A metamorphic operation platform based on face-symmetrical bricard mechanism

Abstract

The application discloses a metamorphic operation platform based on a face-symmetrical Bricard mechanism and belongs to the technical field of machinery. The whole metamorphic operation platform comprises a fixed platform and a moving platform, and the two platforms are connected through left and right moving branch chains. For each moving branch chain, a face-symmetrical Bricard mechanism with equivalent rotation axes in a Bricard mechanism family is used, each moving branch chain has two face-symmetrical Bricard mechanisms, and finally, the metamorphic operation platform with two different motion modes of translation and rotation is obtained through connection design between parts. Therefore, the metamorphic operation platform has changeable operation modes, and has a structure form and a motion reconstruction mechanism obviously different from a metamorphic mechanism obtained by combining connection of conventional typical mechanical joints such as rotating pairs.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of machinery, and relates to a metamorphic operation platform based on a face-symmetrical Bricard mechanism. BACKGROUND

[0002] Metamorphic mechanisms and metamorphic robots can realize different movements and operation modes without changing constituent elements through structural recombination, and thus have significant advantages over traditional mechanisms and robots with single and fixed operation modes in application scenarios such as limiting the structure size of an operation device and operating in a complex unstructured environment where a human being cannot directly enter. Therefore, in recent years, the technology of metamorphic mechanisms and metamorphic robots has gradually become a hot issue in the research of robot technology. As a classical mechanism configuration, the Bricard mechanism has very special and typical movement characteristics due to its special geometric configuration and link structure, and is widely used in the construction of other complex mechanisms, such as space deployable structures and deformation mobile robot mechanisms. SUMMARY

[0003] The application designs a metamorphic operation platform with two different movement modes of translation and rotation by combining and connecting a special face-symmetrical Bricard mechanism unit with equivalent rotation axes in the Bricard mechanism family. The metamorphic operation platform has wide application prospects in the fields of bionic robot movement joint design, unstructured environment exploration special robot, medical surgery robot and the like.

[0004] The metamorphic operation platform based on the face-symmetrical Bricard mechanism comprises a moving platform and a fixed platform, which are arranged in a top-down manner and connected by left and right two movement branch chains.

[0005] The fixed platform and the moving platform are rectangular plate structures with the same size, and columnar joints are designed at the circumferential four corners of the fixed platform and the moving platform. The axes of all the columnar joints are parallel to each other, and the included angle between the axes and the fixed platform and the moving platform is 45°.

[0006] The two movement branch chains have the same structure and are connected to the fixed platform and the moving platform in the same way. Each of the two movement branch chains comprises an upper branch chain and a lower branch chain, and each of the upper branch chain and the lower branch chain comprises two double connecting rods formed by four connecting rods connected in pairs. The upper branch chain and the lower branch chain are connected by a connecting rod.

[0007] In the double connecting rod, columnar joints are designed at the front end and the tail end of each of the two connecting rods, and the torsion angle of the axes of the two end columnar joints is 60 degrees. The tail end joints of the two connecting rods are coaxially connected by a rotating shaft to form a rotating pair A, and the front end joints of the two connecting rods are symmetrical with respect to the axis of the rotating pair A. Two columnar joints are designed at each end of the connecting rod, and the axes of the two end columnar joints are parallel to each other.

[0008] The two double connecting rods in the upper branch chain are connected by a rotating shaft between the two cylindrical joints corresponding to the two ends of the connecting rod and the two joints on one side of the moving platform, respectively, to form a rotating pair, and the other end is connected by a rotating shaft to form a rotating pair with the two joints on one side of the fixed platform, thereby forming a lower face-symmetrical Bricard mechanism.

