Foldable seven-degree-of-freedom hybrid robot

Abstract

The application discloses a foldable seven-degree-of-freedom hybrid robot, and belongs to the technical field of multi-degree-of-freedom hybrid robots. The robot comprises a base, a parallel part and a four-degree-of-freedom serial mechanical arm. The parallel part comprises one UP branch chain as a main support and two UCU branch chains as auxiliary supports, one end of the three is fixed on the base, and the other end is fixedly connected with the serial mechanical arm. The UP branch chain and the two UCU branch chains each comprise one drive, so that the parallel part has three degrees of freedom. The serial mechanical arm provides four degrees of freedom, and together with the parallel part, forms a seven-degree-of-freedom system, so that the end effector has full-dimensional motion capability, and contains one redundant degree of freedom to perform dexterous operation. The application adopts a serial-parallel hybrid configuration, has large working space of the serial mechanism and high rigidity and high precision of the parallel mechanism, and the overall structure is foldable, so that the space utilization rate in a non-working state is greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of multi-degree-of-freedom hybrid robot technology, specifically relating to a foldable seven-degree-of-freedom hybrid robot. Background Technology

[0002] When performing complex tasks such as space station construction and assembly, non-cooperative target acquisition, planetary surface exploration, and equipment maintenance and repair, dangerous or highly challenging operating environments are often encountered, making direct human operation extremely difficult. Robotics technology, due to its high precision, versatility, and efficiency, demonstrates enormous application potential in these fields.

[0003] Currently, most robots widely used in the industrial field are serial robotic arms, typically possessing 6 or 7 degrees of freedom. While serial robotic arms offer advantages such as a large workspace and flexible movement, their stiffness is usually low, leading to significant vibrations in the end effector when it moves away from the base, affecting system stability. Furthermore, due to the cumulative effect of joint errors, the end-effector positioning accuracy of serial robotic arms is relatively limited, and their performance degrades significantly under heavy loads. Parallel robots, on the other hand, offer advantages such as high stiffness, high precision, and strong load-bearing capacity, but their workspace is typically smaller, their movement flexibility is insufficient, and they struggle to adapt to complex and ever-changing task requirements.

[0004] In the existing technology, some studies have disclosed a robotic arm with a lockable telescopic arm. Although the extension and retraction of the arm improves flexibility, the problem of end-effector accuracy has not been fundamentally solved. Moreover, its eight-degree-of-freedom redundant system leads to complex inverse kinematics and difficult control. Other foldable or telescopic robotic arm designs also focus on space storage. While improving rigidity and accuracy, they often sacrifice workspace or movement flexibility.

[0005] In summary, existing robotic technologies suffer from the following shortcomings: it is difficult to balance end-effector accuracy and system rigidity; load-bearing capacity is limited; robots with too many degrees of freedom present challenges in kinematics solutions and control; and robotic arms are bulky, occupying significant space when not in use and making storage inconvenient. Therefore, there is an urgent need for a robotic solution that combines high precision, high rigidity, a large workspace, strong load-bearing capacity, and efficient storage. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a foldable seven-DOF hybrid robot that can improve overall stiffness, end effector accuracy, and system stability, enabling it to have a complete analytical correct solution and foldable capability when not in operation.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A foldable seven-DOF hybrid robot includes:

[0009] The base serves as the mounting base for the hybrid robot.

[0010] The parallel section includes one main support chain and two identical secondary support chains. One end of the main support chain and one end of each secondary support chain are fixedly connected to the base via their respective universal joint frames. The other end of the main support chain and the other end of each secondary support chain are fixedly connected to the parallel end of the parallel section. Each of the main support chain and the two secondary support chains includes a driving device, giving the parallel section three degrees of freedom. The universal joint frames corresponding to the main support chain and the two secondary support chains are parallel to each other, giving the parallel section a completely analytical forward kinematic solution.

[0011] A series four-degree-of-freedom robotic arm, wherein the base of the series four-degree-of-freedom robotic arm is fixedly connected to the parallel end of the parallel part; and the axis of the base of the series four-degree-of-freedom robotic arm is parallel to the axis of the universal joint stationary frame of the parallel end.

