Multi-degree-of-freedom robot and control method therefor

Abstract

The present invention relates to a multi-degree-of-freedom robot, comprising a first joint, a second joint, a third joint and an end effector assembly, which are connected in sequence, wherein each of the first joint, the second joint, the third joint and the end effector assembly at least comprises a linear electric motor and a mounting plate configured to mount the linear electric motor, and at least one of the first joint, the second joint and the third joint further comprises a rotating electric motor. The three joints of the robot can not only implement linear motion in the directions of three axes, but also implement rotary motion in at least one direction, ultimately allowing the end effector assembly to move more flexibly and reach a lesion position more easily.

Description

A multi-degree-of-freedom robot and its control method Technical Field

[0001] The present invention relates to the field of medical robots, and more particularly, to a multi-degree-of-freedom robot and a control method thereof. Background Art

[0002] With the development of automation technology, various automated auxiliary equipment such as robots have been applied to various industries. For example, in the medical industry, there are various auxiliary equipment such as surgical robots, such as abdominal surgery robots and orthopedic surgery robots.

[0003] Existing surgical robots are equipped with multiple joints, generally with more than three joints, to ensure that the surgical robot can drive the end effector to move flexibly during the operation. However, the joints of surgical robots at this stage often adopt the form of linear motors or rotary motors. The linear motor allows different joints to perform linear motion in the X-axis, Y-axis and Z-axis directions to control the movement of the end effector, while the rotary motor allows the joints to perform rotational motion in the X-axis, Y-axis and Z-axis directions to control the movement of the end effector. Regardless of which of the above forms is used, the degree of freedom for the robot's movement will still be insufficient, and the flexibility of the surgical robot still needs to be improved.

[0004] With the development of automation technology, various automated auxiliary equipment such as robots have been applied to various industries. For example, in the medical industry, there are various auxiliary equipment such as surgical robots, such as abdominal surgery robots and orthopedic surgery robots.

[0005] Existing surgical robots are equipped with multiple joints, typically six or more, to ensure flexible movement of the end effector during surgery. Generally speaking, surgical robot designs often utilize a series-connected structure with multiple rotary motors to provide linear spatial freedom at the end effector. In addition, a wrist-type structure driven by a cable, wire, or hinge provides flexible rotation and swivel of the tool. However, robots based on these designs have certain drawbacks in microsurgery applications. First, the series connection of multiple rotary motors results in load accumulation, resulting in a relatively large overall robotic arm design that cannot effectively accommodate the confined working space under a microscope during microsurgery. Second, the use of a wrist-type structure driven by a cable, wire, or hinge to provide flexible tool swivel cannot reliably guarantee drive accuracy. Furthermore, the size of instruments used in microsurgery is much smaller than those used in general surgery (typically less than 3 mm, with the end effector reaching 0.05-0.1 mm). Therefore, the ultra-small production of wrist-type structures driven by a cable, wire, or hinge is highly challenging. Last but not least, some miniaturized robots, such as ophthalmic surgical robots, use parallelogram or linear motor parallel designs. Although these mechanisms can meet the requirements of microsurgery in terms of size and precision, they lack a wrist structure to provide flexible swing angles for the tools, resulting in insufficient flexibility in the terminal degrees of freedom and unable to meet the requirements of complex movements such as suturing and knotting in microsurgery. Summary of the Invention

[0006] In order to overcome the problem of poor flexibility of surgical robots in the above-mentioned prior art, the present invention provides a multi-degree-of-freedom robot that can allow the end effector to perform linear motion and rotational motion in three axes simultaneously.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is: a multi-degree-of-freedom robot, comprising a first joint, a second joint, a third joint and an end effector assembly connected in sequence; the first joint, the second joint, the third joint and the end effector assembly each include at least one linear motor and a mounting plate for installing the linear motor; at least one joint among the first joint, the second joint and the third joint also includes a rotary motor.

[0008] In the above technical solution, each joint has a linear motor. When each linear motor's linear motion direction is set to different and perpendicular to each other, linear motion in three directions can be achieved. The rotary motor can further enable at least one joint to rotate, increasing the flexibility of the robot's joints. Furthermore, the linear motors can also have the same motion direction, increasing the robot's range of motion in one direction.

[0009] Preferably, a damper is mounted on the mounting plate corresponding to the linear motor whose output shaft is parallel to the direction of gravity of the end effector assembly, and the output end of the damper is connected to the output end of the linear motor. More preferably, the damper is a coil spring. A linear motor whose output shaft is parallel to the direction of gravity of the end effector assembly will experience significant gravity interference due to the influence of the gravity of the end effector assembly. At the same time, if the linear motor is located at the third joint, the joint is equivalent to a slender connecting rod between the first rotary motor and the second rotary motor and their load, and is subject to a large inertial torque. Therefore, in use, to avoid joint tremor, reduced positioning accuracy, or motor wear, the damper, that is, the coil spring, has its elastic force direction set opposite to the direction of gravity of the end effector assembly. When the linear motor moves, the coil spring can provide a constant force output to balance the vertical load on the third linear motor. Thanks to the coil spring's leaf-following mechanism, this design ensures that the gravity compensation output force is aligned with the third linear motor, thus preventing the direction of the compensation force from changing, which could cause deformation and damage to the coil spring and prevent forces from being applied to the linear motor in other directions. It should be noted that the output force K of the constant-force spring is preset to 2N. This value is calculated based on the motor's rated thrust T, the expected maximum operating force A, and the load gravity G. It can be adjusted appropriately based on the above parameters. The range of K values ​​is calculated as follows:

