CN109822574B - Industrial robot end six-dimensional force sensor calibration method - Google Patents
Industrial robot end six-dimensional force sensor calibration method Download PDFInfo
- Publication number
- CN109822574B CN109822574B CN201910213295.3A CN201910213295A CN109822574B CN 109822574 B CN109822574 B CN 109822574B CN 201910213295 A CN201910213295 A CN 201910213295A CN 109822574 B CN109822574 B CN 109822574B
- Authority
- CN
- China
- Prior art keywords
- sensor
- force
- axis
- moment
- relational expression
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Landscapes
- Force Measurement Appropriate To Specific Purposes (AREA)
- Manipulator (AREA)
Abstract
The invention belongs to the field of industrial robot calibration and discloses a method for calibrating a six-dimensional force sensor at the tail end of an industrial robot. The method comprises the following steps: (a) in the measuring process of the six-dimensional force sensor, a relational expression about the force, the moment and the displacement measured on the sensor is constructed, and a relational expression between the zero values of the force and the moment on the sensor and the mass center of the load tool is constructed; (b) acquiring data of force and moment measured by the six-dimensional force sensor under a plurality of postures, and calculating by adopting a least square method to obtain zero values of the force and the moment of the six-dimensional sensor; (c) constructing a relational expression about the gravity of the load tool and calculating; (d) and (4) constructing a relational expression of a mounting angle of the sensor coordinate system and the end flange coordinate system along the Z axis and calculating the relational expression. By the method and the device, the calibration time is shortened, and the measurement precision is improved after the calibration result is compensated.
Description
Technical Field
The invention belongs to the field of industrial robot calibration, and particularly relates to a method for calibrating a six-dimensional force sensor at the tail end of an industrial robot.
Background
Industrial robots are widely used in various fields of industrial production, and in some work tasks (such as grinding, polishing, assembling and the like) requiring industrial robots to be in contact with the environment, the requirement of the tasks cannot be met by pure position control, for example, in grinding applications, a high-rigidity robot may cause damage to a ground workpiece when performing position control. Therefore, the robot is required to have the function of controlling the contact force with the environment. The existing implementation scheme is that a six-dimensional force sensor is generally arranged at the tail end of a robot and used for measuring the stress condition of a tool at the tail end of the robot in the working process so as to complete force control.
The six-dimensional force sensor is usually installed at the tail end of the robot and used for measuring the stress information of the tail end in the working process of the robot, as shown in fig. 2. The six-dimensional force sensor has an inherent coordinate system and can measure three-dimensional orthogonal force and three-dimensional orthogonal moment in the coordinate system. When the six-dimensional force sensor is powered on, the reading of each axis of the six-dimensional force sensor is not zero, and the reading is called the zero point of the sensor. The sensor zero point is different in size after being electrified every time, so that a certain method is needed for calculating the sensor reading zero point after the load tool is installed.
The force and moment measured by the six-dimensional force sensor not only comprise a zero point, but also comprise force and moment components of the gravity of the load tool on each axis, and the components of the gravity of the load tool on each axis are different under different postures. It is therefore necessary to know the tool gravity and then calculate the component in each axis from the robot pose and subtract the load tool gravity component from the sensor readings. Thereby eliminating the influence of the self-gravity of the load tool on the measurement result. The data directly measured by the six-dimensional force sensor is based on a coordinate system of the six-dimensional force sensor, the industrial robot also has an inherent coordinate system of the industrial robot, the coordinate system of the industrial robot comprises a base coordinate system and a terminal flange coordinate system, the six-dimensional force sensor is mounted on a terminal flange of the industrial robot, the Z axis of the sensor coordinate system and the Z axis of the terminal flange coordinate system can be ensured to be coaxial through a mechanical connecting piece, but the mounting angle of the Z axis between the sensor coordinate system and the terminal flange coordinate system cannot be ensured. The reference frame of the robot during operation is the end flange coordinate system, i.e. the tool coordinate system, and because of the sensor mounting angle, the force and moment measurements on the X and Y axes of the sensors are not the forces experienced on the X and Y axes of the end tool. The installation angle of the sensor needs to be known and then the rotation conversion is carried out, so that the robot needs to be capable of calibrating the installation angle of the sensor. In the prior art, the calibration of the zero point of a sensor and the gravity of a tool needs to be carried out, and the robot needs to be controlled to reach some specified postures to finish the calibration. And the variation between these poses is large, requiring a certain time to change from one pose to another. And the calibration of the sensor mounting angle cannot be carried out.
