Metamorphic operation platform based on plane symmetry Bricard mechanism

Abstract

The invention discloses a metamorphic operation platform based on a plane symmetry Bricard mechanism, and belongs to the technical field of machinery. The overall metamorphic operation platform comprises a fixed platform and a moving platform, and the two platforms are connected through a left moving branch chain and a right moving branch chain. Each motion branch chain is composed of a surface symmetry Bricard mechanism with an equivalent rotation axis in a Bricard mechanism family, each motion branch chain is provided with an upper surface symmetry Bricard mechanism and a lower surface symmetry Bricard mechanism, and finally through connection design of all the parts, the metamorphic operation platform with two different motion modes of translation and rotation is obtained. Therefore, the metamorphic operation platform has a variable operation mode, and has a structural form and a motion reconstruction mechanism obviously different from those of a traditional metamorphic mechanism obtained based on typical mechanical joints such as revolute pair combination connection.

Description

Technical Field

[0001] The invention belongs to the field of mechanical technology and relates to a metamorphic operation platform based on a plane-symmetric Bricard mechanism. Background Art

[0002] Metamorphic mechanisms and metamorphic robots can achieve different motion and operation modes through their own structural reorganization without changing the original components. Therefore, they have significant advantages over traditional mechanisms and robots with a single, fixed operation mode in application scenarios such as limiting the structural size of the operating device and operating in complex unstructured environments that are difficult for humans to enter directly. Therefore, in recent years, metamorphic mechanisms and metamorphic robot technology has gradually become a hot topic in robotics research. As a classic mechanism configuration, the Bricard mechanism has very special and typical motion characteristics due to its special geometric configuration and rod structure. It is widely used in mechanism research to construct other complex mechanisms, such as spatially deployable structures, deformable mobile robot mechanisms, etc. Summary of the invention

[0003] The present invention combines and connects a special type of plane-symmetric Bricard mechanism units with equivalent rotation axes in the Bricard mechanism family to design a metamorphic operating platform with two different motion modes: translation and rotation. The metamorphic operating platform has broad application prospects in the fields of bionic robot motion joint design, special robots for unstructured environment detection, and medical surgical robots in the future.

[0004] The invention discloses a metamorphic operating platform based on a plane-symmetric Bricard mechanism, comprising a moving platform and a fixed platform, which are arranged up and down and connected by two left and right moving branches respectively.

[0005] 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, and the axes of all columnar joints are parallel to each other, and the angle between the axes and the fixed platform and the moving platform is 45°.

[0006] 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 are composed of an upper branch and a lower branch; both the upper branch and the lower branch include two double connecting rods composed of four connecting rods connected in pairs; the upper and lower branches are connected by a connecting rod.

[0007] In the above double connecting rod, the ends and front ends of the two connecting rods are designed with column joints, and the torsion angle of the axis of the column joints at both ends is 60 degrees; the end joints of the two connecting rods are coaxially connected through a rotating shaft to form a revolute pair A, and the front end joints of the two are symmetrical with respect to the axis of the revolute pair A. Two column joints are designed at each end of the connecting rod, and the axes of the column joints at both ends are parallel to each other.

[0008] 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 rotating 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 rotating pair, thereby forming an upper face-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 rotating pair, and the other end is connected to the two joints on one side of the fixed platform to form a rotating pair, thereby forming a lower face-symmetrical Bricard mechanism.

[0009] 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 angle θ between the connecting rod and the connecting rod connected to it; the motion of the connecting rod relative to the platform link is a rotational motion 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 above overall structure is an equivalent four-bar linkage formed by connecting four generalized rotation pairs; among which, 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.

[0010] In the fully folded configuration, the directions of the axes of the rotating shafts in the equivalent four-bar linkage are parallel to each other, and the whole is a planar four-bar linkage, and the following relationships are satisfied: 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 whole 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 folded state, the equivalent four-bar linkage 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 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 rotation and translation 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 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 a single-degree-of-freedom translation 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.

[0012] The advantages of the present invention are:

[0013] 1. The present invention provides a metamorphic operating platform based on a plane-symmetric Bricard mechanism with a changeable operating mode, and can realize two different motion modes of extension and retraction and rotation through a set of mechanisms. In addition, the overall degree of freedom of the mechanism is 1 in both the extension and retraction and rotation modes, and the motion is reliable and the control is simple.

[0014] 2. The metamorphic operating platform based on the plane-symmetric Bricard mechanism of the present invention obtains its equivalent mechanism configuration by utilizing the virtual axis combination of the plane-symmetric Bricard mechanism, and has a structural form and motion reconstruction mechanism that are significantly different from the traditional metamorphic mechanism obtained by combining typical mechanical joints such as revolute pairs. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is the overall structural diagram of the metamorphic operating platform based on the plane-symmetric Bricard mechanism of the present invention.

