CN109015646B - Position information self-calibration method, device, equipment and storage medium - Google Patents
Position information self-calibration method, device, equipment and storage medium Download PDFInfo
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- CN109015646B CN109015646B CN201810958727.9A CN201810958727A CN109015646B CN 109015646 B CN109015646 B CN 109015646B CN 201810958727 A CN201810958727 A CN 201810958727A CN 109015646 B CN109015646 B CN 109015646B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
- B25J9/00—Programme-controlled manipulators
- B25J9/16—Programme controls
- B25J9/1679—Programme controls characterised by the tasks executed
- B25J9/1692—Calibration of manipulator
Abstract
The embodiment of the invention discloses a position information self-calibration method, a device, equipment and a storage medium. The method comprises the following steps: respectively acquiring the position information of the high speed end of the speed reducer and the position information of the low speed end of the speed reducer in the process that the mechanical arm joint rotates in two opposite directions based on the same joint initial position; and aiming at each direction, automatically calibrating the position information of the low-speed end of the speed reducer in the direction by adopting the position information of the high-speed end of the speed reducer in the direction to obtain a self-calibration result of the position information of the low-speed end of the speed reducer. The embodiment of the invention realizes the automatic calibration of the position information of the low-speed end of the speed reducer by adopting the position information of the high-speed end of the speed reducer, avoids the dependence of a specific mechanical arm on a specific calibration flow released by a manufacturer during the position calibration, reduces the labor cost in the position information calibration process, and improves the calibration efficiency and accuracy of the position information.
Description
Technical Field
The embodiment of the invention relates to the technical field of mechanical arms, in particular to a position information self-calibration method, device, equipment and storage medium.
Background
With the development of the mechatronic technology, industrial products develop towards the direction of intellectualization, systematization, miniaturization, modularization and man-machine cooperation. Particularly in the field of mechanical arms, the mechanical arms have the development trends of high precision, modularization, light weight and multiple degrees of freedom.
The mechanical arm basically simulates the arm of a human body, and related tasks are executed through rotation of the mechanical arm joint. When the mechanical arm executes a task, high-precision absolute positioning precision is required according to the position sensor integrated in the mechanical arm, so that the accurate grabbing and placing of objects in the industrial production process and other processing operations are realized. Currently, in order to make the position sensor information accurate as much as possible, the prior art generally improves the accuracy of the position sensor information by optimizing the installation mode. Or the position sensor manufacturer can design corresponding calibration software or calibration flow aiming at the product of the position sensor manufacturer, and when the worker finishes calibration according to the calibration software or the calibration flow, the calibration result is integrated into the position sensor so as to improve the reading precision of the position sensor.
However, in the prior art, even if the installation mode is optimized, hardware errors generated in the installation process of the mechanical arm cannot be completely avoided. The existing calibration software and calibration flow have strong pertinence to specific mechanical arms, and when a specific mechanical arm is adopted, a worker needs to use the corresponding calibration software and calibration flow, so that the calibration process is complicated, the calibration is completely carried out by the worker, and the labor cost is high.
Disclosure of Invention
The embodiment of the invention provides a position information self-calibration method, a position information self-calibration device, position information self-calibration equipment and a storage medium, which can automatically calibrate position information acquired by a low-speed position sensor of a speed reducer.
In a first aspect, an embodiment of the present invention provides a position information self-calibration method, including:
respectively acquiring the position information of the high speed end of the speed reducer and the position information of the low speed end of the speed reducer in the process that the mechanical arm joint rotates in two opposite directions based on the same joint initial position;
and aiming at each direction, automatically calibrating the position information of the low-speed end of the speed reducer in the direction by adopting the position information of the high-speed end of the speed reducer in the direction to obtain a self-calibration result of the position information of the low-speed end of the speed reducer.
In a second aspect, an embodiment of the present invention provides a position information self-calibration apparatus, including:
the position information acquisition module is used for respectively acquiring the position information of the high speed end of the speed reducer and the position information of the low speed end of the speed reducer in the process that the mechanical arm joint rotates in two opposite directions based on the same joint initial position;
and the self-calibration module is used for automatically calibrating the position information of the low-speed end of the speed reducer in each direction by adopting the position information of the high-speed end of the speed reducer in the direction to obtain a self-calibration result of the position information of the low-speed end of the speed reducer.
In a third aspect, an embodiment of the present invention provides an apparatus, including:
one or more processors;
a memory for storing one or more programs;
when the one or more programs are executed by the one or more processors, the one or more processors implement the position information self-calibration method according to any embodiment of the present invention.
In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium, on which a computer program is stored, where the computer program, when executed by a processor, implements the position information self-calibration method according to any embodiment of the present invention.
According to the embodiment of the invention, the mechanical arm joints are controlled to rotate in two mutually opposite directions based on the same joint initial position respectively, the high-speed end position information and the low-speed end position information of the speed reducer in the rotating process are collected, and the high-speed end position information of the speed reducer in the direction is adopted to automatically calibrate the low-speed end position information of the speed reducer in the direction aiming at each direction. According to the embodiment of the invention, the self-calibration model is established by analyzing the data of the position information of the high speed end of the speed reducer and the position information of the low speed end of the speed reducer, so that the automatic calibration of the position information of the low speed end of the speed reducer by adopting the position information of the high speed end of the speed reducer is realized, the dependence of a specific mechanical arm on a specific calibration flow released by a manufacturer during the position calibration is avoided, the labor cost in the position information calibration process is reduced, and the calibration efficiency and accuracy of the position information are improved.