[0009] The moving platform and the fixed platform on one side are regarded as a platform connecting rod, and the motion input angle of the face-symmetrical Bricard mechanism is the included angle θ between the connecting rod and the connecting rod connected thereto; the motion of the connecting rod relative to the platform connecting rod is a rotating motion around an equivalent virtual rotating shaft, and the equivalent rotation of the moving platform relative to the connecting rod is regarded as a generalized rotating pair. The above overall structure is an equivalent four-bar mechanism connected by four generalized rotating pairs; among them, the fixed platform corresponds to the lower equivalent connecting rod, the fixed platform left side passes through the left side equivalent rotating shaft A, the left side equivalent connecting rod and the left side equivalent rotating shaft B are connected to the upper equivalent connecting rod left side corresponding to the moving platform; the right side of the lower equivalent connecting rod passes through the right side equivalent rotating shaft A, and the right side equivalent connecting rod and the right side equivalent rotating shaft B are connected to the upper equivalent connecting rod right side corresponding to the moving platform.

[0010] In the fully retracted position, the directions of the axes of the rotating shafts in the equivalent four-bar mechanism are parallel to each other, and the whole is a planar four-bar mechanism, and satisfies the relationship: the length of the lower equivalent connecting rod is equal to the length of the upper equivalent connecting rod; the length of the left side equivalent connecting rod is equal to the length of the right side equivalent connecting rod; at this time, the whole is a parallelogram mechanism, and the equivalent motion of the moving platform relative to the fixed platform is a single-degree-of-freedom translational motion, and the four Bricard mechanisms are expanded synchronously; during the gradual expansion of the Bricard mechanism from the fully retracted state, the equivalent four-bar mechanism is always a parallelogram mechanism, and the motion of the moving platform relative to the fixed platform is always a single-degree-of-freedom translational motion.

[0011] When the metamorphic platform is unfolded to the motion bifurcation configuration, the four equivalent connecting rods in the equivalent connecting rod mechanism are collinear at this time, and the four equivalent rotation axes also satisfy the parallel relationship; the upper equivalent connecting rod has both rotation and translation tendencies relative to the lower equivalent connecting rod at this moment; the corresponding motion platform also has both rotation and translation tendencies relative to the fixed platform at this moment. At the motion bifurcation configuration, the switching of different motion modes is realized by controlling different motion inputs; when the motion input θ1 of the left face-symmetrical Bricard mechanism connected with the fixed platform is equal to the motion input θ2 of the right face-symmetrical Bricard mechanism, the equivalent four-bar mechanism is still a parallelogram mechanism, and the motion of the motion platform relative to the fixed platform is still a single-degree-of-freedom translational motion. When the motion input θ1 of the left face-symmetrical Bricard mechanism connected with the fixed platform is not equal to the motion input θ2 of the right face-symmetrical Bricard mechanism, the equivalent mechanism is a crank-rocker mechanism, and the motion of the motion platform relative to the fixed platform is a rotational motion.

[0012] The present application has the advantages of:

[0013] 1. The metamorphic operation platform based on the face-symmetrical Bricard mechanism has variable operation modes, and can realize two different motion modes of unfolding and rotating through a set of mechanisms. The overall degree of freedom of the mechanism is 1 in both the unfolding and rotating motion modes, the motion is reliable, and the control is simple.

[0014] 2. The metamorphic operation platform based on the face-symmetrical Bricard mechanism has a structure and a motion reconstruction mechanism different from those of a traditional metamorphic mechanism based on a typical mechanical joint such as a rotation pair by using the virtual rotation shaft combination of the face-symmetrical Bricard mechanism to obtain the equivalent mechanism configuration. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 It is a whole structure diagram of the metamorphic operation platform based on the face-symmetrical Bricard mechanism.

[0016] Figure 2 It is a structure diagram of the upper and lower connecting platforms of the metamorphic operation platform based on the face-symmetrical Bricard mechanism.

[0017] Figure 3 It is a structure diagram of a single motion branch of the metamorphic operation platform based on the face-symmetrical Bricard mechanism.

[0018] Figure 4 It is a structure diagram of a double connecting rod in a single motion branch.

[0019] Figure 5 It is a structure diagram of a connecting rod in a single motion branch.

[0020] Figure 6 Figure 1 is a schematic diagram of the equivalent motion mode of the face-symmetrical Bricard mechanism in the metamorphic operation platform based on the face-symmetrical Bricard mechanism of the present application.