[0010] Preferably, the first joint includes a first mounting plate and a first linear motor connected to the first mounting plate; the second joint includes a second mounting plate connected to the output end of the first linear motor, a second linear motor connected to the second mounting plate, a first mounting member connected to the output end of the second linear motor, and a first rotary motor mounted on the first mounting member; the third joint includes a third mounting plate connected to the output end of the first rotary motor, a third linear motor connected to the third mounting plate, a second mounting member connected to the output end of the third linear motor, and a second rotary motor connected to the second mounting member; the connecting member is connected to the output end of the first rotary motor. The output shafts of the second linear motor and the first linear motor are perpendicular to each other, and the output shaft of the third linear motor is perpendicular to the output shafts of the second linear motor and the first linear motor; the rotation axis of the first rotary motor is perpendicular to the output shaft of the second linear motor, the rotation axis of the second rotary motor is perpendicular to the output shaft of the third linear motor, and the output shaft of the third linear motor is parallel to the direction of gravity of the end effector assembly. The first linear motor, the second linear motor, and the third linear motor allow the actuator mechanism to translate in the three directions of X, Y, and Z, respectively. The first rotary motor and the second rotary motor provide two degrees of rotational freedom in addition to the three directions of translation, allowing the robot's motion joints to achieve more flexible movement. The third linear motor is a linear motor whose output shaft is parallel to the direction of gravity of the end effector assembly. Its load is the second rotary motor and the end effector assembly, which makes the load on the third linear motor relatively less. If the third linear motor is changed to the first linear motor or the second linear motor, then the load will be greater, and it will also need to bear the load of the second joint and / or the third joint.

[0011] Preferably, the end effector assembly includes a connector mounted on the output end of the second rotary motor, a fourth linear motor mounted on the connector, an end mounting base mounted on the output end of the fourth linear motor, and an actuator mechanism mounted on the end mounting base; the actuator mechanism includes an actuator, an end motor base mounted on the end mounting base, and an instrument rotary motor mounted at the bottom of the end motor base; the actuator is connected to the output end of the instrument rotary motor. The fourth linear motor can be a linear motor, specifically a fourth linear motor.

[0012] Preferably, a counterweight is provided on a side of the third mounting plate away from the third linear motor, and a distance between the counterweight and the axis of the first rotary motor is D1 / 2, as follows:

[0013] Where D1 is the change in the moment arm acting on the first rotary motor; l4 is the displacement of the fourth linear motor; l0 is the displacement of the instrument linear motor; R2 is the rotation angle of the second rotary motor; and d is the initial value of the moment arm acting on the first rotary motor.

[0014] The rotational axes of the first and second rotary motors are arranged to be orthogonal to the axis of the end instrument. The second, third, fourth, and fourth linear motors, as well as the instrument rotary and linear motors, serve as the primary loads for the first rotary motor, and their centers of gravity are relatively far from the first rotary motor. Furthermore, the first rotary motor, as the primary posture rotation mechanism, is subject to a significant load gravitational torque. Furthermore, with its own rotation and the subsequent dynamic motion of the second, third, fourth, and fourth linear motors, the instrument rotary and linear motors, the torque acting on the first rotary motor is relatively unstable. The counterweight reduces the moment arm acting on the first rotary motor by 2 / 3 cm, thereby ensuring the stability of the overall structure and the smoothness of dynamic operation.

[0015] Preferably, the third mounting plate is L-shaped, the first side plate of the third mounting plate is connected to the output end of the first rotary motor, and the second side plate is used to install the third linear motor; the counterweight block is installed at one end of the first side plate away from the second side plate.

[0016] Preferably, the actuator mechanism includes an end motor mount mounted on the end mounting base and an instrument rotary motor mounted at the bottom of the end motor mount; the actuator is connected to the output end of the instrument rotary motor. The instrument rotary motor drives the actuator to rotate. The rotation of the actuator does not cause relative displacement between the end and the camera module, thereby ensuring the accuracy of image capture by the camera module. The instrument rotary motor allows the actuator to move more flexibly, making it easier to align the actuator with tissue lesions, etc.

[0017] Preferably, the instrument rotary motor is a hollow motor; the actuator mechanism further comprises an instrument linear motor mounted on the end motor mount and a push rod mounted at the output end of the instrument linear motor; the push rod extends through the end motor mount and the hollow motor into the actuator and is used to push the actuator to open or close. When the actuator is a surgical instrument such as microtweezers or scissors, to enable the remote controller to open and close the end, the instrument linear motor drives the push rod to extend into the actuator to push it open or close.

[0018] Preferably, the instrument rotary motor is connected to the actuator through an instrument mounting seat; the actuator is detachably connected to the instrument mounting seat. Since actuators need to be replaced frequently, if the actuator is directly connected to the instrument rotary motor, the output end of the instrument rotary motor needs to be operated every time it is disassembled, which can easily affect its lifespan, and it is also very inconvenient to disassemble and assemble fasteners, especially in an operating room environment where necessary disassembly and assembly tools are lacking. After adding an instrument mounting seat, the instrument mounting seat can be connected to the output end of the instrument rotary motor through fasteners, and the actuator only needs to be snap-connected or threaded to the instrument mounting seat, which makes replacement of the actuator more convenient and does not require frequent disassembly of the instrument rotary motor.

[0019] Preferably, a camera module is also installed on the end mounting seat, and the imaging axis of the camera module is parallel to the axis of the actuator, and the focus of the camera module is located on a plane perpendicular to the end of the actuator. Since the camera model and the actuator assembly are both mounted on the end mounting seat, the camera model and the actuator assembly are always in a state of moving together, so that the robot can have dynamic vision and always maintain a focused state, so that no matter which direction the actuator moves, the camera module can capture an image in the direction of the actuator. At the same time, since the actuator assembly and the motion model are independently mounted on the end mounting seat, the two will not interfere with each other, and the camera module will not hinder the movement of the actuator assembly. Since the camera module and the end of the actuator are in a relatively static state, the camera module can always focus on the end of the actuator, so that no matter how the actuator moves, the camera module can capture a clear image of the end of the actuator.

