CN110312979A - The method, apparatus and computer system of multi-joint mechanism calibration - Google Patents
The method, apparatus and computer system of multi-joint mechanism calibration Download PDFInfo
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- CN110312979A CN110312979A CN201880012525.3A CN201880012525A CN110312979A CN 110312979 A CN110312979 A CN 110312979A CN 201880012525 A CN201880012525 A CN 201880012525A CN 110312979 A CN110312979 A CN 110312979A
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D3/00—Control of position or direction
- G05D3/12—Control of position or direction using feedback
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P5/00—Arrangements specially adapted for regulating or controlling the speed or torque of two or more electric motors
- H02P5/46—Arrangements specially adapted for regulating or controlling the speed or torque of two or more electric motors for speed regulation of two or more dynamo-electric motors in relation to one another
- H02P5/52—Arrangements specially adapted for regulating or controlling the speed or torque of two or more electric motors for speed regulation of two or more dynamo-electric motors in relation to one another additionally providing control of relative angular displacement
Abstract
A kind of method, apparatus and computer system of multi-joint mechanism calibration.The multi-joint mechanism includes n joint, this method comprises: m-th of joint of the multi-joint mechanism is individually rotated, wherein, m-th of joint is provided with angle feed-back element, the angle feed-back element is used to measure the joint angle in m-th of joint, and n and m are positive integer, 1≤m≤n；The joint angle in rotation m-th of joint front and back m-th of joint is obtained, and obtains the posture of the output end of rotation m-th of joint front and back multi-joint mechanism；According to the posture for the joint angle and the output end for rotating m-th of joint front and back m-th of joint, the axial direction of non-linear to the joint angle of the angle feed-back element of m-th of joint and m-th of joint shaft is demarcated.
Description
Copyright declaration
The disclosure of this patent document contains material which is subject to copyright protection. The copyright is owned by the copyright owner. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the patent and trademark office official records and records.
The present invention relates to the field of articulated mechanisms, and more particularly, to a method, an apparatus, and a computer system for calibrating an articulated mechanism.
With the continuous development of automation technology, a multi-joint angular motion platform, such as a multi-axis pan-tilt, has been widely applied in various fields such as industrial manufacturing, quality detection and the like, with the advantages of low cost, high precision, simple operation and the like.
The multi-joint control system mainly obtains each joint corner by a sensor arranged at the joint corner, and then calculates the position and the posture of the platform by combining a kinematic model of the multi-joint mechanism. Due to the precision limitation of the manufacturing process, the joints cannot be guaranteed to completely conform to the prior design in the axial direction after being assembled together, and axial errors are caused. On the other hand, in the multi-axis pan-tilt, there is a certain error in the measurement of the joint angle, for example, in the multi-axis pan-tilt, the joint angle is generally measured by one or more hall devices installed inside the joint motor, and due to factors such as installation position and magnetic field distortion, the measured joint angle generally deviates from its actual rotation angle, and such an error is called joint angle nonlinearity. The axial error and the joint angle nonlinearity pass through a kinematic model, so that the calculated platform position and attitude deviate from the actual values, and the final positioning accuracy is influenced.
Therefore, how to effectively calibrate the multi-joint mechanism becomes a technical problem to be solved urgently.
Disclosure of Invention
The embodiment of the invention provides a method and a device for calibrating a multi-joint mechanism and a computer system, which can improve the efficiency of calibrating the multi-joint mechanism.
In a first aspect, a method for calibrating a multi-joint mechanism, the multi-joint mechanism comprising n joints, is provided, the method comprising: independently rotating the mth joint of the multi-joint mechanism, wherein an angle feedback element is arranged at the mth joint and used for measuring the joint angle of the mth joint, n and m are positive integers, and m is greater than or equal to 1 and less than or equal to n; acquiring joint angles of the mth joint before and after the mth joint is rotated, and acquiring a posture of an output end of the multi-joint mechanism before and after the mth joint is rotated; and calibrating the joint angle nonlinearity of the angle feedback element at the mth joint and the axial direction of the rotating shaft of the mth joint according to the joint angle of the mth joint before and after the mth joint is rotated and the posture of the output end.
