Four-module eight-connecting-rod redundant drive novel six-degree-of-freedom parallel mechanism

Abstract

The invention provides a four-module eight-connecting-rod redundant drive novel six-degree-of-freedom parallel mechanism. The mechanism comprises eight actuating rod assemblies A, eight sliding plate assemblies B and four module assemblies C which are arranged between a movable platform D and a static platform F, according to the mechanism, a redundant drive mode is adopted, dynamics optimization of the four-module eight-connecting-rod redundant drive novel six-degree-of-freedom parallel mechanism is achieved, the purposes of reducing the peak-to-valley ratio, the maximum drive force and the motor power are achieved, and the life safety of laboratory personnel is guaranteed to a certain degree.

Description

Technical Field

[0001] The present invention relates to the technical field of dynamics optimization, and particularly relates to a novel six-degree-of-freedom parallel mechanism with four-module eight-link redundant drive. Background Art

[0002] The Stewart platform was proposed by the American scholar Stewart in 1965. See Figure 1 , the Stewart platform consists of an upper platform, a lower platform and six actuating rods. By controlling the six actuating rods, the six-degree-of-freedom movement of the upper platform in space can be realized. It has the advantages of stable structure, high precision, good rigidity, etc. It is widely used in industrial robots, flight simulators, medical rehabilitation, CNC machine tools, radio telescopes and other fields.

[0003] However, the working space of the Stewart platform is limited, and when using a hydraulic cylinder, the quality of the hydraulic oil will change. For the Stewart platform driven by an electric cylinder or a hydraulic cylinder, its driving components include a lead screw, a lead screw nut, a motor, a speed reducer, and a cylinder block, a piston, a piston rod, etc. These driving components participate in the movement, resulting in a large moving mass; at the same time, power cables, signal cables, sensors or high-pressure oil pipes, etc. are installed on these moving components, reducing the reliability of the mechanism. The Stewart platform has no mechanism redundancy and drive redundancy. When a failure such as a broken rod, power failure, abnormal braking, loss of enable, or oil pipe rupture occurs in one actuating rod, it will cause the actuating rod to fail to work properly or completely lose its supporting function, resulting in the collapse or uncontrollable dangerous movement of the upper platform, and it is extremely easy to cause accidents such as equipment damage and personal injury.

[0004] Therefore, it is of great significance to develop a novel six-degree-of-freedom parallel mechanism with four-module eight-link redundant drive. Summary of the Invention

[0005] The purpose of the present invention is to provide a novel six-degree-of-freedom parallel mechanism with four-module eight-link redundant drive to solve the problems existing in the prior art.

[0006] The technical solution adopted to achieve the purpose of the present invention is as follows: a novel six-degree-of-freedom parallel mechanism with four-module eight-link redundant drive includes 8 actuating rod assemblies A, 8 slide plate assemblies B, and 4 module assemblies C arranged between a moving platform D and a static platform F.

[0007] The 4 module assemblies C are arranged on the static platform F. The connecting lines of the midpoint projection points of the 4 module assemblies C form a rectangle. Each module assembly C is provided with a connecting groove. Two slide plate assemblies B are movably arranged in each connecting groove. The slide plate assembly B has a slide plate ball hinge mounting seat.

[0008] On one side plate surface of the moving platform D facing the static platform F, there are 4 groups of moving platform ball hinge seats evenly distributed along the circumferential direction. Each group of moving platform ball hinge seats includes two moving platform ball hinge seats E.

[0009] Both ends of the actuating rod assembly A have ball hinges. One end of each actuating rod assembly A is hinged on the corresponding moving platform ball hinge seat E, and the other end is hinged on the corresponding slide plate ball hinge mounting seat.

[0010] During operation, the drive slides the slide plate assembly B, the synchronous belt drives the actuating rod assembly A to move, and then drives the moving platform D to perform six-degree-of-freedom motion. The redundant drive method is adopted to achieve dynamic optimization. Six slide plate assemblies B are selected as non-redundant drives and the position drive mode is adopted. Two slide plate assemblies B are selected as redundant drives and the torque drive mode is adopted.

