Heavy-load robot with two-axis and three-axis load balancing device and design method of heavy-load robot

Abstract

The invention discloses a heavy-load robot with a two-axis and three-axis load balancing device and a design method of the heavy-load robot. The heavy-load robot comprises a mechanical arm structure, a two-axis balancing cylinder and a three-axis balancing cylinder. The invention relates to the technical field of heavy-load robots, a two-shaft balance cylinder and a three-shaft balance cylinder of an industrial robot are both key components used for offsetting gravity loads generated during movement of corresponding shafts and reducing loads of a driving motor, the two-shaft balance cylinder generates opposite force through preset pressure, and the three-shaft balance cylinder is used for offsetting the gravity loads generated during movement of the corresponding shafts. The gravity of the three-axis connecting rod and the torque of a tail end load to the joint are balanced, it is ensured that the three-axis connecting rod stably moves at different angles, the three-axis balance cylinder is designed for the overturning action of the four-axis connecting rod, the gravitational torque of the four-axis connecting rod and the load is counteracted through the torque generated by air pressure, and the output power of a driving motor at the three-rotation-pair part is reduced; and the motion precision and the response speed of the robot in welding, carrying and other operations are improved.

Description

Technical Field

[0001] This invention relates to the field of heavy-duty robot technology, specifically to a heavy-duty robot with a two- or three-axis load balancing device and its design method. Background Technology

[0002] With the development of industries such as automobile manufacturing, new energy, and heavy machinery, heavy-duty tasks such as handling heavy workpieces and assembling large structural components are becoming increasingly common. For example, the handling of heavy plates in the steel industry and the assembly of large components on automobile production lines both require robots to have strong load-bearing capacity and stability. Traditional light-duty robots or simple counterweight designs cannot meet the needs of such scenarios, making the design of balancing mechanisms and balancing cylinders for heavy-duty working conditions an inevitable requirement. Directly adding counterweights (such as on parallelogram-structured robots) can easily interfere with the body structure, limiting the range of motion; moreover, the large mass of the counterweights increases the weight and size of the robot, occupies a lot of space, and may also worsen the dynamic characteristics, increasing the difficulty of motion control. If heavy-duty robots rely solely on the torque of the joint motors to overcome the eccentric gravitational torque, high-power motors must be selected, resulting in high energy consumption and large size.

[0003] While existing technologies may already offer solutions to the aforementioned problems, this case aims to provide an alternative or replacement technical solution. Summary of the Invention

[0004] To address the problems mentioned in the background art, the present invention provides the following technical solution: a device for balancing the two- and three-axis loads of a heavy-duty robot, comprising a robotic arm structure, a two-axis balancing cylinder, and a three-axis balancing cylinder; The robotic arm structure includes a two-axis base, on which a three-axis connecting rod is mounted via two rotary joints. One end of the two-axis balance cylinder is mounted on the two-axis base via a seven-rotary joint, and the other end of the two-axis balance cylinder is mounted on the three-axis connecting rod via an eight-rotary joint. One end of the three-axis connecting rod is mounted on a four-axis connecting rod via a three-rotation joint. One end of the three-axis balance cylinder is mounted on the three-axis connecting rod via a nine-rotation joint, and the other end of the three-axis balance cylinder is mounted on the four-axis connecting rod via a ten-rotation joint.

[0005] Preferably, the triaxial balance cylinder is a tension balance cylinder; A five-axis connecting rod is mounted at one end of the four-axis connecting rod via four rotary joints. The ten-revolute joint and the four-revolute joint are located on both sides of the three-revolute joint.

[0006] Preferably, the triaxial balancing cylinder is a thrust balancing cylinder; A five-axis connecting rod is mounted at one end of the four-axis connecting rod via four rotary joints. The ten-rotational joint and the four-rotational joint are both located on the same side of the three-rotational joint.

[0007] Preferably, the seventh rotary joint is located on the side of the second rotary joint opposite to the load end of the heavy-duty robot, and the two-axis balance cylinder is a tension balance cylinder.

[0008] Preferably, the dual-axis balance cylinder is a spring balance cylinder, a pneumatic balance cylinder, or a hydraulic balance cylinder; The three-axis balance cylinder is a spring balance cylinder, a pneumatic balance cylinder, or a hydraulic balance cylinder.

