CN113977631A

CN113977631A - Mechanical arm

Info

Publication number: CN113977631A
Application number: CN202111519640.XA
Authority: CN
Inventors: 王挺; 黄浩东; 王元军
Original assignee: Ningbo Ruida Medical Instrument Co ltd
Current assignee: Ningbo Ruida Medical Instrument Co ltd
Priority date: 2021-12-13
Filing date: 2021-12-13
Publication date: 2022-01-28

Abstract

Embodiments of the present description provide a robot arm, including a robot arm body and a gravity balance assembly; the mechanical arm body comprises a support and a connecting rod assembly; the support and the connecting rod assembly are rotationally connected through a first rotating shaft; the gravity balance assembly comprises a spring and a balance rope, one end of the spring is connected with the support, the other end of the spring is connected with one end of the balance rope, and the other end of the balance rope is connected to the connecting rod assembly; the elastic force of the spring can act on the connecting rod assembly through the balancing rope to at least partially balance the gravity moment generated by the gravity of the connecting rod assembly relative to the first rotating shaft. The mechanical arm provided by the embodiment of the specification can realize gravity balance at any posture and any time in the motion space, and has the advantages of simple and compact structure, light weight, convenience in installation and capability of running safely and reliably.

Description

Mechanical arm

Technical Field

The specification relates to the field of mechanical arms, in particular to a mechanical arm.

Background

The mechanical arm is widely applied to the fields of industry, medical treatment and the like as a novel man-machine interaction way. For example, robotic arms of a parallel linkage design are commonly used in surgical robots (e.g., single-bore surgical robots or multi-bore surgical robots). However, in use of a robotic arm, the weight of the robotic arm typically negatively impacts the motion of the robotic arm (e.g., motion accuracy, dexterity, safety, reliability, etc.) and force feedback to the operator. Therefore, in the design and use of the mechanical arm, the problem of balancing the gravity of the mechanical arm needs to be considered, so as to eliminate the negative influence caused by the gravity of the mechanical arm. At present, the gravity of the mechanical arm can be balanced by adopting modes such as motor compensation, counterweight design or air cylinders. However, the motor compensation mode can cause the problem of overlarge motor load, and potential safety hazards exist. The counterweight design or the air cylinder mode can cause the problem that the mechanical arm is too heavy.

Therefore, how to reasonably design the gravity balance mode of the mechanical arm is a problem which needs to be solved urgently at present.

Disclosure of Invention

An embodiment of the present specification provides a robot arm, including: the mechanical arm comprises a mechanical arm body and a gravity balance assembly; the mechanical arm body comprises a support and a connecting rod assembly; the support and the connecting rod assembly are rotationally connected through a first rotating shaft; the gravity balance assembly comprises a spring and a balance rope, one end of the spring is connected with the support, the other end of the spring is connected with one end of the balance rope, and the other end of the balance rope is connected to the connecting rod assembly; the elastic force of the spring can act on the connecting rod assembly through the balancing rope to at least partially balance the gravity moment generated by the gravity of the connecting rod assembly relative to the first rotating shaft.

In some embodiments, the linkage assembly includes a first linkage and a second linkage; the support and the first connecting rod are rotatably connected through the first rotating shaft, and the first connecting rod and the second connecting rod are rotatably connected through the second rotating shaft; the support, the first connecting rod and the second connecting rod form a parallel linkage mechanism; the other end of the balance rope is fixedly connected to the first connecting rod.

In some embodiments, a connection mechanism is disposed on the first link, and the connection mechanism is fixedly connected to the other end of the balance rope.

In some embodiments, the gravity balance assembly further comprises a pulley arranged on the support, and the other end of the balance rope is fixedly connected with the connecting mechanism after the balance rope is wound on the pulley; a distance between the connection mechanism and the first rotation shaft is the same as a distance between the pulley and the first rotation shaft, and a deformation amount of the spring is the same as a distance between the pulley and the connection mechanism.

In some embodiments, the spring rate of the spring and the distance between the connection mechanism and the first rotating shaft satisfy the following relationship:

wherein K is the spring rate of the spring, G₁Is the gravity of the first link, L₁Length of the first link, G₂Is the gravity of the second link, L₂Is the distance between the connecting mechanism and the first rotating shaft.

In some embodiments, the first link is provided with a position adjustment structure for adjusting a position of the link mechanism in a length direction of the first link.

In some embodiments, the one end of the balance rope is provided with a balance rope tensioning device, the other end of the spring is provided with a connecting seat, and the balance rope is connected with the connecting seat through the balance rope tensioning device so as to be connected with the other end of the spring; when the connecting rod assembly rotates around the first rotating shaft relative to the support, the connecting seat can move along the length direction of the support under the action of the balance rope and the spring.

In some embodiments, a sliding block is arranged on the connecting seat, and a guide rail matched with the sliding block is arranged on the support.

