Six-axis robot operation control method and device, six-axis robot, and storage medium

Abstract

This invention proposes a six-axis robot operation control method, device, six-axis robot, and storage medium, relating to the field of robot control technology. The method employs a decoupled hybrid interpolation strategy when the end effector is detected to be traversing a singular region. This strategy involves independently planning the joint motions affecting the posture and combining them with position interpolation. This avoids the joint overspeed, overcurrent, and motion loss-of-control problems caused by traditional pose-based joint interpolation methods near singular points. While ensuring the end effector always moves strictly along the target straight trajectory, it reasonably sacrifices minor posture deviations, improving the robot's motion stability and system robustness when traversing singular regions. This enables continuous and controllable output of joint commands, thereby ensuring equipment safety and process quality, and has significant engineering application value.

Description

Technical Field

[0001] This invention relates to the field of robot control technology, and more specifically, to a six-axis robot operation control method, device, six-axis robot, and storage medium. Background Technology

[0002] With the continuous improvement of industrial automation, six-axis serial articulated robots have been widely used in manufacturing scenarios such as welding, assembly, painting, and material handling due to their high flexibility and large workspace. In actual operations, to ensure processing quality and process consistency, the robot's end effector is often required to move precisely along a predetermined straight trajectory (such as point-to-point linear interpolation). Such tasks typically involve a controller discretizing the target path to generate a series of interpolation points, and then using inverse kinematics algorithms to convert the Cartesian space pose of each interpolation point into joint space commands, thereby driving the servo system to complete motion control.

[0003] However, a special type of configuration exists in robot kinematics—singular configurations. When a robot approaches or is in this configuration, its Jacobian matrix loses its full-rank property, leading to a degradation or even unsolvable mapping relationship from end-effector velocity to joint velocity. Common singular regions include wrist singularities (e.g., the 4th and 6th axes are collinear), shoulder singularities (the 1st–3rd axes are coplanar), and elbow singularities. Once the trajectory crosses these regions, conventional inverse kinematics solutions are highly susceptible to problems such as abrupt joint angle changes, joint overspeed, and increased vibration, which can lead to motion interruption or equipment damage in severe cases. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a six-axis robot operation control method, apparatus, six-axis robot, and computer-readable storage medium.

[0005] To achieve the above objectives, the technical solutions adopted in the embodiments of the present invention are as follows:

[0006] In a first aspect, the present invention provides a six-axis robot operation control method, which utilizes a controller for a six-axis robot, the method comprising:

[0007] After receiving a motion command instructing the end effector of the six-axis robot to move from the starting point to the ending point along the target straight trajectory, the joint space state information and end effector spatial pose information corresponding to the starting point and the ending point are obtained.

[0008] If, based on the joint space state information and end-effector spatial pose information corresponding to the starting point and the ending point, it is determined that the end-effector of the six-axis robot will pass through a pre-defined type of singular region during its movement from the starting point to the ending point, then motion planning is performed on the joint groups affecting the end-effector posture using a first pre-defined strategy to obtain the posture-related joint parameters of the end-effector of the six-axis robot at each interpolation point, wherein the interpolation point is obtained by discretizing the target straight-line trajectory;

[0009] The end effector of the six-axis robot is interpolated in a preset coordinate system using a second preset strategy to obtain the ideal position parameters of the end effector at each interpolation point.

[0010] Based on the ideal position parameters and attitude-related joint parameters of the end effector of the six-axis robot at each interpolation point, a joint command sequence is generated;

[0011] The joint command sequence is output to the servo drive system of the six-axis robot so that the end effector of the six-axis robot smoothly traverses the strange region along the target straight line trajectory.

[0012] Optionally, the step of determining, based on the joint space state information and end-effector spatial pose information corresponding to the starting point and the ending point, that the end-effector of the six-axis robot will pass through a pre-defined type of singular region during its movement from the starting point to the ending point includes:

[0013] Based on the joint space state information corresponding to the starting point and the ending point, if it is determined that the target straight trajectory crosses a singular region of a preset category, the target straight trajectory is discretized to obtain multiple candidate interpolation points.

[0014] For each candidate interpolation point, position linear interpolation and attitude interpolation are performed based on the end-effector space pose information of the starting point and the ending point to obtain the target pose of the candidate interpolation point;

[0015] Based on the target pose, the six-axis joint angles of the six-axis robot corresponding to the candidate interpolation point are calculated.

[0016] If the absolute value of the fifth axis joint angle in the six-axis joint angles is less than the first preset angle threshold, then the candidate interpolation point is determined to meet the preset condition.

[0017] If at least one of the candidate interpolation points satisfies the preset conditions, it is determined that the end effector of the six-axis robot will pass through a pre-defined type of singular region during its movement from the starting point to the ending point.

[0018] Optionally, the step of determining that the target straight-line trajectory crosses a pre-defined category of singular regions based on the joint space state information corresponding to the starting point and the ending point includes:

[0019] Extract the fifth-axis joint angle corresponding to the starting point and the fifth-axis joint angle corresponding to the ending point from the joint space state information corresponding to the starting point and the ending point;

[0020] If the sign of the fifth axis joint angle corresponding to the starting point is opposite to the sign of the fifth axis joint angle corresponding to the ending point, then the target straight line trajectory is determined to cross a predefined type of singular region.

