversion relationship between the moving coordinate system and the fixed coordinate system is:

[0079]

[0080] In the formula, c represents cosine, s represents sin, α represents the rotation angle of the moving platform 18 around the x-axis, and β represents the rotation angle of the moving platform 18 around the y-axis.

[0081] The coordinates of o1 in the moving coordinate system can be expressed as:

[0082] o1=[0 0 z] T (4);

[0083] The inverse kinematics equation of the parallel mechanism is mainly to obtain the mapping relationship between input and output. Fig. 9 , a relationship can be established:

[0084] p i A i +A i B i =p i o i +o i B i (i=1, 2, 3) (5);

[0085] In this formula, A1B1 is the input of the entire parallel mechanism, and the expression on the right side of the equal sign contains the output parameter, that is, the formula itself is a mapping relationship between input and output. At the same time, the construction of this formula is based on the fixed coordinate system p1-u1v1w1.

[0086] Based on formula (1) to formula (5), the mapping relationship between input and output can be obtained, which is the inverse kinematics equation (6) of the two-rotation-one-translation mode:

[0087]

[0088] Wherein c represents cos, s represents sin, α represents the rotation angle of the moving platform 18 around the x-axis, β represents the rotation angle of the moving platform 18 around the y-axis, a represents the distance from the center of the support block 1 to the center of the equilateral triangle where the fixed platform 3 is located, and b represents the distance from the axis of the rotating shaft 1 4 or the rotating shaft 2 11 to the center of the triangle.

[0089] The equation of motion for the two-translation-one-rotation mode is calculated as follows:

[0090] Establish the fixed coordinate system p2-u2v2w2 and the moving coordinate system o2-x2y2z2 respectively, such as Fig.10 As shown, the position coordinates of the endpoints of each connecting branch of the fixed platform 3 in the fixed coordinate system are:

[0091]

[0092] a represents the distance from the center of the support block 1 to the center of the equilateral triangle where the fixed platform 3 is located, and b represents the distance from the axis of the rotating shaft 1 4 or the rotating shaft 2 11 to the center of the triangle.

[0093] The coordinates of each end point of the moving platform 18 in the moving coordinate system are:

[0094]

[0095] a represents the distance from the center of the support block 1 to the center of the equilateral triangle where the fixed platform 3 is located, and b represents the distance from the axis of the rotating shaft 1 4 or the rotating shaft 2 11 to the center of the triangle.

[0096] The moving platform 18 can rotate around the x2 axis, so the conversion relationship between the moving coordinate system and the fixed coordinate system is:

[0097]

[0098] In the formula, c represents cosine, s represents sin, and α represents the rotation angle of the moving platform 18 around the x-axis.

[0099] In the two-translation-one-rotation mode, the mechanism has two translation degrees of freedom and one rotation degree of freedom, so the coordinates of o2 in the moving coordinate system can be expressed as:

[0100] o2=[0 yz] T (10);

[0101] Based on formula (7) to formula (10) and formula (5), the mapping relationship between input and output can be obtained, which is the inverse kinematics equation of the two-translation-one-rotation degree of freedom mode.

[0102]

[0103] Wherein c represents cos, s represents sin, α represents the rotation angle of the moving platform 18 around the x-axis, a represents the distance from the center of the support block 1 to the center of the equilateral triangle where the fixed platform 3 is located, and b represents the distance from the axis of the rotating shaft 1 4 or the rotating shaft 2 11 to the center of the triangle.

[0104] The equation of motion for the two-translation and two-rotational degree of freedom mode is calculated as follows:

[0105] Establish the fixed coordinate system p3-u3v3w3 and the moving coordinate system o3-x3y3z3 respectively, such as Fig.11 As shown, the position coordinates of the endpoints of each connecting branch of the fixed platform 3 in the fixed coordinate system are:

[0106]

[0107] a represents the distance from the center of the support block 1 to the center of the equilateral triangle where the fixed platform 3 is located, and b represents the distance from the axis of the rotating shaft 1 4 or the rotating shaft 2 11 to the center of the triangle.

[0108] The coordinates of each end point of the moving platform 18 in the moving coordinate system are:

[0109]

[0110] b represents the distance from the axis of the rotation axis 1 4 or the rotation axis 2 11 to the center of the triangle.

[0111] The moving platform 18 can rotate around the two axes x3 and y3, so the conversion relationship between the moving coordinate system and the fixed coordinate system is:

[0112]

[0113] Wherein c represents cosine, s represents sin, α represents the rotation angle of the moving platform 18 around the x-axis, and β represents the rotation angle of the moving platform 18 around the y-axis.