In some embodiments, the robot arm further includes a torque sensor disposed on the first rotating shaft for detecting a rotating torque applied to the first rotating shaft.

In some embodiments, the robotic arm further comprises a servo motor electrically connected to the torque sensor and drivingly connected to the first rotational axis; when the torque sensor detects the rotation torque applied to the first rotation shaft, the servo motor can output a corresponding compensation torque to the first rotation shaft based on the rotation torque so as to balance the rotation torque.

Drawings

The present description will be further explained by way of exemplary embodiments, which will be described in detail by way of the accompanying drawings. These embodiments are not intended to be limiting, and in these embodiments like numerals are used to indicate like structures, wherein:

FIG. 1 is a schematic diagram of the overall construction of a robotic arm according to some embodiments herein;

FIG. 2 is a schematic diagram of a backside structure of a robotic arm according to some embodiments herein;

FIG. 3 is a schematic cross-sectional view X-X of FIG. 2;

FIG. 4 is a schematic view of the back side of the robotic arm shown in FIG. 2, partially cut away;

FIG. 5 is a force-receiving schematic view of the linkage assembly shown in FIG. 2 rotated at an angle relative to the mount about the axis of the first pivot axis;

FIG. 6 is a block diagram of a control system implementing balancing of turning moments, according to some embodiments herein;

FIG. 7 is a schematic diagram of a portion of a robotic arm according to some embodiments of the present description;

fig. 8 is a partially enlarged view of the region P shown in fig. 7.

Detailed Description

In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings used in the description of the embodiments will be briefly described below. It is obvious that the drawings in the following description are only examples or embodiments of the present description, and that for a person skilled in the art, the present description can also be applied to other similar scenarios on the basis of these drawings without inventive effort. Unless otherwise apparent from the context, or otherwise indicated, like reference numbers in the figures refer to the same structure or operation.

As used in this specification and the appended claims, the terms "a," "an," "the," and/or "the" are not intended to be inclusive in the singular, but rather are intended to be inclusive in the plural, unless the context clearly dictates otherwise. In general, the terms "comprises" and "comprising" merely indicate that steps and elements are included which are explicitly identified, that the steps and elements do not form an exclusive list, and that a method or apparatus may include other steps or elements.

The mechanical arm is an important component in a robot system such as an industrial robot and a surgical robot, and can be used for industrial production, surgical treatment and the like. For example, a surgical robot often uses a robot arm designed as a parallel linkage mechanism, and when performing surgical treatment, a doctor can control a distal end effector of the surgical robot to perform actions such as cutting, knotting, and suturing by operating the robot arm.

In the design and use of the mechanical arm, the gravity balance problem of the mechanical arm generally needs to be considered, so that the flexibility, safety or reliability of the movement of the mechanical arm and the force feedback accuracy of an operator are ensured, and the operation of the operator on the mechanical arm is labor-saving and the like. The gravity balance of the mechanical arm can be understood as that the mechanical arm can be in any posture in a motion space of the mechanical arm, for example, when a motion member (for example, a connecting rod) in the mechanical arm rotates to a certain position and the driving force applied to the motion member disappears, the gravity of the motion member can be balanced, so that the motion member can not rotate again due to the gravity of the motion member, the motion member can be kept at the current position, and the mechanical arm can be kept in the corresponding posture after the driving force for driving the motion of the mechanical arm disappears. Specifically, gravity balance can be achieved by balancing a gravity moment generated by the gravity of the link in the mechanical arm relative to a rotating joint (e.g., a rotating shaft) of the link, and balancing the gravity moment generated by the gravity of the link in the mechanical arm relative to the rotating shaft can be achieved by offsetting the gravity moment by a moment which is generated relative to the same rotating shaft and has the same magnitude and the opposite direction with respect to the gravity moment.

Embodiments of the present disclosure provide a robot arm, in which a spring generates an elastic force in a deformed state (e.g., an extended state or a compressed state), and then the elastic force acts on a moving member (e.g., a link) of the robot arm through a balancing rope to at least partially balance a gravity moment to be balanced in the robot arm, that is, the elastic force may act on the moving member of the robot arm through the balancing rope to generate a balancing moment with respect to a rotation axis thereof, and the balancing moment may balance part or all of a gravity moment generated by the gravity of the moving member of the robot arm with respect to the rotation axis thereof, thereby achieving gravity balancing of the robot arm. When the gravity distance to be balanced changes along with the change of the rotation angle of the relevant motion member (for example, a connecting rod) of the mechanical arm, the balance torque also changes along with the change of the rotation angle of the relevant motion member of the mechanical arm, so that the mechanical arm can realize gravity balance when the relevant motion member rotates at any angle, the operation of the mechanical arm is safe and reliable, the motion is flexible, the force feedback to an operator is accurate, and the mechanical arm is labor-saving and convenient to operate manually by the operator. In addition, the mechanical arm provided by the embodiment of the specification realizes gravity balance by enabling the spring to be in a deformed state, has a simple and compact structure and lighter weight, does not influence the operation precision and the operation comfort of the mechanical arm due to excessive inertia force, and does not interfere the movement of the mechanical arm.

