CN115307816A - Calibration test system and calibration method for harmonic flexible gear torque sensor - Google Patents
Calibration test system and calibration method for harmonic flexible gear torque sensor Download PDFInfo
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- CN115307816A CN115307816A CN202211017694.0A CN202211017694A CN115307816A CN 115307816 A CN115307816 A CN 115307816A CN 202211017694 A CN202211017694 A CN 202211017694A CN 115307816 A CN115307816 A CN 115307816A
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- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L25/00—Testing or calibrating of apparatus for measuring force, torque, work, mechanical power, or mechanical efficiency
- G01L25/003—Testing or calibrating of apparatus for measuring force, torque, work, mechanical power, or mechanical efficiency for measuring torque
Abstract
The invention discloses a calibration test system and a calibration method of a harmonic flexible gear torque sensor. The calibration test system can be combined and matched according to the requirements of a calibration application scene and comprises a movable base module, a guide rail sliding block module, a fixed base module, a sliding base module, a hysteresis moment loader module, a standard torque sensor module, a harmonic flexible gear torque sensor module to be calibrated, a weight loading arm module, a motor module and a brake braking module; the calibration method disclosed by the invention is a complete set of static calibration and dynamic verification process of the harmonic flexible gear torque sensor. The static calibration and dynamic verification of the harmonic flexible wheel torque sensor can be performed through the calibration system. The method is simple and convenient to operate, the acquisition and processing of the calibration data can be automatically completed, the influence of human factors is reduced, the accuracy of the calibration result is improved, the torque calibration is simple and easy to implement, the calibration cost is reduced, and the calibration efficiency and precision are improved.
Description
Technical Field
The invention relates to the technical field of measurement of robot sensors, in particular to a calibration test system and a calibration method for a harmonic flexible gear torque sensor.
Background
With the development of cooperative robot technology and the improvement of human-computer interaction performance requirements, a cooperative robot generally needs to have a force control function. There are generally three ways to solve force control:
one is to use the current feedback of the motor to estimate the torque, which is a way that has large error, complex calculation and low cost, and is basically used by early cooperative robots.
The second way is to add a multidimensional force/torque sensor at the tail end of the robot, and the force or torque applied to the tail end joint can be converted into joint space through a series of mathematical calculations to carry out joint force control. This approach is currently being adopted by most cooperating robot manufacturers. However, this method has problems of high cost and complicated calculation, and cannot calculate joint torque if external force is not applied to the distal joint, and therefore cannot be used in cases where safety requirements are high, such as collision detection.
The third mode is to add an independent torque sensor to each joint for joint force control. The method can directly avoid the difficult problems of complex dynamics calculation and parameter identification, and also avoids the problems of noise interference, time delay and the like introduced in the dynamics equation. However, the problem of this method is that an independent torque sensor is installed in each joint, so that an extra flexible unit is added, the volume is increased, the overall rigidity and transmission precision of the joint are obviously reduced, and the cost is increased.
At present, a method for solving the above problems in the industry is to use the elasticity of the flexible gear of the harmonic reducer to manufacture an embedded harmonic flexible gear torque sensor, so that the harmonic reducer has a torque sensing function. Due to the complexity of a flexible deformation mechanism of the flexible gear, at present, no unified standard and method is formed for the calibration of the harmonic flexible gear torque sensor with the torque sensing function, the designed calibration test board mostly borrows the calibration mode of the traditional torque calibration test board, the pertinence and the uniqueness are lacked, the calibration operation is too complex, the calibration precision is not high, and the flexible gear torque sensor is not suitable for being widely used.
In addition, the conventional strain gauge type torque sensor is calibrated only by considering the deformation of a strain beam of the conventional strain gauge type torque sensor and not by considering the influence of the periodic deformation of the harmonic flexible gear, and the conventional strain gauge type torque sensor only needs to calibrate a moment-voltage one-time function relation line.
Disclosure of Invention
Aiming at the defects of the prior art and the actual requirement of precision calibration of the embedded harmonic flexible gear torque sensor of the cooperative robot, the invention provides a calibration test system and a calibration method of the harmonic flexible gear torque sensor for the integrated joint module of the cooperative robot. The harmonic flexible gear torque sensor has the characteristics of simple and portable structure, modular assembly of all units, simplicity and convenience in debugging, and capability of being assembled with various types of harmonic flexible gear torque sensors and external members thereof so as to realize multi-scene combined application. In addition, the matched calibration test software and calibration method can realize the visual and automatic operation of the calibration process and result, and complete the calibration work of the harmonic flexible gear torque sensor in a low-cost, high-efficiency and high-requirement mode.
