A parallel robotic arm

Abstract

This invention discloses a parallel robotic arm, comprising a base serving as the mounting foundation and an actuator located at the end for grasping objects. Two sets of motion chains, mainly composed of connecting rods, are mounted side-by-side on the base and connected to the actuator. The actuator is characterized in that it is vertically mounted on an actuator link, with both ends of the actuator link rotatably connected to the front ends of the two sets of motion chains. The invention also includes at least one self-rotating transmission mechanism attached to either motion chain, which drives the actuator link to perform synchronous rotational motion. This invention has the advantage of improving the range of motion of objects in a simpler manner.

Description

[0001] This application is a divisional application of the patent application number 202111029305.1, filed on 2021-09-03 entitled "A method for controlling the planar motion of an object using a robotic arm". Technical Field

[0002] This invention relates to the field of robotic arms for production or logistics, and specifically to a parallel robotic arm. Background Technology

[0003] In product manufacturing lines and logistics sorting systems, robotic arms are typically used to control the planar motion of items, thereby automating the production process. Common planar motion control robotic arms can be divided into two categories: serial and parallel. Among serial robotic arms, the most common structure is the articulated arm type, which uses two or three arms connected sequentially. A motor is mounted on the rear arm to drive the front arm, achieving motion control in one direction. The end effector, which holds the item in place, is mounted on the foremost arm. This multi-arm combination enables three-dimensional motion control of the end effector. During operation, the end effector picks up and holds the object to be moved, and then the motor controls the movement of each arm to achieve the movement control of the object.

[0004] This type of serial robotic arm has advantages such as simple and classic structure, stable and reliable control, large motion space, and fewer singularities (unreachable positions) within the workspace. However, the open-loop kinematic chain of the serial robotic arm makes the structure more complex and the motion control precision lower; moreover, each joint of the serial robotic arm requires a drive device, resulting in a larger weight and relatively greater inertia, which not only hinders control but also increases energy consumption and cost. Therefore, serial robotic arms are generally suitable for applications requiring the movement of large-mass and bulky objects, a large movement space, and lower requirements for positional accuracy.

[0005] For the movement control of objects that primarily translate on a fixed plane, have a small mass and volume, and require high positioning accuracy, parallel manipulators with planar motion control are more commonly used. Parallel manipulators typically employ parallel linkage mechanisms to form multiple sets of motion chains. Each set of motion chains drives the end effector to achieve translational control. They utilize closed-loop motion chains, where each set of component motion chains is independent, and errors in each chain cancel each other out. This significantly improves the motion accuracy of the mechanism while also increasing its overall rigidity and load-bearing capacity. Furthermore, due to the structural characteristics of parallel manipulators, their drive units can be mounted on the frame, reducing the added mass of components due to the drive unit, lightening the weight of the motion chains themselves, increasing movement speed, and reducing motion inertia.

[0006] However, parallel manipulators also have obvious drawbacks. Due to the large number of motion chains, their actual workspace is very small, and the singularity situation is complex. Furthermore, it is difficult to control the degree of freedom in the rotational direction, limiting the angular range that the object can be moved. Generally speaking, in parallel manipulators, to achieve movement control of an object in both the X and Y axes of the same plane, at least two sets of motion chains are usually required, with a minimum of five links connected to achieve control. For example, the two-degree-of-freedom spherical motion parallel mechanism disclosed in CN202011190090.7.

[0007] To achieve movement control of an object along the X, Y, and rotation axes on the same plane, three sets of parallel motion chains are typically required, with at least seven links needed to achieve control. Examples include a three-degree-of-freedom generalized spherical parallel mechanism disclosed in CN201910868664.2; a three-degree-of-freedom parallel mechanism for force feedback devices disclosed in CN201810973840.4; a three-degree-of-freedom parallel mechanism for remote-controlled hands disclosed in CN201810974973.3; and a three-degree-of-freedom parallel robot device disclosed in CN201921321553.1, etc.

[0008] Therefore, for those skilled in the art, in the field of parallel robotic arms controlling the planar motion of objects, how to achieve more degrees of freedom control of objects using fewer kinematic chains and links, and thus improve the flexibility of planar motion control of objects in a simpler way, has always been a research direction. Summary of the Invention

[0009] In view of the shortcomings of the prior art, the technical problem to be solved by the present invention is: how to provide a method for controlling the planar motion of an object using a robotic arm that can improve the range of motion of the object in a simpler way, and a parallel robotic arm.