[0021] Figure 7 Figure 2 is a fully folded state diagram of the face-symmetrical Bricard mechanism as a component unit of the metamorphic operation platform based on the face-symmetrical Bricard mechanism of the present application.

[0022] Figure 8 Figure 3 is a fully unfolded state diagram of the face-symmetrical Bricard mechanism as a component unit of the metamorphic operation platform based on the face-symmetrical Bricard mechanism of the present application.

[0023] Figure 9 Figure 4 is a fully folded state diagram of the metamorphic operation platform based on the face-symmetrical Bricard mechanism of the present application.

[0024] Figure 10 Figure 5 is an equivalent mechanism diagram of the equivalent rotation shafts of the face-symmetrical Bricard mechanism in the fully folded state of the metamorphic operation platform based on the face-symmetrical Bricard mechanism of the present application.

[0025] Figure 11 Figure 6 is a state diagram at the position bifurcation point of the metamorphic operation platform based on the face-symmetrical Bricard mechanism of the present application in different motion modes.

[0026] Figure 12 Figure 7 is an equivalent mechanism diagram of the equivalent rotation shafts of the Bricard mechanism in the position bifurcation point of the metamorphic operation platform based on the face-symmetrical Bricard mechanism of the present application.

[0027] Figure 13 Figure 8 is an unfolding and folding motion state diagram of the metamorphic operation platform based on the face-symmetrical Bricard mechanism of the present application.

[0028] Figure 14 Figure 9 is an equivalent mechanism diagram of the equivalent rotation shafts of the Bricard mechanism in the unfolding and folding motion state of the metamorphic operation platform based on the face-symmetrical Bricard mechanism of the present application.

[0029] Figure 15 Figure 10 is a rotation motion state diagram of the metamorphic operation platform based on the face-symmetrical Bricard mechanism of the present application.

[0030] Figure 16 Figure 11 is an equivalent mechanism diagram of the equivalent rotation shafts of the Bricard mechanism in the rotation motion state of the metamorphic operation platform based on the face-symmetrical Bricard mechanism of the present application.

[0031] In the figure:

[0032] 1 - fixed platform 2 - motion branch chain 3 - motion platform

[0033] 4- virtual rotation axis 5- lower equivalent link 6- upper equivalent link

[0034] 201- upper branch chain 202- lower branch chain 203- equilateral triangle section link

[0035] 204- connecting rod 205- left equivalent rotation pair A 206- left equivalent link

[0036] 207- left equivalent rotation axis B 208- right equivalent rotation axis A 209- right equivalent link 210- right equivalent rotation axis B DETAILED DESCRIPTION

[0037] The application will be further described below in combination with the drawings.

[0038] The metamorphic operation platform based on the face-symmetrical Bricard mechanism mainly consists of four parts, including a fixed platform 1, a moving platform 3 and two moving branch chains 2, as shown in the drawings. Figure 1 Among them, the moving platform 3 and the fixed platform 1 are rectangular plate-shaped structures with the same size, arranged in an up-down manner, and connected by the left and right moving branch chains 2.

[0039] As shown in the drawings, Figure 2 The top surface of the fixed platform 1 is designed with two isosceles triangle section protrusions, two triangle section protrusions a are designed along the front and rear directions and respectively located at the left and right sides of the top surface of the fixed platform 1, and the bottom surfaces of the two isosceles triangle section protrusions a are connected with the bottom surface of the fixed platform 1. The cylindrical joints are designed on the waist positions of the front and rear end surfaces of the two triangle section protrusions a, the cylindrical joints are arranged in the waist direction, coaxially connected with the arc-shaped grooves designed in the waist direction, so that the four joints are respectively located at the four corners of the fixed platform 1, and the axes of the four joints are parallel to each other, and the angles between all joint axes and the top surface of the fixed platform 1 are all α=45°. For the convenience of subsequent description, the two joints on the front side of the fixed platform 1 are respectively joint A and joint B; the two opposite joints on the rear side are respectively joint C and joint D.