Drawings
Fig. 1 is a flowchart of a position information self-calibration method according to an embodiment of the present invention;
fig. 2 is a flowchart of a position information self-calibration method according to a second embodiment of the present invention;
fig. 3 is an exemplary diagram of original values of position information of a high-speed end of a speed reducer and position information of a low-speed end of the speed reducer according to a second embodiment of the present invention;
FIG. 4 is an exemplary illustration of a position sensor reading unified to a decelerator low speed end angle system provided in accordance with a second embodiment of the present invention;
FIG. 5 is a simplified reducer equivalent model according to a second embodiment of the present invention;
fig. 6 is an exemplary diagram of a difference signal between position information of a high-speed end of a speed reducer and position information of a low-speed end of the speed reducer according to a second embodiment of the present invention;
fig. 7 is an exemplary diagram after performing fourier transform on the difference signal according to the second embodiment of the present invention;
FIG. 8 is an exemplary diagram of a fitting result of a difference signal according to a second embodiment of the present invention;
FIG. 9 is a diagram illustrating a comparison between error compensation and error compensation provided by a third embodiment of the present invention;
fig. 10 is a flowchart of a position information self-calibration method according to a third embodiment of the present invention;
fig. 11 is a schematic structural diagram of a position information self-calibration apparatus according to a fourth embodiment of the present invention;
fig. 12 is a schematic structural diagram of an apparatus according to a fifth embodiment of the present invention.
Detailed Description
The embodiments of the present invention will be described in further detail with reference to the drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the embodiments of the invention and that no limitation of the invention is intended. It should be further noted that, for convenience of description, only some structures, not all structures, relating to the embodiments of the present invention are shown in the drawings.
Example one
Fig. 1 is a flowchart of a position information self-calibration method according to an embodiment of the present invention, where the embodiment is applicable to automatically calibrating a position sensor in a robot joint, and the method may be executed by a position information self-calibration apparatus. The method specifically comprises the following steps:
and 110, respectively acquiring the position information of the high speed end of the speed reducer and the position information of the low speed end of the speed reducer in the process that the mechanical arm joint rotates in two opposite directions based on the same joint initial position.
In a specific embodiment of the present invention, a servo control system, a motor, a speed reducer, and a position sensor are at least installed in a robot joint, and the method for automatically calibrating the position information of the low-speed end of the speed reducer in this embodiment is integrated into the servo control system. The high-speed end of the speed reducer is directly connected with the servo control system and used as the input of the speed reducer, and the rotation of the low-speed end of the speed reducer is controlled through the transmission relation between the high-speed end of the speed reducer and the low-speed end of the speed reducer. Correspondingly, the high-speed end of the speed reducer has high precision and accurate position information, and the position information can be measured in various ways and used as a reference for calibrating the position information of the low-speed end of the speed reducer. Therefore, the position sensor in the mechanical arm joint at least comprises a speed reducer low-speed end position sensor, and the position sensor is used for acquiring the position information of the speed reducer low-speed end.
In this embodiment, at least the following three ways can be adopted for acquiring the position information of the high-speed end of the speed reducer. The first method is that a position sensor is also arranged at the high-speed end of the speed reducer to directly acquire the position information of the high-speed end of the speed reducer, namely the acquired pulse information is converted into a position angle numerical value. And secondly, for a permanent magnet motor or a stepping motor, a motor driver is controlled to work in a current control mode, three-phase sinusoidal current is input to a motor stator winding, so that the rotation of a motor rotor can be controlled in an open loop mode, and the phase position of the three-phase current can be approximately equal to the position of the motor rotor at the high-speed end of the speed reducer. And the third method is to estimate the position information of the high-speed end of the speed reducer by using a position sensorless control method, which includes but is not limited to a position estimation method based on back electromotive force, a position estimation method based on high-frequency injection, and a position estimation method based on short-time power failure. It should be noted that the manner of acquiring the position information of the high-speed end of the speed reducer in the present embodiment is not limited to the three manners described above.
Specifically, the present embodiment describes the self-calibration method of the present embodiment by taking a first acquisition manner of the position information of the high-speed end of the speed reducer as an example. In the self-calibration process of this embodiment, the servo control system is used to control the mechanical arm joint to rotate at any angle in any direction at any speed within the rated speed range from the joint initial position, and record the position information of the high speed end of the speed reducer and the position information of the low speed end of the speed reducer during the rotation process, and use the position information as the self-calibration basis in the first direction. And secondly, controlling the joint of the mechanical arm to return to the same joint initial position as that in the first direction rotation, and rotating the mechanical arm in the opposite direction by a certain angle, wherein the sum of the angle and the angle of the first rotation is not less than 360 degrees. And similarly, respectively recording the position information of the high speed end of the speed reducer and the position information of the low speed end of the speed reducer in the rotation process in the opposite direction, and taking the position information as the basis of self-calibration in the second direction. If other speed reducer high-speed end position information acquisition modes are adopted, any speed in a rated speed range can be correspondingly converted into current in any direction in a click rated current range, and the same effect can be achieved.