[0010] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0011] A method for controlling the planar motion of an object using a robotic arm. In this method, an actuator grips and fixes the object, and then the actuator is controlled to achieve planar motion by two sets of motion chains, mainly composed of connecting rods, mounted on a base. The method is characterized by a self-rotating transmission mechanism attached to the motion chains, which drives the actuator to rotate synchronously while the two sets of motion chains control the planar motion of the actuator.

[0012] In this way, by controlling the planar motion of the actuator (with displacement along the X and Y axes) through two sets of kinematic chains of the parallel manipulator, the actuator is simultaneously rotated synchronously by a self-rotating transmission mechanism attached to the kinematic chains. This allows for further orientation adjustment of the object during grasping and translation, adding a degree of freedom for rotation along the Z axis. Therefore, the directional control range of the object's planar movement is greatly improved. Furthermore, this method combines the advantages of both series and parallel manipulators. Since this method is mainly based on two sets of series kinematic chains for control, it possesses the advantages of a parallel manipulator: simple structure, high motion accuracy, low energy consumption, and low cost. At the same time, the self-rotating transmission mechanism attached to the kinematic chains adds the function of controlling the object's rotation, thus possessing the advantages of a series manipulator: flexible control and a larger controllable range of motion. Therefore, it allows the advantages of both series and parallel manipulator methods to coexist and their disadvantages to be complementary, greatly expanding the types of manipulator control methods.

[0013] Furthermore, each of the two sets of motion chains is equipped with a self-rotating transmission mechanism that drives the actuator to rotate.

[0014] In this way, the addition of an extra set of self-rotating transmission mechanisms can effectively achieve redundant drive mode, improve the singularity of the mechanism in the workspace, better traverse the singular configuration during movement, reduce singular points of the actuators, and improve the practicality of the application.

[0015] Furthermore, this method is implemented by a parallel manipulator, which includes a base serving as the mounting foundation and an actuator located at the end for grasping objects. Two sets of motion chains, mainly composed of linkages, are mounted side by side on the base and connected to the actuator. The actuator is vertically mounted on an actuator linkage, and both ends of the actuator linkage are rotatably connected to the front ends of the two sets of motion chains. The method also includes at least one set of self-rotating transmission mechanisms attached to any of the motion chains, which drive the actuator linkage to perform synchronous rotational motion.

[0016] In this way, when the robot is in use, the two sets of parallel-installed linkage kinematic chains can drive the actuator link to perform translational motion along the X and Y axes in the plane, realizing the degree of freedom control of the actuator on the actuator link in the X and Y axes of the plane; at the same time, the self-rotation transmission mechanism can further drive the actuator link to perform synchronous rotational motion, thereby realizing the degree of freedom control of the actuator on the actuator link to rotate along the Z axis of the plane through series transmission. Therefore, the present invention combines the advantages of serial and parallel robot arms and achieves complementary disadvantages, while having the characteristics of small error, high precision, and a large range of movement angles of the grasped object.

[0017] Furthermore, each set of motion chains includes a driving rod and a driven rod. One end of the driving rod is vertically fixed to the output shaft of a motion motor fixed to the base. The other end of the driving rod is rotatably connected to one end of the driven rod through a first rotating joint (i.e., a rotating shaft) arranged vertically. The other end of the driven rod is rotatably connected to one end of an actuating link through a second rotating joint arranged vertically. The driven rods of the two sets of motion chains are respectively connected to the two ends of the actuating link. The output shaft of the motion motor, the first rotating joint, and the second rotating joint are all arranged in parallel. One end of the self-rotating transmission mechanism is mounted on the base, and the other end is connected to the driven rod and can drive the driven rod to rotate around the first rotating joint.

[0018] In this way, the two sets of motion chains, the base, and the actuator link together form a closed single motion chain. Two motion motors, through their respective motion chains, can control the actuator link's translational degrees of freedom in the X and Y axes on a plane perpendicular to each joint. Simultaneously, the self-rotation transmission mechanism drives the driven rod to rotate around the first rotary joint, thereby changing the angle between the driven rod and the actuator link. This adds a rotational motion to the actuator link's original translational motion along the X and Y axes, thus achieving three degrees of freedom motion control: X-axis translation, Y-axis translation, and Z-axis rotation. The actuator link component is designed to drive the planar motion of the actuator on it, while simultaneously facilitating the transmission of the self-rotation transmission mechanism to the end of the actuator link, thereby driving the actuator to rotate and achieving rotational degree of freedom control along the Z-axis. Therefore, this structure adds only one link to the conventional five-link two-DOF parallel manipulator, and achieves three-DOF control and adjustment by using only two motion branches and a six-link system. Compared with the conventional three-DOF parallel manipulator, it reduces the number of motion branches and links, greatly simplifies the structure, avoids the constraint on the range of motion caused by too many branches, and increases the working space of the device.