In order to achieve the above purpose, the invention firstly provides a calibration test system of a harmonic flexible gear torque sensor, which comprises a movable base module, a guide rail slider module, a fixed base module, a sliding base module, a hysteresis moment loader module, a standard torque sensor module, a harmonic flexible gear torque sensor module to be calibrated, a weight loading arm module, a motor module, a brake module and an upper computer;
the guide rail sliding block module comprises a wide guide rail and a plurality of movable sliding blocks; the wide-width guide rail is fixed on the upper surface of the movable base module along the length direction of the movable base module, and the movable sliding blocks are all arranged on the wide-width guide rail and can slide along the wide-width guide rail;
the bottom of the fixed seat module is provided with a positioning groove, the width of the positioning groove is equal to that of the wide guide rail, the inner wall surface of the positioning groove is tightly attached to two outer side surfaces of the wide guide rail, the positioning groove is tightly attached to the upper surface of the movable base module, and the whole fixed seat module is fixedly arranged on the movable base module;
the sliding seat modules are as many as the movable sliding blocks and are respectively arranged on the corresponding movable sliding blocks, and the sliding seat modules can be fixed on the movable base modules through the detachable fixing pieces; when the fixing piece is disconnected with the sliding seat module, the sliding seat module can slide along the wide guide rail;
the hysteresis moment loader module is arranged on a sliding seat module and is used for carrying out dynamic calibration and testing a static calibration result, namely the accuracy of the static calibration result is verified through dynamic loading moment; the standard torque sensor module and the harmonic flexible gear torque sensor module to be calibrated are respectively arranged on different sliding seat modules; one end of the standard torque sensor module is connected with the flexible gear torque sensor module to be calibrated through a diaphragm coupler; when the dynamic verification calibration is carried out, the hysteresis moment loader module is connected with the other end of the standard torque sensor module through a diaphragm coupler; when static calibration is carried out, the other end of the standard torque sensor module is fixedly connected with the weight loading arm module; the weight loading arm module is used for applying torque during static calibration; (ii) a
The module of the harmonic flexible gear torque sensor to be calibrated is a harmonic reducer containing the harmonic flexible gear torque sensor to be calibrated or a joint module comprising the harmonic reducer, an absolute position encoder, a brake and a torque motor;
when the harmonic flexible gear torque sensor module to be calibrated is used for testing the joint module, the testing system is not provided with a motor module and a brake module;
when the harmonic flexible gear torque sensor module to be calibrated is in a harmonic reducer form, the motor module is fixed on a sliding seat module, and the brake module is installed on the motor module for carrying out band-type brake on the output of the motor or installed on the harmonic flexible gear torque sensor module to be calibrated for carrying out band-type brake on the input end;
the upper computer is respectively connected with the hysteresis torque loader module, the standard torque sensor module and the harmonic flexible gear torque sensor module to be calibrated, controls the hysteresis torque loader to load different torques, and obtains the torque of the standard torque sensor module and the output voltage value of the harmonic flexible gear torque sensor module to be calibrated.
On the other hand, the invention also provides a calibration method of the calibration test system, the calibration method comprises static calibration and dynamic calibration verification, and the method specifically comprises the following steps:
step 1: installing a joint module or a speed reducer containing a harmonic flexible gear torque sensor to be detected on a calibration rack, and enabling an output shaft of the joint module or the speed reducer to be coaxially connected with an input shaft at one end of a standard torque sensor through a diaphragm coupler, wherein an output shaft at the other end of the standard torque sensor is fixedly connected with a weight loading arm, and the weight loading arm is kept relatively horizontal; the joint module or the output shaft of the speed reducer is locked through the brake of the band-type brake, and the position reading fed back by the encoder of the output shaft of the joint module or the speed reducer is set to be a zero position;
step 2: loading a weight to one end of a weight loading arm; at this time, the torque T exerted by the weight is calculated by the effective arm length of the loading arm and the weight of the weight to be loaded fa The standard torque sensor itself accurately measures the torque T applied at that time st And transmitted to an upper computer through a communication interface, and compared by T fa And T st If the difference is within the error range, T st The value is available, and the calibration can be continued; otherwise, checking whether the standard torque sensor instrument is damaged or not, checking whether the weight calculation of the added weight is correct or not, and checking whether the installation of the long arm rod is correct or not;
and step 3: repeating the step 2, setting the interval of the calibration points according to the rated output torque of the harmonic reducer, ensuring that the number of the calibration points is not less than 10, then loading weights step by step according to the torque value set by the calibration points until the reading of the standard torque sensor is stable, and finishing one-time loading; each time a corresponding torque value T is loaded st All can be transmitted to an upper computer in real time for processing, and simultaneously, the output collected from a flexible gear torque sensor to be calibratedThe voltage signal can be transmitted to the upper computer in real time; torque value T of weight gravity in loading process sti And the output voltage value U of the harmonic flexible gear torque sensor to be calibrated i The mathematical model in between is: t is sti ＝k 0i +k 1i U i (ii) a Subscript i denotes the ith load;