[0040] The moving platform 3 has the same structure as the fixed platform 1. Among them, two isosceles triangle section protrusions a are respectively designed on the left and right side edges of the bottom surface of the moving platform 3, and the four joint axes in the moving platform 3 are parallel to the joint axes in the fixed platform 1. For the convenience of subsequent description, the two joints on the front side of the moving platform 3 and above and below joint A and joint B are respectively joint E and joint F; the two joints on the rear side of the moving platform 3 and above and below joint C and joint D are respectively joint G and joint H.

[0041] As shown in the drawings, Figure 3As shown, the two kinematic chains 2 are structurally identical, each of which is composed of an upper chain 201 and a lower chain 202. The upper chain 201 and the lower chain 202 each include two double links formed by four equilateral triangular cross-section links 203 connected to each other in pairs, and the two double links are connected by a connecting link 204. In the upper chain 201, one end of the two double links is connected to the two ends of the connecting link 204 to form a revolute pair, and the other end is connected to one side of the moving platform 3 to form a revolute pair, thereby constituting an upper symmetric Bricard mechanism. In the lower chain 202, one end of the two double links is connected to the two ends of the connecting link 204, and the other end is connected to one side of the fixed platform 1 to form a revolute pair, thereby constituting a lower symmetric Bricard mechanism.

[0042] The above-mentioned link structures and link connection modes are as follows:

[0043] As shown in the figure, Figure 4 the two equilateral triangular cross-section links 203 in one double link are respectively triangular link A and triangular link B, and the ends and the front ends of the two links are designed with cylindrical joints. The joints on the ends are located on one side edge A of the end face, the axis is arranged along the side edge A, and the axis is coaxially connected with the arc-shaped groove opened on the end face, so that the joint axis coincides with the side edge. The front end joints are respectively located on the other two side edges B and side edge C corresponding to the side edge A on the front face, and the axis is arranged along the side edge, and the axis is coaxially connected with the arc-shaped groove opened on the front face, so that the joint axis coincides with the side edge. Since the equilateral triangular cross-section links 203 are used, the front end joint axis and the end joint axis have a torsion angle β = 60°. The joints on the end faces of the two equilateral triangular cross-section links 203 are coaxially connected by a rotating shaft to form a revolute pair A, and the front end joints of the two links are symmetric with respect to the axis of the revolute pair A, thereby constituting a double link. For the convenience of subsequent description, the front end joints of the two equilateral triangular cross-section links 203 in one double link are respectively joint M and joint N.

[0044] As shown in the figure, Figure 5 the connecting link 204 is a rectangular cross-section link, and two cylindrical joints are designed on each end. The two joints on one end are respectively located on the opposite side edges of the end face, and the axes are respectively arranged along the opposite side edges, and are connected with the two arc-shaped grooves opened on the end face, so that the two joint axes coincide with the side edges. The design of the two joints on the other end is the same as the above, and they are symmetrically arranged. For the convenience of subsequent description, the two joints on the same side face of the connecting link 204 are respectively joint I and joint J, and the two joints on the other side face opposite to each other are respectively structure K and structure L.

[0045] In the connecting rod 204 of the above structure, joints I and K are respectively connected to joints M of two double links by rotating shafts to form a revolving pair; joints N of the two double links are respectively connected to joints A and C on one side of the fixed platform 1 by rotating shafts to form a revolving pair, forming a plane-symmetrical Bricard mechanism in the lower middle part of the motion branch 2. Joints J and L in the connecting rod 204 are respectively connected to joints M of the other two double links by rotating shafts to form a revolving pair; joints N of the two double links are respectively connected to joints A and C on one side of the motion platform 3 by rotating shafts to form a revolving pair, forming a plane-symmetrical Bricard mechanism in the upper middle part of the motion branch 2; thus, the connection between the fixed platform 1 and the motion branch 2 on one side of the motion platform 3 is realized. The method of connecting the fixed platform 1 and the motion branch 2 on one side of the motion platform 3 is the same as described above, and finally forms the metamorphic operation platform of the present invention.

