WO2014089887A1

WO2014089887A1 - Mechanical arm, control method of mechanical arm and robot

Info

Publication number: WO2014089887A1
Application number: PCT/CN2012/087876
Authority: WO
Inventors: 林天麟; 阎镜予
Original assignee: 安科智慧城市技术（中国）有限公司
Priority date: 2012-12-14
Filing date: 2012-12-28
Publication date: 2014-06-19
Also published as: CN103009401B; CN103009401A

Abstract

Disclosed is a mechanical arm, comprising at least one servo motor (10), an enclosed air bag (30) and at least one rope (40), wherein the air bag (30) comprises at least one joint; one end of each rope (40) is connected to one end (401) of one of the at least one joint, and the other end of each rope is connected to one of the at least one servo motor (10); and the position of each joint is controlled by adjusting the length of each rope (40) by the servo motor (10). In a preferred embodiment, the mechanical arm comprises at least two ropes (40), wherein one end of each rope (40) is connected to one end (401) of one of the at least one joint, and the other end of each rope is connected to one of the at least one servo motor (10); each joint is controlled by at least two ropes (40); and the control of the length of each rope (40) of each joint are coupled with each other, so that the position of the joint can be controlled. The mechanical arm is supported by the air bag (30) and is driven by a cable, such that the inertia of the mechanical arm is greatly reduced and the compliance of the mechanical arm is greatly improved, so that the mechanical arm is safer for use and is more attractive.

Description

Control method and robot for robot arm and robot arm

Technical field

The present invention relates to the field of automatic control, and more particularly to a robot arm, a control method for a robot arm, and a robot.

Background technique

The robotic arm is an automatic control device that mimics the function of the human arm and can perform various tasks. The robotic system composed of such a robotic arm is connected by multiple joints and allows movement in two or three-dimensional space or movement using linear displacement.

In the related art, the mechanical arm is generally made of a material having a very strong rigidity such as metal, and the driving motor is directly mounted on the arm, so the inertia of the arm moving is large and the compliance is lacking in the case of open loop control. , making the control of the robotic arm more difficult during the design process. In addition, when such a robot arm made of metal is in contact with a person or other objects, or when working, it is likely to cause a large injury due to a collision. The collision problem of the robot arm is more important in the service robot field. There are many uncertainties in the working environment and it is necessary to interact with people frequently, which increases the risk of unexpected collision. In response to this problem, the US-issued invention patent of US Pat. No. 8,234,949, issued on August 7, 2012, proposes a joint for driving a robot arm by a wire drive method. The servo motor can be mounted on the base of the robot arm to reduce the mechanical arm. Inertia during exercise. However, the structural members of such robot arms are still made of a rigid material, so there is still some collision damage.

Summary of the invention

The object of the present invention is to solve the problem of insufficient safety of the mechanical arm in the process of servicing the robot, and to provide a mechanical arm with high safety, which is supported by the air cylinder and driven by the cable, thereby The inertia of the robot arm is greatly reduced and the compliance of the robot arm is increased, so that the use of the robot arm is safer and more beautiful.

In order to achieve the above object, an embodiment of the present invention provides a mechanical arm, and the mechanical arm includes At least one servo motor, a closed air cylinder, at least one rope, the air raft includes at least one joint, one end of each rope is connected to the end of one of the joints, and the other end is connected to one of the servo motors, and the length of the rope is adjusted by the servo motor To control the posture of the joint.

According to an embodiment of the invention, the robot arm comprises at least two ropes, one end of each rope is connected to the end of one of the joints, the other end is connected to one of the servo motors, and each joint is controlled by at least two ropes, each The length controls of the individual ropes of the joints are coupled to each other to control the attitude of the joint.

According to an embodiment of the invention, the robot arm comprises at least two servo motors, each of which independently controls a rope.

According to one embodiment of the invention, the cross-sectional area of the joint location is less than the cross-sectional area of the other locations of the air pocket.

According to an embodiment of the invention, the robot arm further comprises a sleeve arranged to nest the rope, the sleeves being disposed inside the air pocket, the inlet of each sleeve being fixed at the top end of one of the joints, and the outlet being fixed to the machine The root of the arm.

According to an embodiment of the invention, the gas cartridge comprises at least two joints joined together, the joints being connected in a tree-like manner, a ring-shaped connection manner, or a series connection.

According to one embodiment of the invention, the joint comprises a single degree of freedom joint, the single degree of freedom joint is controlled by two ropes, and the two rope positions are equally divided by 180 degrees in the cross section of the joint.

