CN112276959B - Geometric parameter and joint zero position self-calibration method and device, electronic equipment and medium - Google Patents

Geometric parameter and joint zero position self-calibration method and device, electronic equipment and medium Download PDF

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CN112276959B
CN112276959B CN202011560013.6A CN202011560013A CN112276959B CN 112276959 B CN112276959 B CN 112276959B CN 202011560013 A CN202011560013 A CN 202011560013A CN 112276959 B CN112276959 B CN 112276959B
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error
joint
robot
foot
feet
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CN112276959A (en
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孔令雨
黄冠宇
高成志
谢也
谢安桓
张丹
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Zhejiang Lab
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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
    • B25J9/1628—Programme controls characterised by the control loop
    • B25J9/1653—Programme controls characterised by the control loop parameters identification, estimation, stiffness, accuracy, error analysis
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
    • B25J13/00—Controls for manipulators
    • 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
    • B25J9/1602—Programme controls characterised by the control system, structure, architecture
    • 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
    • B25J9/1602—Programme controls characterised by the control system, structure, architecture
    • B25J9/161—Hardware, e.g. neural networks, fuzzy logic, interfaces, processor
    • 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
    • B25J9/1656—Programme controls characterised by programming, planning systems for manipulators
    • B25J9/1664—Programme controls characterised by programming, planning systems for manipulators characterised by motion, path, trajectory planning

Abstract

The invention discloses a method, a device, electronic equipment and a medium for self-calibrating geometric parameters and a zero position of a joint, which can be particularly used for calibrating the size parameters of each component of a foot type robot and the zero position of a driving joint, and improving the positioning and control precision of the robot. The method comprises the steps of fixing the feet of the robot on a calibration plate with definite size parameters, adjusting the joint position of the robot, and calibrating the structure size parameters and the joint zero position of the robot on the basis of establishing a robot calibration model by using an inertia measurement unit and joint readings which are placed on the body of the robot. The invention has the advantages of low cost, simple and convenient operation and the like, and is suitable for calibrating the parameters of robots with different configurations and different leg and foot numbers.

Description

Geometric parameter and joint zero position self-calibration method and device, electronic equipment and medium
Technical Field
The invention relates to the field of robots and parameter identification, in particular to a method and a device for self-calibrating a geometric parameter and a joint zero position, electronic equipment and a medium.
Background
Among mobile robots, a legged robot has significant advantages in terrain adaptability, has the capabilities of walking on a complex ground, avoiding obstacles and the like, but has the problems of high control difficulty, poor motion stability and the like. The high-precision control of the foot robot is a key problem for realizing the stable motion of the foot robot. However, due to the influence of errors in machining, assembly and the like, geometric parameters, zero positions of kinematic joints and design values of the foot robot have deviations, and the robot is subjected to motion calculation on the basis, so that the pose deviation of the foot is inevitably caused. Therefore, the geometric parameters and the joint zero position of the foot type robot need to be calibrated, the positioning accuracy of the foot is improved, and a foundation is laid for the stable control of the robot.
The search of the prior art shows that the prior art has fewer calibrating means for the geometric parameters and the zero position of the joint of the foot type robot, and a few technical means in the aspect are mostly used for calibrating the driving joint in the robot, so that the overall consideration is lacked, and the positioning error caused by the size parameters of the component is difficult to compensate by a control system. For example, chinese patent application publication No. CN110374961A discloses a self-calibration device and a calibration method for a foot-type robot hydraulic actuator, which are used to calibrate a driving system of a robot individually; chinese patent application publication No. CN107065558A discloses a hexapod robot joint angle calibration method based on body attitude angle correction, which is used for calibrating joint angle deviation of a hexapod robot.
Disclosure of Invention
The embodiment of the invention aims to provide a geometric parameter and joint zero position self-calibration method, a device, electronic equipment and a medium, so as to at least solve the problems of incomplete calibration parameter consideration and poor calibration method universality in the related technology.
In order to achieve the above purpose, the technical solution adopted by the embodiment of the present invention is as follows:
according to a first aspect of the embodiments of the present invention, there is provided a geometric parameter and joint zero position self-calibration method for a foot robot, the method including: acquiring posture and joint position data of the body of the legged robot, wherein the feet of the legged robot are fixed on a calibration plate; respectively constructing a kinematic forward solution model between the body and the foot of the foot type robot, a first posture error model between the body and the foot of the foot type robot and a second posture error model between the feet of the foot type robot according to the posture and the joint position data, wherein the kinematic forward solution model is used for solving the corresponding foot posture according to the posture and the joint position data, and the first posture error model is used for describing the transmission relation between the corresponding leg connecting rod size error and the zero position error of the moving joint to the foot posture error; the second pose error model is used for describing pose error relations among different feet, which are influenced by geometric parameter deviations of corresponding legs and zero deviations of joints; and identifying and calculating the geometric parameters and the zero positions of the joints of the foot type robot by using the postures and joint position data of the foot type robot under multiple groups of postures based on the kinematics positive solution model, the first posture error model and the second posture error model until the residual error converges to a given threshold value or the iterative calculation converges, and finally obtaining the zero positions and the geometric parameters of the joints.
