Parallel tail end multi-degree-of-freedom mechanical arm

Abstract

The utility model discloses a parallel tail end multi-degree-of-freedom mechanical arm which comprises two groups of branch chains which are symmetrically arranged and fixed at two ends of a platform, each group of branch chains comprises a base, a first motor and a second motor are respectively arranged on two sides of the base, the first motor is connected with a first short connecting rod through a rocker arm, and the second motor is connected with a middle supporting piece. One end of the supporting piece is hung below the base through a support, the other end of the supporting piece is movably connected with the middle of the first long connecting rod, one end of the first long connecting rod is connected with the first short connecting rod, and the other end of the first long connecting rod is movably connected with the tail end platform. The other end of the second long connecting rod is movably connected with the tail end platform. According to the mechanical arm, the multi-degree-of-freedom parallel mechanical arm of the end effector can be achieved, and the problems that an existing parallel mechanical arm is complex in structure and high in control coupling degree, the degree of freedom of the end effector is limited, and installation and maintenance are difficult are solved.

Description

Technical Field

[0001] This utility model relates to robotic arms, specifically to a parallel end-effector multi-degree-of-freedom robotic arm. Background Technology

[0002] With the development of industrial automation and intelligent manufacturing, multi-degree-of-freedom robotic arms are widely used in aerospace, 3C assembly, medical, and service robotics fields. Parallel mechanisms, due to their high rigidity, high precision, and fast response speed, have significant advantages in high-speed grasping and precision operation.

[0003] Existing multi-degree-of-freedom parallel robotic arm structures mostly adopt triangular, Delta, or Stewart platform structures. Although they possess strong stability and control capabilities, they also have the following drawbacks:

[0004] (1) Complex structure and high control coupling: Some parallel mechanisms have asymmetrical structures, which leads to complex dynamic modeling and difficulty in implementing control algorithms;

[0005] (2) Limited space and poor flexibility: Most parallel structure end effectors have limited degrees of freedom and cannot be adjusted arbitrarily, which affects the task adaptability.

[0006] (3) Difficult installation and debugging, high maintenance costs: Traditional mechanisms require high installation accuracy, and the components are not easy to replace or maintain. Utility Model Content

[0007] Purpose of the utility model: The purpose of this utility model is to provide a parallel robotic arm with a simple structure, high degree of freedom, fast response, strong stability, and high control precision, which can realize multiple degrees of freedom of the end effector through a simple mechanism, so as to solve the problems of complex structure, high control coupling, limited degree of freedom of end effector, and difficult installation and maintenance of existing parallel robotic arms.

[0008] Technical Solution: The parallel end-effector multi-degree-of-freedom robotic arm of this utility model includes two symmetrically arranged branches. One end of each branch is respectively set at both ends of a fixed platform, and the other end is movably connected to the end-effector platform. Each branch includes a base, and a first motor and a second motor are respectively arranged on both sides of the base. The first motor is connected to a first short connecting rod through a rocker arm, and the second motor is connected to an intermediate support member. One end of the support member is suspended below the base through a bracket, and the other end is movably connected to the middle of a first long connecting rod. One end of the first long connecting rod is connected to the first short connecting rod, and the other end is movably connected to the end-effector platform. The base on the side corresponding to the second motor is connected to the second short connecting rod, and connected to the second long connecting rod through a connecting rod. The other end of the second long connecting rod is movably connected to the end-effector platform.

[0009] Furthermore, the first long link and the second long link are movably connected to the end platform via a slewing connector.

[0010] Furthermore, the end platform is equipped with tool mounting holes.

[0011] Furthermore, the support member is hollowed out.

[0012] This product addresses the problems of existing mechanisms by providing a symmetrical parallel robotic arm, with each side featuring a three-bar linkage. Its key technical solutions are as follows:

[0013] Mechanism structure: It includes two sets of symmetrically distributed parallel branches, each set of branches consisting of a servo motor, a linkage system and a rotary hinge.

[0014] Degrees of freedom and control: The end-effector can achieve at least three translational degrees of freedom and multiple orientation degrees of freedom (such as rotation about any axis) in space.

[0015] The servo motor controls the linkage angle, achieving precise position and attitude control of the end effector through inverse kinematics.

[0016] Symmetrical design:

[0017] All branches are symmetrically arranged, resulting in balanced forces and simplifying modeling and control algorithms.