According to an embodiment of the invention, the joint comprises a two-degree-of-freedom joint, the two-degree-of-freedom joint is controlled by at least three ropes, and the position of each of the two-degree-of-freedom joints is combined at an angle of less than 180 degrees in the cross-section of the joint Division.

According to an embodiment of the invention, the position of each of the two degrees of freedom joints is equally divided by the number of ropes in the cross section of the joint.

According to an embodiment of the invention, the robot arm comprises an air pump arranged to inflate the air cylinder, an air pressure sensor arranged to detect the air pressure, and a air pressure controller arranged to receive the air pressure command, the air pressure controller receiving the air pressure command and being issued by the air pressure sensor After the pressure signal, the air pressure in the air cylinder is controlled by the air pump to make the air pressure consistent with the air pressure command; the mechanical arm further includes an attitude controller, which is arranged to control the length of the servo motor to adjust the rope to control the posture of the joint. According to another aspect of an embodiment of the present invention, a method for controlling a mechanical arm includes the following steps:

Pressing a pneumatic command to the air pressure controller, and detecting the air pressure by the air pressure sensor and issuing a pressure signal;

After the air pressure controller receives the air pressure command and the pressure signal, the air pump inflates the air pump, and the air pressure in the air pump is controlled by the air pump or the gas valve on the air pump to make the air pressure and the air pressure command consistent; the air pressure in the air cylinder is adjusted. Afterwards, issue a gesture command;

The attitude controller receives the attitude command, and controls each servo motor to adjust the length of each rope according to the attitude command so that the posture of the joint controlled by the rope coincides with the attitude command.

According to still another aspect of an embodiment of the present invention, there is provided a robot comprising the mechanical arm as described in the above technical solution. Compared with the related art, the embodiment of the invention has the following beneficial effects: The supporting function greatly reduces the harm caused by the collision of the mechanical arm with other contact objects during the working process, and ensures the safety of the working of the mechanical arm. In addition, this kind of mechanical arm can shrink the air squat when it is not working, reduce the occupied space of the mechanical arm, and is easy to carry and transport;

(2) The mechanical arm of the embodiment of the present invention uses a mechanical design of a multi-segment joint, wherein the joint and the joint are independently controlled, and the joint adjustment is not required by the movement of other joints, when the multi-segment joint passes appropriate The combination has a high ability to imitate the movement of the human arm; it can be controlled by multiple ropes, so that the joints formed are more flexible than the single-degree-of-freedom joints in the related art, which can realize more complicated activities of the robot arm, and finally realize more robots. Features;

(4) The robot arm of the embodiment of the present invention places all the ropes inside the air cylinder, so that the manipulation process of the robot arm is more succinct, and the appearance of the mechanical arm is prevented by the exposure of a large number of ropes to the mechanical arm, so that the robot arm is used. The robot is more beautiful.

(5) The threading of the cannula of the embodiment of the present invention from the inside of the joint, particularly the center, can greatly reduce the length of the cannula that needs to be reserved due to joint activity. BRIEF abstract

1 is a schematic structural view of a mechanical arm according to a first embodiment of the present invention;

2 is a schematic structural view of a mechanical arm according to a second embodiment of the present invention;

3 is a schematic view showing a tree connection manner of a multi-segment joint according to an embodiment of the present invention;

4 is a schematic view showing a ring-shaped connection manner of a multi-segment joint according to an embodiment of the present invention;

5 is a schematic view showing a series connection manner of a multi-segment joint according to an embodiment of the present invention;

6A is a plan view showing a rope distribution of a two-degree-of-freedom joint according to an embodiment of the present invention;

6B is a front elevational view of a rope distribution of a two-degree-of-freedom joint according to an embodiment of the present invention;

6C is a side view of a rope distribution of a two-degree-of-freedom joint according to an embodiment of the present invention;

7A is a plan view showing a rope distribution of a single degree of freedom joint according to an embodiment of the present invention;

Figure 7B is a front elevational view of the rope distribution of the single degree of freedom joint of the embodiment of the present invention;

Figure 7C is a side view of the rope distribution of the single degree of freedom joint of the embodiment of the present invention;

Figure 8 is a schematic view showing the movement of a mechanical arm joint according to an embodiment of the present invention;

9 is a schematic structural view of a pneumatic control system according to an embodiment of the present invention;

FIG. 10 is a schematic structural diagram of an attitude control system according to an embodiment of the present invention; FIG.