[0021] Optionally, the joint group affecting the end effector posture is the fourth to sixth axes of the six-axis robot. The step of performing motion planning on the joint group affecting the end effector posture using a first preset strategy to obtain the posture-related joint parameters of the six-axis robot's end effector at each interpolation point includes:

[0022] Based on the end-effector spatial pose information corresponding to the starting point and the ending point, the inverse kinematics solutions of the fourth to sixth axes of the six-axis robot are solved to obtain the attitude-related joint parameters of the end-effector of the six-axis robot at each interpolation point.

[0023] Optionally, the step of interpolating the position of the end effector of the six-axis robot in a preset coordinate system using a second preset strategy to obtain the ideal position parameters of the end effector of the six-axis robot at each interpolation point includes:

[0024] Under the preset coordinate system, based on the spatial position coordinates of the starting point and the spatial position coordinates of the ending point, the ideal position coordinates of the end of the six-axis robot at each interpolation point are obtained;

[0025] The ideal position coordinates of the end effector of the six-axis robot at each interpolation point are used as the ideal position parameters of the end effector of the six-axis robot at each interpolation point.

[0026] Optionally, the step of generating a joint command sequence based on the ideal position parameters and attitude-related joint parameters of each interpolation point at the end of the six-axis robot includes:

[0027] For each interpolation point, inverse kinematics is performed based on the ideal position parameters and attitude-related joint parameters of the end effector of the six-axis robot at the interpolation point to obtain the target angle parameters of each joint of the six-axis robot at the interpolation point.

[0028] The joint command sequence is generated using the target angle parameters of each joint of the six-axis robot at each interpolation point.

[0029] Optionally, the step of generating the joint command sequence using the target angle parameters of each joint of the six-axis robot at each interpolation point includes:

[0030] The target angle parameters of each joint of the six-axis robot at each interpolation point are processed by time parameterization to generate the joint command sequence containing target position, velocity and acceleration information.

[0031] Secondly, the present invention provides a six-axis robot operation control device, which utilizes a controller for a six-axis robot, the device comprising:

[0032] The acquisition module is used to acquire the joint space state information and end-effector spatial pose information corresponding to the starting point and the ending point after receiving a motion command instructing the end of the six-axis robot to move along the target straight line trajectory from the starting point to the ending point.

[0033] The processing module is configured to: if, based on the joint space state information and end-effector spatial pose information corresponding to the starting point and the ending point, it is determined that the end-effector of the six-axis robot will pass through a pre-defined type of singular region during its movement from the starting point to the ending point; then, perform motion planning on the joint groups affecting the end-effector posture using a first pre-defined strategy to obtain the posture-related joint parameters of the end-effector at each interpolation point, wherein the interpolation point is obtained by discretizing the target straight-line trajectory; perform position interpolation on the end-effector of the six-axis robot in a pre-defined coordinate system using a second pre-defined strategy to obtain the ideal position parameters of the end-effector at each interpolation point; and generate a joint command sequence based on the ideal position parameters of the end-effector at each interpolation point and the posture-related joint parameters.

[0034] The output module is used to output the joint command sequence to the servo drive system of the six-axis robot, so that the end effector of the six-axis robot can smoothly traverse the strange region along the target straight line trajectory.

[0035] Thirdly, the present invention provides a six-axis robot, including a controller and a memory, wherein the memory stores machine-executable instructions that can be executed by the processor, and the controller can execute the machine-executable instructions to implement the six-axis robot operation control method described in the first aspect above.

[0036] Fourthly, the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the six-axis robot operation control method described in the first aspect above.

[0037] The six-axis robot operation control method, device, six-axis robot, and storage medium provided in this invention are as follows: After receiving a motion command instructing the end effector of the six-axis robot to move along a target straight trajectory from a starting point to an ending point, the method acquires the joint space state information and end effector spatial pose information corresponding to the starting point and the ending point. If, based on the joint space state information and end effector spatial pose information corresponding to the starting point and the ending point, it is determined that the end effector of the six-axis robot will pass through a pre-defined type of singular region during its movement from the starting point to the ending point, a first pre-defined strategy is used to perform motion planning on the joint groups affecting the end effector's posture, obtaining the posture-related joint parameters of the end effector of the six-axis robot at each interpolation point. The interpolation points are obtained by discretizing the target straight trajectory. A second pre-defined strategy is used to perform position interpolation on the end effector of the six-axis robot in a pre-defined coordinate system, obtaining the ideal position parameters of the end effector of the six-axis robot at each interpolation point. Based on the ideal position parameters of the end effector of the six-axis robot at each interpolation point and the posture-related joint parameters, a joint command sequence is generated. The joint command sequence is output to the servo drive system of the six-axis robot so that the end effector of the six-axis robot can smoothly traverse the singular region along the target straight trajectory. Because the embodiments of the present invention employ a decoupled hybrid interpolation strategy when the end effector is detected to be traversing a singular region—that is, independently planning the joint group motions that affect the posture and combining them with position interpolation—it avoids the problems of joint overspeed, overcurrent, and motion loss of control caused by traditional pose joint interpolation methods near singular points. While ensuring that the end effector always moves strictly along the target straight trajectory, it reasonably sacrifices small posture deviations, improves the motion stability and system robustness of the robot when traversing singular regions, and realizes continuous and controllable output of joint commands, thereby ensuring equipment safety and process quality, and has good engineering application value.