[0020] Preferably, there are two first linear motors installed side by side on the first mounting plate. Since the first linear motor has the largest load, sufficient thrust can be generated at the first joint by the two first linear motors.

[0021] Preferably, the movement directions of the first linear motor, the second linear motor, and the third linear motor are orthogonal to each other; the first linear motor and the second linear motor are both orthogonal to the rotation axis of the first rotary motor; the movement axis of the third linear motor is parallel to the rotation axis of the first rotary motor; the movement axes of the third linear motor and the fourth linear motor are orthogonal to the rotation axis of the second rotary motor; the rotation axes of the first rotary motor, the second rotary motor, and the instrument rotary motor intersect at the point and the point is located on the axis of the execution device. The drive of the first linear motor, the second linear motor, the third linear motor, the fourth linear motor, the first rotary motor, the second rotary motor, and the instrument rotary motor, a total of 7 degrees of freedom, x, y, z, tool axis, roll angle (roll), pitch angle (pitch), yaw angle (yaw), are all transmitted to the axis center O of the end tool without any theoretical loss:

[0022] Compared with the existing technology, the beneficial effects are: the three joints of the robot can not only realize linear motion in three-axis directions, but also realize rotational motion in at least one direction, and these motions are transmitted losslessly from the corresponding drive motor to the tool axis through effective structural design, ultimately making the movement of the end effector assembly more flexible and easier to reach the lesion location.

[0023] (2) Benefiting from the special combination of linear and rotary motors, the mechanism can achieve three-axis translation and virtual fixed-point control in multiple planes in a variety of driving modes, ultimately allowing the end effector assembly to achieve a virtual wrist joint motion with higher precision and smaller size than rope drive, wire or hinge drive. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] FIG1 is a perspective view of a multi-degree-of-freedom robot of the present invention;

[0025] FIG2 is an exploded view of the first joint, the second joint, and the third joint of the present invention;

[0026] FIG3 is a schematic structural diagram of a third joint of the present invention;

[0027] FIG4 is an exploded view of the end effector assembly of the present invention;

[0028] 5 is a diagram showing the positional relationship among the first linear motor, the second linear motor, the third linear motor, the fourth linear motor, the first rotary motor, the second rotary motor, and the instrument rotary motor of the multi-degree-of-freedom robot of the present invention;

[0029] FIG6 is a schematic diagram of a first virtual wrist joint of the present invention;

[0030] FIG7 is a schematic diagram of a second virtual wrist joint of the present invention;

[0031] FIG8 is another schematic diagram of the first virtual wrist joint of the present invention;

[0032] FIG9 is another schematic diagram of the second virtual wrist joint of the present invention. DETAILED DESCRIPTION

[0033] The drawings are for illustrative purposes only and should not be construed as limiting this patent. To better illustrate the embodiments, some components in the drawings may be omitted, enlarged, or reduced in size, and do not represent actual product dimensions. Those skilled in the art will understand that some well-known structures and their descriptions may be omitted from the drawings. The positional relationships depicted in the drawings are for illustrative purposes only and should not be construed as limiting this patent.

[0034] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "long", "short", etc. indicating the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0035] The technical solution of the present invention is further described in detail below through specific embodiments and in conjunction with the accompanying drawings:

[0036] Example 1

[0037] Figures 1-3 illustrate a multi-degree-of-freedom robot embodiment 1, comprising a first joint 1, a second joint 2, a third joint 3, and an end effector assembly 4, connected in sequence. Each of the first joint 1, the second joint 2, the third joint 3, and the end effector assembly 4 includes at least one linear motor and a mounting plate for the linear motor. At least one of the first joint 1, the second joint 2, and the third joint 3 also includes a rotary motor. A damper 5 is mounted on the mounting plate corresponding to the linear motor, whose output shaft is parallel to the direction of gravity of the end effector assembly 4. The output end of the damper 5 is connected to the output end of the linear motor. In this embodiment, the damper 5 is a coil spring.

[0038] Specifically, the first joint 1 includes a first mounting plate 101 and a first linear motor 102 connected to the first mounting plate 101. In this embodiment, two first linear motors 102 are provided and arranged side by side; the second joint 2 includes a second mounting plate 201 connected to the output end of the first linear motor 102, a second linear motor 202 connected to the second mounting plate 201, a first mounting member 203 connected to the output end of the second linear motor 202, and a first rotary motor 204 mounted on the first mounting member 203; the third joint 3 includes a third mounting plate 301 connected to the output end of the first rotary motor 204, a third linear motor 302 connected to the third mounting plate 301, a second mounting member 303 connected to the output end of the third linear motor 302, and a second rotary motor 304 connected to the second mounting member 303; the connecting member 401 is connected to the output end of the second rotary motor 304. The output axes of the second linear motor 202 and the first linear motor 102 are perpendicular to each other, and the output axes of the third linear motor 302 are both perpendicular to the output axes of the second linear motor 202 and the first linear motor 102. The rotation axis of the first rotary motor 204 is perpendicular to the output axis of the second linear motor 202, and the rotation axis of the second rotary motor 304 is perpendicular to the output axis of the third linear motor 302. The output axis of the third linear motor 302 is parallel to the direction of gravity of the end effector assembly 4. The first linear motor 102, the second linear motor 202, and the third linear motor 302 respectively enable translation of the actuator mechanism in the X, Y, and Z axes. In addition to the three translational axes, the first rotary motor 204 and the second rotary motor 304 provide two rotational degrees of freedom, enabling more flexible movement of the robot's kinematic joints. In this embodiment, the third linear motor 302 is a linear motor with an output shaft parallel to the direction of gravity of the end effector assembly 4. A coil spring is fixedly mounted on the third mounting plate 301 via a fixing base 305, located on the side near the first rotary motor 204. The active end of the coil spring is connected to the output end of the third linear motor 302. In this embodiment, the active end of the coil spring is fixedly connected to the second mounting member 303. Due to the influence of gravity on the end effector assembly 4, the third linear motor is subject to significant gravitational interference. Furthermore, if this linear motor is located at the third joint 3, the joint is equivalent to a slender connecting rod between the first rotary motor 204, the second rotary motor 304, and their load, subjecting it to significant inertial torque. Therefore, to avoid joint vibration, reduced positioning accuracy, or motor wear during use, the damper 5, or coil spring, is configured with its elastic force directed opposite to the direction of gravity of the end effector assembly 4. This allows the coil spring to provide a constant force output when the linear motor moves, balancing the vertical load on the third linear motor 302.Thanks to the coil spring's leaf-following design, this design ensures that the gravity compensation output force is aligned with the third linear motor 302, thus preventing the direction of the compensation force from changing, which could cause deformation and damage to the coil spring and apply forces in other directions to the linear motor. It should be noted that the output force K of the constant-force spring is preset to 2N. This value is calculated based on the motor's rated thrust T, the expected maximum operating force A, and the load gravity G. It can be adjusted appropriately based on these parameters. The range of K values ​​is calculated as follows:

[0039] The operating principle or workflow of this embodiment is as follows: The first joint 1, second joint 2, and third joint 3 perform linear motion in three axes, driving the end effector assembly 4 to perform linear motion in three different directions. The first rotary motor 204 and second rotary motor 304 provide rotational motion in two directions, ultimately giving the end effector assembly 4 five degrees of freedom, enhancing its flexibility. The movement of the third linear motor 302 extends the coil spring, whose elastic force is in the opposite direction of the load force of the third linear motor 302, providing force compensation for the third linear motor 302.

[0040] The beneficial effects of this embodiment are as follows: The robot's three joints can achieve not only linear motion along three axes but also rotational motion in at least one direction, ultimately making the end effector assembly 4 more flexible and easier to reach the lesion. The damper 5 prevents vibration of the third joint 3, loss of positioning accuracy, or wear and tear of the third linear motor 302.

[0041] Example 2

[0042] Embodiment 2 of a multi-degree-of-freedom robot, based on embodiment 1, further defines the end effector assembly 4 and the third joint 3 as shown in FIG2-3 .

[0043] The end effector assembly 4 includes a connector 401 mounted on the output end of the second rotary motor 304, a fourth linear motor 402 mounted on the connector 401, an end mounting base 403 mounted on the output end of the fourth linear motor 402, and an actuator mechanism mounted on the end mounting base 403. The actuator mechanism includes an actuator 404, an end motor base 405 mounted on the end mounting base 403, and an instrument rotary motor 406 mounted at the bottom of the end motor base 405. The actuator 404 is connected to the output end of the instrument rotary motor 406. The fourth linear motor 402 can be a linear motor, specifically a fourth linear motor.

[0044] The actuator mechanism includes a terminal motor mount 405 mounted on the terminal mounting base 403 and an instrument rotation motor 406 mounted at the bottom of the terminal motor mount 405. The actuator 404 is connected to the output of the instrument rotation motor 406. The instrument rotation motor 406 drives the actuator 404 to rotate. This rotation of the actuator 404 does not cause relative displacement between the distal end and the camera module 7, thereby ensuring the accuracy of image capture by the camera module 7. The instrument rotation motor 406 allows for more flexible movement of the actuator 404, making it easier to align the actuator 404 with tissue lesions, etc.

[0045] Specifically, the instrument rotary motor 406 is a hollow motor. The actuator mechanism also includes an instrument linear motor 407 mounted on the end motor mount 405 and a push rod 408 mounted at the output end of the instrument linear motor 407. The push rod 408 extends through the end motor mount 405 and the hollow motor into the actuator 404 and is used to push the actuator 404 open and close. When the actuator 404 is a surgical instrument such as microtweezers or scissors, the instrument linear motor 407 drives the push rod 408 into the actuator 404 to push it open or close to enable remote control of the end opening and closing. The instrument rotary motor 406 is connected to the actuator 404 via the instrument mounting base 409; the actuator 404 and the instrument mounting base 409 are detachably connected. Since the actuator 404 needs to be replaced frequently, if the actuator 404 is directly connected to the instrument rotary motor 406, the output terminal of the instrument rotary motor 406 needs to be operated every time it is disassembled, which can easily shorten its lifespan. In addition, disassembling and assembling the fasteners is also very inconvenient, especially in an operating room environment where the necessary disassembly and assembly tools are lacking. By adding an instrument mounting base 409, the instrument mounting base 409 can be connected to the output terminal of the instrument rotary motor 406 via fasteners, and the actuator 404 only needs to be snap-fitted or threadedly connected to the instrument mounting base 409. This makes replacement of the actuator 404 more convenient and eliminates the need to frequently disassemble the instrument rotary motor 406.

[0046] Preferably, a counterweight 6 is provided on the side of the third mounting plate 301 away from the third linear motor 302, and the distance between the counterweight 6 and the axis of the first rotary motor 204 is D1 / 2, as follows:

[0047] Wherein, D1 is the change in the lever arm acting on the first rotary motor 204; l4 is the displacement of the fourth linear motor; l0 is the displacement of the instrument linear motor 407; R2 is the rotation angle of the second rotary motor 304; and d is the initial value of the lever arm acting on the first rotary motor 204.

[0048] The rotational axes of the first rotary motor 204 and the second rotary motor 304 are arranged to be orthogonal to the axis of the end effector. The second rotary motor 304, the third linear motor 302, the fourth linear motor, the instrument rotary motor 406, and the instrument linear motor 407 serve as the primary load for the first rotary motor 204, and their centers of gravity are relatively distant from the first rotary motor 204. Furthermore, the first rotary motor 204, as the primary posture rotation mechanism, is subject to a significant load gravitational torque. Furthermore, with its own rotation and the subsequent dynamic motion of the second rotary motor 304, the third linear motor 302, the fourth linear motor, the instrument rotary motor 406, and the instrument linear motor 407, the torque applied to the first rotary motor 204 is relatively unstable. However, the counterweight 6 reduces the moment arm acting on the first rotary motor 204 by 2 / 3 cm, thereby ensuring overall structural stability and smooth dynamic operation.

[0049] Furthermore, the third mounting plate 301 is L-shaped, the first side plate of the third mounting plate 301 is connected to the output end of the first rotary motor 204, and the second side plate is used to install the third linear motor 302; the counterweight block 6 is installed at one end of the first side plate away from the second side plate.

[0050] The remaining features and working principles of this embodiment are consistent with those of embodiment 1.

[0051] Example 3

[0052] Embodiment 3 of a multi-degree-of-freedom robot, based on embodiment 1 or embodiment 2, differs from embodiment 1 and embodiment 2 in that, as shown in FIG4 , a camera module 7 is also mounted on the end mounting seat 403. The imaging axis of camera module 7 is parallel to the axis of actuator 404, and the focal point of camera module 7 is located in a plane perpendicular to the end of actuator 404. Because the camera model and actuator assembly are both mounted on the end mounting seat 403, the camera model and actuator assembly are always in motion together, allowing the robot to have dynamic vision and maintain a focused state. Regardless of the direction of movement of actuator 404, camera module 7 can capture images in the direction of actuator 404. Furthermore, because the actuator assembly and motion model are independently mounted on the end mounting seat 403, they do not interfere with each other, and camera module 7 does not hinder the movement of the actuator assembly. Since the camera module 7 and the end of the actuator 404 are in a relatively static state, the camera module 7 can always focus on the end of the actuator 404, so that no matter any movement of the actuator 404, the camera module 7 can capture a clear image of the end of the actuator 404.

[0053] The remaining features and working principles of this embodiment are consistent with those of embodiment 1 or 2.

[0054] Example 4

[0055] Embodiment 4 of a multi-degree-of-freedom robot is based on any of the above embodiments and differs from any of the above embodiments in that, as shown in Figure 5, the first linear motor 102 and the second linear motor 202 are both orthogonal to the rotation axis of the first rotary motor 204; the motion axis of the third linear motor 302 is parallel to the rotation axis of the first rotary motor 204; the motion axes of the third linear motor 302 and the fourth linear motor 402 are orthogonal to the rotation axis of the second rotary motor 304; the rotation axes of the first rotary motor 204, the second rotary motor 304 and the instrument rotary motor 406 intersect at a point and the point is located on the axis of the execution instrument.

[0056] Existing surgical robots are equipped with multiple joints, typically six or more, to ensure flexible movement of the end effector during surgery. Generally speaking, surgical robot designs often utilize a series-connected structure with multiple rotary motors to provide linear spatial freedom at the end effector. In addition, a wrist-type structure driven by a cable, wire, or hinge provides flexible rotation and swivel of the tool. However, robots based on these designs have certain drawbacks in microsurgery applications. First, the series connection of multiple rotary motors results in load accumulation, resulting in a relatively large overall robotic arm design that cannot effectively accommodate the confined working space under a microscope during microsurgery. Second, the use of a wrist-type structure driven by a cable, wire, or hinge to provide flexible tool swivel cannot reliably guarantee drive accuracy. Furthermore, the size of instruments used in microsurgery is much smaller than those used in general surgery (typically less than 3 mm, with the end effector reaching 0.05-0.1 mm). Therefore, the ultra-small production of wrist-type structures driven by a cable, wire, or hinge is highly challenging. There are also some miniaturized robots, such as ophthalmic surgical robots, that use a parallelogram or linear motor parallel design. Although these mechanisms can meet the requirements of microsurgery in terms of size and precision, they lack a wrist structure to provide flexible swing angles for the tools, making them insufficiently flexible in terms of the end degrees of freedom and unable to meet the requirements of complex movements such as microsurgery suturing and knotting.

[0057] In this embodiment, as shown in FIG5 :

[0058] 1) Because the output shafts of the first and second linear motors are orthogonal to the rotation axis of the first rotary motor, and the base of the second linear motor is connected to the output shaft of the first linear motor, the x and y motions represented by the first and second linear motors, respectively, can be equivalently converged to any point on the rotation axis of the first rotary motor (i.e., the tool yaw angle);

[0059] 2) Since the output shaft of the third linear motor is parallel to the rotation axis of the first rotary motor, the z motion represented by the third linear motor can also be equivalently coincident with any point on the rotation axis of the first rotary motor;

[0060] 3) Because the output shaft of the second rotary motor is perpendicular to the output shaft of the third linear motor, the output shaft of the second rotary motor is equivalently perpendicular to the rotational axis of the first rotary motor. Because this structure sets the rotational axes of the first and second rotary motors to intersect at a point located on the axis of the actuator, the pitch angle represented by the second rotary motor can also be equivalently coincident with this point, which is located on the rotational axis of the first linear motor.

[0061] 4) This point is defined as point O; this point is on the rotation axis of the first rotary motor and intersects with the rotation axis of the second rotary motor. Because this structure sets the rotation axes (roll angle) of the first rotary motor, the second rotary motor, and the instrument rotary motor to intersect at this point, and this point is located on the axis of the actuator, the six degrees of freedom motion of x, y, z, roll, pitch, and yaw are transmitted at point O;

[0062] 5) Since the fourth linear motor is mounted on the rotation axis of the second rotary motor, and the output shaft of the fourth linear motor carries the end tool and is perpendicular to the rotation axis of the second rotary motor, the fourth linear motor can provide additional relative axial movement of the tool at point O.

[0063] Therefore, the distal surgical tool has the flexibility to be able to move in any direction and position within the stroke at point O.

[0064] The beneficial effect of this embodiment is that the drive of the first linear motor, the second linear motor, the third linear motor, the fourth linear motor and the first rotary motor, the second rotary motor, and the instrument rotary motor, totaling 7 degrees of freedom, including x, y, z, tool axis, roll angle (roll), pitch angle (pitch), and yaw angle, are all transmitted to the axis point O of the end tool without any theoretical loss. Therefore, the end surgical tool has the flexibility of being able to reach any direction and position within the stroke at point O.

[0065] The multi-degree-of-freedom robot of this embodiment can realize a miniaturized high-precision robot structure that works under a microscope, and on the basis of satisfying the linear spatial degrees of freedom, it can also realize the flexible rotation and swing angle of the virtual wrist structure at the end. The multi-degree-of-freedom robot provides three-axis translation and virtual fixed-point control with multiple driving modes on multiple axes. This technology can realistically follow the control of a virtual wrist structure of any length on the end tool, and can be converted into a fixed center point in space when needed to meet microsurgery scenarios such as vitreoretinal surgery that need to work around a fixed wound. As a result, the multi-degree-of-freedom robot of this embodiment can simultaneously meet the needs of open microsurgery (tissue cutting and anastomosis of lymphatic, venous and vascular tissues, etc.) and intracavitary microsurgery (such as vitreoretinal surgery performed by an ophthalmic surgical robot, etc.).

[0066] Example 5

[0067] An embodiment of a robot control method is used to implement control of the multi-degree-of-freedom robot of embodiment 4.

[0068] Based on the multi-degree-of-freedom robot in Example 4, the first virtual wrist joint driven by the first linear motor, the second linear motor and the first rotary motor is shown in FIG6 . The specific motion algorithm is:

[0069] Where X and Y are the orthogonal coordinate axes defined along the motion directions of the first and second linear motors, respectively, which are equivalent to the X and Y displacements at the first virtual wrist joint; α is the rotation axis defined along the rotation direction of the first rotary motor, which is equivalent to the yaw angle (yaw) at the first virtual wrist joint; θ2 is the current angle of the second rotary motor, and θ1 is the current angle of the first rotary motor; β is the defined virtual wrist joint (its value represents the distance between the virtual wrist joint and point O when the position of the fourth linear motor is 0); L1, L2, and L4 are the current positions of the first, second, and fourth linear motors, respectively.

[0070] When α rotates, the first and second linear motors perform the following motions:

[0071] Where, and are the movement speeds of the first linear motor and the second linear motor respectively, The X and Y displacements at the first virtual wrist joint point can be kept at 0, thereby achieving the first virtual wrist joint motion as shown in FIG6 .

[0072] Based on the multi-degree-of-freedom robot in Example 4, the second virtual wrist joint driven by the third linear motor, the fourth linear motor and the third rotary motor is shown in FIG7 . The specific motion algorithm is:

[0073] X' and Y' are the coordinate axes along the direction of motion of the third linear motor and the axis along which the fourth linear motor swings with the second rotary motor to a position orthogonal to the third linear motor, respectively. These axes are equivalent to the X' and Y' displacements at the second virtual wrist joint. α' is the rotation axis defined along the direction of rotation of the second rotary motor, equivalent to the pitch angle at the second virtual wrist joint. θ2 is the current angle of the second rotary motor. β is the defined virtual wrist joint (its value represents the distance between the virtual wrist joint and point O when the fourth linear motor is at position 0). L3 and L4 are the current positions of the third and fourth linear motors, respectively. It should be noted that the second virtual joint can be the same as the first virtual wrist joint, meaning both the second and first virtual wrist joints are β. This is difficult to achieve with traditional rope-driven, wire-driven, or hinge-driven wrist joints due to their size, structure, and transmission limitations.

[0074] When α' rotates, the first and second linear motors perform the following motions:

[0075] Where, and are the motion speeds of the third linear motor and the fourth linear motor respectively, The X' and Y' displacements at the second virtual wrist joint point can be kept at 0, thereby achieving the virtual wrist joint motion shown in FIG7 .

[0076] Based on the multi-degree-of-freedom robot of Example 4 and the constructed first virtual wrist joint and second virtual wrist joint, the specific control method is as follows:

[0077] Obtaining a position L1 of the first linear motor, a position L2 of the second linear motor, a position L3 of the third linear motor, a position L4 of the fourth linear motor, an angle θ1 of the first rotary motor, and an angle θ2 of the second rotary motor;

[0078] Define the virtual wrist joint point β (assuming that the two virtual wrist joint points use the same point on the tool), and obtain the distance Δ between the virtual wrist joint point β and the control transfer point O, specifically: Δ=β+L4

[0079] Based on a distance Δ between the virtual wrist joint point β and the control transfer point O, the motions of the first linear motor, the second linear motor, the third linear motor, the fourth linear motor, the first rotary motor, and the second rotary motor are combined into at least one linear motion generator and at least one rotary motion generator;

[0080] In this embodiment, the linear motion generator is specifically:

[0081] Where k1 is a parameter factor ranging from 0 to 1. When k1 = 0, linear movement is achieved solely by the first, second, and third linear motors. Benefiting from the fourth linear motor, the tool's axial motion intersects with the first, second, and third linear motors at point O. When k1 > 0, the fourth linear motor provides some compensation for linear movement, saving travel for the other linear motors, thanks to the flexibility of the end surgical tool at point O, which allows it to be moved in any direction and position within its travel range (i.e., the output shafts of the fourth linear motor, the first linear motor, the second linear motor, and the third linear motor all intersect equivalently at point 0).