11 is a flow chart showing a method of controlling a robot arm according to an embodiment of the present invention. Preferred embodiment of the invention

The present invention will be further described in detail below with reference to the embodiments and drawings, but the embodiments of the present invention are not limited thereto.

As shown in FIG. 1, in the first embodiment of the present invention, the robot arm includes at least one servo motor 10, an air pump 21 configured to inflate the air cylinder, a gas valve 22 configured to release the air cylinder in an inoperative state, An air pressure sensor 23 for detecting air pressure, a closed air cylinder 30, and at least one rope 40, wherein the air pump 21, the air valve 22 and the air pressure sensor 23 constitute an inflation duct for adjusting the internal air pressure of the air cylinder 30, and the inflation duct is disposed on the mechanical arm Near the root, the gas cylinder 30 includes at least one joint connected together, for example, the first joint GJ1 in Fig. 1, and the second joint, the third joint, etc., not shown in Fig. 1, each joint All controlled by at least one rope, each of which is roped One end of the cable 40 is connected to the end 401 of one of the joints, and the other end is connected to one of the servo motors 10. The length of the rope 40 is adjusted by the servo motor 10 to control the posture of the joint. When the servo motor 10 tightens the rope 40, the joint is sideways. Moving, when the servo motor 10 relaxes the rope 40, the joint returns to its original position. All of the ropes are disposed inside the gas cylinder 30. The robot arm of the embodiment of the present invention further includes a plurality of sleeves 50 arranged to nest the ropes 40, wherein only one rope 40 is nested in each sleeve 50, the sleeve 50 can be bent, but its cross-sectional area does not change during the working process, mainly to ensure the smoothness of the rope 40 stretching. By arranging the servo motor 10 at the root position of the robot arm, the embodiment of the present invention reduces the inertia of the robot arm during movement, making the robot arm easier to control and operate.

As shown in FIG. 2, in the second embodiment of the present invention, the robot arm includes at least two servo motors 10, an air pump 21 arranged to inflate the air cylinder, and a gas valve 22 arranged to release the air cylinder in an inoperative state. An air pressure sensor 23 for detecting air pressure, a closed air cylinder 30, and at least two ropes 40, wherein the air pump 21, the air valve 22 and the air pressure sensor 23 constitute an inflation duct for adjusting the internal air pressure of the air cylinder 30, and the inflation duct is disposed at Near the root of the robot arm, the gas cylinder 30 includes at least two joints joined together, for example, the first joint GJ1, the second joint GJ2 in Fig. 2, and the third joint, not shown in Fig. 2, Four joints, etc., each joint is controlled by at least two ropes, the joint controlled by two ropes is relatively flexible with respect to the joint controlled by one rope, and the joints controlled by the two ropes have higher flexibility, wherein each rope One end of 40 is connected to the end 401 of one of the joints, and the other end is connected to one of the servo motors 10, and each joint is controlled by at least two ropes, each joint The control cable length coupled with each other to control the attitude of the joint. All of the ropes are disposed inside the gas cylinder 30. The robot arm of the embodiment of the present invention further includes a plurality of sleeves 50 arranged to nest the ropes 40, wherein only one rope 40 is nested in each sleeve 50, the sleeve 50 can be bent, but its cross-sectional area does not change during the working process, mainly to ensure smooth stretching of the rope 40. The embodiment of the present invention reduces the inertia of the robot arm during movement by disposing the servo motor 10 at the root position of the robot arm, making the robot arm easier to control and operate.

In both of the above embodiments, the gas cylinder 30 is made of a material that is not stretchable or low in extension, the gas cylinder 30 is inflated by the air pump 21, and the air pressure sensor 23 is installed in the inflation duct to detect the air pressure. As shown in Figure 2, the cross-section of the joint position will be made smaller than the other positions, making the position at the joint easier to bend. All of the cords in the embodiments of the present invention are constructed of a non-extensible material, wherein the cord 40 passes through the sleeve 50, the inlet 502 of the sleeve 50 is secured to the top end of the joint, and the sleeve 50 The outlet 501 is fixed to one side of the entire robot arm, such as the root position. The sleeve 50 is constructed of a material that is only bendable and that does not change its cross-sectional shape. The position of the outlet 501 of the sleeve 50 is fixed to the servo motor 10 such that the length of the servo motor 10 pulled out of the rope coincides with the contracted length of the rope in the joint position. The combination of the joints in the embodiments of the present invention may be formed by a series connection manner, a tree connection manner, a ring shape connection manner, or any combination of the above three connection methods, wherein the gas paths between the joints are continuous. The sleeve 50 passes through the center of the other joints and finally reaches the root of the robot arm. Relative to the outside of the arm, the routing of the cannula 50 from the center of the joint greatly reduces the length of the cannula 50 that needs to be reserved for joint activity.