[0009] A method for calculating the load on two or three axes of a balanced heavy-duty robot includes the following steps: Step 1: Establish a mechanical balance model for the robot, defining key variables including the gravity of the links and loads, the distance of the lever arm from the center of gravity to the rotation axis, and the motion angle of the balance cylinder. Step 2: Based on the mechanical equilibrium model, calculate the static gravitational torque generated by the robot's own weight and load under different motion postures; Step 3: Calculate the output force of the nitrogen balancing cylinder used to balance the static gravitational torque; Step 4: Calculate the compensating torque provided by the nitrogen balance cylinder about the rotation center based on its output force and installation angle. Step 5: Calculate the remaining torque that the motor needs to bear based on the difference between the static gravitational torque and the compensation torque; Step 6: Based on the extreme values ​​of the remaining torque under different motion postures, select the drive motor and reducer.

[0010] Also includes: Step 7: Integrate the calculation method for the two- and three-axis loads of the balancing heavy-duty robot into the robot control system.

[0011] In the aforementioned steps, the establishment of the mechanical equilibrium model and / or the selection and verification of the drive motor and reducer in the steps are assisted by multibody dynamics simulation software for calculation and optimization.

[0012] In step 1, the assembly device is required before establishing the robot's mechanical balance model.

[0013] After the device is assembled, motion testing is required.

[0014] Beneficial effects This invention provides a device and calculation method for balancing the load on two and three axes of a heavy-duty robot. Compared with the prior art, it has the following advantages: The two-axis and three-axis balancing cylinders of industrial robots are key components used to counteract the gravitational load generated during the movement of the corresponding axes and reduce the load on the drive motor. The two-axis balancing cylinder generates a reverse thrust through preset pressure to balance the torque on the joint of the three-axis linkage due to its own weight and the end load, ensuring that the three-axis linkage moves smoothly at different angles. The three-axis balancing cylinder is designed for the flipping action of the four-axis linkage. It uses the torque generated by air pressure to counteract the gravitational torque of the four-axis linkage and the load, reducing the output power of the drive motor of the three rotary joint and improving the motion accuracy and response speed of the robot in welding, handling and other operations. Both the two-axis and three-axis balancing cylinders reduce joint wear and extend equipment life through the principle of force balance, and are important auxiliary devices to ensure the efficient and stable operation of the robot. Attached Figure Description

[0015] Figure 1 This is a three-dimensional structural diagram of the device for balancing the two- and three-axis loads of a heavy-duty robot according to the present invention, taken from a frontal view.

[0016] Figure 2 This is a side-view three-dimensional structural diagram of a device for balancing the two- and three-axis loads of a heavy-duty robot according to the present invention.

[0017] In the diagram: 1. Two-axis balance cylinder, 2. Three-axis balance cylinder, 3. Two-axis base, 4. Two-axis rotary joint, 5. Three-axis connecting rod, 6. Seven-axis rotary joint, 7. Eight-axis rotary joint, 8. Three-axis rotary joint, 9. Four-axis connecting rod, 10. Nine-axis rotary joint, 11. Ten-axis rotary joint, 12. One-axis base, 13. One-axis rotary joint, 14. Four-axis rotary joint, 15. Five-axis connecting rod, 16. Five-axis rotary joint, 17. Six-axis connecting rod, 18. Six-axis rotary joint. Detailed Implementation

[0018] Example 1:

[0019] Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Please see Figure 1 A device and calculation method for balancing the two-axis and three-axis loads of a heavy-duty robot, comprising a robotic arm structure, a two-axis balancing cylinder 1, and a three-axis balancing cylinder 2; It should be noted that the overall solution is based on a robotic arm structure, a two-axis balancing cylinder 1, and a three-axis balancing cylinder 2 to form a six-axis robot; The robotic arm structure includes a two-axis base 3, a three-axis connecting rod 5 mounted on the two-axis base 3 via two rotary joints 4, one end of the two-axis balance cylinder 1 mounted on the two-axis base 3 via a seven rotary joint 6, and the other end of the two-axis balance cylinder 1 mounted on the three-axis connecting rod 5 via an eight rotary joint 7. One end of the three-axis connecting rod 5 is mounted on the four-axis connecting rod 9 via the three-rotary joint 8. One end of the three-axis balance cylinder 2 is mounted on the three-axis connecting rod 5 via the nine-rotary joint 10. The other end of the three-axis balance cylinder 2 is mounted on the four-axis connecting rod 9 via the ten-rotary joint 11. It should be noted that the two-axis balancing cylinder 1 and the three-axis balancing cylinder 2 are the balancing cylinders used in this solution to balance the load of the six-axis robot. The two-axis balancing cylinder 1 generates a reverse force through preset pressure to balance the weight of the three-axis link 5 and the torque of the end load on the joint, ensuring that the three-axis link 5 moves smoothly at different angles. The three-axis balancing cylinder 2 is designed for the flipping action of the four-axis link 9. It uses the torque generated by air pressure to counteract the gravitational torque of the four-axis link 9 and the load, reducing the output power of the drive motor at the three rotary joints 8, and improving the robot's motion accuracy and response speed in welding, handling and other operations. Both the two-axis balancing cylinder 1 and the three-axis balancing cylinder 2 reduce joint wear and extend equipment life through the principle of force balance. They are important auxiliary devices to ensure the efficient and stable operation of the robot. Among them, the three-axis balance cylinder 2 is often constructed using a combination of spring assembly or pneumatic cylinder, hydraulic cylinder and lever mechanism. The cylinder bodies of the two-axis balance cylinder 1 and the three-axis balance cylinder 2 need to have high rigidity and impact resistance. High-strength alloys or composite materials are commonly used. Combined with finite element analysis and modal optimization design, the load-to-weight ratio is improved. The end cap structure of the balance cylinder with easy-to-disassemble fine-tooth nut is adopted to reduce the number of parts and reduce the installation complexity. The design of internal and external air circuits facilitates maintenance. Specifically, the robotic arm structure also includes a first-axis base 12, on which a rotary joint 13 is mounted, and a second-axis base 3 is mounted on the rotary joint 13; Specifically, a five-axis connecting rod 15 is mounted on one end of the four-axis connecting rod 9 via a four-rotary joint 14, a six-axis connecting rod 17 is mounted on one end of the five-axis connecting rod 15 via a five-rotary joint 16, and a six-rotary joint 18 is mounted on one end of the six-axis connecting rod 17. The three-axis balance cylinder 2 can be selected as a thrust balance cylinder or a pressure balance cylinder as needed. Depending on the type of balance cylinder, the position of the ten-rotary pair 11 can also be adjusted accordingly to achieve load balance.

[0021] Specifically, the three-axis balance cylinder 2 is a tension balance cylinder, and a five-axis connecting rod 15 is installed at one end of the four-axis connecting rod 9 through a four-rotary joint 14. The ten-rotary joint 11 and the four-rotary joint 14 are located on both sides of the three-rotary joint 8, respectively.

[0022] Using a tension balance cylinder as the three-axis balance cylinder 2, when there is a load at the load end where the six rotary joint 18 is located, under the action of the lever, one side of the ten rotary joint 11 has an upward tendency. The three-axis balance cylinder 2 generates tension to offset (or partially offset) the torque generated at the load end, thereby producing a torque balance effect. The three rotary joint 8 only requires a small amount of power to achieve the rotation drive of the four-axis connecting rod 9.

[0023] In another embodiment, the three-axis balance cylinder 2 is a thrust balance cylinder, and a five-axis connection rod 15 is mounted on one end of the four-axis connecting rod 9 through a four-rotary joint 14. The ten-rotary joint 11 and the four-rotary joint 14 are both located on the same side of the three-rotary joint 8.

[0024] Using a thrust balance cylinder as the three-axis balance cylinder 2, when there is a load at the load end where the six rotary joint 18 is located, under the action of the lever, one side of the ten rotary joint 11 tends to rise. The three-axis balance cylinder 2 generates thrust to offset (or partially offset) the torque generated at the load end, thereby producing a torque balance effect. The three rotary joint 8 only requires a small amount of power to achieve the rotation drive of the four-axis connecting rod 9.