and 4, step 4: after the loading calibration of all calibration points is finished, establishing a calibration model on the upper computer by adopting a least square method according to the mathematical model in the step 3, realizing the calibration of the harmonic flexible gear torque sensor to be calibrated, and obtaining a loading calibration coefficient k of the sensor 0i ，k 1i Completing one-time loading calibration;
and 5: step-by-step unloading the loaded weights according to the number of the calibration points determined in the step (3) in the opposite direction, uploading the torque value of the standard torque sensor and the output voltage value of the harmonic flexible wheel torque sensor to be calibrated to an upper calibration program after the system is stabilized, and realizing unloading calibration to obtain a primary unloading calibration coefficient;
and 6: repeating the steps to finish at least 5 times of loading calibration and at least 5 times of unloading calibration, averaging the obtained calibration coefficients and taking the average as a fitting straight line calibration coefficient k at the position, namely the zero position 0 ，k 1 ；
And 7: due to the calibration coefficient k 0 Is changed in a sine wave mode along with the change of the position of the wave generator of the harmonic reducer, so that the proper k is fitted 0 A sine curve graph, which evenly subdivides the calibration positions according to the circumferential direction and sets the angle between two adjacent calibration positions as alpha; after completing the calibration of one position, controlling the motor to rotate by alpha degrees, and then repeating the steps 2-6 to obtain a group of calibration coefficients k of a new calibration position 0 ，k 1 ；
And step 8: repeating the step 7 until the calibration of all the calibration positions is completed; wherein, as with zero calibration, each calibration position completes at least 5 times of loading calibration and at least 5 times of unloading calibration, and the obtained calibration coefficients are averaged; fitting a smooth sinusoidal curve to the mean value at each position, where each position corresponds to a unique set of torque coefficients k 0 ，k 1 And correspond to the absolute position encoder position one by one;
and step 9: unloading the weight loading arm module from the loading end of the standard torque sensor, and coaxially connecting the hysteresis moment loader module with the standard torque sensor module by using a diaphragm coupling;
step 10: reading in a calibration coefficient of static calibration and a related sinusoidal coefficient obtained by fitting; and controlling the hysteresis moment loader to load different moments as the load moment of the joint module to be tested, and dynamically verifying and calibrating whether the harmonic flexible gear torque sensor to be tested is in an error range by comparing the moment loaded by the hysteresis moment loader, the moment measured by the standard torque sensor and the moment measured by the harmonic flexible gear torque sensor.
The invention has the advantages and positive effects that:
the conventional strain gauge type torque sensor is calibrated only by considering the deformation of a strain beam of the conventional strain gauge type torque sensor and does not consider the influence of periodic deformation of a harmonic flexible gear. The harmonic flexible gear torque sensor of the invention can cause the flexible gear to generate periodic deformation due to the periodic motion of the wave generator, so the invention also carries out static calibration at different positions of the periodic deformation of the flexible gear during the static calibration and fits a smooth periodic sine curve, each point of the sine curve represents a flexible gear position, and each position is provided with a unique corresponding calibrated moment-voltage linear function relation line. The conventional strain gauge type torque sensor only needs to calibrate a moment-voltage linear function relation line, but the invention also needs to calibrate a sine curve corresponding to the periodic deformation position of the flexible gear besides the moment-voltage linear function relation line.
The method is suitable for calibrating the harmonic flexible gear torque sensor only with a reducer module and also suitable for calibrating the harmonic flexible gear torque sensor in the integrated joint module of the cooperative robot; because the positions of the hysteresis torque loader module, the standard torque sensor module and the harmonic flexible gear torque sensor module to be calibrated can be adjusted along the slide rail and then fixed, the harmonic flexible gear torque sensors in various types and external members thereof can be assembled to realize multi-scene combined application.
The invention adopts the base aluminum profile and the lifting type Frounet wheel, realizes the lightness of the structure, reduces the processing and manufacturing cost and can move to any suitable test occasion under the condition of ensuring high bearing capacity.
The guide rail sliding block part of the invention adopts a single wide guide rail, compared with the conventional double-guide-rail combination, the wide single-guide rail avoids high matching requirement and complicated manual debugging brought by double-guide-rail installation under the condition of ensuring good anti-overturning capability.
Each module designed by the invention can be easily detached and replaced, so that the calibration of the torque sensor has higher freedom; technical staff can adopt two sets of or multiunit sliding seat module to realize the fixed mounting of different test pieces according to the test demand of difference, also can use two sets of or multiunit multi-functional test platform cooperation, has realized multi-scene combination and has used, not only satisfies the demand of different functional test in actual measurement is used, and the installation is simple and easy moreover, very big shortening engineering test cycle, practiced thrift the cost. The invention is suitable for static calibration and dynamic verification of harmonic reducers with different rated loads, namely harmonic flexible gear torque sensors with different measuring ranges.
In addition, the invention can realize static calibration and dynamic calibration verification at one time, the torque sensor calibration method provided by the invention is simple and convenient to operate, the collection and processing of calibration data can be automatically completed by matching with the provided upper computer calibration program, the influence of human factors is reduced, the accuracy of the calibration result is improved, the torque calibration is simple and easy to implement, the calibration cost is reduced, and the calibration efficiency and precision are improved.
