CN117754591A - Calibration method, calibration device and calibration system - Google Patents
Calibration method, calibration device and calibration system Download PDFInfo
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Abstract
The application discloses a calibration method, a calibration device and a calibration system, which are used for calibrating calibration position coordinates of a center point of an actuator installed on a manipulator under a flange coordinate system of the manipulator, wherein the method comprises the following steps: when a contact probe of the contact detection device contacts each contact of the target plane, the target pose of the manipulator is acquired, the contact detection device is arranged on the flange, the position of the contact probe coincides with the center point of the actuator, and the contact detection device is used for sending prompt information when the contact probe contacts the target plane; according to the standard positions and postures corresponding to the contacts, respectively calculating the position and posture conversion relation between the manipulator coordinate system and the flange coordinate system corresponding to the standard positions and postures; and calculating the coordinate of the calibration position according to the pose conversion relation corresponding to each calibration pose and the coplanarity relation of each contact. The accuracy of the obtained calibration pose of the manipulator can be improved, so that the accuracy of a calibration result is improved; the problems that accurate touch is difficult to realize under the conditions of human eye observation and manual control are avoided, and the calibration efficiency is improved.
Description
Technical Field
The present application relates to the field of robotic arms, and more particularly, to a calibration method, a calibration device, and a calibration system.
Background
The traditional TCP calibration method (Total Convolutional Profile, TCP) is a four-point method or a six-point method (parameters are estimated through a plurality of known points on an object) for aligning a calibration needle point, the operation point of an end effector of a manual operation control manipulator touches the calibration needle point in 4 or more different postures to calibrate, in the calibration process, whether the operation point is aligned to the needle point needs to be judged by human eyes, the operation difficulty is high, the human eye observation precision is limited, the precision of TCP calibration is low, and the actual operation precision is influenced.
Disclosure of Invention
The embodiment of the application provides a calibration method, a calibration device, a calibration system, computer equipment and a nonvolatile computer readable storage medium. The calibration position coordinates of the center of the actuator under the flange coordinate system can be accurately calibrated according to the pose conversion relations corresponding to the target poses and the accurate coplanarity relations of the contacts, and TCP calibration is completed.
The calibration method of the embodiment of the application is used for calibrating the calibration position coordinates of the center point of the actuator arranged on the manipulator under the flange coordinate system of the manipulator, and comprises the following steps: when a contact probe of a contact detection device contacts each contact of a target plane (a calibration plate), the contact detection device is arranged on the flange, the position of the contact probe coincides with the center point of the actuator, and the contact detection device is used for sending prompt information when the contact probe contacts the target plane; according to the positioning pose corresponding to each contact, respectively calculating pose conversion relations between a manipulator coordinate system and a flange coordinate system corresponding to each positioning pose; and calculating the calibration position coordinates according to the pose conversion relation corresponding to each calibration pose and the coplanarity relation of each contact.
In some embodiments, the positioning pose includes a position coordinate and a pose angle, the pose conversion relationship includes a translation matrix and a rotation matrix, and the calculating the pose conversion relationship corresponding to each positioning pose according to the positioning pose corresponding to each contact includes: calculating a translation matrix corresponding to the calibration gesture according to the position coordinates of the calibration gesture; and calculating a rotation matrix corresponding to the calibration gesture according to the gesture angle of the calibration gesture.
In some embodiments, the calculating the calibration position coordinate according to the pose conversion relationship corresponding to each calibration pose and the coplanarity relationship of each contact includes: establishing a first functional relation between the calibration position coordinates and the contact coordinates of each contact under a manipulator coordinate system according to the pose conversion relation corresponding to each calibration pose; establishing a second functional relationship between a normal vector of the target plane and the contact coordinates of any three non-collinear contacts; establishing a third functional relation of the normal vector and a contact vector formed by any two contact coordinates based on the coplanarity relation of all the contacts; and calculating the calibration position coordinates based on the first functional relation, the second functional relation and the third functional relation.
In some embodiments, the number of contacts is 6, and the 3 contacts that calculate the normal vector are different from the contacts that form the contact vector.
In some embodiments, the calculating the calibration location coordinates based on the first functional relationship, the second functional relationship, and the third functional relationship includes: according to the physical size of the actuator, determining initial position coordinates of a center point of the actuator when the center point of the actuator is mounted on the flange; and calculating the calibration position coordinate based on a preset nonlinear solving algorithm, the initial position coordinate, the first functional relation, the second functional relation and the third functional relation.