[0038] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0039] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 A simplified structural diagram of a six-axis robot provided by an embodiment of the present invention is shown;

[0041] Figure 2 This diagram illustrates a standard DH parameter modeling schematic of a six-axis spherical wrist robot provided by an embodiment of the present invention.

[0042] Figure 3 This diagram illustrates the absolute position of a six-axis spherical wrist robot provided in an embodiment of the present invention under conditions without verticality error compensation.

[0043] Figure 4 A flowchart illustrating a six-axis robot operation control method provided by an embodiment of the present invention is shown;

[0044] Figure 5 An example diagram of the trend curve of attitude deviation as a function of interpolation points over the entire trajectory, provided by an embodiment of the present invention, is shown.

[0045] Figure 6 An example diagram of the velocity response curves of each joint during motion, provided by an embodiment of the present invention, is shown.

[0046] Figure 7 The diagram shows a functional block diagram of a six-axis robot operation control device provided in an embodiment of the present invention.

[0047] Icons: 100-Six-axis robot; 110-Memory; 120-Controller; 200-Six-axis robot operation control device; 201-Acquisition module; 202-Processing module; 203-Output module. Detailed Implementation

[0048] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0049] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0050] It should be noted that relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0051] In current industrial robot control systems, six-axis serial robots have become core execution units in automated production due to their excellent flexibility and wide range of applications. To achieve precise spatial trajectory control, Cartesian linear motion interpolation algorithms are typically used to enable the robot's end effector to move smoothly from the starting point to the ending point along a preset straight path. Traditional linear motion interpolation methods generally employ a two-step strategy of "position-attitude interpolation + standard inverse kinematics solution": firstly, based on the pose information of the starting and ending points, linear interpolation is performed on the position and attitude of the end effector in Cartesian space to obtain a series of target poses at intermediate interpolation points; then, for each interpolation point, the standard inverse kinematics algorithm is called to calculate the corresponding joint angle commands and generate the corresponding joint drive sequence.

[0052] However, this traditional interpolation method has significant drawbacks when dealing with singular regions in robot kinematics. For a typical six-axis spherical wrist robot, the singularity mainly manifests in three situations: (1) the rotation axes of the fourth, fifth, and sixth axes intersect at a point and are located on the first axis (the wrist center falls on the vertical axis of the base); (2) the second and third axes are collinear, causing the shoulder to straighten; (3) the joint angle of the fifth axis is close to zero degrees or ±180°, making the fourth and sixth axes tend to be coaxial, resulting in a rank deficiency in the Jacobian matrix, and the system loses its ability to control movement in a certain direction. Among these, the first two types of singular configurations can be avoided by rationally planning the working path, while the third type—the wrist singularity problem caused by the excessively small angle of the fifth axis—is difficult to completely avoid in practical applications, especially in situations where the end effector needs to perform precise operations in the vertical direction.

[0053] When a robot traverses such unusual regions, using traditional pose interpolation methods can lead to extremely high instantaneous velocities, even approaching infinity, in higher-order joints (especially the fourth axis) during inverse kinematics. This can exceed the servo system's maximum speed limit or current carrying capacity, triggering overspeed and overcurrent protection alarms. In severe cases, this can damage the mechanical structure or endanger personnel safety. Furthermore, the increased numerical instability can cause joint angle jumps or unexpected movements, resulting in trajectory deviations, increased vibration, and other problems, seriously affecting machining accuracy and operational reliability.

[0054] More importantly, in most practical applications, users require far greater accuracy in the robot's end-effector trajectory than strict adherence to its posture. For example, in tasks such as welding, painting, and material handling, it is sufficient to ensure that the tool center point (TCP) travels accurately along a designated straight line, allowing for moderate variations in the end-effector's posture within a certain range to achieve higher motion stability. Therefore, forcibly maintaining a linear posture transition is not only unnecessary but also becomes the technical root cause of control instability.

[0055] In summary, while existing linear motion control methods based on complete pose interpolation are suitable for routine motion in non-singular regions, they exhibit significant limitations and insufficient adaptability when approaching or traversing the singular region of the fifth axis. How to reasonably relax the strong constraints on posture while ensuring the end effector position strictly follows the target linear trajectory, and effectively avoid the risk of joint overshooting through reconstructed interpolation strategies, has become a key technical challenge that urgently needs to be addressed to improve the motion stability and safety of six-axis robots under complex working conditions.

[0056] To address the problems of joint overspeed, overcurrent alarms, and loss of motion control that occur when robots traverse the singular region of the wrist near zero degrees on the fifth axis in existing technologies, embodiments of the present invention provide a six-axis robot operation control method, device, six-axis robot, and storage medium.