Illustratively, the mechanical arm joint is controlled to rotate 90 degrees in a first direction at any speed within a rated speed range from the initial position of the joint, and the position information of the high-speed end of the speed reducer and the position information of the low-speed end of the speed reducer in the rotation process of the first direction are measured. And secondly, controlling the mechanical arm joint to return to the joint initial position and rotate 270 degrees in the opposite direction of the first direction, and measuring to obtain the position information of the high speed end of the speed reducer and the position information of the low speed end of the speed reducer in the opposite direction rotating process. The collected position information can be displayed in a two-dimensional coordinate graph with time as an abscissa and position information as an ordinate.
In this embodiment, before calibrating the position information of the low-speed end of the speed reducer, the original reading data is converted into an international unit angle, and the position information of the high-speed end of the speed reducer is standardized according to the transmission relationship between the high-speed end of the speed reducer and the low-speed end of the speed reducer, so as to obtain the position information of the high-speed end of the speed reducer uniformly aligned with the position information of the low-speed end of the speed reducer.
For example, the transmission relationship of N to 1 between the high-speed end and the low-speed end of the speed reducer is assumed, that is, when the high-speed end of the speed reducer rotates N circles, the low-speed end of the speed reducer rotates 1 circle. Therefore, in the case where the high-speed end of the speed reducer and the low-speed end of the speed reducer are converted to adopt the same international unit angle system, the numerical value of the high-speed end position information of the speed reducer is divided by N to obtain the high-speed end position information of the speed reducer which is aligned with the low-speed end position information of the speed reducer in a unified manner.
And 120, aiming at each direction, automatically calibrating the position information of the low-speed end of the speed reducer in the direction by adopting the position information of the high-speed end of the speed reducer in the direction, and obtaining a self-calibration result of the position information of the low-speed end of the speed reducer.
In the specific embodiment of the invention, aiming at the position information collected in each rotating direction, the position information of the high-speed end of the speed reducer in the direction is adopted to automatically calibrate the position information of the low-speed end of the speed reducer in the direction, and the self-calibration is independently carried out twice respectively.
Specifically, a difference signal between the normalized high-speed end position information of the speed reducer and the normalized low-speed end position information of the speed reducer is obtained; curve fitting is performed on the difference signal, and a functional representation and an offset value for representing the difference signal are determined. Wherein a variety of mathematical models may be used to fit the representation of the difference signal. In the embodiment, since the waveform of the difference signal is similar to a trigonometric function, it is preferable to perform fourier analysis on the difference signal to determine the order of the fourier series model used for fitting; and according to the determined order, performing curve fitting on the difference signal by adopting a least square method, and determining a bias value for representing the difference signal. And finally, obtaining the self-calibration result of the corrected low-speed end position information of the speed reducer according to the two self-calibration results in two opposite directions.
In the embodiment, when the position information of the mechanical arm joint needs to be calibrated, the servo control system is used for automatically calibrating the position information, so that the offline calibration of the position information of the low-speed end of the speed reducer is completed. And then when the mechanical arm joint normally operates, error compensation can be carried out on the position information of the low-speed end of the speed reducer in real time according to the self-calibration result of the position information of the low-speed end of the speed reducer.
According to the technical scheme, the mechanical arm joints are controlled to rotate in two opposite directions respectively, the position information of the high-speed end of the speed reducer and the position information of the low-speed end of the speed reducer in the rotating process are collected, and the position information of the low-speed end of the speed reducer in the direction is automatically calibrated by adopting the position information of the high-speed end of the speed reducer in the direction aiming at each direction. According to the embodiment of the invention, the self-calibration model is established by analyzing the data of the position information of the high speed end of the speed reducer and the position information of the low speed end of the speed reducer, so that the automatic calibration of the position information of the low speed end of the speed reducer by adopting the position information of the high speed end of the speed reducer is realized, the dependence of a specific mechanical arm on a specific calibration flow released by a manufacturer during the position calibration is avoided, the labor cost in the position information calibration process is reduced, and the calibration efficiency and accuracy of the position information are improved.
Example two
The present embodiment provides a preferred implementation of the position information self-calibration method based on the first embodiment, and can implement the construction of the self-calibration model by performing curve fitting on the difference signal. Fig. 2 is a flowchart of a position information self-calibration method according to a second embodiment of the present invention, and as shown in fig. 2, the method includes the following specific steps:
and step 210, respectively acquiring the position information of the high speed end of the speed reducer and the position information of the low speed end of the speed reducer in the process that the mechanical arm joint rotates in two opposite directions based on the same joint initial position.
In the embodiment of the invention, the mechanical arm joint is controlled by a servo control system to rotate at any first angle in any first direction at any speed within a rated speed range from the joint initial position, the position information of the high-speed end of the speed reducer and the position information of the low-speed end of the speed reducer in the rotation process are respectively recorded, and the position information is used as the basis of the first self-calibration. And secondly, controlling the mechanical arm joint to return to the joint initial position and rotate by a second angle in the direction opposite to the first direction, respectively recording the position information of the high speed end of the speed reducer and the position information of the low speed end of the speed reducer in the second rotation process, and taking the position information as the basis of the second self-calibration. The sum of the angles of rotation of the mechanical arm joints in two opposite directions is not less than 360 degrees, namely the sum of the first angle and the second angle is not less than 360 degrees.
