CN117140535B - Robot kinematics parameter calibration method and system based on single measurement - Google Patents
Robot kinematics parameter calibration method and system based on single measurement Download PDFInfo
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
- B25J9/00—Programme-controlled manipulators
- B25J9/16—Programme controls
- B25J9/1679—Programme controls characterised by the tasks executed
- B25J9/1692—Calibration of manipulator
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
- B25J19/00—Accessories fitted to manipulators, e.g. for monitoring, for viewing; Safety devices combined with or specially adapted for use in connection with manipulators
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Abstract
The scheme discloses a robot kinematics parameter calibration method and system based on single measurement, wherein the method comprises the following steps: s1, respectively installing a robot and a calibration block to respective corresponding positions on a bottom plate; s2, calibrating zero positions of displacement sensors at the end effector; s3, driving the tail end of the robot to move, and performing point location measurement on the surface of the calibration block by using a six-point positioning method to obtain a nominal pose; s4, replacing the positions of the calibration blocks on the bottom plate, and repeating the step S3 to obtain at least two groups of nominal poses; s5, comparing the nominal pose of the calibration block with the actual pose obtained based on the known relative position to correct the robot kinematics nominal parameters. By providing a simple calibration system and a calibration method realized based on the calibration system, the robot kinematics parameter calibration can be completed by using a low-cost displacement sensor and a related simple jig without using expensive external measurement equipment.
Description
Technical Field
The invention belongs to the technical field of robots, and particularly relates to a robot kinematics parameter calibration method and system based on single measurement.
Background
With the continuous improvement of the technical level of industrial robots, industrial robots have begun to enter the high-precision manufacturing fields of aerospace manufacturing, precision machining, biomedical and the like.
The industrial robot production process is strictly carried out according to the drawing, but errors such as screws and angles of transmission shafts exist in the assembly process, and in order to improve the precision, the assembly process needs to be calibrated before first use.
Over the last two decades, tremendous advances have been made in external measurement devices and methods for industrial robot arm calibration, due to the ever-increasing demands on robots in the field of industrial manufacturing. Most manufacturers wish to use offline programming software to plan the robot tip movement to achieve a high efficiency, high accuracy robot tip machining trajectory path instead of a manual teaching mode.
However, since the theoretical parameters of the industrial robot are inconsistent with the actual parameters, the accuracy of the actual robot end motion cannot be ensured in the off-line programming software. Therefore, the robot needs to be calibrated with parameters to obtain the actual parameters of the robot. However, most calibration methods involve expensive external measurement equipment, such as laser trackers and the like.
How to realize a low-cost, high-precision, automatic and easy-to-operate machine ginseng number calibration scheme by designing a novel calibration device and method is an urgent problem to be solved.
Disclosure of Invention
The invention aims to solve the problems and provides a robot kinematics parameter calibration method and system based on single measurement.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
a robot kinematics parameter calibration method based on single measurement comprises the following steps:
s1, respectively mounting a robot and a calibration block to respective corresponding positions on a bottom plate to ensure that the calibration block and the robot have known relative positions;
s2, calibrating a zero position of a displacement sensor at the end effector, and determining the position length of the measuring end part from the tail end of the robot when the zero position of the displacement sensor is read;
s3, driving the tail end of the robot to move, performing point location measurement on the surface of the calibration block by using a six-point positioning method, recording joint angle and sensor displacement data, and calculating to obtain the nominal pose of the coordinate system of the calibration block relative to the coordinate system of the machine base;
s4, after at least one group of position points of the calibration block are measured on the bottom plate, replacing the position of the calibration block on the bottom plate and repeating the step S3, so that the nominal pose of at least two groups of calibration block coordinate systems relative to the machine base coordinate system is obtained;
s5, comparing the nominal pose of the calibration block with the actual pose obtained based on the known relative position to correct the robot kinematics nominal parameters. The relative position relationship on the bottom plate ensures that the two have a definite corresponding relationship, so that the actual pose can be obtained according to the mechanical structure of the bottom plate.