In certain embodiments, further comprising: calculating the predicted coordinates of each contact under a manipulator coordinate system according to the pose conversion relation corresponding to each target pose and the calibrated position coordinates; calculating root mean square error of the distance between the predicted coordinates corresponding to each contact point and the target plane; under the condition that the root mean square error is smaller than a preset error, determining that the calibration of the calibration position coordinates is completed; and under the condition that the root mean square error is larger than a preset error, taking the calibrated position coordinate as the initial position coordinate, and re-entering a step of calculating the calibrated position coordinate based on a preset nonlinear solving algorithm, the initial position coordinate, the first functional relation, the second functional relation and the third functional relation.
In some embodiments, there are at least 3 contacts that are not collinear among the contacts.
In some embodiments, the contact detection device comprises a sphere bar instrument comprising a mounting portion, a probe disposed at the mounting portion, and a contact probe disposed at an end of the probe distal from the mounting portion.
The calibration device of the embodiment of the application is used for calibrating the calibration position coordinates of a center point of an actuator installed on a manipulator under a flange coordinate system of the manipulator, and the device comprises: the acquisition module is used for acquiring the target position pose of the manipulator when a contact probe of the contact detection device contacts each contact of a target plane (a calibration plate), the contact detection device is arranged on the flange, the position of the contact probe coincides with the center point of the actuator, and the contact detection device is used for sending prompt information when the contact probe contacts the target plane; the first calculation module is used for calculating pose conversion relations between a manipulator coordinate system and a flange coordinate system corresponding to each target pose according to the target poses corresponding to each contact; and the second calculation module is used for calculating the calibration position coordinates according to the pose conversion relation corresponding to each calibration pose and the coplanarity relation of each contact.
The calibration system of the embodiment of the application comprises a calibration position coordinate used for calibrating a center point of an actuator installed on a manipulator under a flange coordinate system of the manipulator, and the calibration system comprises: a calibration device comprising a target plane; the contact detection device is arranged on the flange, the position of the contact probe is coincident with the center point of the actuator, and the contact detection device is used for sending out prompt information when the contact probe contacts the target plane; and the processor is used for executing the calibration method according to any embodiment.
The computer device of the embodiment of the application comprises a processor and a memory; and a computer program stored in the memory and executed by the processor, the computer program including instructions for performing the calibration method of any of the above embodiments.
The non-transitory computer readable storage medium containing a computer program according to an embodiment of the present application, when executed by a processor, causes the processor to execute the calibration method according to any one of the above embodiments.
According to the calibration method, the calibration device, the calibration system, the computer equipment and the nonvolatile computer readable storage medium, when the contact probe of the contact detection device contacts each contact of the target plane, the calibration pose of the manipulator is obtained, compared with the operation and observation of human eyes, the manipulator contacts each contact of the target plane, the force during contact is difficult to master, the contact position is deformed, the calibration accuracy is reduced, the contact detection of each contact is realized through the contact probe of the contact detection device, and a prompt is sent when the contact probe just contacts each contact, so that the accurate contact detection of the contact probe and each contact is realized.
And then according to the calibration positions and postures corresponding to the contacts, respectively calculating the position and posture conversion relation between the manipulator coordinate system and the flange coordinate system corresponding to the calibration positions and postures, and finally, according to the position and posture conversion relation corresponding to the calibration positions and postures and the accurate coplanarity relation of the contacts, accurately calibrating the calibration position coordinates of the center of the actuator under the flange coordinate system, and completing TCP calibration.
Additional aspects and advantages of embodiments of the application will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of embodiments of the application.
Drawings
The foregoing and/or additional aspects and advantages of the present application will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings, in which:
FIG. 1 is a schematic illustration of an application scenario of a calibration method according to certain embodiments of the present application;
FIG. 2 is a flow chart of a calibration method of certain embodiments of the present application;
FIG. 3 is a flow chart of a calibration method of certain embodiments of the present application;
FIG. 4 is a flow chart of a calibration method of certain embodiments of the present application;
FIG. 5 is a flow chart of a calibration method of certain embodiments of the present application;
FIG. 6 is a flow chart of a calibration method of certain embodiments of the present application;
FIG. 7 is a flow chart of a calibration method of certain embodiments of the present application;
FIG. 8 is a block schematic diagram of a calibration device according to certain embodiments of the present application;
FIG. 9 is a schematic structural diagram of a computer device according to some embodiments of the present application;
FIG. 10 is a schematic diagram of a connection state of a non-volatile computer readable storage medium and a processor according to some embodiments of the present application.