Drawings
FIG. 1 is a schematic structural diagram of a calibration system for a harmonic flexspline torque sensor of a joint module according to an embodiment of the present invention;
FIG. 2 is a front view of FIG. 1;
FIG. 3 is a schematic diagram of the calibration of a harmonic flexspline torque sensor of a pure speed reducer module according to embodiment 1 of the present invention;
FIG. 4 is a side view of FIG. 3;
fig. 5 is a schematic diagram illustrating calibration of a harmonic flexspline torque sensor of the integrated joint module according to embodiment 2 of the present invention;
FIG. 6 is a top view of FIG. 5;
fig. 7 is a schematic diagram of dynamic calibration and verification of a joint module to be tested in embodiment 2 of the present invention;
FIG. 8 is a flow chart of a calibration scheme provided by an embodiment of the present invention;
FIG. 9 is a cut-away schematic view of a bracket with a bearing;
FIG. 10 is a schematic view of a long arm with a keyway mounting hole for a mounting surface to be flanged.
In the figure, a movable base module 1, a guide rail slider module 2, a fixed base module 3, a sliding base module 4, a hysteresis torque loader module 5, a standard torque sensor module 6, a harmonic flexible gear torque sensor module 7 to be calibrated, a weight loading arm module 8, a brake module 9, a Frouhorse wheel 10, an aluminum profile seat frame 11, an installation bottom plate 12, a wide guide rail 13, a movable slider 14, a movable slider 15, a hysteresis torque loader 16, a hysteresis torque loader installation frame 17, a high-precision torque sensor 18, a high-precision torque sensor installation frame 19, harmonic flexible gear torque sensors 20 and 21 to be tested, harmonic flexible gear torque sensor installation frames 22 and 23 to be tested, a support 24 with a bearing, a long arm 25 with a flange installation surface to be tested, a weight 26, a direct current brushless servo motor 27, a motor installation frame 28, a brake 29, a diaphragm coupling 30 and a retention piece 31;24-1 is a support plate, 24-2 is a bearing, 24-3 is a bearing pressure plate, 24-4 shaft sleeves, 24-5 is a set screw, and 24-6 is a key on a standard torque sensor.
Detailed Description
The invention will be further illustrated and described with reference to specific embodiments. The described embodiments are merely exemplary of the disclosure and are not intended to limit the scope thereof. The technical features of the embodiments of the present invention can be combined correspondingly without mutual conflict.
As shown in fig. 1-7, the calibration rack comprises a movable base module 1, a guide rail slider module 2, a fixed base module 3, a sliding base module 4, a hysteresis moment loader module 5, a standard torque sensor module 6, a harmonic flexible gear torque sensor module 7 to be calibrated, a weight loading arm module 8, a motor module, a brake module 9 and an upper computer; the upper computer is respectively connected with the hysteresis torque loader module 5, the standard torque sensor module 6 and the harmonic flexible gear torque sensor module 7 to be calibrated, controls the hysteresis torque loader to load different torques, and obtains the torque of the standard torque sensor module 6 and the output voltage value of the harmonic flexible gear torque sensor module to be calibrated. In the embodiment of the invention, the automation of the calibration process is realized by setting a static calibration program and a dynamic verification program on the upper computer.
The movable base module comprises a liftable Foumau wheel 10, an aluminum profile seat frame 11 and a mounting bottom plate 12, wherein the mounting bottom plate is mounted on the aluminum profile seat frame, and a guide rail sliding block module, a fixed seat module and a movable retention piece 31 are mounted above the mounting bottom plate. The Frouhorse wheel is arranged at the bottom of the seat frame. The horsewheel is fixed by a liftable connecting piece to realize a lifting function, and the liftable connecting piece can be lifted by a thread structure through rotation.
The guide rail sliding block module comprises a wide guide rail 13 and a plurality of movable sliding blocks 14; the wide guide rail is fixed on the upper surface of the movable base module along the length direction of the movable base module, and the movable sliding blocks are all arranged on the wide guide rail and can slide along the wide guide rail;
the bottom of the fixed seat module 3 is provided with a positioning groove, the width of the positioning groove is equal to the width of the wide guide rail 13, the inner wall surface of the positioning groove is tightly attached to two outer side surfaces of the wide guide rail 13, the positioning groove is tightly attached to the upper surface of the movable base module 1, and the whole fixed seat module 3 is fixedly arranged on the movable base module 1;
the sliding seat modules 4 are respectively arranged on the 4 movable sliding blocks 15, and two sides of the sliding seat modules are fixed on the movable base module through detachable fixing pieces 31; when the fixing piece 31 is disconnected from the sliding seat module 4, the sliding seat module 4 can slide along the wide guide rail 13; the number of the sliding seat modules is determined according to the calibration requirement, and is generally not less than 2.
The hysteresis torque loader module according to the embodiment comprises a hysteresis torque loader 16, a hysteresis torque loader mounting frame 17 and an associated hysteresis torque controller. The hysteresis moment loader is fixedly connected to a sliding seat module through a mounting frame of the hysteresis moment loader. The hysteresis torque controller can control the output torque of 1-30 nm as required. The purpose of the hysteresis moment loader module is mainly to perform dynamic calibration and test the static calibration result. The accuracy of the static calibration result can be fully verified through the dynamic loading torque.