According to a second aspect of the embodiments of the present invention, there is provided a geometric parameter and joint zero position self-calibration apparatus for a legged robot, including: an acquisition unit for acquiring posture and joint position data of a body of a legged robot mounted on a calibration board; the model building unit is used for respectively building a kinematic positive solution model between the body and the foot of the foot type robot, a first position error model between the body and the foot of the foot type robot and a second position error model between the feet of the foot type robot according to the posture and the joint position data, wherein the kinematic positive solution model is used for solving the corresponding foot position and posture according to the posture of the body and the joint position data, and the first position error model is used for describing the transfer relationship from the corresponding leg connecting rod size error and the zero position error of the moving joint to the foot position and posture error; the second pose error model is used for describing pose error relations among different feet, which are influenced by geometric parameter deviations of corresponding legs and zero deviations of joints; and the calculation unit is used for identifying and calculating the geometric parameters and the joint zero position of the foot type robot by utilizing the postures and the joint position data of the foot type robot under multiple groups of posture shapes based on the kinematics positive solution model, the first posture error model and the second posture error model until the residual error converges to a given threshold value, and finally obtaining the joint zero position and the geometric parameters.
According to a third aspect of embodiments of the present invention, there is provided an electronic apparatus, including: one or more processors; a memory for storing one or more programs; when executed by the one or more processors, cause the one or more processors to implement a method as described in the first aspect.
According to a fourth aspect of embodiments of the present invention, there is provided a computer-readable storage medium having stored thereon a computer program which, when executed by a processor, implements the method according to the first aspect.
According to the technical scheme, the embodiment of the invention has the following beneficial effects: under the condition of only depending on one calibration plate, the established transfer relation model of the zero position error of the geometry and the joint and the pose error can simultaneously consider the influence of the geometric dimension error of a robot member and the zero position error of a driving joint on the positioning precision of the robot, under the condition of acquiring body postures and joint position information of the robot under a plurality of configurations, the geometric parameters of the robot member and the zero position self-calibration of the driving joint can be synchronously completed, and the positioning precision of the feet of the robot can be improved and the motion control effect of the robot can be improved by compensating the calibrated result into a control system.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention and not to limit the invention. In the drawings:
FIG. 1 is a flow chart illustrating a method for geometric parameter and joint null self-calibration in accordance with an exemplary embodiment.
Fig. 2 is a schematic diagram of a biped robot configuration shown in accordance with an exemplary embodiment.
FIG. 3 is a schematic diagram of a calibration plate shown in accordance with an exemplary embodiment.
Fig. 4 is a schematic diagram of a biped robot configuration shown in accordance with an exemplary embodiment.
FIG. 5 is a flow chart illustrating the calculation of the geometry and joint null identification according to an exemplary embodiment.