[0046] In the metamorphic operating platform of the present invention, the fixed platform 1 is regarded as a platform connection, as shown in FIG. Figure 6 As shown, the motion input angle of a plane-symmetrical Bricard mechanism is set to θ, which is the angle between the connecting rod 204 and the equilateral triangle cross-section connecting rod 203 connected to it; the motion of the connecting rod 204 relative to the platform connecting rod is a rotational motion around the equivalent virtual rotation axis 4, and an equivalent rotation of the motion platform 3 relative to the connecting rod 204. Among them, the position of the virtual rotation axis 4 relative to the platform connecting rod and the connecting rod 204 can be determined by the distance r and the relative angle λ between the platform connecting rod and the connecting rod 204, where r is the vertical distance from the axis of the virtual rotation axis 4 to the platform connecting rod and the connecting rod 204. A plane-symmetrical Bricard mechanism 4 can be realized from a fully folded state to a fully unfolded state through motion, that is, by Figures 7 to 8 The transition of state. Figure 7 In the fully folded state, the triangle rod A and the side A of the triangle rod B in the two double links are aligned, completing the folding of the two double links; the folded two double links are in contact with the platform link and the side of the connecting rod 204 at the same time. Figure 8 In the fully expanded state, the ends of the triangular rod A and the triangular rod B in the two double links are connected to form a straight rod as a whole, which forms a rectangular frame with the platform link and the connecting rod 204.

[0047] As mentioned above, the relative motion between the platform link and the connecting rod 204 in a plane-symmetric Bricard mechanism is equivalent to a rotation around a virtual axis of rotation 4, which can be regarded as a generalized revolute pair. Therefore, the fixed platform 1 and the moving platform 3 in the metamorphic operating platform of the present invention are connected by two left and right motion branches 2 composed of two plane-symmetric Bricard mechanisms, so that the overall structure can be equivalent to a four-bar linkage connected by four generalized revolute pairs. When the plane-symmetric Bricard mechanism is replaced by a generalized revolute pair, the equivalent mechanism diagram of the metamorphic operating platform in this configuration is as follows: Figure 10As shown in FIG. 6, the fixed platform 1 corresponds to the lower equivalent connecting rod 5, the left side of which is connected to the left side of the upper equivalent connecting rod 6 of the moving platform 3 through the left equivalent pivot A2 05, the left equivalent connecting rod 206 and the left equivalent pivot B2 07. The right side of the lower equivalent connecting rod 5 is connected to the right side of the upper equivalent connecting rod 6 of the moving platform 3 through the right equivalent pivot A2 08, the right equivalent connecting rod 209 and the right equivalent pivot B2 10.

[0048] As shown in FIG. 6, the fixed platform 1 corresponds to the lower equivalent connecting rod 5, the left side of which is connected to the left side of the upper equivalent connecting rod 6 of the moving platform 3 through the left equivalent pivot A2 05, the left equivalent connecting rod 206 and the left equivalent pivot B2 07. The right side of the lower equivalent connecting rod 5 is connected to the right side of the upper equivalent connecting rod 6 of the moving platform 3 through the right equivalent pivot A2 08, the right equivalent connecting rod 209 and the right equivalent pivot B2 10. Figure 9 、 Figure 11 、 Figure 13 As shown in FIG. 6, the fixed platform 1 corresponds to the lower equivalent connecting rod 5, the left side of which is connected to the left side of the upper equivalent connecting rod 6 of the moving platform 3 through the left equivalent pivot A2 05, the left equivalent connecting rod 206 and the left equivalent pivot B2 07. The right side of the lower equivalent connecting rod 5 is connected to the right side of the upper equivalent connecting rod 6 of the moving platform 3 through the right equivalent pivot A2 08, the right equivalent connecting rod 209 and the right equivalent pivot B2 10. Figure 10 As shown in FIG. 6, the fixed platform 1 corresponds to the lower equivalent connecting rod 5, the left side of which is connected to the left side of the upper equivalent connecting rod 6 of the moving platform 3 through the left equivalent pivot A2 05, the left equivalent connecting rod 206 and the left equivalent pivot B2 07. The right side of the lower equivalent connecting rod 5 is connected to the right side of the upper equivalent connecting rod 6 of the moving platform 3 through the right equivalent pivot A2 08, the right equivalent connecting rod 209 and the right equivalent pivot B2 10.