In the above method for calibrating the kinematic parameters of the robot based on single measurement, step S5 specifically includes:
and comparing the calculated nominal pose of the calibration block with the actual pose based on the mechanical structure of the bottom plate, establishing a corresponding objective function, and searching a group of approximate solutions to minimize errors between the nominal pose and the actual pose, thereby correcting the nominal parameters of the robot kinematics.
In the robot kinematics parameter calibration method based on single measurement, the objective function is as follows:
k represents the number of data sets, each set of data is obtained by measuring the position points through a six-point positioning method at a time, and at least one set of data is obtained by replacing the position of the calibration block on the bottom plate at each time;
actual pose of calibration block coordinate system relative to machine base coordinate systemThe mathematical model established in combination with both the actual displacement of the displacement sensor is +.>，/>The function represents the robot positive kinematics, i.e. +.>Q represents the corresponding corner of six joints of the robot +.>，P n Representing nominal D-H parameters,>representing the D-H parameter error of the robot,representing the actual pose of the measuring tip with respect to the robot tip, wherein the right subscript E is the displacement sensor variation representing a set of measurement data +.>Representative is the displacement variation recorded corresponding to a group of 3-2-1 six-point measurement modes.
In the above method for calibrating the kinematic parameters of the robot based on single measurement, step S3 specifically includes:
s31, establishing a machine base coordinate system, an end coordinate system, a calibration block coordinate system and a displacement sensor measuring end coordinate system on a robot end effector;
s32, after zero calibration of the displacement sensor is completed, driving the tail end of the robot to move so that the displacement sensor at the tail end of the robot can measure the position points on the surface of the calibration block, and recording corresponding joint angles and sensor displacement data;
s33, measuring the sensor displacement obtained on the surface of the calibration block, carrying out mathematical solution on the coordinate system of the calibration block by combining a six-point positioning method, and calculating to obtain the nominal pose of the coordinate system of the calibration block relative to the coordinate system of the robot base.
In the above-mentioned robot kinematic parameter calibration method based on single measurement, in step S33, the six-point positioning method performs mathematical solution on the calibration block coordinate system specifically including:
determining a plane equation of each plane of the calibration block based on the coordinate system of the calibration block, and randomly selecting a position point vector on the plane of the sensor measurement calibration block;
converting the plane position point vector and the normal vector into a coordinate system of the machine base, and determining a plane equation of the plane in the coordinate system of the machine base according to the position point vector and the normal vector in the coordinate system of the machine base;
calculating according to the serial characteristics of the robot to obtain the position of a sensor measuring end part coordinate system relative to a machine base coordinate system, substituting the measured end part position coordinate into a calibration block plane equation under the machine base coordinate system to obtain a mathematical relation between the displacement of the robot end displacement sensor and the relative pose of the calibration block coordinate system relative to the machine base coordinate system;
and establishing a pose model of the calibration block coordinate system relative to the machine base coordinate system according to the mathematical relation, and solving the pose model by adopting a nonlinear iterative least square algorithm to obtain the nominal pose of the calibration block coordinate system relative to the machine base coordinate system of the robot.
In the above method for calibrating the kinematic parameters of the robot based on single measurement, the base plate is provided with a plurality of mounting shafts, and in step S4, the positions of the calibration blocks on the base plate are replaced by mounting the calibration blocks to different mounting shafts. Each axis can correspond to n groups of data, each group of data comprises data obtained by 3-2-1 measurement mode of the tail end of the robot on three surfaces of the calibration block, and n can be 1 or other natural values.
The number of the mounting shafts is set by a person skilled in the art according to the need, and is generally set according to the robot work area, for example, three mounting shafts of the UR10 robot corresponding to the present solution just cover the work area.
In the above method for calibrating the kinematic parameters of the robot based on single measurement, step S2 specifically includes:
adjusting the angle of the robot joint to a state that the tail end is horizontal;
and installing the zero calibration device on the end effector, and matching a flat key on the zero calibration device with a groove on the end effector so as to enable a baffle on the zero calibration device to prop against the measuring end part of the displacement sensor, thereby performing reading zeroing treatment.