Illustratively, the position sensor is also used for acquiring the position information of the high-speed end of the speed reducer, taking self-calibration for the first time as an example. And assuming that the mechanical arm joint is controlled to rotate 360 degrees in any first direction at any speed within the rated speed range, and simultaneously recording the position information of the high-speed end of the speed reducer and the position information of the low-speed end of the speed reducer. The original values of the position information of the high speed end of the speed reducer and the position information of the low speed end of the speed reducer are shown in fig. 3, wherein time is used as an abscissa, and a pulse value detected by the position sensor is used as an ordinate.
And step 220, carrying out standardized processing on the position information of the high-speed end of the speed reducer according to the transmission relation between the high-speed end of the speed reducer and the low-speed end of the speed reducer, and obtaining the position information of the high-speed end of the speed reducer which is aligned with the position information of the low-speed end of the speed reducer in a unified way.
In the embodiment of the present invention, after the position information of the high speed end of the speed reducer and the position information of the low speed end of the speed reducer are collected, if the position information of the high speed end of the speed reducer is collected by the position sensor, the original pulse value collected by the position sensor is converted into the international unit angle according to the related configuration information such as the resolution of the position sensor, for example, according to the formula (pulse value/2)n) X 360 ° to yield. If the position information of the high-speed end of the speed reducer is acquired in other acquisition modes, the conversion of the original results such as the three-phase current phase is also carried out. The present embodiment does not enumerate the conversion relationships in numerical units. Secondly, according to the transmission relation between the high-speed end and the low-speed end of the speed reducer, the position information of the high-speed end of the speed reducer is subjected to standardization processing.
For example, fig. 4 is an exemplary diagram of readings of a position sensor unified to an angle system of a low-speed end of a speed reducer, in the above example, assuming that a transmission relationship between a high-speed end of the speed reducer and a low-speed end of the speed reducer is N to 1, when the high-speed end of the speed reducer and the low-speed end of the speed reducer are converted to adopt the same international unit angle system, a value of position information of the high-speed end of the speed reducer is divided by N to obtain position information of the high-speed end of the speed reducer uniformly aligned with the position information of the low-speed end of the speed reducer. As can be seen from fig. 4, all the position information is converted into international unit angles (°), and the position information of the high speed end of the speed reducer is subjected to normalization processing.
And step 230, acquiring a difference signal between the normalized high-speed end position information of the speed reducer and the normalized low-speed end position information of the speed reducer.
In the embodiment of the invention, unified and standardized position information data of unit conversion is processed, the unified high-speed end position information of the speed reducer is subtracted by the low-speed end position information of the speed reducer, and a difference signal is used as reading error information between two position sensors.
Exemplarily, in the above example, it is assumed that pos _ high represents raw reading information of the position sensor at the high-speed end of the speed reducer, and pos _ low represents raw reading information of the position sensor at the low-speed end of the speed reducer; pos _ high _ real represents the reading of the high-speed end position sensor of the speed reducer under the assumption of an ideal condition, and pos _ low _ real represents the reading of the low-speed end position sensor of the speed reducer under the assumption of an ideal condition; pos _ high _ err represents error information included in the readings of the high-speed end position sensor of the speed reducer, and pos _ low _ err represents error information included in the readings of the low-speed end position sensor of the speed reducer. The difference signal error can be expressed as:
error＝pos_high－pos_low
＝(pos_high_real+pos_high_err)－(pos_low_real+pos_low_err)
＝(pos_high_real－pos_low_real)+(pos_high_err－pos_low_err)。
as can be seen from the above formula, the difference signal mainly includes two parts, i.e., the ideal position information difference and the error information difference.
In the method, the position difference between two ends of the speed reducer is represented by an ideal position information difference value under the ideal condition that the position sensor information of the high-speed end and the low-speed end of the speed reducer reflects real and error-free angle information. In general, the reducer can be equivalent to a pure spring model, as shown in fig. 5. According to the spring model τ K · Δ θ, τ represents the torsional moment, K represents the spring constant, and Δ θ represents the difference between the two end positions. It is understood that Δ θ can be used to describe the torque transmitted by the reducer, and when the arm joint rotates at a constant speed (or current) without load, the torque transmitted by the reducer is a constant torque. Thus, Δ θ is pos _ high _ real-pos _ low _ real — c, where c is a constant.
However, fig. 6 is a diagram illustrating an example of a difference signal between the decelerator high-speed end position information and the decelerator low-speed end position information. As can be seen from fig. 6, the position sensor difference signal does not satisfy the constant condition, and thus the error information difference needs to be analyzed.
In an embodiment of the present invention, the difference signal may be fitted by using various mathematical models, such as an exponential function, a logarithmic function, a gaussian curve, and the like. The embodiment analyzes the difference signal, and finds that the periodic signal of the difference signal about the position information of the low-speed end of the speed reducer shows a characteristic similar to a trigonometric function, as shown in fig. 6. Therefore, the present embodiment preferably uses a fourier series model to fit the difference signal.