The mechanical arm provided by the embodiment of the present disclosure and the principle of gravity balance thereof will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of the overall structure of a robotic arm according to some embodiments herein. FIG. 2 is a schematic diagram of a backside structure of a robotic arm according to some embodiments herein; FIG. 3 is a schematic cross-sectional view X-X of FIG. 2; fig. 4 is a schematic view of the back side of the robot arm shown in fig. 2, partially cut away.

As shown in fig. 1, 2, 3, and 4, the robot arm 100 includes a robot arm body 10 and a gravity balance assembly 20. The robot arm body 10 may include a support 11 and a link assembly 12, and the support 11 and the link assembly 12 may be rotatably connected by a first rotating shaft 13 such that the link assembly 12 may rotate relative to the support 11 about an axial direction of the first rotating shaft 13. The gravity balance assembly 20 may include a spring 21 and a balance rope 22 (e.g., a wire rope), one end of the spring 21 being connected to the support 11, the other end of the spring 21 being connected to one end of the balance rope 22, and the other end of the balance rope 22 being connected to the link assembly 12. The spring force of the spring 21 can act on the linkage assembly 12 via the balancing cord 22 to at least partially balance the gravitational moment of the linkage assembly 12 generated by the gravitational force relative to the first rotational axis 13.

In some embodiments, when the link assembly 12 rotates relative to the support 11 by a certain angle around the axial direction of the first rotating shaft 13, the link assembly 12 can bring the spring 21 into a deformed state (e.g., an extended state or a compressed state) by the balancing string 22, and the elastic force of the spring 21 in the deformed state can react to the link assembly 12 by the balancing string 22, so that the elastic force can generate a balancing moment relative to the first rotating shaft 13, which can at least partially balance the gravity moment generated by the gravity of the link assembly 12 relative to the first rotating shaft 13. In some embodiments, the balancing moment may be opposite to a gravity moment generated by the gravity of the connecting rod assembly 12 relative to the first rotating shaft 13, and the balancing moment is greater than or equal to the gravity moment generated by the gravity of the connecting rod assembly 12 relative to the first rotating shaft 13, so as to balance (or cancel) the gravity moment generated by the gravity of the connecting rod assembly 12 relative to the first rotating shaft 13. In some embodiments, the balancing moment may be opposite to a gravity moment generated by the gravity of the connecting rod assembly 12 relative to the first rotation axis 13, and the balancing moment is smaller than the gravity moment generated by the gravity of the connecting rod assembly 12 relative to the first rotation axis 13 to balance (or offset) a portion of the gravity moment generated by the gravity of the connecting rod assembly 12 relative to the first rotation axis 13. In some embodiments, when the balancing moment is greater than or less than the gravity moment generated by the gravity of the link assembly 12 relative to the first rotating shaft 13, a rotating moment (i.e., a difference between the balancing moment and the gravity moment generated by the gravity of the link assembly 12 relative to the first rotating shaft 13) is also present on the first rotating shaft 13, and the rotating moment can be balanced by adjusting the magnitude of the balancing moment or by motor compensation. A description of how to balance the turning moment on the first turning axis 13 when the balancing moment is greater or less than the gravitational moment created by the gravitational force of the connecting-rod assembly 12 relative to the first turning axis 13 may be found elsewhere in this specification (e.g., fig. 5 and its associated description).

In some embodiments, the robotic arm 100 may be a parallel linkage robotic arm. Specifically, as shown in conjunction with fig. 1, 2, 3, and 4, the linkage assembly 12 may include a first link 121 and a second link 122. The holder 11 and the first link 121 may be rotatably connected by a first rotating shaft 13, and the first link 121 and the second link 122 may be connected by a second rotating shaft 123 such that the first link 121 and the second link 122 may rotate with respect to the holder 11 about an axial direction of the first rotating shaft 13, and the second link 122 may rotate with respect to the first link 121 about an axial direction of the second rotating shaft 123. The support 11, the first link 121 and the second link 122 may form a parallel linkage mechanism, so that the second link 122 may be always parallel to the support 11 during the rotation of the link assembly 12 around the first rotation axis 13. For example only, the parallel linkage formed by the support 11, the first link 121 and the second link 122 may be formed by controlling the first rotating shaft 13 and the second rotating shaft 123 to rotate synchronously by the same angle in a belt transmission or chain transmission manner, that is, when the first link 121 rotates by a certain angle relative to the support 11 around the axial direction of the first rotating shaft 13, the second link 122 rotates by the same angle relative to the first link 121 around the second rotating shaft 123. By this arrangement, the gravity distance required for the robot arm 100 to be balanced may include the gravity distance generated by the gravity of the first link 121 and the second link 122 with respect to the first rotation axis 13.