[0018] Specific structural settings:

[0019] Fixed platform: The basic structure for mounting the entire robotic arm; symmetrically arranged support chains on both sides; can be fixed to a worktable or slide rail.

[0020] Base: Used to connect motors, support components, long and short connecting rods, etc.

[0021] Short link: One end is the active moving part; the other end is a rigid link that connects to the long link.

[0022] Connecting rod: Connects the short connecting rod to the long connecting rod to improve stability.

[0023] End platform: Supported and controlled by left and right branches; the structure is a lightweight rigid platform that can be equipped with tools, sensors or fixtures; it enables precise position and attitude control in space.

[0024] Tool mounting holes: located on the end effector platform; used to mount actuators such as grippers, cameras, spray heads, etc.

[0025] Rotary connector: The end of the long connecting rod is connected to the rotary connector, and the two long connecting rods on one side are connected to the same rotary connector.

[0026] Long links: The symmetrical mechanism on both sides has a total of four long links, which are ultimately connected to the same end platform; it supports the precise positioning of the entire end platform; it provides multi-degree-of-freedom rotation support; and it ensures the free adjustment of the attitude of the end effector.

[0027] Servo motor: It is used to rotate the short connecting rod.

[0028] Support component: Provides main support, connects to the motor at the base, and can rotate around the motor shaft.

[0029] The overall structure of the robotic arm includes a fixed platform and a branch chain assembly. The branches are arranged symmetrically and coupled only through the end-effector platform, forming a typical parallel mechanism.

[0030] 1. Symmetrical arrangement and connection relationship:

[0031] Two sets of branches are evenly distributed on both sides of the fixed platform, exhibiting mirror symmetry;

[0032] The end platform is located below the branches and is driven by the branches to form stable spatial support; it provides multi-degree-of-freedom mobility to ensure that the end platform can make arbitrary posture adjustments.

[0033] 2. Servo drive system

[0034] The driving source is a servo motor or stepper motor that is fixedly mounted on a fixed platform;

[0035] The motor drives the active linkage to change its angle or length through rotation or a slider structure;

[0036] The control system implements independent control of each motor, calculates the motor angle or displacement through a preset inverse kinematics algorithm, and drives the end effector to achieve the target pose.

[0037] 3. End-effector platform

[0038] The end platform is a rigid structure with multiple holes for mounting grippers, sensors, or tool modules;

[0039] The platform forms a closed kinematic chain through multiple branches, enabling it to operate in space:

[0040] 3D translation (X, Y, Z directions)

[0041] Attitude adjustment in two directions (rotation around the X and Y axes)

[0042] 4. Working principle

[0043] The control system calculates the angle that each drive motor should reach based on the target end pose;

[0044] The motor drives the short connecting rod to move, changing the position and attitude of the end platform through a parallel branch chain system;

[0045] Multi-degree-of-freedom adjustment is accomplished through the coordinated action of each branch, relying on changes in spatial configuration to achieve arbitrary twisting and movement at the end;

[0046] The system has a fast response, high stability, low coupling, and is easy to control and program.

[0047] 5. Special Improvement Points

[0048] This utility model introduces the following improvements and innovations based on the traditional parallel mechanism:

[0049] The branches adopt a symmetrical arrangement structure, which results in more balanced stress and greater rigidity.

[0050] The connection between the long connecting rod and the end platform has a rotational degree of freedom, which greatly improves the end-effector degree of freedom.

[0051] The modular design concept allows for expansion of the number of branches, enabling flexible adjustment of the degree of freedom and load capacity.

[0052] Motor control employs an embedded control system or a ROS platform control system, supporting advanced task scheduling and path planning.

[0053] The following is a breakdown:

[0054] High degree of freedom and flexible control: The end effector has multiple degrees of freedom, supporting arbitrary twisting and attitude adjustment to meet the needs of operation in complex environments.

[0055] Symmetrical structure enhances stability: Symmetrical design improves the stability and load-bearing capacity of the mechanism, balances the force, and reduces mechanical wear.

[0056] Simplified control and modeling: Symmetrical structures reduce the complexity of kinematic and dynamic modeling, and improve control accuracy and real-time performance.