Optionally, fourier analysis is performed on the difference signal, and the order of a fourier series model used for fitting is determined; and according to the determined order, performing curve fitting on the difference signal by adopting a least square method, and determining a bias value for representing the difference signal.
In the specific embodiment of the invention, after the difference signal is fitted by using the fourier series model, the order of the fourier series is determined first, that is, the difference signal is subjected to fourier analysis, the range of the order of the series signal which is covered in the difference signal and is related to the position information of the low-speed end of the speed reducer is determined, and a frequency band which is more significant is selected as the order of the fourier series.
Illustratively, in the above example, fig. 7 is an exemplary diagram after fourier transform is performed on the difference signal. It can be known from the figure that the low-speed end position information of the speed reducer does not start to attenuate the series response covered by the difference signal until 4 times of frequency is multiplied, and the series response is ignored. It was therefore determined that a functional representation of the difference signal was fitted with a fourth order fourier series signal.
In the embodiment, the low-speed end error signal pos _ low _ err is firstly analyzed, and when the low-speed end position sensor is installed, reading errors are often generated due to installation problems (such as shaft runout and the like) and reading fluctuation caused by the problems of the position sensor. Because the error belongs to the problem of mechanical hardware, the error signal is a periodic signal taking one rotation of the low-speed end of the speed reducer as a period and corresponds to the position of the low-speed end of the speed reducer one by one. Further, the error information included in the low-speed end position sensor reading may be represented as pos _ low _ err ═ f (pos _ low). Wherein f (#) represents establishing a functional relationship between the low-speed end position and the low-speed end error. As can be seen from the difference signal in fig. 6, as the low-speed end of the speed reducer rotates from 0 ° to-360 ° at a constant speed, the difference signal includes an error curve similar to a trigonometric function characteristic, and therefore this portion is taken as an error signal generated by the low-speed end.
Secondly, analyzing the high-speed end error signal pos _ high _ err, the high-speed end position sensor can also generate error fluctuation on reading due to mechanical installation problems, but due to the existence of the speed reducer, position change and speed change generated by all high-speed ends can be scaled according to the transmission relationship of the speed reducer, namely the speed reduction ratio N. That is, assuming that the high speed end is shifted by 1 ° in angle, the angle shift reflected to the low speed end after the reduction gear transmission is 1/N °. Therefore, it can be considered that the amplitude of the error fluctuation signal due to the high speed side is extremely small after being unified to the low speed side. Also due to the reducer, after the low-speed end rotates one turn, the high-speed end actually rotates N turns, i.e. the high-speed end error signal pos _ high _ err has passed N cycles. Therefore, after the final normalization is performed to the low speed end, a high frequency fluctuation signal similar to noise with smaller amplitude and higher frequency appears in the difference signal. Furthermore, as can be seen from the difference signal in fig. 6, although the graph includes signals very similar to the description, the amplitude of the error signal pos _ high _ err caused by the low-speed end is very small after the reduction gear scaling, so this embodiment ignores this part of the error signal, that is, pos _ high _ err is 0.
In summary, the difference signal error is f (pos _ low) + c, and the modeling process for the difference signal is completed. The function f (×) is curve-fitted by the least square method, and the fitting result of the difference signal is shown in fig. 8. In the curve fitting result of self-calibration in the first direction, g is adopted1(x) Representing the result of the function obtained by the first fitting, except for the fourth Fourier series g1(x) Besides, an offset result a is obtained at the same time1。
Similarly, after the rotation and self-calibration in the first direction are performed, the self-calibration is also performed in the opposite direction, and the data processing process is repeated to obtain the fourth-order fourier series g of the reverse rotation2(x) And bias result a2。
And step 250, obtaining the self-calibration result of the corrected low-speed end position information of the speed reducer according to the two self-calibration results in two opposite directions.
In the embodiment of the invention, when the mechanical arm is under the idle condition and the rotating speed is the same, the transmission torque of the reducer should have the same amplitude theoretically, and the change of the rotating direction only changes the magnitude of the offset value. Further, error ═ f (pos _ low) + c ═ g can be obtained1(pos_low)+a1，error＝f(pos_low)－c＝g2(pos_low)+a2. Due to the mechanical mounting that causes the error fluctuations, it can be considered that the number of stages in the function f (—) with respect to pos _ low is partially identical, i.e. g1(pos_low)＝g2(pos _ low). The only difference being the bias result a obtained by the fitting1And a2Thus can finally obtain
And then, the establishment of a complete self-calibration model is completed, and the self-calibration result of the corrected position information of the low-speed end of the speed reducer is obtained.
And step 260, carrying out real-time error compensation on the position information of the low-speed end of the speed reducer according to the self-calibration result of the position information of the low-speed end of the speed reducer.
In the specific embodiment of the invention, in the actual operation process of the mechanical arm joint, real-time error compensation needs to be performed on pos _ low _ err in the reducer low-speed end position information according to a self-calibration result of the reducer low-speed end position information, so that a real low-speed end position sensor reading pos _ low _ real under an ideal condition is obtained, that is, pos _ low _ real is pos _ low + pos _ low _ err. Further obtain an error compensation formula of
Wherein the sign in the error compensation formula is determined by the rotation direction.