The principle and working mode of the embodiment of the present invention are specifically described below by taking the second embodiment as an example:

The types of mechanical arm joints include universal (two degrees of freedom) joints and single degree of freedom joints. Figure

6A to 6C show the structure of the two-degree-of-freedom joint, and Figs. 7A to 7C show the structure of the single-degree-of-freedom joint. The two-degree-of-freedom joint is controlled by a minimum of three ropes. In the case of three rope control, one of the distributions is divided by 120 degrees as shown in the cross section of Fig. 6A. Of course, there are other distribution modes, and the angles can be combined at will. Less than 180 degrees. The position of the rope of the single-degree-of-freedom joint can be equally divided by 180 degrees as shown in the cross section in Fig. 7A, and is disposed on the side of the recess of the joint, as shown in the side view in Fig. 7C, otherwise the joint activity cannot be effectively controlled. There may be more than one rope installed on each side. In the embodiment of the present invention, the joint combination in the robot arm may be composed of a plurality of single-degree-of-freedom joints, or may be a combination of a plurality of two-degree-of-freedom joints, or may be a combination of single-degree-of-freedom and two-degree-of-freedom joints. These can be set according to the actual situation.

The mechanical arm of the embodiment of the present invention mainly consists of a pneumatic control system and an attitude control system. As shown in FIGS. 9 and 10, the air pressure control system includes a closed air cylinder 30, an air pump 21 configured to inflate the air cylinder 30, an air pressure sensor 23 configured to detect air pressure, and an air pressure control configured to receive a pneumatic command. After the air pressure controller 60 receives the air pressure command and the pressure signal sent by the air pressure sensor 23, the air pressure in the air cylinder is controlled by the air pump 21 or the air valve 22 so that the air pressure is consistent with the air pressure command, and the air pressure 30 includes each other. a plurality of connected joints; the attitude control system includes at least two servo motors 10, at least two ropes 40, and an attitude controller 70, each joint having at least two rope controls, each of which has a length control of each other Coupling; each servo motor 10 independently controls each rope 40, and each servo motor 10 is controlled by the attitude controller 70 to adjust its control. The length of the rope 40 is such that the posture of the joint controlled by the at least two ropes 40 coincides with the attitude command.

As shown in Figure 11, the manipulator's control flow includes the following steps:

S101: issuing a pneumatic command to the air pressure controller, and detecting the air pressure by the air pressure sensor 23 and issuing a pressure signal;

S102: After receiving the air pressure command and the pressure signal, the air pressure controller inflates the air cylinder 30 by the air pump 21, and controls the air pressure in the air cylinder by the air pump 21 or the air valve 22 on the air cylinder 30 to make the air pressure and the air pressure The air pressure command is consistent; the air pressure adjustment can change the rigidity of the whole robot arm, thus changing the compliance of the arm. The air pressure control system can be started all the time when the arm is used, or can be started before the arm is used, ensuring that the air pressure is correct and then closed. , then use the robotic arm to save power;

S103: After adjusting the air pressure in the gas cylinder 30, an attitude command is issued;

S104: The attitude controller 70 receives the attitude command, and controls each servo motor 10 to adjust the length of each rope according to the attitude command so that the posture of the joint controlled by the rope coincides with the attitude command.

The length control of the ropes 40 of each joint is coupled, as shown in Figure 8. When a joint needs to change its posture, each rope on its joint needs to be changed accordingly, for example, in a single degree of freedom joint. The two ropes in the middle, if one of the ropes performs the relaxation command, then the other rope performs the tightening command to ensure the smooth movement of the joint here. If the other joints do not change the posture, the length of the rope remains unchanged. change.

The robot arm of the embodiment of the present invention can be applied to a robot, and the robot can be made freely movable and extremely safe.