[0049] As shown in FIG. 6, the fixed platform 1 corresponds to the lower equivalent connecting rod 5, the left side of which is connected to the left side of the upper equivalent connecting rod 6 of the moving platform 3 through the left equivalent pivot A2 05, the left equivalent connecting rod 206 and the left equivalent pivot B2 07. The right side of the lower equivalent connecting rod 5 is connected to the right side of the upper equivalent connecting rod 6 of the moving platform 3 through the right equivalent pivot A2 08, the right equivalent connecting rod 209 and the right equivalent pivot B2 10. Figure 11 Figure 12 As shown in FIG. 6, the fixed platform 1 corresponds to the lower equivalent connecting rod 5, the left side of which is connected to the left side of the upper equivalent connecting rod 6 of the moving platform 3 through the left equivalent pivot A2 05, the left equivalent connecting rod 206 and the left equivalent pivot B2 07. The right side of the lower equivalent connecting rod 5 is connected to the right side of the upper equivalent connecting rod 6 of the moving platform 3 through the right equivalent pivot A2 08, the right equivalent connecting rod 209 and the right equivalent pivot B2 10. Figure 12 As shown in FIG. 6, the fixed platform 1 corresponds to the lower equivalent connecting rod 5, the left side of which is connected to the left side of the upper equivalent connecting rod 6 of the moving platform 3 through the left equivalent pivot A2 05, the left equivalent connecting rod 206 and the left equivalent pivot B2 07. The right side of the lower equivalent connecting rod 5 is connected to the right side of the upper equivalent connecting rod 6 of the moving platform 3 through the right equivalent pivot A2 08, the right equivalent connecting rod 209 and the right equivalent pivot B2 10.

[0050] Figure 11 As shown in FIG. 6, the fixed platform 1 corresponds to the lower equivalent connecting rod 5, the left side of which is connected to the left side of the upper equivalent connecting rod 6 of the moving platform 3 through the left equivalent pivot A2 05, the left equivalent connecting rod 206 and the left equivalent pivot B2 07. The right side of the lower equivalent connecting rod 5 is connected to the right side of the upper equivalent connecting rod 6 of the moving platform 3 through the right equivalent pivot A2 08, the right equivalent connecting rod 209 and the right equivalent pivot B2 10. Figure 12 Figure 13 As shown in FIG. 6, the fixed platform 1 corresponds to the lower equivalent connecting rod 5, the left side of which is connected to the left side of the upper equivalent connecting rod 6 of the moving platform 3 through the left equivalent pivot A2 05, the left equivalent connecting rod 206 and the left equivalent pivot B2 07. The right side of the lower equivalent connecting rod 5 is connected to the right side of the upper equivalent connecting rod 6 of the moving platform 3 through the right equivalent pivot A2 08, the right equivalent connecting rod 209 and the right equivalent pivot B2 10. Figure 14 Figure 11 ​​​​As shown in the motion bifurcation point, when the control and fixed platform 1 connected with the left side of the symmetrical Bricard mechanism 4 of the motion input θ1 and the right side of the symmetrical Bricard mechanism 4 of the motion input θ2 is equal, that is, θ1=θ2, at this time the equivalent four-bar mechanism corresponding to the cellular operation platform satisfies the above relationship. Therefore Figure 14 The equivalent four-bar mechanism corresponding to the cellular operation platform is still a parallelogram mechanism, and the motion of the moving platform 3 relative to the fixed platform 1 is still a single degree of freedom translational motion, and the cellular operation platform will continue to expand.