Illustratively, in the above example, fig. 9 is an exemplary diagram of comparison before and after error compensation. The upper graph of fig. 9 is the difference signal between the raw reading of the retarder high end position sensor and the raw reading of the retarder low end position sensor. The signal curve corresponding to the thinner solid line in the lower graph of fig. 9 is the error signal of the low-speed end position information that needs to be compensated. Further, by subtracting the signal waveform corresponding to the thin solid line in the lower graph of fig. 9 from the waveform in the upper graph of fig. 9, the error signal can be compensated, and a signal curve corresponding to the thick solid line in the lower graph of fig. 9 can be obtained.
According to the technical scheme, the mechanical arm joints are controlled to rotate in two opposite directions based on the same joint initial position, the position information of the high-speed end of the speed reducer and the position information of the low-speed end of the speed reducer are collected in the rotating process, and for each direction, the difference signal of the position information of the high-speed end of the speed reducer and the position information of the low-speed end of the speed reducer is subjected to curve fitting through data analysis of the position information of the high-speed end of the speed reducer and the position information of the low-speed end of the speed reducer, so that function representation and offset numerical values used for representing the difference signal are determined. And finally, according to the two self-calibration results, obtaining a self-calibration result of the corrected low-speed end position information of the speed reducer, completing the establishment of a self-calibration model, and realizing the automatic calibration of the low-speed end position information of the speed reducer by adopting the high-speed end position information of the speed reducer. The embodiment of the invention avoids the dependence of a specific mechanical arm on a specific calibration process released by a manufacturer during position calibration, reduces the labor cost in the position information calibration process, and improves the calibration efficiency and accuracy of the position information. Meanwhile, a basis is provided for real-time error compensation of subsequent position information, and the accuracy of the position information is improved.
EXAMPLE III
The present embodiment provides a preferred implementation of the position information self-calibration method on the basis of the second embodiment, and can perform offline self-calibration on the mechanical arm. Fig. 10 is a flowchart of a position information self-calibration method according to a third embodiment of the present invention, and as shown in fig. 10, the method includes the following specific steps:
step 1001, controlling the joint of the mechanical arm to rotate at any angle within a rated speed range from the initial position of the joint;
step 1008, obtaining an offset value in the self-calibration result of the corrected low-speed end position information of the speed reducer according to two self-calibration results in two opposite directions based on the same joint initial position;
step 1009, calculating to obtain an error compensation model of the low-speed end position sensor of the speed reducer;
and step 1010, obtaining real position information of a low-speed end position sensor of the speed reducer by using the error compensation model.
According to the technical scheme, the mechanical arm joint is rotated in the first direction to perform first self-calibration, then the mechanical arm joint is rotated in the opposite direction of the first direction based on the same joint initial position to perform second self-calibration, the self-calibration model is built, and automatic calibration of the position information of the low speed end of the speed reducer by adopting the position information of the high speed end of the speed reducer is achieved. The embodiment of the invention avoids the dependence of a specific mechanical arm on a specific calibration process released by a manufacturer during position calibration, reduces the labor cost in the position information calibration process, and improves the calibration efficiency and accuracy of the position information. Meanwhile, a basis is provided for real-time error compensation of subsequent position information, and the accuracy of the position information is improved.
Example four
Fig. 11 is a schematic structural diagram of a position information self-calibration device according to a fourth embodiment of the present invention, which is applicable to the case of automatically calibrating a position sensor in a robot arm joint, and the device can implement the position information self-calibration method according to any embodiment of the present invention. The device specifically includes:
the position information acquisition module 1110 is configured to acquire position information of a high-speed end of a speed reducer and position information of a low-speed end of the speed reducer during rotation of a mechanical arm joint in two opposite directions based on the same joint initial position;
and a self-calibration module 1120, configured to, for each direction, automatically calibrate the position information of the low-speed end of the speed reducer in the direction by using the position information of the high-speed end of the speed reducer in the direction, so as to obtain a self-calibration result of the position information of the low-speed end of the speed reducer.
Further, the apparatus further comprises:
the data unification module 1130 is configured to, before the automatic calibration is performed on the position information of the low-speed end of the speed reducer in each direction by using the position information of the high-speed end of the speed reducer in the direction, perform a standardization process on the position information of the high-speed end of the speed reducer according to a transmission relationship between the high-speed end of the speed reducer and the low-speed end of the speed reducer, and obtain the position information of the high-speed end of the speed reducer which is aligned with the position information of the low-speed end of the speed reducer in a unified manner.
Optionally, the self-calibration module 1120 includes:
a difference signal obtaining unit 1121 configured to obtain a difference signal between normalized speed reducer high-speed end position information and speed reducer low-speed end position information;
a fitting unit 1122 for curve fitting the difference signal and determining a functional representation and a bias value representing the difference signal.
Optionally, the fitting unit 1122 includes:
the order determining subunit is used for carrying out Fourier analysis on the difference signal and determining the order of a Fourier series model adopted by fitting;
and the offset value determining subunit is used for performing curve fitting on the difference signal by adopting a least square method according to the determined order and determining an offset value for representing the difference signal.
Optionally, the self-calibration module 1120 includes:
and a result correcting unit 1123, configured to obtain a self-calibration result of the corrected low-speed end position information of the speed reducer according to two self-calibration results in two opposite directions.