FIG. 6 is a block diagram illustrating a geometry and joint null self-calibration arrangement in accordance with an exemplary embodiment.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments, and the objects and effects of the present invention will become more apparent, and the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Example 1:
fig. 1 is a flowchart illustrating a geometric parameter and joint zero position self-calibration method according to an exemplary embodiment, and referring to fig. 1, the present embodiment provides a geometric parameter and joint zero position self-calibration method for a foot robot, which is used for geometric parameter and joint zero position self-calibration, and includes the following steps:
step S101, acquiring body posture and joint position data of a legged robot, wherein the legged robot is installed on a calibration plate 2;
specifically, fig. 2 is a schematic view showing a biped robot structure according to an exemplary embodiment, fig. 3 is a schematic view showing a calibration plate according to an exemplary embodiment, and fig. 4 is a schematic view showing a biped robot structure according to an exemplary embodiment. The calibration plate is provided with positioning parts which are the same as the foot parts of the foot type robot in number, are used for connecting the foot parts of the foot type robot and calibrate the position relation of the foot parts. The foot type robot forms include, but are not limited to, biped, quadruped, hexapod and other configurations, and the foot and the body are connected in sequence through a kinematic joint and a connecting rod; taking a biped robot as an example, as shown in fig. 1-3, a body 7 of the biped robot is respectively connected with a left foot part 14 and a right foot part 16 through a first kinematic joint 8, a second kinematic joint 9, a third kinematic joint 10, a first connecting rod 11, a fourth kinematic joint 12, a second connecting rod 13 and a fifth kinematic joint 15 in sequence, wherein the first kinematic joint 8, the second kinematic joint 9 and the third kinematic joint 10 integrally form a hip joint of the biped robot, the fourth kinematic joint 12 is a knee joint, and the fifth kinematic joint 15 is an ankle joint; the calibration plate is provided with a first positioning part 3 and a second positioning part 5 which are processed with high precision and are used for connecting the robot feet, the number of the first positioning part 3 and the second positioning part 5 is the same as that of the robot feet, a left foot coordinate system 4 and a right foot coordinate system 6 are respectively established on the first positioning part 3 and the second positioning part 5, and the first positioning part 3 and the second positioning part 5 have accurate position relation and are obtained by including but not limited toThe bolt is connected with the left foot part 14 and the right foot part 16 of the robot in a rigid mode. And defining a coordinate system
Figure 260876DEST_PATH_IMAGE001
Relative to
Figure 646858DEST_PATH_IMAGE002
Has accurate pose relation
Figure 144704DEST_PATH_IMAGE003
。
Before acquiring the posture and joint position data of the body of the legged robot, the feet of the legged robot need to be installed on the calibration board, wherein the step of acquiring the posture data of the body of the legged robot comprises the following steps:
reading body posture information of the legged robot through a sensor, wherein the sensor comprises but is not limited to an inertial measurement unit; defining coordinates of body gestures read by a sensor relative to a global coordinate system
Figure 8755DEST_PATH_IMAGE004
Comprises the following steps:
Figure 291969DEST_PATH_IMAGE005
wherein the content of the first and second substances,
Figure 380010DEST_PATH_IMAGE006
respectively representing the rotation RPY Euler angles of the body coordinate system of the legged robot relative to the global coordinate system, and then representing the attitude matrix of the body coordinate system relative to the global coordinate system
Figure 115885DEST_PATH_IMAGE007
Expressed as:
Figure 38754DEST_PATH_IMAGE008
wherein the content of the first and second substances,
Figure 176474DEST_PATH_IMAGE009
indicating edgexRotation of the shaft
Figure 638680DEST_PATH_IMAGE010
The attitude matrix of the angle is then used,
Figure 861851DEST_PATH_IMAGE011
indicating edgezRotation of the shaft
Figure 51392DEST_PATH_IMAGE012
The attitude matrix of the angle is then used,
Figure 43619DEST_PATH_IMAGE013
indicating edgeyRotation of the shaft
Figure 942305DEST_PATH_IMAGE014
An attitude matrix of angles;
Figure 652772DEST_PATH_IMAGE015
，
Figure 646005DEST_PATH_IMAGE016
，
Figure 555055DEST_PATH_IMAGE017
，
Figure 359063DEST_PATH_IMAGE018
，
Figure 556826DEST_PATH_IMAGE019
，
Figure 104482DEST_PATH_IMAGE020
respectively represent
Figure 320569DEST_PATH_IMAGE021
，
Figure 561057DEST_PATH_IMAGE022
Abbreviations of (a);
defining a position vector of a robot body coordinate system relative to a global coordinate system
Figure 980537DEST_PATH_IMAGE023
Comprises the following steps:
Figure 66305DEST_PATH_IMAGE024
wherein the content of the first and second substances,x、y、zrespectively representing the body coordinate system of the robot relative to the global coordinate systemx、y、zPosition coordinates in the axial direction.
The method comprises the following steps of acquiring joint position data of a body of the legged robot, wherein the steps comprise:
reading of foot robot by sensors mounted on kinematic jointsiKinematic joint position information for a bar leg, including but not limited to encoders, grating scales, etc.; and the position information of the moving joint in each leg
Figure 136898DEST_PATH_IMAGE025
Merge and write into vector form:
Figure 548288DEST_PATH_IMAGE026
wherein
Figure 455064DEST_PATH_IMAGE027
Is shown asiThe leg is firstnIndividual kinematic joint position information.