In a second aspect, there is provided a device for calibrating a multi-joint mechanism, the multi-joint mechanism comprising n joints, the device comprising: the rotation control module is used for independently rotating the mth joint of the multi-joint mechanism, wherein an angle feedback element is arranged at the mth joint and used for measuring the joint angle of the mth joint, n and m are positive integers, and m is greater than or equal to 1 and less than or equal to n; an acquisition module configured to acquire joint angles of the mth joint before and after the mth joint is rotated, and acquire a posture of an output end of the multi-joint mechanism before and after the mth joint is rotated; and the calibration module is used for calibrating the joint angle nonlinearity of the angle feedback element at the mth joint and the axial direction of the rotating shaft of the mth joint according to the joint angle of the mth joint before and after the mth joint is rotated and the posture of the output end.
In a third aspect, there is provided a computer system comprising: a memory for storing computer executable instructions; a processor for accessing the memory and executing the computer-executable instructions to perform the operations in the method of the first aspect described above.
In a fourth aspect, a computer storage medium is provided, in which program code is stored, the program code being operable to instruct execution of the method of the first aspect.
According to the technical scheme of the embodiment of the invention, the mth joint is independently rotated, the joint angle nonlinearity of the angle feedback element at the mth joint and the axial direction of the rotating shaft of the mth joint are calibrated according to the joint angle of the mth joint before and after the mth joint is rotated and the posture of the output end of the multi-joint mechanism, the axial direction and the joint angle nonlinearity can be simultaneously calibrated with a small calculated amount, and the calibration efficiency of the multi-joint mechanism can be improved.
Fig. 1 is a schematic view of a pan-tilt head to which the technical solution of the embodiment of the present invention is applied.
Fig. 2 is a schematic flow chart of a method of multi-joint mechanism calibration according to an embodiment of the invention.
FIG. 3 is a schematic of a non-linear function of an embodiment of the present invention.
Fig. 4 is a schematic diagram of the reciprocating rotation trajectory of the multi-joint structure according to the embodiment of the present invention.
FIG. 5 is a schematic diagram of zero offset error compensation according to an embodiment of the present invention.
Fig. 6 is a schematic block diagram of a device for multi-joint mechanism calibration according to an embodiment of the present invention.
Fig. 7 is a schematic block diagram of a multi-joint mechanism calibration apparatus according to another embodiment of the present invention.
FIG. 8 is a schematic block diagram of a computer system of an embodiment of the present invention.
The technical solution in the embodiments of the present invention will be described below with reference to the accompanying drawings.
It should be understood that the specific examples are included merely as a prelude to a better understanding of the embodiments of the present invention for those skilled in the art and are not intended to limit the scope of the embodiments of the present invention.
It should also be understood that the formula in the embodiment of the present invention is only an example, and is not intended to limit the scope of the embodiment of the present invention, and the formula may be modified, and the modifications should also fall within the protection scope of the present invention.
It should also be understood that, in various embodiments of the present invention, the sequence numbers of the processes do not mean the execution sequence, and the execution sequence of the processes should be determined by the functions and the internal logic of the processes, and should not constitute any limitation on the implementation process of the embodiments of the present invention.
It should also be understood that the various embodiments described in this specification may be implemented alone or in combination, and are not limited to the embodiments of the present invention.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the present application is for the purpose of describing particular embodiments only and is not intended to limit the scope of the present application. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
The technical scheme of the embodiment of the invention can be applied to various multi-joint mechanisms, such as a holder, a mechanical arm and the like. In the embodiment of the present invention, for convenience of description, a pan/tilt head is taken as an example for explanation, but the embodiment of the present invention is not limited thereto.
The carrier such as unmanned aerial vehicle because the motion of itself has the shake of high frequency or low frequency, can not directly hang the thing of bearing such as equipment of taking photo by plane, detecting instrument on the organism directly usually, but the stable platform of additional configuration satisfies the stability of carrying on, and this kind of carrier platform device is called the cloud platform. The pan-tilt system needs to provide a stable attitude to the carrier, so it is sufficient to consider movements in three degrees of freedom.
Fig. 1 shows a schematic view of a pan-tilt head to which the technical solution of the embodiment of the present invention is applied.