The standard torque sensor module of the embodiment comprises a high-precision torque sensor 18, a high-precision torque sensor mounting frame 19 and a related torque acquisition display instrument. The standard torque sensor is fixedly connected to a sliding seat module through a mounting frame of the standard torque sensor. The precision grade of the standard torque sensor is higher than that of the harmonic flexible gear torque sensor to be calibrated by 1-2 orders of magnitude, and the torque value of the standard torque sensor can be uploaded to an upper computer for relevant processing in real time through a collecting instrument.
The harmonic flexible gear torque sensor module to be calibrated comprises harmonic flexible gear torque sensors 20 and 21 to be calibrated and mounting frames 22 and 23 of the harmonic flexible gear torque sensors. The harmonic flexible gear torque sensor to be measured is fixedly connected to one fixed seat module through the mounting frame. The harmonic flexspline torque sensor to be measured as an embodiment may take two forms, one is a single reducer form 20, and the other is an integrated joint module form 21 containing an absolute position encoder, a brake and a torque motor. In the embodiment of the joint module type, a motor module and a brake module, which will be described later, may be omitted.
As shown in fig. 9 and 10, the weight-loading arm module according to the embodiment includes a bracket 24 with a bearing, a long arm 25 with a mounting surface to be flanged, and a plurality of loading weights 26. The support 24 with the bearing comprises a support plate 24-1, a bearing 24-2, a bearing pressing plate 24-3, a shaft sleeve 24-4 and a set screw 24-5; the bearing pressing plate 24-3 fixedly arranges the outer ring of the bearing 24-2 in the support plate 24-1, and the shaft sleeve 24-4 is fixed with the inner ring of the bearing 24-2; the support plate 24-1 is fixed on the upper surface of the movable base module 1; the key slot mounting hole is formed in one end of the long arm 25, and the long arm 25 is connected with the output shaft of the standard torque sensor 18 through a key 24-6, a shaft sleeve 24-4 and a set screw lock 24-5; a loading weight 26 is provided at the other end of the long arm 25.
The motor module of the illustrated embodiment includes a dc brushless servo motor 27 including an absolute position encoder output, a motor driver, and a motor mount 28. The motor is fixedly connected to one sliding seat module through a mounting frame of the motor.
The brake braking module comprises an electrified brake 29, which can be arranged on the motor module according to the calibration requirement to brake the motor output, or can be arranged on the harmonic flexible wheel torque sensor module to be calibrated to brake the input.
When the dynamic verification calibration is carried out, the hysteresis moment loader module is connected with one end of the standard torque sensor module through a diaphragm coupler; and when static calibration is carried out, one end of the output shaft at the other end of the standard torque sensor module is fixedly connected with the weight loading arm module. The standard torque sensor module and the harmonic flexible gear torque sensor module to be calibrated are connected through a diaphragm coupling. Before the diaphragm coupling is installed, the left position and the right position of the modules are adjusted through the coaxial correction device to enable the two shafts to be coaxial.
As shown in fig. 7 and 8, the present invention further provides a calibration method for a harmonic flexible gear torque sensor, taking a module 7 of the harmonic flexible gear torque sensor to be calibrated as an example of a joint module including a harmonic reducer, an absolute position encoder, a brake and a torque motor, and the present invention further provides a calibration method for a harmonic flexible gear torque sensor, the method includes static calibration and dynamic calibration verification, wherein the static torque calibration step of the joint module including the harmonic flexible gear torque sensor to be calibrated is as follows:
step 1: installing a joint module or a speed reducer containing a harmonic flexible gear torque sensor to be detected on a calibration rack, and enabling an output shaft of the joint module or the speed reducer to be coaxially connected with an input shaft at one end of a standard torque sensor through a diaphragm coupler, wherein an output shaft at the other end of the standard torque sensor is fixedly connected with a weight loading arm, and the weight loading arm is kept relatively horizontal; the joint module or the output shaft of the speed reducer is locked through the brake of the band-type brake, and the position reading fed back by the encoder of the output shaft of the joint module or the speed reducer is set to be a zero position;
step 2: loading a weight to one end of a weight loading arm; at this time, the torque T exerted by the weight is calculated by the effective arm length of the loading arm and the weight of the weight to be loaded fa The standard torque sensor itself accurately measures the torque T applied at that time st And transmitted to an upper computer through a communication interface, and compared by T fa And T st If the difference is within the error range, T st The value is available, and the calibration can be continued; otherwise, checking whether the standard torque sensor instrument is damaged, checking whether the weight calculation of the added weight is correct, and checking whether the installation of the long arm rod is correct; if none of the three check results is wrong, the difference between Tfa and Tst is within the error range, and the calibration can be continued.