[0082] In this embodiment, there are three rotational motion generators, namely a first virtual rotation generator, a second virtual rotation generator and a rotation generator;

[0083] The first virtual rotation generator is specifically:

[0084] The second virtual rotation generator is specifically:

[0085] The rotation generator is specifically:

[0086] Where Δ is the distance between the virtual wrist joint point β and the control transfer point O. It should be noted that for the sake of convenience, the first and second virtual rotation generators are assumed to use the same point β on the tool, i.e., both virtual rotation generators use the same parameter Δ. In practice, the second virtual rotation generator can be defined as a virtual wrist joint point β1 that is completely different from the first virtual rotation generator. The second virtual rotation generator remains unchanged, with only the parameter Δ changing (Δ1 = β1 + L4).

[0087] Where L4 is the current position of the fourth linear motor; θ1 and θ2 are the current angles of the first and second rotary motors; and Respectively represent the operating speeds of the first linear motor, the second linear motor, the third linear motor and the fourth linear motor for executing the linear motion generator; and The operating speed of the first linear motor and the second linear motor for executing the first virtual rotation generator; and The third linear motor and the fourth linear motor are used to execute the operating speed of the second virtual rotation generator.

[0088] x, y, x are the positions of the actuator on the coordinate axis; is the linear displacement speed of the actuator in the desired instruction; a and b are the rotation angles of the actuator; The rotation speed of the execution device in the expected instruction; is the rotation speed of the first rotating motor; is the rotation speed of the second rotating motor; is the rotation speed of the instrument's rotation motor.

[0089] Will expect instructions The output is input into the linear motion generator and the rotary motion generator, and the motion output of the first linear motor, the second linear motor, the third linear motor, the fourth linear motor, the first rotary motor and the second rotary motor is obtained by accumulating the output.

[0090] In this embodiment, based on the multi-degree-of-freedom robot of embodiment 4, the first virtual rotation generator and the second virtual rotation generator are configured to generate the same angle input. and With multiple options:

[0091] When the first rotary motor is at 90°, as shown in FIG8 , the first virtual rotation generator can be formed by combining the first linear motor and the fourth linear motor:

[0092] Similarly, when the first rotary motor is at 0°, the second linear motor and the fourth linear motor can be combined to form the first virtual rotation generator:

[0093] When the first rotary motor is at 90°, as shown in FIG9 , the second virtual rotary generator can be formed by combining the second linear motor and the third linear motor:

[0094] Similarly, when the first rotary motor is at 0°, the second virtual rotary generator can be formed by combining the first linear motor and the third linear motor:

[0095] The beneficial effects of this embodiment are as follows: Based on the multi-degree-of-freedom robot of embodiment 4, a virtual wrist structure can be formed by algorithm control based on the set positional relationship of the first linear motor, the second linear motor, the third linear motor, the fourth linear motor, the first rotary motor, the second rotary motor and the instrument rotary motor of the robot, which is exempted from mechanical structures such as rope drive and does not rely on the movement of mechanical mechanisms. Compared with traditional mechanical wrist joints, it has higher precision assurance, operational reliability (exempt from mechanical fatigue of rope drive) and lower production difficulty. Similarly, due to the movement flexibility of the multi-degree-of-freedom robot of embodiment 4, remote center movement of various types of wrist joints can be performed on multiple spatial axis planes.

[0096] In addition, based on the control method of this embodiment and the corresponding multi-degree-of-freedom robot, the linear motion generator is shielded, and the movement of the first virtual rotation generator, the second virtual rotation generator, the rotation generator and the fourth linear motor is utilized. At the same time, Δ is set to β, that is, the virtual rotation fixed point β is a fixed position set at a distance from point O along the tool direction, and does not move with the tool, that is, the intracavitary RCM movement around the wound or trocar fixed point can be realized (the axial movement of the tool in the cavity can be directly provided by the fourth linear motor).

[0097] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A multi-degree-of-freedom robot, comprising a first joint (1), a second joint (2), a third joint (3) and an end effector assembly (4) connected in sequence, characterized in that: The first joint (1), the second joint (2), the third joint (3) and the end effector assembly (4) each include at least one linear motor and a mounting plate for mounting the linear motor; at least one of the first joint (1), the second joint (2) and the third joint (3) also includes a rotary motor.

2. A multi-degree-of-freedom robot according to claim 1, characterized in that: A damper (5) is mounted on the mounting plate corresponding to the linear motor whose output shaft is parallel to the gravity direction of the end actuator assembly (4), and the output end of the damper (5) is connected to the output end of the linear motor.

3. A multi-degree-of-freedom robot according to claim 1, characterized in that: The first joint (1) comprises a first mounting plate (101) and a first linear motor (102) connected to the first mounting plate (101); the second joint (2) comprises a second mounting plate (201) connected to an output end of the first linear motor (102), a second linear motor (202) connected to the second mounting plate (201), a first mounting member (203) connected to an output end of the second linear motor (202), and a first rotary motor (204) mounted on the first mounting member (203); the third joint (3) comprises a third mounting plate (301) connected to an output end of the first rotary motor (204), a third linear motor (302) connected to the third mounting plate (301), a second mounting member (303) connected to an output end of the third linear motor (302), and a second rotary motor (304) connected to the second mounting member (303); the connecting member (401) is connected to an output end of the second rotary motor (304).