As shown in fig. 1, the stabilizing device of the pan/tilt head is installed by a dc brushless motor in a perpendicular manner, and forms three joint angles, which are respectively called an outer frame 1, an inner frame 2, and an inner frame 3. In the actual manufacturing and production process of the holder, the whole holder system can be hung on the machine body, the outer frame 1 is fixedly connected with the machine body and is orthogonally installed with the rotating shaft of the middle frame 2, and the rotating shaft of the inner frame 3 is orthogonally installed with the middle frame 2 and is fixedly connected with the load end 4. After the pan-tilt head is installed, the axial vector of each motor is fixed, and only the axial rotation angle of the motor changes during rotation, wherein k represents the k first joint. It should be understood that the pan/tilt head shown in fig. 1 includes 3 joints, but the technical solution of the embodiment of the present invention may be applied to a multi-joint mechanism with more joints, and the embodiment of the present invention is not limited thereto.
Each brushless DC motor is provided with an angle feedback element, also called an angle sensor, such as a Hall element or a photoelectric encoder, which can measure the angle of the rotating shaft, so as to determine the axial rotation angle of the motor, namely the k-th joint angle rotation angle thetakThen according to the kth fixed axial vector ωkAnd obtaining the attitude information between the joint and the (k-1) th joint.
However, due to the limitations of the manufacturing accuracy and the installation deviation of the components, the deviation of the rotation axis of the joint angle from the pre-designed absolute orthogonality cannot be guaranteed, so in the tripod head scene, the axial deviation is also called as axial non-orthogonality, and the axial direction calibration is needed to obtain the real axial vector ωk(ii) a In addition, errors in the mounting position of the angle feedback element, as well as distortions in the magnetic field itself, can cause joint angle non-linearity in the measurement of the axial rotation angle by the angle feedback element, i.e., where h represents the rotation angle θ measured by the joint angle feedback elementkAnd (4) carrying out nonlinear calibration on the joint angle to obtain a nonlinear mapping function h according to a nonlinear function between the true joint angle and the true joint angle.
The embodiment of the invention provides a technical scheme, which can effectively and simultaneously calibrate the axial direction of the joint angle and the nonlinearity of the joint angle.
FIG. 2 shows a schematic flow diagram of a method 200 for multi-joint mechanism calibration according to an embodiment of the invention. The multi-joint mechanism calibrated by the method 200 comprises n joints.
210, individually rotating the mth joint of the multi-joint mechanism.
In the embodiment of the invention, when the multi-joint mechanism is calibrated, a mode of independently rotating each joint is adopted, namely, when the mth joint is calibrated, the mth joint is independently rotated, and other joints are static. n and m are positive integers, and m is more than or equal to 1 and less than or equal to n.
Optionally, the n joints of the multi-joint mechanism are not coupled to each other. Thus, the mth joint can be calibrated by using the measurement data obtained by independently rotating the mth joint.
Optionally, in one embodiment of the invention, upon rotating the mth joint alone, the other joints of the multi-joint mechanism are stationary and the joint angle is set to 0.
Specifically, in order to further reduce the calculation complexity, when the mth joint is rotated alone, the other joints of the multi-joint mechanism are kept stationary and the joint angle is 0, so that the entire calculation process does not involve data of the other joints, thereby reducing the amount of calculation.
It should be understood that when the mth joint is rotated alone, the joint angles of other joints may not be 0, and the calculation result may be obtained as long as the data of other joints is known data, which is not limited by the embodiment of the present invention.
220, acquiring the joint angle of the mth joint before and after rotating the mth joint, and acquiring the posture of the output end of the multi-joint mechanism before and after rotating the mth joint.
For the m-th joint, the joint angle before and after the rotation thereof and the posture of the output end of the multi-joint mechanism before and after the rotation, that is, the posture of the multi-joint mechanism are acquired.
It will be appreciated that since the joint angle before rotation and the attitude of the multi-joint mechanism may be zero or a known amount, in this case, only the data after rotation need be measured.
Optionally, the joint angle of the mth joint may be obtained by an angle feedback element, wherein the angle feedback element is disposed at the mth joint, and the angle feedback element is used for measuring the joint angle of the mth joint.
The angle feedback element may be disposed at a joint, for example, at an electrode of the joint, and may measure a joint angle of the corresponding joint, thereby obtaining a rotation angle (rotation angle) of the joint.
