CN115922684A - Singular point processing method, device, equipment and medium for six-axis robot - Google Patents

Abstract

The embodiment of the present invention discloses a singular point processing method, device, device and medium for a six-axis robot. The method includes: if it is determined that at least one singular region is included in the pre-planned path, obtaining at least one pre-configured constraint Index; wherein, the constraint index includes at least one of a pose index, a velocity index, and a trajectory deviation index; according to the at least one constraint index, determine at least one traffic strategy and traffic loss value corresponding to each singular area; based on The traffic loss value corresponding to each traffic strategy determines the target traffic strategy, so as to pass through the corresponding singular area based on the target traffic strategy. The technical solution of the embodiment of the present invention can ensure that the robot passes through the singularity point smoothly, while meeting the requirements of the user's original programming trajectory, taking into account the scope of application and versatility of the robot.

Description

Singular point processing method, device, equipment and medium for six-axis robot

technical field

Embodiments of the present invention relate to the technical field of intelligent robots, and in particular, to a method, device, device and medium for singular point processing for a six-axis robot.

Background technique

During the motion of the robot, singular points may appear anywhere in the robot's workspace, resulting in a series of problems that affect task execution and bring great inconvenience to the application of the robot.

In the prior art, when processing the singularity, the method of alarm stop is mainly adopted, that is, when the robot moves to the singularity, it stops working and sends an alarm message to the outside; in addition, the methods that can also be used include Add special tooling (such as a displacement device) at the end of the robot to assist the robot to pass through the singularity, or convert the singularity area of the robot to the joint space for re-planning, so that the robot can pass through the singularity based on joint motion.

However, when the alarm stop method is used, the robot cannot pass through the singularity smoothly; adding special tooling will change the robot structure, reducing the scope of application and versatility of the robot; re-planning the singular area will cause the deviation of the original programmed trajectory. The replanned trajectories are also different at different speeds, which may lead to unexpected results.

Contents of the invention

The invention provides a singular point processing method, device, equipment and medium for a six-axis robot to ensure that the robot passes through the singular point smoothly, while meeting the requirements of the user's original programming trajectory, while taking into account the scope of application and versatility of the robot.

In the first aspect, the embodiment of the present invention provides a singular point avoidance method, which is applied to a six-axis robot, and the method includes:

If it is determined that at least one singular region is included in the pre-planned path, at least one pre-configured constraint index is obtained; wherein the constraint index includes at least one of a pose index, a speed index, and a trajectory deviation index;

Determine at least one traffic strategy and traffic loss value corresponding to each singular area according to the at least one constraint index;

Based on the traffic loss value corresponding to each traffic strategy, a target traffic strategy is determined, so as to pass through the corresponding singular area based on the target traffic strategy.

In the second aspect, the embodiment of the present invention also provides a singular point avoidance device, which is applied to a six-axis robot, and the device includes:

A constraint index acquisition module, configured to acquire at least one pre-configured constraint index if it is determined that the pre-planned path includes at least one singular region; wherein, the constraint index includes at least one of a pose index, a speed index, and a trajectory deviation index one;

A traffic strategy determination module, configured to determine at least one traffic strategy and a traffic loss value corresponding to each singular area according to the at least one constraint index;

The target traffic strategy determining module is configured to determine a target traffic strategy based on the traffic loss value corresponding to each traffic strategy, so as to pass through the corresponding singular area based on the target traffic strategy.

In a third aspect, an embodiment of the present invention also provides an electronic device, the electronic device comprising:

one or more processors;

storage means for storing one or more programs,

When the one or more programs are executed by the one or more processors, the one or more processors are made to implement the singular point avoidance method described in any one of the embodiments of the present invention.

In the fourth aspect, the embodiment of the present invention also provides a storage medium containing computer-executable instructions, the computer-executable instructions are used to execute the singular point as described in any one of the embodiments of the present invention when executed by a computer processor. evasion method.

In the technical solution of the embodiment of the present invention, if it is determined that the pre-planned path includes at least one singular area, at least one pre-configured constraint index is obtained. It can be understood that the subsequent processing process can be more in line with actual needs based on the constraint index; according to at least A constraint index, determining at least one traffic strategy and traffic loss value corresponding to each singular region, further, based on the traffic loss value corresponding to each traffic strategy, determining a target traffic strategy, so as to pass through the corresponding singular region based on the target traffic strategy, Not only can it ensure that the robot passes through the singularity smoothly without adding special tooling to the robot, it also takes into account the scope of application and versatility of the robot. Unexpected results occur when the robot replans the trajectory during the work process.

Description of drawings

In order to illustrate the technical solutions of the exemplary embodiments of the present invention more clearly, the following briefly introduces the drawings used in describing the embodiments. Apparently, the drawings introduced are only the drawings of a part of the embodiments to be described in the present invention, rather than all the drawings. Those of ordinary skill in the art can also obtain the Other attached drawings.

FIG. 1 is a schematic flowchart of a singularity avoidance method provided by Embodiment 1 of the present invention;

FIG. 2 is a schematic flowchart of a singularity avoidance method provided by Embodiment 2 of the present invention;

FIG. 3 is a schematic structural diagram of a six-axis robot provided in Embodiment 2 of the present invention;

Fig. 4 is a schematic diagram of adjusting the pose of the end of the robotic arm of the robot with 2 axes, 3 axes, 4 axes and 6 axes provided by Embodiment 2 of the present invention;

FIG. 5 is a flow chart of a singularity avoidance method provided by Embodiment 3 of the present invention;

FIG. 6 is a structural block diagram of a singular point avoidance device provided by Embodiment 4 of the present invention;

FIG. 7 is a schematic structural diagram of an electronic device provided by Embodiment 5 of the present invention.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, but not to limit the present invention. In addition, it should be noted that, for the convenience of description, only some structures related to the present invention are shown in the drawings but not all structures.

Embodiment one

Fig. 1 is a schematic flow chart of a singular point avoidance method provided by Embodiment 1 of the present invention. This embodiment is applicable to the case where a six-axis robot processes a singular point in the workspace. The circumvention device may be implemented in the form of software and/or hardware, and the hardware may be an electronic device, such as a mobile terminal, a PC or a server.