In some embodiments, referring to fig. 1, 3 or 4, the other end of the balancing cord 22 may be fixedly connected to the first link 121. In some embodiments, the first link 121 may be provided with a connection mechanism 1211, and the connection mechanism 1211 may be fixedly connected to the other end of the balance cord 22. It should be noted that the specific structure of the connection mechanism 1211 is not limited in the embodiments of the present specification, and the connection mechanism 1211 may be any mechanism capable of realizing a fixed connection with the other end of the balance cord 22. For example, the connection mechanism 1211 may be a boss (or a boss) provided on the first link 121, and the other end of the balance cord 22 may be tied to the boss to achieve a fixed connection. For another example, the other end of the balance cord 22 may be provided with a connector, and the connector may be fixedly connected to the connecting mechanism 1211 or directly connected to the first link 121 by clamping, gluing, or welding.

In some embodiments, referring to fig. 3 and 4, the gravity balance assembly 20 may further include a pulley 23 disposed on the support 11, and the balance rope 22 is wound around the pulley 23 and is fixedly connected to the connecting mechanism 1211 at the other end thereof. Here, the distance between the connection mechanism 1211 and the first rotation shaft 13 is the same, and the amount of deformation of the spring 21 is the same as the distance between the pulley 23 and the connection mechanism 1211 (or the length of the balance cord 22 between the connection mechanism 1211 and the first rotation shaft 13). That is, during the rotation of the link assembly 12 relative to the support 11 about the axial direction of the first rotating shaft 13, the included angle between the support 11 and the first link 121 is changed, so that the distance between the pulley 23 and the connecting mechanism 1211 is also changed, and the deformation amount of the link assembly 12 (the first link 121) when the spring 21 is in the deformed state by the balance rope 22 is always the same as the distance between the pulley 23 and the connecting mechanism 1211.

By making the amount of deformation of the spring 21 the same as the distance between the pulley 23 and the connection mechanism 1211, the linear relationship of the elastic force generated by the spring 21 and the amount of deformation can be converted into a trigonometric function relationship (for example, a sinusoidal relationship) of the elastic force and the angle by which the first link 121 rotates about the axial direction of the first rotating shaft 13 with respect to the holder 11, so that the elastic force can be varied in a trigonometric function of the angle by which the first link 121 is rotated about the axial direction of the first rotating shaft 13 with respect to the holder 11, so that the balance moment generated by the elastic force with respect to the first rotation axis 13 is changed in accordance with a trigonometric function of the angle of rotation of the first link 121 with respect to the mount 11 in the axial direction of the first rotation axis 13, the moment that the robot arm 100 needs to balance (i.e., the gravity moment generated by the gravity of the link assembly 12 relative to the first rotating shaft 13) also varies according to the trigonometric function of the angle by which the axial direction of the first rotating shaft 13 of the first link 121 rotates relative to the support 11. Further, when the connecting rod assembly 12 rotates at any angle, the balance moment generated by the elastic force relative to the first rotating shaft 13 can balance the gravity moment (or part of the gravity moment) generated by the connecting rod assembly 12 relative to the first rotating shaft 13.

In some embodiments, as shown in fig. 2, 3 and 4, one end of the balance cord 22 may be provided with a balance cord tensioning device 221, and the other end of the spring 21 is provided with a connection seat 211. One end of the balance cord 22 may be connected to the connection seat 211 through a balance cord tensioning device 221 (e.g., a tensioning wheel), thereby achieving connection to the other end of the spring 21. The balance rope tension device 221 can keep the balance rope 22 in a tension state all the time, so as to ensure that the elastic force of the spring 21 can fully act on the connecting rod assembly 12 through the balance rope 22. When the link assembly 12 rotates relative to the support 11 about the axial direction of the first rotating shaft 13, the connecting seat 211 can move in the length direction of the support 11 under the action of the balance rope 22 and the spring 21, so that the deformation amount of the spring 21 is changed. For example, in fig. 4, when the first link 121 rotates in the counterclockwise direction with respect to the support 11, the balance cord 22 pulls the connection seat 211 upward in the length direction of the support 11 by the first link 121, so that the spring 21 is in a compressed state, and when the first link 121 rotates in the clockwise direction with respect to the support 11, the spring 21 is restored to be deformed by the elastic force to drive the connection seat 211 downward in the length direction of the support 11, and in this process, the compression amount of the spring 21 is always the same as the distance between the pulley 23 and the connection 1211.

In some embodiments, referring to fig. 2 or fig. 4, the connecting seat 211 may be provided with a sliding block 2111, and the support 11 may be provided with a guide rail 111 adapted to the sliding block 2111. When the connecting seat 211 can move along the length direction of the support 11 under the action of the balance rope 22 and the spring 21, the slider 2111 moves on the guide rail 111, so that the movement of the connecting seat 211 is relatively smooth and does not collide with the support 11, and the rotation of the connecting component 12 is safer and more reliable.