The robot kinematics parameter calibration system based on single measurement comprises a robot to be calibrated and a main control connected with the robot, and also comprises a calibration block, a displacement sensor and a bottom plate, wherein the bottom plate is provided with a robot installation position and an installation shaft, and the robot is installed at the robot installation position, and the calibration block is installed at the installation shaft so that a known relative position relationship exists between the robot and the calibration block;
the displacement sensor is arranged at the tail end of the robot to be calibrated through an end effector and is connected with the main control;
in the calibration process, the master control obtains the point position of the surface of the calibration block through the displacement sensor so as to determine the nominal pose of the coordinate system of the calibration block relative to the coordinate system of the machine base, determines the actual pose of the coordinate system of the calibration block relative to the coordinate system of the machine base based on the known relative position relation, and performs calibration correction on the kinematic parameters of the robot through the error of the comparison between the nominal pose and the actual pose.
The end effector is arranged on a corresponding hole site at the tail end of the robot through an inner hexagon screw and a locating pin; the displacement sensor is fixed on the corresponding hole site of the end effector through a nut, so that the superposition of the z-axis direction of the tail end of the robot and the measuring axis direction of the displacement sensor is ensured.
In the robot kinematics parameter calibration system based on single measurement, the bottom plate is fixed on the working platform;
the robot is arranged on the bottom plate through the socket head cap screws and the positioning pins;
the base plate is provided with at least one mounting shaft, and the calibration block is provided with a mounting hole site corresponding to the mounting shaft;
the master control obtains the relative position of the calibration block and the robot according to the mechanical structure of the bottom plate. The main mode is that the base plate is manufactured according to a machining drawing and comprises an installation shaft and an installation position on the base plate, and the main control can acquire the position information of the installation position of the robot on the base plate and the position information of the installation shaft according to the mechanical structure of the base plate so as to determine the relative position relation between the robot and the calibration block and acquire the actual pose of the coordinate system of the calibration block relative to the coordinate system of the base of the robot.
In the robot kinematics parameter calibration system based on single measurement, the bottom plate is provided with three mounting shafts;
the three mounting shafts are uniformly distributed on the bottom plate, and the calibration block is matched with any one of the mounting shafts on the bottom plate.
The zero calibration device is used for calibrating the zero of the sensor;
the zero calibration device is arranged on the end effector in a key slot matching mode and props against the end part of the displacement sensor, zero calibration is carried out on the displacement sensor on the end effector, the position length of the end part, which is far away from the tail end of the robot, is measured when zero reading is obtained, the position length is a certain quantity which is known by a mechanical structure, and the key point is that the sensor reading of the displacement sensor returns to zero in a zero calibration state so as to facilitate subsequent measurement and calculation.
When the displacement sensor performs measurement, the generated displacement and the position length during zero calibration are calculated to obtain the actual position length of the measuring end part from the tail end of the robot in the measurement state.
The invention has the advantages that: the scheme provides a simple calibration system and a calibration method realized based on the calibration system, does not need to use expensive external measurement equipment, and can finish the calibration of the kinematic parameters of the robot by only using a low-cost displacement sensor and a related simple jig. The method realizes the purposes of low cost, high precision, automation and easy operation in the process of calibrating the ginseng number of the machine, and has wide application fields and application prospects.
Drawings
FIG. 1 is an overall flow chart of a robot kinematics parameter calibration method based on single measurement provided by an embodiment of the invention;
FIG. 2 is a diagram of a specific implementation device of a method and a system for calibrating kinematic parameters of a robot based on single measurement according to an embodiment of the present invention;
FIG. 3 is a schematic view of a robot joint configuration in a sensor zero calibration state provided by an embodiment of the present invention;
FIG. 4 is a diagram of an implementation device of a zero calibration method of a robot end sensor according to an embodiment of the present invention;
FIG. 5 is a block diagram of a zero calibration device for a robot end sensor according to an embodiment of the present invention;
FIG. 6 is a schematic diagram of a mathematical relationship between a robot kinematic parameter model and a single measurement model according to an embodiment of the present invention;
FIG. 7 is a schematic diagram of a closed-loop relationship between an actual pose and a nominal pose of a calibration block relative to a base provided by an embodiment of the present invention.
