Hybrid processing robot based on kinematically redundant parallel mechanism

Abstract

The application relates to the field of robot technology, in particular to a hybrid processing robot based on a motion-redundant parallel mechanism, which comprises a fixed base, a movable base, a column and a motion-redundant parallel mechanism composed of two PRPU side branches and one PUPR middle branch. The end of the parallel mechanism is connected with a moving platform and a cutter, and the moving platform is provided with two rotating and one moving degrees of freedom. The moving along the X axis is realized through a guide rail pair between the movable base and the fixed base, and the moving along the Z axis is realized through a Z axis screw on the column, so that a five-degree-of-freedom hybrid system is formed. The application effectively avoids the singular configuration of the mechanism by introducing the motion redundancy, significantly increases the rotating capacity and the working space of the moving platform, has the advantages of high rigidity, high precision and high flexibility, and is suitable for efficient processing of complex parts.

Description

Technical Field

[0001] This invention relates to the field of robotics, specifically to a hybrid processing robot based on a motion redundancy parallel mechanism. Background Technology

[0002] Robots can be broadly classified into two categories based on their topological structure: serial mechanisms and parallel mechanisms. Serial mechanisms consist of a series of links connected in series via movable or revolute joints, while parallel mechanisms connect the moving and stationary platforms through multiple independent kinematic chains. Serial mechanisms are simple in structure, easy to control, and offer a large workspace, but they have poor rigidity, are prone to cumulative errors, and have low repeatability. They are currently mainly used in industrial automation production lines. Compared to serial mechanisms, parallel mechanisms offer advantages such as high rigidity, high precision, high load-bearing capacity, and good dynamic response, and are widely used in sorting and handling, motion simulation, surgical applications, and parts processing.

[0003] However, parallel mechanisms also have some drawbacks, such as small workspace, numerous singular configurations, and complex control. Researchers both domestically and internationally have discovered that motion redundancy can be used to improve these issues. A motion-redundant parallel mechanism refers to a mechanism whose degrees of freedom are greater than the number of independent motions output by the moving platform. This can be achieved by adding at least one driving joint to each motion branch. For a given moving platform pose, the poses of each branch of a motion-redundant parallel mechanism have infinitely many feasible solutions, but the driving force is unique and no internal forces are generated. Motion-redundant parallel mechanisms can not only avoid singularities and improve stiffness, but also increase the workspace and enhance other performance characteristics of the mechanism.

[0004] From a mechanistic perspective, existing hybrid machining robot configurations still cannot meet the demands for efficient machining of large parts. The main reasons are as follows: Core modules of existing hybrid machining robots, such as the Z3 spindle head (3-PRS parallel mechanism) and the 2PRU-PUR parallel mechanism, lack redundant degrees of freedom, have numerous singular configurations, and weak rotational capabilities, making them ill-suited for the large-area rotational workspace requirements of complex part machining. Furthermore, many core modules of hybrid machining robots currently in use, such as the Z3 parallel spindle head, are protected by patents abroad. Therefore, there is an urgent need to design a hybrid machining robot based on a motion-redundant parallel mechanism. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a hybrid processing robot based on a motion redundancy parallel mechanism.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a hybrid machining robot based on a motion redundancy parallel mechanism, comprising a fixed base, a movable base, a column, a central branch, two side branches, a moving platform, a cutting tool, a Z-axis lead screw, a Y-axis lead screw, and a trapezoidal protective shell; the fixed base is fixedly installed, the movable base is connected to the fixed base via a guide rail and can move along the X-axis; the column is vertically mounted on the movable base, the Z-axis lead screw is mounted on the column and can drive the connecting components to move along the Z-axis; the ends of the central branch and the two side branches are all connected via the Y-axis. The lead screw is connected to the trapezoidal protective shell; the lower ends of the two side branches are connected to the moving platform through Hooke pairs, and the lower end of the middle branch is connected to the moving platform through a revolute joint; the tool is mounted on the electric spindle, and the electric spindle is fixed to the moving platform; the middle branch and the two side branches constitute a PRPU-PUPR motion redundant parallel mechanism, which provides three degrees of freedom for the moving platform, superimposed with the degree of freedom of movement along the X-axis provided by the movable base and the degree of freedom of movement along the Z-axis provided by the Z-axis lead screw, together forming a five-degree-of-freedom hybrid machining robot.

[0007] In some embodiments, the motion redundancy parallel mechanism is composed of two identical PRPU-type side branches and a PUPR-type middle branch arranged symmetrically.

[0008] In some embodiments, the intermediate branch, from its connection with the Y-axis lead screw to its connection with the moving platform, sequentially includes a sliding joint, a Hooke joint, a sliding joint, and a revolute joint.

[0009] In some embodiments, each of the side branches, from its connection with the Y-axis lead screw to its connection with the moving platform, sequentially includes a sliding joint, a rotary joint, a sliding joint, and a Hooke joint.

[0010] In some embodiments, the axes of the sliding joints at the ends of the two side branches and the middle branch and the Y-axis lead screw are coplanar and horizontally arranged; the axes of the rotating joints at the front end of the middle branch and the moving platform are parallel to each other and perpendicular to the Z-direction axis of the Hooke joints at the connection between the side branches and the moving platform; the centers of the Hooke joints at the front ends of the two side branches and the center of the rotating joints at the front end of the middle branch form an isosceles triangle.

[0011] In some embodiments, in the intermediate branch, the axis of the revolute joint at the front end of the link is parallel to the X-axis of the Hooke joint at the end, and perpendicular to the axis of the prismatic joint on the link.

[0012] In some embodiments, the motion redundancy parallel mechanism provides the moving platform with three degrees of freedom: rotational degree of freedom about the X-axis, rotational degree of freedom about the Y-axis, and translational degree of freedom along the Y-axis.

[0013] In some embodiments, the Z-axis lead screw is connected to the trapezoidal protective shell and is used to drive the motion redundant parallel mechanism to move along the Z-axis.

[0014] In some embodiments, the movable base is connected to the fixed base via guide rails to provide the hybrid processing robot with the degree of freedom to move along the X-axis.