[0019] As an optimized method of the self-rotation transmission mechanism, the self-rotation transmission mechanism includes a self-rotation motor mounted on a base. The self-rotation motor and the corresponding motion motor are coaxially arranged. The self-rotation motor is connected to the end of the driven rod at the corresponding first rotation joint through a belt transmission mechanism and drives the driven rod to rotate around the first rotation joint.

[0020] This method, employing a belt drive mechanism, allows the motor to directly drive the driven rod to rotate around the first rotating joint. It features a simple structure, convenient setup, and ease of implementation. The self-rotating motor is mounted on the base, thus not occupying the mass of the moving parts, resulting in a lightweight overall device that offers flexible and quick control with low energy consumption. However, a drawback is that belt drive mechanisms may experience slippage, leading to a slight reduction in control precision. This method is suitable for applications where high precision is not required but a wide controllable range is desirable.

[0021] Furthermore, the belt drive mechanism is a belt drive mechanism, including a first pulley mounted on the output shaft of the self-rotating motor and a second pulley fixed to the end of the driven rod and coaxially arranged with the first rotating joint.

[0022] This structure is simple, classic, low-cost, and easy to implement. However, in practice, other belt drive mechanisms, such as chain and sprocket drives and synchronous belt drives, can also be used.

[0023] As another optimization of the self-rotation transmission mechanism, the self-rotation transmission mechanism includes a self-rotation motor mounted on a base. The self-rotation motor and the corresponding motion motor are coaxially arranged. A first self-rotation transmission link is vertically fixed on the output shaft of the self-rotation motor. The other end of the first self-rotation transmission link is rotatably connected to the second self-rotation transmission link through a third rotating joint arranged in a vertical direction. The other end of the second self-rotation transmission link is rotatably connected to the middle of the corresponding driven rod through a fourth rotating joint arranged in a vertical direction, forming a parallelogram.

[0024] This parallelogram-shaped four-bar linkage, where a motor drives a driven rod to rotate around a first rotating joint via a first and second self-rotating transmission link, offers advantages such as simple structure, convenient setup, high precision, and reliable transmission. The self-rotating motor is mounted on a base, minimizing its weight on the moving parts and resulting in a lightweight overall device with flexible and quick control and low energy consumption. However, its drawbacks include a relatively complex structure and a greater susceptibility to interference that could reduce the controllable range of motion. It is best suited for applications requiring high precision but a limited controllable range.

[0025] As another optimization of the self-rotating transmission mechanism, the mechanism includes a telescopic cylinder. One end of the telescopic cylinder is rotatably mounted on the output shaft of a corresponding motion motor, and the other end is rotatably connected to the middle of a corresponding driven rod via a rotary joint. The telescopic cylinder can be an electric cylinder, a hydraulic telescopic cylinder, or a pneumatic cylinder. This also allows the driven rod to rotate around the first rotary joint. However, the telescopic cylinder has a relatively large weight, which increases the structural mass of the moving parts of the mechanism and is not conducive to reducing energy consumption.

[0026] As an optimization, the self-rotating transmission mechanism is configured in two sets, each corresponding to one of the two sets of motion branches.

[0027] In this way, by adding a set of self-rotating transmission mechanisms, the added self-rotating motor can be used as a drive device to help the actuator and the grasped object cross singularities during the movement. This allows the entire mechanism to achieve redundant drive. Through redundant drive, the singularity of the mechanism in the workspace can be improved. When encountering singular configurations during movement, the redundant drive can be used to help the mechanism cross those singular configurations.

[0028] Furthermore, the actuator is a cylinder that is vertically mounted and fixed in the middle of the actuator link, and a telescopic rod is mounted on the cylinder along the axial direction, with a vacuum suction cup mounted at the front end of the telescopic rod.

[0029] This design allows for easy gripping of items via suction, and features a simple, compact, and lightweight structure.

[0030] Alternatively, the output shafts of the self-rotating motor and the corresponding motion motor are positioned opposite each other. This facilitates implementation.

[0031] Alternatively, either the self-rotating motor or the corresponding motion motor can be a dual-shaft motor with a hollow output shaft. The output shaft of the other motor can be rotatably fitted inside this hollow output shaft, thus forming a series mounting structure for the two motors. This is convenient for applications where it is necessary to mount the two motors on the same side of the base.

[0032] Furthermore, the links and actuators in each set of motion chains are arranged in a staggered, stepped manner.