Detailed Description
Embodiments of the present application are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are exemplary only for explaining the embodiments of the present application and are not to be construed as limiting the embodiments of the present application.
To facilitate an understanding of the present application, the following description of terms appearing in the present application will be provided:
1. mechanical arm: an industrial robot having a structure and function similar to that of a human arm, which is composed of a plurality of joints and connectors, can perform various tasks and actions in a three-dimensional space.
2. TCP scaling method (Total Convolutional Profile, TCP): the mapping relation from the pixel coordinate system of the three-dimensional object surface to the world coordinate system is generally that in a three-dimensional space, there is a one-to-one correspondence relation between the pixel coordinate of the object surface and the coordinate in the world coordinate system.
3. Club instrument: a contact sensor with a precise sphere at the tail end sends out photoelectric prompt signals after the sphere contacts an object to be measured, is often used for CNC processing technology (Computer Numerical Control, CNC) for controlling a machine tool to process through a computer numerical control system, and is used for searching edges and setting tools on a workpiece before CNC processing, and the precision of a ball rod instrument or an edge searching instrument, a contact probe and a photoelectric center rod is generally higher and can reach 1um precision. When the TCP calibration method is used for calibration, if the cue instrument probe is installed to an actual working point, the action of referring to the center point of a tool of the end effector of the manipulator can be achieved.
4. Gauss-Newton iteration (Gauss-Newton iteration method, GN): an iterative method for solving regression parameters in a nonlinear regression model to carry out least square.
5. Levenberg-marquaret (LM): an estimation method of regression parameter least square estimation in nonlinear regression.
Along with the arrival of the intelligent manufacturing age, the 3D vision guiding technology is widely applied to industries such as automobiles, 3C, logistics, food and medicines, and the like, and conventional operation tasks such as picking, welding, stacking, mounting, dispensing, high-precision assembly and the like can be accurately controlled by a vision guiding manipulator technology, so that the labor cost is greatly reduced while the productivity of a production line is improved. The origin of the six-axis manipulator tool coordinate system is located at the center of the flange, and for different work tasks, different end effectors are required to be installed, and in actual use, tool center point calibration (Tool Center Point Calibration) needs to be performed first, namely, the transformation relation of a new tool coordinate system relative to the base world coordinate system is determined.
The traditional TCP calibration method is to use a four-point method (or six-point method) for calibrating needle point alignment to measure the position of a central point (TCP) of a robot tool, when the four-point method (or six-point method) is used, the central point of an end effector of a manipulator is generally controlled by manual operation to touch the calibrated needle point in 4 or more different postures for calibration, in the calibration process, whether the central point is aligned with the needle point needs to be determined by using human eyes, because fine adjustment is needed, the operation difficulty is high, the human eye observation precision is limited, the precision of TCP calibration is not high, and the precision and the calibration efficiency of actual operation are affected.
In order to solve the technical problems, an embodiment of the present application provides a calibration method.
The application scenario of the calibration method is described below, as shown in fig. 1, and the calibration method provided in the application scenario shown in fig. 1 can be applied. The calibration method is applied to a calibration system 1000, the calibration system 1000 is used for calibrating calibration position coordinates of a center point of an actuator mounted on a manipulator 400 in a flange coordinate system of the manipulator 400, and the calibration system 1000 includes a calibration device 100, a contact detection device 200, and a processor (not shown in the figure).
Alternatively, the calibration device comprises a target plane 100, the target plane 100 being used for the contact detection device 200, the target plane 100 may be an object plane with high precision flatness, such as a calibration plate, a ceramic plate, a measuring table marble plate, etc.
Optionally, the contact detection device 200 includes a cue instrument 200, where the cue instrument 200 includes a mounting portion 203, a probe 201, and a contact probe 202, where the probe 201 is disposed at the mounting portion 203, and the contact probe 202 is disposed at an end of the probe 201 away from the mounting portion 203, and the contact probe 202 sends a prompt message when contacting the grip plane 100.
The calibration method of the present application will be described in detail below:
referring to fig. 1 and 2, an embodiment of the present application provides a calibration method, which is applied to a center point of an actuator installed on a manipulator, and is described by taking a calibration position coordinate under a flange coordinate system of the manipulator as an example, and the calibration method includes:
step 011: when a contact probe of the contact detection device contacts each contact of the target plane, the target pose of the manipulator is acquired, the contact detection device is arranged on the flange, the position of the contact probe coincides with the center point of the actuator, and the contact detection device is used for sending prompt information when the contact probe contacts the target plane;
wherein the contact includes a plurality of contacts; the target plane may be a calibration plate; the contact detection device is used for sending prompt information when the contact probe contacts the target plane, and can be any device for providing tactile feedback when the contact probe contacts the calibration plate, such as a tactile sensor and the like, the contact detection device is arranged on a flange of the manipulator, the contact detection device comprises the contact probe, and the position of the contact probe coincides with the center point of the actuator.