[0012] The seven-degree-of-freedom robot, resulting from the combined parallel and serial connections, possesses a fully analytical forward kinematic solution, and the entire robot is foldable in its non-working state.

[0013] The beneficial effects of this invention are as follows:

[0014] By creatively adopting a hybrid configuration that combines a 1UP-2UCU parallel mechanism with a four-degree-of-freedom serial mechanism, the robot effectively integrates the dual advantages of the serial mechanism (large workspace and flexible movement) and the parallel mechanism (high stiffness, high precision, and strong load-bearing capacity), significantly improving the robot's overall performance and adaptability in complex tasks.

[0015] By optimizing the layout of the parallel section, the UP main support chain is designed to be thicker than the UCU secondary support chain, enabling it to bear the main load, thereby significantly improving the robot's overall load-bearing capacity and structural stability.

[0016] By setting the universal joint static frame axis of the UP branch to be parallel to the base universal joint static frame axis of the two UCU branches, the parallel part and even the entire robot system have a fully analytical kinematic forward solution, which greatly simplifies the complexity of kinematic calculation and control algorithm.

[0017] The overall structural design features a foldable function, allowing the robot to be retracted and stored when not in use, significantly reducing the space it occupies and greatly improving space utilization during storage and transportation, thus optimizing the spatial configuration of the work area. Attached Figure Description

[0018] Figure 1This is a schematic diagram of the fully unfolded three-dimensional structure of a foldable seven-degree-of-freedom hybrid robot according to the present invention.

[0019] Figure 2 This is a schematic diagram of the retracted three-dimensional structure and coordinate system of a foldable seven-degree-of-freedom hybrid robot according to the present invention.

[0020] Figure 3 This is a schematic diagram of the retracted lower plane of a foldable seven-DOF hybrid robot according to the present invention.

[0021] Figure 4 This is a schematic diagram of the axis of the base stationary frame;

[0022] Figure 5 Sectional views of the UP branch and the integrated joint;

[0023] Figure 6 The images show cross-sectional views of the UCU branches and the integrated joint.

[0024] Figure label:

[0025] 1. Base; 2. First universal joint stationary frame; 3. First universal joint fixed shaft rotating component; 4. First universal joint moving shaft rotating component; 5. Housing of the first reversible planetary roller screw; 6. First screw; 7. Second base universal joint stationary frame; 8. Second base universal joint fixed shaft rotating component; 9. Second base universal joint moving shaft rotating component; 10. Housing of the second reversible planetary roller screw; 11. Second free-moving rotating shaft; 12. Parallel end; 13. Series base and series first drive; 14. Series first connecting rod and series second drive; 15. Series second connecting rod 16. Series third drive; 17. Series third link and series fourth drive; 18. Series fourth link; 19. Second end universal joint fixed shaft rotating component; 20. Second end universal joint moving shaft rotating component; 21. Double-layer ultra-thin motor drive board; 22. Precision magnetic ring; 23. Frameless motor housing; 24. Frameless motor rotor; 25. First nut housing; 26. First roller cage; 27. First roller; 28. Second nut housing; 29. ​​Second roller cage; 30. Second lead screw; 31. Second free-rotating bearing. Detailed Implementation

[0026] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0027] Reference Figure 1 , Figure 3 As shown, this invention provides a foldable seven-DOF hybrid robot, wherein... Figure 1 The image shown is a 3D view. Figure 3 The diagram shown is of the robot in its folded state; the robot includes:

[0028] Base 1, which is the mounting base of the robot and can be fixed to the facility where the robot needs to be used;

[0029] The parallel part of the UP branch (main support branch, including a drive) has one end of the UP branch, the first universal joint frame 2, fixed on the base 1, and the other end of the UP branch, the parallel end 12, fixedly connected to the series base and the series first drive 13 of the series part.

[0030] The parallel UCU branch (secondary support branch, a total of two branches with identical structures, each containing a drive) has one end of the UCU branch fixed to the base 1 by the second base universal joint frame 7, and the other end of the UCU branch is fixed to the series base and series first drive 13 of the series part. The two UCU branches and the UP branch include a total of three drives, so that the parallel part has three degrees of freedom.