[0033] This effectively avoids interference when crossing the middle during movement, allowing for a larger workspace.

[0034] Furthermore, the linkages and motion chains are arranged horizontally, while the motors are arranged vertically. This allows for convenient control of the grasped object's planar movement along the horizontal direction, making it more suitable for practical applications.

[0035] Furthermore, the driven rods on both sides of the actuator are offset and set on the upper and lower sides of the actuator, and the two driving rods are respectively installed below the corresponding driven rods.

[0036] In this way, the two driven rods are staggered and set on the upper and lower sides of the actuator link. The driven rods are located at the closest and equidistant positions from the upper and lower ends of the actuator link in the vertical direction. Therefore, the adverse effects of the torque generated by gravity when the driven rods drive the actuator link to rotate can be minimized and the influence on the left and right sides can be balanced. At the same time, the two driving rods are installed below the corresponding driven rods. This can minimize interference and make the motors of the two sets of motion chains as close as possible in the height direction. This makes the overall structure more compact, the force distribution more scientific, and the adverse effects of the gravitational torque less.

[0037] Furthermore, the motion motors of the two sets of motion chains are installed on corresponding, spaced-apart split bases. When the driving rods in the two sets of motion chains rotate to a position directly opposite each other, the distance between the two first rotating joints is less than the length of the driven rod, but the distance from any first rotating joint to the other split base is greater than the length of the driven rod, and the length of the driven rod is greater than the length of the actuating link.

[0038] In this way, when the two sets of kinematic chains drive the actuator link to the position between the two bases, the interference between the driven link below the actuator link and the actuator link can stop the lower actuator link. Then, another kinematic chain drives the actuator link to change its angle and orientation, altering its trajectory. This allows the actuator link to cross the line connecting the two separate bases, achieving a traverse of the left-right region of that line. Furthermore, since the interference position between the actuator link and the lower driven link is fixed, the magnitude of the angle change driven by the other kinematic chain during this process is controllable; that is, the entire trajectory of the actuator link remains within a controllable range. This cleverly utilizes interference to achieve a large controllable range of motion within a relatively small base installation space.

[0039] Therefore, this invention has the following beneficial effects: 1. Compared with planar three-degree-of-freedom parallel robots, this invention adopts a closed single kinematic chain, which can realize three degrees of freedom in the plane. The overall mechanical structure is relatively simple, reducing the total number of branches and the interference between branches, thereby increasing the working space of the mechanism. When a belt drive mechanism is used, the motion performance and flexibility are improved. 2. Compared with planar three-degree-of-freedom serial robots, this invention has a closed kinematic chain, which has a stronger load-bearing capacity, reduces the motion error of each component, improves the motion accuracy of the entire robotic arm, and the drive motors are all fixed on the base frame, reducing the robot's own motion inertia, resulting in better dynamic performance and faster running speed. 3. This invention is a six-bar linkage with a parallel layout. Although it is not strictly symmetrical, the mechanism still has good isotropy. 4. This invention uses a coaxial drive method, that is, placing two servo motors symmetrically or coaxially in series, which can reduce the installation space occupied. At the same time, the use of belt drive reduces the weight of the linkage joints, reduces the motion inertia of the mechanism, improves the motion performance of the system, and also reduces interference and increases the overall working space of the mechanism. 5. Compared with a planar two-DOF five-bar parallel robot, this invention has three degrees of freedom in the plane, enabling it to perform more functions. 6. This invention can implement a redundant drive mode. Through redundant drive, the singularity of the mechanism in the workspace can be improved. When encountering singular configurations during movement, redundant drive can be used to allow the mechanism to overcome those configurations.

[0040] In summary, the present invention has the advantage of being able to improve the range of motion of an object in a simpler way. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the structure of the first embodiment of the present invention.

[0042] Figure 2 This is a simplified structural diagram of the first embodiment.

[0043] Figure 3 This is a schematic diagram of the actuator in the middle cross position in the first embodiment.

[0044] Figure 4 This is a simplified structural diagram of the second embodiment of the present invention.

[0045] Figure 5 This is a schematic diagram of the structure of the third embodiment of the present invention.

[0046] Figure 6 This is a simplified structural diagram of the third embodiment.

[0047] Figure 7 This is a simplified structural diagram of the fourth embodiment of the present invention. Detailed Implementation

[0048] The present invention will now be described in further detail with reference to specific embodiments.

[0049] In specific implementation: A method for controlling the planar motion of an object using a robotic arm. In this method, an actuator grips and fixes the object, and then the actuator is controlled to achieve planar motion by two sets of motion chains mainly composed of connecting rods installed on the base. Its feature is that, through the self-rotating transmission mechanism attached to the motion chains, the actuator is driven to rotate synchronously while the two sets of motion chains control the planar motion of the actuator.

