Mechanical arm boundary limiting method and system

Abstract

The invention belongs to the technical field of mechanical arm control, and discloses a mechanical arm boundary limiting method and system.The method comprises the steps that real-time motion parameters of all joints of a target mechanical arm are obtained, and the motion parameters comprise real-time feedback positions; whether the real-time feedback position exceeds the boundary value of the mechanical arm or not is judged, if the real-time feedback position exceeds the boundary value of the mechanical arm, a boundary limiter of the corresponding joint is enabled, and an instruction correction value of the boundary limiter is calculated; and acquiring an issuing instruction of the user, and determining an output instruction corresponding to the boundary limiter based on the issuing instruction and the instruction correction value. By the adoption of the limiting method, the speed reduction and position keeping functions when the mechanical arm exceeds the boundary can be achieved, the deployment cost is low, safety is high, and the danger caused when the mechanical arm exceeds the boundary due to an abnormal current / torque instruction can be effectively prevented.

Description

Technical Field

[0001] The present invention belongs to the technical field of robotic arm control, and in particular, relates to a method and system for limiting the boundaries of a robotic arm. Background Art

[0002] In existing technical solutions, most manufacturers do not directly open the current / torque mode to users. Instead, they receive the trajectories sent by users and then implement current / torque control through control algorithms (such as PID control, adaptive control, and optimal control, etc.) at the servo level. This control method cannot achieve direct current / torque control. With the popularity of humanoid robots, more and more developers of humanoid robots expect to achieve current / torque control of the robotic arm through their own controllers for the safety of human-robot collaboration. Therefore, robotic arm manufacturers need to provide current / torque control interfaces to the outside.

[0003] In the existing current / torque control mode, similar to open-loop or semi-closed-loop control, the controller only performs amplitude limiting processing on the received current / torque at the bottom layer and has no other processing. Therefore, when the user accidentally sends inappropriate current / torque control instructions, the robotic arm may exceed the normal working space and cross the boundary, which may lead to equipment damage or safety problems. Summary of the Invention

[0004] (1) Object of the Invention

[0005] The object of the present invention is to provide a method and system for limiting the boundaries of a robotic arm, which can keep the robotic arm within the normal working space, thereby improving the safety and usability of this function. Through current / torque control, the robotic arm can apply different currents / torques in different directions, increasing the flexibility of operation. In addition, current / torque control allows the robotic arm to adapt to changes in the external environment, which can help the robotic arm and people work more safely.

[0006] (2) Technical Solution

[0007] To solve the above problems, the first aspect of the present invention provides a method for limiting the boundaries of a robotic arm, which includes:

[0008] Obtain the real-time motion parameters of each joint of the target robotic arm, and the motion parameters include real-time feedback positions;

[0009] Judge whether the real-time feedback position exceeds the boundary value of the robotic arm. If it exceeds the boundary value of the robotic arm, enable the boundary limiter of the corresponding joint and calculate the command correction value of the boundary limiter;

[0010] Obtain the instruction sent by the user, and based on the sent instruction and the instruction correction value, determine the corresponding output instruction of the boundary limiter to perform multi-mode limitation on the robotic arm.

[0011] Further, the issued instructions include: current / torque instructions, torque and desired position instructions, and torque and desired speed instructions.

[0012] Further, the motion parameters further include the real-time feedback speed and the real-time feedback acceleration.

[0013] Further, the calculation formula for the instruction correction value of the boundary limiter is as follows:

[0014]

[0015] In the formula, τ wall is the instruction correction value of the boundary limiter, q err is the deviation between the real-time feedback position and the manipulator boundary value, q target is the manipulator boundary value, q represents the real-time feedback position of the joint, q is the real-time feedback speed of the joint, k1 is the position stiffness parameter of the boundary limiter, and Δq is the deviation q between the real-time feedback position and the manipulator boundary value err and the difference between the real-time feedback speed q, dt is the control period, k2 is the speed stiffness parameter of the boundary limiter, k3 is the speed damping parameter of the boundary limiter, and Δq last is the Δq at the previous sampling moment, and τ g is the manipulator gravity compensation value.