Optionally, the contact detection device comprises a cue instrument, the cue instrument comprises a mounting portion, a probe and a contact probe, the probe is arranged on the mounting portion, and the contact probe is arranged at one end of the probe away from the mounting portion.
Specifically, the contact detection device comprises a ball arm instrument, the ball arm instrument comprises a mounting part, a probe and a contact probe, the probe is arranged on the mounting part, and the contact probe is arranged at one end of the probe far away from the mounting part. Because the contact probe of the cue instrument is very small, when the cue instrument is installed, the contact probe of the cue instrument can be overlapped with the center point of the manipulator actuator to play a role in referring to the center point of the manipulator actuator, so that the calibration accuracy is improved.
And under the condition that the contact probe of the cue instrument contacts each contact point of the target plane, acquiring the positioning pose of the manipulator under each contact point. When the manipulator touches different contacts, the actuator of the manipulator has different positions and postures, namely different postures. And controlling the contact probes of the ball arm instrument arranged on the flange of the manipulator to touch all the contacts on the target plane by controlling the movement of the manipulator, and recording the pose information of the manipulator under each contact. When the contact probe touches the target plane, prompt information is sent out, whether the contact probe touches the target plane or not is judged without observation by human eyes, and the pose of the manipulator corresponding to the contact is recorded after the judgment of the contact.
Step 012: and respectively calculating the pose conversion relation between the manipulator coordinate system and the flange coordinate system corresponding to each target pose according to the target pose corresponding to each contact.
Specifically, with continued reference to fig. 1, a flange coordinate system of the flange of the manipulator and a base coordinate system of the manipulator are established. The flange coordinate system describes the position and attitude of the actuator (e.g., clamp, tool, etc.) relative to the robot. When the manipulator is controlled to move so that a contact probe of a contact detection device arranged on a flange of the manipulator touches each contact point on a target plane, an actuator of the manipulator changes in gesture in the movement and operation process of contacting different contact points, and therefore the coordinates and the gestures of each base coordinate system corresponding to the contact points are different.
It will be appreciated that since the flange coordinate system describes the position and attitude of the actuator relative to the robot, there is a correspondence between the flange coordinate system and the (base) coordinate system of the manipulator. Different contact points correspond to different positioning postures, and according to the positioning postures corresponding to the contact points, the position posture conversion relation between the manipulator coordinate system and the flange coordinate system corresponding to the positioning postures is calculated. For example, the target pose corresponding to the 3 contacts is obtained, and the pose conversion relation between the manipulator coordinate system and the flange coordinate system corresponding to the 3 target poses is calculated through a pose resolving algorithm, such as a Least square method (Least square), singular Value Decomposition (SVD), and the like.
Optionally, there are at least 3 contacts in each contact that are not collinear.
Specifically, in order to improve the accuracy of the pose conversion relationship between the manipulator coordinate system and the flange coordinate system corresponding to each target pose, at least 3 non-collinear contacts exist in each contact.
Step 013: and calculating the coordinate of the calibration position according to the pose conversion relation corresponding to each calibration pose and the coplanarity relation of each contact.
Specifically, each contact is located on the same target plane (such as a calibration plate), the contacts have a coplanar relationship, and the calibration position coordinates are calculated according to the pose conversion relationship corresponding to each calibration pose and the coplanar relationship of each contact.
In this way, when the contact probe of the contact detection device contacts each contact of the target plane, the calibration pose of the manipulator is obtained, then the pose conversion relation between the manipulator coordinate system corresponding to each calibration pose and the flange coordinate system is calculated according to the calibration pose corresponding to each contact, and finally the calibration position coordinates are calculated according to the pose conversion relation corresponding to each calibration pose and the coplanarity relation of each contact. The contact probe of the contact detection device is used for touching each contact, wherein the detection contact device gives a prompt when contacting a target plane, and then the calibration pose of each contact is obtained, so that the accuracy of the obtained calibration pose of the manipulator is improved, and the accuracy of a calibration result is improved; the position and the coordinate of the calibration position are calculated according to the position and the coordinate conversion relation of the manipulator corresponding to each calibration position and the position and coordinate conversion relation of the flange corresponding to each calibration position and the coplanarity relation of each contact, so that a more accurate calibration result is obtained, and the calibration precision is further improved.