[0051] As shown in the motion bifurcation point, when the control and fixed platform 1 connected with the left side of the symmetrical Bricard mechanism 4 of the motion input θ1 and the right side of the symmetrical Bricard mechanism 4 of the motion input θ2 is equal, that is, θ1=θ2, at this time the equivalent four-bar mechanism corresponding to the cellular operation platform satisfies the above relationship. Therefore Figure 15 As shown in the motion bifurcation point, when the control and fixed platform 1 connected with the left side of the symmetrical Bricard mechanism 4 of the motion input θ1 and the right side of the symmetrical Bricard mechanism 4 of the motion input θ2 is equal, that is, θ1=θ2, at this time the equivalent four-bar mechanism corresponding to the cellular operation platform satisfies the above relationship. Therefore Figure 16 As shown in the motion bifurcation point, when the control and fixed platform 1 connected with the left side of the symmetrical Bricard mechanism 4 of the motion input θ1 and the right side of the symmetrical Bricard mechanism 4 of the motion input θ2 is equal, that is, θ1=θ2, at this time the equivalent four-bar mechanism corresponding to the cellular operation platform satisfies the above relationship. Therefore Figure 16 As shown in the motion bifurcation point, when the control and fixed platform 1 connected with the left side of the symmetrical Bricard mechanism 4 of the motion input θ1 and the right side of the symmetrical Bricard mechanism 4 of the motion input θ2 is equal, that is, θ1=θ2, at this time the equivalent four-bar mechanism corresponding to the cellular operation platform satisfies the above relationship. Therefore

Claims

1. A metamorphic operating platform based on a plane-symmetric Bricard mechanism, characterized by: It includes a moving platform and a fixed platform, which are arranged up and down and connected by two moving branches on the left and right respectively; The fixed platform and the moving platform are rectangular plate structures of equal size. Columnar joints are designed at the four circumferential corners of the two platforms. The axes of all columnar joints are parallel to each other, and the angle between the axes and the surfaces of the fixed platform and the moving platform is 45°. The two moving branches have the same structure and are connected in the same way as the fixed platform and the moving platform. Both moving branches consist of an upper branch and a lower branch. Both the upper branch and the lower branch include two double links consisting of four connecting rods connected in pairs, and the upper and lower branches are connected by a connecting rod. In the double connecting rod, both ends and front ends of the two connecting rods are designed with cylindrical joints, and the torsion angle of the axis of the cylindrical joints at both ends is 60 degrees; the end joints of the two connecting rods are coaxially connected by a rotating shaft to form a revolute pair A, and the front end joints of the two connecting rods are symmetrical with respect to the revolute pair A axis; Two cylindrical joints are designed at each end of the connecting rod, and the axes of the cylindrical joints at both ends are parallel to each other; One end of the two double links in the upper branch chain is connected to the two columnar joints corresponding to the two ends of the connecting rod through a rotating shaft to form a revolute pair, and the other end is connected to the two joints on one side of the moving platform through a rotating shaft to form a revolute pair, thereby forming an upper symmetrical Bricard mechanism; one end of the two double links in the lower branch chain is connected to the other two columnar joints installed at the two ends of the connecting rod through a rotating shaft to form a revolute pair, and the other end is connected to the two joints on the one side of the fixed platform to form a revolute pair, thereby forming a lower symmetrical Bricard mechanism; The motion platform and one side of the fixed platform are regarded as a platform link, and the motion input angle of the plane-symmetric Bricard mechanism is the connection angle. The included angle θ between the rod and the connecting rod connected to it; the movement of the connecting rod relative to the platform connecting rod is a rotational movement around the equivalent virtual rotation axis, and the equivalent rotation of the motion platform relative to the connecting rod is regarded as a generalized rotation pair; the metamorphic operating platform is an equivalent four-bar linkage composed of four generalized rotation pairs; among them, the fixed platform corresponds to the lower equivalent link, and the left side of the fixed platform is connected to the left side of the upper equivalent link corresponding to the motion platform through the left equivalent rotation axis A, the left equivalent link and the left equivalent rotation axis B; the right side of the lower equivalent link is connected to the right side of the upper equivalent link corresponding to the motion platform through the right equivalent rotation axis A, the right equivalent link and the right equivalent rotation axis B; In the fully retracted configuration, the directions of the axes of the various rotating shafts in the equivalent four-bar linkage are parallel to each other, forming a planar four-bar linkage as a whole, and satisfying the following relationships: the length of the lower equivalent link is equal to the length of the upper equivalent link; the length of the left equivalent link is equal to the length of the right equivalent link; at this time, the metamorphic operating platform is a parallelogram mechanism, the equivalent motion of the moving platform relative to the fixed platform is a single-degree-of-freedom translational motion, and the four Bricard mechanisms are all deployed synchronously; as the Bricard mechanism gradually deploys from the fully retracted state, the equivalent four-bar linkage remains a parallelogram mechanism, and the motion of the moving platform relative to the fixed platform is always a single-degree-of-freedom translational motion; When the metamorphic platform is unfolded to the motion bifurcation configuration, the four equivalent links in the equivalent linkage mechanism are all collinear, and the four equivalent rotation axes also satisfy the parallel relationship; the upper equivalent link has both rotational and translational motion tendencies relative to the lower equivalent link at this moment; the corresponding motion platform also has two instantaneous motion modes of rotation and movement relative to the fixed platform at this moment; at the motion bifurcation configuration, the switching of its different motion modes is achieved by controlling different motion inputs; when the motion input θ1 of the left-side face-symmetric Bricard mechanism connected to the fixed platform is equal to the motion input θ2 of the right-side face-symmetric Bricard mechanism, the equivalent four-bar mechanism is still a parallelogram mechanism, and the motion of the moving platform relative to the fixed platform is still single-degree-of-freedom translational motion; when the motion input θ1 of the left-side face-symmetric Bricard mechanism connected to the fixed platform is not equal to the motion input θ2 of the right-side face-symmetric Bricard mechanism, the equivalent mechanism is a crank rocker mechanism, and the motion of the moving platform relative to the fixed platform will be rotational motion.