[0016] Further, based on the issued instruction and the instruction correction value, determining the corresponding output instruction of the boundary limiter includes:

[0017] If the issued instruction is a current instruction, then convert the instruction correction value into current and output it;

[0018] If the issued instruction only has a torque instruction, then the output instruction is: τ out = τ cmd + τ wall ;

[0019] If the issued instruction is a torque and desired position instruction, then compare the desired position instruction with the manipulator boundary value to determine the output instruction;

[0020] If the issued instruction is a torque and desired speed instruction, then compare the desired speed instruction with the real-time feedback speed corresponding to when the manipulator boundary value is exceeded to determine the output instruction;

[0021] In the formula, τ out is the output instruction, and τ cmd is the torque instruction.

[0022] Further, comparing the desired position instruction with the manipulator boundary value to determine the output instruction includes:

[0023] If q min ≤ qd ≤q max , then output the torque command τ cmd ;

[0024] If q d >q max or q d <q min , then output the command τ out =τ wall ;

[0025] Among them, q d is the desired position command, and q target includes the joint maximum boundary q max and the joint minimum boundary q min .

[0026] Furthermore, compare the desired velocity command with the velocity corresponding to when exceeding the manipulator boundary value, and the determined output command includes:

[0027] If the desired velocity command and the sign of the real-time feedback velocity q corresponding to the manipulator boundary value q target are different, then output the torque command τ cmd ;

[0028] If the desired velocity command and the sign of the real-time feedback velocity q corresponding to the manipulator boundary value q target are the same, then output the command τ out =τ wall .

[0029] Furthermore, the issued commands include the simultaneous limit mode and the non-simultaneous limit mode;

[0030] If it is the simultaneous limit mode, enable the boundary limiters of all joints;

[0031] If it is the non-simultaneous limit mode, only enable the boundary limiters of the joints exceeding the boundary.

[0032] Furthermore, the calculation formula for the manipulator gravity compensation value is as follows:

[0033]

[0034] In the formula, τ link is the link dynamic torque, M(q) is the robot inertia parameter matrix, is the Coriolis force and centrifugal force term, G(q) is the gravity torque, represents the joint real-time feedback acceleration (real-time feedback acceleration).

[0035] The second aspect of the present invention provides a robotic arm boundary limiting system, which includes:

[0036] A motion parameter acquisition module for acquiring real-time motion parameters of each joint of a target robotic arm, where the motion parameters include real-time feedback positions;

[0037] A judgment module for judging whether the real-time feedback position exceeds the robotic arm boundary value. If it exceeds the robotic arm boundary value, the boundary limiters of each joint are enabled, and an instruction correction value of the boundary limiter is calculated;

[0038] An instruction output module for acquiring a user's issued instruction and determining a corresponding output instruction of the boundary limiter based on the issued instruction and the instruction correction value.

[0039] Further, the judgment module includes an instruction correction value calculation unit for calculating the instruction correction value of the boundary limiter, and the calculation formula is as follows:

[0040]

[0041] Further, the instruction output module further includes:

[0042] A current instruction unit for converting the instruction correction value into current and outputting it if the issued instruction is a current instruction;

[0043] A torque instruction unit for outputting an instruction of: τ out = τ cmd + τ wall ;

[0044] A first mixed instruction unit for judging that if the issued instruction is a torque and desired position instruction, comparing the desired position instruction with the robotic arm boundary value to determine the output instruction;

[0045] A second mixed instruction unit for judging that if the issued instruction is a torque and desired velocity instruction, comparing the desired velocity instruction with the real-time feedback velocity corresponding to when the robotic arm boundary value is exceeded to determine the output instruction.

[0046] Further, the first mixed instruction unit is used for:

[0047] If q min ≤ q d ≤ q max , then output the torque instruction τ cmd ;

[0048] If q d > q max or q d < q min, then output the instruction τ out = τ wall ;

[0049] Furthermore, the second mixing instruction unit is used for:

[0050] If the desired speed instruction and the real-time feedback speed corresponding to the value q exceeding the robotic arm boundary target have different signs, then output the torque instruction τ ; cmd ;

[0051] If the desired speed instruction and the real-time feedback speed corresponding to the value q exceeding the robotic arm boundary target have the same sign, then output the instruction τ out = τ wall .