Before the present disclosure is further described in detail, the six-axis robot involved in the embodiments of the present disclosure and the singular points in the field of robot motion control are described here.

As an automated, programmable, automation device with three or more axes of motion, industrial robots are widely used in manufacturing and production. For example, five-axis joint robots and six-axis joint robots have multiple rotation axes. Each axis of rotation is similar to a human arm. Among them, six-axis robots are used more in the market.

Compared to five-axis robots, six-axis robots have more joints and therefore have a higher "degree of freedom of movement". Specifically, the six-axis robot can use the three basic axes as the main axis to control the body rotation, the movement of the upper arm and the movement of the forearm respectively. Up and down motions as well as circular wrist movements. The six-axis robot is based on the servo motor and the driving device to drive the main axis and the secondary axis of the body to complete a variety of complex tasks. Move to another location.

Although the multiple joints of the six-axis robot enhance the flexibility and adaptability of the robot, in the process of actual work, singularity problems may occur. Specifically, singularity problems may occur during the movement of the robot.

For the robot, the singular point is the configuration that makes the Jacobian matrix in the robot kinematics equation dissatisfied rank, which is caused by the inverse kinematics of the robot. When a robot encounters a singularity, its joints may be commanded to move in an impossible manner, causing the robotic arm to move in unpredictable ways and speeds.

In the actual application process, when the six-axis robot encounters a singularity point in the working process, it may cause many problems such as joint overspeed, servo alarm, and loss of motion trajectory of the robotic arm. In severe cases, it may also endanger the health of the staff around the equipment. Personal safety.

Therefore, the technical solution in the embodiment of the present disclosure provides a solution to the problem that the six-axis robot may encounter a singular point during motion.

As shown in Figure 1, the method specifically includes the following steps:

S110. If it is determined that the pre-planned path includes at least one singular region, acquire at least one pre-configured constraint index.

Among them, the pre-planned path can be the motion trajectory pre-planned by the user for the six-axis robot for this task. For example, the staff can manually write the corresponding program for the robot based on a specific programming language. When the six-axis robot receives the job When the command is given, the program written by the staff can be called and run, so that the robotic arm can perform the task according to the movement trajectory reflected in the program.

According to the above description, when the robot encounters a singularity point during motion, it may enter an abnormal state that causes the mechanical arm to cause joint overspeed, servo alarm, and loss of motion trajectory. This state is the singular state. Based on this, on the motion path of the six-axis robot, the part of the path that makes the robot in a singular state is the singular region. It can be understood that at least one singular point is included in the determined singular region. It should be noted that the determination of the singular area in the robot's motion path can be completed before the robot performs the work task.

In this embodiment, when it is determined that the pre-planned path of the six-axis robot includes at least one singular area, in order for the robot to avoid the singular points in the singular area during subsequent operations, it is also necessary to obtain constraint indicators, wherein, Constraint indicators can be thresholds or value ranges specified by users for specific parameters, including at least one of pose indicators, velocity indicators, and trajectory deviation indicators. In actual applications, in order to simplify the user's operation process, you can also set the default Information (that is, directly specifying the threshold or value range of a specific parameter) is used as a constraint indicator. When the robot obtains the constraint index, it indicates that the robot needs to take the specific needs reflected by the constraint index as the priority object in the operation process, and when the constraint index is different, the priority object is also different.

Specifically, when the robot obtains the pose index, it indicates that the robot gives priority to the pose of the manipulator during this operation, that is, in the process of subsequent execution of the work passing through the singular point, the position and attitude of the trajectory of the end of the manipulator are given priority Accuracy; when the robot obtains the speed index, it indicates that the robot gives priority to the speed of the manipulator during this operation, that is, in the process of subsequent execution of the operation passing through the singular point, the problem of sudden change and overrun of the robot joint speed is given priority; when the robot When the trajectory deviation index is obtained, it indicates that the robot gives priority to the allowable deviation range of the trajectory of the manipulator during this operation, that is, the safety and continuity of the robot's working process are given priority.

S120. Determine at least one traffic strategy and traffic loss value corresponding to each singular region according to at least one constraint index.

In this embodiment, after obtaining at least one constraint index, the six-axis robot can determine the corresponding passage strategy based on the constraint index, wherein the passage strategy can be to make the robot arm pass through the corresponding singular area smoothly in the subsequent operation process At the same time, the traffic loss value corresponding to the traffic strategy can also be determined based on the constraint index, where the traffic loss value can be the numerical change of a specific parameter, at least used to represent the difference between the robot and the original traffic strategy when choosing the traffic strategy. The difference in the passing strategy (pre-edited initial movement trajectory for the six-axis robot). The robot can obtain at least one constraint index. Therefore, when there are multiple constraint indexes, the determined traffic strategy and traffic loss value are also different with different constraint indexes.

The situation when the constraint indicators obtained by the robot are pose indicators, velocity indicators and trajectory deviation indicators are respectively described below.

(1) When the robot obtains the pose index, it can determine the joint space motion combined with the variable configuration scheme as the general strategy. Further, when the robot maintains the position and attitude accuracy of the end trajectory, it will inevitably slow down the manipulator. speed of movement. Therefore, based on the original programming trajectory and the traffic strategy corresponding to the pose index, the difference between the original passing time and the actual passing time of the robot in the singular area can be calculated, and the calculated difference can be used as The traffic loss value corresponding to the constraint condition of the indicator;

(2) When the robot obtains the speed index, it can determine the speed-down plan as the passing strategy. Further, when the robot prioritizes the sudden change and overrun of the robot joint speed, it will inevitably sacrifice the robot's motion speed and motion time. . Therefore, based on the original programming trajectory and the traffic strategy corresponding to the speed index, the increased movement time of the robot during the operation can be calculated, and the calculated movement time can be used as the traffic loss value corresponding to the constraint condition of the speed index;

(3) When the robot obtains the trajectory deviation index, it can determine the scheme based on the Bezier curve smooth passage as the general strategy. Further, when the robot gives priority to the allowable deviation range of the trajectory of the manipulator, it may appear in the user-given When the Bezier curve planned within the allowable deviation of the trajectory cannot avoid the singular point, at this time, it can be determined that the combined deceleration scheme or expanding the trajectory deviation is an alternative scheme, and at the same time, the traffic loss value of the alternative scheme can be determined .

