CN106141472A - A kind of dual robot bilateral symmetry welding control method - Google Patents

Abstract

The invention discloses a kind of dual robot bilateral symmetry welding control method, this method uses the purpose of multi-robot Cooperation to be by bilateral symmetry weldering, only need to carry out dual robot cooperation, compared to the most universal monolateral welding manner of single robot, the design uses a controller to control, and Liang Tai robot is bilateral to be welded simultaneously, it is possible to effectively promote the deformation in welding efficiency, suppression welding process.

Description

Double-robot bilateral symmetric welding control method

Technical Field

The invention relates to the technical field of arc welding robots, in particular to a control method for bilateral symmetric welding of double robots.

Background

Arc welding is the most important material connection mode in the current mechanical manufacturing field. In the field of arc welding, welding of long welding seams (the length is more than or equal to 1m) and thin plate materials is the most difficult, because the welding of the long welding seams of the thin plates has more serious tool errors and thermal deformation caused by the length problem.

At present, for robot welding of thin plates and long welding seams, sectional welding, spot welding in advance or high-density clamp use are generally adopted to reduce welding deformation in the welding process of the thin plates and the long welding seams. The disadvantages of this welding method are: the sectional welding reduces the welding efficiency, and the use of the high-density clamp improves the tooling cost.

The invention provides a double-robot bilateral symmetric welding method, which adopts double robots to weld two sides of a thin plate and a long welding seam at the same time and can effectively inhibit welding deformation by utilizing the characteristic that the two sides of the welding seam are uniformly heated. The existing welding robots all mainly use a single robot system and lack the function of double-robot cooperation welding. The invention aims to solve the problem and provides a control method for bilateral symmetric welding of a double robot.

Disclosure of Invention

Aiming at the problem of welding the long welding seam thin plate, the invention provides a double-robot bilateral symmetric welding control method. The method adopts multi-robot cooperation to aim at bilateral symmetrical welding and needs to carry out double-robot cooperation control. Compared with the common multi-robot cooperation of the robots controlled by the multiple controllers, the robot control system has the advantages that one controller is used for controlling the two robots, communication among different controllers is avoided, and the precision of a data sending period is improved.

The technical scheme adopted by the invention is as follows: a double-robot bilateral symmetry welding control method comprises the following steps:

firstly, moving a main robot to a welding guide point;

moving the robot to a welding guide point;

thirdly, the main robot moves to the welding starting point;

fourthly, moving from the robot to the welding starting point;

the double robots enter a cooperation mode;

sixthly, the main robot moves to the welding tail end point and automatically calculates the welding tail end point of the slave robot;

seventhly, the double robots exit the cooperation mode;

moving the main robot to a welding exit point and moving the robot to the welding exit point.

Further, in the step, the master robot moves to the welding end point, the welding end point of the slave robot is automatically calculated, and the method for calculating the motion of the slave robot according to the motion of the master robot comprises the following steps:

the constraint relation of the double robots during bilateral symmetrical welding is recorded by q^l∈Rⁿ，q^f∈RⁿRespectively, a master robot joint angle, a slave robot joint angle, p (q)^l)∈R³，p(q^f)∈R³Respectively is the position vector of the central point of the tool hand of the main robot under the base coordinate system of the robot, r¹Representing a displacement vector from a master robot hand center point to a slave robot hand center point, a rotation matrixIs the posture representation of the robot tool hand under the robot base coordinate system,

$R_0^n=\[\begin{array}{ccc}n\left(q\right)& s\left(q\right)& a\left(q\right)\end{array}\]---\left(2\right)$

describing the pose of the robot tool hand by adopting a homogeneous transformation matrix, wherein the form of the homogeneous transformation matrix is as follows:

$H={\left[\begin{array}{cc}R& T\\ 0& 1\end{array}\right]}_{4\×4},H^{-1}={\left[\begin{array}{cc}{R}^T& -R^{T}T\\ 0& 1\end{array}\right]}_{4\×4}---\left(3\right)$

wherein R ∈ R^3×3Is a rotation matrix describing the pose of the robot tool hand, T ∈ R³The vector is used for describing the position of a tool hand of a robot, R and T need to designate a reference coordinate system before use, and a robot base coordinate system is generally selected as a tool hand position reference coordinate system; the desired motion trajectory of a robotic tool hand is typically represented by a time-varying homogeneous transformation matrix of the form:

$M\left(t\right)=\left[\begin{array}{cc}R\left(t\right)& T\left(t\right)\\ 0& 1\end{array}\right]---\left(4\right)$

homogeneous transformation matrix^mbP_m(t) the pose of the master robot tool hand under the master robot base coordinate system at time t,^sbP_s(t) the pose of the slave robot tool hand under the slave robot base coordinate system at the moment t; note the book^mbP_s(t) the pose of the slave robot tool hand in the master robot base coordinate system at the time t, then

^mbP_s(t)＝^mbH_sb·^sbP_s(t) (5)

Wherein^mbH_sbIs a homogeneous transformation matrix from a robot base coordinate system to a main robot base coordinate system;

note the bookFor the starting time of the two robots cooperating with the welding process, the pose of the master and slave robot tools at the time^mbp_m(t₀) And^sbp_s(t₀) (ii) a Note the book^mH_sIs t₀A homogeneous transformation matrix from the pose of the tool hand of the robot to the pose of the tool hand of the main robot at any time

^mbp_m(t₀)＝^mH_s·mbp_s(t₀) (6)

Substituting equation (5) into equation (6) at t ═ t₀Can be obtained

^mbp_m(t₀)＝^mH_s·^mbH_sb·^sbp_s(t₀) (7)

From equation (7), it can be found

^mH_s＝^mbp_m(t₀)·(^sbp_s(t₀))^-1·^sbH_mb(8)

Wherein^sbH_mbIs a matrix^mbH_sbThe inverse matrix of (a) represents a homogeneous transformation from the master robot base coordinate to the slave robot base coordinate system.

In the whole double-robot cooperation bilateral symmetrical welding process, the matrix^mH_sIs kept unchanged during the whole welding process, then

$\begin{array}{c}{p_{mb}}_m\left(t\right)={H_m}_s\·{p_{mb}}_s\left(t\right)\\ ={H_m}_s\·{H_{mb}}_{sb}\·{p_{sb}}_s\left(t\right)\\ ={p_{mb}}_m\left(t_0\right)\·{\left({p_{sb}}_s\right(t_0\left)\right)}^{-1}\·{H_{sb}}_{mb}\·{H_{mb}}_{sb}\·{p_{sb}}_s\left(t\right)\\ ={p_{mb}}_m\left(t_0\right)\·{\left({p_{sb}}_s\right(t_0\left)\right)}^{-1}\·{p_{sb}}_s\left(t\right)\end{array}---\left(9\right)$

From equation (9), it can be obtained

^sbp_s(，)＝^sbp_s(t₀)·(^mbp_m(t₀))^-1·^mbp_m(t) (10)

Equation (10) is the constraint relationship of the tool hand pose of the master-slave robot in the double-robot cooperation bilateral symmetric welding process. Also according to the motion track of the main robot (teaching track)^mbp_m(t) calculating a slave robot motion trajectory^sbp_s(t) ofThe theoretical foundation.

The invention has the beneficial effects that:

firstly, welding of bilateral welding seams is carried out simultaneously, so that the welding efficiency is improved, and the welding time is shortened;

the two sides of the double-side welding seam are symmetrically welded, and the two sides are uniformly heated, so that the welding thermal deformation of the welding seam is effectively inhibited;

and thirdly, the bilateral welding seam symmetric welding reduces the tool fixture and the implementation cost.

Drawings

Fig. 1 is a schematic system diagram of a double-robot bilateral symmetric welding control method provided by the invention. Optionally, one of the two robots is a master robot and the other is a slave robot. Without loss of generality, the left robot (1) can be selected as a main robot.

Detailed Description

The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. The described embodiments are only some embodiments of the invention, not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention provides a double-robot bilateral symmetric welding control method, which comprises the following steps:

firstly, a main robot moves to a welding guide point, and the welding guide point is taught to be automatically selected to be a proper position by an operator (referring to a selection principle during welding of a single robot);

moving the robot to a welding guide point, wherein the welding guide point is selected by a teaching operator (referring to a selection principle during welding of a single robot);

③ moving the main robot to the welding starting point, and recording the end pose of the main robot in the main robot base coordinate system as^mbp_m(t₀)；

④ move from robot to welding start point, when the end position of robot is recorded as^sbp_s(t₀)；

The double robots enter a cooperation mode;

sixthly, the main robot moves to the welding tail end point, the welding tail end point of the secondary robot is automatically calculated, and the bilateral symmetrical welding process of the double robots is started;

the core problem of the invention is how to automatically calculate the motion (pose) of the slave robot according to the motion (pose) of the master robot. The calculation is as follows:

the pose of the tail end of the main robot at the tail end point of welding is recorded in a base coordinate system of the main robot^mbp_m(t_f) The main robot is composed of^mbp_m(t₀) Move to^mbp_m(t_f) Corresponding to the welding process, the motion track of the main robot in the process is recorded as^mbp_m(t) is obtained according to equation (10)

^sbp_s(t)＝^sbp_s(t₀)·(^mbp_m(t₀))^-1·^mbp_m(t)

^sbp_s(t_f)＝^sbp_s(t₀)·(^mbp_m(t₀))^-1·^mbp_m(t_f)

Wherein,^sbp_s(t) is the automatically calculated slave robot motion trajectory,^sbp_s(t_f) Is an automatically calculated end point from the robot welding process.

Seventhly, the double robots quit the cooperative welding mode;

moving the main robot to a welding exit point and moving the robot to the welding exit point. The welding exit point is selected by an operator according to a selection principle of a single robot welding process.

Because the purpose of multi-robot cooperation is to carry out bilateral symmetric welding, the experiment only needs to carry out double-robot cooperation, and compared with the common double-robot cooperation of the robots controlled by two controllers, the double-robot cooperation control system has the advantages that one controller is used for controlling the two robots, communication among different controllers is avoided, and the precision of a data sending period is improved.

It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by a computer program and associated hardware, the computer program can be stored in a computer-readable storage medium, and the computer program can include the processes of the embodiments of the methods described above when the computer program is executed.

While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.

Claims (2)

1. A bilateral symmetric welding control method for a double robot is characterized by comprising the following steps:

firstly, moving a main robot to a welding guide point;

moving the robot to a welding guide point;

thirdly, the main robot moves to the welding starting point;

fourthly, moving from the robot to the welding starting point;

the double robots enter a cooperation mode;

sixthly, the main robot moves to the welding tail end point and automatically calculates the welding tail end point of the slave robot;

seventhly, the double robots exit the cooperation mode;

moving the main robot to a welding exit point and moving the robot to the welding exit point.

2. The dual-robot bilateral symmetry welding control method of claim 1, wherein the principle of calculating the motion of the slave robot according to the motion of the master robot in the steps of moving the master robot to the welding end point and automatically calculating the welding end point of the slave robot is as follows:

homogeneous transformation matrix^mbP_m(t) the pose of the master robot tool hand under the master robot base coordinate system at time t,^sbP_s(t) the pose of the slave robot tool hand under the slave robot base coordinate system at the moment t; note the book^mbP_s(t) is the pose of the slave robot tool hand under the master robot base coordinate system at the time t,^mbH_sbis a homogeneous transformation matrix from a robot base coordinate system to a main robot base coordinate system; note t₀Is the starting moment of the cooperative welding process, and the positions of the master robot hand and the slave robot hand are respectively^mbp_m(t₀) And^sbp_s(t₀) (ii) a Note the book^mH_sIs t₀A homogeneous transformation matrix from the pose of the tool hand of the robot to the pose of the tool hand of the main robot at any time

^sbp_s(t)＝^sbp_s(t₀)·(^mbp_m(t₀))^-1·^mbp_m(t) (1)

The formula (1) is the constraint relation of tool hand poses of the master-slave robot in the cooperative welding process of the double robots.