In embodiments of the present invention, the angle feedback element may be any of a variety of elements capable of measuring joint angle, such as: hall elements, photoelectric encoding devices, and the like, but the present invention is not limited thereto.
Alternatively, the attitude of the output end may be acquired by an attitude measuring element.
In the embodiment of the present invention, the attitude measurement element may be various elements capable of measuring an attitude, such as: the attitude measurement element may include at least one of an inertial measurement element, a Micro-Mechanical gyroscope, a Micro-Electro-Mechanical System (MEMS) device, or a visual sensor, which is not limited in this embodiment of the present invention. The attitude measurement element may be provided in the articulated mechanism (for example, an inertial measurement element, a micro-mechanical gyroscope, a MEMS device, or the like), or may not be provided in the articulated mechanism (for example, a visual sensor or the like), which is not limited in the embodiment of the present invention.
230, calibrating the joint angle nonlinearity of the angle feedback element at the mth joint and the axial direction of the rotating shaft of the mth joint according to the joint angle of the mth joint before and after rotating the mth joint and the posture of the output end.
In the embodiment of the invention, the joint angle nonlinearity of the angle feedback element at the mth joint and the axial direction of the rotating shaft of the mth joint are calibrated according to the measurement data before and after the mth joint is independently rotated.
Specifically, an axial vector of a rotating shaft of the mth joint and a rotation angle of the mth joint may be determined according to postures of the output end before and after the mth joint is rotated; and determining a nonlinear function of the angle feedback element at the mth joint according to the rotation angle of the mth joint and joint angles of the mth joint before and after the mth joint is rotated, wherein the nonlinear function represents a nonlinear function between a measured value and a real value of the joint angle of the mth joint.
The pose of the output under the global coordinate system can be expressed as:
wherein R iss(0) Representing the attitude of the output when all joint angles are at zero, and e represents an exponential operation of the matrix, representing a rotation along axis ω by angle θ, representing an antisymmetric matrix of the elements of ω.
Obtaining attitude R of output end by attitude measuring elementsThen the measured attitude change Rs(0)TRs(t) is then:
in the embodiment of the invention, the calibration of each joint angle is decoupled by independently rotating the mth joint, so that the operation amount of a calibration algorithm is simplified, and the nonlinearity of the axial direction and the joint angle is calibrated simultaneously.
When the mth joint rotates alone, and the other joints are stationary and the joint angle is set to 0, it can be obtained from equation (2):
where log represents the logarithmic mapping of the matrix, then it can be obtained from equation (3):
ωm＝ζm (5)
wherein, the rotation angle is represented, the rotation axis vector of the rotation is represented, and s represents the designated rotation direction (only including positive and negative).
According to the posture variation R of the front and rear output ends of the mth joints(0)TRs(t), the axial vector ω of the rotation shaft of the mth joint can be obtained by using the formula (5)kAnd further the calibration in the axial direction can be realized.
According to the posture variation R of the front and rear output ends of the mth joints(0)TRs(t), the nonlinear function h (θ) of the angle feedback element at the mth joint can be obtained using equation (4)m) And further, the nonlinear calibration of the joint angle can be realized.
Alternatively, the non-linear function may be determined from a plurality of sets of measurement data obtained from a plurality of individual rotations of the mth joint.
For example, toIn a non-linear function h (theta)m) The spline function or other parameterization method can be selected, and after the k groups of measurement data are obtained, the k groups of measurement data are obtained by the formula (4). For example, the nonlinear function h (θ) can be obtained by the least square methodm) As shown in fig. 3.
Alternatively, the axial vector of the rotation shaft of the mth joint may be determined from a plurality of sets of measurement data, where the plurality of sets of measurement data are obtained by individually rotating the mth joint a plurality of times.
That is, for axial vector ωkAnd can also be determined from the k sets of measurement data. For example, it can be determined according to the following formula:
according to the technical scheme of the embodiment of the invention, the mth joint is independently rotated, the joint angle nonlinearity of the angle feedback element at the mth joint and the axial direction of the rotating shaft of the mth joint are calibrated according to the joint angle of the mth joint before and after the mth joint is rotated and the posture of the output end of the multi-joint mechanism, the axial direction and the joint angle nonlinearity can be simultaneously calibrated with a small calculated amount, and the calibration efficiency of the multi-joint mechanism can be improved.