[0025] Specifically, the seventh rotary joint 6 is located on the side of the second rotary joint 4 opposite to the load end of the heavy-duty robot, and the two-axis balance cylinder 1 is a tension balance cylinder.

[0026] When the three-axis connecting rod 5 is working, it may rotate to both sides of the vertical position. Using a tension balance cylinder as the two-axis balance cylinder 1 can play a tension balance role throughout the entire rotation range of the three-axis connecting rod 5, and there is no need to set the rotation range for the three-axis connecting rod 5.

[0027] Of course, a thrust balance cylinder can also be selected as the second-axis balance cylinder 1, and a rotation limit can be set for the third-axis connecting rod 5 to prevent the thrust balance cylinder from failing.

[0028] The dual-axis balance cylinder 1 can be a spring balance cylinder, a pneumatic balance cylinder, or a hydraulic balance cylinder.

[0029] Preferably, the dual-axis balancing cylinder 1 is a pneumatic balancing cylinder, which generally uses an inert gas, such as a nitrogen balancing cylinder.

[0030] The three-axis balance cylinder 2 can be a spring balance cylinder, a pneumatic balance cylinder, or a hydraulic balance cylinder.

[0031] Preferably, the three-axis balancing cylinder 2 is a pneumatic balancing cylinder, which generally uses an inert gas, such as a nitrogen balancing cylinder.

[0032] Specifically, both the two-axis balance cylinder 1 and the three-axis balance cylinder 2 include a first support seat, a cylinder body, a piston, and a second support seat connected in sequence.

[0033] I. Component Connection and Composition 1. Base and basic joints The base is the supporting foundation of the robot. The first axis (such as the waist seat component of the vertical joint axis) is installed on the base and can rotate around the base, forming the first joint pair of the robot and providing a rotational foundation for the upper structure.

[0034] 2. Two-axis connection (including nitrogen balance cylinder) The swing arm assembly of the second axis is connected to the waist seat assembly of the vertical joint axis via a slewing joint. One end of the nitrogen balancing cylinder is connected to the waist seat assembly via a shaft, lug, or support, while the other end is connected to the swing arm assembly. For example, in some designs, the balancing cylinder is mounted with bearings at both ends or with lug bearings, so that when the swing arm pitches and swings around the horizontal slewing joint, the balancing cylinder can generate a counter-torque through internal nitrogen pressure to help counteract the gravitational torque of the swing arm and the load.

[0035] 3. Three-axis connection (including nitrogen balance cylinder) The translational seat component of the third axis is mounted on the slewing joint at the front end of the swing arm. In some designs, it forms a parallelogram mechanism with the vertical joint axis waist seat component via a connecting rod. A nitrogen balancing cylinder can further assist the movement of this axis, for example, by adjusting the internal pressure to compensate for the gravitational torque of the translational seat component during movement, ensuring its stable motion posture (such as maintaining translation).

[0036] 4. Connection of subsequent components The slewing arm assembly and the translational seat assembly are connected by a vertical joint (forming the fourth joint), with its front-end slewing shaft parallel to the slewing drive axis of the translational seat assembly. The wrist arm assembly and wrist seat assembly are sequentially mounted on the front-end slewing shaft assembly of the slewing arm, forming subsequent joints. The end output flange or actuator (such as a gripper, welding torch, etc.) is mounted on the wrist seat assembly to perform specific tasks.

[0037] II. Robot Movement Methods 1. Rotation of axis 1 The first axis drives the vertical joint axis waist seat component to rotate around the base, causing the entire upper structure to rotate and adjust the robot's working position.

[0038] 2.2-axis pitch and oscillation Driven by a motor, the swing arm component of the second axis pitches and oscillates around a horizontal rotary joint mounted on the waist seat component of the vertical joint axis. At this time, the dual-axis balance cylinder responds in real time, generating a force opposite to the torque of the swing arm and the load through internal nitrogen compression or extension, reducing the motor drive load and making the swing smoother and more efficient.

[0039] 3. Three-axis translation or attitude adjustment In the case of a parallelogram mechanism design, the translational seat component of the third axis, driven by the swing arm and combined with the linkage motion, maintains a translational posture. The three-axis balance cylinder further optimizes the torque balance in this process, ensuring translational accuracy. In other structures, the balance cylinder also assists in adjusting the gravitational torque to make the motion more stable.