[0011] Furthermore, the 8 actuating rod assemblies A are sequentially marked as A1, A2, A3, A4, A5, A6, A7, and A8 in the counterclockwise direction. A7 and A8 are selected as redundant drive rods. The 4 module assemblies C are sequentially marked as C1, C2, C3, and C4 in the counterclockwise direction. The connection grooves are arranged on the opposite sides of C1 and C4, and on the opposite sides of C2 and C3. The 8 slide plate assemblies B are sequentially marked as B1, B2, B3, B4, B5, B6, B7, and B8. B1 and B2 are slidably arranged in the connection groove of C1, B3 and B4 are slidably arranged in the connection groove of C2, B5 and B6 are slidably arranged in the connection groove of C3, and B7 and B8 are slidably arranged in the connection groove of C4. The 8 moving platform ball hinge seats E are sequentially marked as E1, E2, E3, E4, E5, E6, E7, and E8 in the counterclockwise direction. E1 and E8 form a group, E2 and E3 form a group, E4 and E5 form a group, and E6 and E7 form a group. One end of A1 is hinged on E1, and the other end is hinged on the corresponding slide plate ball hinge mounting seat of B1. One end of A2 is hinged on E2, and the other end is hinged on the corresponding slide plate ball hinge mounting seat of B2. One end of A3 is hinged on E3, and the other end is hinged on the corresponding slide plate ball hinge mounting seat of B3. One end of A4 is hinged on E4, and the other end is hinged on the corresponding slide plate ball hinge mounting seat of B4. One end of A5 is hinged on E5, and the other end is hinged on the corresponding slide plate ball hinge mounting seat of B5. One end of A6 is hinged on E6, and the other end is hinged on the corresponding slide plate ball hinge mounting seat of B6. One end of A7 is hinged on E7, and the other end is hinged on the corresponding slide plate ball hinge mounting seat of B7. One end of A8 is hinged on E8, and the other end is hinged on the corresponding slide plate ball hinge mounting seat of B8.

[0012] Furthermore, B2 is arranged above B1. B3 is arranged above B4. B6 is arranged above B5. B7 is arranged above B7. The slide plate ball hinge mounting seats of the two slide plate assemblies B installed on the same module assembly C of the slide plate assembly Bi are arranged in a staggered manner.

[0013] Further, according to the specified trajectory planning of the moving platform D in the workspace, the kinematics and dynamics of the mechanism are solved to obtain the optimized value of the driving force. The positions of the six non-redundant driving slide plate assemblies B are adjusted through position servo control, and the positions of the two redundant driving slide plate assemblies B are adjusted through force servo control.

[0014] Further, the slide plate assembly B is driven to move by a double-motor and double-screw drive mode.

[0015] The technical effects of the present invention are beyond doubt:

[0016] A. The lower platform of the mechanism occupies a small planar space. The dimensions of the mechanism in the X / Y directions are small.

[0017] B. The module components adopt the concept of space sharing. Two sets of slide plates are installed on the same module to achieve a more compact structural design. The Z-direction stroke is large. By increasing the length of the guide rail, a large Z-direction stroke can be achieved.

[0018] C. By adopting a redundant drive mode, the dynamics of the new six-degree-of-freedom parallel mechanism with four modules and eight-link redundant drive is optimized, achieving the purpose of reducing the peak-to-valley ratio, the maximum driving force, and the motor power, and ensuring the life safety of laboratory personnel to a certain extent. Description of the Drawings

[0019] Figure 1 is a schematic diagram of a Stewart platform;

[0020] Figure 2 is a schematic diagram of a parallel mechanism with eight-link redundant drive;

[0021] Figure 3 is a schematic diagram of the moving platform. Detailed Embodiments

[0022] The present invention will be further described below in conjunction with embodiments, but it should not be understood that the above-mentioned subject matter scope of the present invention is limited to the following embodiments. Without departing from the above-mentioned technical idea of the present invention, various substitutions and changes made according to the common general knowledge and conventional means in the art should be included within the protection scope of the present invention.

[0023] Embodiment 1:

[0024] This embodiment provides a new six-degree-of-freedom parallel mechanism with four modules and eight-link redundant drive, including 8 actuator rod assemblies A, 8 slide plate assemblies B, and 4 module assemblies C arranged between the moving platform D and the static platform F.

[0025] The four module components C are arranged on the static platform F. The connecting lines of the midpoint projection points of the four module components C form a rectangle. Each module component C is provided with a connecting groove. Two sliding plate components B are movably arranged in each connecting groove. The module components adopt the concept of spatial sharing, and two sets of sliding plates are installed on the same module to achieve a more compact structural design. The sliding plate component B is provided with a sliding plate ball hinge mounting seat.

[0026] On one side surface of the moving platform D facing the static platform F, four groups of moving platform ball hinge seats are evenly distributed in the circumferential direction. Each group of moving platform ball hinge seats includes two moving platform ball hinge seats E.

[0027] Both ends of the actuating rod component A have ball hinges. One end of each actuating rod component A is hinged to the corresponding moving platform ball hinge seat E, and the other end is hinged to the corresponding sliding plate ball hinge mounting seat.

[0028] During operation, the sliding plate component B is driven to move, the synchronous belt drives the actuating rod component A to move, and then drives the moving platform D to perform six-degree-of-freedom motion. The redundant drive mode is adopted to realize dynamic optimization. Six sliding plate components B are selected as non-redundant drives and the position drive mode is adopted. Two sliding plate components B are selected as redundant drives and the torque drive mode is adopted.

[0029] Embodiment 2:

[0030] The main content of this embodiment is the same as that of Embodiment 1. Among them, referring to Figure 2 and Figure 3 , the eight actuating rod components A are sequentially marked as A1, A2, A3, A4, A5, A6, A7, and A8 in the counterclockwise direction. A7 and A8 are selected as redundant drive rods. Refer to Figure 2, 2a and 2b respectively represent different views. O-xyz is the absolute coordinate system, and O1-x1y1z1 is the moving coordinate system. In this embodiment, the z-axis can be arranged at any angle. The 4 module components C are sequentially marked as C1, C2, C3, and C4 in the counterclockwise direction. The connecting grooves are arranged on the opposite sides of C1 and C4, and on the opposite sides of C2 and C3. The 8 slide plate components B are sequentially marked as B1, B2, B3, B4, B5, B6, B7, and B8. B1 and B2 are slidably arranged in the connecting groove of C1, B3 and B4 are slidably arranged in the connecting groove of C2, B5 and B6 are slidably arranged in the connecting groove of C3, and B7 and B8 are slidably arranged in the connecting groove of C4. The 8 moving platform ball hinge seats E are sequentially marked as E1, E2, E3, E4, E5, E6, E7, and E8 in the counterclockwise direction. E1 and E8 are a group, E2 and E3 are a group, E4 and E5 are a group, and E6 and E7 are a group. One end of A1 is hinged to E1, and the other end is hinged to the corresponding slide plate ball hinge mounting seat of B1. One end of A2 is hinged to E2, and the other end is hinged to the corresponding slide plate ball hinge mounting seat of B2. One end of A3 is hinged to E3, and the other end is hinged to the corresponding slide plate ball hinge mounting seat of B3. One end of A4 is hinged to E4, and the other end is hinged to the corresponding slide plate ball hinge mounting seat of B4. One end of A5 is hinged to E5, and the other end is hinged to the corresponding slide plate ball hinge mounting seat of B5. One end of A6 is hinged to E6, and the other end is hinged to the corresponding slide plate ball hinge mounting seat of B6. One end of A7 is hinged to E7, and the other end is hinged to the corresponding slide plate ball hinge mounting seat of B7. One end of A8 is hinged to E8, and the other end is hinged to the corresponding slide plate ball hinge mounting seat of B8.

[0031] B2 is arranged above B1. B3 is arranged above B4. B6 is arranged above B5. B7 is arranged above B7. The slide plate ball hinge mounting seats of the two slide plate components B installed on the same module component C are arranged in a staggered manner.

[0032] Embodiment 3:

[0033] The main content of this embodiment is the same as that of Embodiment 1 or 2, wherein the movement of the slide plate component B is driven by a double-motor double-screw drive mode.

[0034] Embodiment 4:

[0035] The main content of this embodiment is the same as that of Embodiment 2. Among them, in this embodiment, according to the specified trajectory planning of the moving platform D in the workspace, the kinematics and dynamics of the mechanism are solved, the optimized value of the driving force is solved, the positions of the six non-redundant driving slide plate assemblies B are adjusted through position servo control, and the positions of the two redundant driving slide plate assemblies B are adjusted through force servo control. The number of drives of the mechanism in this embodiment is greater than the number of degrees of freedom of the mechanism. 1 to 6 are selected as non-redundant drives and the position drive mode is adopted, and 7 to 8 are selected as redundant drives and the torque drive mode is adopted. The control system completes the kinematics and dynamics solutions of the mechanism according to the specified trajectory planning of the moving platform in the workspace, then uses an optimization algorithm to solve the optimized value of the driving force, and finally adjusts the positions of the six driving joints and the driving forces of the two driving joints through the position servo control system and the force servo control system respectively.

Claims

1. A new type of six-degree-of-freedom parallel mechanism with four modules and eight links with redundant drive, characterized by: It includes 8 actuator rod assemblies (A), 8 slide assemblies (B), and 4 module assemblies (C) arranged between a moving platform (D) and a static platform (F); The four module assemblies (C) are arranged on a static platform (F); the midline projection points of the four module assemblies (C) are connected to form a rectangle; each module assembly (C) is provided with a connecting groove; two slide assemblies (B) are movably provided in each connecting groove; the slide assemblies (B) are provided with a slide ball joint mounting seat; Four groups of moving platform ball joints are evenly distributed along the circumference on a side plate surface of the moving platform (D) facing the static platform (F); each group of moving platform ball joints includes two moving platform ball joints (E); Both ends of the actuating rod assembly (A) are provided with ball joints; one end of each actuating rod assembly (A) is hinged to the corresponding moving platform ball joint seat (E), and the other end is hinged to the corresponding skateboard ball joint mounting seat; When working, the driving slide assembly (B) moves, which synchronously drives the moving rod assembly (A) to move, and then drives the moving platform (D) to move with six degrees of freedom; a redundant drive method is used to achieve dynamic optimization; 6 slide assemblies (B) are selected as non-redundant drives, and a position drive mode is adopted; 2 slide assemblies (B) are selected as redundant drives, and a torque drive mode is adopted.

2. According to claim 1, a four-module eight-link redundant drive novel six-degree-of-freedom parallel mechanism is characterized by: The 8 actuator rod assemblies (A) are marked as A1, A2, A3, A4, A5, A6, A7 and A8 in the counterclockwise direction; A7 and A8 are selected as redundant drive rods; the 4 module assemblies (C) are marked as C1, C2, C3 and C4 in the counterclockwise direction; the connecting grooves are arranged on the side opposite to C1 and C4, and on the side opposite to C2 and C3; the 8 sliding plate assemblies (B) are marked as B1, B2, B3, B4, B5, B6, B7 and B8 in sequence; B1 and B2 are slidably arranged in the connecting groove of C1, B3 and B4 are slidably arranged in the connecting groove of C2, B5 and B6 are slidably arranged in the connecting groove of C3, and B7 and B8 are slidably arranged in the connecting groove of C4; the 8 moving platform ball joint seats (E) are marked as E1, E2, E3, E4, E5, E6, E7 and E8 in the counterclockwise direction; E1 A1 is a group with E8, E2 and E3 are a group, E4 and E5 are a group, and E6 and E7 are a group; one end of A1 is hinged on E1, and the other end is hinged on the skateboard ball joint mounting seat corresponding to B1; one end of A2 is hinged on E2, and the other end is hinged on the skateboard ball joint mounting seat corresponding to B2; one end of A3 is hinged on E3, and the other end is hinged on the skateboard ball joint mounting seat corresponding to B3; one end of A4 is hinged on E4, and the other end is hinged on the skateboard ball joint mounting seat corresponding to B4; one end of A5 is hinged on E5, and the other end is hinged on the skateboard ball joint mounting seat corresponding to B5; one end of A6 is hinged on E6, and the other end is hinged on the skateboard ball joint mounting seat corresponding to B6; one end of A7 is hinged on E7, and the other end is hinged on the skateboard ball joint mounting seat corresponding to B7; one end of A8 is hinged on E8, and the other end is hinged on the skateboard ball joint mounting seat corresponding to B8.

3. According to claim 2, a four-module eight-link redundant drive novel six-degree-of-freedom parallel mechanism is characterized by: B2 is arranged above B1; B3 is arranged above B4; B6 is arranged above B5; B7 is arranged above B7; the skateboard ball joint mounting seats of the two skateboard assemblies (B) installed on the same module assembly (C) of the skateboard assembly Bi are staggered.

4. According to claim 1, a four-module eight-link redundant drive novel six-DOF parallel mechanism is characterized by: According to the specified trajectory planning of the dynamic platform (D) in the workspace, the kinematics and dynamics of the mechanism are solved, the optimal value of the driving force is solved, the positions of the six non-redundantly driven slide assemblies (B) are adjusted by position servo control, and the positions of the two redundantly driven slide assemblies (B) are adjusted by force servo control.

5. According to claim 1, a four-module eight-link redundant drive novel six-DOF parallel mechanism is characterized by: The slide plate assembly (B) is driven to move by a dual-motor dual-screw transmission method.

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