[0031] A serial four-degree-of-freedom robotic arm is provided, wherein the serial base and the serial first drive 13 of the serial four-degree-of-freedom robotic arm are fixedly connected to the parallel end 12 of the parallel part. The serial four-degree-of-freedom robotic arm and the parallel part together have a total of seven degrees of freedom, which enables the robot to have all-dimensional degrees of freedom and has a redundant degree of freedom for dexterous operation.

[0032] In the parallel section, such as Figures 5-6 As shown, the UP branch, as the main support chain, has a total of 3 degrees of freedom. While the UCU secondary support chain possesses all 6 degrees of freedom, its number is limited by the UP branch, resulting in a total of 3 degrees of freedom for the parallel section. When the first lead screw 6 of the UP branch translates, it drives the second lead screws 30 of the two UCU branches to translate, thus enabling the parallel end 12 to achieve the following: Figure 2 The x0 direction of motion is shown; when the first universal joint fixed axis rotating component 3 and the first universal joint moving axis rotating component 4 of the UP branch rotate, they will simultaneously drive the second base universal joint fixed axis rotating component 8 and the second base universal joint moving axis rotating component 9 of the UCU branch to rotate, thereby enabling the parallel end to rotate around... Figure 2 The robot exhibits rotational capabilities around the z0 and y0 axes. The series section contains four drive motors, thus providing four degrees of freedom. Because the rotational axes of the first and second series drives 14 in the series section are linearly independent of those in the parallel section, the entire robot end effector possesses all three spatial rotational capabilities. Furthermore, the axes of the first and second series drives 14 and the third and fourth series drives 16 can remain parallel within permissible limits, thereby deriving capabilities such as… Figure 2 The translational degree of freedom in the y0 direction is shown. When the axes of the first connecting rod and the second drive 14 are parallel to the rotating component 4 of the first universal joint shaft, the following further translational degrees of freedom are derived: Figure 2The figure shows the translational degree of freedom in the x0 direction. Therefore, the entire robot possesses full spatial motion capabilities and has a redundant degree of freedom for performing complex operations.

[0033] Specifically, the UP branch of the parallel section includes a first base universal joint (U pair) and a first reverse planetary roller screw (P pair, driven by a motor). The first universal joint stationary frame 2 is fixed on the base 1. The second base universal joint rotating shaft 9 is fixedly connected to the housing 10 of the second reverse planetary roller screw. The first screw 6 at the output end of the first reverse planetary roller screw is fixedly connected to the parallel end 12 of the parallel section.

[0034] The first universal joint includes a first universal joint stationary frame 2, a first universal joint fixed axis rotating component 3, and a first universal joint moving axis rotating component 4. The first universal joint stationary frame 2 is fixed on the base 1. The first universal joint fixed axis rotating component 3 can rotate around the first universal joint stationary frame 2. The first universal joint moving axis rotating component 4 can rotate around the first universal joint fixed axis rotating component 3. The first universal joint moving axis rotating component 4 is fixedly connected to the housing 5 of the first reversible planetary roller screw. The first universal joint fixed axis rotating component 3 and the first universal joint moving axis rotating component 4 are perpendicularly distributed, and the two together with the first universal joint stationary frame 2 form a universal joint (U-pair).

[0035] The first reversible planetary roller screw includes a housing 5, a first nut housing 24, a first roller cage 25, a plurality of first rollers 26, and a first screw 6. The housing 5 of the first reversible planetary roller screw is fixedly connected to the housing 22 (i.e., the stator of the motor) of the frameless motor. The first nut housing 24 is fixedly connected to the rotor 23 of the frameless motor. The first roller cage 25 is fixedly connected to the first screw 6. The first nut housing 24 is threadedly engaged with the plurality of first rollers 26. The first rollers 26 are mounted on the first roller cage 25 as shown. The plurality of first rollers 26 are arranged in a planetary pattern. The gears of the first rollers 26 are threadedly engaged with the first screw 6. Finally, the first nut housing 24 is driven to rotate by the motor. The first rollers 26 on the first roller cage 25 are driven by the first nut housing 24 to start planetary motion, and then the first rollers 26 drive the first screw 6 to perform linear motion.