The gas cartridge of the embodiment of the present invention may include at least two joints connected together, and the joints of the joints are a tree connection manner, a ring shape connection manner, or a series connection manner, which are respectively described in several embodiments:

Example 1

As shown in FIG. 3, the plurality of joints of the robot arm in the embodiment are combined in a tree shape, and the mechanical arm includes a robot arm root DB, a first joint GJ1, a second joint GJ2, a third joint GJ3, and a The four joint GJ4 and the air pump 21, the air valve 22, the air pressure sensor 23, the air pressure controller 60, the closed air cylinder 30, the plurality of servo motors 10, and the plurality of ropes 40 not shown in FIG. 3, this embodiment The joints in the joint are not only four, but may be more joints, wherein the roots DB of the robot arm, the first joint GJ1, the second joint GJ2, the third joint GJ3, and the fourth joint GJ4 are sequentially connected, and each joint is at least Two ropes are controlled, wherein one end of each rope 40 is connected to the end 401 of one of the joints, the other end is connected to one of the servo motors 10, and all the ropes are disposed inside or in the center of the gas cylinder 30, in the embodiment of the present invention The robot arm further includes a plurality of sleeves 50 arranged to nest the ropes 40, wherein each of the sleeves 50 is nested with only one rope 40, and the sleeve 50 can be bent, but the cross-sectional area is not during the working process. changes happened.

In this embodiment, there may be a plurality of joints, not only four joints, and some of the joints are laterally disposed, and the other joints are longitudinally disposed. For example, as shown in Fig. 3, the first joint GJ1 and the third joint GJ3 are disposed laterally, and the second joint GJ2 and the fourth joint GJ4 are longitudinally disposed.

In this embodiment, the type of all the joints may be a single-degree-of-freedom joint or a two-degree-of-freedom joint. The specific situation is determined according to the actual situation, and is not specifically limited in this embodiment. The mechanical arm in this embodiment is mainly composed of a pneumatic control system and an attitude control system. The air pressure control system can be activated all the time when the arm is in use, or it can be started before the arm is used to ensure that the air pressure is correct and then closed, and then the arm is used to save power. The air pressure controller 60 receives the pressure signal detected by the air pressure command and the air pressure sensor 23, and then controls the air pump 21 and the air valve 22 to control the air pressure in the air cylinder 30 to coincide with the air pressure command. The adjustment of the air pressure changes the rigidity of the entire arm, thereby changing the compliance of the arm.

The attitude controller 70 adjusts the length of the rope 40 on the joint by controlling the servo motor 10 so that the posture of the arm is matched with the command. The length control of the ropes of each joint is coupled. When a joint needs to change its posture, each rope on its joint needs to be changed accordingly. If the other joints do not change their posture, the length of the rope remains the same.

Example 2

As shown in FIG. 4, the plurality of joints of the robot arm in the present embodiment are combined in a ring shape, and the mechanical arm includes a robot arm root DB, a first joint GJ1, a second joint GJ2, and a third joint GJ3, Four joint GJ4, fifth joint GJ5, sixth joint GJ6, and air pump 21, air valve 22, air pressure sensor 23, air pressure controller 60, closed air cylinder 30, multiple servo motors 10, and more are not shown in FIG. The rope 40, the joint in this embodiment is not only six, but may be more joints, wherein the first joint GJ1, the second joint GJ2, the third joint GJ3, the fourth joint GJ4, the fifth joint The GJ5 and the sixth joint GJ6 together form a ring-shaped joint combination, and may be a combination of joints in which three or more joints are combined to form a ring shape, or may be combined into a plurality of ring-shaped joint combinations that are connected together. It depends on the actual situation. Similarly, in this embodiment, the type of all the joints may be a single-degree-of-freedom joint or a two-degree-of-freedom joint. The specific situation is determined according to the actual situation, and is not specifically limited in this embodiment. Other technical solutions in this embodiment are the same as those in Embodiment 1, and are not described herein again.

Example 3

As shown in FIG. 5, the plurality of joints of the robot arm in the embodiment are connected in series, and the robot arm includes a robot arm root DB, a first joint GJ1, a second joint GJ2, and a third joint GJ3 which are sequentially connected. In this embodiment, the joints are not only three, but may be more, wherein all the joints are either horizontally disposed or longitudinally disposed. Other technical solutions in this embodiment are the same as those in Embodiment 1, and are not described herein again.

In summary, the mechanical arm shack provided by the embodiment of the invention uses a closed air raft as a support, which reduces the damage caused by the collision of the mechanical arm with other contact objects during work and transportation, and also has multiple segments. The combination of multiple degrees of freedom controls the movement of the arm and the ropes are built into the air, making the arm more flexible and more aesthetically pleasing. The robot arm of the embodiment of the present invention can also be applied to a motion robot or a avatar robot.

The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and modifications made without departing from the spirit and scope of the present invention. Simplifications, which are equivalent replacement means, are included in the scope of the present invention.