[0057] Easy to maintain and modularly upgrade: High component independence facilitates fault diagnosis, maintenance, and system upgrades. Wide range of applications: Suitable for high-precision and high-dynamic scenarios, such as high-speed sorting, complex gripping, and precision assembly.

[0058] 1. High degree of freedom and flexible control

[0059] The end effector has at least three-dimensional translational degrees of freedom and multiple attitude rotational degrees of freedom, with a total degree of freedom of 6DoF or more, thus meeting the needs for arbitrary torsion and attitude adjustment in complex environments.

[0060] Corresponding technical improvements and reasoning analysis

[0061] The end-effector design incorporates a rotational degree of freedom at the connection point between the long connecting rod and the end platform, enabling the end platform to achieve not only three-axis motion but also multi-axis rotation in space.

[0062] Reasoning: In existing technologies, due to limitations in the number or type of hinges, it is often impossible to achieve arbitrary rotation while maintaining translation. The symmetrical multi-branch design of this utility model increases the local rotational degrees of freedom, thereby enabling the end platform to tilt, flip, or twist at any angle.

[0063] 2. Symmetrical multi-branch parallel layout

[0064] The horizontal projection shows at least two sets of symmetrically arranged parallel branches (left and right groups), each with multiple connecting rods.

[0065] When the parallel system arranged in this way reaches a certain posture at the end platform, the different branches move in coordination at different angles, thus realizing a more complex three-dimensional motion trajectory.

[0066] Reasoning: Compared with unilateral or asymmetric parallel configurations, symmetric parallel layouts are more flexible and redundant in terms of motion constraints, which can significantly improve the reachable attitude space of the end effector and ensure that each branch is within a reasonable working range under special attitudes, thereby achieving higher degrees of freedom while ensuring smooth motion and no dead zones.

[0067] 3. Symmetrical structure enhances stability

[0068] Based on the symmetrical parallel branch design, this invention can maintain the force balance of each branch when the robotic arm moves, thereby improving the rigidity of the mechanism, reducing vibration, reducing component wear and increasing load capacity.

[0069] Reasoning: Symmetrical distribution means that when the end effector is subjected to external loads or accelerated motion, the left and right branches will share the load in the same way, effectively avoiding deformation caused by overload of one side branch or excessive local stress. In existing asymmetrical parallel structures, one side branch often needs to bear a larger torque, which is prone to tilting, twisting and fatigue accumulation.

[0070] 4. Redundant rigid constraint links

[0071] In each branch, the middle link is composed of a four-bar linkage, which can always keep the link parallel to the platform or at a constant angle.

[0072] Reasoning: Parallelogram mechanisms inherently offer greater stability against external torques. When multiple such links are symmetrically arranged, the overall stiffness is significantly enhanced—resisting both radial loads and effectively suppressing torsional vibrations. In contrast, traditional simple "link-hinge" combinations are more prone to lateral vibration without a balancing mechanism. Through the aforementioned symmetrical design, this invention significantly improves stiffness and dynamic response performance compared to asymmetrical parallel mechanisms, greatly reducing vibration and deformation of the robotic arm during high-speed movement. Simultaneously, the balanced force distribution reduces localized wear and extends the service life of each joint and link.

[0073] 5. Simplify control and modeling

[0074] Due to its symmetrical structure and modular design, the kinematic and dynamic modeling of the parallel mechanism of this invention is simpler and clearer, and the implementation difficulty and computational load of the control algorithm are significantly reduced, thereby improving control accuracy and real-time performance.

[0075] Corresponding technical improvements and reasoning analysis

[0076] 6. Symmetrical geometric parameters

[0077] The left and right branches are geometrically symmetrical in the initial configuration (same link length, same link layout angle, same joint position).

[0078] Reasoning: In mathematical modeling, only one side of the branch needs to be modeled, and the corresponding parameters of the other side can be obtained directly through symmetric transformation (such as mirror mapping), thereby reducing the number of parameter variables and simplifying the solution process of the inverse kinematics equations. Existing asymmetric parallel mechanisms usually require modeling two or more sets of branches separately, resulting in a complex equation system and low solution efficiency.

[0079] 7. Simplify dynamic modeling

[0080] Because of the consistency of symmetrical forces and parameters, it is easy to construct dynamic equations in symmetrical matrix form by combining parameters such as mass and stiffness.