[0036] Each of the two UCU branches in the parallel section includes a second base universal joint (U-pair), a second reverse planetary roller screw (including a drive), a second free-rotating bearing 31, a second free-moving rotating shaft 11, and a second end universal joint (U-pair). The second reverse planetary roller screw, the second free-rotating bearing 31, and the second free-moving rotating shaft 11 together form a C-pair. The base frame of the second base universal joint is fixed to the base. The output of the second base universal joint is fixedly connected to the housing of the second reverse planetary roller screw. The output end of the second reverse planetary roller screw is fixedly connected to the input of the second free-rotating bearing. The output of the second free-rotating bearing 31 is fixedly connected to the second free-moving rotating shaft 11. The second free-moving rotating shaft 11 is connected to the base of the second end universal joint. The output of the second end universal joint is connected to the end of the parallel section. Wherein:

[0037] The second base universal joint includes a second base universal joint stationary frame 7, a second base universal joint fixed axis rotating component 8, and a second base universal joint moving axis rotating component 9. The second base universal joint stationary frame 7 is fixed on the base 1. The second base universal joint fixed axis rotating component 8 can rotate around the second base universal joint stationary frame 7. The second base universal joint moving axis rotating component 9 can rotate around the second base universal joint fixed axis rotating component 8. The second base universal joint moving axis rotating component 9 is fixedly connected to the housing 10 of the second reverse planetary roller screw. The second base universal joint fixed axis rotating component 8 and the second base universal joint moving axis rotating component 9 are perpendicularly distributed, and the two together with the second base universal joint stationary frame 7 form a universal joint (U-pair).

[0038] The second reversible planetary roller screw includes a housing 10, a second nut housing 27, a second roller cage 28, multiple second rollers 29, and a second screw 30. The housing 10 of the second reversible planetary roller screw is fixedly connected to the housing 22 (i.e., the stator of the motor) of the frameless motor. The second nut housing 27 is fixedly connected to the rotor 23 of the frameless motor. The second roller cage 28 is fixedly connected to the second screw 30. The second nut housing 27 is threadedly engaged with the multiple second rollers 29. The second rollers 29 are mounted on the second roller cage 28. The multiple second rollers 29 are arranged in a planetary pattern. The gears of the second rollers 29 are threadedly engaged with the second screw 30. Finally, the second nut housing 27 is driven to rotate by the motor. The second rollers 29 on the second roller cage 28 are driven by the second nut housing 27 to start planetary motion, and then the second rollers 29 drive the second screw 30 to perform linear motion.

[0039] The second end universal joint includes a second end universal joint stationary frame, a second end universal joint fixed axis rotating component 18, and a second end universal joint moving axis rotating component 19. The second end universal joint stationary frame is part of the parallel end 12 (not shown in the figure). The second end universal joint fixed axis rotating component 18 can rotate around the second end universal joint stationary frame, and the second end universal joint moving axis rotating component 19 can rotate around the second end universal joint fixed axis rotating component 18. The second end universal joint moving axis rotating component 19 is fixedly connected to the second lead screw 30. The second end universal joint fixed axis rotating component 18 and the second end universal joint moving axis rotating component 19 are perpendicularly distributed, and the two together with the second end universal joint stationary frame form a universal joint (U-pair).

[0040] like Figures 5-6 As shown, the UP branch in the parallel section is designed to be thicker than the UCU branch in the parallel section, and the UP branch needs to have a greater load-bearing capacity than the UCU branch.

[0041] like Figure 4 As shown, the axis of the first universal joint stationary frame 2 in the UP branch and the axis of the second base universal joint stationary frame 7 in the UCU branch need to be completely parallel. The parallel part has a completely analytical correct solution. The analytical correct solution analysis of the parallel part is as follows:

[0042] For the UP-2UCU parallel section of the entire robotic arm, the UP branch is established as follows: Figure 2 The coordinate system shown. Parameter a in the DH method. i This refers to the length of the common perpendicular between the axes of the kinematic joints at both ends of link i; the torsion angle α of link i. i Defined as the joint axis at both ends of link i within the length a of link i. i The angle between the projections of the rod onto the normal plane; rod length a i-1 With a i The two line segments intersect the axis of joint i at two points, and the distance between these points is denoted by d. i This is represented as the distance between adjacent links i-1 and i; in the plane perpendicular to the axis of joint i, line segment a... i-1 and a i The included angle θ i This is called the angle between adjacent links i-1 and i. The DH matrix for this UP branch is shown in Table 1.