Step S102, respectively constructing a kinematic forward solution model between the body and the foot of the foot type robot, a first posture error model between the body and the foot of the foot type robot and a second posture error model between the feet of the foot type robot according to the posture and the joint position data, wherein the kinematic forward solution model is used for solving the corresponding foot posture according to the body posture and the joint position data, and the first posture error model is used for describing the transfer relationship between the corresponding leg connecting rod size error and the zero position error of the moving joint to the foot posture error; the second pose error model is used for describing pose error relations among different feet, which are influenced by geometric parameter deviations of corresponding legs and zero deviations of joints;
specifically, a step of constructing a kinematics forward solution model between the body and the foot of the legged robot, where the modeling method of the kinematics forward solution model includes, but is not limited to, a closed-loop vector method, a D-H parameter method, and an exponential product method, and the following methods are taken as examples in this example, and include:
and for each leg, deducing the position and posture information of the corresponding foot relative to a coordinate system of the body of the robot according to the geometric dimension parameters of the leg component of the robot and the position information of the motion joint.
For the firstiThe kinematics forward model between the body and the foot of the legged robot is expressed as:
Figure 141260DEST_PATH_IMAGE028
wherein the content of the first and second substances,
Figure 82671DEST_PATH_IMAGE029
representing a positive kinematics solution function between the body and the foot of the legged robot;
Figure 914230DEST_PATH_IMAGE030
is shown asiThe pose vector of an individual foot with respect to the global coordinate system is made up of position and pose vectors, i.e.
Figure 42723DEST_PATH_IMAGE031
Wherein
Figure 1451DEST_PATH_IMAGE032
And
Figure 266211DEST_PATH_IMAGE033
are respectively provided withIs shown asiThe position and attitude vectors of the individual foot relative to the global coordinate system,
Figure 268671DEST_PATH_IMAGE034
the position component is represented by a representation of,
Figure 150039DEST_PATH_IMAGE035
representing the euler angles describing the pose;
Figure 443617DEST_PATH_IMAGE036
is shown asiA vector formed by geometric parameters of each member in the strip leg;
Figure 94041DEST_PATH_IMAGE037
and representing the pose vector of the body coordinate system of the foot type robot relative to the global coordinate system.
The method comprises the following steps of constructing a first posture error model between the body and the foot of the foot type robot, wherein the step comprises the following steps:
for each leg, according to the geometric dimension parameters of the leg component of the robot and the position information of the motion joint, constructing a transfer relation between the geometric dimension error of the leg component and the zero offset of the motion joint to the corresponding attitude offset of the foot, wherein the transfer relation is a first attitude error model.
Specifically, the attitude error model between the body and the foot of the legged robot is expressed as:
Figure 752556DEST_PATH_IMAGE038
wherein the content of the first and second substances,
Figure 370488DEST_PATH_IMAGE039
representing the deviation between the theoretical and actual pose of the foot,
Figure 139861DEST_PATH_IMAGE040
to represent
Figure 910371DEST_PATH_IMAGE041
The corresponding error parameter is set to be,
Figure 739786DEST_PATH_IMAGE042
is as followsiZero offset of the joints in the leg,
Figure 862593DEST_PATH_IMAGE043
respectively represent
Figure 701236DEST_PATH_IMAGE044
A transfer relation matrix of the foot pose deviation;
the first attitude error model, which is finally used for calibration, except for the parameters related to the position error, is represented as:
Figure 60673DEST_PATH_IMAGE045
wherein the content of the first and second substances,
Figure 123307DEST_PATH_IMAGE046
representing the attitude vector of the foot positioning device on the calibration board under the global coordinate system,
Figure 200984DEST_PATH_IMAGE047
the pose vector of the foot with respect to the global coordinate system obtained by the kinematic calculation,
Figure 92586DEST_PATH_IMAGE048
respectively representing a 3-dimensional identity matrix and a three-dimensional zero matrix.
The step of constructing a second attitude error model between the feet of the foot robot comprises the following steps:
the method comprises the steps of obtaining a preset real pose relation of two feet through a calibration plate, obtaining a theoretical pose relation of the corresponding feet by utilizing a kinematics forward model of legs corresponding to the two feet, and constructing a transfer relation from a geometric parameter error of the corresponding legs and a zero position error of a joint to a pose error of the feet by taking the minimum difference value of the real pose and the theoretical pose of the two feet as an optimization target, wherein the transfer relation is a second pose error model.