[0081] Reasoning: In a symmetrical parallel structure, the parameters of each branch are the same, and the inertia matrix and stiffness matrix have symmetrical characteristics. They can be solved directly in the form of an overall symmetrical matrix, reducing the number of iterations in numerical solutions. This results in a faster response and smaller error in the control system during high-speed motion and load changes.

[0082] 8. The control algorithm is simple to implement.

[0083] Due to symmetry, only one set of PID (or more advanced algorithm) parameter adjustment procedures needs to be implemented in the controller, which is applicable to all branches.

[0084] Reasoning: Compared to asymmetric parallel mechanisms that require independent parameter tuning for each link, development and maintenance only require tuning one set of parameters, which can be assigned to the other branch via mirror mapping. This reduces both the workload of development and debugging, and also reduces the potential for parameter tuning errors.

[0085] In summary, the symmetrical geometric and dynamic characteristics of this invention significantly reduce the modeling and control complexity of parallel mechanisms, enabling higher control accuracy and real-time performance under the same hardware conditions.

[0086] 1. Easy to maintain and modularly upgrade

[0087] The modular and symmetrical design proposed in this invention makes each component highly independent, facilitating disassembly, maintenance, and module replacement, thereby achieving system-level upgrades and significantly improving fault diagnosis efficiency.

[0088] 2. Corresponding technical improvements and reasoning analysis

[0089] Modular component design

[0090] Each branch (including short links, intermediate links, and long links) can be regarded as an individual module and connected to the fixed platform and the end platform through standardized interfaces.

[0091] Reasoning: When a single branch or joint fails, the same module can be directly removed and replaced without overall disassembly or parameter readjustment. Traditional parallel mechanisms often use a complex integrated frame, requiring extensive disassembly and reassembly for any local failure.

[0092] 3. Symmetry reduces the types of spare parts.

[0093] The left and right branch parameters and dimensions are exactly the same, so all branch modules are interchangeable in the spare parts inventory.

[0094] Reasoning: This design eliminates the need to maintain separate inventory of parts for each side or multiple locations, reducing inventory and maintenance costs. Furthermore, it eliminates concerns about installation errors caused by mixing left and right components during replacement. Through the aforementioned modular, standardized, and symmetrical design, this invention significantly simplifies subsequent maintenance processes, reduces production and maintenance costs, and provides convenience for industrial users to quickly deploy and iteratively upgrade in different application scenarios.

[0095] 4. Wide range of applications

[0096] This utility model of parallel robotic arm structure performs well in high-speed, high-precision and multi-working-condition environments, and can be used in various scenarios such as high-speed sorting, complex grasping, precision assembly, medical rehabilitation, and service robots.

[0097] Corresponding technical improvements and reasoning analysis

[0098] High rigidity and high-speed response

[0099] A symmetrical, simple four-bar linkage structure minimizes motion inertia while maintaining high rigidity. Reasoning: In high-speed sorting or precision assembly, the robotic arm needs high-speed reciprocating motion while maintaining high precision. The symmetrical parallel structure, combined with lightweight links, reduces inertial mass, while the ball joints allow for free attitude changes, ensuring smooth, vibration-free operation during reversals and turns.

[0100] Reasoning: After each joint of a symmetrical parallel mechanism receives the same motor command, the actual motion path is highly consistent due to the symmetrical structure, which reduces the propagation of unilateral errors; the symmetrical internal inertia matrix accelerates the convergence of the controller to the position error, so the repeated positioning accuracy is higher than that of an asymmetrical system.

[0101] 5. Multi-degree-of-freedom grasping and assembly capabilities

[0102] The end effector can rotate in any orientation, making it more flexible in confined spaces or when special tilting gripping of workpieces is required.

[0103] Reasoning: Traditional serial robotic arms may experience singular poses (dead zones) or excessive reach leading to spatial interference during end-effector posture switching. Parallel structures with ball joints cover most common postures, have no dead zones, and are particularly suitable for complex grasping and precision assembly tasks.

[0104] Modular integration adaptable to various operating conditions

[0105] The end effector can be quickly replaced with different actuators: high-precision clamps, force / torque sensors, vision cameras, spray heads, 3D printing heads, etc.