[0052] (III) Beneficial effects

[0053] The above technical solution of the present invention has the following beneficial technical effects: The present invention provides a robotic arm boundary limiting method and system, and for the first time proposes a robotic arm boundary limiting method under a current / torque control mode. Using the limiting method of the present invention can achieve the functions of speed reduction and position holding when the robotic arm exceeds the boundary, and can continue to respond to the current / torque instructions issued by the user when the instruction enables the robotic arm to return to the normal working space. The principle is as follows: First, obtain the real-time motion parameters of each joint of the target robotic arm, including the real-time feedback position; then judge whether the real-time feedback position exceeds the robotic arm boundary value. If it does not exceed the robotic arm boundary value, the boundary limiter of the joint is not enabled. If it exceeds the robotic arm boundary value, that is, exceeds the normal working space, the boundary limiter of the corresponding joint is enabled, and the instruction correction value of the boundary limiter is calculated; finally, based on the issued instruction and the instruction correction value, the corresponding output instruction of the boundary limiter is determined to prevent the robotic arm from exceeding the limit, thereby causing damage to the equipment or safety problems. The present invention can play a good role in boundary constraint, and even in the case where a small probability joint exceeds the boundary constraint, the present invention can also pull the position back within the joint boundary constraint, having strong constraint ability and correction ability. The present invention has low deployment cost and high safety, and can effectively prevent the danger caused by the robotic arm exceeding the boundary due to abnormal current / torque instructions. Description of the Drawings

[0054] Figure 1 is a schematic flow chart of a robotic arm boundary limiting method of the present invention;

[0055] Figure 2 is a position comparison diagram of a specific embodiment of the present invention;

[0056] ​Figure 3 is a torque command comparison diagram of a specific embodiment of the present invention;

[0057] Figure 4 is a schematic flow diagram of a robotic arm boundary limitation system of the present invention. Specific Embodiments

[0058] To make the objectives, technical solutions, and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present invention. In addition, in the following descriptions, the descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present invention.

[0059] The robotic arm current / torque control mode is an advanced control strategy that allows the robotic arm to precisely control the current / torque when performing tasks. Through current / torque control, the robotic arm can apply different currents / torques in different directions, increasing the flexibility of operation; in addition, current / torque control allows the robotic arm to adapt to changes in the external environment. For example, in a component assembly scenario, if encountering resistance, the robotic arm can adjust the torque to adapt to changes in the external environment; in an environment of cooperation with humans, torque control can limit the force applied to humans or objects, so it can help the robotic arm and humans work more safely.

[0060] As Figure 1 shown, the present invention provides a robotic arm boundary limitation method, which includes:

[0061] S1, obtaining real-time motion parameters of each joint of the target robotic arm, where the motion parameters include real-time feedback position q; the motion parameters also include real-time feedback speed and real-time feedback acceleration .

[0062] S2, determining whether the real-time feedback position exceeds the robotic arm boundary value. If it exceeds the robotic arm boundary value, enable the boundary limiter of the corresponding joint and calculate the command correction value of the boundary limiter. The robotic arm boundary value (also called the limiting wall) is defaulted to the maximum or minimum boundary of each joint, and can also be set by the user. According to the size of the real-time feedback position and the robotic arm boundary value, determine whether to enable the boundary limiter of each joint. Specifically: if the real-time feedback position q does not exceed the robotic arm boundary value; then do not enable the boundary limiter of the corresponding joint; if the real-time feedback position q exceeds the robotic arm boundary value, then enable the boundary limiter of the corresponding joint. The robotic arm boundary value is q target , q target includes the joint maximum boundary q max and the joint minimum boundary q min。In the existing technical solution, the limiter is implemented in the form of joint impedance. For example, it is usually calculated using the following formula (5):

[0063]

[0064] In formula (5), τ control is the braking command value of the boundary limiter, is the real-time feedback speed of the joint, k v is the differential gain parameter preset by the boundary limiter, q stop is the stop angle value, q represents the real-time feedback position of the joint, k q is the proportional parameter gain preset by the boundary limiter. Although the calculation scheme using formula (5) realizes the deceleration and boundary constraint of the joint to a certain extent, the constraint ability is poor, and there is no assistance from the dynamics of the robotic arm. There is still a high probability of problems such as joint over-limitation during use. In view of the above problems, the present invention proposes the following improvements. The calculation formula for the command correction value of the boundary limiter in the present invention is as follows:

[0065]

[0066] In formula (1), τ wall is the command correction value of the boundary limiter, q err is the deviation between the real-time feedback position and the robotic arm boundary value, q target is the robotic arm boundary value, q represents the real-time feedback position of the joint, is the real-time feedback speed of the joint, k1 is the position stiffness parameter of the boundary limiter, Δq is the deviation between the real-time feedback position and the robotic arm boundary value q err and the difference between the real-time feedback speed q, dt is the control period, k2 is the speed stiffness parameter of the boundary limiter, k3 is the speed damping parameter of the boundary limiter, Δq last is the Δq at the previous sampling moment, τ g is the robotic arm gravity compensation value. Through the above improvements, the present invention can better play a boundary constraint role, and even in the case of a small probability that the joint exceeds the boundary constraint, this solution can pull the position back within the joint boundary constraint, with strong constraint ability and correction ability.

[0067] The robotic arm gravity compensation value τ in formula (1) g is obtained from the dynamic model of the robot. Before step S2, the dynamic model of the robot is established. The calculation formula of this dynamic model is:

[0068]

[0069] In formula (2), τ linkis the dynamic torque of the connecting rod, M(q) is the robot inertia parameter matrix, is the Coriolis force and centrifugal force term, G(q) is the gravity torque, and q represents the real-time feedback position of the joint; is the real-time feedback speed of the joint, is the real-time feedback acceleration of the joint. The gravity compensation value τ of the robotic arm g is calculated as follows:

[0070] τ g = τ link (q, 0, 0)

[0071] = G(q); (3)

[0072] S3, obtain the issued instruction of the user, and determine the corresponding output instruction of the boundary limiter based on the issued instruction and the instruction correction value. The issued instruction includes: current / torque instruction, torque and desired position instruction, torque and desired speed instruction. Each issued instruction includes two modes: simultaneous restriction mode and non-simultaneous restriction mode. Specifically, as follows: If it is the simultaneous restriction mode, enable the boundary limiters of all joints, that is, under this mode, all axes are constrained simultaneously. As long as one joint exceeds the boundary, motion restriction is performed on all joints simultaneously; if it is the non-simultaneous restriction mode, only enable the boundary limiter of the joint that exceeds the boundary, that is, the boundary limiter only performs motion constraint on the joint that exceeds the boundary. In addition, if the issued instruction is a torque and desired position instruction, that is, the limiter is allowed to receive the desired position q d , then it will simultaneously receive the desired position q issued by the user d ; if the issued instruction is a torque and desired speed instruction, that is, the limiter is configured to allow acceptance of the desired speed q d , then it will simultaneously receive the desired speed q issued by the user d .

[0073] Furthermore, in step S3: determining the corresponding output instruction of the boundary limiter based on the issued instruction and the instruction correction value includes the following four cases:

[0074] 1. If the issued instruction is a current instruction, convert the instruction correction value into current and output it, that is, convert τ wall into current I wall ;

[0075] 2. If the issued instruction is only a torque instruction, when the boundary limiter is enabled, the output instruction is:

[0076] τ out = τ cmd + τ wall ; (4)

[0077] 3. If the issued instruction is a torque and desired position instruction, when the boundary limiter is enabled, compare the desired position instruction with the robotic arm boundary values to determine the output instruction, which is divided into two cases:

[0078] 3.1 If the desired position instruction q d is within q max and q min , then output the torque instruction τ cmd , that is:

[0079] q min ≤q d ≤q max , then output the torque instruction τ cmd ;

[0080] 3.2 If the desired position instruction q d is not within q max and q min , that is:

[0081] If q d > q max or q d < q min , then output the instruction τ out = τ wall ;

[0082] Among them, τ out is the output instruction, τ cmd is the torque instruction, q d is the desired position instruction, q target includes the joint maximum boundary q max and the joint minimum boundary q min .

[0083] 4. If the issued instruction is a torque and desired velocity instruction, then compare the desired velocity instruction with the real-time feedback velocity corresponding to when exceeding the robotic arm boundary values to determine the output instruction, including the following two cases:

[0084] 4.1 If the signs of the desired velocity instruction and the real-time feedback velocity q corresponding to exceeding the robotic arm boundary value q target are different, then output the torque instruction τ cmd . Different signs indicate that the current motion direction is the direction towards the inside of the boundary.

[0085] 4.2 If the signs of the desired velocity instruction and the real-time feedback velocity q corresponding to exceeding the robotic arm boundary value q target are the same, then output the instruction τ out = τ wall . The same signs indicate that the current motion direction is the direction towards the outside of the boundary.