[0057] Please refer to Figure 1 This is a block diagram of a six-axis robot 100. The six-axis robot 100 includes a memory 110 and a controller 120. The components of the memory 110 and the controller 120 are directly or indirectly electrically connected to each other to realize data transmission or interaction. For example, these components can be electrically connected to each other through one or more communication buses or signal lines.

[0058] The memory 110 is used to store programs or data. The memory 110 may be, but is not limited to, random access memory (RAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), etc.

[0059] The controller 120 is used to read / write data or programs stored in the memory 110 and perform corresponding functions.

[0060] It should be understood that, Figure 1 The structure shown is only a schematic diagram of a six-axis robot 100. The server may also include components that are larger than... Figure 1 The more or fewer components shown, or having the same Figure 1 The different configurations shown. Figure 1 The components shown can be implemented using hardware, software, or a combination thereof.

[0061] To achieve accurate solution of the end-effector pose and inverse kinematics calculation for a six-axis robot, this embodiment of the invention establishes the robot's forward kinematics model based on the standard Denavit-Hartenberg (DH) method.

[0062] Figure 2 This is a schematic diagram illustrating the standard DH parameter modeling of the six-axis spherical wrist robot described in this embodiment of the invention. The kinematic model of the robot is established using the standard DH method, yielding the DH parameters for each joint: , , ,in The process is as follows:

[0063] Firstly in Establish a joint coordinate system at each joint axis. Joint coordinate system of shaft, shaft , The method for constructing an axis is as follows:

[0064] : No. The joint axes, in the positive direction, satisfy the right-hand screw rule;

[0065] : No. Joint axis and The common perpendicular line of the axes of the nth joint, with the positive direction starting from the nth joint axis. The axis of each joint points to One joint axis;

[0066] : Cross product .

[0067] Then determine the first The DH parameters of the nth joint, the nth The meanings of the DH parameters for each joint are as follows:

[0068] : Linkage offset angle, indicating that... Along The shaft rotates to Angle;

[0069] Linkage offset indicates that the link will be offset. Along axis translation to The distance;

[0070] : Link length, indicating the length of the link. Along axis translation to The distance;

[0071] : Linkage torsion angle, indicating the... Along The shaft rotates to The angle.

[0072] The DH parameters of each joint of the robot are shown in the table below:

[0073]

[0074] In the table , , , , , All are known to be non-zero constants.

[0075] Based on the coordinate system relationship of each link established by the aforementioned DH parameters, this embodiment of the invention further constructs a forward kinematics model of the robot, which is used to map from the joint space perspective to the pose of the end effector in Cartesian space.

[0076] like Figure 3As shown, the robot's base coordinate system coincides with the joint coordinate system of the first axis. In the The joint axis coordinate system of the axis is The robot end-effector coordinate system is The coordinate system of the fourth axis can be obtained by using coordinate transformation methods. To the end tool coordinate system Homogeneous transformation matrix:

[0077]

[0078] in, Indicates from the joint coordinate system To the joint coordinate system The homogeneous transformation matrix, , The calculation formula is as follows:

[0079]

[0080] Indicates the first Angle of each joint , , , The value is described in the aforementioned DH parameter.

[0081] Indicates from the joint coordinate system To the end tool coordinate system The homogeneous transformation matrix, whose positional part has been obtained using a 5-point or multi-point calibration method. , , All are known.

[0082]

[0083] Next, based on the aforementioned DH parameters and forward kinematics model of the robot, the six-axis robot operation control method provided in this embodiment of the invention will be introduced.

[0084] Please refer to Figure 4 The six-axis robot operation control method includes steps S101 to S105.

[0085] S101, after receiving a motion command instructing the end effector of the six-axis robot to move from the starting point to the ending point along the target straight line trajectory, acquire the joint space state information and end effector spatial pose information corresponding to the starting point and the ending point.

[0086] When the controller of a six-axis robot receives a motion command instructing its end effector to move from the starting point to the ending point along a target straight line trajectory, it first parses the command content and obtains two types of core state information related to the starting point and the ending point: joint space state information and end effector tool space pose information.

[0087] The joint space state information includes the starting point. Corresponding joint coordinates and the end point Corresponding joint coordinates , and It is a 6-dimensional vector. , .

[0088] End-effector spatial pose information includes the origin. Homogeneous transformation matrix from base coordinate system to tool coordinate system , , , It is a 3-dimensional vector, representing the homogeneous transformation matrix. The location part.

[0089] Also includes the endpoint Homogeneous transformation matrix from base coordinate system to tool coordinate system , , These are 3-dimensional vectors, each representing a homogeneous transformation matrix. The location part.

[0090] S102, if based on the joint space state information and end tool space pose information corresponding to the start and end points, it is determined that the end of the six-axis robot will pass through a pre-defined type of singular region during the process of moving from the start point to the end point, then the motion planning of the joint group affecting the end pose is performed through the first pre-defined strategy to obtain the attitude-related joint parameters of the end of the six-axis robot at each interpolation point.

[0091] The interpolation points are obtained by discretizing the target straight-line trajectory.

[0092] After obtaining the state information of the starting point and the ending point, it is necessary to determine whether the robot will cross a certain type of singularity region during its movement from the starting point to the ending point (which could be a wrist singularity caused by the fifth axis joint angle theta_5 being close to 0° or ±180°). If the determination result is "yes", the hybrid interpolation strategy is activated; otherwise, the conventional position-attitude interpolation method can be used.

[0093] In order to accurately identify whether there is a singular crossing risk, this embodiment of the invention proposes a singular crossing detection mechanism based on joint space state criteria, including steps S201 to S205.

[0094] S201, based on the joint space state information corresponding to the starting point and the ending point, if it is determined that the target straight line trajectory crosses a singular region of a preset category, the target straight line trajectory is discretized to obtain multiple candidate interpolation points.

[0095] The implementation process of "determining the singular region of the target straight line trajectory that crosses a preset category based on the joint space state information corresponding to the start and end points" can be as follows: extract the fifth axis joint angle corresponding to the start point and the fifth axis joint angle corresponding to the end point from the joint space state information corresponding to the start and end points; if the sign of the fifth axis joint angle corresponding to the start point is opposite to the sign of the fifth axis joint angle corresponding to the end point, then it is determined that the target straight line trajectory crosses a singular region of a preset category.

[0096] In other words, from the joint space state information corresponding to the start and end points input by the user, the fifth axis joint angle theta_5_star corresponding to the start point and the fifth axis joint angle theta_5_end corresponding to the end point are extracted.

[0097] If the signs of theta_5_star and theta_5_end are opposite, it indicates that the robot may pass through a near-zero angle on the fifth axis during its movement, posing a risk of traversing a singular configuration at the wrist. This determines that the target straight-line trajectory crosses a pre-defined singular region, triggering subsequent trajectory refinement detection. Conversely, if the signs of theta_5_star and theta_5_end are the same, it is determined that the movement process does not involve significant singular risks, and trajectory planning can be directly performed using traditional pose interpolation methods without needing to enable a hybrid interpolation control strategy.

[0098] After determining that the target straight-line trajectory crosses a singular region of a preset category, the target straight-line trajectory is constructed based on the spatial coordinates of the starting and ending points. The trajectory is then discretized according to a preset time step or spatial distance step to obtain a series of candidate interpolation points uniformly distributed along the straight line. Each candidate interpolation point corresponds to a spatial configuration to be evaluated.

[0099] S202, for each candidate interpolation point, perform position linear interpolation and attitude interpolation based on the end-effector spatial pose information of the start and end points to obtain the target pose of the candidate interpolation point.

[0100] For each candidate interpolation point, based on the end-effector spatial pose information of the start and end points, position linear interpolation and attitude interpolation are performed to obtain the target pose of that point, including:

[0101] In terms of location, a linear interpolation method is used to calculate the target location of the interpolation points;

[0102] In the attitude dimension, the target rotation matrix of the interpolation point is calculated using spherical linear interpolation (SLERP) or other continuous attitude interpolation methods;

[0103] The above position and attitude are combined into a complete homogeneous transformation matrix, which is taken as the target pose of the interpolation point. S203, based on the target pose, the six-axis joint angles of the six-axis robot corresponding to the candidate interpolation point are calculated.

[0104] The standard inverse kinematics algorithm is invoked to solve for the corresponding six-axis robot joint angles, including the joint angles of each axis from the first to the sixth axis, based on the target pose of the candidate interpolation point and the robot's DH parameter model.

[0105] S204, if the absolute value of the fifth axis joint angle in the six-axis joint angle is less than the first preset angle threshold, then the candidate interpolation point is determined to meet the preset condition.

[0106] In other words, for each candidate interpolation point, the absolute value of the fifth axis joint angle is checked to see if it is less than the first preset angle threshold (e.g., it can be set to 5°, 3° or 1°, depending on the actual application scenario).

[0107] If the absolute value of the fifth axis joint angle is less than the first preset angle threshold, then the interpolation point is considered to be in or close to a wrist singular configuration, satisfying the preset condition.

[0108] S205, if there is at least one candidate interpolation point that satisfies the preset conditions, then it is determined that the end effector of the six-axis robot will pass through a pre-defined type of singular region during its movement from the starting point to the ending point.

[0109] Furthermore, if at least one of the candidate interpolation points meets the preset condition, it is determined that the end effector of the six-axis robot will pass through a pre-defined type of singular region during its movement from the starting point to the ending point, and the hybrid interpolation singularity control strategy proposed in this embodiment of the invention needs to be activated; otherwise, if none of the interpolation points meet the condition, it is considered that there is no significant risk of singularity crossing, and the traditional interpolation method can continue to be used to complete the trajectory execution.

[0110] The joint groups affecting the end effector posture are the fourth to sixth axes of the six-axis robot. Further, the implementation process of "performing motion planning on the joint groups affecting the end effector posture through the first preset strategy to obtain the posture-related joint parameters of the end effector of the six-axis robot at each interpolation point" in step S102 can be as follows: based on the end effector tool space pose information corresponding to the starting point and the ending point, solve the inverse kinematics solution of the fourth to sixth axes of the six-axis robot to obtain the posture-related joint parameters of the end effector of the six-axis robot at each interpolation point.

[0111] In other words, by using the complete end-effector spatial pose information at the start and end points, a standard inverse kinematics solution is performed to obtain the six-axis joint angles corresponding to the start and end points.

[0112] Based on this, the joint angles of the fourth to sixth axes at the start and end points are extracted and recorded as the start-point attitude-related parameters and the end-point attitude-related parameters.

[0113] During trajectory interpolation, for any interpolation point, its attitude-related joint parameters (joint angles from the fourth to the sixth axis) can be obtained by performing joint space linear interpolation on the corresponding joint angles at the starting and ending points.

[0114] Next, the remaining steps of the six-axis robot operation control method provided in the embodiments of the present invention will be described in detail.

[0115] S103, the end effector of the six-axis robot is interpolated in a preset coordinate system using a second preset strategy to obtain the ideal position parameters of the end effector of the six-axis robot at each interpolation point.

[0116] After planning the attitude-related joint parameters, the position of the end effector in the preset coordinate system (usually the base coordinate system) is independently interpolated to obtain the ideal position parameters of each interpolation point.

[0117] In a possible implementation, step S103 may include sub-steps S103-1 to S103-2.

[0118] S103-1, Under the preset coordinate system, based on the spatial position coordinates of the starting point and the spatial position coordinates of the ending point, obtain the ideal position coordinates of the end effector of the six-axis robot at each interpolation point.

[0119] The target straight-line trajectory is discretized according to time or distance steps to obtain an interpolation point sequence. For each interpolation point, its ideal position coordinates are obtained by linear interpolation of the starting and ending positions.

[0120] S103-2, the ideal position coordinates of the end effector of the six-axis robot at each interpolation point are used as the ideal position parameters of the end effector of the six-axis robot at each interpolation point.

[0121] S104 generates a joint command sequence based on the ideal position parameters and attitude-related joint parameters of the end effector of the six-axis robot at each interpolation point.

[0122] In a possible implementation, step S104 may include sub-steps S104-1 to S104-2.

[0123] S104-1, For each interpolation point, based on the ideal position parameters and attitude-related joint parameters of the end effector of the six-axis robot at the interpolation point, inverse kinematics is solved to obtain the target angle parameters of each joint of the six-axis robot at the interpolation point.

[0124] For each interpolation point, using the known ideal position and the joint angles of the fourth to sixth axes, combined with the robot's DH parameter model and forward kinematics model, the values ​​of the joint angles of the first three joints are deduced to ensure accurate matching of the actual position of the end effector.

[0125] This process is a constrained inverse problem, typically with multiple feasible solutions (e.g., left / right arm, elbow-above / elbow-below, flipped / non-flipped configurations). A unique solution can be selected based on user-defined axis configuration flags, ensuring the continuity and consistency of the motion path.

[0126] Thus, a complete six-dimensional joint angle vector is obtained, which serves as the target angle parameter for the interpolation point.

[0127] S104-2, using the target angle parameters of each joint of the six-axis robot at each interpolation point, generate a joint command sequence.

[0128] In this embodiment of the invention, the target angle parameters of each joint of a six-axis robot at each interpolation point can be time-parameterized to generate a joint command sequence containing target position, velocity, and acceleration information.

[0129] In other words, the target angle parameters of all interpolation points are arranged in chronological order to form a preliminary joint angle sequence. Based on the maximum allowable speed and acceleration limits of each axis (such as 300° / s, 500° / s²), the angle sequence is remapped in time to generate a complete joint command sequence containing target position, speed, and acceleration information for the servo system to track in real time.

[0130] Understandably, the above hybrid interpolation mechanism is based on the fourth to sixth axes corresponding to the start and end points (denoted as...). , , The coordinates are obtained by performing joint linear interpolation on the joint coordinates. , , Substituting into the formula, we get The position part is then obtained by linear interpolation based on the positions of the starting point and the target point. ,according to , , and Combining the robot's DH parameters, the inverse solution is obtained. , , joint angle , , It includes the following implementation parts:

[0131] (1) , , Joint linear interpolation:

[0132] Define step size for and The ratio is a known input value:

[0133]

[0134] (2) Find Location:

[0135] Formula wrist joint coordinates obtained from the middle , , Combined with the aforementioned DH parameters , , Substitute into the formula From , , and in combination with formula Substitute into the formula By simplifying the equations, we obtain... The values ​​are as follows:

[0136]

[0137] (3) Linear interpolation of the end position:

[0138] Linear interpolation of the end position and the start position Corresponding joint coordinates ,end Corresponding joint coordinates ,starting point Homogeneous transformation matrix from base coordinate system to tool coordinate system and the finish line Substituting the homogeneous transformation matrix from the base coordinate system to the tool coordinate system, we get:

[0139]

[0140]

[0141] (4) Solve for the first axis (denoted as) Joint angles:

[0142] For the end position obtained by the above linear interpolation Robot wrist joint coordinates , , Given the given information, use the inverse solution to find the first to third axes (denoted as ). , , The joint angles of a given point typically have four analytical solutions, configured via the input axis. To determine which solution the robot should choose. The expression is defined as follows:

[0143]

[0144] express The configuration of the shaft joint determines Similarly, the joint angle values ​​of the axis are determined. Decide separately The value of the joint angle is related to... , , Intersection of joint axes Related, where elements are defined:

[0145] ,

[0146] Desired configuration The values ​​of each element are obtained through user input. Given:

[0147]

[0148] in , and The value in finding The location has already been obtained. The value in , , This was obtained during joint linear interpolation.

[0149] (5) Solve Joint angle:

[0150] The joint angles satisfy the following formula:

[0151]

[0152] in, , , , .

[0153] (6) Solve Joint angle:

[0154] The joint angles satisfy the following formula:

[0155]

[0156] S105 outputs the joint command sequence to the servo drive system of the six-axis robot so that the end effector of the six-axis robot can smoothly traverse the strange region along the target straight trajectory.

[0157] Experimental verification shows (see) Figure 5 and Figure 6 After adopting the six-axis robot operation control method provided in the embodiments of the present invention, the robot end effector always stays on the target straight line throughout the entire movement process (position error is controllable), and although there is a certain deviation in the posture in the middle section (the maximum is about 4.63°), it is still within the range allowed by most processes; more importantly, the speed of each joint (especially the fourth axis) is always within the safety limit, and there is no overspeed or overcurrent phenomenon, realizing the smooth passage through the strange region.

[0158] In summary, the embodiments of the present invention, through the decoupling design of position and attitude interpolation paths and based on the inverse control architecture of "joint position hybrid interpolation", meet the requirements of high-precision trajectory tracking.

[0159] To perform the corresponding steps in the above embodiments and various possible methods, an implementation of a six-axis robot operation control device 200 is given below. Further, please refer to... Figure 7 , Figure 7 This is a functional block diagram of a six-axis robot operation control device 200 provided in an embodiment of the present invention. It should be noted that the basic principle and technical effects of the six-axis robot operation control device 200 provided in this embodiment are the same as those in the above embodiments. For the sake of brevity, any parts not mentioned in this embodiment can be referred to the corresponding content in the above embodiments. The six-axis robot operation control device 200 includes:

[0160] The acquisition module 201 is used to acquire the joint space state information and end tool space pose information corresponding to the starting point and the ending point after receiving a motion command that instructs the end of the six-axis robot to move from the starting point to the ending point along the target straight line trajectory.

[0161] The processing module 202 is used to perform motion planning on the joint groups affecting the end-effector's posture using a first preset strategy if it is determined that the end-effector of the six-axis robot will pass through a preset type of singular region during its movement from the start point to the end point, based on the joint space state information and end-effector pose information corresponding to the start and end points. This yields the posture-related joint parameters of the end-effector at each interpolation point, where the interpolation point is obtained by discretizing the target straight-line trajectory. The module also performs position interpolation on the end-effector of the six-axis robot in a preset coordinate system using a second preset strategy to obtain the ideal position parameters of the end-effector at each interpolation point. Based on the ideal position parameters of the end-effector at each interpolation point and the posture-related joint parameters, the module generates a joint command sequence.

[0162] Output module 203 is used to output the joint command sequence to the servo drive system of the six-axis robot so that the end effector of the six-axis robot can smoothly pass through the strange region along the target straight line trajectory.

[0163] Optionally, the above modules can be stored in the form of software or firmware. Figure 1 The memory 110 shown can be used by Figure 1 The controller 120 in the memory executes the commands. Meanwhile, the data and program code required to execute the above modules can be stored in the memory 110.

[0164] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can also be implemented in other ways. The apparatus embodiments described above are merely illustrative; for example, the flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of apparatus, methods, and computer program products according to various embodiments of the present invention. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than those marked in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram and / or flowchart, and combinations of blocks in block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

[0165] In addition, the functional modules in the various embodiments of the present invention can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0166] If the aforementioned functions are implemented as software functional modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0167] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A six-axis robot operation control method characterized by, The method, which utilizes a controller for a six-axis robot, includes: After receiving a motion command instructing the end effector of the six-axis robot to move from the starting point to the ending point along the target straight trajectory, the joint space state information and the end effector spatial pose information corresponding to the starting point and the ending point are obtained. If, based on the joint space state information and end-effector spatial pose information corresponding to the starting point and the ending point, it is determined that the end-effector of the six-axis robot will pass through a pre-defined type of singular region during its movement from the starting point to the ending point, then motion planning is performed on the joint groups affecting the end-effector posture using a first pre-defined strategy to obtain the posture-related joint parameters of the end-effector of the six-axis robot at each interpolation point, wherein the interpolation point is obtained by discretizing the target straight-line trajectory; The end effector of the six-axis robot is interpolated in a preset coordinate system using a second preset strategy to obtain the ideal position parameters of the end effector at each interpolation point. Based on the ideal position parameters and attitude-related joint parameters of the end effector of the six-axis robot at each interpolation point, a joint command sequence is generated; The joint command sequence is output to the servo drive system of the six-axis robot so that the end effector of the six-axis robot smoothly traverses the strange region along the target straight line trajectory.

