Multi-axis robot calibration method, system, electronic device and readable storage medium with ground track

Abstract

The present application relates to a calibration method, system, electronic device and readable storage medium for a multi-axis robot with a ground rail, the calibration method comprising the following steps: establishing a base coordinate system based on a robot base, and setting calibration points based on a world coordinate system; dividing the movement path of the robot base into several intervals; controlling the robot base to move from the starting point to the end point of each interval, and controlling the robot tool end to reset to the calibration point at the end point of the interval; obtaining the base movement information of the robot base from the starting point to the end point of the interval, and the corresponding reset stroke information of the robot tool end; calculating the direction vector corresponding to each interval based on reference information; determining the coordinate transformation relationship of each interval of the ground rail for the robot tool end in the base coordinate system based on the direction vector, interval position and interval length of each interval. The present application can control the movement error of the robot tool end within an allowable range when the robot causes slight deformation of the ground rail.

Description

Technical Field

[0001] The present application relates to the field of automation, and in particular to a calibration method, system, electronic device and readable storage medium for a multi-axis robot with a ground track. Background Art

[0002] With the improvement of automation in the manufacturing industry, robots have begun to be widely used in the production and manufacturing processes of various industries. Usually, the robot is fixed on a base and uses a joint arm to operate on the object to be measured. When the object to be measured is large (such as a train carriage or an airplane) or the workpiece to be grasped is far away from the installation body, it is necessary to expand the robot's operating radius. Usually, the solution of installing a ground rail (travel axis / seventh axis) on the robot can be adopted. The ground rail is connected to an encoder, and the ratio between the encoder increment and the sliding distance of the base is determined and can be obtained through calibration.

[0003] At present, the robot ground rail can be used directly for use scenarios with low precision requirements such as packaging, transportation, palletizing, and welding. For use scenarios such as high-precision processing, inspection, grasping, and installation, the accuracy loss is often required to be within ±0.5mm. However, since the ground rail may produce slight deformation during transportation and installation, or the ground is uneven, the actual working position of the robot tool end deviates from the theoretical position and does not meet the accuracy requirements. Summary of the invention

[0004] In order to control the movement error of the robot tool end within an allowable range when the robot causes slight deformation of the ground rail, the present application provides a calibration method, system, electronic device and readable storage medium for a multi-axis robot with a ground rail.

[0005] In the first aspect, the present application provides a calibration method for a multi-axis robot with a ground track, which adopts the following technical solution:

[0006] A calibration method for a multi-axis robot with a ground track comprises the following steps:

[0007] System building step: establishing a base coordinate system based on the robot base and setting calibration points based on the world coordinate system;

[0008] A zone division step, dividing the moving path of the robot base into several zones;

[0009] The operation step is to control the robot base to move from the starting point to the end point of each interval, and control the robot tool end to reset to the calibration point at the end point of the interval, wherein the robot tool end is located at the calibration point when the robot base is located at the starting point of the interval;

[0010] An information acquisition step, acquiring base movement information of the robot base from the starting point of the interval to the end point of the interval, and reset stroke information of the corresponding robot tool end; wherein the base coordinate system coordinate information and the reset stroke information are used as reference information and correspond to the interval;

[0011] A direction calculation step, calculating the direction vector corresponding to each interval based on the reference information;

[0012] The compensation calculation step determines the coordinate transformation relationship between the world coordinates of the robot tool end and the base coordinates of the robot working end for each section of the ground rail based on the direction vector, section position and section length of each section.

[0013] The ground rail is usually set on the ground, and the robot base slides on the ground rail. Therefore, the world coordinates are usually used to describe the position of the robot base, and the encoder value can also be used to describe the horizontal position of the robot base on the ground rail. Since the robot arm is set on the robot base, the base coordinate system is established based on the robot base, which can conveniently describe the spatial state of the robot tool end.

[0014] Since the robot may slightly deform the ground rail at some positions during the movement of the ground rail, the ground rail is divided into several small intervals, and the robot base is controlled to move from the starting point to the end point in these intervals. During the movement of the robot base, the robot tool end gradually moves away from the calibration point until the robot base moves to the end of the interval, and the base coordinate system coordinate information of the robot tool end is recorded. At the end of the interval, the robot tool end is controlled to reset to the calibration point, and the base coordinate system coordinate information of the robot tool end is recorded again, thereby obtaining the displacement information of the robot as a whole in space. In other words, when the ground rail is deformed, the direction of the displacement is at an angle with the extension direction of the ground rail, thereby obtaining the direction vector corresponding to the interval. Finally, the transformation relationship is obtained by combining the direction vector, displacement length, and interval length. Based on the position of the interval, the coordinate transformation relationship between the world coordinates of the robot tool end at each location of the ground rail and the base coordinates of the robot working end is determined.

[0015] In summary, by calibrating and compensating for each section, the influence of slight deformation of the ground rail caused by the robot was reduced, thereby controlling the movement error of the robot tool end within the allowable range.

[0016] Optionally, the step of obtaining the base movement information of the robot base from the starting point of the interval to the end point of the interval includes:

[0017] Get the encoder values ​​corresponding to the robot base at the start and end of the interval, and calculate the encoder difference as the base movement information.

[0018] Optionally, the step of obtaining reset stroke information of the end of the robot tool includes:

[0019] Obtaining first coordinate information corresponding to the robot at the end of the stroke and before resetting; wherein the first coordinate information is the coordinate in the base coordinate system;

[0020] Obtaining the second coordinate information corresponding to the robot at the end of the stroke and after resetting; wherein the second coordinate information is the coordinate in the base coordinate system;

[0021] The difference between the first coordinate information and the second coordinate information is calculated as the reset stroke information.

[0022] Optionally, the step of calculating the direction vector corresponding to each interval based on the reference information includes:

[0023] The ratio of the reset stroke information to the base movement information is calculated as the direction vector of the corresponding interval.

[0024] Optionally, the following steps are also included:

[0025] A subdivision step, further dividing the corresponding interval into several intervals based on the reference information;

[0026] After the refinement step, the manipulation step, the information acquisition step, the direction calculation step and the compensation calculation step are sequentially performed.

[0027] Optionally, the calibration point is fixed relative to the world coordinate system.

[0028] In the second aspect, the present application provides a control method for a bending robot with a ground rail, which adopts the following technical solution:

[0029] A control method for a bending robot with a ground rail comprises the following steps:

[0030] Based on the above multi-axis robot calibration method, a coordinated relationship between the robot tool end and the ground rail is established;

[0031] A workbench coordinate system is built based on the tool groove, wherein the workbench coordinate system takes the center point of the tool groove as the origin, the direction of the tool groove as the x-axis direction, and the up and down movement direction of the bending knife as the y-axis direction;

[0032] Control the robot to grab the sheet metal part and place it on the knife groove and wait for the bending to start;

[0033] Based on the bending signal, the end of the robot tool is controlled to grasp the sheet metal and rotate it along the x-axis of the workbench; wherein, when the bending signal is sent, the bending knife moves toward the knife groove, the rotation speed of the sheet metal is determined based on the pressing speed of the bending knife, and the maximum bending angle is determined based on the pressing depth of the bending knife, the groove depth and the groove width of the knife groove.

[0034] In a third aspect, the present application provides a multi-axis robot calibration system with a ground track, which adopts the following technical solution:

[0035] A multi-axis robot calibration system with a ground track, comprising:

[0036] The system building module is used to establish a base coordinate system based on the robot base and set calibration points based on the world coordinate system;

[0037] A zone division module is used to divide the moving path of the robot base into several zones;

[0038] A manipulation module, used to control the robot base to move from the starting point to the end point of each interval, and to control the robot tool end to reset to the calibration point at the end point of the interval, wherein the robot tool end is located at the calibration point when the robot base is located at the starting point of the interval; an information acquisition module, used to obtain the base movement information of the robot base from the starting point to the end point of the interval, and the corresponding reset stroke information of the robot tool end; wherein the base coordinate system coordinate information and the reset stroke information are used as reference information and correspond to the interval;

[0039] A direction calculation module, used to calculate the direction vector corresponding to each interval based on the reference information;

[0040] The compensation calculation module is used to determine the coordinate transformation relationship of each section of the ground rail with respect to the end of the robot tool in the base coordinate system based on the direction vector, section position and section length of each section.

[0041] In a fourth aspect, the present application provides an electronic device, which adopts the following technical solution:

[0042] An electronic device comprising:

[0043] one or more processors;

[0044] Memory;

[0045] one or more application programs, wherein the one or more application programs are stored in the memory and configured to be executed by the one or more processors, the one or more programs being configured to:

[0046] Execute the above-mentioned multi-axis robot calibration method with ground track;

[0047] And / or, executing the above-mentioned control method of the bending robot with ground rails.

[0048] In a fifth aspect, the present application provides a computer-readable storage medium, which adopts the following technical solution:

[0049] A computer-readable storage medium stores a computer program that can be loaded by a processor and execute the above method.

[0050] The storage medium stores at least one instruction, at least one program, a code set or an instruction set, and the at least one instruction, the at least one program, the code set or the instruction set is loaded and executed by the processor to implement:

[0051] The calibration method of a multi-axis robot with a ground track as described above;

[0052] And / or, the above-mentioned control method of the bending robot with ground rail.

[0053] In summary, the present application includes at least one of the following beneficial technical effects:

[0054] 1. The robot is installed on the ground rail, and the two are controlled collaboratively to expand the robot's working range and flexibly select the working position to prevent the robot from passing through unreachable strange positions.

[0055] 2. When there is a slight deformation of the ground rail that affects the positioning accuracy of the robot, the ground rail needs to be divided into multiple sections for coordinated control, which is conducive to controlling the accuracy within the allowable range.

[0056] 3. According to the downward pressure distance of the bending knife, control the robot to lift the sheet metal part and rotate it around the slot to achieve the bending effect of the sheet metal part. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 It is the logical connection relationship between the electronic device and the external device in a certain embodiment of the present application.

[0058] Figure 2 It is a flow chart of a calibration method for a multi-axis robot with a ground track in a certain embodiment of the present application.

[0059] Figure 3 It is a schematic diagram used to illustrate the relationship between the ground rail position and the coding value in a certain embodiment of the present application.

[0060] Figure 4-a , Figure 4-b , Figure 4-c It is a schematic diagram used to illustrate the movement of a robot within a range in a certain embodiment of the present application.

[0061] Figure 5 It is a schematic diagram used to illustrate the coordinate association of a robot in different coordinate systems in a certain embodiment of the present application.

[0062] Figure 6 It is a flow chart of a control method of a bending robot with a ground rail in a certain embodiment of the present application. DETAILED DESCRIPTION

[0063] The present application is further described in detail below in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0064] Figure 2 FIG. 1 is a flow chart of a calibration method for a multi-axis robot with a ground track in a certain embodiment. It should be understood that although Figure 2 The steps in the flowchart are shown in sequence as indicated by the arrows, but the steps are not necessarily executed in the order indicated by the arrows; unless otherwise specified in this document, there is no strict order restriction for the execution of the steps, and the steps may be executed in other orders; and Figure 2 At least part of the steps may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily executed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least part of the sub-steps or stages of other steps.

[0065] In addition, the numbers of the steps in this embodiment are only for convenience of explanation and do not limit the execution order of the steps. In practical applications, the execution order of the steps can be adjusted as needed, or performed simultaneously. These adjustments or replacements are all within the scope of protection of the present invention.

[0066] In the following description, for the purpose of explanation, many specific details are set forth in order to provide a thorough understanding of the inventive concept. As part of this specification, some of the drawings in the drawings of the present disclosure represent structures and devices in the form of block diagrams to avoid making the disclosed principles complicated and difficult to understand. For the sake of clarity, not all features of the actual implementation are necessary to be described. In addition, the language used in this disclosure has been selected primarily for readability and instructional purposes, and may not be selected to delineate or limit the subject matter of the present invention, thereby resorting to the necessary claims to determine such inventive subject matter. References to "a specific implementation" or "specific implementations" in this disclosure mean that the specific features, structures or characteristics described in conjunction with the specific implementation are included in at least one specific implementation, and multiple references to "a specific implementation" or "specific implementations" should not be understood as necessarily referring to the same specific implementation.

[0067] Unless expressly limited, the terms "a", "an", and "the" are not intended to refer to a singular entity, but rather to include general categories of which specific examples may be used for illustration. Thus, the use of the terms "a" or "an" may mean any number of at least one, including "one", "one or more", "at least one", and "one or more than one". The term "or" means any of the alternatives and any combination of the alternatives, including all alternatives, unless the alternatives are expressly indicated to be mutually exclusive. The phrase "at least one of" when combined with a list of items refers to a single item in the list or any combination of the items in the list. The phrase does not require all of the listed items unless expressly limited to that.

[0068] The robot base is installed on the ground rail and can slide left and right along the ground rail. The ground rail can expand the robot's working range. Without changing the robot's arm length, the robot can reach a larger range of positions. In addition, a fixed bending position may be in a strange position that the robot cannot reach. By changing the robot's position on the ground rail, while ensuring that the bending position remains unchanged, the robot's joints have more options and can flexibly avoid strange positions.

[0069] In different embodiments, a single ground rail can be one formed by integral casting of steel material, or one formed by splicing multiple steel materials. A single steel rail has the advantages of uniform strength and high flatness, while splicing multiple ground rails can overcome the disadvantage of insufficient length of a single ground rail. However, whether the ground rail is made of a complete steel material or spliced ​​by multiple materials, when the base supporting the robot slides, the entire track must be straight, so that the same direction vector is used when the robot tool end is transformed to the world coordinate system, that is, the calibrated direction is the same.

[0070] At present, for use scenarios with low precision requirements such as packaging, transportation, palletizing, and welding, the direction vectors along the length of the ground rail at various locations on the surface of the ground rail can be considered to be the same, and the robot can slide directly on the ground rail and use the same direction vector for coordinate transformation. For use scenarios such as high-precision processing, inspection, grasping, and installation, the accuracy loss is often required to be within ±0.5mm. For example, a bending machine is a machine that bends metal sheets. Currently, robots can be used to grab sheet metal parts during bending machine operations and place them in specific positions to cooperate with the bending machine to complete the bending. Bending operations have high requirements on the accuracy of robots. When the accuracy is insufficient, it is easy to cause sheet metal parts to be difficult to fit with other mating components, such as interference fit or clearance fit, resulting in reduced product yield.

[0071] In actual work, the following factors cause the accuracy of the ground rail to fail to meet the requirements:

[0072] (1) The machining accuracy of the rail itself is insufficient, or the rail itself is deformed by external influences. Since the rail material itself has slight deformations and is not smooth and straight, it is difficult to identify its defects from the appearance. For short-distance rails, this slight defect can be ignored, but if the local measured calibration direction is unified for each position of the long-distance rail, it is easy to cause the position of the two ends of the rail to deviate from the theoretical value.

[0073] (2) There is a local depression in the ground at the end of the rail. When there is a depression several millimeters deep in the ground at the head end of the rail, the rail is suspended relative to the ground at the depression. The robot usually weighs hundreds of kilograms or even tons. When the robot slides to the head end of the rail, the head end of the rail will bend downward under the pressure of the robot, which is commonly known as being bent. When the robot slides to the end of the rail, the pressure on the head end of the rail will be released, and the deformation will be restored accordingly, which is commonly known as tilting. In this way, there is a slight difference between the actual direction of the rail and the actual direction, and this difference cannot be ignored under high precision requirements.

[0074] (3) There is a gap between the middle of the track and the ground. This gap may be caused by a depression on the bottom of the track or a depression of several millimeters on the ground. When the robot slides to this place, the track will be compressed and deformed, and the robot will sink. When the robot leaves, the track returns to its original state. Similarly, in this case, there will be a slight difference between the direction of the track and the actual direction.

[0075] Therefore, in order to solve this type of problem, laser calibration instruments are used in related technologies for auxiliary calibration. Specifically, a feature block is fixedly set on the robot base or articulated arm, and the installation position of the feature block remains unchanged in the robot base coordinate system during the movement of the robot, and feature points are set on the feature block. Any preset point in the world coordinate system is recorded as the reference position, and the position of the feature point in the world coordinate system is taken as the reference position. At the reference position, a laser calibration instrument is used to obtain the robot external parameter T0; at the reference position, the translation matrix between the reference position and the reference position is first obtained, and then the translation matrix is ​​applied to T0 to obtain the robot external parameter at the reference position. The external parameter matrix of each point can be obtained through the translation matrix corresponding to each reference position without relying on the absolute accuracy of the ground track.

[0076] Although this solution is highly feasible, it actually relies on the high precision of the laser calibration instrument to make up for the accuracy problem of the ground track. Currently, the price of robots on the market is usually more than 100,000 yuan, and the lowest is only as low as tens of thousands of yuan, while the laser calibration instrument can cost hundreds of thousands of yuan depending on the accuracy. For ordinary users, its relative cost is too high and unaffordable.

[0077] When the robot causes slight deformation of the ground rail, the movement error of the robot tool end can be controlled within the allowable range at a low cost. The embodiment of the present application discloses an electronic device and a calibration method for a multi-axis robot with a ground rail based on the electronic device. The robot is a working device with multiple degrees of freedom. The action output end of the robot is the tool end, which can perform processing operations on the workpiece, such as a milling cutter, a spray gun, a pressing block, etc. Figure 1 As shown, the electronic device is used to control the end of the tool. Specifically, the electronic device includes at least: a processor and a memory. The processor and the memory are connected, such as through a bus. In different embodiments, the electronic device may also include a command input device and / or an image output system. It should be noted that the structure of the robot does not constitute a limitation on the electronic device and the motion path planning method in this application.

[0078] The processor may be a CPU (Central Processing Unit), a general-purpose processor, a DSP (Digital Signal Processor), an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array) or other programmable logic devices, transistor logic devices, hardware components or any combination thereof. It may implement or execute various exemplary logic blocks, modules and circuits described in conjunction with the disclosure of this application. The processor may also be a combination that implements computing functions, such as a combination of one or more microprocessors, a combination of a DSP and a microprocessor, etc. In some cases, the processor may also be replaced by a cloud server.

[0079] The bus may include a path to transmit information between the above components. The bus may be a PCI (Peripheral Component Interconnect) bus or an EISA (Extended Industry Standard Architecture) bus. The bus may be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 1 Only one thick line is used in the diagram, but this does not mean that there is only one bus or only one type of bus.

[0080] The memory may be a ROM (Read Only Memory) or other types of static storage devices that can store static information and instructions, a RAM (Random Access Memory) or other types of dynamic storage devices that can store information and instructions, or an EEPROM (Electrically Erasable Programmable Read Only Memory), a CD-ROM (Compact Disc Read Only Memory) or other optical disk storage, optical disk storage (including compressed optical disk, laser disk, optical disk, digital versatile optical disk, Blu-ray disk, etc.), a disk storage medium or other magnetic storage device, or any other medium that can be used to carry or store the desired program code in the form of an instruction or data structure and can be accessed by a computer, but is not limited thereto. In some cases, the processor may also be replaced by a cloud storage. It should be noted that in the present robot, the memory includes at least a random access memory as a cache area.

[0081] The memory is used to store the application code for executing the solution of the present application, and the execution is controlled by the processor. The processor is used to execute the application code stored in the memory to implement the content shown in the above method embodiment.

[0082] The command input device can be an action signal input device such as an operating handle, a touch pad, a mouse, a keyboard, etc., for receiving action commands such as keystrokes; it can also be an image input device such as a camera, a CCD, etc., for receiving image commands such as gestures and teaching samples; it can also be an audio input device such as a microphone, an intercom, a mobile phone, etc., for receiving voice commands. The command input processor can obtain relevant data and store it in the memory.

[0083] The image output system can be a CRT display (Cathode Ray Tube), LED screen (light-emitting diode), LCD display (Liquid Crystal Display), OLED screen (Organic Light Emitting Diode), projector or other types of displays, as long as it can display the operation interface, the operation interface is used to indicate the process of command input and the input result to the operator, or to provide interactive instructions. It should be noted that in actual applications, the command input device and / or image output system is not limited to one.

[0084] Among them, electronic devices include but are not limited to: mobile terminals such as mobile phones, laptops, digital broadcast receivers, PDAs (personal digital assistants), PADs (tablet computers), PMPs (portable multimedia players), vehicle-mounted terminals (such as vehicle-mounted navigation terminals), etc., and fixed terminals such as digital TVs, desktop computers, etc. Figure 1 The electronic device shown is merely an example and should not bring any limitation to the functions and scope of use of the embodiments of the present application.

[0085] Reference Figure 2 , the calibration method of the multi-axis robot with ground rails includes the following steps:

[0086] S1. System building steps: Establish a base coordinate system based on the robot base, and set calibration points based on the world coordinate system.

[0087] Since the ground track is fixed on the ground, it is convenient to use the world coordinate system to represent the spatial position of each point on the ground track. Figure 3 , Point P1 and Point P2 in the figure are two points on the ground track, and Point P1 and Point P2 are coordinate points in the world coordinate system.

[0088] Although the robot base has a certain volume, the relative position between the fixed point on the robot and the connection point between the robot and the ground rail is unchanged. Therefore, when a base coordinate system is established with a fixed point on the robot base as the origin, the position of the origin in the world coordinate system can be transformed to the ground rail through a certain transformation relationship. For the convenience of description, in the embodiment of the present application, the origin of the base coordinate system is regarded as moving on the ground rail, such as falling on points P1 and P2 in the figure.

[0089] E1 is the encoder value corresponding to point P1, and E2 is the encoder value corresponding to point P2. From the above background, it can be seen that points P1 and P2 may not be located on the extension line of the same ground track length due to the pressure of the robot base, such as not being located at the same horizontal height. The encoder values ​​E1 and E2 can be used to represent the horizontal positions of points P1 and P2.

[0090] Since the tool end of the robot usually moves around the robot base, establishing a base coordinate system with a fixed point on the robot base as the origin can conveniently describe the spatial position of the robot tool end. The control system can also save a lot of transformation operations generated by the movement between world coordinate points, thereby improving the utilization of the machine computing power.

[0091] In addition, a calibration point is set in the world coordinate system, that is, the calibration point is a fixed point in the world coordinate system. The calibration point is used to provide a spatial reference for the working end of the robot, thereby establishing a connection between an unknown base coordinate system point and a known world coordinate system point. As an example, the calibration point can be the tip of a calibration rod fixedly erected on the ground and located on one side of the ground rail. When using it, it is not necessary to know the world coordinates of the calibration point, so the selection of the calibration point is arbitrary.

[0092] S2. Zoning step: dividing the moving path of the robot base into several sections.

[0093] During the movement of the robot base on the ground rail, the ground rail may be slightly deformed at some positions, and the naked eye cannot determine whether it is deformed. Specifically, the actual position of the robot base deviates from the theoretically calculated position, and this deviation affects the positioning accuracy or bending accuracy. Therefore, multi-segment calibration is required, that is, the ground rail is divided into several small intervals, and the robot base is controlled to move from the starting point to the end point in these intervals. Here, each area is equivalently replaced by a straight line segment, so that a bend can be divided into multiple straight lines, that is, multiple areas. One area needs to calibrate two points, two consecutive areas need to calibrate three points, three consecutive areas need to calibrate four points, and so on.

[0094] It should be noted that the division of intervals needs to be continuous and complete, and the range of motion of the robot base on the ground rail should be divided into intervals. The division of intervals can be understood as the micro-elementization of the ground rail, so the length of the interval should be appropriately small and should be close to the average linear dimension of the deformation. In addition, the demarcation step size of different intervals can be the same or different, and can be set based on actual needs, and this embodiment does not limit it.

[0095] S3. Operation steps: control the robot base to move from the starting point to the end point of each interval, and control the robot tool end to reset to the calibration point at the end point of the interval, wherein the robot tool end is located at the calibration point when the robot base is located at the starting point of the interval.

[0096] The robot base can move along each interval in sequence, or can move separately in different intervals. In some embodiments, for the convenience of operation, the robot base can move along the ground track with a fixed step length, and the moving path within each step length range is regarded as an interval, and the encoder values ​​corresponding to the interval start point and the interval end point are recorded. Through this method, the encoder value corresponding to the end point position of the previous interval is the encoder value corresponding to the start point position of the next interval.

[0097] Specifically, refer to Figure 4-a , Figure 4-b , Figure 4-cThe solid origin in the figure is used to indicate the calibration point, the square is used to indicate the robot base, the broken line on the top of the square is used to indicate the end of the robot arm and the tool, the horizontal line at the bottom of the square is used to indicate the ground track, and points P1 and P2 are used to indicate the starting point and end point of the interval. Figure 4-a In the figure, the robot base is located at the starting point P1 of the interval, and the end of the tool abuts against the calibration point. Figure 4-b In the figure, the robot base moves to the end point P2 of the interval, and the tool end moves together with the robot base. The moving path of the tool end is P1P2, and the actual value of the moving path is unknown at this time. Figure 4-c In the example, the tool end is reset to the calibration point under the control of the console. At this time, the moving path of the tool end is P1P2. Since it is controlled by the console, the direction vector is a known quantity. It should be noted that the resetting process of the tool end can be manually controlled or automatically reset based on computer vision control. Any method that can know the movement path of the tool end is acceptable and is not specifically limited in this solution.

[0098] S4. Information acquisition step: acquiring the base movement information of the robot base from the starting point of the interval to the end point of the interval, and the corresponding reset stroke information of the end of the robot tool; wherein the base coordinate system coordinate information and the reset stroke information are used as reference information and correspond to the interval.

[0099] Specifically, step S4 includes the following steps:

[0100] S41. Obtain the encoder values ​​corresponding to the robot base at the start and end of the interval, and calculate the encoder difference as the base movement information.

[0101] The encoder difference ΔE between points P1 and P2 is equivalent to the horizontal projection length of the spatial line between points P1 and P2:

[0102] ΔE=E1-E2

[0103] S42. Obtaining the first coordinate information corresponding to the robot at the end of the travel and before resetting; wherein the first coordinate information is the coordinate in the base coordinate system;

[0104] S43. Obtaining the second coordinate information corresponding to the robot at the end of the travel and after resetting; wherein the second coordinate information is the coordinate in the base coordinate system;

[0105] S44. Calculate the difference between the first coordinate information and the second coordinate information as reset stroke information.

[0106] The reset stroke information is the coordinate distance length between point P1 and point P2, that is, the actual length of the spatial connection between the two points:

[0107] length=|P1P2|

[0108] S5. Direction calculation step: Calculate the direction vector corresponding to each interval based on the reference information.

[0109] In this step, the ratio of the reset stroke information to the base movement information is calculated as the direction vector of the corresponding interval. For example, the ratio of the vector from point P1 to point P2 to the scalar is the unit direction vector from point P1 to point P2:

[0110]

[0111] The encoder difference and position increment are proportional:

[0112]

[0113] The unit vector from point P1 to point P2 is multiplied by the ratio to obtain the corrected direction vector, that is, the calibrated direction vector:

[0114] Multiply the unit vector at point P1 and point P2 by the ratio to obtain the corrected direction vector, that is, the calibrated direction vector:

[0115]

[0116] S6. Compensation calculation step: Based on the direction vector, interval position and interval length of each interval, determine the coordinate transformation relationship between the world coordinates of the robot tool end and the base coordinates of the robot working end for each interval of the ground rail.

[0117] Specifically, refer to Figure 5 In the figure, A is in the world coordinate system O, and its coordinates are P E . A is in the base coordinate system B, and its coordinates are P T . B is in the world coordinate system O, and its coordinates are P B . Take the following calculation process as an example.

[0118] Set the coordinates of the robot base to P r , after moving to P r +ΔP. Where P r is the world coordinate.

[0119] The coordinates of the robot tool end are P E , after moving to P E Among them, P E and P E ` is the world coordinate, and P E ` is an unknown quantity.

[0120] When the robot base moves, the coordinates of the robot base are changed from P r becomes:

[0121] P r +ΔP ①

[0122] Since the robot tool end returns to the calibration point before and after the movement,

[0123] P E `==P E ②

[0124] Since the position of the robot tool end has not changed, but the position of the robot base has changed, it means that the overall joint relationship of the robot has changed. From ①②, we can see that

[0125] P T ≠P T ` ③

[0126] Therefore, according to the above information, P T `.

[0127] P T ` is the coordinate of the robot tool end relative to the base, so we only need to know the world coordinate P of the base B and the robot tool end coordinate P E That's it.

[0128] P B =P r +ΔP ④

[0129] And P E Known, the problem is transformed into finding ΔP:

[0130]

[0131] in is obtained by calibration, and ΔE is given by the user.

[0132] Substituting ⑤ into ④, we get

[0133]

[0134] Therefore, P T =T(P B ) -1 ·P E , that is, P E Relative to P B The coordinates of .

[0135] That is to say, since the correspondence between the world coordinates of the robot tool end at each location of the ground rail and the base coordinates of the robot working end is determined, the corresponding transformation matrix can be obtained to conveniently describe the correspondence, rather than using the direction vector method, which is more in line with computer program design. In addition, since the deformation positions of the ground rail are limited and few, that is, the transformation matrices corresponding to most locations of the ground rail are actually the same, and the transformation matrices of a few locations are different, so the space requirement for the memory is also small.

[0136] In addition, optionally, in some embodiments, a refinement step may be performed after the zoning step, and the refinement step is to divide the corresponding interval into several intervals based on the reference information, and then sequentially perform the manipulation step, the information acquisition step, the direction calculation step and the compensation calculation step after the refinement step. This step can divide some steeper bending defects into multiple segments, so that a single bending defect is described by more direction vectors, so that the change compensation is more accurate. The determination of the curvature size here can be obtained by the above-mentioned ratio.

[0137] The present application also discloses a multi-axis robot calibration system with a ground track, comprising:

[0138] The system building module is used to establish a base coordinate system based on the robot base and set calibration points based on the world coordinate system;

[0139] A zone division module is used to divide the moving path of the robot base into several zones;

[0140] A manipulation module, used to control the robot base to move from the starting point to the end point of each interval, and to control the robot tool end to reset to the calibration point at the end point of the interval, wherein the robot tool end is located at the calibration point when the robot base is located at the starting point of the interval; an information acquisition module, used to obtain the base movement information of the robot base from the starting point to the end point of the interval, and the corresponding reset stroke information of the robot tool end; wherein the base coordinate system coordinate information and the reset stroke information are used as reference information and correspond to the interval;

[0141] A direction calculation module, used to calculate the direction vector corresponding to each interval based on the reference information;

[0142] The compensation calculation module is used to determine the coordinate transformation relationship of each section of the ground rail with respect to the end of the robot tool in the base coordinate system based on the direction vector, section position and section length of each section.

[0143] The present application also discloses an electronic device, including a memory and a processor, wherein the memory stores a computer program that can be loaded by the processor and executes the multi-axis robot calibration method with a ground track as described above. The execution subject of the method of this embodiment can be a control device, which is arranged on an electronic device. The current device can be an electronic device such as a mobile phone, a tablet computer, a laptop computer, etc. with a WIFI function. The execution subject of the method of this embodiment can also be directly a CPU (central processing unit) of the electronic device.

[0144] The embodiment of the present application also discloses a computer-readable storage medium, which stores a computer program that can be loaded by a processor and execute the multi-axis robot calibration method with a ground rail as above. Through the description of the above implementation mode, those skilled in the art can clearly understand that the above-mentioned embodiment method can be implemented by means of software plus a necessary general hardware platform, and of course it can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product is stored in a storage medium (such as ROM / RAM, disk, CD) as above, including a number of instructions to enable a device (which can be a mobile phone, computer, server, controlled terminal, or network device, etc.) to execute the method of each embodiment of the present application.

[0145] Reference Figure 6 The present application also discloses a control method for a bending robot with a ground rail, comprising the following steps:

[0146] Step 1: Establish the coordination relationship between the robot tool end and the ground rail based on the above-mentioned multi-axis robot calibration method;

[0147] Step 2: Build a workbench coordinate system based on the tool groove, where the workbench coordinate system takes the center point of the tool groove as the origin, the direction of the tool groove as the x-axis direction, and the up and down movement direction of the bending knife as the y-axis direction;

[0148] Step 3: Control the robot to grab the sheet metal part and place it on the knife groove and wait for the bending to start;

[0149] Step 4: Based on the bending signal, the end of the robot tool is controlled to grab the sheet metal and rotate it along the x-axis of the workbench; wherein, when the bending signal is issued, the bending knife moves toward the knife groove, the rotation speed of the sheet metal is determined based on the pressing speed of the bending knife, and the maximum bending angle is determined based on the pressing depth of the bending knife, the groove depth and the groove width of the knife groove.

[0150] In a specific embodiment, the system first controls the robot to pick up the sheet metal parts from the loading rack and place the sheet metal parts on the preparation rack. The system will give a control signal to start the adjustment device on the preparation rack. After the adjustment device is started, the position of the sheet metal parts on the preparation rack will be corrected, so that the robot can grab the designated position of the sheet metal parts for bending every time.

[0151] The robot grabs and moves the sheet metal parts through pre-set movements until it reaches the bending knife. During this process, the robot moves back and forth on the ground rails. The system uses the transformation matrix obtained by the multi-axis robot calibration method mentioned above to compensate for the displacement of the robot tool end when passing through some deformation positions, thereby achieving a precise control effect.

[0152] According to the change of the bending blade downward pressure distance or the grating ruler pulse, the robot is controlled to follow the bending. In this process, the robot does not actively push the sheet metal to bend, but the sheet metal deforms as it bends, and the part of the sheet metal exposed outside the bending machine will tilt upward. The robot moves synchronously and does not add additional push and pull forces to the sheet metal.

[0153] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A calibration method for a multi-axis robot with a ground track, characterized in that: The following steps are involved: System building step: establishing a base coordinate system based on the robot base and setting calibration points based on the world coordinate system; A zone division step, dividing the moving path of the robot base into several zones; The operation step is to control the robot base to move from the starting point to the end point of each interval, and control the robot tool end to reset to the calibration point at the end point of the interval, wherein the robot tool end is located at the calibration point when the robot base is located at the starting point of the interval; An information acquisition step, acquiring base movement information of the robot base from the starting point of the interval to the end point of the interval, and reset stroke information of the corresponding robot tool end; wherein the base coordinate system coordinate information and the reset stroke information are used as reference information and correspond to the interval; A direction calculation step, calculating the direction vector corresponding to each interval based on the reference information; The compensation calculation step is to determine the coordinate transformation relationship between the world coordinates of the robot tool end and the base coordinates of the robot working end of each section of the ground rail based on the direction vector, section position and section length of each section. The step of obtaining the base movement information of the robot base from the starting point of the interval to the end point of the interval includes: Get the encoder values ​​corresponding to the robot base at the start and end of the interval, and calculate the encoder difference as the base movement information. The step of obtaining the reset stroke information of the end of the robot tool comprises: Obtaining first coordinate information corresponding to the robot at the end of the stroke and before resetting; wherein the first coordinate information is the coordinate in the base coordinate system; Obtaining the second coordinate information corresponding to the robot at the end of the stroke and after resetting; wherein the second coordinate information is the coordinate in the base coordinate system; Calculate the difference between the first coordinate information and the second coordinate information as reset stroke information, The step of calculating the direction vector corresponding to each interval based on the reference information includes: The ratio of the reset stroke information to the base movement information is calculated as the direction vector of the corresponding interval.

2. The calibration method according to claim 1, characterized in that: The following steps are also included: A subdivision step, further dividing the corresponding interval into several intervals based on the reference information; After the refinement step, the manipulation step, the information acquisition step, the direction calculation step and the compensation calculation step are sequentially performed.

3. The calibration method according to claim 1, characterized in that: The calibration points are fixed relative to the world coordinate system.

4. A control method for a bending robot with a ground rail, characterized in that: The following steps are involved: Establishing a collaborative relationship between the robot tool end and the ground rail based on the multi-axis robot calibration method as described in any one of claims 1 to 3; A workbench coordinate system is built based on the tool groove, wherein the workbench coordinate system takes the center point of the tool groove as the origin, the direction of the tool groove as the x-axis direction, and the up and down movement direction of the bending knife as the y-axis direction; Control the robot to grab the sheet metal part and place it on the knife groove and wait for the bending to start; Based on the bending signal, the end of the robot tool is controlled to grasp the sheet metal and rotate it along the x-axis of the workbench; wherein, when the bending signal is sent, the bending knife moves toward the knife groove, the rotation speed of the sheet metal is determined based on the pressing speed of the bending knife, and the maximum bending angle is determined based on the pressing depth of the bending knife, the groove depth and the groove width of the knife groove.

5. An electronic device, characterized in that: It includes: one or more processors; Memory; one or more application programs, wherein the one or more application programs are stored in the memory and configured to be executed by the one or more processors, the one or more programs being configured to: Execute the calibration method of a multi-axis robot with a ground track according to any one of claims 1 to 3; And / or, executing the control method of the bending robot with ground rail according to claim 4.

6. A computer-readable storage medium, characterized in that: The storage medium stores at least one instruction, at least one program, a code set or an instruction set, and the at least one instruction, the at least one program, the code set or the instruction set is loaded and executed by the processor to implement: The calibration method of a multi-axis robot with a ground track as claimed in any one of claims 1 to 3; And / or, the control method of a bending robot with a ground rail as described in claim 4.

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