[0040] 4. Subsequent joint compound exercises 5. The rotary arm component rotates around the vertical joint, combined with the multi-degree-of-freedom movements (such as rotation and pitch) of the wrist arm and wrist seat components, enabling the end effector to achieve complex posture adjustments in three-dimensional space and complete tasks such as handling, assembly, and welding. Throughout the entire movement process, the two-axis and three-axis balancing cylinders continuously compensate for the gravitational torque of the two and three axes, reducing motor energy consumption and improving the stability and accuracy of robot movement. Especially under heavy-load conditions, it effectively reduces vibration and deformation, ensuring operational reliability.

[0041] Example 2: A method for calculating the load on two or three axes of a balanced heavy-duty robot includes the following steps: Step 1: Establish a mechanical equilibrium model for the robot, defining the gravity (G) including the links and load, and the lever arm distance from the center of gravity to the rotation axis. The key variables are the balance cylinder motion angle (θ), where the balance cylinder motion angle (θ) is the angle between the line connecting the tail end of the tension cylinder to the rotation center and the extension direction of the tension cylinder; Step 2: Based on the mechanical equilibrium model, calculate the static gravitational torque (F) generated by the robot's own weight and load under different motion postures. The formula for calculating the static gravitational moment (F) is: ;

[0042] Step 3: Calculate the output force of the nitrogen balancing cylinder used to balance the static gravitational torque. ); Output force of nitrogen balance cylinder ( ) through its elongation (ΔX) and compressibility ( )calculate; Output force of nitrogen balance cylinder ( The formula for calculating ) is: = ×ΔX; Step 4: Based on the output force of the nitrogen balance cylinder ( ) and its installation angle (θ), calculate the compensating torque it provides about the center of rotation ( ); Compensating torque ( The formula for calculating ) is: = × ×sin(θ) in, This refers to the lever arm length of the nitrogen balance cylinder; Step 5: Calculate the remaining torque Mremaining required by the motor based on the difference between the static gravitational torque F and the compensation torque F1. The formula for calculating the residual torque (M_residual) is: M_residual = F - F1 Step 6: Based on the extreme values ​​of the residual torque (M_residual) under different motion postures, select the drive motor and reducer; It also includes: Step 7, integrating the calculation method for the two- and three-axis loads of the balancing heavy-duty robot into the robot control system; In the steps, the establishment of the mechanical equilibrium model and / or the selection and verification of the drive motor and reducer are carried out by multibody dynamics simulation software for auxiliary calculation and optimization. In step 1, the assembly device needs to be assembled before establishing the robot's mechanical balance model; After the device is assembled, motion testing is required; In practical work, record and organize the following key values, and fill in the key values ​​in the table below;

[0043] pass The gravitational torque of the equipment with respect to the rotation center, namely the two rotary joints 4 and 8, can be calculated.

[0044] pass The output force of the balance cylinder under tension can be calculated.

[0045] pass The tension torque of the balance cylinder about the center of rotation, namely the two rotary joints 4 and 8, can be calculated. It is the angle between the line connecting the tail end of the tension cylinder to the center of rotation and the extension direction of the tension cylinder.

[0046] The range of torque difference can be calculated under different poses.

[0047] Pick This is the torque after load balancing. Then, based on this value, a suitable speed ratio between the motor and the reducer can be selected.

[0048] In the force calculation of heavy-duty robot balancing cylinders (such as two-axis balancing cylinder 1 and three-axis balancing cylinder 2), the core is to counteract the gravitational torque of the joint load through the principle of mechanical balance, ensuring that the load on the drive motor is minimized. The following are the detailed calculation methods and key formula derivations: I. Basic Mechanical Model and Variable Definitions 1. Key variables Joint load parameters: G: Weight of the link (including load) (N); L: Distance from the center of gravity of the connecting rod to the axis of rotation (lever arm, m); θ: The angle of motion of the balance cylinder (° or r14d).

[0049] Using the methods described above, the force and key variables of the balancing cylinder in heavy-duty robots can be systematically calculated, ensuring that the balancing cylinder effectively reduces motor load and improves robot motion stability and energy efficiency under different loads and motion postures. In practical engineering, further optimization is needed by combining mechanical structure simulation (such as 14D14MS) and control algorithms (such as torque compensation control).

[0050] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A heavy-duty robot with a two- or three-axis load balancing device, characterized in that, It includes a robotic arm structure, a two-axis balance cylinder (1), and a three-axis balance cylinder (2); The robotic arm structure includes a two-axis base (3), on which a three-axis connecting rod (5) is mounted via two rotary joints (4). One end of the two-axis balance cylinder (1) is mounted on the two-axis base (3) via a seven-rotary joint (6), and the other end of the two-axis balance cylinder (1) is mounted on the three-axis connecting rod (5) via an eight-rotary joint (7). One end of the three-axis connecting rod (5) is mounted on a four-axis connecting rod (9) via a three-rotary joint (8). One end of the three-axis balance cylinder (2) is mounted on the three-axis connecting rod (5) via a nine-rotary joint (10). The other end of the three-axis balance cylinder (2) is mounted on the four-axis connecting rod (9) via a ten-rotary joint (11).

2. A heavy-duty robot with a two- or three-axis load balancing device according to claim 1, characterized in that, The triaxial balance cylinder (2) is a tension balance cylinder; One end of the four-axis connecting rod (9) is fitted with a five-axis connecting rod (15) via a four-rotary joint (14). The ten-rotational joint (11) and the four-rotational joint (14) are located on both sides of the three-rotational joint (8).

3. A heavy-duty robot with a two- or three-axis load balancing device according to claim 1, characterized in that, The triaxial balancing cylinder (2) is a thrust balancing cylinder; One end of the four-axis connecting rod (9) is fitted with a five-axis connecting rod (15) via a four-rotary joint (14). The ten-rotational joint (11) and the four-rotational joint (14) are both located on the same side of the three-rotational joint (8).

4. A heavy-duty robot with a two- or three-axis load balancing device according to claim 1, characterized in that, The seventh rotary joint (6) is located on the side of the second rotary joint (4) opposite to the load end of the heavy-duty robot, and the two-axis balance cylinder (1) is a tension balance cylinder.

5. A heavy-duty robot with a two- or three-axis load balancing device according to claim 1, characterized in that, The dual-axis balance cylinder (1) is a spring balance cylinder, a pneumatic balance cylinder, or a hydraulic balance cylinder; The three-axis balance cylinder (2) is a spring balance cylinder, a pneumatic balance cylinder, or a hydraulic balance cylinder.

6. A design method for a heavy-duty robot with a two- or three-axis load balancing device, used to design the heavy-duty robot according to any one of claims 1-6, characterized in that, Includes the following steps: Step 1: Establish a mechanical balance model for the robot, defining key variables including the gravity of the links and loads, the distance of the lever arm from the center of gravity to the rotary joint, and the motion angle of the balance cylinder. Step 2: Based on the mechanical equilibrium model, calculate the static gravitational torque generated by the robot's own weight and load under different motion postures; Step 3: Calculate the output force of the balancing cylinder used to balance the static gravitational torque; Step 4: Calculate the compensating torque that the balance cylinder provides about the rotation center based on its output force and installation angle. Step 5: Calculate the remaining torque that the rotating joint needs to bear based on the difference between the static gravitational torque and the compensation torque; Step 6: Based on the extreme values ​​of the remaining torque under different motion postures, select the drive motor and reducer for the rotary joint.

7. The design method of a heavy-duty robot with a two- or three-axis load balancing device according to claim 6, characterized in that, Also includes: Step 7: Integrate the calculation method for the two- and three-axis loads of the balancing heavy-duty robot into the robot control system.

8. The design method of a heavy-duty robot with a two- or three-axis load balancing device according to claim 6, characterized in that, In the aforementioned steps, the establishment of the mechanical equilibrium model and / or the selection and verification of the drive motor and reducer in the steps are assisted by multibody dynamics simulation software for calculation and optimization.

9. The design method of a heavy-duty robot with a two- or three-axis load balancing device according to claim 6, characterized in that, In step 1, the assembly device is required before establishing the robot's mechanical balance model.

10. The design method of a heavy-duty robot with a two- or three-axis load balancing device according to claim 9, characterized in that, After the device is assembled, motion testing is required.

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