[0106] Reasoning: The end-effector platform of this utility model has reserved standard holes and through-hole interfaces, which can quickly install different working tools; the parallel structure ensures that different tools can still maintain the expected motion characteristics after assembly, expanding the application scenarios, such as medical rehabilitation can install adjustable wrist grippers, and service robots can install suction cups or soft grippers.

[0107] Compared with the prior art, the present invention has the following beneficial effects:

[0108] 1. High degree of freedom and flexible control: The end effector has multiple degrees of freedom, supporting arbitrary twisting and attitude adjustment to meet the needs of operation in complex environments.

[0109] 2. Symmetrical structure enhances stability: The symmetrical design improves the stability and load-bearing capacity of the mechanism, balances the force, and reduces mechanical wear.

[0110] 3. Simplified control and modeling: Symmetrical structures reduce the complexity of kinematic and dynamic modeling, and improve control accuracy and real-time performance.

[0111] 4. Easy to maintain and modularly upgrade: High component independence facilitates fault diagnosis, maintenance and system upgrades.

[0112] 5. Wide range of applications: Suitable for scenarios with high precision and high dynamic requirements, such as high-speed sorting, complex grasping, and precision assembly. Attached Figure Description

[0113] Figure 1 This is a schematic diagram of the overall structure of the device;

[0114] Figure 2 This is a schematic diagram of the branch chain structure on one side of this device;

[0115] Figure 3 This is a schematic diagram of the internal structure of the branch chain assembly of this device;

[0116] Figure 4 This is a schematic diagram of the end platform structure of this device. Detailed Implementation

[0117] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solutions of this utility model will be further described below.

[0118] The parallel end-effector multi-degree-of-freedom robotic arm of this embodiment includes two symmetrically arranged branches. One end of each branch is set at both ends of a fixed platform 1, and the other end is movably connected to an end-effector platform 6. Each branch includes a base 2. A first motor 13 and a second motor 14 are respectively arranged on both sides of the base 2. The first motor 13 is connected to a first short link 3 through a rocker arm 11. The second motor 14 is connected to an intermediate support member 12. One end of the support member 12 is suspended below the base 2 by a bracket, and the other end is movably connected to the middle of a first long link 9. One end of the first long link 9 is connected to the first short link 3, and the other end is movably connected to the end-effector platform 6. The base on the side corresponding to the second motor 14 is connected to a second short link 4, and connected to a second long link 10 through a connecting rod 5. The other end of the second long link 10 is movably connected to the end-effector platform 6.

[0119] The first long link 9 and the second long link 10 are movably connected to the end platform 6 via the slewing connector 8.

[0120] Set the tool mounting holes 7 on the end platform 6.

[0121] The support member 12 is hollowed out.

[0122] The above are merely preferred embodiments of this utility model and do not constitute any limitation on this utility model. Any equivalent substitutions or modifications made by those skilled in the art to the technical solutions and contents disclosed in this utility model without departing from the scope of the technical solutions of this utility model shall still fall within the protection scope of this utility model.

Claims

1. A parallel end multi-degree of freedom robot arm characterized by, It includes two groups of branched chains arranged symmetrically, one end of each group is arranged at the two ends of the fixed platform (1), and the other end is movably connected with the terminal platform (6), each group of branched chains includes a base (2), a first motor (13) and a second motor (14) are arranged on the two sides of the base (2), wherein the first motor (13) is connected with the first short connecting rod (3) through a rocker arm (11), the second motor (14) is connected with the intermediate support (12), one end of the support (12) is hung below the base (2) through a support, the other end is movably connected with the middle of the first long connecting rod (9), one end of the first long connecting rod (9) is connected with the first short connecting rod (3), and the other end is movably connected with the terminal platform (6), the base corresponding to the second motor (14) is connected with the second short connecting rod (4), the second long connecting rod (10) is connected through the connecting rod (5), and the other end of the second long connecting rod (10) is movably connected with the terminal platform (6).

2. The parallel-jointed multi-degree-of-freedom manipulator according to claim 1, wherein The first long connecting rod (9) and the second long connecting rod (10) are movably connected with the terminal platform (6) through the rotary connecting piece (8).

3. The parallel-jointed multi-degree-of-freedom manipulator according to claim 1, wherein The terminal platform (6) is provided with a tool mounting hole (7).

4. The parallel-jointed multi-degree-of-freedom manipulator according to claim 3, wherein The support (12) is hollow.

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