In some embodiments, referring to fig. 2, 3 or 4, the gravity balance assembly 20 may further include a guide wheel 24 disposed on the support 11, and the other end of the balance rope 22 is wound around the guide wheel 24 and the pulley 23, and then is fixedly connected to the connection mechanism 1211. The elastic force generated by the spring 21 may be generated by the extension or compression of the spring 21, and the description of the present specification will be mainly given by the elastic force generated by the compression of the spring 21. In some embodiments, the manner in which the spring force of the spring 21 is generated may be set according to the type of the spring 21 and/or the position of the guide wheel 24. For example, when the spring 21 is a compression spring, the guide pulley 24 may be disposed above one end (an end connected to the support 11) of the spring 21, and when the first link 121 rotates about the axial direction of the first rotating shaft 13 with respect to the support 11, the spring 21 is in a compressed state by the balance cord 22 to generate an elastic force. For another example, when the spring 21 is an extension spring, the guide pulley 24 may be disposed below the other end of the spring 21 (the end connected to the one end of the balance cord 22), and when the first link 121 rotates relative to the holder 11 in the axial direction of the first rotating shaft 13, the spring 21 is extended by the balance cord 22 to generate an elastic force.

How the gravity balance assembly 20 generates the balancing moment to balance the gravity of the linkage assembly 12 with respect to the gravity moment generated by the first rotating shaft 13 in the robot arm 100 will be described in detail with reference to fig. 4.

Fig. 5 is a force-receiving schematic view of the link assembly shown in fig. 2 rotated at a certain angle relative to the mount about the axial direction of the first rotating shaft.

As shown in fig. 5, the angle of rotation of the link assembly 12 (first link 121) relative to the mount 11 about the axial direction of the first rotating shaft 13 is set to θ; the gravity of the first link 121 and the second link 122 is G₁And G₂(ii) a The first link 121 has a length L₁(ii) a The distance between the connection mechanism 1211 and the first rotation shaft 13 and the distance between the pulley 23 and the first rotation shaft are L₂(ii) a The gravity distances of the first link 121 and the second link 122 with respect to the first rotation axis 13 are T₁And T₂(ii) a A. B, C represent the positions of the first rotating shaft 13, the connecting mechanism 1211, and the pulley 23, respectively. In the embodiment of the present specification, the connecting means 1211The position may be used to indicate the connection point of the other end of the balance cord 22 to the first link 121.

The gravity distance T that the robot arm 100 needs to balance is:

T＝T₁+T₂ (1)

calculated to obtain T₁And T₂Respectively as follows:

T₂＝G₂×L₁×sinθ； (3)

further, it can be found that:

setting the elastic force generated by the spring 21 as F; the spring 21 has a spring rate of K; the amount of deformation of the spring 21 is Δ_x(ii) a The spring 21 generates a spring force F having a moment arm L relative to the first rotation axis 13₃(ii) a The distance between the pulley 23 and the connecting mechanism 1211 is L₄。

Further, the balance moment T' generated by the elastic force of the spring 21 on the first rotating shaft 13 is:

T′＝F×L₃＝K×Δ_x×L₃ (5)

since the distance between the connection 1211 and the first rotation shaft 13 is the same as the distance between the pulley 23 and the first rotation shaft 13, and the amount of deformation of the spring 21 and the distance between the pulley 23 and the connection 1211 are L₄So that the connecting line between the position a of the first rotating shaft 13, the position B of the connecting mechanism 1211 and the position C of the pulley 23 may form an isosceles triangle Δ_ABCThe lengths of three sides of the isosceles triangle are L respectively₂、L₂、L₄(ii) a Wherein, Delta_x＝L₄；

In isosceles triangle delta_ABCHas the following relationship:

L₄ ²＝L₂ ²+L₂ ²-2×L₂×L₂×cosθ (6)

thus, the distance L between the pulley 23 and the connection 1211₄Comprises the following steps:

the gravity distance T of the robot arm 100 to be balanced can be balanced by the balance moment T' generated on the first rotating shaft 13 by the elastic force of the spring 21; t 'and T need to be opposite in direction and equal in size, i.e., T' is T, so that the gravity balance of the robot arm 100 can be achieved. Further, it can be found that:

as can be seen from equation (10), when designing the robot arm 100, G is₁、L₁、G₂In the case where it has been determined that an appropriate spring can be selected as the spring 21 according to the formula (10). Specifically, the spring rate K of the spring 21 and the distance between the connection mechanism 1211 and the first rotating shaft 13 may satisfy the following relationship:

therefore, an appropriate spring rate can be selected for the spring 21 according to equation (11) so that the elastic force of the spring 21 can balance the gravity distance T that the robot arm 100 needs to balance with respect to the balancing moment T' generated by the first rotating shaft 13.