Further, the apparatus further comprises:
and the error compensation module 1140 is configured to, for each direction, automatically calibrate the position information of the low-speed end of the speed reducer in the direction by using the position information of the high-speed end of the speed reducer in the direction, and perform error compensation on the position information of the low-speed end of the speed reducer in real time according to the self-calibration result of the position information of the low-speed end of the speed reducer after obtaining the self-calibration result of the position information of the low-speed end of the speed reducer.
Optionally, the sum of the angles of rotation of the mechanical arm joints in two directions opposite to each other based on the same joint initial position is not less than 360 degrees.
According to the technical scheme, through the mutual cooperation of all the functional modules, the functions of controlling the selection of the joints of the mechanical arm, collecting the position information, unifying the position information, analyzing the data, acquiring the difference information, determining the fitting model, determining the order of Fourier series, fitting the difference signal, correcting the offset value, constructing the self-calibration model, determining the error compensation model and the like are achieved. The embodiment of the invention avoids the dependence of a specific mechanical arm on a specific calibration process released by a manufacturer during position calibration, reduces the labor cost in the position information calibration process, and improves the calibration efficiency and accuracy of the position information. Meanwhile, a basis is provided for real-time error compensation of subsequent position information, and the accuracy of the position information is improved.
EXAMPLE five
Fig. 12 is a schematic structural diagram of an apparatus according to a fifth embodiment of the present invention. As shown in fig. 12, the apparatus specifically includes: one or more processors 1210, one processor 1210 being exemplified in fig. 12; the memory 1220 is used for storing one or more programs, and when the one or more programs are executed by the one or more processors 1210, the one or more processors 1210 are enabled to implement the position information self-calibration method according to any embodiment of the present invention. The processor 1210 and the memory 1220 may be connected by a bus or other means, such as a bus connection in fig. 12.
The memory 1220, which is a computer-readable storage medium, may be used for storing software programs, computer-executable programs, and modules, such as program instructions corresponding to the position information self-calibration method in the embodiment of the present invention (for example, the rotation and position information acquisition of the mechanical arm joint and the self-calibration of the low-speed position information of the decelerator). The processor 1210 executes various functional applications and data processing of the device by executing software programs, instructions and modules stored in the memory 1220, so as to implement the above-mentioned position information self-calibration method.
The memory 1220 may mainly include a storage program area and a storage data area, wherein the storage program area may store an operating system, an application program required for at least one function; the storage data area may store data created according to use of the device, and the like. Further, the memory 1220 may include high speed random access memory, and may also include non-volatile memory, such as at least one magnetic disk storage device, flash memory device, or other non-volatile solid state storage device. In some examples, the memory 1220 can further include memory located remotely from the processor 1210, which can be connected to devices over a network. Examples of such networks include, but are not limited to, the internet, intranets, local area networks, mobile communication networks, and combinations thereof.
EXAMPLE six
An embodiment of the present invention further provides a computer-readable storage medium, on which a computer program (or referred to as computer-executable instructions) is stored, where the computer program is used for executing a method for self-calibrating location information when executed by a processor, and the method includes:
respectively acquiring the position information of the high speed end of the speed reducer and the position information of the low speed end of the speed reducer in the process that the mechanical arm joint rotates in two opposite directions based on the same joint initial position;
and aiming at each direction, automatically calibrating the position information of the low-speed end of the speed reducer in the direction by adopting the position information of the high-speed end of the speed reducer in the direction to obtain a self-calibration result of the position information of the low-speed end of the speed reducer.
Of course, the computer-readable storage medium provided in the embodiments of the present invention has computer-executable instructions that are not limited to the method operations described above, and may also perform related operations in the position information self-calibration method provided in any embodiments of the present invention.
From the above description of the embodiments, it is obvious for those skilled in the art that the embodiments of the present invention can be implemented by software and necessary general hardware, and certainly can be implemented by hardware, but the former is a better implementation in many cases. Based on such understanding, the technical solutions of the embodiments of the present invention may be embodied in the form of a software product, which may be stored in a computer-readable storage medium, such as a floppy disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a FLASH Memory (FLASH), a hard disk or an optical disk of a computer, and includes several instructions to make a computer device (which may be a personal computer, a server, or a network device) execute the methods according to the embodiments of the present invention.
It should be noted that, in the embodiment of the apparatus, the included units and modules are merely divided according to functional logic, but are not limited to the above division as long as the corresponding functions can be implemented; in addition, specific names of the functional units are only for convenience of distinguishing from each other, and are not used for limiting the protection scope of the present invention.
It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the embodiments of the present invention have been described in more detail through the above embodiments, the embodiments of the present invention are not limited to the above embodiments, and many other equivalent embodiments may be included without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.