[0015] In some embodiments, the sliding pairs on each branch are drive pairs, and the driving method is ball screw drive or hydraulic drive.

[0016] Compared with existing technologies, the beneficial effects of this invention are: combining the advantages of serial and parallel robots, and through in-depth research on hybrid machining robots, the hybrid machining robot proposed in this invention possesses motion redundancy characteristics, high machining speed and precision, large workspace, and high flexibility. This hybrid robot has significant advantages in machining complex parts with large cutting volumes, overcoming the shortcomings of serial and parallel robots, and enabling high-speed machining of complex parts within a large workspace.

[0017] Details of one or more embodiments of this application are set forth in the following drawings and description to make other features, objects and advantages of this application more readily apparent. The embodiments of this application will provide a detailed description and understanding of this application. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of a motion-hybrid processing robot. Figure 2 This is a schematic diagram of the structure of a motion-hybrid processing robot (excluding the outer shell); Figure 3 Explosion diagram of a motion redundant parallel mechanism (2PRPU-PUPR); Figure 4 A schematic diagram of the three-dimensional structure of the side branch (PRPU); Figure 5 This is a three-dimensional structural diagram of the intermediate branch (PUPR).

[0019] In the diagram: 1. Fixed base; 2. Movable base; 3. Outer shell; 4. Protective shell; 5. Column; 6. Z-axis lead screw; 7. Y-axis lead screw; 8. Middle branch; 9. Side branch; 10. Moving platform; 11. Cutting tool. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Traditional hybrid machining robot configurations suffer from problems such as lack of redundant degrees of freedom in core modules, numerous singular configurations, and weak rotational capabilities when efficiently machining large parts. These issues make it difficult to meet the demand for large-scale rotational workspaces in the machining of complex parts, and some core technologies are protected by foreign patents.

[0022] In this regard, such as Figures 1 to 5 As shown, this application proposes a hybrid machining robot based on a motion redundancy parallel mechanism, including a fixed base 1, a movable base 2, a column 5, a middle branch 8, two side branches 9, a moving platform 10, a cutting tool 11, a Z-axis lead screw 6, a Y-axis lead screw 7, and a trapezoidal protective shell 4; the fixed base 1 is fixedly installed, and the movable base 2 is connected to the fixed base 1 via a guide rail and can move along the X-axis; the column 5 is vertically installed on the movable base 2, and the Z-axis lead screw 6 is installed on the column 5 and can drive the connecting components to move along the Z-axis; the ends of the middle branch 8 and the two side branches 9 are all connected to the Y-axis lead screw 7. The trapezoidal protective shell 4 is connected; the lower ends of the two side branches 9 are connected to the moving platform 10 through Hooke joints, and the lower end of the middle branch 8 is connected to the moving platform 10 through a revolute joint; the tool 11 is mounted on the electric spindle, which is fixed to the moving platform 10; the middle branch 8 and the two side branches 9 constitute a 2PRPU-PUPR motion redundant parallel mechanism, which provides three degrees of freedom for the moving platform 10, superimposed with the degree of freedom of movement along the X-axis provided by the movable base 2 and the degree of freedom of movement along the Z-axis provided by the Z-axis lead screw 6, together forming a five-degree-of-freedom hybrid machining robot.

[0023] For ease of understanding, the following explains some key terms in this embodiment: A motion-redundant parallel mechanism refers to a mechanism whose number of degrees of freedom is greater than the number of independent motions output by the moving platform. It is achieved by adding at least one driving joint to each motion branch. Given the pose of the moving platform, each branch pose of this mechanism has multiple feasible solutions, but the driving force is unique and no internal forces are generated.

[0024] Hybrid machining robots are robot systems that combine the advantages of serial and parallel mechanisms. By combining different mechanisms, they aim to achieve a larger workspace, higher rigidity, and higher precision to adapt to complex machining tasks.

[0025] A Hooke joint, also known as a universal joint, is a type of connection that allows two axes to intersect in space and rotate relative to each other. It typically consists of two hinges, allowing rotation in two orthogonal directions.

[0026] A revolute joint is a type of connection that allows components to rotate relative to each other only about a fixed axis, providing one degree of rotational freedom.

[0027] The 2PRPU-PUPR kinematic redundancy parallel mechanism is a specific parallel mechanism configuration where P represents a prismatic joint, R represents a revolute joint, and U represents a Hooke joint. This configuration provides specific degrees of freedom for the moving platform through a specific combination of kinematic chains and introduces kinematic redundancy to improve mechanism performance.

[0028] Degrees of freedom refer to the number of independent movements a mechanism or its components can make in space. A five-degree-of-freedom hybrid machining robot means that its moving platform can be precisely controlled in five independent directions of motion.

[0029] This embodiment provides a hybrid machining robot based on a motion redundancy parallel mechanism. The main structure of the robot includes a shell, a fixed base, a movable base, a column, a middle branch, side branches, a moving platform, a cutting tool, a Z-axis lead screw, a Y-axis lead screw, and a trapezoidal protective shell. The base is fixed to the ground, the column is vertically mounted on the movable base, the Z-axis lead screw is mounted on the column and correspondingly positioned to the movable base, the ends of the side branches and the middle branch are connected to the trapezoidal protective shell via the Y-axis lead screw, the lower ends of the side branches are connected to the moving platform via a Hooke pair, and the lower end of the middle branch is connected to the moving platform via a revolute joint. The cutting tool is mounted on an electric spindle, which is fixed to the moving platform via a bushing.

[0030] Side branches (see) Figure 4 The system includes a first sliding joint, a first sliding joint slider 12, a first telescopic outer rod 13, a first telescopic inner rod 14, and a first Hooke hinge 15, which are sequentially connected between the Y-axis lead screw and the moving platform. The first sliding joint slider 12 mates with the first sliding joint guide rail fixed on the Y-axis lead screw to form a first sliding joint. The first sliding joint slider 12 mates with the through hole of the first telescopic outer rod 13 to form a first rotating joint. The first telescopic inner rod 14 mates with the first telescopic outer rod 13 to form a second sliding joint. The axis of the first rotating joint is parallel to the axis of the second rotating joint. (Note: The branch structures on both sides of this mechanism are the same, so only one branch structure is described.) Middle branch (see Figure 5 It includes a third sliding joint, a third sliding joint slider 16, a third telescopic outer rod 17, a third telescopic inner rod 18, and a fourth rotary joint 19, which are sequentially connected between the Y-axis lead screw and the moving platform. The third sliding pair slider 16 cooperates with the third sliding pair guide rail fixed on the Y-axis lead screw to form the third sliding pair. The third sliding pair slider 16 cooperates with the through hole of the third telescopic outer rod 17 to form the third rotating pair. The third telescopic inner rod 18 cooperates with the third telescopic outer rod to form the fourth sliding pair.