In some embodiments, at G₁、L₁、G₂If K is determined, the distance L between the connection mechanism 1211 and the first rotating shaft 13 may be appropriately set according to equation (11)₂So that the elastic force of the spring 21 can balance the gravity distance T that the robot arm 100 needs to balance with respect to the balancing moment T' generated by the first rotating shaft 13.

In some embodiments, a distance L between the connection 1211 and the first rotation axis 13 is provided₂This can be achieved by adjusting the position of the connection mechanism 1211 in the longitudinal direction of the first link 121 (i.e., position B).

In some embodiments, the linkage assembly 12 may include only one link (e.g., the first link 121). When the link assembly 12 includes only the first link 121, the spring rate K of the spring 21 and the distance between the connection mechanism 1211 and the first rotation axis 13 may satisfy the following relationship:

in some cases, due to inaccuracy of the spring force and the fact that the influence of external forces such as friction on the gravity balance of the robot arm 100 is not considered in the design of the robot arm 100, the gravity balance assembly 20 may be designed such that the spring rate of the spring 21 and/or the position of the connection mechanism 1211 in the length direction of the first link 121, which are theoretically calculated (for example, calculated according to equation (11)), of the robot arm 100, generate a balance torque that deviates from the gravity distance at which the robot arm 100 needs to be balanced, that is, T '> T or T' < T, and therefore, a rotation torque is applied to the first rotation shaft 13 when the driving torque (the torque that drives the first rotation shaft 13 to normally rotate) on the first rotation shaft 13 disappears, and the gravity balance of the robot arm 100 cannot be achieved.

In some embodiments, in order to better achieve the gravity balance of the robot arm 100 under the above conditions, the robot arm 100 may further include a torque sensor (not shown in the figure), which may be disposed on the first rotating shaft 13, for detecting the rotating torque applied to the first rotating shaft 13. The rotation moment may include a balance moment generated by the elastic force of the spring 21 with respect to the first rotation axis 13, a gravity distance generated by the gravity of the link assembly 12 with respect to the first rotation axis 13, or a difference therebetween. By providing the torque sensor at the first rotating shaft 13, it is possible to monitor whether the robot arm 100 achieves the gravity balance in real time. When the torque sensor detects that the first rotating shaft 13 is still subjected to a rotating torque (for example, the rotating torque may include a difference between a balancing torque generated by the elastic force of the spring 21 with respect to the first rotating shaft 13 and a gravity torque generated by the gravity of the link assembly 12 with respect to the first rotating shaft 13), the gravity balance of the robot arm 100 may be achieved by adjusting the magnitude of the balancing torque or balancing the rotating torque based on the rotating torque.

In some embodiments, the gravity balance of the robot arm 100 may be achieved by the servo motor outputting additional torque to balance the rotational torque. In some embodiments, the robot arm 100 may further include a servo motor, the servo motor may be electrically connected to the torque sensor and in transmission connection with the first rotating shaft 13, and when the torque sensor detects a rotating torque applied to the first rotating shaft 13, the servo motor may output a corresponding compensation torque to the first rotating shaft 13 based on the rotating torque to balance the rotating torque.

Further, FIG. 6 is a block diagram of a control system implementing balancing of turning moments, according to some embodiments described herein. As shown in fig. 6, the control system 200 for balancing the rotation torque by outputting the additional torque through the servo motor may include a servo motor 210, a torque sensor 220, and a torque controller 230, wherein the servo motor 210 may be electrically connected to the torque sensor 220 through the torque controller 230, when the torque sensor 220 detects the rotation torque applied to the first rotation axis 13 (for example, the rotation torque may include a difference between a balancing torque T' generated by an elastic force of the spring 21 with respect to the first rotation axis 13 and a gravity distance T generated by a gravity of the link assembly 12 with respect to the first rotation axis 13), the rotation torque may be transmitted to the torque controller 230, and the torque controller 230 may control the servo motor 210 to output a compensation torque corresponding to the rotation torque based on the rotation torque to balance the rotation torque. In some embodiments, when T' > T, the compensation torque output by the servo motor is in the same direction as the gravity of the link assembly 12 with respect to the first rotation axis 13 from the T. In some embodiments, when T' < T, the compensation torque output by the servo motor is opposite to the direction of the gravitational distance T generated by the gravitational force of the linkage assembly 12 with respect to the first rotation axis 13. Wherein the magnitude of the compensating moment is the same as the difference between the balancing moment T' generated by the elastic force of the spring 21 with respect to the first rotation axis 13 and the gravitational distance T generated by the gravitational force of the link assembly 12 with respect to the first rotation axis 13.