[0114] In the two-translation and two-rotation freedom mode, the mechanism has two translation degrees of freedom and one rotation degree of freedom, so the coordinates of o3 in the moving coordinate system can be expressed as:

[0115] o3=[x 0 z] T (15);

[0116] Based on formula (12) to formula (15) and formula (5), the mapping relationship between input and output can be obtained, which is the inverse kinematics equation of the two-translation and two-rotation degree of freedom mode.

[0117]

[0118] Wherein c represents cos, s represents sin, α represents the rotation angle of the moving platform 18 around the x-axis, β represents the rotation angle of the moving platform 18 around the y-axis, a represents the distance from the center of the support block 1 to the center of the equilateral triangle where the fixed platform 3 is located, and b represents the distance from the axis of the rotating shaft 1 4 or the rotating shaft 2 11 to the center of the triangle.

[0119] After the kinematic equations of each motion mode are obtained, the change images of each input are obtained by giving the posture parameter change function of the moving platform 18, so as to analyze the mapping relationship between input and output in more detail.

[0120] The two-rotation-one-translation freedom mode gives the posture change function of the moving platform 18:

[0121]

[0122] The two-translation-one-rotation freedom mode gives the posture change function of the moving platform 18:

[0123]

[0124] The two-translation and two-rotation freedom mode gives the posture change function of the moving platform 18:

[0125]

[0126] In formulas (17) to (19), x and y represent the rotation angles around the x and y axes, respectively, and u, v, and w represent the displacements along the x, y, and z axes, respectively.

[0127] exist Fig.12 In the figure, from left to right are the displacement diagrams of the moving platform 18 postures changing with time in the two-rotation and one-translation degree of freedom mode, the two-translation and one-rotation degree of freedom mode, and the two-translation and two-rotation degree of freedom mode.

[0128] Therefore, the present invention adopts the above-mentioned reconfigurable parallel mechanism and reconstruction method, which can arbitrarily switch between the three degrees of freedom modes of two rotations and one translation, two translations and one rotation, and two translations and two rotations, and the mode switching does not require reassembly of the structure. When switching, the original posture of the moving platform will not be changed. After switching, it has the ability of mode self-locking and will not passively switch modes. On the basis of the three modes, each mode derives three different branch chain arrangements. When the branch chain arrangements are different, although the number and type of degrees of freedom will not change, the corresponding performance and workspace will be different. It can play a certain role in different environments, solving the problems of most reconfigurable parallel mechanisms on the market that have complex structures, single motion modes, poor environmental adaptability, complex control systems, and difficulty in meeting complex working conditions.

[0129] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A reconfigurable parallel mechanism, characterized in that: It includes a fixed platform and a moving platform. The end point of the fixed platform is movably connected with a support rod structure, which is connected to the moving platform through a telescopic structure. A mode switching device is arranged on one side of the bottom end of the fixed platform. Both the fixed platform and the moving platform are equilateral triangle structures. The mode switching device includes a servo motor and a support frame, the output end of the servo motor is connected to a rotating gear, the two sides of the rotating gear are respectively provided with a first transmission mechanism and a second transmission mechanism, and the first transmission mechanism and the second transmission mechanism are respectively provided on the two sides of the support frame; The first transmission mechanism includes a transmission gear 1, the transmission gear 1 is connected to an electric push rod 1, the output shaft of the electric push rod 1 passes through a support frame and is connected to an active bevel gear 1, a passive bevel gear 1 is arranged on the left side of the active bevel gear 1, and a transmission bevel gear 1 is arranged on the right side of the active bevel gear 1, the shaft of the transmission bevel gear 1 is connected to a worm 1 through a coupling 1, the worm 1 is meshed with a worm wheel 1, a rotating shaft 1 is connected in the middle of the worm wheel 1, the rotating shaft 1 passes upward through a fixed platform and is connected to a support rod structure, the electric push rod 1 is rotatably arranged on the support frame, the passive bevel gear 1 and the transmission gear 1 are both rotatably arranged on the support frame, and the shaft of the transmission bevel gear 1 passes through the support frame and is connected to a coupling 1; The second transmission mechanism includes a transmission gear 2, the transmission gear 2 is connected to an electric push rod 2, the output shaft of the electric push rod 2 passes through the support frame and is connected to an active bevel gear 2, a passive bevel gear 2 is arranged on the right side of the active bevel gear 2, and a transmission bevel gear 2 is arranged on the left side of the active bevel gear 2, the shaft of the transmission bevel gear 2 is connected to the worm 2 through a coupling 2, the worm 2 is meshed with a worm wheel 2, and a rotating shaft 2 is connected in the middle of the worm wheel 2, the rotating shaft 2 passes upward through the fixed platform and is connected to the support rod structure, the electric push rod 2 is rotatably arranged on the support frame, the passive bevel gear 2 and the transmission gear 2 are both rotatably arranged on the support frame, and the shaft of the transmission bevel gear 2 passes through the support frame and is connected to the coupling 2; The support rod structure includes support rod 1, support rod 2 and support rod 3, and the rotating shaft 1 and the rotating shaft 2 are rotatably arranged at the first end point and the second end point of the fixed platform respectively, wherein one end of the support rod 1 is fixedly connected to the rotating shaft 1, one end of the support rod 2 is fixedly connected to the rotating shaft 2, one end of the support rod 3 is fixedly connected to the third end point of the fixed platform, and a support block is arranged at the bottom end of the side of the support rod 3 away from the fixed platform; The telescopic structure includes an electric telescopic rod 1, an electric telescopic rod 2 and an electric telescopic rod 3, wherein one end of the electric telescopic rod 1 is connected to an end of a support rod 1 away from a fixed platform through a rotating pair 1, the other end of the electric telescopic rod 1 is connected to a first end point of a moving platform through a ball pair 1, one end of the electric telescopic rod 2 is connected to an end of a support rod 2 away from the fixed platform through a rotating pair 2, the other end of the electric telescopic rod 2 is connected to a second end point of the moving platform through a ball pair 2, one end of the electric telescopic rod 3 is connected to an end of the support rod 3 away from the fixed platform through a universal joint 1, and the other end of the electric telescopic rod 3 is connected to a third end point of the moving platform through a universal joint 2.

