Five-degree-of-freedom parallel machine tool with spiral state constraint passive branch

Abstract

The application provides a five-degree-of-freedom parallel machine tool with a screw state constraint passive branch, and relates to the technical field of parallel machine tools, which comprises a rack, a fixed platform, a movable platform, five active unconstrained branches and one passive constrained branch connecting the fixed platform and the movable platform, and an electric spindle, wherein the active unconstrained branches are all UPS branches composed of a hook joint, a moving pair and a spherical joint, and the passive constrained branch is a UPU branch composed of two hook joints and one moving pair; the parallel machine tool in the application generates independent screw state constraint by arranging the sixth branch as a passive constrained branch and vertically arranging the inner rotating pair of the second hook joint and the outer rotating pair of the third hook joint, so that the branch generates independent screw state constraint; the independent screw state provided by the passive constrained branch acts on the movable platform, so that the electric spindle has five-degree-of-freedom motion of two rotations, two movements and one independent screw motion.

Description

Technical Field

[0001] This invention relates to the field of parallel machine tool technology, and more specifically to a five-degree-of-freedom parallel machine tool with a helical-state constrained passive branch. Background Technology

[0002] In the field of industrial robots, the use of parallel mechanisms is increasing. Among them, parallel mechanisms based on specific configurations and possessing excellent motion and mechanical performance, such as the Stewart platform, Exechon, and Sprint Z3, are recognized as the benchmarks of high-end technical equipment in this field.

[0003] Five-degree-of-freedom (DOF) parallel machine tools, as an important component of low-DOF parallel mechanisms, are widely used in the machining and manufacturing of high-end equipment, especially in the machining of complex curved surfaces, where they possess unique advantages. The end effector of a five-DOF parallel machine tool typically exhibits a motion pattern of three rotations and two translations or three translations and two rotations, with the branches constrained by forces or couples. Currently, five-DOF parallel machine tools containing independent helical constraints are very rare. Independent helical constraints offer better resistance to deformation than single constraint forces or moments, achieving a coupled and superimposed effect of constraint forces and moments, thus giving the machine tool greater rigidity and load-bearing capacity. Some five-DOF parallel machine tools with independent helical constraints often have helical pairs added to their motion branches, severely impacting the mechanism's performance and resulting in complex structures and high manufacturing difficulty.

[0004] In these situations, the lack of effective parallel machine tools will have a wide-ranging impact. Therefore, it is necessary to propose a new parallel machine tool structure in order to solve the above-mentioned defects. Summary of the Invention

[0005] To address the shortcomings of the prior art, the present invention aims to provide a five-degree-of-freedom parallel machine tool with a helical constraint passive branch. This machine tool utilizes a combination of prismatic joints, Hooke joints, and ball joints to achieve five degrees of freedom motion at its end point: two rotations, two translations, and one independent helical motion. The parallel machine tool of this invention omits helical joints, simplifying the overall structure and reducing the difficulty of machining and assembly. The addition of a passive branch further enhances the machine tool's load-bearing capacity, providing advantages such as a large working space and easy control. Furthermore, the use of the passive branch effectively eliminates the self-motion of the parallel machine tool.

[0006] This invention provides a five-degree-of-freedom parallel machine tool with a helical constraint passive branch, comprising: a frame, a fixed platform, a moving platform, an electric spindle, a first branch, a second branch, a third branch, a fourth branch, a fifth branch, and a sixth branch; The first, second, third, fourth, and fifth branches have their first ends evenly distributed on the fixed platform and their second ends evenly distributed on the moving platform. The first end of the sixth branch is installed in the center of the fixed platform and its second end is installed in the center of the first side of the moving platform. An electric spindle is installed in the center of the second side of the moving platform. The fixed platform is installed at the first end of the frame. The first branch, the second branch, the third branch, the fourth branch, and the fifth branch, as active unconstrained branches, each include a prismatic joint, a first Hooke's joint, and a ball joint. The first Hooke's joint connects the fixed platform and the first end of the prismatic joint. The second end of the prismatic joint is connected to the ball joint, and the ball joint is connected to the moving platform. The sixth branch, as a passive constraint branch, includes the second Hooke hinge, the passive telescopic rod, and the third Hooke hinge. The second Hooke hinge connects both the moving platform and the first end of the passive telescopic rod, while the third Hooke hinge connects both the second end of the passive telescopic rod and the fixed platform. The constraint screw of the sixth branch... Its pitch h6 expression is: ; ; In the formula, α represents the rotation angle of the inner revolute joint of the third Hooke's hinge about the outer revolute joint of the third Hooke's hinge, β represents the rotation angle of the passive telescopic rod about the inner revolute joint of the third Hooke's hinge, λ represents the rotation angle of the passive telescopic rod about the inner revolute joint of the second Hooke's hinge, L represents the length of the passive telescopic rod, and c α =cos(α), s α =sin(α), c β =cos(β), s β =sin(β), c λ =cos(λ), s λ =sin(λ).