And 3, step 3: repeating the step 2, setting the interval of the calibration points according to the rated output torque of the harmonic reducer, ensuring that the number of the calibration points is not less than 10, then loading weights step by step according to the torque value set by the calibration points until the reading of the standard torque sensor is stable, and finishing one-time loading; each time a corresponding torque value T is loaded st The harmonic flexible gear torque sensor to be calibrated is transmitted to an upper computer in real time for processing, and meanwhile, an output voltage signal acquired from the harmonic flexible gear torque sensor to be calibrated is also transmitted to the upper computer in real time; torque value T of weight gravity during loading sti And the output voltage value U of the harmonic flexible gear torque sensor to be calibrated i The mathematical model between is: t is sti ＝k 0i +k 1i U i (ii) a Subscript i denotes the ith load;
and 4, step 4: after the loading calibration of all calibration points is finished, a calibration model is established on the upper computer by adopting a least square method according to the mathematical model in the step 3, the calibration of the harmonic flexible gear torque sensor to be calibrated is realized, and a loading calibration coefficient k of the sensor is obtained 0i ，k 1i Completing one-time loading calibration;
and 5: step-by-step unloading the loaded weights according to the number of the calibration points determined in the step 3 in the opposite direction, uploading the torque value of the standard torque sensor and the output voltage value of the harmonic flexible wheel torque sensor to be calibrated to an upper calibration program after the system is stabilized, and realizing unloading calibration to obtain a primary unloading calibration coefficient;
and 6: repeating the steps to finish at least 5 times of loading calibration and at least 5 times of unloading calibration, averaging the obtained calibration coefficients and taking the averaged calibration coefficients as the calibration coefficients k of the fitting straight line at the position, namely the zero position 0 ，k 1 ；
And 7: due to the calibration coefficient k 0 Is changed in a sine wave mode along with the change of the position of the wave generator of the harmonic reducer, so that the proper k is fitted 0 The sine curve graph divides the calibration positions evenly in the circumferential direction, and in the embodiment, the calibration is carried out for 24 positions in a circle at intervals of 15 degrees. After completing the calibration of one position, controlling the motor to rotate for 15 degrees, and then repeating the steps 2-6 to obtain a group of calibration coefficients k of a new calibration position 0 ，k 1 ；
And step 8: repeating the step 7 until the calibration of all the calibration positions is completed; wherein, as with zero calibration, each calibration position completes at least 5 times of loading calibration and at least 5 times of unloading calibration, and the obtained calibration coefficients are averaged; fitting a smooth sinusoidal curve to the mean value at each position, where each position corresponds to a unique set of torque coefficients k 0 ，k 1 And corresponds one-to-one to the absolute position encoder position.
The dynamic calibration verification method provided by the invention comprises the following steps:
step 1: unloading the weight loading arm module from the loading end of the standard torque sensor, and coaxially connecting the hysteresis moment loader module with the standard torque sensor module by using a diaphragm coupling;
and 2, step: reading in a calibration coefficient of static calibration and a related sinusoidal coefficient obtained by fitting; and controlling the hysteresis moment loader to load different moments as the load moment of the joint module to be tested, and dynamically verifying and calibrating whether the harmonic flexible gear torque sensor to be tested is within an error range by comparing the moment loaded by the hysteresis moment loader, the moment measured by the standard torque sensor and the moment measured by the harmonic flexible gear torque sensor.
It should be noted that the expression method of the present invention is also applicable to the calibration of a harmonic flexible gear torque sensor with only a reducer module. In this way, the independent motor module and the brake module can replace a motor, an absolute position sensor and a band-type brake system in the joint module calibration mode to participate in the calibration process. The calibration step is consistent with the calibration step in the joint module mode, and the difference is that before calibration, an independent motor module, a brake module and a harmonic flexible wheel sensor to be tested are coaxially installed and connected, and the installation modes of other modules are kept unchanged.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit of the invention, and these are within the scope of the invention.
Claims (9)
1. A calibration test system of a harmonic flexible gear torque sensor is characterized by comprising a movable base module (1), a guide rail sliding block module (2), a fixed base module (3), a sliding base module (4), a hysteresis moment loader module (5), a standard torque sensor module (6), a harmonic flexible gear torque sensor module to be calibrated (7), a weight loading arm module (8), a motor module, a brake braking module (9) and an upper computer;
the guide rail sliding block module comprises a wide guide rail (13) and a plurality of movable sliding blocks (14); the wide-width guide rail is fixed on the upper surface of the movable base module along the length direction of the movable base module, and the movable sliding blocks are all arranged on the wide-width guide rail and can slide along the wide-width guide rail;
the bottom of the fixed seat module (3) is provided with a positioning groove, the width of the positioning groove is equal to that of the wide guide rail (13), the inner wall surface of the positioning groove is clung to two outer side surfaces of the wide guide rail (13), the positioning groove is clung to the upper surface of the movable base module (1), and the whole fixed seat module (3) is fixedly arranged on the movable base module (1);
the number of the sliding seat modules (4) is the same as that of the movable sliding blocks (14), the sliding seat modules are respectively arranged on the corresponding movable sliding blocks (14), and the sliding seat modules (4) can be fixed on the movable base modules through detachable fixing pieces (31); when the retention piece (31) is disconnected with the sliding seat module (4), the sliding seat module (4) can slide along the wide guide rail (13);
the hysteresis moment loader module is arranged on a sliding seat module (4) and is used for carrying out dynamic calibration and testing a static calibration result, namely verifying the accuracy of the static calibration result through dynamic loading moment; the standard torque sensor module and the flexible gear torque sensor module (7) to be calibrated are respectively arranged on different sliding seat modules (4); one end of the standard torque sensor module is connected with the flexible gear torque sensor module to be calibrated through a diaphragm coupler; when the dynamic verification calibration is carried out, the hysteresis moment loader module is connected with the other end of the standard torque sensor module through a diaphragm coupler; when static calibration is carried out, the other end of the standard torque sensor module is fixedly connected with the weight loading arm module; the weight loading arm module is used for applying torque during static calibration; (ii) a
The harmonic flexible gear torque sensor module (7) to be calibrated is a harmonic reducer containing a harmonic flexible gear torque sensor to be calibrated or a joint module comprising the harmonic reducer, an absolute position encoder, a brake and a torque motor;
when the harmonic flexible gear torque sensor module (7) to be calibrated is used for testing the joint module, the testing system is not provided with a motor module and a brake module (9);
when the harmonic flexible gear torque sensor module (7) to be calibrated is in a harmonic reducer form, the motor module is fixed on a sliding seat module, and the brake module (9) is arranged on the motor module to brake the motor output or arranged on the harmonic flexible gear torque sensor module to be calibrated to brake the input end;
the upper computer is respectively connected with the hysteresis torque loader module (5), the standard torque sensor module (6) and the harmonic flexible gear torque sensor module to be calibrated (7), controls the hysteresis torque loader to load different torques, and obtains the torque of the standard torque sensor module (6) and the output voltage value of the harmonic flexible gear torque sensor module to be calibrated.