Optionally, in an embodiment of the present invention, when there is a zero offset error in the attitude measurement element that acquires the attitude of the output end, zero offset error compensation may be performed on the attitude measurement element.
Some attitude measurement components may have zero offset error. For example, taking a MEMS gyroscope as an example, when the MEMS gyroscope is selected, the attitude change amount R can be obtained as an angular rate of the relative inertial system in real times(0)TRs(t) can be reduced to the integral of angular rate, i.e. so as to obtain a sum ζm：
The subsequent calculation can be performed by bringing (7) and (8) into the formulas (4) and (5).
However, the output of the MEMS device may have zero offset error, i.e.:
wherein the measured value, ΩsRepresenting the true angular rate and b the zero offset error.
Zero bias errors accumulate over time causing drift in the integral:
the items therein may cause the provided pose to deviate from the true pose
In the embodiment of the invention, the zero offset error is compensated. Alternatively, the zero offset error compensation can be performed in the following manner:
determining a zero offset error between a first time and a second time during the rotation of the mth joint independently from measurement data of the attitude measurement element at the first time and the second time, wherein the measured joint angles of the mth joint of the angle feedback element at the mth joint are the same at the first time and the second time;
and compensating the zero offset error according to the zero offset error between the first time and the second time.
Specifically, the angle feedback element of the joint angle has a non-linear error, but the error does not accumulate with the increase of time. Thus, when calibrating the mth joint, t will be1The reading value of the mth joint angle feedback element at the moment is recorded as t2The reading value of the moment is recorded as that if the reading value exists, the joint angle passes through a closed loop, and the posture variation is 0, namely Rs(t1)TRs(t2) If a MEMS device is chosen, it can be represented as a substitution (10) available in a closed loop process, i.e. t1To t2In the time period, the integral result of the output value of the MEMS is equal to the drift value of the zero offset error accumulated along with the time, and then the zero offset error is obtained as follows:
according to the zero offset error obtained by the formula (11), corresponding zero offset error compensation can be carried out.
FIG. 4 is a schematic diagram of the reciprocating rotational trajectory of a multi-joint structure according to an embodiment of the present invention. The track of fig. 4 can be used for compensation of zero offset errors. In fig. 4, three motions in X, Y, and Z axes are taken as an example, and correspond to three joints. As shown in FIG. 4, for each joint, the measured angle θ of the angle feedback element may be basedkFinding out corresponding points, wherein the two points are two corresponding points which can form a closed loop, and the cross line between the two pointsThe difference of the coordinates is the integration time. The integral value of the MEMS in the integration time is equal to zero offset error
Fig. 5 can be obtained by setting the time difference between two points that can form a closed section in fig. 4 as the abscissa. In fig. 5, the zero offset compensation value is obtained by linear fitting according to the zero offset error. As shown in fig. 5, under the condition that the closed interval is formed, the compensated MEMS integral value is substantially 0, which is in accordance with the fact that the attitude change is 0, and thus it can be seen that the method has a good zero offset error compensation effect.
In the embodiment of the invention, the calibration of the multi-joint structure can be more accurate through the zero offset error compensation.
The method for calibrating the multi-joint mechanism according to the embodiment of the invention is described above in detail, and the device and the computer system for calibrating the multi-joint mechanism according to the embodiment of the invention are described below. It should be understood that the apparatus for calibrating a multi-joint mechanism and the computer system according to the embodiments of the present invention may perform the methods according to the embodiments of the present invention, that is, the following specific working processes of various products may refer to the corresponding processes in the embodiments of the foregoing methods, and therefore, for brevity, no further description is provided.
Fig. 6 shows a schematic block diagram of an apparatus 600 for multi-joint mechanism calibration according to an embodiment of the present invention. The device 600 may perform the method for calibrating a multi-joint mechanism according to the embodiment of the present invention, and calibrate the multi-joint mechanism including n joints.