[0050] In this way, by controlling the translational motion (displacement along the X and Y axes) of the actuator through two sets of motion chains in a parallel manipulator, and simultaneously driving the actuator to rotate synchronously through a self-rotating transmission mechanism attached to the motion chains, the object can be further oriented during the grasping and translation process, adding a degree of freedom for rotation along the Z axis. This significantly improves the directional control range of the object's planar movement. Furthermore, this method combines the advantages of both series and parallel manipulators. Since this method primarily relies on two sets of series motion chains for control, it possesses the advantages of a parallel manipulator: simple structure, high motion accuracy, low energy consumption, and low cost. At the same time, the self-rotating transmission mechanism attached to the motion chains adds the ability to control the object's rotation, thus also possessing the advantages of a series manipulator: flexible control and a wider controllable range of motion. Therefore, it allows the advantages of both series and parallel manipulator methods to coexist and their disadvantages to be complementary, greatly expanding the types of manipulator control methods.

[0051] Each of the two sets of motion chains is equipped with a self-rotating transmission mechanism that drives the actuator to rotate.

[0052] In this way, the addition of an extra set of self-rotating transmission mechanisms can effectively achieve redundant drive mode, improve the singularity of the mechanism in the workspace, better traverse the singular configuration during movement, reduce singular points of the actuators, and improve the practicality of the application.

[0053] Specifically, this method can be implemented using parallel robotic arms in the following specific embodiments.

[0054] First embodiment, see Figure 1-3 A parallel robotic arm includes a base 10 serving as a mounting foundation. Figure 1The base is not shown (it can be a single base or a split base) and an actuator 1 is set at the end for grasping objects. Two sets of motion chains, mainly composed of connecting rods, are installed side by side on the base and connected to the actuator 1. The actuator 1 is vertically mounted on an actuator link 2. The two ends of the actuator link 2 are rotatably connected to the front ends of the two sets of motion chains respectively. It also includes at least one set of self-rotation transmission mechanism attached to any of the motion chains. The self-rotation transmission mechanism is used to drive the actuator link to perform synchronous rotational motion.

[0055] In this way, when the robot is in use, the two sets of parallel-installed linkage kinematic chains can drive the actuator link to perform translational motion along the X and Y axes in the plane, realizing the degree of freedom control of the actuator on the actuator link in the X and Y axes of the plane; at the same time, the self-rotation transmission mechanism can further drive the actuator link to perform synchronous rotational motion, thereby realizing the degree of freedom control of the actuator on the actuator link to rotate along the Z axis of the plane through series transmission. Therefore, the present invention combines the advantages of serial and parallel robot arms and achieves complementary disadvantages, while having the characteristics of small error, high precision, and a large range of movement angles of the grasped object.

[0056] Each set of motion chains includes a driving rod 3 and a driven rod 4. One end of the driving rod 3 is vertically fixed to the output shaft of a motion motor 5 fixed to the base. The other end of the driving rod 3 is rotatably connected to one end of the driven rod 4 through a first rotating joint 6 (i.e., a rotating shaft) arranged vertically. The other end of the driven rod 4 is rotatably connected to one end of the actuating link 2 through a second rotating joint 7 arranged vertically. The driven rods of the two sets of motion chains are respectively connected to the two ends of the actuating link 2. The output shaft of the motion motor 5, the first rotating joint 6, and the second rotating joint 7 are all arranged in parallel. One end of the self-rotating transmission mechanism is mounted on the base, and the other end is connected to the driven rod and can drive the driven rod to rotate around the first rotating joint.

[0057] In this way, the two sets of motion chains, the base, and the actuator link together form a closed single motion chain. This chain allows for the control of the actuator link's translational degrees of freedom along the X and Y axes in a plane perpendicular to each joint, achieved through two motion motors and their respective motion chains. Simultaneously, the self-rotation transmission mechanism drives the driven rod to rotate around the first rotary joint, thereby changing the angle between the driven rod and the actuator link. This adds a rotational motion to the actuator link's original translational motion along the X and Y axes, thus achieving three degrees of freedom motion control: X-axis translation, Y-axis translation, and Z-axis rotation. The actuator link component is designed to facilitate the translational motion of the actuator on it, while simultaneously allowing the transmission mechanism to reach the end of the actuator link, thereby driving the actuator to rotate and achieving rotational degree of freedom control along the Z-axis. Therefore, this structure adds only one link to the conventional five-link two-DOF parallel manipulator, and achieves three-DOF control and adjustment by using only two motion branches and a six-link system. Compared with the conventional three-DOF parallel manipulator, it reduces the number of motion branches and links, greatly simplifies the structure, avoids the constraint on the range of motion caused by too many branches, and increases the working space of the device.