[0086] According to the discrimination of symbols, unilateral control of constraints can be realized. That is, when the boundary is exceeded, if the command movement direction is still outward from the boundary, the boundary limiter acts; if the command movement direction is inward from the boundary, the boundary constraint fails and normal commands are allowed to be accepted.

[0087] The present invention will be described below in conjunction with specific embodiments, and the embodiments are as follows:

[0088] Taking joint 5 of a six-degree-of-freedom robotic arm as an example, the user controller adopts joint impedance control. The impedance stiffness kp of the controller is set to 15 Nm / rad, the damping kd is set to 0.8 Nm / (rad·sec), the motion trajectory is a sine trajectory between -90° and 90°, assuming the joint limit is ±60°, and the boundary wall parameters k1 = 2.0, k2 = 2.0, k3 = 0.5 are set. The effects of the present invention are as Figure 2 、 Figure 3 shown. Figure 2 Figure is a comparison between the ideal trajectory and the feedback position after being restricted by the boundary. It can be seen from Figure 2 that when the position exceeds ±60°, the feedback position can be restricted to remain stationary at the boundary, and when a command is issued to make the joint move into the normal working space, the feedback position will continue to track the ideal position. Figure 3 Figure is a comparison between the desired torque command corresponding to the ideal trajectory and the actual torque command after being restricted by the boundary. Combining Figure 2 it can be known that between 1.93 s and 3.08 s, since it is the normal working space, the boundary limiter does not act, and at this time the desired torque command and the actual torque command coincide; between 3.08 s and 4.44 s, at this time the trajectory exceeds the boundary limit of -60°, and the boundary limiter starts to act, so there is a large difference between the actually issued torque command and the desired torque command. Looking at the two figures together, it can be shown that the boundary limiter can limit the position within the allowable motion range (i.e., within the boundary wall) and will not exceed the boundary wall (limiting wall).

[0089] As Figure 4 shown, the second aspect of the present invention provides a robotic arm boundary control system, which includes:

[0090] A motion parameter acquisition module 21 for acquiring the real-time motion parameters of each joint of the target robotic arm, and the motion parameters include real-time feedback position;

[0091] A judgment module 22 for judging whether the real-time feedback position exceeds the robotic arm boundary value. If it exceeds the robotic arm boundary value, the boundary limiters of each joint are enabled, and the command correction value of the boundary limiter is calculated;

[0092] The instruction output module 23 is used to obtain the issued instructions of the user, and based on the issued instructions and the instruction correction value, determine the corresponding output instructions of the boundary limiter to perform multi-mode limitation on the robotic arm.

[0093] Further, the judgment module 22 includes an instruction correction value calculation unit 221, and the instruction correction value calculation unit is used to calculate the instruction correction value of the boundary limiter. The calculation formula is as follows:

[0094]

[0095] Further, the instruction output module 23 further includes:

[0096] The current instruction unit 231 is used to convert the instruction correction value into current and output it if the issued instruction is a current instruction;

[0097] The torque instruction unit 232 is used to output the instruction as: τ out =τ cmd +τ wall ;

[0098] The first hybrid instruction unit 233 is used to judge that if the issued instruction is a torque and desired position instruction, compare the desired position instruction with the robotic arm boundary value to determine the output instruction; the first hybrid instruction unit specifically includes:

[0099] If q min ≤q d ≤q max Then output the torque instruction τ cmd ;

[0100] If q d >q max Or q d <q min Then output the instruction τ out =τ wall ;

[0101] The second hybrid instruction unit 234 is used to judge that if the issued instruction is a torque and desired speed instruction, compare the desired speed instruction with the real-time feedback speed corresponding to when exceeding the robotic arm boundary value to determine the output instruction. The second hybrid instruction unit specifically includes:

[0102] If the desired speed instruction And the real-time feedback speed q corresponding to exceeding the robotic arm boundary value q target Have different signs, then output the torque instruction τ cmd ;

[0103] If the desired speed instruction The real-time feedback speed corresponding to the value of q that exceeds the manipulator boundary value target is the same as the sign of, then output the command τ out = τ wall .

[0104] The present invention provides a manipulator boundary limitation method and system, and for the first time proposes a manipulator boundary limitation method under a current / torque control mode. In this limitation method, when the real-time feedback position exceeds the manipulator boundary value, the boundary limiter of the corresponding joint is enabled, and the command correction value of the boundary limiter is calculated. Combining with the command issued by the user, the corresponding output command is determined. The commands issued include: current / torque commands, torque and desired position commands, torque and desired speed commands, etc. Each of these commands includes two modes: simultaneous limitation mode and non-simultaneous limitation mode. When in the simultaneous limitation mode, the boundary limiters of all joints are enabled. When in the non-simultaneous limitation mode, only the boundary limiters of the joints that exceed the boundary are enabled. The output commands corresponding to the commands issued in each case are different. According to different output commands, the functions of decelerating and maintaining the position when the manipulator exceeds the boundary can be realized, and when the command can make the manipulator return to the normal working space, it can continue to respond to the current / torque commands issued by the user. The present invention has a low deployment cost and high safety, and can effectively prevent the danger caused by the manipulator exceeding the boundary due to abnormal current / torque commands.

[0105] ​The present invention has been described above with reference to the embodiments of the present invention. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention. The scope of the present invention is defined by the appended claims and their equivalents. Without departing from the scope of the present invention, those skilled in the art can make various substitutions and modifications, and these substitutions and modifications should fall within the scope of the present invention. Although the embodiments of the present invention have been described in detail, it should be understood that various changes, substitutions, and alterations can be made to the embodiments of the present invention without departing from the spirit and scope of the present invention. Obviously, the above embodiments are merely examples for clear illustration and are not limitations on the embodiments. For those of ordinary skill in the art, other different forms of changes or variations can be made based on the above description. It is not necessary and impossible to enumerate all the embodiments here. The obvious changes or variations derived therefrom are still within the protection scope of the present invention. Those skilled in the art should understand that the embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk memory, CD-ROM, optical memory, etc.) containing computer-usable program code. The present invention is described with reference to the flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to the embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be realized by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing devices generate a device for realizing the functions specified in one process Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks. These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, such that the instructions stored in the computer-readable memory generate a manufactured article including an instruction device that realizes the functions specified in one process Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks. These computer program instructions can also be loaded onto a computer or other programmable data processing device, such that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process, so that the instructions executed on the computer or other programmable device provide for realizing the functions specified in one process Figure 1One process or multiple processes and / or boxes Figure 1 Steps of the functions specified in one box or multiple boxes. Those of ordinary skill in the art can understand that all or part of the steps in implementing the methods of the above embodiments can be completed by instructing relevant hardware through a program. The program can be stored in a computer-readable storage medium. When the program is executed, it includes the processes of the embodiments of the above various methods. Among them, the storage medium can be a magnetic disk, an optical disk, a read-only memory (ROM for short), or a random access memory (RAM for short), etc. The steps in the method of the embodiment of the present invention can be adjusted, combined, and deleted according to actual needs. The modules [units] in the system [terminal or device] of the embodiment of the present invention can be combined, divided, and deleted according to actual needs.

Claims

1. A method for limiting the boundary of a robotic arm, characterized in that, The method includes: Obtaining real-time motion parameters of each joint of the target robotic arm, where the motion parameters include real-time feedback position; Judging whether the real-time feedback position exceeds the robotic arm boundary value. If it exceeds the robotic arm boundary value, enable the boundary limiter of the corresponding joint and calculate the command correction value of the boundary limiter; Obtaining the issued command of the user, and based on the issued command and the command correction value, determining the corresponding output command of the boundary limiter to perform multi-mode limitation on the robotic arm.

2. The robotic arm boundary limitation method according to claim 1, wherein The issued command includes: current / torque command, torque and desired position command, torque and desired speed command.

3. The robotic arm boundary limit method according to claim 1, wherein The motion parameters further include real-time feedback speed and real-time feedback acceleration.

4. The robotic arm boundary limiting method according to claim 3, wherein The calculation formula for the command correction value of the boundary limiter is as follows: where τ wall is the instruction correction value of the boundary limiter, q err is the deviation between the real-time feedback position and the robotic arm boundary value, q target is the robotic arm boundary value, q represents the real-time feedback position of the joint, q is the real-time feedback speed of the joint, k1 is the position stiffness parameter of the boundary limiter, Δq is the deviation q err between the derivative of and the real-time feedback speed difference, dt is the control period, k2 is the speed stiffness parameter of the boundary limiter, k3 is the speed damping parameter of the boundary limiter, Δq last is the Δq at the previous sampling moment, τ g is the gravitational compensation value of the robotic arm.

5. The robotic arm boundary limitation method according to claim 2, characterized in that The determining the corresponding output command of the boundary limiter based on the issued command and the command correction value includes: If the issued command is a current command, convert the command correction value into current and output it; If the issued command only has a torque command, the output command is: τ out = τ cmd + τ wall ; If the issued command is a torque and desired position command, compare the desired position command with the robotic arm boundary value to determine the output command; If the issued command is a torque and desired speed command, compare the desired speed command with the real-time feedback speed corresponding to when the robotic arm boundary value is exceeded to determine the output command; where τ out is the output command, and τ cmd is the torque command.

6. The robotic arm boundary limitation method according to claim 5, wherein The comparing the desired position command with the robotic arm boundary value to determine the output command includes: If q min ≤ q d ≤ q max , then output the torque command τ cmd ; If q d > q max or q d < q min , then output instruction τ out = τ wall ; where q d is the desired position command, and q target includes the joint maximum boundary q max and the joint minimum boundary q min .

7. The method for limiting the boundary of a robotic arm according to claim 5, wherein The comparing the desired speed command with the real-time feedback speed corresponding to when the robotic arm boundary value is exceeded to determine the output command includes: If the desired velocity command and the sign of the real-time feedback velocity q target corresponding to the value beyond the robotic arm boundary q are different, then output the torque command τ cmd ; If the desired velocity command has the same sign as the real-time feedback velocity q corresponding to the value q that exceeds the manipulator boundary target , then the output command τ out = τ wall .

8. The robotic arm boundary limitation method according to claim 1, characterized in that, The issued command includes a simultaneous limitation mode and a non-simultaneous limitation mode; If it is the simultaneous limitation mode, enable the boundary limiters of all joints; If it is the non-simultaneous limitation mode, only enable the boundary limiters of the joints that exceed the boundary.

9. The method for limiting the boundary of the robotic arm according to claim 4, wherein The calculation formula for the gravity compensation value of the robotic arm is as follows: where τ link is the dynamic torque of the connecting rod, M(q) is the inertia parameter matrix of the robot, is the Coriolis force and centrifugal force term, G(q) is the gravity torque, represents the real-time feedback acceleration of the joint.

10. A robotic arm boundary limit system, characterized in that, The system includes: A motion parameter acquisition module for obtaining real-time motion parameters of each joint of the target robotic arm, where the motion parameters include real-time feedback position; A judgment module for judging whether the real-time feedback position exceeds the robotic arm boundary value. If it exceeds the robotic arm boundary value, enable the boundary limiters of each joint and calculate the command correction value of the boundary limiter; A command output module for obtaining the issued command of the user, and based on the issued command and the command correction value, determining the corresponding output command of the boundary limiter to perform multi-mode limitation on the robotic arm.

11. The robotic arm boundary limitation system according to claim 10, characterized in that, The judgment module includes a command correction value calculation unit for calculating the command correction value of the boundary limiter, and the calculation formula is as follows:

12. The robotic arm boundary limit system according to claim 10, characterized in that, The command output module further includes: A current command unit for converting the command correction value into current and outputting it if the issued command is a current command; Torque command unit, if the issued command only has a torque command, the output command is: τ out = τ cmd + τ wall ; A first mixed command unit for comparing the desired position command with the robotic arm boundary value to determine the output command if the issued command is a torque and desired position command; A second mixed command unit for comparing the desired speed command with the real-time feedback speed corresponding to when the robotic arm boundary value is exceeded to determine the output command if the issued command is a torque and desired speed command.

13. The robotic arm boundary limit system according to claim 12, wherein, The first mixing instruction unit is used for: If q min ≤ q d ≤ q max , then output the torque command τ cmd ; If q d > q max or q d < q min , then output instruction τ out = τ wall .

14. The robotic arm boundary limit system according to claim 12, wherein The second mixing instruction unit is used for: If the desired velocity command and the sign of the real-time feedback velocity q target corresponding to beyond the robotic arm boundary value q are different, then output the torque command τ cmd ; If the desired velocity command has the same sign as the real-time feedback velocity q corresponding to the value q exceeding the manipulator boundary target , then output the command τ out = τ wall .

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