In some embodiments, the gravity balance of the robotic arm 100 may also be achieved by adjusting the magnitude of the balancing moment. In some embodiments, as can be seen from equation (9), the balancing moment is related to the distance between the connection 1211 and the first rotating shaft 13. Therefore, the magnitude of the balancing moment can be adjusted by adjusting the distance between the connection mechanism 1211 and the first rotating shaft 13. In some embodiments, the distance between the connection mechanism 1211 and the first rotating shaft 13 may be adjusted by adjusting the position of the connection mechanism 1211 in the length direction of the first link 121, thereby achieving the adjustment of the balancing moment.

In some embodiments, in order to facilitate adjusting the position of the connection mechanism 1211 in the length direction of the first link 121, a position adjustment mechanism may be provided on the first link 121, and the position adjustment mechanism may be used to adjust the position of the connection mechanism 1211 in the length direction of the first link 121.

Further, FIG. 7 is a schematic diagram of a portion of a robotic arm according to some embodiments of the present disclosure. Fig. 8 is a partially enlarged view of the region P shown in fig. 7.

As shown in fig. 7 and 8, the first link 121 is provided with a position adjustment mechanism 124, and the position adjustment mechanism 124 may include a movable slot 1241 opened on the first link 121 and a bolt 1242 rotatably installed in the movable slot. The connecting mechanism 1211 is provided with a threaded through hole adapted to the bolt 1242, so as to be in threaded connection with the bolt 1242. By rotating the bolt 1242, the connection mechanism 1211 can move in the movable slot 1241 along the length direction of the first link 121, so that the position of the connection mechanism 1211 in the length direction of the first link 121 can be adjusted to adjust the counter moment. In some embodiments, the adjusted balancing moment is the same size as the gravity moment generated by the gravity of the linkage assembly 12 relative to the first rotation axis 13 to achieve the gravity balance of the robot arm 100. For details of how the position adjusting mechanism 1242 adjusts the position of the connecting mechanism 1211, reference may be made to the transmission manner of the lead screw nut, which is not described herein again.

In some embodiments, the operator may adjust the position of the connection mechanism 1211 in the length direction of the first link 121 to adjust the distance between the connection mechanism 1211 and the first rotation shaft 13 based on the detection result (for example, the magnitude and direction of the rotation moment) of the moment sensor, the adjustment of the balance torque can be achieved by repeatedly adjusting the position of the connection mechanism 1211 in the longitudinal direction of the first link 121 based on its own judgment (for example, whether the first rotary shaft 13 is still rotating after the driving torque disappears and the direction of rotation of the first rotary shaft), so as to adjust the distance between the connection mechanism 1211 and the first rotary shaft 13, thereby adjusting the magnitude of the balancing moment to be closer to or the same as the gravitational force of the connecting-rod assembly 12 with respect to the first axis of rotation 13, to maximally or fully balance the gravitational moment generated by the weight of the connecting-rod assembly 12 with respect to the first axis of rotation 13. For example only, when the torque sensor detects that the balancing torque is smaller than the gravity torque generated by the weight of the link assembly 12 with respect to the first rotating shaft 13, or the operator observes that the first rotating shaft 13 is also rotating in the direction of the gravity torque in the case where the driving torque disappears, the balancing torque is proportional to the distance between the connecting mechanism 1211 and the first rotating shaft 13, as can be obtained from equation (9). Therefore, the operator can increase the distance between the connection mechanism 1211 and the first rotation axis 13 by adjusting the position of the connection mechanism 1211 in a direction away from the first rotation axis 13 along the length direction of the first link 121, thereby increasing the balancing moment.

The beneficial effects that may be brought by the embodiments of the present description include, but are not limited to: (1) the mechanical arm provided by the embodiment of the specification generates the balance torque relative to the corresponding rotating shaft through the elastic force of the spring so as to balance the gravity distance required by the mechanical arm, so that the gravity balance of the mechanical arm is realized, the structure is simple and compact, the weight is light, the installation is convenient, the operation safety and reliability of the mechanical arm and the motion flexibility can be ensured, the force feedback to an operator can not be influenced, and the operation of the mechanical arm by the operator is more labor-saving and convenient; (2) when the connecting rod assembly rotates at any angle relative to the support, the elastic force of the spring can balance the gravity moment generated by the connecting rod assembly relative to the first rotating shaft relative to the balance moment generated by the first rotating shaft, so that the gravity balance of the mechanical arm can be realized at any posture (or any time) of the motion space of the mechanical arm; (3) when a difference exists between a balance moment generated by the elastic force of the spring relative to the first rotating shaft and a gravity moment generated by the connecting rod assembly relative to the first rotating shaft, the moment sensor and the servo motor are arranged, the moment sensor can detect the rotating moment applied to the first rotating shaft, and the servo motor can output a compensation moment to the first rotating shaft based on the rotating moment so as to balance the rotating moment and achieve the purpose of gravity balance of the mechanical arm; (4) when a difference exists between a balance moment generated by the elastic force of the spring relative to the first rotating shaft and a gravity moment generated by the connecting rod assembly relative to the first rotating shaft, the position of the connecting mechanism on the first connecting rod is adjusted by arranging the position adjusting mechanism, so that the balance moment generated by the elastic force of the spring relative to the first rotating shaft is adjusted, and the gravity balance of the mechanical arm is better realized.