Reference numerals illustrate: the device comprises a 1-robot, a 2-end effector, a 3-displacement sensor, a 4-calibration block, a 5-bottom plate, a 6-working platform and a 7-zero calibration device;is the machine base coordinate system of the robot, +.>Is the end coordinate system of the robot, +.>For calibrating the block coordinate system, < >>An end coordinate system is measured for the displacement sensor.
Detailed Description
The invention will be described in further detail with reference to the drawings and the detailed description.
As shown in fig. 1, this embodiment provides a method for calibrating a kinematic parameter of a robot based on a single measurement, where the method uses a tool having a base plate made according to a mechanical drawing, a calibration block capable of being mounted at a corresponding position on the base plate, and a displacement sensor mounted at an end effector, the end effector being mounted at a robot end, the base plate having a specific robot mounting position and a mounting shaft for mounting the calibration block, so that the relative position of the robot and the calibration block can be known, and the method for calibrating the kinematic parameter of the robot based on the tool includes:
step S1: as shown in fig. 2, the base plate 5 is fixed to the work platform 6, and the robot 1 is mounted on the corresponding hole site of the base plate 5 by socket head cap screws and positioning pins. The robot is connected with the master control, and the master control mainly comprises a robot control box and a computer system. The end effector 2 is arranged on a corresponding hole site at the tail end of the robot through an inner hexagon screw and a locating pin, and the displacement sensor 3 is fixed on the hole site of the end effector 2, so that the coincidence of the measuring axis direction of the displacement sensor 3 and the z-axis direction of the tail end of the robot is ensured.
Three uniformly distributed mounting shafts are arranged on the bottom plate 5, and each mounting shaft is provided with a flat key matched with the mounting hole of the calibration block 4. The calibration block 4 is fixed on any mounting shaft position on the bottom plate 5, and the mounting holes on the calibration block 4 are matched with the flat keys of the mounting shafts, so that the position of the calibration block 4 is accurate and known relative to the robot 1, and is consistent with the size and the position of a mechanical drawing.
The measurement between the displacement sensor 3 and the calibration block 4 may be a contact type digital displacement sensor or a laser displacement sensor, and the contact or non-contact type is not particularly limited herein, and the contact type is taken as an example in this embodiment, and the non-contact type is similar and is not described herein. The displacement sensor 3 can reach 0.01mm or higher precision according to different models, the displacement sensor 3 can be connected with a computer, and the computer can acquire the measurement data of the displacement sensor 3 in real time, analyze the data and record the data.
Step S2: the displacement sensor is calibrated before measuring by using a zero calibration device 7 to obtain a known fixed value of the position length of the measuring end part of the displacement sensor from the tail end of the robotWhen the displacement sensor reading is zeroed, the known constant value +.>It can be known from the mechanical drawing of the zero calibration device 7, so that the displacement produced during the measurement is dependent on the displacement sensor>The actual distance of the measuring tip from the robot tip can be calculated>。
At zero calibration of the displacement sensor, the robot joint angle is modulated to a state that the tail end is horizontal, as shown in fig. 3. When the robot end is in a horizontal state, the zero calibration device 7 can be matched with the end effector 2 by means of self gravity, as shown in fig. 4. The zero calibration device is provided with 2 flat keys, as shown in fig. 5, and the positions of the flat keys are just matched with the grooves on the end effector, so that the baffle plate on the zero calibration device 7 can be ensured to prop against the measuring end part of the displacement sensor, and the reading zeroing operation is performed.
Step S3: first, a coordinate system is established for a robot calibration system, as shown in FIG. 7, a robot base coordinate system is establishedRobot end coordinate System->Coordinate system of calibration block->Displacement on robotic end effectorSensor measurement end coordinate System +.>. Wherein the machine base coordinate system is the center position of the robot machine base; the robot tail end coordinate system is the center position of the robot tail end; the coordinate system of the calibration block is the center position of the calibration block; the measuring end coordinate system is the measuring top end of the displacement sensor.