As shown in fig. 6, the apparatus 600 may include:
the rotation control module 610 is configured to separately rotate an mth joint of the multi-joint mechanism, where an angle feedback element is disposed at the mth joint, the angle feedback element is configured to measure a joint angle of the mth joint, n and m are positive integers, and m is greater than or equal to 1 and less than or equal to n;
an obtaining module 620, configured to obtain joint angles of the mth joint before and after the mth joint is rotated, and obtain a posture of an output end of the multi-joint mechanism before and after the mth joint is rotated;
a calibration module 630, configured to calibrate joint angle nonlinearity of the angle feedback element at the mth joint and an axial direction of a rotation shaft of the mth joint according to a joint angle of the mth joint before and after the mth joint is rotated and a posture of the output end.
Optionally, the angle feedback element comprises a hall element or an opto-electronic encoding device.
Optionally, the obtaining module 620 is specifically configured to:
and acquiring the attitude of the output end through an attitude measuring element.
Optionally, the attitude measurement element comprises at least one of an inertial measurement element, a micromechanical gyroscope, a microelectromechanical system MEMS device, or a visual sensor.
Optionally, the n joints are not coupled to each other.
Optionally, the rotation control module 610 is configured to control other joints of the multi-joint mechanism to be stationary and to have a joint angle of 0 when the mth joint is rotated alone.
Optionally, the calibration module 630 is specifically configured to:
determining an axial vector of a rotating shaft of the mth joint and a rotating angle of the mth joint according to the postures of the output ends before and after the mth joint is rotated;
determining a non-linear function of the angle feedback element at the mth joint according to the rotation angle of the mth joint and joint angles of the mth joint before and after rotating the mth joint, wherein the non-linear function represents a non-linear function between a measured value and a real value of the joint angle of the mth joint.
Optionally, the calibration module 630 is specifically configured to:
determining the non-linear function from a plurality of sets of measurement data, wherein the plurality of sets of measurement data are obtained from a plurality of individual rotations of the mth joint.
Optionally, the calibration module 630 is specifically configured to:
and determining the nonlinear function by a least square method according to the plurality of groups of measurement data.
Optionally, the calibration module 630 is specifically configured to:
and determining the axial vector of the rotating shaft of the mth joint according to multiple sets of measurement data, wherein the multiple sets of measurement data are obtained by independently rotating the mth joint for multiple times.
Optionally, as shown in fig. 7, the apparatus 600 further includes:
and the zero offset error compensation module 640 is configured to perform zero offset error compensation on the attitude measurement element that acquires the attitude of the output end when the attitude measurement element has a zero offset error.
Optionally, the zero offset error compensation module 640 is specifically configured to:
determining a zero offset error between a first time and a second time during the rotation of the mth joint independently from measurement data of the attitude measurement element at the first time and the second time, wherein the measured joint angles of the mth joint of the angle feedback element at the mth joint are the same at the first time and the second time;
and compensating the zero offset error according to the zero offset error between the first time and the second time.
It should be understood that the device for calibrating the multi-joint mechanism according to the above embodiment of the present invention may be a chip, which may be specifically implemented by a circuit, and a processor may use the chip, but the embodiment of the present invention is not limited to a specific implementation form. In addition, the device for calibrating the multi-joint mechanism in the embodiment of the invention can be arranged in the multi-joint mechanism or can be a device outside the multi-joint mechanism.
FIG. 8 shows a schematic block diagram of a computer system 800 of one embodiment of the present invention.
As shown in fig. 8, the computer system 800 may include a processor 810 and a memory 820.
It should be understood that other components commonly included in computer systems, such as communication interfaces, etc., may also be included in computer system 800, and embodiments of the present invention are not limited thereto.
The memory 820 is used to store computer executable instructions.
The Memory 820 may be various types of memories, and may include a Random Access Memory (RAM) and a non-volatile Memory (non-volatile Memory), such as at least one disk Memory, for example, which is not limited in this embodiment of the present invention.
The processor 810 is configured to access the memory 820 and execute the computer-executable instructions to perform the operations in the methods of the various embodiments of the present invention described above.
The processor 810 may include a microprocessor, a Field-Programmable Gate Array (FPGA), a Central Processing Unit (CPU), a Graphics Processing Unit (GPU), and the like, which are not limited in the embodiments of the present invention.
In one embodiment, the multi-joint mechanism of embodiments of the present invention may include the computer system 800 to perform the operations described above in the methods of various embodiments of the present invention.