Disclosure of Invention
Aiming at the defects or improvement requirements of the prior art, the invention provides a method for calibrating a six-dimensional force sensor at the tail end of an industrial robot, which comprises the steps of solving a relational expression of the gravity of a load tool, the zero point of the sensor and the installation angle of the sensor, then acquiring the force, the moment and the joint angle of the sensor under different postures, and carrying out least square solution, so as to realize the calibration of the six-dimensional force sensor, and obtaining a real measured value according to the calibrated value and the reading of the actual sensor, thereby reducing the reading error of the six-dimensional force sensor of the robot.
In order to achieve the above object, according to the present invention, there is provided a method for calibrating a six-dimensional force sensor at an end of an industrial robot, the method comprising the steps of:
(a) in the measuring process of the six-dimensional force sensor, a relational expression (I) about the force, the moment and the displacement measured on the sensor is constructed according to the force and the moment of the load tool measured by the sensor, and a relational expression (II) about the zero values of the force and the moment on the sensor and the mass center of the load tool is constructed according to the relational expression;
(b) acquiring data of force and moment measured by a six-dimensional force sensor under r multiplied by s postures, wherein each r data is a group of data, s groups of data are obtained, s displacements are calculated according to a relational expression (I) by utilizing the s groups of data, and the s displacements are combined with the relational expression (II) for calculation to obtain zero values of the force and the moment of the six-dimensional sensor;
(c) constructing a relational expression (III) of the zero values of the six-dimensional sensor force and the moment and the gravity of the load tool according to the relationship between the zero values and the gravity of the load tool, and calculating the gravity of the load tool according to the relational expression (III);
(d) and (3) constructing a relation (IV) between a rotation matrix from a robot base coordinate system to a tail end flange coordinate system, a zero value of six-dimensional sensor force, a zero value of moment and a mounting angle between the sensor coordinate system and the tail end flange coordinate system along the Z axis, and calculating the mounting angle by using the relation (IV).
Further preferably, in step (a), the relation (one) preferably adopts the following equation:
wherein, Fx、FyAnd FzForce readings, M, on the X, Y and Z axes of the sensor, respectivelyx、MyAnd MzAre the torque readings on the X, Y and Z axes, X, Y and Z are the coordinates of the center of gravity of the tool mass along the X, Y and Z axes, respectively, k1、k2And k3Is an intermediate parameter.
Further preferably, in step (a), the relation (ii) is preferably according to the following equation:
wherein, Fx0，Fy0And Fz0Zero values of the forces of the sensor on the X-axis, Y-axis and Z-axis, Mx0，My0And Mz0The zero values of the moments of the sensor on the X axis, the Y axis and the Z axis are respectively.
Further preferably, in step (c), the relation (iii) is preferably according to the following equation:
wherein g is the tool gravity.
Further preferably, in step (d), the relation (iv) is preferably performed according to the following steps:
wherein R isijIs the element in the ith row and the jth column of the rotation matrix, and theta is the installation angle of the sensor coordinate system and the end flange coordinate system along the Z axis.