[0016] Figure 2 It is a structural diagram of the upper and lower connecting platforms of the metamorphic operating platform based on the plane-symmetric Bricard mechanism of the present invention.

[0017] Figure 3 This is a structural diagram of a single moving branch of the metamorphic operating platform based on the plane-symmetric Bricard mechanism of the present invention.

[0018] Figure 4 This is the double-link structure diagram in a single kinematic branch chain.

[0019] Figure 5 This is the structural diagram of the connecting rod in a single kinematic branch chain.

[0020] Figure 6 It is a schematic diagram of the equivalent motion mode of the plane-symmetric Bricard mechanism in the metamorphic operating platform based on the plane-symmetric Bricard mechanism of the present invention.

[0021] Figure 7 This is a diagram of the fully collapsed state of the plane-symmetric Bricard mechanism, which is a component unit of the metamorphic operating platform based on the plane-symmetric Bricard mechanism of the present invention.

[0022] Figure 8 The diagram is a fully expanded state diagram of a plane-symmetric Bricard mechanism, which is a component unit of the metamorphic operating platform based on the plane-symmetric Bricard mechanism of the present invention.

[0023] Fig. 9 This is a diagram of the fully folded state of the metamorphic operating platform based on the plane-symmetric Bricard mechanism of the present invention.

[0024] Fig.10 It is an equivalent mechanism diagram of the equivalent rotating shaft of the plane-symmetric Bricard mechanism when the metamorphic operating platform based on the plane-symmetric Bricard mechanism of the present invention is in a fully folded state.

[0025] Fig.11 The present invention is a state diagram of the metamorphic operating platform based on the plane-symmetric Bricard mechanism at the configuration bifurcation point in different motion modes.

[0026] Fig.12 The present invention is an equivalent mechanism diagram of the equivalent rotating shaft of the Bricard mechanism when the metamorphic operating platform based on the plane-symmetric Bricard mechanism is at a configuration bifurcation point.

[0027] Fig.13 The present invention is a motion state diagram of the metamorphic operating platform based on the plane-symmetric Bricard mechanism.

[0028] Fig.14 It is an equivalent mechanism diagram of the equivalent rotating shaft of the Bricard mechanism in the expansion and contraction state of the metamorphic operating platform based on the plane-symmetric Bricard mechanism of the present invention.

[0029] Fig.15 The figure is a rotational motion state diagram of the metamorphic operating platform based on the plane-symmetric Bricard mechanism of the present invention.

[0030] Fig.16 It is an equivalent mechanism diagram of the equivalent rotating shaft of the Bricard mechanism under the rotational motion state of the metamorphic operating platform based on the plane-symmetric Bricard mechanism of the present invention.

[0031] In the figure:

[0032] 1-Fixed platform 2-Moving branch chain 3-Moving platform

[0033] 4-virtual shaft 5-lower equivalent connecting rod 6-upper equivalent connecting rod

[0034] 201-upper branch chain 202-lower branch chain 203-equilateral triangle cross-section connecting rod

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

[0036] 207- Left equivalent shaft B 208- Right equivalent shaft A 209- Right equivalent connecting rod 210-right equivalent axis B DETAILED DESCRIPTION

[0037] The present invention will be further described below in conjunction with the accompanying drawings.

[0038] The present invention discloses a metamorphic operation platform based on a plane-symmetric Bricard mechanism, which is mainly composed of four parts, including a fixed platform 1, a moving platform 3 and two moving branches 2. Figure 1 As shown, the moving platform 3 and the fixed platform 1 are rectangular plate structures of equal size, arranged up and down, and connected by two left and right moving branches 2.

[0039] like Figure 2 As shown, the top surface of the fixed platform 1 is designed with two isosceles triangular cross-section protrusions. The two triangular cross-section protrusions a are designed along the front-to-back direction and are 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 triangular cross-section protrusions a are connected to the bottom surface of the fixed platform 1. Cylindrical joints are designed at the waist position on the front and rear end surfaces of the two triangular cross-section protrusions a. The cylindrical joints are axially arranged along the waist direction and are coaxially connected to the arc groove designed along 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 the axes of all joints and the top surface of the fixed platform 1 are α=45°. For the convenience of subsequent explanation, the two joints on the front side of the fixed platform 1 are respectively joint A and joint B; the two joints opposite to each other on the rear side are respectively joint C and joint D.