[0043] Table 1

[0044]

[0045] Where s is the distance between point O and point D in the UP branch, g is the projection distance from point E to the origin of coordinate system O3X3Y3Z3 on the z4 axis, and θ1 and θ2 are the two rotation angles of the parallel main branch U relative to the initial pose.

[0046] In the base coordinate system, the coordinates of points O, B, and C can be represented as: O(0, 0, 0), B(h, 0, -b), C(h, 0,b).

[0047] In the coordinate system O3X3Y3Z3, the coordinates of points D, E, and F can be represented as: D(-e, g, 0), E(-e, g, -r), F(-e, g, r). Where h is the projection distance from point B or C to the origin O of the base coordinate system on the x0 axis, b is the distance from point B or C to the x0 axis, e is the projection distance from point D to the origin of the coordinate system O3X3Y3Z3 on the x3 axis, and r is the distance from point E or F to point D.

[0048] Assuming the rotation angles of the main UP branch around z0 and z1 are θ1 and θ2, the lengths of the three branches need to be calculated first based on the parallel structure. That is, the inverse solutions s and S of the parallel part need to be obtained based on the position of point D. b S c Among them, S b Let S be the distance between points B and E in a UCU branch. c Let C be the distance between point C and point F in another UCU branch.

[0049] Based on Table 1, the coordinate transformation matrices between the three adjacent coordinate systems can be obtained using the DH method as follows:

[0050] ,

[0051] Based on the coordinates of points E and F in the base coordinate system, it can be expressed as:

[0052] ,

[0053] Where sθ represents sinθ and cθ represents cosθ.

[0054] Furthermore, the lengths of BE and CF in the two UCU branches can be calculated using the two-point distance formula, i.e.:

[0055] ,

[0056] Observe S b and S c The expression can be analyzed to obtain:

[0057] ,

[0058] make ,set up Therefore, we can rearrange the above two equations into a quartic equation in x as shown below:

[0059]

[0060] The expressions for each coefficient are as follows:

[0061] ,

[0062] By applying the quadratic formula for a quartic equation and combining it with the current configuration of the parallel section, the four roots of x can be calculated. The most suitable value is then selected to determine θ1, followed by θ2. Finally, using the forward calculus formula for the serial manipulator, the pose of the UP branch end is calculated, thus obtaining the pose of the parallel end. .

[0063] The serial four-degree-of-freedom robotic arm includes a serial base and serial first drive 13, serial first link and serial second drive 14, serial second link and serial third drive 15, serial third link and serial fourth drive 16, and serial fourth link (the end of the entire system) 17. The serial base and serial first drive 13 are fixedly connected to the parallel end 12. The rotor of the serial base and serial first drive 13 is fixedly connected to the stator of the serial first link and serial second drive 14. The rotor of the serial first link and serial second drive 14 is fixedly connected to the stator of the serial second link and serial third drive 15. The rotor of the serial second link and serial third drive 15 is fixedly connected to the stator of the serial third link and serial fourth drive 16. The rotor of the serial third link and serial fourth drive 16 is fixedly connected to the serial fourth link 17.

[0064] The axes of the series base and the series first drive 13 are parallel to the axis of the universal joint stationary frame at the second end of the parallel part. The axes of the series first link and the series second drive 14 are perpendicular to the axes of the series base and the series first drive 13. The axes of the series second link and the series third drive 15 are perpendicular to the axes of the series first link and the series second drive 14. The axes of the series third link and the fourth drive 16 are perpendicular to the axes of the series second link and the third drive 15. The axes of the series first link and the second drive 14, the series second link and the third drive 15, and the series third link and the fourth drive 16 will intersect at a point in any posture of the series part.

[0065] The drive motor of the parallel section is an integrated motor, including: a frameless motor housing (stator) 22, a frameless motor rotor 23, a double-layer ultra-thin motor drive plate 20, and a precision magnetic ring 21. The components of the integrated motor in the parallel section are arranged coaxially, and the double-layer ultra-thin motor drive plate 20 and the precision magnetic ring 21 are fixedly connected to the frameless motor housing 22.