Further preferably, in step (d), the calculation of the mounting angle using the relation (IV) is preferably performed by taking force readings F on the X-axis, Y-axis and Z-axis of the sensor at t different attitudesx、Fy、FzAnd joint angles of six joint axes of the robot, and then using the relationship of (four) to establish the following equation, thereby calculating the installation angle theta,
wherein the content of the first and second substances,tRijis the element in the ith row and jth column of the first calculation result in the t-th rotation matrix, FxtAnd FytIs the t-th sensor x-axis and y-axis force reading.
Further preferably, in step (d), the rotation matrix is calculated preferably using a positive kinetic equation.
In general, compared with the prior art, the above technical solution contemplated by the present invention can achieve the following beneficial effects:
1. according to the invention, readings of a plurality of groups of sensors and joint angles of the robot under different postures are measured, then a solving relation among the gravity of a load tool, the zero point of the sensor and the installation angle of the sensor is constructed, and the zero point is obtained by utilizing the relation and calculating, so that the calibration of the zero point of the six-dimensional sensor is realized, and the measurement precision is improved;
2. the method provided by the invention has the advantages that the calibration time of the six-dimensional force sensor at the tail end of the industrial robot is obviously shortened, the calibration result is accurate, the calibration result is utilized to compensate the reading of the sensor, and the reading accuracy of the sensor is obviously improved.
Drawings
FIG. 1 is a flow chart of a robot end six-dimensional force sensor calibration method constructed in accordance with a preferred embodiment of the present invention;
FIG. 2 is a schematic diagram of a robot end six-dimensional force sensor constructed in accordance with a preferred embodiment of the present invention;
fig. 3 is a force diagram of a robot end six-dimensional force sensor constructed in accordance with a preferred embodiment of the present invention after installation of a load tool.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further 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. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
Fig. 1 is a flow chart of a calibration method of a six-dimensional force sensor at the end of a robot constructed according to a preferred embodiment of the present invention, and as shown in the figure, the following steps specifically describe the derivation process of the method of the present invention:
the method comprises the following steps: controlling the robot to change different postures, recording readings of the six-dimensional force sensors under the different postures, and constructing an equation according to a stress analysis graph of tool gravity in a sensor coordinate system (in the graph, O represents an origin of the sensor coordinate system, and G represents the tool gravity) after the tail end six-dimensional force sensor is provided with a load tool as shown in FIG. 3:
wherein Fx、FyAnd FzRespectively representing force readings (unit: N), M on the X-axis, Y-axis, and Z-axis of the sensorx、MyAnd MzThe torque readings (in Nm) on the X-axis, Y-axis and Z-axis are shown, respectively. x, y and z represent the coordinates (in m) of the center of gravity of the tool mass.
Wherein Fx0、Fy0、Fz0Zero values of forces on the X-axis, Y-axis and Z-axis of the sensor, and unknown number M to be solvedx0、My0、Mz0The zero values of the moments on the X axis, the Y axis and the Z axis of the sensor are unknown numbers to be solved.
Step two: repeating the steps r times (r > is 3), and simultaneously establishing N equations to form an equation system:
i.e. M ═ F · P, where P ═ x yz1k 2k 3]Tk, solving the system of equations to obtain P ═ FTF)-1FTM, it should be noted that the selected pose must be different when repeating step one.
Step three: repeating the step two times s (s > -3), and simultaneously connecting s equations to form an equation system:
wherein xs、ys、zsRespectively representing the results of the second s-th calculation in the step1s、k2s、k3sRespectively representing the calculation results of the second M times in the step. Solve this equation F0＝(ATA)-1ATK, obtaining zero values F on six axes of the six-dimensional sensorx0，Fy0、Fz0、Mx0，My0And Mz0。
Step four: controlling the robot to change the posture, recording the readings of the sensor on six axes, Fx、Fy、Fz、Mx、MyAnd Mz. Calculating load tool gravity
Step five: controlling the robot to change different postures and recording force readings F on the X axis, the Y axis and the Z axis of the sensorx、FyAnd FzAnd the joint angle (unit: rad) Q of six joint axes of the robot is [ Q ]1 q2 q3 q4 q5 q6]And calculating a transformation matrix from the terminal flange coordinate system to the base coordinate system by using a positive kinematics equation of the robot:
wherein the content of the first and second substances,
for a rotation matrix, R, from the robot base coordinate system to the end flange coordinate systemijRepresenting the element of the rotation matrix at row i and column j. And selecting partial elements in the rotation matrix R to construct an equation:
where θ represents the mounting angle of the sensor coordinate system and the end flange coordinate system along the Z-axis.