[0040] The motion platform 3 has the same structural form as the fixed platform 1. Among them, two isosceles triangle cross-section protrusions a are respectively designed at the left and right sides of the bottom surface of the motion platform 3, and the four joint axes in the motion platform 3 are parallel to the joint axes in the fixed platform 1. For the convenience of subsequent description, the joints located on the front side of the motion platform 3 opposite to joint A and joint B are respectively joint E and joint F; the two joints located on the rear side of the motion platform 3 opposite to joint C and joint D are respectively joint G and joint H.

[0041] like Figure 3As shown, the two motion branches 2 have the same structure, and are both composed of an upper branch chain 201 and a lower branch chain 202. The upper branch chain 201 and the lower branch chain 202 both include two double links composed of four equilateral triangle cross-section links 203 connected in pairs, and the two are connected by a connecting rod 204. Among them, one end of the two double links in the upper branch chain 201 is connected to the two ends of the connecting rod 204 to form a revolute pair, and the other end is connected to one side of the motion platform 3 to form a revolute pair, forming an upper symmetrical Bricard mechanism; one end of the two double links in the lower branch chain 202 is connected to the two ends of the connecting rod 204, and the other end is connected to one side of the fixed platform 1 to form a revolute pair, forming a lower symmetrical Bricard mechanism.

[0042] The above-mentioned connecting rod structures and connecting methods are specifically as follows:

[0043] like Figure 4 As shown, the two equilateral triangle cross-section connecting rods 203 in a double connecting rod are triangular rod A and triangular rod B, and both ends and front ends are designed with cylindrical joints; and the joints on the ends of the two are located at a side A of the end face of the end, and the axis is set along the side A and coaxially connected with the arc groove opened on the end face of the end, so that the axis of the joint coincides with the side where it is located; and the front end joints of the two are respectively located at the other two sides B and side C outside the side corresponding to side A on the front end face; and the axis is set along the side where it is located, and coaxially connected with the arc groove opened on the front end face, so that the axis of the joint coincides with the side where it is located. Due to the use of the equilateral triangle cross-section connecting rod 203, there is a torsion angle β=60° between the axis of the front end joint and the axis of the end joint. The joints on the end surfaces of the two equilateral triangular cross-section connecting rods 203 of the above structure are coaxially connected through a rotating shaft to form a revolving pair A, and the front end joints of the two are symmetrical with respect to the axis of the revolving pair A to form a double connecting rod; for the convenience of subsequent explanation, the front end joints of the two equilateral triangular cross-section connecting rods 203 in a double connecting rod are respectively joints M and joints N.

[0044] like Figure 5 As shown, the connecting rod 5 is a connecting rod with a rectangular cross section, and two cylindrical joints are designed at each end. The two joints on one end are respectively located at opposite sides of the end face, and the axes are respectively arranged along the opposite sides and connected to the two arc grooves opened on the end face, so that the axes of the two joints coincide with the sides where they are located. The design method 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 end face of the connecting rod 204 are respectively joint I and joint J, and the two joints on the other side end face opposite to the two are respectively structure K and structure L.

[0045] The joints I and K in the connecting rod 204 of the above structure are respectively connected to the joints M of the two double connecting rods by a rotating shaft to form a revolving pair; the joints N of the two double connecting rods are respectively connected to the joints A and C on one side of the fixed platform 1 by a rotating shaft to form a revolving pair, forming a plane-symmetrical Bricard mechanism in the lower middle of the motion branch chain 2. The joints J and L in the connecting rod 204 are respectively connected to the joints M of the other two double connecting rods by a rotating shaft to form a revolving pair, and the joints N of the two double connecting rods are respectively connected to the joints A and C on one side of the motion platform 3 by a rotating shaft to form a revolving pair, forming a plane-symmetrical Bricard mechanism in the upper middle of the motion branch chain 2; thus, the connection between the fixed platform 1 and the motion branch chain 2 on one side of the motion platform 3 is realized. The method for connecting the fixed platform 1 and the motion branch chain 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 operation platform of the present invention, the fixed platform 1 is regarded as a platform connection, then Figure 6 As shown, the motion input angle of a plane-symmetric Bricard mechanism is set to θ, that is, the angle between the connecting rod 204 and the equilateral triangle cross-section connecting rod 203 connected thereto; 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 the 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-symmetric Bricard mechanism 4 can be realized from a fully folded state to a fully unfolded state through motion, that is, by Figure 7 to Figure 8 The transition of state. Figure 7 In the fully folded state, the triangular rod A in the two double links fits in the plane where the side A in the triangular rod B is located, 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 connecting rods are connected to form a straight rod as a whole, which forms a rectangular frame with the platform connecting rod and the connecting rod 204.

[0047] As mentioned above, the relative motion between the platform connecting rod and the connecting rod 204 in a plane-symmetric Bricard mechanism can be equivalent to a rotation around a virtual rotation axis 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: Fig.10As shown. Among them, the fixed platform 1 corresponds to the lower equivalent link 5, and its left side is connected to the left side of the upper equivalent link 6 corresponding to the moving platform 3 through the left equivalent rotation axis A205, the left equivalent link 206 and the left equivalent rotation axis B207. The right side of the lower equivalent link 5 is connected to the right side of the upper equivalent link 6 corresponding to the moving platform 3 through the right equivalent rotation axis A208, the right equivalent link 209 and the right equivalent rotation axis B210.

[0048] like Fig. 9 , Fig.11 , Fig.13 As shown, the process of the metamorphic operating platform of the present invention from the complete folding to the unfolding of the four face-symmetrical Bricard mechanisms 4 is shown. In the completely folded configuration, the directions of the rotation axes of the equivalent four-bar linkage are parallel to each other. The mechanism is a planar four-bar linkage and satisfies the following relationship: the length of the lower equivalent link 5 is equal to the length of the upper equivalent link 6; the length of the left equivalent link 206 is equal to the length of the right equivalent link 209. At this time, the mechanism is a parallelogram mechanism, and the equivalent motion of the moving platform 3 relative to the fixed platform 1 is a single-degree-of-freedom translational motion, and the four Bricard mechanisms in the metamorphic operating platform are all unfolded synchronously. As the Bricard mechanism 4 gradually unfolds from the completely folded state, the metamorphic platform as a whole also gradually unfolds. During the unfolding process of the metamorphic platform, Fig.10 The positions of the four equivalent rotating axes and the lengths of the four equivalent connecting rods change with the movement of the mechanism, but they always satisfy the above relationship during the movement. Therefore, the equivalent four-bar linkage is always a parallelogram mechanism, and the movement of the moving platform 3 relative to the fixed platform 1 is always a single-degree-of-freedom translational motion.

[0049] When the metamorphic platform is expanded to Fig.11 When the motion bifurcation configuration is shown, the equivalent mechanism diagram corresponding to the metamorphic operation platform is as follows: Fig.12 As shown. Fig.12 It can be seen that the four equivalent links are all collinear, and the four equivalent rotation axes also satisfy the parallel relationship. At this time, the equivalent four-bar linkage is in a special singular configuration, and the number of degrees of freedom of the mechanism will increase to 2. The upper equivalent link 6 has both rotation and translation tendencies relative to the lower equivalent link 5 at this moment. The corresponding motion platform 3 also has two instantaneous motion modes of rotation and movement relative to the fixed platform 1 at this moment.

[0050] exist Fig.11 and Fig.12 At the motion bifurcation configuration shown in FIG, the switching of different motion modes can be achieved by controlling different motion inputs of the metamorphic platform. Fig.13 and Fig.14 As shown, in the metamorphic platform Fig.11At the motion bifurcation point shown, when the motion input θ1 of the left-side symmetric Bricard mechanism 4 connected to the fixed platform 1 is equal to the motion input θ2 of the right-side symmetric Bricard mechanism 4, that is, θ1=θ2, the equivalent four-bar mechanism corresponding to the metamorphic operating platform satisfies the above relationship. Fig.14 The corresponding equivalent four-bar mechanism is still a parallelogram mechanism, the movement of the moving platform 3 relative to the fixed platform 1 is still a single-degree-of-freedom translational motion, and the metamorphic operating platform will continue to unfold.

[0051] like Fig.15 As shown in the figure, when the motion input θ1 of the left-side symmetric Bricard mechanism connected to the fixed platform 1 and the motion input θ2 of the right-side symmetric Bricard mechanism 4 are not equal at the motion bifurcation point of the metamorphic operating platform, that is, θ1≠θ2, the equivalent mechanism diagram corresponding to the metamorphic platform is as follows: Fig.16 As shown. Fig.16 It can be seen that the equivalent mechanism corresponding to the metamorphic platform is a crank rocker mechanism, and the movement of the moving platform 3 relative to the fixed platform 1 will be a rotational movement.

Claims

1. A metamorphic operation platform based on a face-symmetric Bricard mechanism, Features: It includes a moving platform and a fixed platform, which are arranged up and down and connected by two left and right moving branches 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, and 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; the two moving branches are composed of an upper branch and a lower branch; the upper branch and the lower branch each include two double connecting rods composed of four connecting rods connected in pairs, and the upper and lower branches are connected by a connecting rod; In the double connecting rod, the ends and front ends of the two connecting rods are designed with column joints, and the torsion angle of the axis of the column joints at both ends is 60 degrees; the end joints of the two connecting rods are coaxially connected through a rotating shaft to form a revolute pair A, and the front end joints of the two are symmetrical with respect to the revolute pair A axis; Two columnar joints are designed at each end of the connecting rod, and the axes of the columnar joints at both ends are parallel to each other; One end of the two double connecting rods in the upper branch chain is respectively connected to the two columnar joints corresponding to the two ends of the connecting rod through a rotating shaft to form a rotating pair, and the other end is respectively connected to the two joints on one side of the moving platform through a rotating shaft to form a rotating pair, thereby forming an upper symmetrical Bricard mechanism; one end of the two double connecting rods in the lower branch chain is respectively connected to the other two columnar joints installed at the two ends of the connecting rod through a rotating shaft to form a rotating pair, and the other end is respectively connected to the two joints on one side of the fixed platform to form a rotating pair, forming a lower symmetrical Bricard mechanism; The motion platform and one side of the fixed platform are regarded as a platform connecting rod, and the motion input angle of the plane-symmetric Bricard mechanism is the angle θ between the connecting rod and the connecting rod connected to it; the motion of the connecting rod relative to the platform connecting rod is a rotational motion around the equivalent virtual rotation axis, and the equivalent rotation of the motion platform relative to the connecting rod is regarded as a generalized revolute pair; then the above overall structure is an equivalent four-bar linkage formed by connecting four generalized revolute pairs; wherein, the fixed platform corresponds to the lower equivalent connecting rod, and the left side of the fixed platform is connected to the left side of the upper equivalent connecting rod corresponding to the motion platform through the left equivalent rotation axis A, the left equivalent connecting rod and the left equivalent rotation axis B; the right side of the lower equivalent connecting rod is connected to the right side of the upper equivalent connecting rod corresponding to the motion platform through the right equivalent rotation axis A, the right equivalent connecting rod and the right equivalent rotation axis B; In the fully folded configuration, the directions of the axes of the rotating shafts in the equivalent four-bar linkage are parallel to each other, and the whole is a planar four-bar linkage, and the following relations are satisfied: 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 whole is a parallelogram mechanism, and the equivalent motion of the moving platform relative to the fixed platform is a single-degree-of-freedom translation motion, and the four Bricard mechanisms are all deployed synchronously; as the Bricard mechanism gradually deploys from the fully folded state, the equivalent four-bar linkage is always a parallelogram mechanism, and the motion of the moving platform relative to the fixed platform is always a single-degree-of-freedom translation 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 rotation and translation 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 different motion modes is achieved by controlling different motion inputs; when the motion input θ of the left side symmetric Bricard mechanism connected to the fixed platform is controlled 1 Motion input θ of the Bricard mechanism symmetrical to the right side 2 = equal, at this time the equivalent four-bar mechanism is still a parallelogram mechanism, and the motion of the moving platform relative to the fixed platform is still a single-degree-of-freedom translation motion; when the motion input θ of the left-side symmetrical Bricard mechanism connected to the fixed platform is controlled 1 Motion input θ of the Bricard mechanism symmetrical to the right side 2 They are not equal. In this case, the equivalent mechanism is a crank-rocker mechanism, and the movement 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, Features: 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 section protrusions at both ends designed along the left and right directions are coaxially connected to the arc grooves opened along the waist direction and coincide with the waist.

3. A metamorphic operating platform based on a plane-symmetric Bricard mechanism as claimed in claim 1, Features: The two connecting rods constituting the double connecting rod are equilateral triangular cross-section connecting rods; 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 the 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. A metamorphic operating platform based on a plane-symmetric Bricard mechanism as claimed in claim 1, Features: The columnar joints at both ends of the connecting rod are respectively located at opposite sides of the end surface, and the axes are respectively arranged along the opposite sides and connected with two arc grooves opened on the end surface, and the axes of the two joints coincide with the sides where they are located.

5. A metamorphosis operation platform based on a plane-symmetric Bricard mechanism as claimed in claim 1, Features: The plane-symmetric Bricard mechanism is realized from a fully folded state to a fully unfolded state through movement; when the upper plane-symmetric Bricard mechanism is in a fully folded state, two of the two double links fit each other and are connected to the bottom surface of the motion platform and the connecting rods at the same time; when the lower plane-symmetric Bricard mechanism is in a fully folded state, two of the two double links fit each other and are connected to the top surface of the fixed platform and the connecting rods at the same time; in a fully unfolded state, two of the two double links of the two plane-symmetric 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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