It is to be noted that different embodiments may produce different advantages, and in different embodiments, any one or combination of the above advantages may be produced, or any other advantages may be obtained.

Having thus described the basic concept, it will be apparent to those skilled in the art that the foregoing detailed disclosure is to be regarded as illustrative only and not as limiting the present specification. Various modifications, improvements and adaptations to the present description may occur to those skilled in the art, although not explicitly described herein. Such modifications, improvements and adaptations are proposed in the present specification and thus fall within the spirit and scope of the exemplary embodiments of the present specification.

Also, the description uses specific words to describe embodiments of the description. Reference throughout this specification to "one embodiment," "an embodiment," and/or "some embodiments" means that a particular feature, structure, or characteristic described in connection with at least one embodiment of the specification is included. Therefore, it is emphasized and should be appreciated that two or more references to "an embodiment" or "one embodiment" or "an alternative embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, some features, structures, or characteristics of one or more embodiments of the specification may be combined as appropriate.

Similarly, it should be noted that in the preceding description of embodiments of the present specification, various features are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure aiding in the understanding of one or more of the embodiments. This method of disclosure, however, is not intended to imply that more features than are expressly recited in a claim. Indeed, the embodiments may be characterized as having less than all of the features of a single embodiment disclosed above.

Finally, it should be understood that the embodiments described herein are merely illustrative of the principles of the embodiments of the present disclosure. Other variations are also possible within the scope of the present description. Thus, by way of example, and not limitation, alternative configurations of the embodiments of the specification can be considered consistent with the teachings of the specification. Accordingly, the embodiments of the present description are not limited to only those embodiments explicitly described and depicted herein.

Claims

1. A robot arm, comprising: the mechanical arm comprises a mechanical arm body and a gravity balance assembly;

the mechanical arm body comprises a support and a connecting rod assembly; the support and the connecting rod assembly are rotationally connected through a first rotating shaft;

the gravity balance assembly comprises a spring and a balance rope, one end of the spring is connected with the support, the other end of the spring is connected with one end of the balance rope, and the other end of the balance rope is connected to the connecting rod assembly;

the elastic force of the spring can act on the connecting rod assembly through the balancing rope to at least partially balance the gravity moment generated by the gravity of the connecting rod assembly relative to the first rotating shaft.

2. A robotic arm as claimed in claim 1, in which the linkage assembly comprises a first link and a second link; the support and the first connecting rod are rotatably connected through the first rotating shaft, and the first connecting rod and the second connecting rod are rotatably connected through the second rotating shaft; the support, the first connecting rod and the second connecting rod form a parallel linkage mechanism; the other end of the balance rope is fixedly connected to the first connecting rod.

3. A robotic arm as claimed in claim 2, in which the first link is provided with a connecting mechanism which is fixedly connected to the other end of the balancing line.

4. The mechanical arm as claimed in claim 3, wherein the gravity balance assembly further comprises a pulley arranged on the support, and the balance rope is wound around the pulley and then fixedly connected with the connecting mechanism at the other end; a distance between the connection mechanism and the first rotation shaft is the same as a distance between the pulley and the first rotation shaft, and a deformation amount of the spring is the same as a distance between the pulley and the connection mechanism.

5. A robotic arm as claimed in claim 4, in which the spring rate of the spring isThe number and the distance between the connecting mechanism and the first rotating shaft satisfy the following relationship:

6. A robot arm as claimed in claim 3, wherein the first link is provided with a position adjustment structure for adjusting the position of the link mechanism in the length direction of the first link.

7. The mechanical arm as claimed in claim 1, wherein the one end of the balance rope is provided with a balance rope tensioning device, the other end of the spring is provided with a connecting seat, and the balance rope is connected with the connecting seat through the balance rope tensioning device so as to realize connection with the other end of the spring;

when the connecting rod assembly rotates around the first rotating shaft relative to the support, the connecting seat can move along the length direction of the support under the action of the balance rope and the spring.

8. A mechanical arm as claimed in claim 7, wherein the connecting seat is provided with a sliding block, and the support is provided with a guide rail matched with the sliding block.

9. A robotic arm as claimed in claim 1, further comprising a torque sensor arranged on the first rotational axis for detecting the rotational torque experienced by the first rotational axis.

10. A robotic arm as claimed in claim 9, further comprising a servo motor electrically connected to the torque sensor and drivingly connected to the first rotational axis; when the torque sensor detects the rotation torque applied to the first rotation shaft, the servo motor can output a corresponding compensation torque to the first rotation shaft based on the rotation torque so as to balance the rotation torque.