Specifically, the pose error model between the feet is expressed as:
Figure 306529DEST_PATH_IMAGE049
wherein the content of the first and second substances,
Figure 743327DEST_PATH_IMAGE050
a homogeneous transformation matrix representing the body relative to a world coordinate system,
Figure 308300DEST_PATH_IMAGE051
is shown asiA homogeneous transformation matrix of the position and posture of each foot relative to a body coordinate system,
Figure 738014DEST_PATH_IMAGE052
Figure 868781DEST_PATH_IMAGE053
respectively representiThe attitude matrix and the position vector of each foot relative to the body coordinate system;
Figure 476479DEST_PATH_IMAGE054
is shown asjThe foot part is opposite to the firstiThe deviation between the actual value and the theoretical value in the pose relationship of each foot,
Figure 528749DEST_PATH_IMAGE055
representing the alignment plate midfootjRelative to footiThe pose relation vector of (2) is the design value of the calibration board,
Figure 247306DEST_PATH_IMAGE056
representing the calculation of the positive solution of kinematics to obtain the footjRelative to footiThe pose-relation vector of (a) is,
Figure 685110DEST_PATH_IMAGE057
the corresponding homogeneous transformation matrix may be passed
Figure 463710DEST_PATH_IMAGE058
Calculating to obtain;
Figure 3276DEST_PATH_IMAGE059
in the second attitude error model, function
Figure 322262DEST_PATH_IMAGE060
Representing homogeneous transformation matrices
Figure 630883DEST_PATH_IMAGE061
The accompanying characterization of (a) and (b),
Figure 829652DEST_PATH_IMAGE062
wherein the content of the first and second substances,
Figure 590935DEST_PATH_IMAGE063
as a position vector
Figure 916874DEST_PATH_IMAGE064
Is characterized by the antisymmetric matrix written as:
Figure 814423DEST_PATH_IMAGE065
x、y、zrespectively representing three-dimensional vectors
Figure 184093DEST_PATH_IMAGE066
Of (1). In the second attitude error model
Figure 698251DEST_PATH_IMAGE067
Respectively represent
Figure 562302DEST_PATH_IMAGE068
A transfer relation matrix of the foot pose deviation,
Figure 579936DEST_PATH_IMAGE069
to represent
Figure 386087DEST_PATH_IMAGE070
The corresponding error parameter is set to be,
Figure 918700DEST_PATH_IMAGE071
is composed of
Figure 586442DEST_PATH_IMAGE072
Corresponding zero offset.
Furthermore, to ensure linear independence of the error transfer matrix in the attitude error model, it is common toi、jSelection of adjacent legs, i.e. assuming roboticsnFoot, then existn-1 interfoot pose error model; different from the foot error model, the calibration board has high-precision pose relationship among the feet, and
Figure 458583DEST_PATH_IMAGE073
the error model of (1) describes the pose relationship between two feet, and actually does not contain the position and posture information of the body of the legged robot, so that the position and posture information of the legged robot is not included in the error model
Figure 186367DEST_PATH_IMAGE073
The six-dimensional pose error parameters are all available. Writing first attitude error models and second attitude error models corresponding to all legs in the foot robot into a matrix form to obtain an error model for self-calibration of geometric parameters and joint zero positions of the foot robot, and finally writing the following form:
Figure 658806DEST_PATH_IMAGE074
wherein the content of the first and second substances,
Figure 599080DEST_PATH_IMAGE075
by
Figure 591307DEST_PATH_IMAGE076
And
Figure 489992DEST_PATH_IMAGE077
the structure of the utility model is that the material,
Figure 731618DEST_PATH_IMAGE078
and
Figure 996289DEST_PATH_IMAGE079
to correspond to
Figure 108602DEST_PATH_IMAGE080
And
Figure 912610DEST_PATH_IMAGE081
combinations of (a) and (b).
The step S103 will be described in further detail below by taking a bipedal robot as an example.
In the embodiment, the kinematics forward solution model of the legged robot is constructed by a D-H parameter method. Considering the fact that the traditional D-H parameters are singular when the pose error model is constructed and when the axes of adjacent joints are parallel, an improved D-H method (used when the axes of adjacent joints are not parallel) and a Hayati model (used when the axes of adjacent joints are parallel) are respectively constructed, and finally, the kinematics positive solution model in the embodiment totally comprises 3 types of pose transfer models for describing the states of adjacent members, namely:
Figure 844794DEST_PATH_IMAGE082
wherein the content of the first and second substances,
Figure 641717DEST_PATH_IMAGE083
and
Figure 608536DEST_PATH_IMAGE084
representing translation and rotation transformations, respectively, the first variable in brackets representing the reference axis of motion and the second variable representing the specific amount of motion;
Figure 583445DEST_PATH_IMAGE085
representing the pose transfer relationship of the body coordinate system to the first kinematic joint 8,a、b、cindicating the amount of translation along the corresponding axis,
Figure 268505DEST_PATH_IMAGE086
indicating the amount of rotation along the corresponding axis,
Figure 416589DEST_PATH_IMAGE087
represents the amount of movement of the kinematic joint 8;
Figure 487182DEST_PATH_IMAGE088
representing the posture transformation relation between coordinate systems described by the improved D-H method,
Figure 898572DEST_PATH_IMAGE089
、a、
Figure 805348DEST_PATH_IMAGE090
、
Figure 694807DEST_PATH_IMAGE091
represents the corresponding D-H parameter;
Figure 885486DEST_PATH_IMAGE092
representing the posture transformation relation among coordinate systems described by the Hayati model,
Figure 202197DEST_PATH_IMAGE093
represents the corresponding D-H parameter; according to the geometrical relationship of the adjacent joints of the legged robot in the embodiment, the forward kinematic model of the legged robot can be obtained as follows:
Figure 330690DEST_PATH_IMAGE094
wherein the function
Figure 23840DEST_PATH_IMAGE095
Representing a homogeneous transformation matrix
Figure 69025DEST_PATH_IMAGE096
Converting into a function of corresponding Euler angles and position coordinates; the corresponding D-H parameters are defined as shown in Table 1. It can be seen that each leg of the robot contains 21 geometric parameters and 5 joint zero-position parameters, so that the total number of parameters to be calibrated is 52, that is, at least 6 positions are required to realize calibration calculation of the robot. However, in general, to ensure a sufficiently good calibration effect, the number of patterns used for calibration is preferably much larger than the minimum number required, and covers the entire working space of the robot as much as possible.
Table 1: D-H parameters for kinematic positive solutions in the examples
Figure 822218DEST_PATH_IMAGE097
Wherein the content of the first and second substances,
Figure 703586DEST_PATH_IMAGE098
respectively representiIn the leg, the body is connected to the joint 8, the joint 8 is connected to the joint 9, the joint 9 is connected to the joint 10, the joint 10 is connected to the joint 12, the joint 12 is connected to the joint 15, the lower corner mark letter represents the adopted specific D-H modeling method, and the subsequent parameters are parameters in the corresponding method, and specifically comprise geometric parameters, joint zero position parameters and joint motion parameters.
The first and second attitude error models of the robot are constructed based on the error transfer relationship between adjacent members or motion joint coordinate systems
Figure 731585DEST_PATH_IMAGE099
The pose error model corresponding to the pose error model can be written as:
Figure 382009DEST_PATH_IMAGE100
wherein the content of the first and second substances,
Figure 555370DEST_PATH_IMAGE101
which is indicative of the error of the corresponding geometric parameter,
Figure 924035DEST_PATH_IMAGE102
indicating a joint null. The concrete expression of the transmission relation between the geometric and joint zero offset and the pose error can be obtained by the following formula
Figure 958987DEST_PATH_IMAGE103
On the basis, the first attitude error model of the foot robot can be written as follows:
Figure 463917DEST_PATH_IMAGE104
wherein the content of the first and second substances,
Figure 542601DEST_PATH_IMAGE105
in the above formula, the first and second carbon atoms are,
Figure 398561DEST_PATH_IMAGE106
is a 6-dimensional unit matrix and is,
Figure 971625DEST_PATH_IMAGE107
the matrix in (1) can be obtained according to the corresponding geometric, joint zero offset and pose error transfer relationship matrix.
From the above results, a second posture error transfer model between foot 14 and foot 16 can be obtained as:
Figure 596641DEST_PATH_IMAGE108
and combining the two error models to obtain an error model for self-calibration of the geometric parameters and the zero position of the joint of the foot robot:
Figure 111805DEST_PATH_IMAGE109
wherein, each part in the error model can be written as:
Figure 189483DEST_PATH_IMAGE110
and step S103, identifying and calculating geometric parameters and joint zero positions of the foot type robot by using the postures and joint position data of the foot type robot under multiple sets of posture forms based on the kinematics positive solution model, the first posture error model and the second posture error model until the residual error converges to a given threshold value or converges, wherein the finally obtained joint zero position and geometric parameters are calibration results. FIG. 5 is a flow chart illustrating the calculation of the geometry and joint null identification according to an exemplary embodiment. The specific process can be seen with reference to fig. 5 and described below:
(1) beginning: completing preparation work, including 1) establishing a kinematics positive solution model of the robot, a first position and posture error model and a second position and posture error model; 2) respectively fixing the left foot part and the right foot part of the robot on a first positioning part 3 and a second positioning part 5 of a calibration plate, and ensuring that the calibration plate is in a static state relative to a global coordinate system; 3) measuring an attitude vector of a foot immobilization device using an inertial measurement unit
Figure 831817DEST_PATH_IMAGE111
And obtaining the pose vector of the foot fixing device 2 on the calibration plate relative to the position vector 1 through a design drawing
Figure 311340DEST_PATH_IMAGE112
；
(2) Nominal geometry and joint zero position parameter definition of the robot: determining theoretical (nominal) geometry and joint zero position parameters of the robot, wherein the values are initial values of parameter identification calculation when the robot performs calibration;
(3) obtaining calibration experiment data: controlling the foot robot to move to different configurations, and measuring the joint position information after the foot robot is stationary
Figure 544875DEST_PATH_IMAGE113
And body posture
Figure 353257DEST_PATH_IMAGE114
(ii) a According to the first and second attitude error models in the invention, each attitude can be obtained
Figure 268123DEST_PATH_IMAGE115
The basic requirement of calibration is that the number of the constraint equations is not less than the number of geometric and joint zero parameters to be calibrated;
(4) and (3) calculating a calibration model under the current parameters: calculated through a kinematics positive solution model of the robotmPose vectors of two feet under the configuration relative to a world coordinate system
Figure 867732DEST_PATH_IMAGE116
(ii) a On the basis, according to the first and second attitude error models, a model for calibrating iterative computation can be obtained, namely:
Figure 475430DEST_PATH_IMAGE118
wherein, the lower corner markkIndicating that the model is in the second placekIn the secondary iteration calculation process, the geometric and joint zero position parameters in the model are the machine in the first iterationDesign values of the robot.