Industrial applicability

The function greatly reduces the harm caused by the collision of the mechanical arm with other contact objects during the working process, and ensures the safety of the working of the mechanical arm. In addition, the mechanical arm can contract the gas when not working.嚢, the occupied space of the mechanical arm is reduced, and the carrying and transporting is convenient; the mechanical arm of the embodiment of the invention uses the mechanical arm design of the multi-segment joint, wherein the joint and the joint are independently controlled, and no movement of other joints is required. And make the corresponding adjustments, when the multi-segment joints have passed the appropriate combination Highly imitating the mobility of the human arm; the joint for the arm of the embodiment of the present invention can have multiple degrees of freedom, that is, a single joint can be controlled by a plurality of ropes, and the joint thus constructed is more than a joint of a single degree of freedom in the related art. More flexible, more complex activities of the robot arm can be realized, and finally more functions of the robot can be realized; the mechanical arm of the embodiment of the invention places all the ropes inside the air cylinder, so that the manipulation process of the robot arm is more concise and avoids a large number of ropes The exposure of the mechanical arm affects the appearance of the mechanical arm, so that the robot using the mechanical arm is more beautiful; the thread of the casing of the embodiment of the invention passes through the inside of the joint, especially the center, which can greatly reduce the casing due to joint activity. The length to be reserved. Therefore, the present invention has strong industrial applicability.

Claims

claims

1. A robotic arm, including: at least one servo motor, a closed airbag, and at least one rope. The airbag includes at least one joint. One end of each rope is connected to the end of one of the joints, and the other end is connected to one of the joints. A servo motor is connected, and the servo motor adjusts the length of the rope to control the posture of the joint.

2. The robotic arm according to claim 1, wherein the robotic arm includes at least two ropes, one end of each rope is connected to the end of one of the joints, and the other end is connected to one of the servo motors, and each joint is It is controlled by at least two ropes, and the length control of each rope of each joint is coupled with each other to control the posture of the joint.

3. The robotic arm according to claim 2, wherein the robotic arm includes at least two servo motors, each servo motor independently controlling a rope.

4. The robotic arm according to claim 1 or 2, wherein the cross-sectional area of the joint position is smaller than the cross-sectional area of other positions of the airbag.

5. The robotic arm according to claim 1 or 2, wherein the robotic arm further includes a sleeve configured to nest the rope, and the sleeves are arranged inside the airbag, and each The inlet of the casing is fixed at the top of one of the joints, and the outlet is fixed at the root of the mechanical arm.

6. The robotic arm according to claim 1 or 2, wherein the air bag includes at least two joints connected together, and the connection mode of the joints is a tree-shaped connection mode, a ring-shaped connection mode, or a series connection mode.

7. The robotic arm according to claim 2, wherein the joint includes a single degree of freedom joint, the single degree of freedom joint is controlled by two ropes, and the positions of the two ropes are 180 degrees in the cross section of the joint. Equally divided.

8. The robotic arm according to claim 2, wherein the joints comprise two-degree-of-freedom joints, the two-degree-of-freedom joints are controlled by at least three ropes, and the positions of each rope in the two-degree-of-freedom joints are The cross section of the joint is divided by an angle combination of less than 180 degrees.

9. The robotic arm according to claim 8, wherein the position of each rope in the two-degree-of-freedom joint is equally divided by the number of the ropes in the cross section of the joint.

10. The robotic arm according to claim 1 or 2, wherein the robotic arm includes an air pump configured to inflate the air bag, an air pressure sensor configured to detect air pressure, and an air pressure controller configured to receive air pressure instructions. , after the air pressure controller receives the air pressure command and the pressure signal sent by the air pressure sensor, the air pump controls the air pressure in the air bag to make the air pressure consistent with the air pressure command; the robotic arm also includes an attitude controller , configured to control the servo motor to adjust the length of the rope to control the attitude of the joint.

11. A robot comprising a robotic arm according to any one of claims 1-10.

12. A control method for a robotic arm, including the following steps:

Issue air pressure commands to the air pressure controller, and the air pressure sensor detects the air pressure and sends out a pressure signal;

After the air pressure controller receives the air pressure command and pressure signal, the air pump inflates the air bag, and the air pump or the air valve on the air bag controls the air pressure in the air bag so that the air pressure is consistent with the air pressure command. ;

After adjusting the air pressure in the air bag, issue the attitude command;

The posture controller receives the posture command and controls each servo motor to adjust the length of each rope according to the posture command so that the posture of the joint controlled by the rope is consistent with the posture command.