4. A multi-degree-of-freedom robot according to claim 3, characterized in that: The output axes of the second linear motor (202) and the first linear motor (102) are perpendicular to each other, and the output axes of the third linear motor (302) are perpendicular to the output axes of the second linear motor (202) and the first linear motor (102); the rotation axis of the first rotary motor (204) is perpendicular to the output axis of the second linear motor (202), and the rotation axis of the second rotary motor (304) is perpendicular to the output axis of the third linear motor (302); the output axis of the third linear motor (302) is parallel to the gravity direction of the end effector assembly (4).

5. A multi-degree-of-freedom robot according to claim 4, characterized in that: The end effector assembly (4) comprises a connecting piece (401) mounted on the output end of the second rotary motor (304), a fourth linear motor (402) mounted on the connecting piece (401), an end mounting seat (403) mounted on the output end of the fourth linear motor (402), and an actuator mechanism mounted on the end mounting seat (403); the actuator mechanism comprises an actuator (404), an end motor seat (405) mounted on the end mounting seat (403), and an instrument rotary motor (406) mounted at the bottom of the end motor seat (405); the actuator (404) is connected to the output end of the instrument rotary motor (406).

6. A multi-degree-of-freedom robot according to claim 5, characterized in that: A counterweight block (6) is provided on a side of the third mounting plate (301) away from the third linear motor (302), and the distance between the counterweight block (6) and the axis of the first rotating motor (204) is D1 / 2, as follows: In the formula, D1 is the change value of the force arm received by the first rotating motor (204); l4 is the displacement of the fourth linear motor; l0 is the displacement of the instrument linear motor (407); R2 is the rotation angle of the second rotating motor (304); and d is the initial value of the force arm received by the first rotating motor (204).

7. A multi-degree-of-freedom robot according to claim 6, characterized in that: The third mounting plate (301) is L-shaped, the first side plate of the third mounting plate (301) is connected to the output end of the first rotating motor (204), and the second side plate is used to mount the third linear motor (302); the counterweight (6) is mounted on an end of the first side plate away from the second side plate.

8. The multi-degree-of-freedom robot according to claim 5, characterized in that: The instrument rotary motor (406) is a hollow motor; the actuator mechanism also includes an instrument linear motor (407) mounted on the end motor seat (405) and a push rod (408) mounted on the output end of the instrument linear motor (407); the push rod (408) passes through the end motor seat (405) and the hollow motor and extends into the actuator (404) and is used to push the actuator (404) to open and close; the instrument rotary motor (406) is connected to the actuator (404) through the instrument mounting seat; the actuator (404) is detachably connected to the instrument mounting seat (409).

9. The multi-degree-of-freedom robot according to claim 5, characterized in that: The rotation axes of the first linear motor (102), the second linear motor (202) and the first rotary motor (204) are orthogonal to each other; the movement axis of the third linear motor (302) is parallel to the rotation axis of the first rotary motor (204); the movement axes of the third linear motor (302) and the fourth linear motor (402) are orthogonal to the rotation axis of the second rotary motor (304); the rotation axes of the first rotary motor (204), the second rotary motor (304) and the instrument rotary motor (406) intersect at a point and the point is located on the axis of the execution instrument.

10. A robot control method, characterized in that: The method for realizing the control of the multi-degree-of-freedom robot according to claim 9 comprises: Obtaining a position L1 of the first linear motor, a position L2 of the second linear motor, a position L3 of the third linear motor, a position L4 of the fourth linear motor, an angle θ1 of the first rotary motor, and an angle θ2 of the second rotary motor; Define a virtual wrist joint point β, and obtain the distance between the virtual wrist joint point β and the control transfer point O; Based on the distance of the virtual wrist joint point β from the control transfer point O, the motions of the first linear motor, the second linear motor, the third linear motor, the fourth linear motor, the first rotary motor, and the second rotary motor are combined into at least one linear motion generator and at least one rotary motion generator; The desired command is input into the linear motion generator and the rotary motion generator, and the motion outputs of the first linear motor, the second linear motor, the third linear motor, the fourth linear motor, the first rotary motor and the second rotary motor are obtained by accumulating the outputs.

11. A robot control method according to claim 10, characterized in that: The distance between the virtual wrist joint point β and the control transfer point O is specifically: Δ=β+L4 The linear motion generator is specifically: The rotational motion generators are provided with three, namely a first virtual rotation generator, a second virtual rotation generator and a rotation generator; The first virtual rotation generator is specifically: The second virtual rotation generator is specifically: The rotation generator is specifically: Wherein, k1 is a parameter factor ranging from 0 to 1; Δ is the distance between the virtual wrist joint point β and the control transfer point O; L4 is the current position of the fourth linear motor; θ1 and θ2 are the current angles of the first and second rotary motors; and Respectively represent the operating speeds of the first linear motor, the second linear motor, the third linear motor and the fourth linear motor for executing the linear motion generator; and The first linear motor and the second linear motor are used to execute the operation speed of the first virtual rotation generator; and The operating speed of the third linear motor and the fourth linear motor for executing the second virtual rotation generator; x, y, x are the positions of the actuator on the coordinate axis; is the linear displacement speed of the actuator in the desired instruction; a and b are the rotation angles of the actuator; is the rotation speed of the execution device in the expected instruction; is the rotation speed of the first rotating motor; is the rotation speed of the second rotating motor; The rotation speed of the instrument's rotation motor.

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