Compared with the existing method for observing through manual operation and human eyes, the method avoids the problems that accurate touch is difficult to realize under the conditions of human eye observation and manual control when the contact probe contacts the target plane, does not need to spend a great deal of time determining whether the needle point is aligned with the contact point, and improves the calibration efficiency.
Referring to fig. 3, in some embodiments, the target pose includes a position coordinate and a pose angle, and the pose conversion relationship includes a translation matrix and a rotation matrix, step 012: according to the target pose corresponding to each contact, respectively calculating pose conversion relations corresponding to each target pose, including:
step 0121: according to the position coordinates of the calibration gesture, calculating a translation matrix corresponding to the calibration gesture;
step 0122: and calculating a rotation matrix corresponding to the calibration gesture according to the gesture angle of the calibration gesture.
Specifically, after the manipulator coordinate system is established and the flange of the manipulator is established, translation is performed along the straight line directions of the X axis, the Y axis and the Z axis of the coordinate system to represent the position in space, and rotation is performed around the X axis, the Y axis and the Z axis of the coordinate system by a certain angle to represent the gesture in space. Then, the translation matrix corresponding to the calibration gesture can be calculated through the position coordinates of the calibration gesture, and the rotation matrix corresponding to the calibration gesture is calculated according to the gesture angle of the calibration gesture.
It will be appreciated that each contact has a respective corresponding translation matrix and rotation matrix. This is because it can be considered that the translation transformation, the rotation transformation, or both the translation transformation and the rotation transformation are performed with respect to the origin of the coordinate system of the manipulator. For example, assuming that the contact probe contacts contact a and contact B on the target plane, which are not at the same point, since contact a and contact B have different positions and orientations, their relative relationship (position in space, attitude, etc.) to the (base) coordinate system of the manipulator is also different, and thus each contact has its own corresponding translation matrix and rotation matrix.
Referring to fig. 4, in certain embodiments, step 013: calculating calibration position coordinates according to pose conversion relations corresponding to all the calibration poses and coplanarity relations of all the contacts, wherein the calculation comprises the following steps:
step 0131: establishing a first functional relation between a calibration position coordinate and a contact point coordinate of each contact point under a manipulator coordinate system according to the pose conversion relation corresponding to each calibration pose;
step 0132: establishing a second functional relationship between a normal vector of the target plane and contact coordinates of any three non-collinear contacts;
step 0133: based on the coplanarity of each contact, a third function relationship of a normal vector and a contact vector formed by any two contact coordinates is established;
step 0134: and calculating calibration position coordinates based on the first functional relation, the second functional relation and the third functional relation.
Specifically, according to a translation matrix and a rotation matrix respectively corresponding to the standard pose of each contact, a first functional relation between the standard position coordinates and the contact coordinates of each contact under a manipulator coordinate system is established:
wherein P is Base Is the coordinates of the contact point in the manipulator coordinate system,for a rotation matrix from the flange coordinate system to the manipulator coordinate system, < >>For a translation matrix from the flange coordinate system to the manipulator coordinate system, +.>Is the coordinates of the contact point in the flange coordinate system.
Assuming the target plane acquires six non-collinear contacts, contact A, contact B, contact C, contact D, contact E, and contact F, e.g. in order toRepresenting the rotation matrix from the flange coordinate system to the manipulator coordinate system corresponding to contact A, +.>Representing a translation matrix from a flange coordinate system to a manipulator coordinate system corresponding to the contact A, and the contacts B, C, D, E and F and so on are as follows:
by determining any three non-collinear contacts on the target plane, e.g. contact A, contact B and contact C, toRepresenting the line segment vector after connection between the contact A and the contact B, and representing the normal vector of the target plane by n, then establishing a second functional relation between the normal vector n of the target plane and the contact coordinates of any three non-collinear contacts:
n＝V AB ×V AC
because each contact is obtained after touching the target plane, a coplanar relationship exists between each contact, the normal vector is perpendicular to a line segment vector formed by any two points on the plane, and the vector is multiplied by 0. Thus, based on the coplanarity of the individual contacts, a third functional relationship of the normal vector and the contact vector formed by any two contact coordinates (assuming contact A and contact B) is established:
n·V AB ＝0
alternatively, the number of contacts is 6, and 3 contacts of the calculation vector are different from the contacts forming the contact vector.