2. The calibration test system of the harmonic flexible gear torque sensor according to claim 1, wherein the movable base module (1) comprises a liftable formalin wheel (10), an aluminum profile seat frame (11) and a mounting bottom plate (12), wherein the mounting bottom plate (12) is horizontally arranged on the aluminum profile seat frame as an upper surface for mounting the guide rail sliding block module, the fixed seat module and the movable retention piece (31); the Frouhorse wheel is arranged at the bottom of the aluminum profile seat frame; the horseback wheels are fixed by a liftable connecting piece to realize the lifting function.
3. The system of claim 2, wherein the lifting connection member is configured to be rotated to lift and lower by a screw structure.
4. The system for calibrating and testing the harmonic flexspline torque sensor according to claim 1, wherein the standard torque sensor has a precision level 1-2 orders of magnitude higher than that of the harmonic flexspline torque sensor to be calibrated.
5. The calibration test system of the harmonic flexible gear torque sensor according to claim 1, wherein the hysteresis torque loader module comprises a hysteresis torque loader (16), a hysteresis torque loader mounting frame (17) and a hysteresis torque controller; the hysteresis moment loader is fixedly connected to one sliding seat module through a hysteresis moment loader mounting frame; the hysteresis torque controller can control the output torque of 1-30 nm as required.
6. The system for calibrating and testing the harmonic flexspline torque sensor according to claim 1, wherein the standard torque sensor module comprises a high-precision torque sensor (18), a high-precision torque sensor mounting rack (19) and a collecting instrument; the standard torque sensor is fixedly connected to one sliding seat module through a high-precision torque sensor mounting frame, and a torque value of the standard torque sensor is uploaded to an upper computer for processing through a collecting instrument in real time.
7. The calibration testing system of the harmonic flexible gear torque sensor as claimed in claim 1, wherein the weight loading arm module comprises a bracket (24) with a bearing, a long arm (25) with a key slot mounting hole for a flange mounting surface, and a plurality of weights (26) for loading;
wherein, the bracket (24) with the bearing comprises a bracket plate (24-1), a bearing (24-2), a bearing pressure plate (24-3), a shaft sleeve (24-4) and a set screw (24-5); the bearing pressing plate (24-3) fixedly arranges the outer ring of the bearing (24-2) in the support plate (24-1), and the shaft sleeve (24-4) is fixed with the inner ring of the bearing (24-2); the support plate (24-1) is fixed on the upper surface of the movable base module (1);
the key slot mounting hole is formed in one end of the long arm (25), and the long arm (25) is locked with an output shaft of the standard torque sensor (18) through a key (24-6), a shaft sleeve (24-4) and a set screw (24-5); a loading weight (26) is provided at the other end of the long arm (25).
