A metamorphic robot with remote center motion and schonflies motion modes

Abstract

This invention discloses a morphological robot with remote center motion and motion modes, comprising four robotic arms connected in pairs by revolute joints and a motion module. The first robotic arm is connected to the second and third robotic arms at both ends via right-angle connectors. The motion module is installed inside the fourth robotic arm and includes a splined lead screw shaft, a splined nut, and a lead screw nut connected to the lead screw shaft via a spline joint. An actuator is connected to the end of the splined lead screw shaft via a flange; by driving the splined lead screw shaft individually or simultaneously, the splined lead screw shaft can output a two-degree-of-freedom motion of one rotation and one translation. The fourth robotic arm is connected to the other ends of the second and third robotic arms at both ends via revolute joints, giving the fourth robotic arm a two-degree-of-freedom rotational and translational motion relative to the first robotic arm. Ultimately, the entire morphological robot can achieve two different motion modes: a four-degree-of-freedom motion of three translations and one rotation, and a four-degree-of-freedom remote center motion of three rotations and one translation.

Description

Technical Field

[0001] This invention belongs to the field of robotics technology and relates to a device with remote central motion and A morphological robot with a specific motion pattern. Background Technology

[0002] Because rigid bodies have only six degrees of freedom in space, six-degree-of-freedom (DOF) general-purpose robots are widely used in robotics, especially in industrial robotics, such as the PUMA and Stanford six-DOF robotic arms. However, for most tasks, the robot's end effector often does not need six degrees of freedom. Although a six-DOF general-purpose robot can achieve any motion with fewer than six degrees of freedom in space, the number of its degrees of freedom is greater than the actual required motion degrees of freedom, making the robot structure more complex. Furthermore, when performing tasks with fewer than six degrees of freedom, the motion between different actuators of a six-axis robot is coupled, increasing the difficulty of robot motion control. Therefore, low-DOF robots for tasks with fewer than six degrees of freedom have also been widely researched and applied. The most typical examples are the three-transfer-one-rotation four-DOF SCARA robot, widely used in industrial production for tasks such as planar handling and assembly, and the three-rotation-one-transfer four-DOF Da Vinci robot for fixed-point operation in minimally invasive surgery. Because the number of motion degrees of freedom of these robots is the same as the number of degrees of freedom required for the task, these robots have a compact structure, simple control, and fast dynamic response.

[0003] However, unlike six-axis general-purpose robots that can be applied to any spatial operation task, space robots with fewer than six degrees of freedom (DOF) cannot achieve the same variety of tasks as general-purpose six-axis robots because their motion modes cannot cover all the motions of a rigid body in space. This results in lower versatility compared to six-DOF robots. Variable-dimensional mechanisms and robots, on the other hand, can achieve different operating modes through a single mechanism and drive system, enabling multi-purpose functionality. Therefore, compared to six-DOF general-purpose robots, they have advantages such as simpler structure, no redundant drives, and simpler motion control. Furthermore, compared to traditional low-DOF robots with only a single operating mode, their variable operating modes offer greater versatility and adaptability for different tasks. Therefore, variable-dimensional robots have enormous application potential in multi-mode operation in unstructured environments, variable task operations in industrial production, and multi-mode operation in minimally invasive surgery. Summary of the Invention

[0004] To address the above problems, this invention proposes a method with remote center motion and The metamorphic robot with a specific motion pattern can achieve four degrees of freedom (three translations and one rotation) through a single mechanism and drive unit. Two different typical robot operations: the motion mode and the four-degree-of-freedom remote center motion mode of three rotations and one transfer.

[0005] This invention provides a remote center motion and The morphological robot with motion modes only requires four drive motors combined with joint limit design to achieve switching between two different four-degree-of-freedom operation tasks. No redundant drive is required when switching operation modes, and motion control is simple and reliable.

[0006] This invention has remote center motion and The morphological robot with a motion pattern includes a first robotic arm, a second robotic arm, a third robotic arm, a fourth robotic arm, and a motion module.

[0007] A first drive motor is installed at the front end of the first robotic arm. The inner side of a first right-angle connector faces the first robotic arm, and one side is fixedly connected to the output shaft of the first drive motor, forming a revolute joint A. The outer side of a second right-angle connector faces the first robotic arm, and one side is connected to the rear end of the first robotic arm, forming a revolute joint B. The other side of the first right-angle connector is connected to one end of the second robotic arm, forming a revolute joint C. A second drive motor is installed on the other side of the second right-angle connector, and the output shaft of the second drive motor is fixedly connected to one end of the third robotic arm, forming a revolute joint D. The other ends of the second and third robotic arms are respectively connected to the front and rear ends of the fourth robotic arm, forming revolute joints E and F. This gives the fourth robotic arm two degrees of freedom relative to the first robotic arm—rotation and translation. A mechanical limit is designed at the aforementioned kinematic joint E.

[0008] The fourth robotic arm is internally equipped with a motion module, which includes a splined screw shaft module and a drive mechanism. The splined screw shaft comprises a splined screw shaft and a splined nut and a screw nut connected to it via a spline pair. The splined nut and screw nut are driven by the drive mechanism to rotate individually or together. The front end of the splined screw shaft protrudes through the front face of the fourth robotic arm, and an actuator connecting flange is designed at its end. When the splined nut is driven to rotate alone, the splined screw shaft outputs helical motion; when the screw nut is driven to rotate alone, the splined screw shaft outputs pure translational motion along the axial direction; when the splined nut and screw nut are driven to rotate simultaneously, the splined screw shaft outputs pure rotational motion, resulting in a two-degree-of-freedom motion (one rotation and one translation) on the splined screw shaft. Combined with the aforementioned two-degree-of-freedom rotational and translational motion of the fourth robotic arm relative to the first robotic arm, a four-degree-of-freedom motion is obtained between the actuator connecting flange at the end of the splined screw shaft and the first robotic arm. This four-degree-of-freedom motion has two different forms, generating the robot's... The motion and remote center motion operation modes are as follows:

[0009] When the robot is in In motion operation mode, the axes of revolute joint A and revolute joint B coincide, and the motion axes of revolute joints C, D, E, and revolute joint F are all parallel to each other. At this time, the mechanical limit at revolute joint E does not make contact. The spline screw shaft and its end actuator connecting flange have rotational and translational degrees of freedom relative to the fourth robotic arm, and the rotational axis of the spline screw shaft is always parallel to the common axis of revolute joints A and B. Therefore, the final motion output by the actuator connecting flange at the end of the spline screw shaft in the fourth robotic arm relative to the first robotic arm is a four-degree-of-freedom motion with 3 translations and 1 rotation. Furthermore, during the motion, the rotational direction is always parallel to the common axis of revolute joints B and C, thus achieving… Motion mode. In this motion mode, the robot's operating space is a hollow cylinder with the common axis of revolute joints B and C as its axis.

[0010] When the robot moves from the aforementioned 3-step to 1-step turn When the robot moves to the bifurcation point, the motion axes of revolute joints D and E coincide, and the robot exhibits two different motion mode tendencies. When the robot reaches the bifurcation configuration, the mechanical limiting contact at revolute joint E causes the second drive motor to drive revolute joint D to rotate clockwise, while the counterclockwise rotation of revolute joint E is restricted, preventing the robot from continuing to move. In motion mode, the axes of motion of rotary joints D and E remain aligned, and rotary joint E will rotate clockwise along with rotary joint D, thus entering the remote center motion mode of 3 rotations and 1 shift.

[0011] When revolute joint E rotates clockwise following revolute joint D, the mechanical limit at kinematic joint E is released. At this point, the fourth robotic arm has two rotational degrees of freedom relative to the first robotic arm. The first rotational axis is the common axis of revolute joints A and B, and the second rotational axis is the coincident axis of revolute joints D and E. The two rotational axes are perpendicular and orthogonal at point O. Simultaneously, the rotational axis of the spline screw shaft in the fourth robotic arm will also intersect the above two axes at point O. Therefore, the motion mode of the actuator connecting flange at the end of the robot's end effector and the spline screw shaft is a combination of three-dimensional rotational motion around the common intersection point O of the three rotational axes and translational motion along the direction of the third rotational axis, resulting in a four-degree-of-freedom motion (3 rotations and 1 translation). In this motion mode, the robot's workspace is a hollow sphere, with the center of the sphere being the common intersection point O of the three rotational axes.

[0012] The advantages of this invention are:

[0013] 1. This invention has remote center motion and The metamorphic robot with a specific motion pattern can achieve four degrees of freedom (three translations and one rotation) through a single mechanism and drive unit. Two different typical robot operations: the motion mode and the four-degree-of-freedom remote center motion mode of three rotations and one transfer.

[0014] 2. This invention has remote center motion and The morphological robot with motion modes only requires four drive motors combined with joint limit design to achieve switching between two different four-degree-of-freedom operation tasks. No redundant drive is required when switching modes, and motion control is simple and reliable.

[0015] 3. This invention has remote center motion and The rotation and translation of the end effector of the metamorphic robot in motion mode are achieved through a spline screw. The whole machine has a compact structure, high motion accuracy and reliability, and good dynamic response capability. Attached Figure Description

[0016] Figure 1 The present invention has remote center motion and A schematic diagram of the overall structure of the morphological robot with a specific motion pattern.

[0017] Figure 2 The present invention has remote center motion and A schematic diagram of the first robotic arm of a morphological robot with a motion pattern.

[0018] Figure 3 The present invention has remote center motion and A schematic diagram of the base structure of the first robotic arm of the morphological robot with a motion pattern.

[0019] Figure 4 The present invention has remote center motion and A schematic diagram of the first right-angle linkage structure of a morphological robot with a motion pattern.

[0020] Figure 5 The present invention has remote center motion and A schematic diagram of the second right-angle linkage structure of a morphological robot with a motion pattern.

[0021] Figure 6 The present invention has remote center motion and A schematic diagram of the second robotic arm of a morphological robot with a motion pattern.

[0022] Figure 7 The present invention has remote center motion and A schematic diagram of the third robotic arm of a morphological robot with a motion pattern.

[0023] Figure 8 The present invention has remote center motion and A schematic diagram of the fourth robotic arm of the morphological robot with a motion pattern.

[0024] Figure 9 The present invention has remote center motion and A schematic diagram of the motion module structure of the morphological robot with 1 translation and 1 rotation.

[0025] Figure 10 The present invention has remote center motion and A schematic diagram of the spline screw module structure in a variable-cell robot with motion modes.

[0026] Figure 11 The present invention has remote center motion and A schematic diagram of the spline screw module installation method in a variable-cell robot with motion mode.

[0027] Figure 12 The present invention has remote center motion and The morphological robot with a specific motion pattern is in Distribution diagram of kinematic pair axes during motion operation mode.

[0028] Figure 13 The present invention has remote center motion and The morphological robot with a specific motion pattern is in Workspace diagram during motion operation mode.

[0029] Figure 14 The present invention has remote center motion and State diagram of a morphological robot in different motion modes when switching configurations.

[0030] Figure 15 The present invention has remote center motion and Distribution diagram of kinematic axis of the morphobot in remote center motion operation mode.

[0031] Figure 16 The present invention has remote center motion and Workspace diagram of a morphological robot in remote central motion operation mode.

[0032] In the picture:

[0033] 1-First robotic arm 2-Second robotic arm 3-Third robotic arm

[0034] 4-Fourth robotic arm; 5-First drive motor; 6-Second motor

[0035] 7-Base box; 8-First right-angle connector; 9-Second right-angle connector

[0036] 201-Second robotic arm end hole A 202-Second robotic arm end hole B 203-End protrusion

[0037] 301 - Third robotic arm end hole A; 302 - Third robotic arm end hole B; 303 - Radial threaded hole

[0038] 401 - Robotic arm housing; 402 - Motion module; 401a - Upper part of housing

[0039] 401b - Lower half of the enclosure; 401c - Left rear side round hole; 401d - Cylindrical connector

[0040] 401e - Right front round hole; 401f - Arc-shaped recess; 401g - Upper connecting plate A

[0041] 401h - Upper connecting plate B; 401i - Lower connecting plate A; 401j - Lower connecting plate B

[0042] 401k - Positioning groove; 401m - Connecting plate shaft hole A; 401n - Connecting plate shaft hole B

[0043] 401p - Upper connecting shoulder; 401q - Lower connecting shoulder; 402a - Spline screw module

[0044] 402b - Spline nut drive motor; 402c - Lead screw nut drive motor; 402d - Drive pulley A

[0045] 402e - Driven pulley A; 402f - Driving pulley B; 402g - Driven pulley B

[0046] 402h - Synchronous belt; 402i - Actuator connecting flange; 402a1 - Splined screw shaft

[0047] 402a2 - Spline nut; 402a3 - Lead screw nut; 402a4 - Connecting hole A

[0048] 402a5 - Connecting threaded hole A; 402a6 - Connecting hole B; 402a7 - Connecting threaded hole B

[0049] 701 - Upper half of the base box; 702 - Lower half of the base box; 703 - Large round hole in the base box

[0050] 704 - Small round hole in base box; 705 - Shaft hole in base box; 801 - Round hole in first boss.

[0051] 802 - First boss threaded hole; 803 - First through hole; 804 - First circular boss

[0052] 901 - Second boss circular hole; 902 - Outer circular hole; 903 - Second through hole Detailed Implementation

[0053] The invention will now be further described with reference to the accompanying drawings.

[0054] like Figure 1 As shown, the present invention has remote center motion and The kinetic modal robot is mainly composed of four robotic arms, including a first robotic arm 1, a second robotic arm 2, a third robotic arm 3, and a fourth robotic arm 4. The different robotic arms are hinged together by revolute joints and driven by joint motors.

[0055] The structure of the first robotic arm 1 is as follows Figure 2 As shown, the first robotic arm 1 is composed of a first drive motor 5, a second drive motor 6, a base box 7, a first right-angle connector 8, and a second right-angle connector 9.

[0056] The base box 7 is composed of an upper part 701 and a lower part 702. Both the upper part 701 and the lower part 702 have U-shaped cross-sections, and shoulders are designed along the front-to-back direction on both sides. Through holes are evenly distributed along the front-to-back direction on the shoulders. Bolts are tightened into the corresponding through holes on the shoulders of the upper and lower parts 701 and 702, thus fixing the upper and lower parts of the base box together and forming a base box 7 with an overall rectangular cross-section. Figure 3 As shown. A large circular hole 703 is located at the center of the front face of the base box 7. Four small circular holes 704 are located around the large circular hole 703, at the four corners of the front side of the base box 7, for mounting the first drive motor 5. A shaft hole 705 is located on the rear face of the base box 7, coaxial with the large circular hole 703, for connecting the first right-angle connector 8. A connecting through hole is also provided on the side wall of the base box 7 for mounting and positioning the morphological robot of this invention using screws.

[0057] The first drive motor 5 is located inside the base box 7. Its output shaft passes through the large round hole 703 of the base box and exits the front face of the base box 7. At the same time, the first drive motor 5 is connected and fixed to the front face of the base box 7 by screws at the four small round holes 704 of the base box.

[0058] The first right-angle connector 8 is a right-angle plate structure with two mutually perpendicular sides and a bottom surface, such as... Figure 4 As shown. The first right-angle connector 8 has a first through hole 803 on its side surface and a first circular boss 804 on its inner bottom surface. A first boss circular hole 801 is axially located at the center of the first circular boss 804. The axis of the first boss circular hole 801 is perpendicular to the axis of the first through hole 803 on the side surface, forming a 90° angle. Simultaneously, a first boss threaded hole 802 is radially formed on the first circular boss 804, and the axis of the first boss threaded hole 802 is perpendicular to the axis of the first boss circular hole 801, forming a 90° angle.

[0059] The structure of the second right-angle connector 9 is similar to that of the first right-angle connector 8, also having two mutually perpendicular side surfaces and a bottom surface, as shown below. Figure 5 As shown. The inner side of the second right-angle connector 9 is designed with a second circular boss 904, and a second circular hole 901 is radially formed at the center of the second circular boss 904; simultaneously, four peripheral circular holes 902 are evenly distributed around the periphery of the second circular boss 904. A second through hole 903 is formed on the bottom surface of the second right-angle connector 9, and its axis is perpendicular to the axis of the second central circular hole 901 at a 90° angle.

[0060] The inner side of the bottom surface of the first right-angle connector 8 faces the front end of the first robotic arm 1. The first boss circular hole 801 on the bottom surface is engaged with the output shaft of the first drive motor 5 and is tightened and fixed by the set screw installed in the threaded hole 802 of the first boss, forming a rotating pair A.

[0061] The outer side of the bottom surface of the aforementioned second right-angle connector 9 faces the rear end face of the first robotic arm 1. The second circular hole 903 on the bottom surface is connected to the base box shaft hole 705 at the center of the rear end of the base box 7 by a pin, forming a rotating pair B. A second drive motor 6 is installed on the outer side wall of the second right-angle connector 9. The output shaft of the second drive motor 6 passes through the second central circular hole 901 on the side of the second right-angle connector 9. The second drive motor 6 is fixed to the side of the second right-angle connector 9 by screws at the four peripheral circular holes 902 on the side of the second right-angle connector 9.

[0062] like Figure 6 The second robotic arm 2 is a straight rod with parallel planes on opposite sides and arc-shaped ends. Each end of the second robotic arm 2 has a circular hole A201 and a circular hole B202, with their axes parallel and perpendicular to the sides of the straight rod. An end protrusion 203 is designed on the side wall of the end containing the circular hole B202. This end protrusion 203 has a fan-shaped structure, with its inner arc connecting to the circular hole B202 and its outer arc connecting to the arc at the end of the straight rod.

[0063] The structure of the third robotic arm 3 is similar to that of the second robotic arm 2. The difference is that the end of the third robotic arm 3 where the end hole B302 is located does not have an end protrusion structure; instead, a radial threaded hole 303 is opened at the end where the end hole A301 is located. The axis of the radial threaded hole 303 is radial along the end hole A301 of the third robotic arm and perpendicular to the axis of the third robotic arm 3.

[0064] The second robotic arm 2 is connected to the first through hole 803 on the side of the first right-angle connector 8 by a pin, forming a rotating pair C. The third robotic arm 3 is connected to the output shaft of the second drive motor 6 by a fitting hole A301, and is tightened and fixed by a set screw installed in the radial threaded hole 303 of the second robotic arm, forming a rotating pair D.

[0065] The fourth robotic arm 4 includes a robotic arm housing 401 and a motion module 402, such as Figure 8 As shown. The robotic arm housing 401 is assembled from an upper half 401a and a lower half 401b, with the connection method between the two parts being the same as that of the base housing 7. A semi-circular groove is designed at the corresponding position of the left rear end joint of the upper half 401a and the lower half 401b, forming a left rear circular hole 401c on the left rear end of the left side wall of the robotic arm housing 401 after assembly. A semi-cylindrical joint is designed at the right front end joint of the upper half 401a and the lower half 401b, with a coaxial semi-circular groove on the semi-cylindrical joint. An arc-shaped indentation is also designed along the outer circumference on the outer end face of the semi-cylindrical joint, forming a cylindrical joint 401d, a coaxial right front circular hole 401e on the cylindrical joint 401d, and an arc-shaped indentation 401f on the outer end face of the cylindrical joint 401d at the right front end of the robotic arm housing 401 after assembly. A semi-circular groove is designed in the middle of the joint between the front end faces of the upper half 401a and the lower half 401b of the box, so that a circular shaft hole is formed at the center of the front end face of the robotic arm box 401 after assembly.

[0066] like Figure 9 As shown, the motion module 402 is installed inside the fourth robotic arm 4, including a spline screw module 402a, a spline nut drive motor 402b, a screw nut drive motor 402c, a drive pulley A402d, a driven pulley A402e, a drive pulley B402f, a driven pulley B402g, a synchronous belt 402h, and an actuator connecting flange 402i.

[0067] Among them, the structure of the spline screw module 402a is as follows: Figure 10 As shown, the device includes a splined lead screw shaft 402a1 and splined nuts 402a2 and 402a3 connected to it via splines. These two nuts form a spline pair and a lead screw pair with the lead screw shaft 402a1, respectively. The splined nut 402a2 has a flange connected to its outer side via a bearing. The flange has six evenly distributed connecting holes A402a4 on its circumference. Simultaneously, the rear end face of the splined nut 402a2 has four evenly distributed threaded connecting holes A402a5 on its circumference. The lead screw nut 402a3 also has a flange connected to its outer side via a bearing. The flange also has six evenly distributed connecting holes B402a6 on its circumference. The front end face of the nut has four evenly distributed threaded connecting holes B402a7 on its circumference.

[0068] The aforementioned splined screw shaft 402a1 is connected to the robotic arm housing 401 via splined nuts 402a2 and the outer flanges of screw nuts 402a3. The upper and lower halves of the splined nut 402a2 are respectively placed in positioning grooves 401k located at the junction of the upper connecting plate A401g and the lower connecting plate A401i within the lower half 401b of the housing, and are fixed to the upper connecting plate A401g and the lower connecting plate A401i via six connecting holes A402a4 on the flange using screws. Figure 11 As shown. Similarly, the upper and lower halves of the lead screw nut 402a3 are respectively placed in the positioning grooves 401k at the junction of the upper connecting plate B401h and the lower connecting plate B401j designed in the lower half of the housing 401b, and are fixed to the upper connecting plate B401h and the lower connecting plate B401j by screws through the six connecting holes B402a6 on the flange.

[0069] Spline nut 402a2 and lead screw nut 402a3 are driven by spline nut drive motor 402b and lead screw nut drive motor 402c, respectively. Figure 9 As shown. The spline nut drive motor 402b is fixed to the upper connecting plate A401g with screws. Its output shaft passes through the connecting plate shaft hole A401m on the upper connecting plate A401g and is coaxially fixed to the drive pulley A402d via a set screw. The drive pulley A402d is connected to the driven pulley A402e via a synchronous belt 402h. The driven pulley A402e is fitted onto the spline screw shaft 402a1 and fixed with screws in the connecting threaded hole A402a5 on the rear end face of the spline nut 402a2. Thus, the motion output from the shaft of the spline nut drive motor 402b can be transmitted to the spline nut 402a2 via the drive pulley A402d, the synchronous belt 402h, and the driven pulley A402e.

[0070] The lead screw and nut drive motor 401b is fixed to the upper connecting plate B401h with screws. Its output shaft passes through the shaft hole A401n in the upper connecting plate and is coaxially fixed to the drive pulley B402f with a set screw. The drive pulley B402f is connected to the driven pulley B402g via a synchronous belt 402h. The driven pulley B402g is fitted onto the splined lead screw shaft 402a1 and is connected to the lead screw nut 402a3 via a screw and a threaded hole B402a7 on the front end face of the lead screw nut 402a3. Thus, the motion output from the shaft of the lead screw and nut drive motor 401c is transmitted to the lead screw nut 402a3 via the drive pulley B402g, the synchronous belt 402h, and the driven pulley B402g.

[0071] The aforementioned upper connecting plate A401g and upper connecting plate B401h are further connected and fixed by bolts through upper connecting shoulders 401p designed on the side walls at both ends of their respective bottom edges and lower connecting shoulders 401q designed on both sides of the inner wall of the lower half of the housing 401b. After installing the aforementioned spline screw shaft 402, the upper half of the housing 401a can be installed, so that the two upper connecting plates are located inside the upper half of the housing 401a, and the upper and lower parts of the housing are further connected and fixed by bolts.

[0072] The front end of the aforementioned splined screw shaft 402a1 passes through the circular shaft hole at the front end of the robotic arm housing 401, and the end is fitted with an actuator connecting flange 402i for connecting an actuator, such as a gripper. The output motion and motor drive method of the splined screw shaft 402a1 are as follows:

[0073] When the spline nut drive motor 402b drives the spline nut 402a2 to rotate, and the spline nut drive motor 402c does not drive the lead screw nut 402a2, the spline lead screw shaft 402a1 outputs helical motion. When the lead screw nut drive motor 402c drives the lead screw nut 402a3 to rotate, and the spline nut drive motor 402b does not drive the spline nut 402a2, the spline lead screw shaft 402a1 outputs pure translational motion along the axial direction. When the spline nut drive motor 402b drives the spline nut 402a2 to rotate, and the lead screw nut drive motor 402c drives the lead screw nut 402a3 to rotate at the same angular velocity, the spline lead screw shaft 402a1 outputs pure rotational motion. Therefore, the motion module 402 can enable the spline lead screw shaft 402 to output two degrees of freedom of rotation and translation through different driving methods.

[0074] The fourth robotic arm 4 of the above structure is connected to the third robotic arm 3 via a pin through a left rear circular hole 401c on the left rear side of the left side wall of the robotic arm housing 401 and a third robotic arm end circular hole B302, forming a revolute joint F. Simultaneously, the right front circular hole 401e on the right front side of the robotic arm housing 401 is connected to the second robotic arm 3 via a pin, forming a revolute joint E. Furthermore, the end protrusion 203 on the second robotic arm 2 is embedded in the arc-shaped recess 401f on the outer end face of the cylindrical joint on the right front side of the robotic arm housing 401, forming a mechanical limit for the revolute joint E.

[0075] The lengths of the first robotic arm 1, the second robotic arm 2, the third robotic arm 3, and the fourth robotic arm 4 are all equal. The first robotic arm 1, the second robotic arm 2, the third robotic arm 3, and the fourth robotic arm 4 are connected by a revolute joint AF and two right-angle connectors to form a 6R mechanism, so that the fourth robotic arm 4 has two degrees of freedom relative to the first robotic arm 1, namely rotation and translation.

[0076] By combining the two-degree-of-freedom (DOF) rotational and translational motion output from the aforementioned splined screw shaft 402a with the two-DOF rotational and translational motion of the fourth robotic arm 4 relative to the first robotic arm 1, a four-degree-of-freedom (DOF) motion of the actuator connecting flange 402i at the end of the splined screw shaft 402a relative to the first robotic arm 1 can be generated. Through different geometric configurations between the robot joints of this invention, this four-degree-of-freedom motion has two different forms, generating the robot's... The sports mode and remote center sports mode are as follows:

[0077] The robot is in Joint arrangement during motion mode, such as Figure 12 As shown. In this joint configuration, the axes of revolute joint A and revolute joint B coincide, and the axes of motion of revolute joints C, D, E, and revolute joint F are all parallel to each other. For kinematic joint E, there is no mechanical limit or contact at this time, and it does not restrict the robot's motion. As mentioned earlier, the spline screw shaft 402a and its end actuator connecting flange 402i have rotational degrees of freedom relative to the fourth robotic arm 4 and translational degrees of freedom along the rotation axis, and as... Figure 12 The joint arrangement shown indicates that during the robot's motion, the rotation axis of the spline screw shaft 402a is always parallel to the common axis of revolute joints A and B. Through kinematic analysis, it can be determined that the final motion output by the actuator connecting flange 402i at the front end of the spline screw shaft 402a in the fourth robotic arm 4 relative to the base box 7 is a four-degree-of-freedom motion with three translations and one rotation, and the rotation direction is always parallel to the common axis of revolute joints A and B during the motion. The robot's operating space under this motion mode is as follows: Figure 13 As shown, its shape is a hollow cylinder 10 with the common axis of revolute joints A and B as its axis. The actuator connecting flange 402i at the end of the robot can move in three dimensions within this cylindrical space 10 and achieve rotational motion along the axis of the cylinder 10 at any position, realizing... Motion mode. This motion mode is the same as that of SCARA robots widely used in industrial production assembly, making it ideal for tasks such as planar handling and assembly of workpieces.

[0078] like Figure 14 As shown, when the robot moves from the aforementioned 3-step movement and 1-step rotation... When the motion mode reaches the bifurcation point, the motion axes of revolute joints D and E coincide, causing a sudden change in the robot's degrees of freedom. At this point, the robot will exhibit two different motion mode tendencies. For example... Figure 15As shown, when the robot moves to the bifurcation configuration, the end protrusion 203 of the mechanical limiter at the revolute joint E will engage with the arc-shaped recess 401f. Therefore, in this configuration, when the second drive motor 6 drives the revolute joint D to rotate clockwise, the rotation of the revolute joint E is restricted, preventing it from rotating counterclockwise to keep the axes of motion of the revolute joints D and E aligned. In motion mode, the axes of the two rotary joints are separated and always parallel. Rotary joint E will rotate clockwise together with rotary joint D, thus entering the remote center motion mode of 3 rotations and 1 shift.

[0079] like Figure 16 As shown, when the rotary joint E rotates clockwise following the rotary joint D, the end protrusion 203 of the mechanical limit 203 at the kinematic joint E disengages from the arc-shaped recess 401f, thus no longer restricting the robot's movement. At this time, the fourth robotic arm 4 has two rotational degrees of freedom relative to the base box 7. The first rotational axis is the common axis of rotary joints A and B, and the second rotational axis is the coincident axis of rotary joints D and E. The two rotational axes are perpendicularly orthogonal at point O. Simultaneously, the rotational axis of the spline screw shaft 402a in the fourth robotic arm 4 will also intersect the above two axes at point O. Therefore, the motion mode of the actuator connecting flange 402i at the end of the robot end and the spline screw shaft 402a is a combination of three-dimensional rotational motion around the common intersection point O of the three rotational axes and translational motion along the direction of the third rotational axis, resulting in a four-degree-of-freedom motion of 3 rotations and 1 translation. The robot's workspace under this motion mode is... Figure 16 The hollow sphere 11 shown has its center at the common intersection point O of the three rotation axes. This operating mode of the robot is the same as the motion mode of the fixed-center motion mechanism of the Da Vinci robot, which is also a three-dimensional rotation around a certain point and radial movement along that point, and has application potential in the field of minimally invasive surgical robots.

Claims

1. A metacellular robot with remote center motion and Schönflies motion modes, characterized in that: The system includes a first robotic arm, a second robotic arm, a third robotic arm, a fourth robotic arm, and a motion module. A first drive motor is installed at the front end of the first robotic arm. The inner side of a first right-angle connector faces the first robotic arm, and one side is fixedly connected to the output shaft of the first drive motor, forming a revolute joint A. The outer side of a second right-angle connector faces the first robotic arm, and one side is connected to the rear end of the first robotic arm, forming a revolute joint B. The other side of the first right-angle connector is connected to one end of the second robotic arm, forming a revolute joint C. A second drive motor is installed on the other side of the second right-angle connector, and the output shaft of the second drive motor is fixedly connected to one end of the third robotic arm, forming a revolute joint D. The other ends of the second and third robotic arms are respectively connected to the front and rear ends of the fourth robotic arm, forming revolute joints E and F, respectively. This allows the fourth robotic arm to have two degrees of freedom relative to the first robotic arm—rotation and translation. A mechanical limit is designed at the aforementioned motion joint E. The fourth robotic arm is internally equipped with a motion module; the motion module includes a spline screw module and a drive mechanism; wherein, the spline screw module includes a spline screw shaft and a spline nut and a screw nut connected to the screw pair via a spline pair; the spline nut and the screw nut are driven by the drive mechanism to rotate individually or together; the front end of the spline screw shaft protrudes through the front end face of the fourth robotic arm, and the end is designed with an actuator connection flange; when the spline nut is driven to rotate alone, the spline screw shaft outputs helical motion; when the screw nut is driven to rotate alone, the spline screw shaft outputs helical motion. The lead screw shaft outputs pure translational motion along the axial direction; when the spline nut and lead screw nut are synchronously driven to rotate, the spline screw shaft outputs pure rotational motion, resulting in a two-degree-of-freedom motion of one rotation and one translation. Combined with the aforementioned two-degree-of-freedom rotational and translational motion of the fourth robotic arm relative to the first robotic arm, a four-degree-of-freedom motion of the spline screw shaft end actuator connecting flange relative to the first robotic arm is obtained. This four-degree-of-freedom motion has two different forms, generating the robot's Schönflies motion and remote center motion mode, specifically: When the robot is in Schönflies motion mode, the axes of revolute joint A and revolute joint B coincide, and the motion axes of revolute joints C, D, E, and revolute joint F are all parallel to each other. At this time, the mechanical limit at revolute joint E does not make contact. The spline screw shaft and its end actuator connecting flange have rotational and translational degrees of freedom relative to the fourth robot arm, and the rotational axis of the spline screw shaft is always parallel to the common axis of revolute joints A and B. Therefore, the final motion output by the actuator connecting flange at the end of the spline screw shaft in the fourth robot arm relative to the first robot arm is a four-degree-of-freedom motion of 3 translations and 1 rotation, and the rotational direction is always parallel to the common axis of revolute joints B and C during the motion. In this motion mode, the robot's operating space is a hollow cylinder with the common axis of revolute joints A and B as its axis. When the robot moves from the aforementioned 3-transfer 1-rotation Schönflies motion mode to the motion bifurcation point, the motion axes of rotary joints D and E coincide, and the robot has two different motion mode tendencies. When the robot moves to the bifurcation configuration, the mechanical limiting contact at rotary joint E, when the second drive motor drives rotary joint D to rotate clockwise, the rotation of rotary joint E is restricted, so that the motion axes of rotary joints D and E remain coincident, and rotary joint E will follow rotary joint D to rotate clockwise, thus entering the 3-rotation 1-transfer remote center motion mode. When the revolute joint E rotates clockwise following the revolute joint D, the mechanical limit at the kinematic joint E is released. At this time, the fourth robotic arm has two rotational degrees of freedom relative to the first robotic arm. The first rotational axis is the common axis of revolute joints A and B, and the second rotational axis is the coincident axis of revolute joints D and E. The two rotational axes are perpendicular and orthogonal at a point O. At the same time, the rotational axis of the spline screw shaft in the fourth robotic arm will also intersect the above two axes at point O. Therefore, the motion mode of the actuator connecting flange at the end of the robot and the end of the spline screw shaft is a combination of three-dimensional rotational motion around the common intersection point O of the three rotational axes and translational motion along the direction of the third rotational axis, which is a four-degree-of-freedom motion of 3 rotations and 1 translation. In this motion mode, the robot's workspace is a hollow sphere, and the center of the sphere is the common intersection point O of the three rotational axes.

2. The morphological robot with remote center motion and Schönflies motion modes as described in claim 1, characterized in that: The first robotic arm is a box structure consisting of an upper box and a lower box. The upper and lower boxes are designed with matching shoulders on their sides, which are connected and fixed together by bolts and through holes evenly distributed on the shoulders.

3. The morphological robot with remote center motion and Schönflies motion modes as described in claim 1, characterized in that: The first right-angle connector has openings on both sides for connecting the motor and the robotic arm, with the axes of the openings perpendicularly orthogonal at 90°; the second right-angle connector actually has openings on both sides for connecting the robotic arm, with the axes of the openings perpendicularly orthogonal at 90°.

4. The metacellular robot with remote center motion and Schönflies motion modes as described in claim 1, characterized in that: The fourth robotic arm housing is assembled from an upper half and a lower half. The upper and lower halves of the housing have mating shoulders on their sides, which are connected and fixed together by bolts and evenly distributed through holes on the shoulders. Two lower connecting plates are designed at the front and rear positions inside the lower half of the housing. An upper connecting plate is fixed above the two lower connecting plates by screws. The front lower connecting plate has slots on its opposite sides to accommodate spline nuts, and is fixed to both the upper and lower connecting plates via a flange structure designed around the spline nuts. The rear lower connecting plate has slots on its opposite sides to accommodate lead screw nuts, and is fixed to both the upper and lower connecting plates via a flange structure designed around the lead screw nuts.

5. A metacellular robot with remote center motion and Schönflies motion modes as described in claim 1, characterized in that: The drive mechanism includes two sets of belt drive mechanisms, which are used to drive the spline nut and the lead screw nut to rotate respectively. In the two sets of belt drive mechanisms, the driven pulley is sleeved on the spline lead screw shaft and is fixedly connected to the end face of the spline nut and the lead screw nut respectively. The two driven pulleys are respectively sleeved on the drive pulleys through the conveyor belt. The two drive pulleys are coaxially fixed on the output shaft of the drive motor. The two drive motors are fixed inside the fourth robotic arm.

6. The morphomorphic robot with remote center motion and Schönflies motion modes as described in claim 1, characterized in that: The second robotic arm has a protrusion at its end and a recess at the end of its housing; the two work together to achieve mechanical limiting of the rotary joint E.

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