2. The six-axis robot operation control method as described in claim 1, characterized in that, The step of determining, based on the joint space state information and end-effector spatial pose information corresponding to the starting point and the ending point, that the end-effector of the six-axis robot will pass through a pre-defined type of singular region during its movement from the starting point to the ending point includes: Based on the joint space state information corresponding to the starting point and the ending point, if it is determined that the target straight trajectory crosses a singular region of a preset category, the target straight trajectory is discretized to obtain multiple candidate interpolation points. For each candidate interpolation point, position linear interpolation and attitude interpolation are performed based on the end-effector space pose information of the starting point and the ending point to obtain the target pose of the candidate interpolation point; Based on the target pose, the six-axis joint angles of the six-axis robot corresponding to the candidate interpolation point are calculated. If the absolute value of the fifth axis joint angle in the six-axis joint angles is less than the first preset angle threshold, then the candidate interpolation point is determined to meet the preset condition. If at least one of the candidate interpolation points satisfies the preset conditions, it is determined that the end effector of the six-axis robot will pass through a pre-defined type of singular region during its movement from the starting point to the ending point.

3. The six-axis robot operation control method as described in claim 2, characterized in that, The step of determining that the target straight-line trajectory crosses a pre-defined category of singular regions based on the joint space state information corresponding to the starting point and the ending point includes: Extract the fifth-axis joint angle corresponding to the starting point and the fifth-axis joint angle corresponding to the ending point from the joint space state information corresponding to the starting point and the ending point; If the sign of the fifth axis joint angle corresponding to the starting point is opposite to the sign of the fifth axis joint angle corresponding to the ending point, then the target straight line trajectory is determined to cross a predefined type of singular region.

4. The six-axis robot operation control method as described in claim 1, characterized in that, The joint groups affecting the end-effector posture are the fourth to sixth axes of the six-axis robot. The step of performing motion planning on the joint groups affecting the end-effector posture using a first preset strategy to obtain the posture-related joint parameters of the six-axis robot's end-effector at each interpolation point includes: Based on the end-effector spatial pose information corresponding to the starting point and the ending point, the inverse kinematics solutions of the fourth to sixth axes of the six-axis robot are solved to obtain the attitude-related joint parameters of the end-effector of the six-axis robot at each interpolation point.

5. The six-axis robot operation control method as described in claim 1, characterized in that, The step of interpolating the position of the end effector of the six-axis robot in a preset coordinate system using a second preset strategy to obtain the ideal position parameters of the end effector at each interpolation point includes: Under the preset coordinate system, based on the spatial position coordinates of the starting point and the spatial position coordinates of the ending point, the ideal position coordinates of the end of the six-axis robot at each interpolation point are obtained; The ideal position coordinates of the end effector of the six-axis robot at each interpolation point are used as the ideal position parameters of the end effector of the six-axis robot at each interpolation point.

6. The six-axis robot operation control method as described in claim 1, characterized in that, The step of generating a joint command sequence based on the ideal position parameters and attitude-related joint parameters of each interpolation point at the end of the six-axis robot includes: For each interpolation point, inverse kinematics is performed based on the ideal position parameters and attitude-related joint parameters of the end effector of the six-axis robot at the interpolation point to obtain the target angle parameters of each joint of the six-axis robot at the interpolation point. The joint command sequence is generated using the target angle parameters of each joint of the six-axis robot at each interpolation point.

7. The six-axis robot operation control method as described in claim 6, characterized in that, The step of generating the joint command sequence using the target angle parameters of each joint of the six-axis robot at each interpolation point includes: The target angle parameters of each joint of the six-axis robot at each interpolation point are processed by time parameterization to obtain the joint command sequence containing target position, velocity and acceleration information.

8. A six-axis robot operation control device, characterized in that, A controller for a six-axis robot, the device comprising: The acquisition module is used to acquire the joint space state information and end-effector spatial pose information corresponding to the starting point and the ending point after receiving a motion command instructing the end of the six-axis robot to move along the target straight line trajectory from the starting point to the ending point. The processing module is configured to: if, based on the joint space state information and end-effector spatial pose information corresponding to the starting point and the ending point, it is determined that the end-effector of the six-axis robot will pass through a pre-defined type of singular region during its movement from the starting point to the ending point; then, perform motion planning on the joint groups affecting the end-effector posture using a first pre-defined strategy to obtain the posture-related joint parameters of the end-effector at each interpolation point, wherein the interpolation point is obtained by discretizing the target straight-line trajectory; perform position interpolation on the end-effector of the six-axis robot in a pre-defined coordinate system using a second pre-defined strategy to obtain the ideal position parameters of the end-effector at each interpolation point; and generate a joint command sequence based on the ideal position parameters of the end-effector at each interpolation point and the posture-related joint parameters. The output module is used to output the joint command sequence to the servo drive system of the six-axis robot, so that the end effector of the six-axis robot can smoothly traverse the strange region along the target straight line trajectory.

9. A six-axis robot, characterized in that, The system includes a controller and a memory, the memory storing machine-executable instructions that can be executed by the controller, the controller executing the machine-executable instructions to implement the six-axis robot operation control method according to any one of claims 1-7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the six-axis robot operation control method as described in any one of claims 1-7.

Images