2. A metamorphic operating platform based on a plane-symmetric Bricard mechanism as claimed in claim 1, characterized in that: The columnar joints are respectively designed on the top surface of the fixed platform and the front and rear sides of the moving platform. The isosceles triangle cross-sections designed along the left and right directions are raised at both ends of the isosceles triangle waist, which is coaxially connected to the arc groove opened along the waist direction and coincides with the waist.

3. The metamorphic operating platform based on a plane-symmetric Bricard mechanism as claimed in claim 1, characterized in that: The two connecting rods constituting the double connecting rod are connecting rods with equilateral triangular cross-sections; the joints at the ends of the two are located at a side A of the end face, the axis is arranged along the side A, and is coaxially connected to the arc groove opened on the end face, so that the axis of the joint coincides with the side on which it is located; and the front end joints of the two are respectively located at the other two sides of the front end face outside the side corresponding to side A; and the axis is arranged along the side on which it is located, and is coaxially connected to the arc groove opened on the front end face, so that the axis of the joint coincides with the side on which it is located.

4. The metamorphic operating platform based on a plane-symmetric Bricard mechanism as claimed in claim 1, characterized in that: The columnar joints at both ends of the connecting rod are respectively located at opposite sides of the end face, and the axes are respectively set along the opposite sides and connected to the two arc grooves opened on the end face, and the axes of the two joints coincide with the sides where they are located.

5. The metamorphic operating platform based on a plane-symmetric Bricard mechanism as claimed in claim 1, characterized in that: The plane-symmetrical Bricard mechanism is realized from a fully folded state to a fully unfolded state through movement; when the upper plane-symmetrical Bricard mechanism is in the fully folded state, two of the two double links fit together and are connected to the bottom surface of the motion platform and the connecting rods; when the lower plane-symmetrical Bricard mechanism is in the fully folded state, two of the two double links fit together and are connected to the top surface of the fixed platform and the connecting rods; in the fully unfolded state, two of the two double links of the two plane-symmetrical Bricard mechanisms are connected at opposite ends to form an integral straight rod, which respectively forms a rectangular frame with the sides of the motion platform and the fixed platform and the connecting rods.

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