8. A calibration method of a calibration test system according to any one of claims 1 to 7, wherein the calibration method comprises static calibration and dynamic calibration verification, and specifically comprises the following steps:
step 1: installing a joint module or a speed reducer containing a harmonic flexible gear torque sensor to be detected on a calibration rack, and enabling an output shaft of the joint module or the speed reducer to be coaxially connected with an input shaft at one end of a standard torque sensor through a diaphragm coupler, wherein an output shaft at the other end of the standard torque sensor is fixedly connected with a weight loading arm, and the weight loading arm is kept relatively horizontal; the joint module or the output shaft of the speed reducer is locked through the brake of the band-type brake, and the position reading fed back by the encoder of the output shaft of the joint module or the speed reducer is set to be a zero position;
step 2: loading a weight to one end of a weight loading arm; at this time, the torque T exerted by the weight is calculated by the effective arm length of the loading arm and the weight of the weight to be loaded fa The standard torque sensor can accurately measure the applied torque T st And transmitted to an upper computer through a communication interface, and compared by T fa And T st If the difference between the two is within the error range, T st Values are available, and calibration can be continued; otherwise, checking whether the standard torque sensor instrument is damaged or not, checking whether the weight calculation of the added weight is correct or not, and checking whether the installation of the long arm rod is correct or not;
and 3, step 3: repeating the step 2, setting the interval of the calibration points according to the rated output torque of the harmonic reducer, ensuring that the number of the calibration points is not less than 10, then loading weights step by step according to the torque value set by the calibration points until the reading of the standard torque sensor is stable, and finishing one-time loading; each time a corresponding torque value T is loaded st The output voltage signals collected from the harmonic flexible gear torque sensor to be calibrated can also be transmitted to the upper computer in real time; torque value T of weight gravity in loading process sti And the output voltage value U of the harmonic flexible gear torque sensor to be calibrated i The mathematical model between is: t is sti ＝k 0i +k 1i U i (ii) a Subscript i denotes the ith load;
and 4, step 4: after the loading calibration of all calibration points is finished, establishing a calibration model on the upper computer by adopting a least square method according to the mathematical model in the step 3, realizing the calibration of the harmonic flexible gear torque sensor to be calibrated, and obtaining a loading calibration coefficient k of the sensor 0i ，k 1i Completing one-time loading calibration;
and 5: step-by-step unloading the loaded weights according to the number of the calibration points determined in the step (3) in the opposite direction, uploading the torque value of the standard torque sensor and the output voltage value of the harmonic flexible wheel torque sensor to be calibrated to an upper calibration program after the system is stabilized, and realizing unloading calibration to obtain a primary unloading calibration coefficient;
step 6: repeating the steps to finish at least 5 times of loading calibration and at least 5 times of unloading calibration, averaging the obtained calibration coefficients and taking the averaged calibration coefficients as the calibration coefficients k of the fitting straight line at the position, namely the zero position 0 ，k 1 ；
And 7: due to the calibration coefficient k 0 Is changed in a sine wave mode along with the change of the position of the wave generator of the harmonic reducer, so that the proper k is fitted 0 A sine curve graph, wherein the calibration positions are uniformly subdivided in the circumferential direction, and the angle between two adjacent calibration positions is set as alpha; after completing the calibration of one position, controlling the motor to rotate by alpha degrees, and then repeating the steps 2-6 to obtain a group of calibration coefficients k of a new calibration position 0 ，k 1 ；
And 8: repeating the step 7 until the calibration of all the calibration positions is completed; wherein, as with zero calibration, each calibration position completes at least 5 times of loading calibration and at least 5 times of unloading calibration, and the obtained calibration coefficients are averaged; fitting a smooth sinusoidal curve to the average value of each position, wherein each position on the curve corresponds to a unique set of torque coefficients k 0 ，k 1 And correspond to the absolute position encoder position one by one;
and step 9: unloading the weight loading arm module from the loading end of the standard torque sensor, and coaxially connecting the hysteresis moment loader module with the standard torque sensor module by using a diaphragm coupling;
step 10: reading in a calibration coefficient of static calibration and a related sinusoidal coefficient obtained by fitting; and controlling the hysteresis moment loader to load different moments as the load moment of the joint module to be tested, and dynamically verifying and calibrating whether the harmonic flexible gear torque sensor to be tested is within an error range by comparing the moment loaded by the hysteresis moment loader, the moment measured by the standard torque sensor and the moment measured by the harmonic flexible gear torque sensor.
9. A calibration method for calibrating a test system according to claim 8, wherein in step 7, α is 15 °.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117053654A (en) * | 2023-10-12 | 2023-11-14 | 航天江南集团有限公司 | Loading device of unmanned aerial vehicle servo mechanism |
| CN117148149A (en) * | 2023-10-30 | 2023-12-01 | 中汽研汽车检验中心(宁波)有限公司 | Environment bin suitable for different motor mounting modes |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117053654A (en) * | 2023-10-12 | 2023-11-14 | 航天江南集团有限公司 | Loading device of unmanned aerial vehicle servo mechanism |
| CN117053654B (en) * | 2023-10-12 | 2023-12-12 | 航天江南集团有限公司 | Loading device of unmanned aerial vehicle servo mechanism |
| CN117148149A (en) * | 2023-10-30 | 2023-12-01 | 中汽研汽车检验中心(宁波)有限公司 | Environment bin suitable for different motor mounting modes |
| CN117148149B (en) * | 2023-10-30 | 2024-02-06 | 中汽研汽车检验中心(宁波)有限公司 | Environment bin suitable for different motor mounting modes |
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Address after: 317600 Yucheng street, Yuhuan City, Taizhou, Zhejiang. Applicant after: Zhejiang Huandong Robot Joint Technology Co.,Ltd. Address before: 317600 Yucheng street, Yuhuan City, Taizhou, Zhejiang. Applicant before: Zhejiang environmental Robot Joint Technology Co.,Ltd. |