[0031] The first rotating shaft axis connecting the third rotating joint and the outer rod 17 of the third telescopic rod is perpendicular to the axis of the third rotating joint and perpendicular to the axis of the fourth sliding joint. The axes of the first sliding joints of the two side branches are parallel to the axis of the first sliding joint of the middle branch, and the first revolute joints of the two side branches are parallel. The axis of rotation of the first Hooke hinge of the middle branch is perpendicular to the axis of rotation of the first pivot joint of the side branch.

[0032] This application effectively solves the problems of numerous singular configurations and weak rotational capabilities in traditional hybrid machining robots by introducing a motion-redundant parallel mechanism as the core module. This five-DOF hybrid machining robot can provide a larger workspace for posture rotation, thereby adapting to the high-efficiency machining requirements of complex and large parts and improving machining flexibility and precision. In some of the above embodiments, a hybrid machining robot based on a kinematic redundancy parallel mechanism is proposed, which provides three degrees of freedom for the moving platform 10. However, if the composition and arrangement of this kinematic redundancy parallel mechanism lack a clear definition, it may lead to problems such as complex kinematic analysis, unstable dynamic performance, high manufacturing and assembly difficulty, and difficulty in ensuring high-precision motion control during actual operation.

[0033] In this regard, this application further proposes that the motion redundancy parallel mechanism is composed of two identical PRPU-type side branches 9 and a PUPR-type middle branch 8 arranged symmetrically.

[0034] Specifically, the PRPU-type side branch 9 and the PUPR-type intermediate branch 8 are two specific kinematic chain configurations that constitute a kinematic redundancy parallel mechanism. Here, P represents a prismatic joint, typically a joint that provides translational freedom in one direction, such as a linear guide or slider mechanism; R represents a revolute joint, typically a joint that provides rotational freedom about an axis, such as a hinge or bearing connection; and U represents a Hooke joint, a universal joint that provides two mutually perpendicular rotational degrees of freedom. By connecting these basic kinematic joints in series according to the order PRPU and PUPR, branches with specific kinematic characteristics are formed, which together support and drive the motion platform 10. This specific configuration choice is based on a comprehensive consideration of the requirements for the mechanism's degrees of freedom, workspace, stiffness, and kinematic redundancy characteristics. The two side branches 9 have identical structures, meaning they are consistent in terms of geometry, kinematic joint type, kinematic joint arrangement, and material properties. This design ensures a high degree of consistency in the kinematic and dynamic responses of the two side branches 9, thereby avoiding motion incoordination or uneven force distribution caused by structural differences. Symmetrical arrangement refers to the geometric symmetry between the two side branches 9 and the central axis of the middle branch 8 or the entire mechanism. For example, the middle branch 8 can be located on the center line of the two side branches 9, and the connection points of each branch with the moving platform 10 form a symmetrical geometric configuration. This symmetrical design helps the mechanism maintain good balance during operation, reduces off-center loads, and thus improves the overall stiffness and stability of the mechanism. At the same time, the symmetrical structure simplifies the kinematic and dynamic modeling of the mechanism, facilitating the design and implementation of the control system.

[0035] The above technical solution clarifies that the motion-redundant parallel mechanism consists of two identical PRPU-type side branches 9 and one PUPR-type middle branch 8 arranged symmetrically. This effectively solves the problems of motion performance, stability, and manufacturing / assembly complexity caused by unclear mechanism structures. Specifically, the two identical side branches 9 ensure the consistency of the mechanism's kinematic and dynamic characteristics, avoiding motion incoordination and uneven force distribution caused by structural differences, thereby improving the overall motion accuracy and reliability of the mechanism. Simultaneously, the symmetrical arrangement makes the force distribution more balanced during operation, significantly enhancing the mechanism's stiffness and stability, and reducing vibration and deformation, which is crucial for high-precision machining in processing robots. Furthermore, this standardized and symmetrical design greatly simplifies the manufacturing, assembly, and maintenance processes of the mechanism, reduces production costs, and facilitates the development of kinematic and dynamic analysis and control algorithms, thus improving the overall performance and practicality of the hybrid processing robot.

[0036] In some embodiments described above in this application, a motion-redundant parallel mechanism is proposed, consisting of two identical PRPU-type side branches 9 and a PUPR-type intermediate branch 8 arranged symmetrically. However, in the actual construction of the PUPR-type intermediate branch 8, the precise configuration of its internal joints is crucial to ensuring the motion performance, stiffness, and avoiding singular configurations of the mechanism. Improper joint sequence design may lead to restricted motion or increased control complexity.

[0037] In this regard, this application further proposes that the intermediate branch 8, from the connection point with the Y-axis lead screw 7 to the connection point with the moving platform 10, includes, in sequence, a sliding joint, a Hooke joint, a sliding joint, and a rotary joint.

[0038] The intermediate branch 8 is a core component of the parallel mechanism in the hybrid machining robot. Together with the two side branches 9, it supports and drives the moving platform 10. Its structure and motion characteristics directly affect the degrees of freedom, workspace, and stiffness of the entire parallel mechanism. The connection point of the Y-axis lead screw 7 is the starting point of the motion chain of the intermediate branch 8, typically achieved through a connector that transmits the linear motion of the Y-axis lead screw 7 to the first joint of the intermediate branch 8. The connection point of the moving platform 10 is the ending point of the motion chain of the intermediate branch 8. Through this connection point, the motion of the intermediate branch 8 is transmitted to the moving platform 10, and specific degrees of freedom of the moving platform 10 are restricted or provided.