[0007] By vertically positioning the second and third Hooke hinge revolute joints of the sixth branch, the constraint screw of the passive constraint branch is made more flexible. The electric spindle has a finite and non-zero pitch within its workspace, forming an independent helical constraint. Based on the independent helical constraint provided by the passive constraint branch, the electric spindle has five degrees of freedom of motion, including two rotations, two translations, and one independent helical motion.

[0008] Preferably, the first Hooke hinge includes an outer revolute joint and an inner revolute joint. The outer revolute joint is connected to the fixed platform, the inner revolute joint is connected to the first end of the prismatic joint, the second end of the prismatic joint is connected to a ball joint, and the ball joint is simultaneously connected to the moving platform.

[0009] Preferably, the second Hooke hinge includes an outer rotating joint and an inner rotating joint. The outer rotating joint is installed in the center of the moving platform, and the inner rotating joint is connected to the first end of the passive telescopic rod. The axis of the inner rotating joint is perpendicular to the axis of the passive telescopic rod.

[0010] Preferably, the third Hooke hinge includes an outer rotating joint and an inner rotating joint, the second end of the passive telescopic rod is connected to the inner rotating joint, and the outer rotating joint is connected to the center position of the fixed platform.

[0011] Preferably, the motion screw of the moving platform of the parallel machine tool satisfies: ; Where $1 and $2 represent rotational motion, $4 and $5 represent translational motion, $3 represents independent helical motion, and c α =cos(α),s α =sin(α), c β =cos(β), s β =sin(β), c λ =cos(λ), s λ =sin(λ), t α =tan(α).

[0012] Preferably, the axis of the first Hooke's hinge external revolute joint is aligned with the opposite side of the fixed platform.

[0013] Preferably, the axis of the revolute joint within the first Hooke's joint is perpendicular to the axis of the prismatic joint.

[0014] Preferably, the axis of the second Hooke's hinge external revolute joint is flush with the edge of the moving platform.

[0015] Furthermore, preferably, the axis of the passive telescopic rod is perpendicular to the axis of the inner rotating joint of the third Hooke's hinge.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention realizes a new five-degree-of-freedom parallel machine tool end effector motion form, which includes two rotations, two translations, and one helical motion at the end. 2. The UPU constraint branch of the present invention provides a helical constraint for the entire machine tool. The helical constraint can simultaneously resist internal forces in the form of force and couple in the mechanism, thereby improving the stiffness of the parallel machine tool. 3. The present invention adopts a six-branch structure with five active unconstrained branches and one passive constrained branch, which improves the load-bearing capacity of the parallel mechanism. The use of the passive constrained branch and its installation in the central position of the mechanism distributes the load, reduces the burden on each active branch, and reduces the deformation and driving torque of the active unconstrained branch. This helps to improve the overall accuracy of the parallel machine tool and to make the drive more compact and efficient. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of the five-degree-of-freedom parallel machine tool with helical state constraint passive branch of the present invention; Figure 2 This is a schematic diagram of the parallel mechanism structure of the five-degree-of-freedom parallel machine tool with helical-state constrained passive branches according to the present invention; Figure 3 This is a schematic diagram of the active unconstrained branch of the five-degree-of-freedom parallel machine tool with helical state constrained passive branch according to the present invention. Figure 4 This is a schematic diagram of the passive constraint branch of the five-degree-of-freedom parallel machine tool with helical constraint passive branch according to the present invention; Figure 5 This is a schematic diagram illustrating the parameter annotations of the passive constraint branch of the five-degree-of-freedom parallel machine tool with helical constraint passive branch according to the present invention.