Ensuring that the conversion relationship between the respective coordinate systems is correct, as shown in fig. 7, includes:
the initial data of the robot coordinate system is obtained by nominal values, namely the robot tail end coordinate systemRelative to the robot base coordinate system>Nominal pose of +.>The method comprises the steps of carrying out a first treatment on the surface of the Wherein q represents the corresponding corner of six joints of the robot +.>；/>The function represents the positive kinematics of the robot, namelyThe method comprises the steps of carrying out a first treatment on the surface of the Since the exact actual D-H parameters cannot be obtained during the production of the robot, the nominal D-H parameters of the robot can only be obtained by looking up the relevant robot using the manual +.>。
Measuring end coordinate system of displacement sensorRelative to the robot end coordinate systemIs>Namely, the displacement is calculated by the mechanical drawing size and the displacement measured by a displacement sensor:
（1）；
measuring end coordinate system of displacement sensorRelative to the robot base coordinate systemNominal pose->The method comprises the following steps:
（2）；
calibration block coordinate systemRelative to the robot base coordinate system>The nominal pose relationship of (2) can be obtained by performing point location measurement calculation on the surface of the calibration block by using a six-point positioning principle, as shown in fig. 6.
A robot kinematics parameter calibration model based on a displacement sensor is provided, wherein the model combines a robot kinematics meaning parameter error with a displacement measured by the displacement sensor and establishes a corresponding mathematical expression. The positioning error of the robot is converted into the displacement error of the displacement sensor, so that the calibration system becomes more practical and convenient.
Knowing the mechanical drawing size of the base plate, a calibration block coordinate system can be obtainedRelative to the robot base coordinate system>Is>The method comprises the following steps:
（3）；
as shown in fig. 6, the robot is driven to move so that the displacement sensor performs point location measurement on three intersecting planes of the calibration block in a 3-2-1 six-point positioning manner. Integrating the six displacement amounts into a displacement amount vectorTo->Sensor measurements of displacement are mathematically modeled for an example:
wherein,is the position vector of the measuring end coordinates of the displacement sensor relative to the coordinate system of the machine base, i.e. +.>The position column vector of the coordinate matrix is +.>；/>The plane equation is a plane equation of a calibration block contacted with the measuring end part of the displacement sensor, and the plane equation is based on a coordinate system of the calibration block; />Is->The coordinate of any point of the plane in which the plane equation is located is usually set as the intersection point of the plane and the extension line of the coordinate axis of the calibration block, i.e. +.>(the known calibration block is a cube with 200mm sides); />Is->Normal vector of plane equation and based on calibration block coordinate system, then +.>(the normal vector should be kept in the same positive direction as the displacement sensor).
Will now bePosition vector sum->The direction vectors are converted into two vectors under the coordinate system of the machine base in a coordinate conversion mode:
（4）；
（5）；
will beConversion of the plane equation into the plane equation in the coordinate system of the machine base>：
（6）；
（7）；
Measuring the coordinate value of the end part by a displacement sensorSubstituting formula (7) yields the expression:
（8）；
the same modeling method is used for obtaining the actual position and the pose of the coordinate system of the rest sensor measurement displacement and the calibration block relative to the coordinate system of the machine baseIs defined by the relation:
（9）；
（10）；
（11）；
（12）；
（13）；
the actual pose of the calibration block coordinate system relative to the machine base coordinate system can be obtained from the formulas (8) to (13)Nominal pose of the measuring end coordinate system relative to the base coordinate system>Is a relationship of (3).
The actual pose of the calibration block coordinate system relative to the machine base coordinate systemActual displacement amount of displacement sensorThe two are combined to build a mathematical model, and the following relation is obtained:
（14）；
wherein the method comprises the steps ofRepresenting the D-H parameter error of the robot.
Step S4: and (3) carrying out surface point position measurement by matching the calibration blocks with the rest two axial positions, recording joint angle and sensor displacement data, carrying out parameter calibration calculation on the nominal pose of a plurality of groups of calibration block coordinate systems relative to the base coordinate system and the actual pose of a corresponding plurality of groups of calibration block coordinate systems relative to the base coordinate system through experiments, so that the tail end error of the robot is compensated, the tail end local precision of the robot in a working area can be improved, and the working area range with good tail end precision of the robot is enlarged.
Step S5: in the calculation process, multiple groups of experiments are usually required, and the robot measures the calibration block under different postures by using the displacement sensor. Assume that proceedkThe group experiment collects a plurality of measurement data points for the pose of the calibration block, simultaneously records the robot joint angle corresponding to each point,kthe following relationship exists for the group experiments:
（15）；
equation (15) is a nonlinear overdetermined equation set, an objective function needs to be established to obtain an optimal solution of the equation set, and a set of approximate solutions is found to minimize an approximation error of the system, namely:
（16）；
in the method, in the process of the invention,representing a 2-norm. In the optimization process, a nonlinear least square optimization algorithm is used for carrying out numerical solution, and the robot kinematic meaning parameters are corrected, so that the end accuracy of the robot is improved.
In conclusion, the invention realizes the purposes of low cost, high precision, automation and easy operation in the process of calibrating the ginseng number of the machine, and has wide application fields and application prospects.
The specific embodiments described herein are offered by way of example only to illustrate the spirit of the invention. Those skilled in the art may make various modifications or additions to the described embodiments or substitutions thereof without departing from the spirit of the invention or exceeding the scope of the invention as defined in the accompanying claims.
Claims (9)
1. The robot kinematics parameter calibration method based on single measurement is characterized by comprising the following steps of:
s1, respectively mounting a robot and a calibration block to respective corresponding positions on a bottom plate to ensure that the calibration block and the robot have known relative positions;
s2, calibrating a zero position of a displacement sensor at the end effector, and determining the position length of the measuring end part from the tail end of the robot when the zero position of the displacement sensor is read;
s3, driving the tail end of the robot to move, performing point location measurement on the surface of the calibration block by using a six-point positioning method, recording joint angle and sensor displacement data, and calculating to obtain the nominal pose of the coordinate system of the calibration block relative to the coordinate system of the machine base;
s4, after at least one group of position points of the calibration block are measured on the bottom plate, replacing the position of the calibration block on the bottom plate and repeating the step S3, so that the nominal pose of at least two groups of calibration block coordinate systems relative to the machine base coordinate system is obtained;
s5, comparing the nominal pose of the calibration block with an actual pose obtained based on a known relative position, establishing a corresponding objective function, and searching a group of approximate solutions to minimize errors between the nominal pose and the actual pose, so as to correct the kinematic nominal parameters of the robot.
2. The robot kinematics parameter calibration method based on single measurement according to claim 1, wherein the objective function is as follows:
k represents the number of data sets, each set of data is obtained by measuring the position points through a six-point positioning method at a time, and at least one set of data is obtained by replacing the position of the calibration block on the bottom plate at each time;
actual pose of calibration block coordinate system relative to machine base coordinate systemThe mathematical model established in combination with both the actual displacement of the displacement sensor is +.>f fk The function represents the positive kinematics of the robot, namelyq represents the rotation angle q= [ q ] corresponding to six joints of the robot 1 ，q 2 ，q 3 ，q 4 ，q 5 ，q 6 ] T ，P n Representing nominal D-H parameters, ΔP representing D-H parameter error of the robot, +.>Representing the actual pose of the measuring end relative to the end of the robot, wherein the right subscript E is the displacement sensor variation e= [ E ] representing a set of measurement data 1 ，e 2 ，e 3 ，e 4 ，e 5 ，e 6 ] T Representative is the displacement variation recorded corresponding to a group of 3-2-1 six-point measurement modes.