[0039] The prismatic joint allows relative linear movement between components along an axis. In parallel mechanisms, it is often used to provide drive or restrict translation in a specific direction, and its implementation can include guide rails, linear bearings, etc. The Hooke joint allows relative rotation between components about two mutually perpendicular axes, providing two rotational degrees of freedom. It is usually composed of two hinges whose axes are perpendicular to each other and intersect at a point. The revolute joint allows relative rotation between components about an axis, providing one rotational degree of freedom. It is usually implemented by bearings, pins, etc. This specific joint sequence (PUPR) defines the kinematic characteristics of the intermediate branch 8, where the first prismatic joint is usually connected to the drive end of the Y-axis lead screw 7, providing translation in a certain direction; subsequent Hooke joints and prismatic joints allow the intermediate branch 8 to perform complex posture adjustments and extensions in space; the last revolute joint is connected to the moving platform 10, providing the moving platform 10 with rotational degrees of freedom about a specific axis.

[0040] Through the above technical solution, the kinematic chain of the intermediate branch 8 is clearly defined as including, in sequence, a prismatic joint, a Hooke joint, a prismatic joint, and a revolute joint from the connection point of the Y-axis lead screw 7 to the connection point of the moving platform 10. This application can accurately construct a PUPR-type intermediate branch 8. This specific joint sequence design allows the intermediate branch 8 to provide the necessary degrees of freedom of motion while effectively enhancing the rigidity of the mechanism and helping to avoid singular configurations in the workspace. This structure ensures that the intermediate branch 8 can stably and accurately transmit driving force, thereby providing reliable support and motion control for the moving platform 10, and thus improving the motion accuracy and machining stability of the entire hybrid machining robot. The aforementioned hybrid machining robot proposes a structure based on a motion-redundant parallel mechanism, which consists of two identical PRPU-type side branches 9 and a PUPR-type intermediate branch 8 arranged symmetrically. However, the specific kinematic chain configuration of the PRPU-type side branches 9, including the arrangement order and type of their internal joints, is not yet clear. This may lead to difficulties in accurately achieving the required motion characteristics and redundancy in actual design and control, thus affecting the accuracy and stability of the machining robot.

[0041] In this regard, this application further proposes that each side branch 9, from the connection point with the Y-axis lead screw 7 to the connection point with the moving platform 10, sequentially includes a sliding joint, a rotary joint, a sliding joint, and a Hooke joint.

[0042] Specifically, a prismatic joint is a joint that enables linear relative movement between components in a single direction. In mechanical systems, prismatic joints typically consist of a guide rail, a slider, and a drive mechanism, such as a ball screw drive or a hydraulic drive. Their function is to provide precise linear displacement, ensuring smooth movement of moving parts along a predetermined path. For example, the function of a prismatic joint can be achieved by mounting a slider on a linear guide rail and driving it along the guide rail direction using a ball screw. A revolute joint is a joint that allows relative rotational movement between components about a single fixed axis. It typically consists of a pin, bearings, and connecting parts, providing one degree of rotational freedom. Revolute joints are widely used in robotic arms and mechanisms to change the direction or angle of links. For example, the function of a revolute joint can be achieved by a pin passing through holes in two links, supplemented by bearings to reduce friction. A Hooke joint, also known as a universal joint, is a joint that enables relative rotational movement between components in two mutually perpendicular axial directions. It typically consists of two fork-shaped parts and a cross shaft, capable of transmitting torque and allowing for large angular deviations. Hooke pairs are very useful in applications where power transmission is required while allowing for large angular variations, such as in automotive driveshafts. Their structural feature is the ability to provide two orthogonal rotational degrees of freedom, thus enabling complex spatial attitude adjustments.

[0043] By specifying that each side branch 9, from its connection with the Y-axis lead screw 7 to its connection with the moving platform 10, sequentially comprises a prismatic joint, a revolute joint, a prismatic joint, and a Hooke joint, this application provides a specific kinematic chain structure for the PRPU-type side branch 9. This specific joint sequence design enables the side branch 9 to precisely realize its PRPU-type kinematic characteristics, providing one translational degree of freedom, one rotational degree of freedom, another translational degree of freedom, and two rotational degrees of freedom provided by a Hooke joint, thereby providing the moving platform 10 with the required three degrees of freedom (rotational degree of freedom about the X-axis, rotational degree of freedom about the Y-axis, and translational degree of freedom along the Y-axis). This explicit kinematic chain structure helps simplify mechanism design, improves the accuracy of motion control, and ensures that in a kinematically redundant parallel mechanism, the side branch 9 can stably and reliably support and drive the moving platform 10, thereby improving the machining accuracy and dynamic performance of the entire hybrid machining robot. In some embodiments described above in this application, a hybrid machining robot based on a motion-redundant parallel mechanism is proposed. This mechanism consists of two identical PRPU-type side branches 9 and a PUPR-type middle branch 8 arranged symmetrically, with the kinematic pair sequence within each branch clearly defined. However, in practical applications, if the spatial geometric relationship between the connection points of each branch of the parallel mechanism and the Y-axis lead screw 7 and the moving platform 10 is not precisely defined, it may lead to undesirable coupled motion, insufficient stiffness, or limited workspace during the mechanism's movement, thereby affecting machining accuracy and stability.

[0044] In response, this application further proposes the aforementioned hybrid machining robot, wherein the axes of the sliding joints at the ends of the two side branches 9 and the middle branch 8 connected to the Y-axis lead screw 7 are coplanar and horizontally arranged; the axes of the rotating joints at the front end of the middle branch 8 connected to the moving platform 10 are parallel to each other and perpendicular to the Z-direction axis of the Hooke joints at the connection between the side branches 9 and the moving platform 10; the centers of the Hooke joints at the front ends of the two side branches 9 and the center of the rotating joints at the front end of the middle branch 8 form an isosceles triangle.

[0045] Specifically, the coplanar and horizontal arrangement of the axes of the sliding pairs at the connections between the ends of the two side branches 9 and the middle branch 8 and the Y-axis lead screw 7 refers to the motion axes of the sliding pairs at the connection points of the three branches (two side branches 9 and one middle branch 8) of the parallel mechanism and the Y-axis lead screw 7. These sliding pairs are the initial kinematic pairs of each branch, and they collectively determine the drive input of the parallel mechanism in the Y-axis direction. Setting the axes of these sliding pairs to be coplanar and horizontal means that their motion directions are all on the same horizontal plane and parallel to each other. This arrangement simplifies the drive control in the Y-axis direction, ensures the synchronous or coordinated movement of the three branches in the Y-axis direction, helps maintain the overall stability of the mechanism, and lays the foundation for subsequent motion decoupling. It avoids the complex spatial constraints and additional torques caused by non-coplanar or non-horizontal axes, thereby improving the motion accuracy and stiffness of the mechanism.

[0046] The axes of the revolute joint at the connection point of the intermediate branch 8 and the moving platform 10 are parallel to each other and perpendicular to the Z-axis of the Hooke joint at the connection point of the side branch 9 and the moving platform 10. This describes the geometric relationship of the output end of the parallel mechanism, i.e., the joints at the connection points of each branch and the moving platform 10. The end of the intermediate branch 8 connects to the moving platform 10 via a revolute joint whose axes are constrained to be parallel. Simultaneously, the ends of the two side branches 9 connect to the moving platform 10 via Hooke joints, which typically consist of two mutually perpendicular revolute joints; here, the Z-axis of one of the revolute joints is specifically mentioned. This specific axis arrangement is key to achieving specific degrees of freedom for the moving platform 10 (e.g., rotation about the X and Y axes and movement along the Y axis). By making the axis of the revolute joint of the intermediate branch 8 perpendicular to the Z-axis of the Hooke joint of the side branch 9, the motion of the moving platform 10 can be effectively decoupled, enabling it to independently rotate about the X and Y axes and move along the Y axis. This geometric constraint helps eliminate unwanted coupled motions, improving the motion accuracy and control performance of the mechanism.

[0047] The Hooke subcenters at the front ends of the two side branches 9 and the revolute subcenter at the front end of the middle branch 8 form an isosceles triangle, describing the relative positional relationship of the three connection points on the moving platform 10 (the Hooke subcenters of the two side branches 9 and the revolute subcenter of the middle branch 8). This isosceles triangular layout signifies the symmetry of the connection points between the moving platform 10 and the parallel mechanism. This symmetry is crucial for ensuring a balance in the kinematic characteristics and mechanical performance of the mechanism. It helps maintain good force transmission and stiffness distribution during the movement of the moving platform 10, reducing off-center loading and vibration caused by asymmetrical structures, thereby improving machining stability and accuracy. Simultaneously, the isosceles triangular geometry simplifies the kinematic analysis and control algorithms of the mechanism.

[0048] Through the above technical solution, the axes of the sliding joints at the ends of the two side branches 9 and one middle branch 8, which connect to the Y-axis lead screw 7, are set to be coplanar and horizontally arranged. This ensures good coordination and stability of the drive input in the Y-axis direction of the parallel mechanism, effectively avoiding complex motion coupling caused by inconsistent axes. Simultaneously, the axes of the revolute joints at the front end of the middle branch 8, which connect to the moving platform 10, are parallel to each other and perpendicular to the Z-axis of the Hooke joints at the connections of the side branches 9 and the moving platform 10. This precise orthogonal arrangement of joint axes effectively decouples the motion of the moving platform 10, enabling more precise and independent control in its three degrees of freedom: rotation around the X-axis, rotation around the Y-axis, and movement along the Y-axis, significantly reducing errors caused by motion coupling. Furthermore, the centers of the Hooke joints at the front ends of the two side branches 9 and the center of the revolute joints at the front end of the middle branch 8 form an isosceles triangle. This symmetrical connection point layout further optimizes the force distribution and stiffness characteristics of the moving platform 10, enhancing the mechanism's resistance to eccentric loads and overall stability during processing. In summary, the introduction of these geometric constraints greatly improves the motion accuracy, control performance, and structural stability of hybrid machining robots, enabling them to complete high-precision machining tasks more efficiently and reliably. In some embodiments described above in this application, a hybrid machining robot is proposed to provide three degrees of freedom to the moving platform 10 through a motion-redundant parallel mechanism, and combined with the X-axis and Z-axis translational degrees of freedom, to form a five-degree-of-freedom machining capability. However, when realizing the internal linkage movement of the intermediate branch 8 of this parallel mechanism, if there is a lack of precise geometric constraints between its internal joint axes, it may lead to instability and decreased accuracy in motion transmission, affecting the motion trajectory control of the moving platform 10, and thus making it difficult to guarantee machining accuracy.

[0049] In this regard, this application further proposes that in the intermediate branch 8, the axis of the rotating joint at the front end of the connecting rod is parallel to the X-axis of the Hooke joint at the end, and perpendicular to the axis of the sliding joint on the connecting rod.

[0050] Specifically, in intermediate branch 8, the revolute joint at the front end of the link refers to the revolute joint connecting intermediate branch 8 and moving platform 10, and its axis defines the rotational direction of this connection point. The end Hooke joint is a Hooke joint inside intermediate branch 8, which has two mutually perpendicular axes of rotation, one of which is designated as the X-axis. By setting the axis of the revolute joint at the front end of the link and the X-axis of the end Hooke joint to be parallel to each other, the kinematic coordination of these two key rotary joints in a specific direction is ensured. This parallel relationship helps to form a defined plane of rotation within intermediate branch 8, thereby simplifying kinematic analysis and providing a basis for precise attitude control of moving platform 10. For example, this can be achieved by precisely aligning the mounting bases of these two joints during the design phase.

[0051] Meanwhile, the prismatic joint on this link refers to the prismatic joint inside the intermediate branch 8, whose axis defines the linear direction of the link. By setting the axes of the aforementioned parallel revolute joints (i.e., the axis of the revolute joint at the front end of the link and the X-axis axis of the Hooke joint at the end) perpendicular to the axis of the prismatic joint, a precise orthogonal relationship is established for the kinematic chain inside the intermediate branch 8. This perpendicular relationship ensures that the translational and rotational motions of the intermediate branch 8 are geometrically decoupled, meaning that the linear motion of the prismatic joint will not introduce unintended rotational components, and vice versa. This is crucial for eliminating parasitic motion and improving the purity of motion transmission, thereby ensuring the precise realization of the moving platform 10's translational degree of freedom in the Y-axis direction and its rotational degrees of freedom around the X and Y axes. For example, this can be achieved by mounting the guide rail direction of the prismatic joint at a 90-degree angle to the axis direction of the revolute joint.

[0052] Through the above technical solution, the axis of the revolute joint at the front end of the connecting rod inside the intermediate branch 8 is parallel to the X-axis of the Hooke joint at the end, and these axes are perpendicular to the axis of the prismatic joint on the connecting rod, thus establishing clear and decoupled geometric constraints in the internal kinematic chain of the intermediate branch 8. This precise axis configuration effectively avoids unnecessary coupled motion or parasitic degrees of freedom generated by the intermediate branch 8 during movement, greatly improving the stability and accuracy of motion transmission. Because the motion of the intermediate branch 8 is more controllable and precise, its support and driving effect on the moving platform 10 is also more stable, thus ensuring that the moving platform 10 can achieve high-precision trajectory tracking and attitude control when performing machining tasks. This has a significant improvement effect on the overall machining accuracy and repeatability of the hybrid machining robot, especially in scenarios requiring fine operation and complex surface machining, effectively solving the machining error problem caused by inaccurate internal joint movements. In response, this application proposes a hybrid machining robot, in which a motion-redundant parallel mechanism serves as the core execution component, providing three key degrees of freedom for the moving platform 10. However, without clearly defining the specific types of these three degrees of freedom, ambiguity may arise in robot kinematic modeling, trajectory planning, and actual machining control, affecting machining accuracy and efficiency, and making it difficult to fully leverage the advantages of the parallel mechanism.

[0053] This application further clarifies that the motion redundancy parallel mechanism provides three degrees of freedom for the moving platform 10, including: rotational degree of freedom about the X-axis, rotational degree of freedom about the Y-axis, and translational degree of freedom along the Y-axis direction.

[0054] This motion-redundant parallel mechanism, through its specific configuration and joint arrangement, endows the moving platform 10 with specific motion capabilities. These three degrees of freedom are the motions that this parallel mechanism can achieve independently of external additional degrees of freedom (such as X-axis and Z-axis movement). Together, they determine the attitude adjustment and local position movement capabilities of the moving platform 10 in space, which is crucial for realizing complex surface machining and multi-angle operation.

[0055] The rotational degree of freedom about the X-axis refers to the ability of the moving platform 10 to rotate around its own or a reference coordinate system's X-axis. This rotational capability allows the tool 11 mounted on the moving platform 10 to change its tilt angle in the YZ plane, thereby adapting to the machining requirements of different inclined or curved surface features. For example, during milling or drilling, by adjusting the rotation angle of the tool 11 around the X-axis, the sidewall of the workpiece can be machined, or a chamfering operation can be performed at a specific angle. This degree of freedom is typically achieved through the synergistic action of Hooke's joints or revolute joints at the connection points between the ends of each branch in a parallel mechanism and the moving platform 10.

[0056] The rotational degree of freedom about the Y-axis refers to the ability of the moving platform 10 to rotate around its own or a reference coordinate system's Y-axis. This rotational capability allows the tool 11 to change its tilt angle in the XZ plane, further enhancing the flexibility and adaptability of machining. For example, when machining workpieces with complex geometries, by rotating about the Y-axis, the tool 11 can approach the machining area from different sides, avoiding interference and optimizing cutting conditions. This degree of freedom also relies on the ingenious configuration and coordinated movement of the Hooke pairs or revolute pairs at the connection points between the ends of each branch in the parallel mechanism and the moving platform 10.

[0057] The degree of freedom of movement along the Y-axis refers to the ability of the moving platform 10 to translate linearly along the Y-axis. This translational capability enables the tool 11 to achieve precise feed or positioning in the forward and backward directions, thereby allowing for deep machining or scanning machining along the Y-axis of the workpiece without changing the X and Z-axis positions or the tool orientation. This degree of freedom is typically achieved through the coordinated extension and retraction of the sliding pairs within each branch of the parallel mechanism. By precisely controlling the length changes of these sliding pairs, smooth movement of the moving platform 10 in the Y-axis direction can be achieved.

[0058] By clearly defining the three degrees of freedom provided to the moving platform 10 by the redundant parallel mechanism—specifically, rotational freedom around the X-axis, rotational freedom around the Y-axis, and translational freedom along the Y-axis—this application eliminates ambiguity in robot kinematics analysis and control strategy formulation. This explicit definition of degrees of freedom allows the robot controller to more accurately calculate the pose of the moving platform 10, thereby achieving precise positioning and orientation of the tool 11. Specifically, the rotational degrees of freedom around the X-axis and Y-axis endow the tool 11 with the ability to adjust its posture in two orthogonal planes, greatly expanding the machining angle and range, enabling the robot to efficiently complete machining tasks involving complex curved surfaces, inclined planes, and multi-angle features. Simultaneously, the translational degree of freedom along the Y-axis ensures precise feed and positioning of the tool 11 in the Y-direction, further improving machining depth and accuracy. Combined with the X-axis movement degree of freedom provided by the movable base 2 and the Z-axis movement degree of freedom provided by the Z-axis lead screw 6, this clear three-degree-of-freedom configuration enables the entire five-degree-of-freedom hybrid machining robot to achieve more flexible, precise and efficient machining operations, significantly improving the robot's versatility and machining quality. In some embodiments described above in this application, the hybrid machining robot provides the degree of freedom of movement along the Z-axis via the Z-axis lead screw 6. However, during its implementation, ensuring that the Z-axis lead screw 6 can effectively drive the entire motion-redundant parallel mechanism to move as a whole along the Z-axis direction to achieve the five degrees of freedom required by the robot is a technical detail that needs to be clarified. If the Z-axis lead screw 6 only drives local components, it may lead to uncoordinated Z-axis movement of the motion-redundant parallel mechanism or failure to achieve overall Z-axis displacement, thereby affecting the working range and accuracy of the machining robot.

[0059] In this regard, this application further proposes that the Z-axis lead screw 6 is connected to the trapezoidal protective shell 4 and is used to drive the motion redundant parallel mechanism to move along the Z-axis direction.

[0060] Specifically, the Z-axis lead screw 6 is a precision transmission component that converts rotary motion into linear motion. It typically consists of a lead lever, a nut, and balls, providing high-precision, high-rigidity linear displacement. The trapezoidal protective shell 4 serves as the upper connecting structure of the motion redundancy parallel mechanism in the hybrid machining robot. It is connected to the ends of the middle branch 8 and the two side branches 9 via the Y-axis lead screw 7, bearing and transmitting the driving force in the Y-axis direction. The connection between the Z-axis lead screw 6 and the trapezoidal protective shell 4 is usually achieved by rigidly fixing the nut portion of the Z-axis lead screw 6 (or via a connecting seat) to the corresponding structure of the trapezoidal protective shell 4. This connection method ensures that the linear motion of the Z-axis lead screw 6 can be directly and effectively transmitted to the trapezoidal protective shell 4.

[0061] Since the trapezoidal protective shell 4 is the common upper connection point of all branches (middle branch 8 and two side branches 9) of the motion-redundant parallel mechanism, when the Z-axis lead screw 6 drives the trapezoidal protective shell 4 to move along the Z-axis, the entire motion-redundant parallel mechanism, including all its branches and the moving platform 10 supported by these branches, will be displaced synchronously along the Z-axis as a whole. This overall movement ensures that the internal kinematic relationships and structural integrity of the parallel mechanism are maintained when it performs Z-axis motion, thus providing a stable and reliable Z-axis degree of freedom for the hybrid machining robot.

[0062] By directly connecting the Z-axis lead screw 6 to the trapezoidal protective shell 4 and utilizing it to drive the motion redundant parallel mechanism to move along the Z-axis, this application effectively solves the integration problem of Z-axis motion and the overall motion of the parallel mechanism. This connection method ensures that the linear driving force of the Z-axis lead screw 6 can be directly and stably transmitted to the entire parallel mechanism, enabling the parallel mechanism to perform precise displacement in the Z-axis direction as a whole. This not only simplifies the control of Z-axis motion and improves motion coordination, but also ensures that the hybrid machining robot can fully utilize the Z-axis degree of freedom, expand its workspace, and improve machining accuracy and stability, thereby achieving efficient and precise five-degree-of-freedom machining capabilities. In some embodiments described above in this application, the hybrid machining robot moves along the X-axis via a guide rail connection between the movable base 2 and the fixed base 1. However, for a complex hybrid machining robot system, how to clearly and effectively utilize this X-axis movement capability, making it an independent and controllable degree of freedom for the robot as a whole, thereby expanding its working range and improving its machining flexibility, requires further clarification and optimization.

[0063] To address this, this application further proposes that the movable base 2 is connected to the fixed base 1 via guide rails, providing the hybrid machining robot with the freedom to move along the X-axis. Specifically, the guide rail connection between the movable base 2 and the fixed base 1 can be, for example, a linear guide rail pair or a sliding guide rail pair, ensuring that the movable base 2 can achieve smooth and precise linear reciprocating motion on the fixed base 1. This connection method provides a unified moving platform along the X-axis for the entire upper structure supported by the movable base 2, including the column 5, the Z-axis lead screw 6, the motion redundant parallel mechanism, the moving platform 10, and the cutting tool 11. By precisely controlling the displacement of the movable base 2 through a drive mechanism (e.g., a ball screw or linear motor connected to the movable base 2), the overall translation of the hybrid machining robot in the X-axis direction can be achieved. This means that when the robot needs to process workpiece areas located at different X-axis positions, there is no need to readjust the workpiece position; simply by controlling the movement of the movable base 2, the entire processing unit can be moved to the target X-axis position, thereby expanding the robot's effective working range.

[0064] Through the aforementioned technical solution, the hybrid machining robot can obtain a clear and controllable overall degree of freedom of movement along the X-axis. This means that the robot can not only perform complex movements in a local space using its parallel mechanism, but also translate the entire working area along the X-axis by moving the movable base 2, thereby significantly expanding the robot's effective workspace. This design allows the robot to adapt to the machining needs of longer or wider workpieces, or to perform continuous machining on different areas of the workpiece without changing its position, greatly improving the flexibility and efficiency of machining. In addition, managing X-axis movement as an overall degree of freedom simplifies the robot's motion planning and control strategy, enabling the robot to complete multi-axis linkage machining tasks more efficiently. In the aforementioned hybrid machining robot, both the intermediate branch 8 and the side branch 9 of the motion redundancy parallel mechanism contain prismatic pairs. However, if the driving method of these prismatic pairs is not clearly defined, it may lead to difficulties in achieving precise motion control and stable machining performance during actual operation, thereby affecting the overall working accuracy and efficiency of the machining robot.

[0065] In response, this application further proposes that the sliding pairs on each branch are drive pairs, and the drive method is ball screw drive or hydraulic drive; from the initial stage, by controlling the movement of the six drive pairs, the three branches of the mechanism can generate redundant degrees of freedom, reduce the input singular configuration, increase the rotation angle of the moving platform, and improve the flexibility of the mechanism.

[0066] Specifically, the phrase "the sliding pairs on each branch are driven pairs" means that the sliding pairs contained in the middle branch 8 and the two side branches 9 are no longer simple passive connectors, but rather actuators capable of actively generating motion or force. These driven pairs, by receiving control signals, can precisely control their own displacement, thereby driving the entire branch and even the moving platform 10 to perform the desired motion. Setting them as driven pairs is the foundation for achieving precise motion control of parallel mechanisms.

[0067] When the drive method is ball screw drive, the drive system typically consists of a ball screw pair, a servo motor, and corresponding transmission connecting parts. The ball screw pair includes a screw with precision helical grooves and a nut with balls. The servo motor is connected to the screw via a coupling or other means, driving the screw to rotate. As the screw rotates, the nut moves linearly along the screw axis under the action of the balls. In the sliding pairs of each branch, the screw can be fixed to one component of the branch, while the nut is connected to another movable component. By precisely controlling the speed and angle of the servo motor, high-precision, high-rigidity linear displacement of the sliding pairs can be achieved. This drive method has advantages such as high transmission efficiency, high positioning accuracy, small backlash, good rigidity, and long service life, making it particularly suitable for applications requiring extremely high machining accuracy and repeatability.

[0068] When hydraulic drive is used, the drive system typically consists of a hydraulic pump, hydraulic cylinder, control valve, oil tank, and piping. The hydraulic pump pressurizes hydraulic oil and sends the high-pressure oil into the hydraulic cylinder through the control valve. Inside the hydraulic cylinder, the piston generates thrust under the action of the hydraulic oil, driving the piston rod to extend and retract, thus achieving linear motion. In the sliding joints of each branch, the cylinder body of the hydraulic cylinder can be fixed to one component of the branch, and the piston rod is connected to another movable component. By precisely controlling the flow and pressure of the hydraulic oil, precise displacement and force control of the sliding joint can be achieved. Hydraulic drives are characterized by high output force, fast response speed, high rigidity, easy stepless speed regulation, and strong shock resistance, making them suitable for applications requiring high loads, rapid response, and harsh working environments.

[0069] By explicitly designating the prismatic joints on each branch as drive joints and employing either ball screw drive or hydraulic drive, this application ensures precise and controllable motion of the motion-redundant parallel mechanism in the hybrid machining robot. Ball screw drive provides high-precision, high-rigidity, and low-backlash linear motion, significantly improving the positioning accuracy and repeatability of the moving platform 10, making it particularly suitable for tasks requiring extremely high machining precision. Hydraulic drive, on the other hand, provides powerful driving force and rapid response, enabling the robot to exhibit superior performance when handling heavy loads or machining scenarios requiring rapid attitude adjustments. This choice of drive methods allows the hybrid machining robot to flexibly select the appropriate drive scheme based on specific machining requirements, thereby effectively improving the robot's dynamic response and load capacity while ensuring machining accuracy, further optimizing the overall performance and machining efficiency of the entire five-degree-of-freedom hybrid machining robot.

[0070] The above embodiments merely illustrate several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

[0071] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A hybrid machining robot based on a motion redundancy parallel mechanism, characterized in that, It includes a fixed base (1), a movable base (2), a column (5), a middle branch (8), two side branches (9), a moving platform (10), a cutting tool (11), a Z-axis lead screw (6), a Y-axis lead screw (7), and a trapezoidal protective shell (4); the fixed base (1) is fixedly installed, the movable base (2) is connected to the fixed base (1) via a guide rail and can move along the X-axis; the column (5) is vertically installed on the movable base (2), the Z-axis lead screw (6) is installed on the column (5) and can drive the connecting parts to move along the Z-axis; the ends of the middle branch (8) and the two side branches (9) are connected to the trapezoidal protective shell (4) via the Y-axis lead screw (7). 4) Connected; the lower ends of the two side branches (9) are connected to the moving platform (10) through Hooke joints, and the lower end of the middle branch (8) is connected to the moving platform (10) through a revolute joint; the tool (11) is mounted on the electric spindle, and the electric spindle is fixed on the moving platform (10); the middle branch (8) and the two side branches (9) constitute a 2PRPU-PUPR motion redundant parallel mechanism, which provides three degrees of freedom for the moving platform (10), superimposed with the degree of freedom of movement along the X-axis provided by the movable base (2) and the degree of freedom of movement along the Z-axis provided by the Z-axis lead screw (6), together forming a five-degree-of-freedom hybrid machining robot.

2. The hybrid processing robot according to claim 1, characterized in that, The motion redundancy parallel mechanism consists of two identical PRPU-type side branches (9) and a PUPR-type middle branch (8) arranged symmetrically.

3. The hybrid processing robot according to claim 2, characterized in that, The intermediate branch (8) from the connection point with the Y-axis lead screw (7) to the connection point with the moving platform (10) includes, in sequence, a sliding joint, a Hooke joint, a sliding joint and a rotary joint.

4. The hybrid processing robot according to claim 2, characterized in that, Each of the side branches (9) from the connection with the Y-axis lead screw (7) to the connection with the moving platform (10) includes, in sequence, a sliding joint, a rotary joint, a sliding joint and a Hooke joint.

5. The hybrid processing robot according to claim 3 or 4, characterized in that, The axes of the sliding joints at the ends of the two side branches (9) and one middle branch (8) connected to the Y-axis lead screw (7) are coplanar and horizontally arranged; the axes of the rotating joints at the front end of the middle branch (8) connected to the moving platform (10) are parallel to each other and perpendicular to the Z-direction axis of the Hooke joint at the connection between the side branches (9) and the moving platform (10); the center of the Hooke joints at the front end of the two side branches (9) and the center of the rotating joints at the front end of the middle branch (8) form an isosceles triangle.

6. The hybrid processing robot according to claim 5, characterized in that, In the intermediate branch (8), the axis of the rotating joint at the front end of the connecting rod is parallel to the X-axis of the Hooke joint at the end, and perpendicular to the axis of the sliding joint on the connecting rod.

7. The hybrid processing robot according to claim 1, characterized in that, The motion redundancy parallel mechanism provides three degrees of freedom for the moving platform (10): rotational degree of freedom about the X-axis, rotational degree of freedom about the Y-axis, and translational degree of freedom along the Y-axis.

8. The hybrid processing robot according to claim 1, characterized in that, The Z-axis lead screw (6) is connected to the trapezoidal protective shell (4) and is used to drive the motion redundant parallel mechanism to move along the Z-axis.

9. The hybrid processing robot according to claim 1, characterized in that, The movable base (2) is connected to the fixed base (1) via a guide rail, which is used to provide the overall degree of freedom for the hybrid processing robot to move along the X-axis.

10. The hybrid processing robot according to any one of claims 1 to 4, characterized in that, The sliding pairs on each branch are drive pairs, and the drive method is ball screw drive or hydraulic drive.

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