Step six: repeating the step five times (t > -3), and simultaneously combining t equations to form an equation set:
i.e., R · x ═ F, where x ═ sin θ cos θ]TIn which F isxtAnd FytShowing the result of the fifth t-th measurement,tRijexpressing the result of the t-th calculation in step five, solving this equation set yields x ═ (R)TR)-1RTF＝[x1 x2]T. Sensor mounting angle θ ═ atan (x)2,x1)。
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (6)
1. A method for calibrating a six-dimensional force sensor at the end of an industrial robot is characterized by comprising the following steps:
(a) in the measuring process of the six-dimensional force sensor, a relational expression (I) about the force, the moment and the displacement measured on the sensor is constructed according to the force and the moment of the load tool measured by the sensor, and a relational expression (II) about the zero values of the force and the moment on the sensor and the mass center of the load tool is constructed according to the relational expression;
(b) acquiring data of force and moment measured by a six-dimensional force sensor under r multiplied by s postures, wherein each r data is a group of data, s groups of data are obtained, s displacements are calculated according to a relational expression (I) by utilizing the s groups of data, and the s displacements are combined with the relational expression (II) for calculation to obtain zero values of the force and the moment of the six-dimensional force sensor;
(c) constructing a relational expression (III) of the zero values of the force and the moment of the six-dimensional force sensor and the gravity of the load tool according to the relationship between the zero values and the gravity of the load tool, and calculating the gravity of the load tool according to the relational expression (III);
(d) constructing a relation (IV) between a rotation matrix from a robot base coordinate system to a tail end flange coordinate system, a zero value of six-dimensional force sensor force, a zero value of moment and a mounting angle between the sensor coordinate system and the tail end flange coordinate system along the Z axis, and calculating the mounting angle by using the relation (IV);
the relation (IV) is carried out according to the following steps:
wherein R isijIs the element in the ith row and the jth column of the rotation matrix, and theta is the installation angle of the sensor coordinate system and the end flange coordinate system along the Z axis.
2. A method for calibration of an industrial robot end six-dimensional force sensor according to claim 1, characterized in that in step (a), the relation (one) uses the following equation:
wherein, Fx、FyAnd FzForce readings, M, on the X, Y and Z axes of the sensor, respectivelyx、MyAnd MzAre the torque readings on the X, Y and Z axes, X, Y and Z are the coordinates of the center of gravity of the tool mass along the X, Y and Z axes, respectively, k1、k2And k3Is an intermediate parameter.
3. A method for calibration of an industrial robot end six-dimensional force sensor according to claim 1 or 2, characterized in that in step (a), the relation (ii) is according to the following equation:
wherein, Fx0，Fy0And Fz0Zero values of the forces of the sensor on the X-axis, Y-axis and Z-axis, Mx0，My0And Mz0The zero values of the moments of the sensor on the X axis, the Y axis and the Z axis are respectively.
4. A method for calibration of an industrial robot end six-dimensional force sensor according to claim 1, characterized in that in step (c), the relation (three) is according to the following equation:
wherein g is the tool gravity.
5. A method of calibration of an industrial robot end six-dimensional force sensor according to claim 1, characterized in that in step (d) the calculation of the setting angle using the relation (iv) is performed by taking force readings F on the X-, Y-, and Z-axes of the sensor at t different posesx、Fy、FzAnd joint angles of six joint axes of the robot, and then the following equation is established using the relation (IV) to calculate the installation angle theta,
wherein the content of the first and second substances,tRijis the element in the ith row and jth column of the first calculation result in the t-th rotation matrix, FxtAnd FytIs the t-th sensor x-axis and y-axis force reading.