The embodiment of the invention also provides a movable device, which can comprise the device for calibrating the multi-joint mechanism or the computer system in the various embodiments of the invention.
The device for calibrating a multi-joint mechanism, the computer system, the multi-joint mechanism and the mobile device in the embodiment of the present invention may correspond to an execution main body of the method for calibrating a multi-joint mechanism in the embodiment of the present invention, and the above and other operations and/or functions of each module in the device for calibrating a multi-joint mechanism, the computer system, the multi-joint mechanism and the mobile device are respectively for implementing corresponding processes of each method, and are not described herein again for brevity.
Embodiments of the present invention also provide a computer storage medium having a program code stored therein, where the program code may be used to instruct a method for performing image processing according to the above-described embodiments of the present invention.
It should be understood that, in the embodiment of the present invention, the term "and/or" is only one kind of association relation describing an associated object, and means that three kinds of relations may exist. For example, a and/or B, may represent: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" herein generally indicates that the former and latter related objects are in an "or" relationship.
Those of ordinary skill in the art will appreciate that the elements and algorithm steps of the examples described in connection with the embodiments disclosed herein may be embodied in electronic hardware, computer software, or combinations of both, and that the components and steps of the examples have been described in a functional general in the foregoing description for the purpose of illustrating clearly the interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
It is clear to those skilled in the art that, for convenience and brevity of description, the specific working processes of the above-described systems, apparatuses and units may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may also be an electric, mechanical or other form of connection.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment of the present invention.
In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.
The integrated unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present invention essentially or partially contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product stored in a storage medium and including instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: various media capable of storing program codes, such as a usb disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk, or an optical disk.
While the invention has been described with reference to specific embodiments, the invention is not limited thereto, and various equivalent modifications and substitutions can be easily made by those skilled in the art within the technical scope of the invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (25)
- A method of multi-joint mechanism calibration, wherein the multi-joint mechanism comprises n joints, the method comprising:independently rotating the mth joint of the multi-joint mechanism, wherein an angle feedback element is arranged at the mth joint and used for measuring the joint angle of the mth joint, n and m are positive integers, and m is greater than or equal to 1 and less than or equal to n;acquiring joint angles of the mth joint before and after the mth joint is rotated, and acquiring a posture of an output end of the multi-joint mechanism before and after the mth joint is rotated;and calibrating the joint angle nonlinearity of the angle feedback element at the mth joint and the axial direction of the rotating shaft of the mth joint according to the joint angle of the mth joint before and after the mth joint is rotated and the posture of the output end.
- The method of claim 1, wherein the angular feedback element comprises a hall element or an opto-electronic encoder device.
- The method of claim 1, wherein the obtaining the pose of the output of the multi-joint mechanism before and after rotating the mth joint comprises:and acquiring the attitude of the output end through an attitude measuring element.
- The method of claim 3, wherein the attitude measurement component comprises at least one of an inertial measurement component, a micromechanical gyroscope, a microelectromechanical system (MEMS) device, or a visual sensor.
- The method of any one of claims 1 to 4, wherein the n joints are not coupled to each other.
- The method according to any one of claims 1 to 4, wherein upon rotating the mth joint alone, the other joints of the multi-joint mechanism are stationary and the joint angle is set to 0.
- The method of any one of claims 1 to 4, wherein the calibrating the joint angle nonlinearity of the angle feedback element at the mth joint and the axial direction of the rotation axis of the mth joint comprises:determining an axial vector of a rotating shaft of the mth joint and a rotating angle of the mth joint according to the postures of the output ends before and after the mth joint is rotated;determining a non-linear function of the angle feedback element at the mth joint according to the rotation angle of the mth joint and joint angles of the mth joint before and after rotating the mth joint, wherein the non-linear function represents a non-linear function between a measured value and a real value of the joint angle of the mth joint.
- The method of claim 7, wherein said determining a non-linear function of said angular feedback element at said mth joint comprises:determining the non-linear function from a plurality of sets of measurement data, wherein the plurality of sets of measurement data are obtained from a plurality of individual rotations of the mth joint.
- The method of claim 8, wherein determining the non-linear function from the plurality of sets of measurement data comprises:and determining the nonlinear function by a least square method according to the plurality of groups of measurement data.
- The method of claim 7, wherein said determining an axial vector of an axis of rotation of said mth joint comprises:and determining the axial vector of the rotating shaft of the mth joint according to multiple sets of measurement data, wherein the multiple sets of measurement data are obtained by independently rotating the mth joint for multiple times.
- The method according to any one of claims 1 to 4, further comprising:and when the attitude measurement element for acquiring the attitude of the output end has zero offset error, performing zero offset error compensation on the attitude measurement element.
- The method of claim 11, wherein the compensating the attitude measurement component for zero offset error comprises:determining a zero offset error between a first time and a second time during the rotation of the mth joint independently from measurement data of the attitude measurement element at the first time and the second time, wherein the measured joint angles of the mth joint of the angle feedback element at the mth joint are the same at the first time and the second time;and compensating the zero offset error according to the zero offset error between the first time and the second time.
- An apparatus for calibrating a multi-joint mechanism, wherein the multi-joint mechanism comprises n joints, the apparatus comprising:the rotation control module is used for independently rotating the mth joint of the multi-joint mechanism, wherein an angle feedback element is arranged at the mth joint and used for measuring the joint angle of the mth joint, n and m are positive integers, and m is greater than or equal to 1 and less than or equal to n;an acquisition module configured to acquire joint angles of the mth joint before and after the mth joint is rotated, and acquire a posture of an output end of the multi-joint mechanism before and after the mth joint is rotated;and the calibration module is used for calibrating the joint angle nonlinearity of the angle feedback element at the mth joint and the axial direction of the rotating shaft of the mth joint according to the joint angle of the mth joint before and after the mth joint is rotated and the posture of the output end.
- The apparatus of claim 13, wherein the angular feedback element comprises a hall element or an opto-electronic encoder device.
- The apparatus of claim 13, wherein the obtaining module is specifically configured to:and acquiring the attitude of the output end through an attitude measuring element.
- The apparatus of claim 15, wherein the attitude measurement component comprises at least one of an inertial measurement component, a micromechanical gyroscope, a microelectromechanical system (MEMS) device, or a vision sensor.
- The apparatus of any one of claims 13 to 16, wherein the n joints are not coupled to each other.
- The apparatus of any one of claims 13 to 16, wherein the rotation control module is configured to control the other joints of the multi-joint mechanism to be stationary and to have a joint angle of 0 when the mth joint is rotated alone.
- The apparatus according to any one of claims 13 to 16, wherein the calibration module is specifically configured to:determining an axial vector of a rotating shaft of the mth joint and a rotating angle of the mth joint according to the postures of the output ends before and after the mth joint is rotated;determining a non-linear function of the angle feedback element at the mth joint according to the rotation angle of the mth joint and joint angles of the mth joint before and after rotating the mth joint, wherein the non-linear function represents a non-linear function between a measured value and a real value of the joint angle of the mth joint.
- The apparatus of claim 19, wherein the calibration module is specifically configured to:determining the non-linear function from a plurality of sets of measurement data, wherein the plurality of sets of measurement data are obtained from a plurality of individual rotations of the mth joint.
- The apparatus of claim 20, wherein the calibration module is specifically configured to:and determining the nonlinear function by a least square method according to the plurality of groups of measurement data.
- The apparatus of claim 19, wherein the calibration module is specifically configured to:and determining the axial vector of the rotating shaft of the mth joint according to multiple sets of measurement data, wherein the multiple sets of measurement data are obtained by independently rotating the mth joint for multiple times.
- The apparatus of any one of claims 13 to 16, further comprising:and the zero offset error compensation module is used for compensating the zero offset error of the attitude measurement element when the attitude measurement element for acquiring the attitude of the output end has the zero offset error.
- The apparatus of claim 23, wherein the zero offset error compensation module is specifically configured to:determining a zero offset error between a first time and a second time during the rotation of the mth joint independently from measurement data of the attitude measurement element at the first time and the second time, wherein the measured joint angles of the mth joint of the angle feedback element at the mth joint are the same at the first time and the second time;and compensating the zero offset error according to the zero offset error between the first time and the second time.
- A computer system, comprising:a memory for storing computer executable instructions;a processor for accessing the memory and executing the computer-executable instructions to perform operations in the method of any one of claims 1 to 12.
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