Claims (8)
1. A position information self-calibration method is characterized by comprising the following steps:
respectively acquiring the position information of the high speed end of the speed reducer and the position information of the low speed end of the speed reducer in the process that the mechanical arm joint rotates in two opposite directions based on the same joint initial position;
aiming at each direction, automatically calibrating the position information of the low-speed end of the speed reducer in the direction by adopting the position information of the high-speed end of the speed reducer in the direction to obtain a self-calibration result of the position information of the low-speed end of the speed reducer;
aiming at each direction, the automatic calibration is carried out on the position information of the low-speed end of the speed reducer in the direction by adopting the position information of the high-speed end of the speed reducer in the direction, and the self-calibration result of the position information of the low-speed end of the speed reducer is obtained, and the method comprises the following steps:
obtaining a corrected self-calibration result of the position information of the low-speed end of the speed reducer according to the two self-calibration results in the two opposite directions;
after the automatic calibration is performed on the position information of the low-speed end of the speed reducer in each direction by adopting the position information of the high-speed end of the speed reducer in the direction, and a self-calibration result of the position information of the low-speed end of the speed reducer is obtained, the method further comprises the following steps:
according to the self-calibration result of the position information of the low-speed end of the speed reducer, carrying out real-time error compensation on the position information of the low-speed end of the speed reducer;
the error compensation formula is
Wherein pos _ low _ err represents error information contained in the reading of the low-speed end position sensor of the speed reducer;
the pos _ low represents the original reading information of the position sensor of the low-speed end speed reducer;
the error represents a difference signal;
c represents a constant;
f (pos _ low) represents establishing a functional relation between the low-speed end position and the low-speed end error;
the g (pos _ low) represents the result of fitting f (pos _ low);
a is a1Representing the bias result obtained by the first fitting;
a is a2Representing the bias result obtained by the second fitting;
the sign in the error compensation formula is determined by the direction of rotation.
2. The method according to claim 1, before automatically calibrating the position information of the low-speed end of the speed reducer in each direction by using the position information of the high-speed end of the speed reducer in the direction, the method further comprises:
and according to the transmission relation between the high-speed end of the speed reducer and the low-speed end of the speed reducer, carrying out standardization processing on the position information of the high-speed end of the speed reducer to obtain the position information of the high-speed end of the speed reducer which is aligned with the position information of the low-speed end of the speed reducer in a unified way.
3. The method according to claim 1, wherein the automatically calibrating the position information of the low-speed end of the speed reducer in each direction by using the position information of the high-speed end of the speed reducer in the direction comprises:
acquiring a difference signal between the normalized high-speed end position information and the normalized low-speed end position information of the speed reducer;
and performing curve fitting on the difference signal, and determining a function representation and an offset value for representing the difference signal.
4. The method of claim 3, wherein said curve fitting the difference signal to determine a functional representation and a bias value representing the difference signal comprises:
carrying out Fourier analysis on the difference signal, and determining the order of a Fourier series model adopted for fitting;
and according to the determined order, performing curve fitting on the difference signal by adopting a least square method, and determining a bias value for representing the difference signal.
5. The method according to claim 1, wherein the sum of angles of rotation of the robot joint in two directions opposite to each other based on the same joint initial position is not less than 360 degrees, respectively.
6. A position information self-calibration device is characterized by comprising:
the position information acquisition module is used for respectively acquiring the position information of the high speed end of the speed reducer and the position information of the low speed end of the speed reducer in the process that the mechanical arm joint rotates in two opposite directions based on the same joint initial position;
the self-calibration module is used for automatically calibrating the position information of the low-speed end of the speed reducer in each direction by adopting the position information of the high-speed end of the speed reducer in the direction to obtain a self-calibration result of the position information of the low-speed end of the speed reducer;
aiming at each direction, the automatic calibration is carried out on the position information of the low-speed end of the speed reducer in the direction by adopting the position information of the high-speed end of the speed reducer in the direction, and the self-calibration result of the position information of the low-speed end of the speed reducer is obtained, and the method comprises the following steps:
obtaining a corrected self-calibration result of the position information of the low-speed end of the speed reducer according to the two self-calibration results in the two opposite directions;
after the automatic calibration is performed on the position information of the low-speed end of the speed reducer in each direction by adopting the position information of the high-speed end of the speed reducer in the direction, and a self-calibration result of the position information of the low-speed end of the speed reducer is obtained, the method further comprises the following steps:
according to the self-calibration result of the position information of the low-speed end of the speed reducer, carrying out real-time error compensation on the position information of the low-speed end of the speed reducer;
the error compensation formula is
Wherein pos _ low _ err represents error information contained in the reading of the low-speed end position sensor of the speed reducer;
the pos _ low represents the original reading information of the position sensor of the low-speed end speed reducer;
the error represents a difference signal;
c represents a constant;
f (pos _ low) represents establishing a functional relation between the low-speed end position and the low-speed end error;
the g (pos _ low) represents the result of fitting f (pos _ low);
a is a1Representing the bias result obtained by the first fitting;
a is a2Representing the bias result obtained by the second fitting;
the sign in the error compensation formula is determined by the direction of rotation.
7. An apparatus, comprising:
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 the method of location information self-calibration as claimed in any one of claims 1 to 5.
8. A computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, carries out a method for self-calibration of position information according to any one of claims 1 to 5.
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| CN201810958727.9A CN109015646B (en) | 2018-08-22 | 2018-08-22 | Position information self-calibration method, device, equipment and storage medium |
| PCT/CN2019/081279 WO2020037989A1 (en) | 2018-08-22 | 2019-04-03 | Position information self-calibration method, storage medium, and computer device |
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| CN112287542B (en) * | 2020-10-28 | 2021-09-07 | 北京和德宇航技术有限公司 | Electric propeller calibration method, device, equipment and storage medium |
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