2. The method for reconfiguring a reconfigurable parallel mechanism according to claim 1, characterized in that: It includes a two-rotation-one-translation degree of freedom mode reconstruction method, a two-translation-two-rotation degree of freedom mode reconstruction method and a two-translation-one-rotation degree of freedom mode reconstruction method, which converts the mechanism into a two-rotation-one-translation degree of freedom mode, a two-translation-two-rotation degree of freedom mode and a two-translation-one-rotation degree of freedom mode respectively.

3. The method for reconfiguring a reconfigurable parallel mechanism according to claim 2, characterized in that: The two-rotation-one-translation degree of freedom mode reconstruction method comprises the following steps: The first axis is named A1, the second axis is named A2, and the connection between the third support rod and the fixed platform is named A3; Name the first ball joint C1, the second ball joint C2, and the second universal joint C3; Name the first revolute pair B1, the second revolute pair B2, and the first universal joint B3; The mode switching device drives the rotating shaft 1 and the rotating shaft 2 to rotate respectively, and then drives the support rod 1 and the support rod 2 to rotate respectively, and the electric telescopic rod 1, the electric telescopic rod 2, and the electric telescopic rod 3 are extended or shortened, so that the angle between the line A1B1 and the line A1A2 is 120°, the angle between the line A2B2 and the line A1A2 is 120°, and the three lines A1C1, A2C2, and A3C3 are perpendicular to the ground. At this time, it is a two-rotation and one-translation freedom mode.

4. The method for reconfiguring a reconfigurable parallel mechanism according to claim 3, characterized in that: The two-translation and two-rotation degree of freedom mode reconstruction method comprises the following steps: The mode switching device drives the rotating shaft 1 and the rotating shaft 2 to rotate respectively, and then drives the support rod 1 and the support rod 2 to rotate respectively, and the electric telescopic rod 1, the electric telescopic rod 2, and the electric telescopic rod 3 are extended or shortened, so that the angle between the line A1B1 and the line A1A3 is 120°, and the angle between the line A2B2 and the line A2A3 is 120°. At this time, the three lines A1C1, A2C2, and A3C3 are perpendicular to the ground. At this time, it is a two-shift and two-rotation freedom mode.

5. The method for reconfiguring a reconfigurable parallel mechanism according to claim 4, characterized in that: The two-translation-one-rotation degree of freedom mode reconstruction method comprises the following steps: The mode switching device drives the rotating shaft 1 and the rotating shaft 2 to rotate respectively, and then drives the support rod 1 and the support rod 2 to rotate respectively, and the electric telescopic rod 1, the electric telescopic rod 2, and the electric telescopic rod 3 are extended or shortened, so that the angle between the line A1B1 and the line A1A2 is 90°, and the angle between the line A2B2 and the line A1A2 is 90°. At this time, the three lines A1C1, A2C2, and A3C3 are perpendicular to the ground. At this time, it is a two-movement and one-rotation freedom mode.

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