[0066] The entire end effector of the robot possesses a completely analytical positive solution. The specific analysis is as follows:

[0067] For the serial part of the robotic arm, establish as follows Figure 2 The coordinate system is shown. Based on the structure of this four-degree-of-freedom serial robotic arm, its DH parameters can be obtained as shown in Table 2.

[0068] Table 2

[0069]

[0070] Where t represents the distance between the two parallel lines of z3 axis and z5 axis, m represents the distance between the skew lines of z5 axis and x7 axis, and θ4-θ7 are the rotation angles of each link in the series connection relative to the initial pose.

[0071] Therefore, the transformation matrix of adjacent coordinate systems can be constructed according to the DH method as follows:

[0072] ,

[0073] Therefore, the correct solution for the series connection can be expressed as:

[0074] ,

[0075] Since the end-effector coordinate system of the parallel section coincides with O3X3Y3Z3, the forward solution of the entire seven-DOF hybrid robot can be obtained first from the end-effector pose obtained from the parallel section. and the pose transformation matrix of the concatenated part get:

[0076] ,

[0077] The parallel section and the series four-degree-of-freedom robotic arm are foldable in the non-working state, such as... Figure 2 , Figure 3 As shown, the space occupied at this point almost entirely includes the volume of the device itself. However, typical parallel or hybrid robots cannot be folded, so the space occupied in their non-working and working states is similar. The parallel components, due to workspace limitations, often have to be kept in a similar position. Figure 1 The parallel configuration in the previous invention greatly increases the space occupied and results in low space utilization. As mentioned above, the design of this invention saves storage space.

[0078] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A foldable seven-DOF hybrid robot, characterized in that, include: The base serves as the mounting base for the hybrid robot. The parallel section includes one main support chain and two identical secondary support chains. One end of the main support chain and one end of each secondary support chain are fixedly connected to the base via their respective universal joint frames. The other end of the main support chain and the other end of each secondary support chain are fixedly connected to the parallel end of the parallel section. Each of the main support chain and the two secondary support chains includes a driving device, giving the parallel section three degrees of freedom. The universal joint frames corresponding to the main support chain and the two secondary support chains are parallel to each other, giving the parallel section a completely analytical forward kinematic solution. A series four-degree-of-freedom robotic arm, wherein the base of the series four-degree-of-freedom robotic arm is fixedly connected to the parallel end of the parallel part; and the axis of the base of the series four-degree-of-freedom robotic arm is parallel to the axis of the universal joint stationary frame of the parallel end. The seven-degree-of-freedom robot, which is achieved by the parallel and serial components, has a fully analytical forward kinematic solution, and the entire robot is foldable in the non-working state. The main support chain is a UP kinematic chain, including a first universal joint and a first reverse planetary roller screw; the base of the first universal joint is fixed on the base, the output of the first universal joint is fixedly connected to the housing of the first reverse planetary roller screw, and the output end of the first reverse planetary roller screw is fixedly connected to the parallel end. The two secondary support chains of the parallel section are UCU chains, each including a second base universal joint as a U-type pair, a second reverse planetary roller screw, a second free-rotating bearing, a second free-moving rotating shaft, and a second end universal joint as another U-type pair. The second reverse planetary roller screw, the second free-rotating bearing, and the second free-moving rotating shaft together form a C-type pair. The base frame of the second base universal joint is fixed on the base. The output of the second base universal joint is fixedly connected to the housing of the second reverse planetary roller screw. The output end of the second reverse planetary roller screw is fixedly connected to the input of the second free-rotating bearing. The output of the second free-rotating bearing is fixedly connected to the second free-moving rotating shaft. The second free-moving rotating shaft is connected to the base of the second end universal joint. The output of the second end universal joint is connected to the end of the parallel section. The second end universal joint includes a second end universal joint stationary frame, a second end universal joint fixed-axis rotating component, and a second end universal joint movable-axis rotating component. The second end universal joint stationary frame is part of the parallel end. The second end universal joint fixed-axis rotating component can rotate around the second end universal joint stationary frame. The second end universal joint movable-axis rotating component can rotate around the second end universal joint fixed-axis rotating component. The second end universal joint movable-axis rotating component is fixedly connected to the second lead screw. The second end universal joint fixed-axis rotating component and the second end universal joint movable-axis rotating component are perpendicularly distributed.

2. The foldable seven-DOF hybrid robot according to claim 1, characterized in that, The first universal joint includes a first universal joint stationary frame, a first universal joint fixed axis rotating component, and a first universal joint moving axis rotating component. The first universal joint stationary frame is fixed on the base. The first universal joint fixed axis rotating component can rotate around the first universal joint stationary frame. The first universal joint moving axis rotating component can rotate around the first universal joint fixed axis rotating component. The first universal joint moving axis rotating component is fixedly connected to the housing of the first reversible planetary roller screw. The first universal joint fixed axis rotating component and the first universal joint moving axis rotating component are perpendicularly distributed.

3. The foldable seven-DOF hybrid robot according to claim 2, characterized in that, The first reversible planetary roller screw includes a housing, a first nut housing, a first roller cage, a plurality of first rollers, and a first screw. The housing of the first reversible planetary roller screw is fixedly connected to the housing of a frameless motor. The first nut housing is fixedly connected to the rotor of the frameless motor. The first roller cage is fixedly connected to the first screw. The first nut housing is threadedly engaged with the plurality of first rollers. The first rollers are mounted on the first roller cage. The plurality of first rollers are arranged in a planetary pattern. The gears of the first rollers are threadedly engaged with the first screw. The first nut housing is driven to rotate by the motor. The first rollers on the first roller cage are driven by the first nut housing to begin planetary motion, and then the first rollers drive the first screw to perform linear motion.

4. The foldable seven-DOF hybrid robot according to claim 1, characterized in that, The second base universal joint includes a second base universal joint stationary frame, a second base universal joint fixed-axis rotating component, and a second base universal joint moving-axis rotating component. The second base universal joint stationary frame is fixed on the base. The second base universal joint fixed-axis rotating component can rotate around the second base universal joint stationary frame. The second base universal joint moving-axis rotating component can rotate around the second base universal joint fixed-axis rotating component. The second base universal joint moving-axis rotating component is fixedly connected to the housing of the second reverse planetary roller screw. The second base universal joint fixed-axis rotating component and the second base universal joint moving-axis rotating component are perpendicularly distributed.

5. A foldable seven-DOF hybrid robot according to claim 1, characterized in that, The second reversible planetary roller screw includes a housing, a second nut housing, a second roller cage, multiple second rollers, and a second screw. The housing of the second reversible planetary roller screw is fixedly connected to the housing of a frameless motor. The second nut housing is fixedly connected to the rotor of the frameless motor. The second roller cage is fixedly connected to the second screw. The second nut housing is threadedly engaged with the multiple second rollers. The second rollers are mounted on the second roller cage. The multiple second rollers are arranged in a planetary pattern. The gears of the second rollers are threadedly engaged with the second screw. The second nut housing is driven to rotate by the motor. The second rollers on the second roller cage are driven by the second nut housing to begin planetary motion, and then the second rollers drive the second screw to perform linear motion.

6. A foldable seven-DOF hybrid robot according to claim 1, characterized in that, The serial four-degree-of-freedom robotic arm includes a serial base and serial first drive, serial first link and serial second drive, serial second link and serial third drive, serial third link and serial fourth drive, and serial fourth link. The serial base and serial first drive are fixedly connected to the parallel end. The rotor of the serial base and serial first drive is fixedly connected to the stator of the serial first link and serial second drive. The rotor of the serial first link and serial second drive is fixedly connected to the stator of the serial second link and serial third drive. The rotor of the serial second link and serial third drive is fixedly connected to the stator of the serial third link and serial fourth drive. The rotor of the serial third link and serial fourth drive is fixedly connected to the serial fourth link.

7. A foldable seven-DOF hybrid robot according to claim 6, characterized in that, The axes of the series base and the series first drive are parallel to the axis of the universal joint stationary frame at the second end of the parallel part. The axes of the series first link and the series second drive are perpendicular to the axes of the series base and the series first drive. The axes of the series second link and the series third drive are perpendicular to the axes of the series first link and the series second drive. The axes of the series third link and the fourth drive are perpendicular to the axes of the series second link and the third drive. The axes of the series first link and the second drive, the series second link and the third drive, and the series third link and the fourth drive will intersect at a point in any posture of the series part.

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