Specifically, in order to further improve the accuracy of calibration, the number of contacts is 6, and 3 contacts of the calculation algorithm vector and the contacts forming the contact vector are different. Assuming that 6 contacts are a contact a, a contact B, a contact C, a contact D, a contact E and a contact F, and assuming that a second functional relationship is established through the contact a, the contact B and the contact C and a third functional relationship is formed through the contact D, the contact E and the contact F, the third functional relationship is:
and finally, calculating the calibration position coordinates based on the first functional relation, the second functional relation and the third functional relation.
Referring to FIG. 5, in certain embodiments, step 0134: calculating calibration location coordinates based on the first functional relationship, the second functional relationship, and the third functional relationship, comprising:
step 01341: according to the physical size of the actuator, determining initial position coordinates of a center point of the actuator when the center point of the actuator is mounted on the flange;
step 01342: and calculating the calibration position coordinate based on a preset nonlinear solving algorithm, an initial position coordinate, a first functional relation, a second functional relation and a third functional relation.
The preset nonlinear solving algorithm may be a gaussian newton iterative method, a Levenberg-Marquarelt (LM) method, or the like.
Specifically, through the physical size of an actuator of the manipulator, initial position coordinates of a center point of the actuator when the actuator is mounted on the flange are determined, iteration is performed based on a preset nonlinear solving algorithm, a first functional relation, a second functional relation and a third functional relation by taking the initial position coordinates as initial values, and calibration position coordinates are calculated.
Referring to fig. 6 and 7, in some embodiments, the calibration method further includes:
step 014: calculating the predicted coordinates of each contact under the manipulator coordinate system according to the pose conversion relation corresponding to each target pose and the calibrated position coordinates obtained through calibration;
step 015: calculating root mean square error of the distance between the predicted coordinates corresponding to each contact point and the target plane;
step 016: under the condition that the root mean square error is smaller than the preset error, determining that calibration of the coordinate of the calibration position is completed;
step 017: and under the condition that the root mean square error is larger than the preset error, taking the calibrated position coordinate obtained by calibration as an initial position coordinate, and re-entering a step of calculating the calibrated position coordinate based on a preset nonlinear solving algorithm, the initial position coordinate, the first functional relation, the second functional relation and the third functional relation.
The preset error can be set according to specific application scenes, required precision and the like, when the root mean square error is smaller than the preset error, the accuracy of calibration is higher, the expected precision level is reached, and the difference is within an acceptable range.
Specifically, after the calibration position coordinates are calculated, the calibration position coordinates are verified. And calculating the predicted coordinates of each contact under the manipulator coordinate system based on the pose conversion relation corresponding to the calibration pose of each contact and the calibrated calibration position coordinates, and then calculating the root mean square error of the distance between the predicted coordinates corresponding to each contact and the target plane.
It can be understood that, since all the contacts are coplanar, the calibration of the calibration position coordinates is determined to be completed when the root mean square error is smaller than the preset error; and under the condition that the root mean square error is larger than the preset error, taking the calibrated calibration position coordinate as an initial position coordinate in order to obtain accurate calibration, and re-entering the steps of calculating the calibration position coordinate based on a preset nonlinear solving algorithm, the initial position coordinate, the first functional relation, the second functional relation and the third functional relation, and restarting iteration.
Referring to fig. 8, in order to better implement the calibration method according to the embodiment of the present application, the embodiment of the present application further provides a calibration device 10 for calibrating a calibration position coordinate of a center point of an actuator installed on a manipulator under a flange coordinate system of the manipulator. The calibration device 10 may include an acquisition module 11, a first calculation module 12 and a second calculation module 13, where the acquisition module 11 is configured to acquire a calibration pose of the manipulator when a contact probe of the contact detection device contacts each contact point of the target plane (calibration board), the contact detection device is disposed on a flange, a position of the contact probe coincides with a center point of the actuator, and the contact detection device is configured to send a prompt message when the contact probe contacts the target plane; the first calculating module 12 is configured to calculate, according to the target poses corresponding to the contacts, pose conversion relationships between the manipulator coordinate system and the flange coordinate system corresponding to the target poses; the second calculating module 13 is configured to calculate the calibration position coordinates according to the pose conversion relationship corresponding to each calibration pose and the coplanarity relationship of each contact.
In one embodiment, the calibration pose includes a position coordinate and a pose angle, the pose conversion relationship includes a translation matrix and a rotation matrix, and the first calculation module 12 is specifically further configured to calculate the translation matrix corresponding to the calibration pose according to the position coordinate of the calibration pose, and calculate the rotation matrix corresponding to the calibration pose according to the pose angle of the calibration pose.
In one embodiment, the second computing module 13 is specifically further configured to establish a first functional relationship between the calibration position coordinate and the contact point coordinate of each contact point under the manipulator coordinate system according to the pose conversion relationship corresponding to each calibration pose; establishing a second functional relationship between a normal vector of the target plane and contact coordinates of any three non-collinear contacts; based on the coplanarity of each contact, a third function relationship of a normal vector and a contact vector formed by any two contact coordinates is established; and calculating calibration position coordinates based on the first functional relation, the second functional relation and the third functional relation.
In one embodiment, the second calculation module is specifically further configured to determine an initial position coordinate of the center point of the actuator when the center point of the actuator is mounted on the flange according to the physical size of the actuator, and calculate the calibration position coordinate based on a preset nonlinear solution algorithm, the initial position coordinate, the first functional relationship, the second functional relationship, and the third functional relationship.
In one embodiment, the calibration device further includes a third calculation module 14, where the third calculation module 14 is configured to calculate, according to the pose conversion relationship corresponding to each calibration pose and the calibrated calibration position coordinates, a predicted coordinate of each contact under the manipulator coordinate system; calculating root mean square error of the distance between the predicted coordinates corresponding to each contact point and the target plane; under the condition that the root mean square error is smaller than the preset error, determining that calibration of the coordinate of the calibration position is completed; and under the condition that the root mean square error is larger than the preset error, taking the calibrated position coordinate obtained by calibration as an initial position coordinate, and re-entering a step of calculating the calibrated position coordinate based on a preset nonlinear solving algorithm, the initial position coordinate, the first functional relation, the second functional relation and the third functional relation.
The calibration device 10 is described above in connection with the accompanying drawings from the perspective of functional modules, which may be implemented in hardware, instructions in software, or a combination of hardware and software modules. Specifically, each step of the method embodiments in the embodiments of the present application may be implemented by an integrated logic circuit of hardware in a processor and/or an instruction in software form, and the steps of the method disclosed in connection with the embodiments of the present application may be directly implemented as a hardware encoding processor or implemented by a combination of hardware and software modules in the encoding processor. Alternatively, the software modules may be located in a well-established storage medium in the art such as random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, and the like. The storage medium is located in a memory, and the processor reads information in the memory, and in combination with hardware, performs the steps in the above method embodiments.
Referring again to fig. 1, the calibration system 1000 of the embodiment of the present application includes calibration position coordinates for calibrating a center point of an actuator mounted on the manipulator 400 in a flange coordinate system of the manipulator 400, and the calibration system 1000 includes: a calibration device 100 comprising a target plane 100; the contact detection device 200 is arranged on the flange, the position of the contact probe 202 coincides with the center point of the actuator, and the contact detection device 200 is used for sending out prompt information when the contact probe 202 contacts the target plane 100; and the processor is used for executing the calibration method of any embodiment.
Referring again to fig. 9, the computer device of the present embodiment includes a processor 302, a memory 303, and a computer program, where the computer program is stored in the memory 303 and executed by the processor 302, and the computer program includes instructions for executing the calibration method of any of the above embodiments.
It will be appreciated by those skilled in the art that the structure shown in fig. 9 is merely a block diagram of a portion of the structure associated with the present application and is not limiting of the computer device to which the present application applies, and that a particular computer device may include more or fewer components than shown, or may combine some of the components, or have a different arrangement of components.
Referring to fig. 10, the embodiment of the present application further provides a computer readable storage medium 600, on which a computer program 610 is stored, where the computer program 610, when executed by the processor 620, implements the steps of the calibration method of any of the foregoing embodiments, which is not described herein for brevity.
In the description of the present specification, reference to the terms "certain embodiments," "in one example," "illustratively," and the like, means that a particular feature, structure, material, or characteristic described in connection with the embodiments or examples is included in at least one embodiment or example of the present application. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.
Any process or method descriptions in flow charts or otherwise described herein may be understood as representing modules, segments, or portions of code which include one or more executable instructions for implementing specific logical functions or steps of the process, and further implementations are included within the scope of the preferred embodiment of the present application in which functions may be executed out of order from that shown or discussed, including substantially concurrently or in reverse order, depending on the functionality involved, as would be understood by those reasonably skilled in the art of the embodiments of the present application.
While embodiments of the present application have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the present application, and that variations, modifications, alternatives, and variations may be made to the above embodiments by one of ordinary skill in the art within the scope of the present application.
Claims (10)
1. A calibration method for calibrating a calibration position coordinate of a center point of an actuator mounted on a manipulator in a flange coordinate system of the manipulator, the method comprising:
when a contact probe of a contact detection device contacts each contact of a target plane, the target position pose of the manipulator is acquired, the contact detection device is arranged on the flange, the position of the contact probe coincides with the center point of the actuator, and the contact detection device is used for sending prompt information when the contact probe contacts the target plane;
according to the positioning pose corresponding to each contact, respectively calculating pose conversion relations between a manipulator coordinate system and a flange coordinate system corresponding to each positioning pose;
and calculating the calibration position coordinates according to the pose conversion relation corresponding to each calibration pose and the coplanarity relation of each contact.
2. The calibration method according to claim 1, wherein the calibration positions include position coordinates and attitude angles, the position-to-attitude conversion relation includes a translation matrix and a rotation matrix, and the calculating the position-to-attitude conversion relation corresponding to each of the calibration positions according to the calibration positions corresponding to each of the contacts includes:
calculating a translation matrix corresponding to the calibration gesture according to the position coordinates of the calibration gesture;
and calculating a rotation matrix corresponding to the calibration gesture according to the gesture angle of the calibration gesture.
3. The calibration method according to claim 1, wherein the calculating the calibration position coordinates according to the pose conversion relationship corresponding to each of the calibration poses and the coplanarity relationship of each of the contacts includes:
establishing a first functional relation between the calibration position coordinates and the contact coordinates of each contact under a manipulator coordinate system according to the pose conversion relation corresponding to each calibration pose;
establishing a second functional relationship between a normal vector of the target plane and the contact coordinates of any three non-collinear contacts;
establishing a third functional relation of the normal vector and a contact vector formed by any two contact coordinates based on the coplanarity relation of all the contacts;
and calculating the calibration position coordinates based on the first functional relation, the second functional relation and the third functional relation.
4. A calibration method according to claim 3, wherein the number of contacts is 6, and the 3 contacts for calculating the normal vector are different from the contacts forming the contact vector.
5. A calibration method according to claim 3, wherein the calculating the calibration position coordinates based on the first functional relation, the second functional relation and the third functional relation comprises:
according to the physical size of the actuator, determining initial position coordinates of a center point of the actuator when the center point of the actuator is mounted on the flange;
and calculating the calibration position coordinate based on a preset nonlinear solving algorithm, the initial position coordinate, the first functional relation, the second functional relation and the third functional relation.
6. The method of calibrating according to claim 5, further comprising:
calculating the predicted coordinates of each contact under a manipulator coordinate system according to the pose conversion relation corresponding to each target pose and the calibrated position coordinates;
calculating root mean square error of the distance between the predicted coordinates corresponding to each contact point and the target plane;
under the condition that the root mean square error is smaller than a preset error, determining that the calibration of the calibration position coordinates is completed;
and under the condition that the root mean square error is larger than a preset error, taking the calibrated position coordinate as the initial position coordinate, and re-entering a step of calculating the calibrated position coordinate based on a preset nonlinear solving algorithm, the initial position coordinate, the first functional relation, the second functional relation and the third functional relation.
7. Calibration method according to claim 1, characterized in that there are at least 3 contacts of each contact that are not collinear.
8. The method of calibrating according to claim 1, wherein the contact detection device comprises a sphere bar instrument comprising a mounting portion, a probe and the contact probe, the probe being arranged at the mounting portion, the contact probe being arranged at an end of the probe remote from the mounting portion.
9. A calibration device for calibrating a calibration position coordinate of a center point of an actuator mounted on a manipulator in a flange coordinate system of the manipulator, the device comprising:
the acquisition module is used for acquiring the target position pose of the manipulator when a contact probe of the contact detection device contacts each contact of a target plane (a calibration plate), the contact detection device is arranged on the flange, the position of the contact probe coincides with the center point of the actuator, and the contact detection device is used for sending prompt information when the contact probe contacts the target plane;
the first calculation module is used for calculating pose conversion relations between a manipulator coordinate system and a flange coordinate system corresponding to each target pose according to the target poses corresponding to each contact;
and the second calculation module is used for calculating the calibration position coordinates according to the pose conversion relation corresponding to each calibration pose and the coplanarity relation of each contact.
10. A calibration system for calibrating calibration position coordinates of a center point of an actuator mounted on a manipulator in a flange coordinate system of the manipulator, the calibration system comprising:
a calibration device comprising a target plane;
the contact detection device is arranged on the flange, the position of the contact probe is coincident with the center point of the actuator, and the contact detection device is used for sending out prompt information when the contact probe contacts the target plane;
a processor for performing the calibration method of any one of claims 1-8.
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