6. The method for calibrating an industrial robot six-dimensional end force sensor of claim 1, wherein in step (d), the rotation matrix is obtained by calculation using a positive kinetic equation.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910213295.3A CN109822574B (en) | 2019-03-20 | 2019-03-20 | Industrial robot end six-dimensional force sensor calibration method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910213295.3A CN109822574B (en) | 2019-03-20 | 2019-03-20 | Industrial robot end six-dimensional force sensor calibration method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN109822574A CN109822574A (en) | 2019-05-31 |
| CN109822574B true CN109822574B (en) | 2021-01-05 |
Family
ID=66870905
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201910213295.3A Active CN109822574B (en) | 2019-03-20 | 2019-03-20 | Industrial robot end six-dimensional force sensor calibration method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN109822574B (en) |
Families Citing this family (18)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110103229B (en) * | 2019-06-06 | 2022-09-13 | 上海电气集团股份有限公司 | Gravity compensation method and system for tool arranged at tail end of robot |
| CN112611499B (en) * | 2019-09-18 | 2022-01-28 | 马洪文 | Method for measuring micro displacement of load platform of multi-dimensional force sensor and method for mounting measuring sensitive element |
| CN110802585B (en) * | 2019-11-20 | 2021-04-16 | 山东大学 | Mechanical arm tail end sensor compensation method and contact force/moment measurement method |
| DE102019134666B4 (en) * | 2019-12-17 | 2022-03-31 | Franka Emika Gmbh | Calibrating a virtual force sensor of a robotic manipulator |
| CN111189577B (en) * | 2020-01-16 | 2022-01-07 | 腾讯科技（深圳）有限公司 | Sensor calibration and data measurement method, device, equipment and storage medium |
| CN111230879B (en) * | 2020-02-20 | 2023-07-11 | 佛山科学技术学院 | Robot tail end contact force compensation method and system based on force sensor |
| CN111531533A (en) * | 2020-04-14 | 2020-08-14 | 佛山市南海区广工大数控装备协同创新研究院 | Zero point correction and gravity compensation method for six-dimensional force sensor |
| CN111590564A (en) * | 2020-05-07 | 2020-08-28 | 北京控制工程研究所 | Gravity compensation method and system for six-dimensional force sensor |
| CN113733079B (en) * | 2020-05-29 | 2022-12-20 | 配天机器人技术有限公司 | Robot installation angle checking method and device and computer storage medium |
| CN114074327A (en) * | 2020-08-20 | 2022-02-22 | 上海飞机制造有限公司 | Control method and device of auxiliary assembly robot and auxiliary assembly system |
| CN112518745B (en) * | 2020-11-25 | 2022-06-10 | 中科新松有限公司 | Robot TCP rapid calibration method |
| CN112710424B (en) * | 2020-12-08 | 2021-08-24 | 上海交通大学 | Method for calibrating six-dimensional force sensor at tail end of robot |
| CN113510698B (en) * | 2021-04-26 | 2022-07-29 | 深圳市优必选科技股份有限公司 | Mechanical arm control method and device, mechanical arm and readable storage medium |
| CN113568369B (en) * | 2021-07-16 | 2022-09-30 | 英诺威讯智能科技（杭州）有限公司 | Method for measuring relative precision of built-in system for zero calibration of full-automatic robot |
| CN113664813B (en) * | 2021-08-25 | 2022-07-29 | 深圳市优必选科技股份有限公司 | Method and device for controlling double-arm robot, double-arm robot and readable storage medium |
| CN113771044B (en) * | 2021-10-09 | 2022-11-11 | 北京卫星环境工程研究所 | Robot tail end load dynamic stress sensing method |
| CN114310916B (en) * | 2022-02-25 | 2024-02-06 | 哈尔滨工业大学 | Identification method and identification system for contact force during interaction of robot and environment |
| CN117387834B (en) * | 2023-12-04 | 2024-02-23 | 杭州灵西机器人智能科技有限公司 | Force sensor calibration method, system, electronic equipment and storage medium |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP5028751B2 (en) * | 2005-06-09 | 2012-09-19 | ソニー株式会社 | Action recognition device |