(5) Deviation evaluation: judging whether the actual precision requirement is met or not according to the calculated deviation value, and finishing calibration if the actual precision requirement is met; if not, performing parameter identification calculation;
(6) and (3) parameter identification and calculation:
Figure 511388DEST_PATH_IMAGE119
(7) updating geometric and joint zero parameters:
Figure 229946DEST_PATH_IMAGE120
(8) calculating the positive solution of the robot kinematics under the current parameters: after the geometric and joint zero position parameters of the robot are updated, the pose vectors of the two feet relative to the world coordinate system under all the calibration poses are recalculated
Figure 684061DEST_PATH_IMAGE121
；
(9) And (5) repeating the processes (4) to (8) until the deviation evaluation requirement is met or the iterative calculation is converged, namely completing the whole calibration process, and finally obtaining the geometric and joint zero position parameters which are the calibration result.
Corresponding to the embodiment of the geometric parameter and joint zero position self-calibration method, the application also provides an embodiment of a geometric parameter and joint zero position self-calibration device. FIG. 6 is a block diagram illustrating a geometry and joint null self-calibration apparatus for a legged robot, according to an exemplary embodiment, comprising:
an acquisition unit 21 for said acquiring posture and joint position data of a body of a legged robot mounted on a calibration board;
the model building unit 22 is configured to respectively build a kinematic forward solution model between the body and the foot of the foot robot, a first posture error model between the body and the foot of the foot robot, and a second posture error model between the feet of the foot robot according to the posture and the joint position data, where the kinematic forward solution model is configured to solve the corresponding foot posture according to the posture of the body and the joint position data, and the first posture error model is configured to describe a transfer relationship between the corresponding leg link size error and the zero position error of the moving joint to the foot posture error; the second pose error model is used for describing pose error relations among different feet, which are influenced by geometric parameter deviations of corresponding legs and zero deviations of joints;
and the calculating unit 23 is configured to perform identification calculation on the geometric parameters and the joint zero position of the foot robot by using the postures and joint position data of the foot robot under multiple sets of posture shapes based on the kinematic positive solution model, the first posture error model and the second posture error model until a residual error converges to a given threshold value, and finally obtain the joint zero position and the geometric parameters.
The above-mentioned serial numbers of the embodiments of the present invention are merely for description and do not represent the merits of the embodiments.
In the above embodiments of the present invention, the descriptions of the respective embodiments have respective emphasis, and for parts that are not described in detail in a certain embodiment, reference may be made to related descriptions of other embodiments.
In the embodiments provided in the present application, it should be understood that the disclosed technology can be implemented in other ways. The above-described device embodiments are merely illustrative, and for example, the division of the units may be a logical division, and in actual implementation, there may be another division, for example, multiple units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, units or modules, and may be in an electrical or other form.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.
The integrated unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a removable hard disk, a magnetic or optical disk, and other various media capable of storing program codes.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims (10)

1. A geometric parameter and joint zero position self-calibration method is used for geometric parameter and joint zero position self-calibration of a foot robot, and is characterized by comprising the following steps:
acquiring posture and joint position data of the body of the legged robot, wherein the feet of the legged robot are fixed on a calibration plate;
respectively constructing a kinematic forward solution model between the body and the feet of the foot type robot, a first posture error model between the body and the feet of the foot type robot and a second posture error model between the feet of the foot type robot according to the posture and joint position data of the body, wherein the kinematic forward solution model is used for solving the corresponding foot posture according to the posture and joint position data of the body, and the first posture error model is used for describing the transmission relationship between the size error of the corresponding leg connecting rod and the zero position error of the kinematic joint to the foot posture error; the second posture error model is used for describing the posture error relationship among different feet, which is influenced by the size error of the corresponding leg connecting rod and the zero error of the movement joint;
and identifying and calculating the geometric parameters and the zero positions of the joints of the foot type robot by using the postures of the body of the foot type robot under multiple groups of postures and joint position data based on the kinematics positive solution model, the first posture error model and the second posture error model until the residual error converges to a given threshold value or the iterative calculation converges, and finally obtaining the zero positions and the geometric parameters of the joints.
2. The method for self-calibration of geometric parameters and zero positions of joints according to claim 1, wherein the calibration plate is provided with positioning parts, the number of which is the same as that of the feet of the legged robot, for connecting the feet of the legged robot and calibrating the position relation of the feet.
3. The method for zero position self-calibration of geometric parameters and joints according to claim 1, wherein the step of constructing the first position error model from the body to the foot of the legged robot comprises:
for each leg, according to the geometric dimension parameters of the leg component of the robot and the position information of the motion joint, a transfer relation from the dimension error of the leg connecting rod of the leg component and the zero position error of the motion joint to the corresponding foot pose error is constructed, and the transfer relation is a first pose error model.
4. The method for zero position self-calibration of geometric parameters and joints according to claim 1, wherein the step of constructing a second attitude error model between the feet of the legged robot comprises:
and obtaining the real pose relations of two preset feet through a calibration plate, simultaneously obtaining the theoretical pose relations of the two feet by utilizing the kinematics forward solution model, and constructing a transfer relation from the corresponding leg connecting rod size error and the zero position error of the movement joint to the foot pose error by taking the minimum difference value between the real pose and the theoretical pose of the two feet as an optimization target, wherein the transfer relation is a second pose error model.
5. A geometrical parameter and joint zero position self-calibration device, which is used for a foot type robot, is characterized by comprising:
an acquisition unit for acquiring posture and joint position data of the body of the legged robot, wherein the feet of the legged robot are fixed on a calibration plate;
the model building unit is used for respectively building a kinematic positive solution model between the body and the feet of the foot type robot, a first position error model between the body and the feet of the foot type robot and a second position error model between the feet of the foot type robot according to the posture of the body and the joint position data, wherein the kinematic positive solution model is used for solving the corresponding foot position and posture according to the posture of the body and the joint position data, and the first position error model is used for describing the transfer relationship between the corresponding leg connecting rod size error and the zero position error of the kinematic joint and the foot position and posture error; the second posture error model is used for describing the posture error relationship among different feet, which is influenced by the size error of the corresponding leg connecting rod and the zero error of the movement joint;
and the calculation unit is used for identifying and calculating the geometric parameters and the zero positions of the joints of the foot type robot by utilizing the postures of the body of the foot type robot under multiple groups of posture and joint position data based on the kinematics positive solution model, the first posture error model and the second posture error model until the residual error converges to a given threshold value, and finally obtaining the zero positions and the geometric parameters of the joints.
6. The device for automatically calibrating geometric parameters and zero positions of joints according to claim 5, wherein the calibration plate is provided with positioning parts which are as many as the feet of the legged robot, are used for connecting the feet of the legged robot, and calibrate the position relation of the feet.
7. The device for self-calibration of geometric parameters and zero position of joints according to claim 5, wherein constructing a first position error model between the body and the foot of the legged robot comprises:
for each leg, according to the geometric dimension parameters of the leg component of the robot and the position information of the motion joint, a transfer relation from the dimension error of the leg connecting rod of the leg component and the zero position error of the motion joint to the corresponding foot pose error is constructed, and the transfer relation is a first pose error model.
8. The device for self-calibration of geometric parameters and zero position of joints according to claim 5, wherein constructing a second model of attitude errors between feet of the legged robot comprises:
and obtaining the real pose relations of two preset feet through a calibration plate, simultaneously obtaining the theoretical pose relations of the two feet by utilizing the kinematics forward solution model, and constructing a transfer relation from the corresponding leg connecting rod size error and the zero position error of the movement joint to the foot pose error by taking the minimum difference value between the real pose and the theoretical pose of the two feet as an optimization target, wherein the transfer relation is a second pose error model.
9. An electronic device, comprising:
one or more processors;
a memory for storing one or more programs;
the one or more programs, when executed by the one or more processors, cause the one or more processors to implement the method of any of claims 1-4.
10. A computer-readable storage medium, on which a computer program is stored which, when being executed by a processor, carries out the method according to any one of claims 1-4.
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