3. The method for calibrating the kinematic parameters of the robot based on single measurement according to claim 1, wherein the step S3 specifically comprises:
s31, establishing a machine base coordinate system, an end coordinate system, a calibration block coordinate system and a displacement sensor measuring end coordinate system on a robot end effector;
s32, after zero calibration of the displacement sensor is completed, driving the tail end of the robot to move so that the displacement sensor at the tail end of the robot can measure the position points on the surface of the calibration block, and recording corresponding joint angles and sensor displacement data;
s33, measuring the sensor displacement obtained on the surface of the calibration block, carrying out mathematical solution on the coordinate system of the calibration block by combining a six-point positioning method, and calculating to obtain the nominal pose of the coordinate system of the calibration block relative to the coordinate system of the robot base.
4. The method for calibrating kinematic parameters of a robot based on single measurement according to claim 3, wherein in step S33, the mathematical solution of the calibration block coordinate system by the six-point positioning method specifically comprises:
determining a plane equation of each plane of the calibration block based on the coordinate system of the calibration block, and randomly selecting a position point vector on the plane of the sensor measurement calibration block;
converting the plane position point vector and the normal vector into a coordinate system of the machine base, and determining a plane equation of the plane in the coordinate system of the machine base according to the position point vector and the normal vector in the coordinate system of the machine base;
calculating according to the serial characteristics of the robot to obtain the position of a sensor measuring end part coordinate system relative to a machine base coordinate system, substituting the measured end part position coordinate into a calibration block plane equation under the machine base coordinate system to obtain a mathematical relation between the displacement of the robot end displacement sensor and the relative pose of the calibration block coordinate system relative to the machine base coordinate system;
and establishing a pose model of the calibration block coordinate system relative to the machine base coordinate system according to the mathematical relation, and solving the pose model by adopting a nonlinear iterative least square algorithm to obtain the nominal pose of the calibration block coordinate system relative to the machine base coordinate system of the robot.
5. A method of calibrating a kinematic parameter of a robot based on a single measurement according to claim 3, wherein the base plate has a plurality of mounting shafts, and the calibration block is replaced on the base plate by mounting the calibration block to a different mounting shaft in step S4.
6. The method for calibrating the kinematic parameters of the robot based on single measurement according to claim 3, wherein the step S2 specifically comprises:
adjusting the angle of the robot joint to a state that the tail end is horizontal;
and installing the zero calibration device on the end effector, and matching a flat key on the zero calibration device with a groove on the end effector so as to enable a baffle on the zero calibration device to prop against the measuring end part of the displacement sensor, thereby performing reading zeroing treatment.
7. The robot kinematics parameter calibration system based on single measurement comprises a robot to be calibrated and a main control connected with the robot to be calibrated, and is characterized by further comprising a calibration block, a displacement sensor and a bottom plate, wherein the bottom plate is provided with a robot installation position and an installation shaft, and the robot is installed at the robot installation position, and the calibration block is installed at the installation shaft so that a known relative position relationship exists between the robot and the calibration;
the displacement sensor is arranged at the tail end of the robot to be calibrated through an end effector and is connected with the main control;
in the calibration process, the master control obtains the point position of the surface of the calibration block through the displacement sensor so as to determine the nominal pose of the coordinate system of the calibration block relative to the coordinate system of the machine base, determines the actual pose of the coordinate system of the calibration block relative to the coordinate system of the machine base based on the known relative position relation, and performs calibration correction on the kinematic parameters of the robot through the error of the comparison between the nominal pose and the actual pose.
8. The robot kinematics parameter calibration system based on single measurement according to claim 7, wherein,
the bottom plate is fixed on the working platform;
the base plate is provided with at least one mounting shaft, and the calibration block is provided with a mounting hole site corresponding to the mounting shaft;
the master control obtains the relative position relation between the calibration block and the robot according to the mechanical structure of the bottom plate.
9. The robot kinematic parameter calibration system based on single measurement according to claim 8, wherein the base plate is provided with three mounting shafts;
the three mounting shafts are uniformly distributed on the bottom plate;
the zero calibration device is used for calibrating the zero of the sensor;
the zero calibration device is arranged on the end effector in a key slot matching mode and props against the end part of the displacement sensor, zero calibration is carried out on the displacement sensor on the end effector, and the position length of the end part, which is away from the tail end of the robot, is measured when zero reading is obtained.
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