[0058] The self-rotation transmission mechanism includes a self-rotation motor 8 mounted on a base. The self-rotation motor 8 and the corresponding motion motor are coaxially arranged. The self-rotation motor 8 is connected to the driven rod end at the corresponding first rotation joint 6 through a belt transmission mechanism 9 and drives the driven rod 4 to rotate around the first rotation joint 6.

[0059] This method, employing a belt drive mechanism, allows the motor to directly drive the driven rod to rotate around the first rotating joint. It features a simple structure, convenient setup, and ease of implementation. The self-rotating motor is mounted on the base, thus not occupying the mass of the moving parts, resulting in a lightweight overall device that offers flexible and quick control with low energy consumption. However, a drawback is that belt drive mechanisms may experience slippage, leading to a slight reduction in control precision. This method is suitable for applications where high precision is not required but a wide controllable range is desirable.

[0060] The belt drive mechanism 9 is a belt drive mechanism, which includes a first pulley mounted on the output shaft of the self-rotating motor and a second pulley fixed to the end of the driven rod and coaxially arranged with the first rotating joint.

[0061] This structure is simple, classic, low-cost, and easy to implement. However, in practice, other belt drive mechanisms, such as chain and sprocket drives and synchronous belt drives, can also be used.

[0062] The actuator 1 is a cylinder that is vertically mounted and fixed in the middle of the actuator link. A telescopic rod is mounted on the cylinder along the axial direction and a vacuum suction cup is mounted at the front end of the telescopic rod.

[0063] This design allows for easy gripping of items via suction, and features a simple, compact, and lightweight structure.

[0064] In this embodiment, the output shafts of the self-rotating motor 8 and the corresponding motion motor 5 are arranged opposite each other. This facilitates implementation.

[0065] In each set of motion chains, the links and actuators are arranged in a staggered, stepped manner.

[0066] This effectively avoids interference when crossing the middle during movement. See [link / reference] Figure 3 To obtain the largest possible workspace.

[0067] The linkages and motion chains are arranged horizontally, while the motors are arranged vertically. This design allows for easy control of the grasped object's horizontal planar movement, making it more suitable for practical applications.

[0068] Among them, the driven rods on both sides of the actuator are staggered and set on the upper and lower sides of the actuator, and the two driving rods are respectively installed below the corresponding driven rods.

[0069] In this way, the two driven rods are staggered and set on the upper and lower sides of the actuator link. The driven rods are located at the closest and equidistant positions from the upper and lower ends of the actuator link in the vertical direction. Therefore, the adverse effects of the torque generated by gravity when the driven rods drive the actuator link to rotate can be minimized and the influence on the left and right sides can be balanced. At the same time, the two driving rods are installed below the corresponding driven rods. This can minimize interference and make the motors of the two sets of motion chains as close as possible in the height direction. This makes the overall structure more compact, the force distribution more scientific, and the adverse effects of the gravitational torque less.

[0070] In this system, the motion motors of the two sets of motion chains are mounted on corresponding, spaced-apart separate bases. When the driving rods in the two sets of motion chains rotate to a position directly opposite each other, the distance between the two first rotating joints is less than the length of the driven rod, but the distance from any first rotating joint to the other separate base is greater than the length of the driven rod, and the length of the driven rod is greater than the length of the actuating link. See also... Figure 3 .

[0071] In this way, when the two sets of kinematic chains drive the actuator link to the position between the two bases, the interference between the driven link below the actuator link and the actuator link can stop the lower actuator link. Then, another kinematic chain drives the actuator link to change its angle and orientation, altering its trajectory. This allows the actuator link to cross the line connecting the two separate bases, achieving a traverse of the left-right region of that line. Furthermore, since the interference position between the actuator link and the lower driven link is fixed, the magnitude of the angle change driven by the other kinematic chain during this process is controllable; that is, the entire trajectory of the actuator link remains within a controllable range. This cleverly utilizes interference to achieve a large controllable range of motion within a relatively small base installation space.

[0072] The second embodiment differs from the first embodiment only in the structure of the self-rotation transmission mechanism; the rest of the structure is exactly the same.

[0073] See Figure 4 In this embodiment, the self-rotation transmission mechanism includes a self-rotation motor mounted on a base. The self-rotation motor and the corresponding motion motor are coaxially arranged. A first self-rotation transmission link 11 is vertically fixed on the output shaft of the self-rotation motor. The other end of the first self-rotation transmission link 11 is rotatably connected to a second self-rotation transmission link 13 through a third rotating joint 12 arranged in a vertical direction. The other end of the second self-rotation transmission link 13 is rotatably connected to the middle of the corresponding driven rod 4 through a fourth rotating joint 14 arranged in a vertical direction, forming a parallelogram.

[0074] This parallelogram-shaped four-bar linkage, where a motor drives a driven rod to rotate around a first rotating joint via a first and second self-rotating transmission link, offers advantages such as simple structure, convenient setup, high precision, and reliable transmission. The self-rotating motor is mounted on a base, minimizing its weight on the moving parts and resulting in a lightweight overall device with flexible and quick control and low energy consumption. However, its drawbacks include a relatively complex structure and a greater susceptibility to interference that could reduce the controllable range of motion. It is best suited for applications requiring high precision but a limited controllable range.

[0075] Third embodiment, see Figure 5 and Figure 6Compared to the second embodiment, the only difference between the parallel manipulator in this embodiment and the second embodiment is that the self-rotation transmission mechanism is configured in two sets, each corresponding to one of the two sets of motion chains. By adding a set of self-rotation transmission mechanisms, the added self-rotating motor can be used as a drive device to help the actuator and the grasped object cross singularities during movement. This allows the entire mechanism to achieve redundant drive. Through redundant drive, the singularity of the mechanism within the workspace can be improved. When encountering singular configurations during movement, redundant drive can be used to help the mechanism overcome those configurations.

[0076] In this embodiment, either the self-rotating motor 8 or the corresponding motion motor 5 is a dual-shaft motor with a hollow output shaft. The output shaft of the other motor is rotatably fitted inside this output shaft, thus forming a series mounting structure for the two motors. This is convenient for implementation in situations where it is necessary to mount the two motors on the same side of the base.

[0077] The remaining parts of this embodiment are completely identical to those of the second embodiment, and will not be described in detail here.

[0078] Fourth embodiment, see Figure 7 The only difference between the parallel manipulator in this embodiment and the third embodiment is that the self-rotation transmission mechanism adopts the same belt transmission mechanism as the first embodiment; the rest of the structure is exactly the same as the third embodiment.

[0079] Alternatively, the self-rotating transmission mechanism can also employ other structural methods during implementation. For example, the self-rotating transmission mechanism includes a telescopic cylinder, one end of which is rotatably mounted on the output shaft of a corresponding motion motor, and the other end is rotatably connected to the middle of a corresponding driven rod via a rotating joint. The telescopic cylinder can be an electric cylinder, a hydraulic telescopic cylinder, or a pneumatic cylinder, etc. This also allows the driven rod to rotate around the first rotating joint. However, the telescopic cylinder has a relatively large self-weight, which increases the structural mass of the moving parts of the mechanism, making it less conducive to reducing energy consumption.

[0080] Therefore, this invention has the following beneficial effects: 1. Compared with planar three-degree-of-freedom parallel robots, this invention adopts a closed single kinematic chain, which can realize three degrees of freedom in the plane. The overall mechanical structure is relatively simple, reducing the total number of branches and the interference between branches, thereby increasing the working space of the mechanism. When a belt drive mechanism is used, the motion performance and flexibility are improved. 2. Compared with planar three-degree-of-freedom serial robots, this invention has a closed kinematic chain, which has a stronger load-bearing capacity, reduces the motion error of each component, improves the motion accuracy of the entire robotic arm, and the drive motors are all fixed on the base frame, reducing the robot's own motion inertia, resulting in better dynamic performance and faster running speed. 3. This invention is a six-bar linkage with a parallel layout. Although it is not strictly symmetrical, the mechanism still has good isotropy. 4. This invention uses a coaxial drive method, that is, placing two servo motors symmetrically or coaxially in series, which can reduce the installation space occupied. At the same time, the use of belt drive reduces the weight of the linkage joints, reduces the motion inertia of the mechanism, improves the motion performance of the system, and also reduces interference and increases the overall working space of the mechanism. 5. Compared with a planar two-DOF five-bar parallel robot, this invention has three degrees of freedom in the plane, enabling it to perform more functions. 6. This invention can implement a redundant drive mode. Through redundant drive, the singularity of the mechanism in the workspace can be improved. When encountering singular configurations during movement, redundant drive can be used to allow the mechanism to overcome those configurations.

Claims

1. A parallel robotic arm, comprising a base serving as a mounting foundation and an actuator disposed at the end for grasping objects, wherein two sets of kinematic chains, mainly composed of linkages, are mounted side-by-side on the base and connected to the actuator, characterized in that, The actuator is vertically mounted on an actuator link, and the two ends of the actuator link are rotatably connected to the front ends of two sets of motion chains respectively. It also includes at least one set of self-rotation transmission mechanism attached to any of the motion chains. The self-rotation transmission mechanism is used to drive the actuator link to perform synchronous rotational motion. Each set of motion chains includes a driving rod and a driven rod. One end of the driving rod is vertically fixed to the output shaft of a motion motor fixed to the base. The other end of the driving rod is rotatably connected to one end of the driven rod via a first rotating joint arranged vertically. The other end of the driven rod is rotatably connected to one end of an actuating link via a second rotating joint arranged vertically. The driven rods of the two sets of motion chains are respectively connected to the two ends of the actuating link. The output shaft of the motion motor, the first rotating joint, and the second rotating joint are all arranged in parallel. One end of the self-rotating transmission mechanism is mounted on the base, and the other end is connected to the driven rod and can drive the driven rod to rotate around the first rotating joint. The actuator is a cylinder that is vertically mounted and fixed in the middle of the actuator link. A telescopic rod is mounted on the cylinder along the axial direction and a vacuum suction cup is mounted at the front end of the telescopic rod. Each link and motion chain is set horizontally, and each motor is set vertically. The driven rods on both sides of the actuator are staggered and set on the upper and lower sides of the actuator. The driven rods are located at the closest positions to the upper and lower ends of the actuator in the vertical direction and are equidistant. The two driving rods are installed below the corresponding driven rods. The motors of the two sets of motion chains are mounted on corresponding, spaced-apart split bases. When the driving rods in the two sets of motion chains rotate to a position facing each other, the distance between the two first rotating joints is less than the length of the driven rod, but the distance from any first rotating joint to the other split base is greater than the length of the driven rod, and the length of the driven rod is greater than the length of the actuating link. This allows the two sets of motion chains to drive the actuating link to move to the position between the two bases. By relying on the interference between the driven rod located below the actuating link and the actuating link, the actuating link located below is stopped. Then, by relying on the other motion chain, the actuating link changes its angle and orientation, changing its trajectory. This allows the actuating link to cross the line between the two split bases, thus achieving a traverse of the left and right regions of that line.

2. The parallel robotic arm as described in claim 1, characterized in that, The self-rotation transmission mechanism includes a self-rotating motor mounted on a base. The self-rotating motor and the corresponding motion motor are coaxially arranged. The self-rotating motor is connected to the end of the driven rod at the corresponding first rotation joint through a belt transmission mechanism and drives the driven rod to rotate around the first rotation joint.

3. The parallel robotic arm as described in claim 2, characterized in that, The belt drive mechanism is a belt drive mechanism, including a first pulley mounted on the output shaft of the self-rotating motor and a second pulley fixed to the end of the driven rod and coaxially arranged with the first rotating joint.

4. The parallel robotic arm as described in claim 1, characterized in that, The self-rotation transmission mechanism includes a self-rotating motor mounted on a base. The self-rotating motor and a corresponding motion motor are coaxially arranged. A first self-rotation transmission link is vertically fixed on the output shaft of the self-rotating motor. The other end of the first self-rotation transmission link is rotatably connected to a second self-rotation transmission link through a third rotating joint arranged in a vertical direction. The other end of the second self-rotation transmission link is rotatably connected to the middle of the corresponding driven rod through a fourth rotating joint arranged in a vertical direction, forming a parallelogram.

5. The parallel robotic arm as described in claim 1, characterized in that, The self-rotating transmission mechanism includes a telescopic cylinder, one end of which is rotatably mounted on the output shaft of the corresponding motion motor, and the other end is rotatably connected to the middle of the corresponding driven rod via a rotating joint.

6. The parallel robotic arm as described in claim 1, characterized in that, The self-rotation transmission mechanism consists of two sets, each corresponding to one of the two sets of motion branches.

7. The parallel robotic arm as described in claim 1, characterized in that, The output shafts of the self-rotating motor and the corresponding motion motor are arranged opposite each other; or either the self-rotating motor or the corresponding motion motor is a dual-shaft motor with its output shaft hollow, and the output shaft of the other motor is rotatably fitted inside the output shaft, so that the two motors form a series installation structure.

8. The parallel robotic arm as described in claim 3, characterized in that, The links and actuators in each set of motion chains are arranged in a staggered, stepped manner.

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