S130. Determine a target traffic strategy based on the traffic loss values corresponding to each traffic strategy, so as to pass through the corresponding singular region based on the target traffic strategy.

In this embodiment, when a set of corresponding traffic strategies and traffic loss values are determined based on a constraint condition, the strategy can be directly used as the target traffic strategy; when multiple sets of corresponding traffic strategies and traffic loss values are determined based on a constraint condition loss value, or, when multiple sets of corresponding traffic strategies and traffic loss values are determined based on multiple constraints, it is also necessary to select a specific A group of is used as the target traffic policy. It can be understood that for the singular area in the pre-planned path, the target passing strategy is the optimal solution for the six-axis robot to pass through the singular area smoothly.

Furthermore, after determining the target traffic strategy, when the six-axis robot passes through the singular area in the subsequent operation process, it can avoid the singular points in the area according to the target traffic strategy, so that the robot can complete the task under the premise of satisfying the constraints. task for this job.

In the technical solution of this embodiment, if it is determined that the pre-planned path includes at least one singular area, at least one pre-configured constraint index is obtained. It can be understood that based on the constraint index, the subsequent processing process can be more in line with actual needs; according to at least one Constraint indicators, determine at least one traffic strategy and traffic loss value corresponding to each singular area, and further, determine the target traffic strategy based on the traffic loss value corresponding to each traffic strategy, so as to pass through the corresponding singular area based on the target traffic strategy, not only It can ensure that the robot passes through the singularity smoothly without adding special tooling to the robot, taking into account the scope of application and versatility of the robot. At the same time, the traffic strategy determined based on the constraint index meets the requirements of the user's original programming trajectory and avoids Situations occur in which trajectories are replanned in the course of work leading to unexpected results.

Embodiment two

Fig. 2 is a schematic flowchart of a singularity avoidance method provided by Embodiment 2 of the present invention. On the basis of the foregoing embodiments, according to the user's programmed trajectory, the singularity check of the robot's motion path is performed in advance and a prompt is given. It enables users to actively adjust the current route plan, which improves the flexibility of the plan; determines the corresponding singularity range threshold based on the constraint index, and obtains the quantified traffic loss value as the singularity evaluation, which solves the problem of highly algorithmic and abstract singularity evaluation The problem of the method reduces the requirements for the professionalism of the user. Among them, when the Cartesian control is used to convert to the joint space for re-planning, the trajectory accuracy of the robot end when it passes through the singular area is guaranteed by combining with the variable configuration method; Display multiple sets of traffic strategies and traffic loss values for users, so that users can flexibly choose the ideal processing strategy according to actual needs. For its specific implementation, refer to the technical solution of this embodiment. Wherein, technical terms that are the same as or corresponding to those in the foregoing embodiments will not be repeated here.

As shown in Figure 2, the method specifically includes the following steps:

S210. Determine the Jacobian matrix corresponding to each sampling point, and determine at least one singular value corresponding to each sampling point according to the Jacobian matrix; determine according to at least one singular value of each sampling point and a preset singularity threshold The singular point, and the region to which the singular point belongs is the singular region.

In this embodiment, in order to determine whether there are singular points and regions in the motion trajectory written by the user based on the programming language for the six-axis robot, the user's programming instructions can be pre-planned and interpolated by offline verification. Compensation is to calculate the joint angles of each joint of the robot at each working moment before the robot performs the movement. In the actual application process, the Jacobian matrix corresponding to each sampling point can be determined first. It can be understood that the sampling point is each joint of the robot. According to the schematic diagram of the six-axis robot in Figure 3, the sampling point can be There are 6 (ie, joints 1 to 6), and this process will be described in detail below.

Firstly, the forward and inverse kinematics model of the robot is established according to the configuration DH parameters of the robot. Those skilled in the art should understand that the DH model is widely used in the field of robot control as a standard method for expressing robots and modeling robots. Let me repeat. The forward and inverse kinematics model is to describe the joint angle q_i (q=1, 2, 3, 4, 5, 6) of the robot’s six joints and the robot’s end pose (P _x , P _x , P _x , α, β, γ) transformation matrix, using this transformation matrix, the position information and attitude information of the robot can be decoupled. The relative joint angles of the position coordinates P _x , P _x , P _x of the end and the pose coordinates α, β, γ (three components in the form of Euler angles) of the robot actuator end are separated.

Further, pre-planning interpolation is performed on the user's programming instructions. In the actual application process, if planning is carried out in Cartesian space, it can be transformed into joint space through inverse kinematics after planning; if planning is carried out in joint space, then Imputation can be done directly. At the same time, it should be noted that since the motion controllers of the six-axis robot are all discrete digital systems, the process of the robot from the initial position to the target position is not completed in one step, but will go through many intermediate moments and intermediate positions. The interval between two intermediate moments is a motion cycle. Through the process of pre-planning interpolation, the variables of angle q_i, velocity dq_i and acceleration ddq_i of each joint of the robot in each motion cycle can be obtained.

Finally, the current Jacobian matrix of the robot can be calculated based on the joint angle q_i of each interpolation cycle. Among them, the interpolation cycle is the time interval between sending motion commands to the servo drive of the robot joint motor twice, and the Jacobian matrix is to use the 6 components of the robot’s end pose to obtain partial derivatives for the 6 joint angles, and The obtained partial derivatives form a 6*6 matrix. It can be understood that the Jacobian matrix corresponds to the current joint angle of the robot.

In this embodiment, after the Jacobian matrix is determined, at least one singular value corresponding to each sampling point can be obtained by performing singular value (svd) decomposition on the Jacobian matrix. For a six-axis robot, there are six singular values respectively. One, that is, sigma1 ~ sigma6. Further, the condition number cond_num=sigma1/sigma6 of the Jacobian matrix can be obtained by dividing the maximum and minimum singular values. After comparing the condition number cond_num with the preset threshold cond_limit, if cond_num>cond_limit holds true, then the decision The robotic arm will enter the singular area under the above angles, otherwise, it is determined that the robotic arm is in the normal area and no special treatment is required.

Furthermore, based on the user's programmed trajectory, after using the above method to judge the joint variables of the entire trajectory multiple times, it can be determined whether there is a singular area in the entire trajectory of the six-axis robot manipulator, and at the same time, it can be obtained. corresponding judgment results. It should be noted that the above-mentioned process of determining whether there is a singular region in the user-programmed trajectory can be completed in an off-line verification manner.

In this embodiment, before the robot is put into use, after judging the singular point and the singular area in the program segment in advance and obtaining the judgment result, if the result shows that the manipulator will not enter the singular state in the entire motion trajectory, Then directly send all the joint variables to the joint driver in order to make the robot move; if the judgment result shows that the robot will enter a singular state in the entire trajectory, the user will be notified of the specific position of the singular point, and the user can choose whether to take the initiative Adjusting the current path plan of the robot, that is, providing a channel for the user to adjust the trajectory of the robot, so as to avoid the singularity point in the path of the robot in advance, and improve the flexibility of the plan.

S220. If it is determined that the pre-planned path includes at least one singular region, acquire at least one pre-configured constraint index.

In this embodiment, if the result of the determination indicates that the robotic arm will enter a singular state during the entire trajectory, and the user has not made any adjustments to the current path of the robot due to the constraints of the actual environment, at least one pre-configured constraint index is obtained, The singularity problem in this job task is handled by online processing.

S230. Determine at least one traffic strategy and traffic loss value corresponding to each singular region according to at least one constraint index.

In a practical application process, the constraint index may be at least one of a pose index, a velocity index, and a trajectory deviation index. The above constraint indexes and their corresponding traffic strategies and traffic loss values are described below.

Optionally, if the constraint index includes the pose index, determine the traffic strategy corresponding to each singular region as planning for each joint control, obtain the joint angle value corresponding to each joint, and use the first joint and the last Under the condition that the angle value of one joint remains unchanged, the joint poses of other joints are adjusted based on the preset pose determination function.

Specifically, according to the derivation of the Jacobian matrix, it can be determined that when the joint angle of joint 5 is 0° or 180°, the determinant of the Jacobian matrix is equal to 0, and the robot will be in a singular state of the wrist. Therefore, in the pose index The singular constraint index threshold limit5 of the joint 5 is included, and at the same time, the joint angle theta5 of the joint 5 is used as the singularity index. When the absolute value of the angle of joint 5 is less than the preset threshold limit5 (ie -limit5<theta5<limit5), it is determined that the manipulator has entered the singular region. At this time, the joint space corresponding to the pose index can be combined with the variable configuration The adoption scheme, the scheme will be described in detail below in conjunction with accompanying drawing 3.

Referring to the structure of the robot arm in Figure 3, it can be seen that when the joint 5 is located in the singular area, the 4th axis and the 6th axis are parallel to each other, and because the 2nd axis, 3rd axis, and 4th axis are themselves parallel to each other, therefore, the 2nd axis, 3rd axis, and 4th axis parallel to the 6 axes. At this time, the joint space planning is carried out in the singular area, and multiple sets of joint angle values q ₁ to q 6 of the robot joint 1 to joint ₆ are obtained, and then the final planning value of the Cartesian control before q ₁ enters the singular area remains unchanged, In this way, the influence of the change of _q1 on the trajectory of the robot end is eliminated. At the same time, because q ₅ always changes around 0 degrees, the 2-axis, 3-axis, 4-axis and 6-axis can be used as a parallel four-axis manipulator. Further, using the inverse kinematics properties of the parallel four-axis manipulator, in Passing through the 5-axis singular range while the end pose remains unchanged, this process can be understood as using the 2-axis, 3-axis, and 4-axis to adjust the position of the robot end, and using the 6-axis to adjust the attitude of the robot end. Specifically, the calculation formula for adjusting the end pose of the robot based on the above four axes (that is, the preset pose determination function) includes:

When the robot joint pose includes joint position coordinates, according to the initial angles of the 2-axis, 3-axis, and 4-axis, based on the forward kinematics formula, the pose of the robot’s end joint 6 can be determined as:

P _x ＝L ₁ cosq ₂ +L ₂ cos(q ₂ +q ₃ )+L ₃ cos(q ₂ +q ₃ +q ₄ )

P _y ＝L ₁ sinq ₂ +L ₂ sin(q ₂ +q ₃ )+L ₃ sin(q ₂ +q ₃ +q ₄ )

P _hi =q ₂ +q ₃ +q ₄

Among them, P _x and P _y are the position coordinates of the end of the robot, q ₁ ~ q ₄ respectively refer to the angle values of the four joints of the robot, P _hi refers to the attitude angle of the end of the robot, L ₁ , L ₂ , and L ₃ are the joints The distance between 2 and joint 3, joint 3 and joint 4, joint 4 and joint 6. When the angle of the 2-axis changes, the position coordinates of the 3-axis can be determined as:

P _3x ＝ L ₁ cos q′ ₁

P _3y = L ₁ sin q′ ₁

Based on this, the position coordinates of the end joint 6 of the robot relative to the 3-axis are:

P _63x =P _x -P _3x

P _63y =P _y -P _3y

Through the above calculation process, the singularity problem can be transformed into the inverse solution problem of a planar 2R manipulator from 3 to 6 axes (that is, a manipulator with two parallel rotating joints on the plane), and its inverse solution calculation and analysis . There are two groups of feasible solutions in the calculation results of the inverse solution, as shown in 3′ and 3″ in Fig. 4, when selecting the optimal solution, you can choose the group with the same configuration as the initial intersection, and use 6 The axis compensates the change of the terminal attitude angle, so that the 6-axis rotates by the same angle in the opposite direction of the change of the terminal attitude angle, thus ensuring that the position and attitude of the end of the robot arm pass through the singular point. When it is determined that the 5-axis passes through the singularity After the limit (that is, when theta5<-limit5 or theta5>limit5), switch the working state of the robot to the normal motion state, and continue to execute the task according to the original programmed trajectory.

Further, according to the original passage time and the actual passage time corresponding to the singular area, the passage loss value corresponding to the passage strategy can be determined. That is to say, in the case of maintaining the accuracy of the trajectory of the robot's end, the movement speed of the robot will be reduced. By calculating the difference between the original time origin_time and the actual time real_time of the robot in the singular area, the passing time of the pose index can be obtained. The traffic loss value corresponding to the strategy.

In this embodiment, when Cartesian controls are used to convert to joint space for replanning, the trajectory accuracy of the end of the robot when it passes through the singular region is guaranteed by combining with the variable configuration method.

Optionally, if the constraint index is a velocity index, the traffic strategy corresponding to each singular region is to determine the actual joint velocity of each joint, and determine the theoretical joint velocity of each joint according to each actual joint velocity, so as to pass through Singular area.

In this embodiment, when the robot uses the joint deceleration ratio in the speed index as the singularity index, it can adopt the solution of passing through at a reduced speed. Specifically, the process of determining the theoretical joint speed of each joint according to each actual joint speed includes: when it is detected that there is a target actual joint speed whose actual joint speed is greater than the preset joint speed threshold, then according to the difference between the actual joint speed of each target and the preset The speed threshold of the joint speed determines the speed drop ratio corresponding to the actual joint speed of each target; the maximum speed drop ratio is used as a reference to adjust the actual joint speed of each joint to obtain the theoretical joint speed of each joint. Wherein, the deceleration ratio ratio_i refers to the ratio of the joint speed dq_i calculated by inverse kinematics exceeding the allowable joint speed vmax_i, that is, ratio_i=(dq_i-vmax_i)/dq_i*100%.

Exemplarily, when the calculated speed of one of the joints 1 to 6 exceeds the allowed speed of the joint, the actual speed is set as the allowed speed of the joint, that is, vreal_i=vmax_i, and the reduction ratio ratio_i is calculated based on this. If there are more than two joints overspeeding, the joint with the largest deceleration ratio will be used as the benchmark, and the actual speeds of the other five joints will decrease in the same proportion, that is, vreal_i=dq_i*(1-ratio_i), so as to ensure that the speed of each joint is moderately maintained at within the speed adjustment range set by the user. When the calculation speed of all joints returns to the normal range (ie when dq_i ≤ vmax_i), switch the working state of the robot to the normal motion state, and continue to execute the task according to the original programmed trajectory.

Further, according to the theoretical joint speed, actual joint speed, actual passing time and theoretical passing time corresponding to each singular region, the passage loss value corresponding to each singular region is determined. That is to say, adopting the way of slowing down the movement speed of the robot also increases the overall running time of the machine. Therefore, the increased running time can be used as the passing loss value.

Optionally, if the constraint index is a trajectory deviation index, the traffic strategy corresponding to each singular region is to determine the original trajectory corresponding to the singular region, and process each original trajectory according to the preset displacement deviation to obtain at least one Bezier curve corresponding to the singular area, so as to pass through the corresponding singular area according to each Bezier curve.

In this embodiment, if the constraint condition is the trajectory deviation index, then the condition number cond_num of the Jacobian matrix is used as the singularity index, and when the condition number of the Jacobian matrix reaches the threshold (i.e. when cond_num>cond_limit), use Bessel A scheme for the smooth passage of the Curve. Specifically, with the allowable deviation cart_err_limit set by the user as the constraint, a new Bezier smooth trajectory is planned for the robot, and the robot moves according to this new trajectory. At the same time, the movement time of this trajectory remains the same as the original trajectory, that is, at any time during the movement of the robot along this trajectory, the pose deviation from the original trajectory will not exceed the allowable deviation of the trajectory set by the user, that is, cart_err≤ cart_err_limit. Among them, the pose deviation cart_err is obtained by taking the square sum of the position deviation and the attitude deviation and then taking the square root.

Further, it is determined whether at least one Bezier curve corresponding to each singular region can pass through the singular region, and whether it can pass through is used as a passing loss value. That is to say, when adopting the traffic strategy corresponding to the constraints of the trajectory deviation index, it may appear that the Bezier curve planned within the allowable deviation of the trajectory given by the user cannot avoid the singularity point. At this time, it is necessary to Combine the deceleration scheme or the scheme of enlarging the trajectory deviation as an alternative scheme, and determine the traffic loss value corresponding to the alternative scheme.

S240. Use the traffic strategy corresponding to the minimum traffic loss value as the target traffic strategy, and pass through the corresponding singular region based on the target traffic strategy.

In this embodiment, when multiple sets of traffic strategies and traffic loss values are determined based on one or more constraint conditions, the target traffic strategy can be obtained by using the minimum traffic loss value as a filter condition, that is, the robot will perform tasks in the subsequent During the task, a set of traffic strategies with the smallest pose or velocity deviation from the original programmed trajectory is used as the target traffic strategy. After the target traffic strategy is determined, the mechanical arm of the six-axis robot can execute the task according to the target traffic strategy, so as to pass the singular points in each singular area smoothly.

It should be noted that if at least one constraint index includes one, when the traffic strategy corresponding to the constraint index cannot pass through each singular area, the target display area displayed with the traffic strategy and traffic loss value corresponding to the other constraint index , for the user to select.

It can be understood that when the constraint strategy corresponding to the constraint index cannot meet the work requirements, other traffic strategies and traffic loss values can also be displayed to the user, and the user can intuitively understand through the specific quantitative cost index corresponding to each traffic strategy The cost of each traffic strategy, that is, to clarify the impact of each traffic strategy on the original programming trajectory, so that users can flexibly choose the ideal processing strategy according to actual needs.

In the technical solution of this embodiment, according to the user's programmed trajectory, the singularity check of the robot's motion path is performed in advance and a prompt is given, so that the user can actively adjust the current path solution, which improves the flexibility of the solution; The singularity range threshold, and the quantified traffic loss value is used as the singularity evaluation, which solves the problem of highly algorithmic and abstract method of singularity evaluation, and reduces the requirements for user professionalism. Among them, the Cartesian control is used to convert to the joint space When re-planning, combined with the variable configuration method, the trajectory accuracy when the robot end passes through the singular area is guaranteed; multiple sets of traffic strategies and traffic loss values are displayed for the user, so that the user can flexibly choose the ideal processing strategy according to actual needs .

Embodiment Three

As an optional embodiment of the foregoing embodiment, FIG. 5 is a flow chart of a singularity avoidance method provided in Embodiment 3 of the present invention. In order to clearly introduce the technical solution of this embodiment, the application scenario can be introduced as an example where a six-axis robot processes singular points in the workspace. In scenarios where singularities in the trajectory are handled.

See Figure 5. In order for the six-axis robot to perform tasks, the staff first need to write a program segment reflecting a specific motion trajectory based on the programming language. After the robot detects the program, it can pre-check the user's programming instructions through offline verification. Planning interpolation, that is, to check in advance whether there are singular points in the program segment in an offline manner. If it is determined that the robot does not have a singular state in the entire trajectory based on the programming instructions, all joint variables are directly sent to the joint driver in sequence to make the robotic arm perform the task. Entering into a singular state, that is, when there is a singular area in the motion trajectory, the user can adjust the robot's motion trajectory in advance by modifying the programmed program segment.

Continuing to refer to FIG. 5 , when the actual working environment restricts the user to modify the trajectory of the robot, it is necessary to perform online processing for the singular points in the singular region. The specific online processing method includes three stages. In the first stage, the constraint index set by the user is converted into the corresponding singularity index. The constraint index includes the priority of the task (position priority or speed priority) and the allowable deviation of the trajectory. Range, when converted to the underlying mathematical evaluation index, the pose index corresponds to the joint angle theta5 of joint 5, the speed index corresponds to the joint deceleration ratio ratio_i (i=1,2,3,4,5,6), and the trajectory The allowable deviation range corresponds to the condition number cond_num of the Jacobian matrix. In the second stage, according to the converted underlying mathematical evaluation index, the corresponding traffic strategy can be adopted to meet the job requirements. Among them, when the constraint index is a pose index, the scheme of joint space motion combined with variable configuration can be adopted. In this way, the position and attitude accuracy of the trajectory of the end effector of the manipulator can be guaranteed when the robot passes through the singular point; the constraint index is When the speed index is used, the scheme of slowing down can be used to solve the problem of joint speed mutation and overrun when passing the singularity within the speed adjustment range set by the user; when the constraint index is the allowable deviation range of the trajectory, Besser can be used The Err curve smooth pass scheme, this method is used to deal with the singular point as a non-critical working point, the robot can continue to work around the singular point within the range of the trajectory deviation value set by the user, ensuring the safety and continuity of the robot's work . In the third stage, specific quantitative cost indicators can be given in the form of passing loss values for each of the above-mentioned processing schemes, which are used to evaluate the impact of the current processing scheme on the motion trajectory reflected by the original program.

Continuing to refer to Figure 5, when multiple traffic strategies are determined, these schemes and their cost indicators (traffic loss value) can also be displayed on a specific page, so that users can evaluate whether each scheme is feasible and choose the optimal one. The scheme is used as the target traffic strategy. After the target traffic strategy is determined, the robot can execute the task according to the determined traffic strategy, so that the manipulator can pass the singular point in the singular area smoothly. If the user evaluates that these solutions are not feasible, you need to Rewrite the corresponding program for the trajectory of the robot, and perform the above steps again to obtain the target traffic strategy.

The beneficial effects of the above-mentioned technical solution are: not only can ensure that the robot passes through the singularity smoothly, but also does not need to add special tooling to the robot, taking into account the scope of application and versatility of the robot, and at the same time, the traffic strategy determined based on the constraint index satisfies the needs of users. The requirement of the original programmed trajectory avoids unexpected results caused by the robot re-planning the trajectory during the working process.

Embodiment Four

Fig. 6 is a structural block diagram of a singularity avoidance device provided in Embodiment 4 of the present invention, which can execute the singularity avoidance method provided in any embodiment of the present invention, and has corresponding functional modules and beneficial effects for executing the method. As shown in FIG. 6 , the device is applied to a six-axis robot, and specifically includes: a constraint index acquisition module 310 , a passage strategy determination module 320 , and a target passage strategy determination module 330 .

A constraint index acquisition module 310, configured to acquire at least one preconfigured constraint index if it is determined that the pre-planned path includes at least one singular region; wherein, the constraint index includes a pose index, a speed index, and a trajectory deviation index at least one.

The traffic strategy determination module 320 is configured to determine at least one traffic strategy and traffic loss value corresponding to each singular region according to the at least one constraint index.

The target traffic strategy determining module 330 is configured to determine a target traffic strategy based on the traffic loss value corresponding to each traffic strategy, so as to pass through the corresponding singular area based on the target traffic strategy.

On the basis of the above technical solutions, the device for avoiding the singularity further includes a singularity determination module.

A singular point determination module, configured to determine the Jacobian matrix corresponding to each sampling point, and determine at least one singular value corresponding to each sampling point according to the Jacobian matrix; according to at least one singular value of each sampling point and a predetermined Set a singularity threshold, determine a singularity point, and use the region to which the singularity point belongs as the singularity region.

On the basis of the above technical solutions, the traffic strategy determination module 320 includes a traffic strategy determination unit based on a pose index, a traffic strategy determination unit based on a speed index, and a traffic strategy determination unit based on a trajectory deviation index.

The traffic strategy determination unit based on the pose index is used to determine the traffic strategy corresponding to each singular area if the constraint index includes a pose index, and plan each joint control to obtain a joint angle value corresponding to each joint. , and under the condition that the angle values of the first joint and the last joint remain unchanged, the joint poses of other joints are adjusted based on the preset pose determination function; wherein, the joint poses include joint position coordinates; according to the According to the original passing time and actual passing time corresponding to the singular region, the passage loss value corresponding to the passing strategy is determined.

The traffic strategy determination unit based on the speed index is used to determine the actual joint speed of each joint as the traffic strategy corresponding to each singular area if the constraint index is a speed index, and determine the theory of each joint according to each actual joint speed Joint speed, to pass through the singular area based on the theoretical joint speed; determine the traffic loss value corresponding to each singular area according to the theoretical joint speed, actual joint speed, actual passing time and theoretical passing time corresponding to each singular area .

Optionally, the traffic strategy determination unit based on the speed index is further configured to: when detecting that there is a target actual joint speed whose actual joint speed is greater than the preset joint speed threshold, according to the difference between each target actual joint speed and the preset joint speed The speed threshold is used to determine the speed drop ratio corresponding to the actual joint speed of each target; the maximum speed drop ratio is used as a reference to adjust the actual joint speed of each joint to obtain the theoretical joint speed of each joint.

The traffic strategy determination unit based on the trajectory deviation index is used to determine the original trajectory corresponding to the singular area according to the preset trajectory if the constraint index is the trajectory deviation index. The displacement deviation processes each original trajectory to obtain at least one Bezier curve corresponding to each singular region, so as to pass through the corresponding singular region according to each Bezier curve; determine at least one Bezier curve corresponding to each singular region Whether the curve can pass through the singular region is used as the passage loss value.

On the basis of the above technical solutions, the singularity avoiding device further includes a traffic strategy display module.

A traffic strategy display module, configured to display the traffic strategy and traffic loss corresponding to other constraint indexes when the traffic strategy corresponding to the constraint index cannot pass through each singular area The target display area where the value is displayed for the user to select.

Optionally, the target traffic strategy determination module 330 is further configured to use the traffic strategy corresponding to the minimum traffic loss value as the target traffic strategy, and pass through the corresponding singular area based on the target traffic strategy.

In the technical solution provided by this embodiment, if it is determined that the pre-planned path includes at least one singular area, at least one pre-configured constraint index is obtained. It can be understood that the subsequent processing process can be more in line with actual needs based on the constraint index; At least one constraint index, determine at least one traffic strategy and traffic loss value corresponding to each singular area, and further, determine a target traffic strategy based on the traffic loss value corresponding to each traffic strategy, so as to pass through the corresponding singular area based on the target traffic strategy , not only can ensure that the robot passes through the singularity smoothly, but also does not need to add special tooling to the robot, taking into account the scope of application and versatility of the robot. It prevents the robot from re-planning the trajectory during the work process and causing unexpected results.

The singularity avoiding device provided in the embodiments of the present invention can execute the singularity avoiding method provided in any embodiment of the present invention, and has corresponding functional modules and beneficial effects for executing the method.

It is worth noting that the units and modules included in the above-mentioned device are only divided according to functional logic, but are not limited to the above-mentioned division, as long as the corresponding functions can be realized; in addition, the specific names of each functional unit are only In order to facilitate mutual distinction, it is not used to limit the protection scope of the embodiments of the present invention.

Embodiment five

FIG. 7 is a schematic structural diagram of an electronic device provided by Embodiment 5 of the present invention. FIG. 7 shows a block diagram of an exemplary electronic device 40 suitable for implementing an example implementation of the present invention. The electronic device 40 shown in FIG. 7 is only an example, and should not limit the functions and scope of use of the embodiments of the present invention.

As shown in FIG. 7, electronic device 40 takes the form of a general-purpose computing device. Components of the electronic device 40 may include, but are not limited to: one or more processors or processing units 401 , a system memory 402 , and a bus 403 connecting different system components (including the system memory 402 and the processing unit 401 ).

Bus 403 represents one or more of several types of bus structures, including a memory bus or memory controller, a peripheral bus, an accelerated graphics port, a processor, or a local bus using any of a variety of bus structures. These architectures include, by way of example, but are not limited to Industry Standard Architecture (ISA) bus, Micro Channel Architecture (MAC) bus, Enhanced ISA bus, Video Electronics Standards Association (VESA) local bus, and Peripheral Component Interconnect ( PCI) bus.

Electronic device 40 typically includes a variety of computer system readable media. These media can be any available media that can be accessed by electronic device 40 and include both volatile and nonvolatile media, removable and non-removable media.

System memory 402 may include computer system readable media in the form of volatile memory, such as random access memory (RAM) 404 and/or cache memory 405 . The electronic device 40 may further include other removable/non-removable, volatile/nonvolatile computer system storage media. By way of example only, storage system 406 may be used to read and write to non-removable, non-volatile magnetic media (not shown in FIG. 7, commonly referred to as a "hard drive"). Although not shown in FIG. 7, a disk drive for reading and writing to removable nonvolatile disks (e.g., "floppy disks") may be provided, as well as for removable nonvolatile optical disks (e.g., CD-ROM, DVD-ROM or other optical media) CD-ROM drive. In these cases, each drive may be connected to bus 403 via one or more data media interfaces. Memory 402 may include at least one program product having a set (eg, at least one) of program modules configured to perform the functions of various embodiments of the present invention.

A program/utility 408 having a set (at least one) of program modules 407 may be stored, for example, in memory 402, such program modules 407 including but not limited to an operating system, one or more application programs, other program modules, and program data , each or some combination of these examples may include implementations of network environments. The program module 407 generally executes the functions and/or methods of the described embodiments of the present invention.

The electronic device 40 may also communicate with one or more external devices 409 (such as a keyboard, pointing device, display 410, etc.), communicate with one or more devices that enable a user to interact with the electronic device 40, and/or communicate with Any device (eg, network card, modem, etc.) that enables the electronic device 40 to communicate with one or more other computing devices. Such communication may occur through input/output (I/O) interface 411 . Moreover, the electronic device 40 can also communicate with one or more networks (such as a local area network (LAN), a wide area network (WAN) and/or a public network such as the Internet) through the network adapter 412 . As shown, network adapter 412 communicates with other modules of electronic device 40 via bus 403 . It should be appreciated that although not shown in FIG. 7, other hardware and/or software modules may be used in conjunction with electronic device 40, including but not limited to: microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, tape Drives and data backup storage systems, etc.

The processing unit 401 executes various functional applications and data processing by running the programs stored in the system memory 402 , for example, implementing the method for avoiding the singularity provided by the embodiments of the present invention.

Embodiment six

Embodiment 6 of the present invention also provides a storage medium containing computer-executable instructions, and the computer-executable instructions are used to implement a singularity avoidance method when executed by a computer processor.

The method includes:

If it is determined that at least one singular region is included in the pre-planned path, at least one pre-configured constraint index is obtained; wherein the constraint index includes at least one of a pose index, a speed index, and a trajectory deviation index;

Determine at least one traffic strategy and traffic loss value corresponding to each singular area according to the at least one constraint index;

Based on the traffic loss value corresponding to each traffic strategy, a target traffic strategy is determined, so as to pass through the corresponding singular area based on the target traffic strategy.

The computer storage medium in the embodiments of the present invention may use any combination of one or more computer-readable media. The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples (non-exhaustive list) of computer readable storage media include: electrical connections with one or more leads, portable computer disks, hard disks, random access memory (RAM), read only memory (ROM), Erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination of the above. In this document, a computer-readable storage medium may be any tangible medium that contains or stores a program that can be used by or in conjunction with an instruction execution system, apparatus, or device.

A computer readable signal medium may include a data signal carrying computer readable item code in baseband or as part of a carrier wave. Such propagated data signals may take many forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination of the foregoing. A computer-readable signal medium may also be any computer-readable medium other than a computer-readable storage medium, which can send, propagate, or transmit a program for use by or in conjunction with an instruction execution system, apparatus, or device. .

Item code embodied on a computer readable medium may be transmitted by any suitable medium, including - but not limited to wireless, wireline, optical fiber cable, RF, etc., or any suitable combination of the foregoing.

Computer program code for carrying out operations of embodiments of the present invention may be written in one or more programming languages, or combinations thereof, including object-oriented programming languages—such as Java, Smalltalk, C++, including A conventional procedural programming language - such as "C" or a similar programming language. The Project Code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer, or entirely on a remote computer or server. In cases involving a remote computer, the remote computer may be connected to the user computer through any kind of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (such as through an Internet Service Provider). Internet connection).

Note that the above are only preferred embodiments of the present invention and applied technical principles. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the protection scope of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and can also include more other equivalent embodiments without departing from the concept of the present invention, and the present invention The scope is determined by the scope of the appended claims.

Claims (11)

1. A singularity avoidance method is applied to a six-axis robot and comprises the following steps:

if the fact that the pre-planned path comprises at least one singular area is determined, at least one pre-configured constraint index is obtained; wherein the constraint index comprises at least one of a pose index, a speed index and a trajectory deviation index;

determining at least one traffic strategy and traffic loss value corresponding to each singular area according to the at least one constraint index;

and determining a target traffic strategy based on the traffic loss values corresponding to the traffic strategies so as to pass through the corresponding singular areas based on the target traffic strategy.

2. The method of claim 1, further comprising:

determining a Jacobian matrix corresponding to each sampling point, and determining at least one singular value corresponding to each sampling point according to the Jacobian matrix;

determining a singular point according to at least one singular value of each sampling point and a preset singular threshold, and taking a region to which the singular point belongs as the singular region.

3. The method of claim 1, wherein determining at least one traffic strategy and traffic loss value corresponding to each singular zone based on the at least one constraint index comprises:

if the constraint indexes comprise pose indexes, determining the pass strategy corresponding to each singular area as planning each joint control to obtain a joint angle value corresponding to each joint, and adjusting the joint poses of other joints based on a preset pose determination function under the condition that the first joint and the last joint angle value are unchanged; wherein the joint positions comprise joint position coordinates;

and determining a traffic loss value corresponding to the passing strategy according to the original passing time and the actual passing time corresponding to the singular area.

4. The method of claim 1, wherein determining at least one traffic policy and traffic loss value corresponding to each singular zone based on the at least one constraint indicator comprises:

if the constraint index is a speed index, determining the actual joint speed of each joint by the passing strategy corresponding to each singular area, and determining the theoretical joint speed of each joint according to each actual joint speed so as to pass through the singular area based on the theoretical joint speed;

and determining the traffic loss value corresponding to each singular area according to the theoretical joint speed, the actual traffic time and the theoretical traffic time corresponding to each singular area.

5. The method of claim 4, wherein determining a theoretical joint velocity for each joint from each actual joint velocity comprises:

when the target actual joint speed with the actual joint speed larger than the preset joint speed threshold value is detected, determining a speed reduction ratio corresponding to each target actual joint speed according to each target actual joint speed and the speed threshold value of the preset joint speed;

and taking the maximum speed reduction ratio as a reference, and adjusting the actual joint speed of each joint to obtain the theoretical joint speed of each joint.

6. The method of claim 1, wherein determining at least one traffic strategy and traffic loss value corresponding to each singular zone based on the at least one constraint index comprises:

if the constraint index is the track deviation index, determining an original track corresponding to each singular area by the passing strategy corresponding to each singular area, processing each original track according to preset displacement deviation to obtain at least one Bezier curve corresponding to each singular area, and passing through the corresponding singular area according to each Bezier curve;

determining whether at least one Bezier curve corresponding to each singular region can pass through the singular region and can pass through the singular region as the pass loss value.

7. The method of claim 1, further comprising:

and if the at least one constraint index comprises one constraint index, when the passing strategies corresponding to the constraint indexes cannot pass through each singular area, displaying the passing strategies corresponding to other constraint indexes and the passing loss value in a target display area for a user to select.

8. The method of claim 1, wherein determining a target traffic policy based on the traffic loss value corresponding to each traffic policy for passing through a corresponding singular zone based on the target traffic policy comprises:

and taking the traffic strategy corresponding to the minimum traffic loss value as a target traffic strategy, and passing through a corresponding singular area based on the target traffic strategy.

9. The singularity avoiding device is applied to a six-axis robot and comprises:

the constraint index acquisition module is used for acquiring at least one constraint index which is configured in advance if the fact that the path planned in advance comprises at least one singular area is determined; the constraint indexes comprise at least one of a pose index, a speed index and a track deviation index;

the traffic strategy determining module is used for determining at least one traffic strategy and traffic loss value corresponding to each singular area according to the at least one constraint index;

and the target traffic strategy determining module is used for determining a target traffic strategy based on the traffic loss value corresponding to each traffic strategy so as to pass through the corresponding singular area based on the target traffic strategy.

10. An electronic device, characterized in that the electronic device comprises:

one or more processors;

a storage device for storing one or more programs,

when executed by the one or more processors, cause the one or more processors to implement the singularity avoidance method of any of claims 1-8.

11. A storage medium containing computer-executable instructions for performing the method of avoiding a singularity according to any of claims 1-8 when executed by a computer processor.

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