[0018] Key reference numerals: 1. Frame; 2. Fixed platform; 3. Moving platform; 4. Electric spindle; 5. Sliding pair; 6. Servo motor; 7. First Hooke joint; 8. Ball joint; 9. Second Hooke joint; 10. Passive telescopic rod; 11. External revolute joint of the first Hooke joint; 12. Internal revolute joint of the first Hooke joint; 13. External revolute joint of the second Hooke joint; 14. Internal revolute joint of the second Hooke joint; 15. Third Hooke joint; 16. External revolute joint of the third Hooke joint; 17. Internal revolute joint of the third Hooke joint; 21. First branch; 22. Second branch; 23. Third branch; 24. Fourth branch; 25. Fifth branch; 26. Sixth branch. Detailed Implementation

[0019] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0020] This invention provides a five-degree-of-freedom parallel machine tool with helical-state constrained passive branches, such as... Figures 1-4As shown, it includes: a frame 1, a fixed platform 2, a moving platform 3, an electric spindle 4, a servo motor 6, a first branch 21, a second branch 22, a third branch 23, a fourth branch 24, a fifth branch 25, and a sixth branch 26. The first ends of the first branches 21, 22, 33, 44, and 55 are evenly distributed along the edge of the fixed platform 2, and the second ends are evenly distributed along the edge of the moving platform 3. The first end of the sixth branch 26 is installed in the center of the fixed platform 2, and the second end is installed in the center of the first side of the moving platform 3. The electric spindle 4 is installed in the center of the second side of the moving platform 3. The fixed platform 2 is installed at the first end of the frame 1.

[0021] The first branch 21, the second branch 22, the third branch 23, the fourth branch 24, and the fifth branch 25 are all active unconstrained branch structures with the same structure, each including a prismatic joint 5, a first Hooke hinge 7, and a ball hinge 8. The first Hooke hinge 7 connects the fixed platform 2 and the first end of the prismatic joint 5. The second end of the prismatic joint 5 is connected to the ball hinge 8, and the ball hinge 8 is connected to the moving platform 3.

[0022] The sixth branch 26, as a passive constraint branch, includes a second Hooke hinge 9, a passive telescopic rod 10, and a third Hooke hinge 15. The second Hooke hinge 9 connects both the moving platform 3 and the first end of the passive telescopic rod 10, while the third Hooke hinge 15 connects both the second end of the passive telescopic rod 10 and the fixed platform 2. The constraint screw of the sixth branch 26... Its pitch h6 expression is: ; ; In the formula, α represents the rotation angle of the inner revolute joint 17 of the third Hooke's hinge about the outer revolute joint 16 of the third Hooke's hinge, β represents the rotation angle of the passive telescopic rod 10 about the inner revolute joint 17 of the third Hooke's hinge, λ represents the rotation angle of the passive telescopic rod 10 about the inner revolute joint 14 of the second Hooke's hinge, L represents the length of the passive telescopic rod 10, and c α =cos(α), s α =sin(α), c β =cos(β), s β =sin(β), c λ =cos(λ), s λ =sin(λ).

[0023] By vertically aligning the second Hooke hinge inner revolute joint 14 and the third Hooke hinge inner revolute joint 17 of the sixth branch 26, the constraint screw of the passive constraint branch is made... The electric spindle 4 has a finite and non-zero pitch within its workspace, forming an independent helical constraint. Based on the independent helical constraint provided by the passive constraint branch, the electric spindle 4 has five degrees of freedom of motion, including two rotations, two translations, and one independent helical motion.

[0024] The first Hooke hinge 7 includes an outer revolute joint 11 and an inner revolute joint 12. The outer revolute joint 11 is connected to the fixed platform 2, and the inner revolute joint 12 is connected to the first end of the sliding joint 5. The second end of the sliding joint 5 is connected to a ball joint 8, which is also connected to the moving platform 3.

[0025] The second Hooke hinge 9 includes a second Hooke hinge outer rotating joint 13 and a second Hooke hinge inner rotating joint 14. The second Hooke hinge outer rotating joint 13 is installed in the center of the moving platform 3. The second Hooke hinge inner rotating joint 14 is connected to the first end of the passive telescopic rod 10, and the axis of the second Hooke hinge inner rotating joint 14 is perpendicular to the axis of the passive telescopic rod 10.

[0026] The third Hooke hinge 15 includes an outer rotating joint 16 and an inner rotating joint 17. The second end of the passive telescopic rod 10 is connected to the inner rotating joint 17 of the third Hooke hinge, and the outer rotating joint 16 of the third Hooke hinge is connected to the center position of the fixed platform 2.

[0027] The motion screw of the moving platform 3 of the parallel machine tool satisfies: ; Where $1 and $2 represent rotational motion, $4 and $5 represent translational motion, and $3 represents independent helical motion. That is, the end-effector motion of this invention consists of two rotations, two translations, and one independent helical motion. α =cos(α), s α =sin(α), c β =cos(β), s β =sin(β), c λ =cos(λ), s λ =sin(λ), t α =tan(α).

[0028] The axis of the first Hooke hinge outer revolute joint 11 is flush with the opposite side of the fixed platform 2. The axis of the first Hooke hinge inner revolute joint 12 is perpendicular to the axis of the prismatic joint 5. The axis of the second Hooke hinge outer revolute joint 13 is flush with the side of the moving platform 3. The axis of the passive telescopic rod 10 is perpendicular to the axis of the third Hooke hinge inner revolute joint 17.

[0029] Specifically, such as Figure 1 and Figure 2As shown, the present invention includes: a frame 1, a fixed platform 2, a moving platform 3, an electric spindle 4, a first branch 21, a second branch 22, a third branch 23, a fourth branch 24, a fifth branch 25, and a sixth branch 26. The first ends of the first branch 21, the second branch 22, the third branch 23, the fourth branch 24, and the fifth branch 25 are evenly distributed on the edge of the fixed platform 2, and the second ends are evenly distributed on the edge of the moving platform 3. The first end of the sixth branch 26 is installed in the center of the fixed platform 2, and the second end is installed in the center of the first side of the moving platform 3. The electric spindle 4 is installed in the center of the second side of the moving platform 3. The fixed platform 2 is installed at the first end of the frame 1.

[0030] The first branch 21, the second branch 22, the third branch 23, the fourth branch 24, and the fifth branch 25 are all active unconstrained branch structures with the same structure, each including a prismatic joint 5, a first Hooke's joint 7, and a ball joint 8. The first Hooke's joint 7 connects the fixed platform 2 and the first end of the prismatic joint 5. The second end of the prismatic joint 5 is connected to the ball joint 8, and the ball joint 8 is connected to the moving platform 3.

[0031] The sixth branch 26, as a passive constraint branch, includes the second Hooke hinge 9, the passive telescopic rod 10, and the third Hooke hinge 15. The second Hooke hinge 9 connects the fixed platform 2 and the first end of the passive telescopic rod 10, and the third Hooke hinge 15 connects the second end of the passive telescopic rod 10 and the moving platform 3.

[0032] Furthermore, such as Figure 1 and Figure 2 As shown, the present invention includes: a frame 1, a fixed platform 2, a moving platform 3, an electric spindle 4, a first branch 21, a second branch 22, a third branch 23, a fourth branch 24, a fifth branch 25, and a sixth branch 26. The first ends of the first branches 21, 22, 23, 24, and 25 are evenly distributed along the edge of the fixed platform 2; the second ends of the first branches 21, 22, 23, 24, and 25 are evenly distributed along the edge of the moving platform 3; the first end of the sixth branch 26 is installed at the center of the fixed platform 2; the second end of the sixth branch 26 is installed at the center of the first side of the moving platform 3; the electric spindle 4 is installed at the center of the second side of the moving platform 3; the fixed platform 2 is installed at the first end of the frame 1; and the second end of the frame 1 is placed horizontally on the work platform.

[0033] like Figures 1-3As shown, the first branch 21, the second branch 22, the third branch 23, the fourth branch 24, and the fifth branch 25 have the same structure, each including a prismatic joint 5, a first Hooke joint 7, a ball joint 8, and a servo motor 6. Further, the first Hooke joint 7 includes an outer revolute joint 11 and an inner revolute joint 12. The prismatic joint 5, the first Hooke joint 7, and the ball joint 8 form a UPS series branch and are configured as an active, unconstrained branch. The outer revolute joint 11 of the first Hooke joint 7 is connected to the fixed platform 2, and its axis is flush with the opposite side of the fixed platform 2. The inner revolute joint 12 of the first Hooke joint 7 is connected to the first end of the prismatic joint 5, and its axis is perpendicular to the prismatic joint 5. The second end of the prismatic joint 5 is connected to the ball joint 8, which is also connected to the moving platform 3. The servo motor 6, as part of the prismatic joint 5, drives its movement. The servo motor 6 is mounted on the first end of the prismatic joint.

[0034] like Figure 1 , Figure 2 and Figure 4 As shown, the sixth branch 26 includes a second Hooke hinge 9, a passive telescopic rod 10, and a third Hooke hinge 15. Further, the second Hooke hinge 9 includes a second Hooke hinge outer revolute joint 13 and a second Hooke hinge inner revolute joint 14. The third Hooke hinge 15 includes a third Hooke hinge outer revolute joint 16 and a third Hooke hinge inner revolute joint 17. The second Hooke hinge 9, the passive telescopic rod 10, and the third Hooke hinge 15 form a UPU branch and are configured as a passive constraint branch. The second Hooke hinge outer revolute joint 13 of the second Hooke hinge 9 is installed in the center of the fixed platform 2, and the second Hooke... The axis of the external rotating joint 13 is flush with the edge of the fixed platform 2. The internal rotating joint 14 of the second Hooke hinge 9 is connected to the first end of the passive telescopic rod 10, and the axis of the internal rotating joint 14 of the second Hooke hinge is perpendicular to the axis of the passive telescopic rod 10. The second end of the passive telescopic rod 10 is connected to the internal rotating joint 17 of the third Hooke hinge 15, and the axis of the passive telescopic rod 10 is perpendicular to the axis of the internal rotating joint 17 of the third Hooke hinge. The external rotating joint 13 of the second Hooke hinge 15 is connected to the center position of the moving platform 3.

[0035] The first branch 21, the second branch 22, the third branch 23, the fourth branch 24, and the fifth branch 25, as active unconstrained branches, have six degrees of freedom and do not provide constraints on the moving platform 3. The sixth branch 26, as a passively constrained branch, has five degrees of freedom and provides an independent helical constraint on the moving platform 3. Therefore, five servo motors 6 can be used to drive the active unconstrained branches, and the five prismatic joints 5 in the first branch 21, the second branch 22, the third branch 23, the fourth branch 24, and the fifth branch 25 can move, thereby enabling the electric spindle 4 on the moving platform 3 to complete two translations, two rotations, and one independent helical motion.

[0036] like Figure 5 As shown, the feasibility of the present invention can be demonstrated by the constraint screw of its sixth branch 26. It can be represented as: ; In the formula, α represents the rotation angle of the inner revolute joint 17 of the third Hooke hinge about the outer revolute joint 16 of the third Hooke hinge, β represents the rotation angle of the passive telescopic rod 10 about the inner revolute joint 17 of the third Hooke hinge, λ represents the rotation angle of the passive telescopic rod 10 about the inner revolute joint 14 of the second Hooke hinge, L represents the length of the passive telescopic rod 10, and c α =cos(α), s α =sin(α), c β =cos(β), s β =sin(β), c λ =cos(λ), s λ =sin(λ).

[0037] The pitch of the constraint screw in branch 26 is: ; In the formula, α represents the rotation angle of the inner revolute joint 17 of the third Hooke hinge about the outer revolute joint 16 of the third Hooke hinge, β represents the rotation angle of the passive telescopic rod 10 about the inner revolute joint 17 of the third Hooke hinge, λ represents the rotation angle of the passive telescopic rod 10 about the inner revolute joint 14 of the second Hooke hinge, L represents the length of the passive telescopic rod 10, h represents the pitch of the constraint screw of the sixth branch 26, and c α =cos(α), s α =sin(α), c β =cos(β), s β =sin(β), c λ =cos(λ), s λ =sin(λ).

[0038] By analyzing that the pitch of the constraint spiral of the sixth branch 26 under different postures is neither zero nor infinite, it is proved that the passive constraint branch, namely the sixth branch 26, can provide an independent spiral state constraint for parallel machine tools.

[0039] The motion screw at the end of the parallel machine tool is obtained by constraining the screw and then reversing the screw, as follows: ; Where $1 and $2 represent rotational motion, $4 and $5 represent translational motion, and $3 represents independent helical motion. That is, the end-effector motion of this invention consists of two rotations, two translations, and one independent helical motion. α =cos(α), s α =sin(α), c β =cos(β), sβ =sin(β), c λ =cos(λ), s λ =sin(λ), t α =tan(α).

[0040] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A five-degree-of-freedom parallel machine tool with helical-state constrained passive branches, characterized in that: It includes: Frame, fixed platform, moving platform, electric spindle, first branch, second branch, third branch, fourth branch, fifth branch and sixth branch; The first, second, third, fourth, and fifth branches have their first ends evenly distributed on the fixed platform and their second ends evenly distributed on the moving platform. The first end of the sixth branch is installed in the center of the fixed platform, and its second end is installed in the center of the first side of the moving platform. An electric spindle is installed in the center of the second side of the moving platform. The fixed platform is installed at the first end of the frame. The first branch, second branch, third branch, fourth branch, and fifth branch, as active unconstrained branches, each include a prismatic joint, a first Hooke's joint, and a ball joint. The first Hooke's joint connects both the fixed platform and the first end of the prismatic joint. The second end of the prismatic joint connects to the ball joint, which in turn connects to the moving platform. The first Hooke's joint includes an outer revolute joint and an inner revolute joint. The outer revolute joint connects to the fixed platform, the inner revolute joint connects to the first end of the prismatic joint, and the second end of the prismatic joint connects to the ball joint, which in turn connects to the moving platform. The sixth branch, as a passive constraint branch, includes a second Hooke's hinge, a passive telescopic rod, and a third Hooke's hinge. The second Hooke's hinge connects both the moving platform and the first end of the passive telescopic rod, while the third Hooke's hinge connects both the second end of the passive telescopic rod and the fixed platform. The second Hooke's hinge includes an outer revolute joint and an inner revolute joint. The outer revolute joint is installed at the center of the moving platform, and the inner revolute joint is connected to the first end of the passive telescopic rod, with its axis perpendicular to the axis of the passive telescopic rod. The third Hooke's hinge includes an outer revolute joint and an inner revolute joint. The second end of the passive telescopic rod is connected to the inner revolute joint, and the outer revolute joint is connected to the center of the fixed platform. Constraint Screw of the Sixth Branch Its pitch h6 expression is: ； ； In the formula, α represents the rotation angle of the inner revolute joint of the third Hooke's hinge about the outer revolute joint of the third Hooke's hinge, β represents the rotation angle of the passive telescopic rod about the inner revolute joint of the third Hooke's hinge, λ represents the rotation angle of the passive telescopic rod about the inner revolute joint of the second Hooke's hinge, L represents the length of the passive telescopic rod, and c α =cos(α), s α =sin(α), c β =cos(β), s β =sin(β), c λ =cos(λ), s λ =sin(λ); By vertically positioning the second and third Hooke hinge revolute joints of the sixth branch, the constraint screw of the passive constraint branch is made more flexible. The electric spindle has a finite and non-zero pitch within its workspace, forming an independent helical constraint. Based on the independent helical constraint provided by the passive constraint branch, the electric spindle has five degrees of freedom of motion, including two rotations, two translations, and one independent helical motion.

2. The five-degree-of-freedom parallel machine tool with helical-state constrained passive branches according to claim 1, characterized in that: The motion screw of the moving platform of a parallel machine tool satisfies: ； Where $1 and $2 represent rotational motion, $4 and $5 represent translational motion, $3 represents independent helical motion, and c α =cos(α), s α =sin(α), c β =cos(β), s β =sin(β), c λ =cos(λ), s λ =sin(λ), t α =tan(α).

3. The five-degree-of-freedom parallel machine tool with helical-state constrained passive branches according to claim 1, characterized in that: The axis of the first Hooke hinge external revolute joint is aligned with the opposite side of the fixed platform.

4. The five-degree-of-freedom parallel machine tool with helical-state constrained passive branches according to claim 1, characterized in that: The axis of the revolute joint within the first Hooke's hinge is perpendicular to the axis of the prismatic joint.

5. The five-degree-of-freedom parallel machine tool with helical-state constrained passive branches according to claim 1, characterized in that: The axis of the second Hooke hinge external rotary joint is flush with the edge of the moving platform.

6. The five-degree-of-freedom parallel machine tool with helical-state constrained passive branches according to claim 1, characterized in that: The axis of the passive telescopic rod is perpendicular to the axis of the inner rotating joint of the third Hooke's hinge.

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