| JP5459486B2 (en) * | 2010-01-26 | 2014-04-02 | 株式会社Ｉｈｉ | Robot calibration method and apparatus |
| CN102353482B (en) * | 2011-07-07 | 2013-01-30 | 北京航空航天大学 | Torque sensor capable of measuring six-dimensional non-coplanar force |
| CN106994687B (en) * | 2017-03-30 | 2019-08-20 | 北京卫星环境工程研究所 | Industrial robot end six-dimension force sensor Installation posture scaling method |
| CN107105147B (en) * | 2017-06-05 | 2019-06-21 | 北京理工大学 | A kind of bionical super-resolution imaging sensor and imaging method |
| CN110315396B (en) * | 2018-03-29 | 2020-09-08 | 华中科技大学 | Industrial robot constant-force grinding and polishing method based on big data |
| CN109124769B (en) * | 2018-09-10 | 2021-06-04 | 上海电气集团股份有限公司 | Method and system for calibrating and controlling coordinate system of surgical robot |
-
2019
- 2019-03-20 CN CN201910213295.3A patent/CN109822574B/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| CN109822574A (en) | 2019-05-31 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN109822574B (en) | Industrial robot end six-dimensional force sensor calibration method | |
| CN110161850B (en) | Variable parameter rigidity identification and modeling method for industrial robot | |
| CN107042528B (en) | A kind of Kinematic Calibration system and method for industrial robot | |
| WO2021238617A1 (en) | Industrial robot absolute precision calibration system and method | |
| CN110193829B (en) | Robot precision control method for coupling kinematics and rigidity parameter identification | |
| Yu et al. | Simultaneous and on-line calibration of a robot-based inspecting system | |
| CN107703748B (en) | Heavy-load robot static stiffness identification method based on offset plate design | |
| CN106595474A (en) | Double-robot base coordinate system calibration method based on laser tracker | |
| CN109238199B (en) | Robot rotating shaft kinematic parameter calibration method | |
| CN110715769A (en) | Method for calibrating stress point position of weighing sensor of multi-point method centroid measuring equipment | |
| WO2021128761A1 (en) | Distributed multi-dimensional force measurement system and measurement method | |
| JP2012040634A (en) | Calibration device and method for power-controlled robot | |
| CN110871434B (en) | Kinematics calibration method of parallel processing equipment | |
| CN112847341A (en) | Industrial robot step-by-step calibration system and method | |
| CN112767493B (en) | Machine vision calibration method for kinematic parameters of Stewart platform | |
| CN112659112A (en) | Robot eye calibration method based on line laser scanner | |
| CN111452048A (en) | Calibration method and device for relative spatial position relationship of multiple robots | |
| CN109443273B (en) | Method for accurately positioning workpiece to be measured by using three-dimensional measurement system | |
| CN114216456A (en) | Attitude measurement method based on IMU and robot body parameter fusion | |
| CN112304218A (en) | Tool center point position calibration method and system of industrial robot | |
| Peng et al. | Development of an integrated laser sensors based measurement system for large-scale components automated assembly application | |
| CN113319855B (en) | Gravity compensation method under compliance control mode of multi-joint diagnosis and treatment robot | |
| CN113513999B (en) | Large-view-field real-time deformation measurement system and method for static test of spacecraft structure | |
| CN113878586B (en) | Robot kinematics calibration device, method and system | |
| CN116652953A (en) | Error compensation and processing method for dynamic contact force measurement of robot tail end model |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |