WO2018145647A1

WO2018145647A1 - Calibration method for magnetic encoder and system

Info

Publication number: WO2018145647A1
Application number: PCT/CN2018/075863
Authority: WO
Inventors: 胡华智; 胡海生
Original assignee: 亿航智能设备（广州）有限公司
Priority date: 2017-02-08
Filing date: 2018-02-08
Publication date: 2018-08-16
Also published as: CN106679710A; CN106679710B

Abstract

A calibration method for a magnetic encoder and a system, which relate to the technical field of motor control, the method comprising: driving a motor (30) by means of an electric adjusting board (20) to rotate step-wise by using a preset electric angle; acquiring encoder data of each step point; performing linearization calibration on the encoder data by using a linear interpolation method to obtain linearized data of a mechanical angle, which may improve the calibration efficiency and accuracy of the magnetic encoder.

Description

Magnetic encoder calibration method and system

Technical field

The present invention relates to the field of motor control technologies, and in particular, to a magnetic encoder calibration method and system.

Background technique

An encoder is a device that converts electrical signals or data into a form that can be used for communication, transmission, and storage. The encoder can be further classified into a photoelectric encoder and a magnetic encoder according to its own properties. The magnetic encoder is a new type of angle or displacement measuring device. The principle is to measure the angle or displacement value of the changed magnetic material by magnetoresistive or Hall element. The change of the angle or displacement of the magnetic material will cause a certain resistance or voltage. The change is amplified by the amplifying circuit, and the pulse signal or analog signal is outputted by the single-chip microcomputer to achieve the purpose of measurement. Due to the influence of many non-ideal factors, the output of the magnetic encoder often has errors. The adjustment will inevitably result in a large demodulation error, which needs to be calibrated first. The existing calibration method generally adopts a model-based off-line calibration method with low efficiency and low accuracy.

technical problem

The main object of the present invention is to provide a magnetic encoder calibration method and system, which can improve the calibration efficiency and accuracy of the magnetic encoder.

Technical solution

To achieve the above object, a magnetic encoder calibration method provided by the present invention includes:

Driving the motor through the ESC to rotate at a preset electrical angle;

Collect encoder data for each step point;

The encoder data is linearly calibrated using linear interpolation to obtain linearized mechanical angle data.

Optionally, the collecting the encoder data of each step point comprises:

Calculating a driving signal of the motor according to the preset electrical angle;

The driving signal is sequentially outputted to the motor, so that the motor rotates one revolution according to a mechanical angle, and encoder data of each step point in the process of rotating the motor is acquired.

Optionally, the driving signal includes an initial position driving signal, and an initial position driving signal is output to the motor through the ESC, the motor is rotated to an initial position, and the mechanical angle data at the time is collected, and according to the mechanical angle data. Get the electrical angle offset.

Optionally, the linearly calibrating the encoder data by linear interpolation to obtain linearized mechanical angle data further includes:

Performing calibration verification on the encoder data, determining whether the encoder data of each step point is incremented, and whether the difference between the encoder data of the adjacent step points is within a preset threshold, and if so, verifying success.

Optionally, the ESC board includes a yaw electric adjustment board, a horizontal rotation adjustment board, and a pitch electric adjustment board, respectively, for controlling the yaw motor, the roll motor, and the motor, and each of the motors is provided with an encoder. .

As another aspect of the present invention, a magnetic encoder calibration system includes a host computer and a servo motor system, and the servo motor system includes an electric adjustment board and a motor, wherein

The ESC is configured to drive the motor to rotate in a preset electrical angle; acquire encoder data of each step point; linearly calibrate the encoder data by linear interpolation to obtain linearization Mechanical angle data;

The upper computer is configured to interact with an electrical regulation board.

Optionally, the collecting the encoder data of each step point comprises:

Optionally, the upper computer is further configured to:

Beneficial effect

A method and system for calibrating a magnetic encoder according to the present invention includes: driving a motor through a preset plate at a preset electrical angle; acquiring encoder data of each step point; using linear interpolation The encoder data is linearly calibrated to obtain linearized mechanical angle data, which can improve the calibration efficiency and accuracy of the magnetic encoder.

DRAWINGS

1 is a flowchart of a magnetic encoder calibration method according to Embodiment 1 of the present invention;

FIG. 2 is a block diagram showing an exemplary structure of a magnetic encoder calibration system according to Embodiment 2 of the present invention.

The implementation, functional features, and advantages of the present invention will be further described in conjunction with the embodiments.

Embodiments of the invention

It is understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

In the following description, the use of suffixes such as "module", "component" or "unit" for indicating an element is merely an explanation for facilitating the present invention, and does not have a specific meaning per se. Therefore, "module" and "component" can be used in combination.

Embodiment 1

As shown in FIG. 1, in this embodiment, a magnetic encoder calibration method includes:

S10, driving the motor through the ESC to rotate at a preset electrical angle;

S20. Collect encoder data of each step point;

S30. Perform linearization calibration on the encoder data by linear interpolation to obtain linearized mechanical angle data.

In this embodiment, the calibration method can be automatically performed, and each motor and the ESC can be separately calibrated to improve the calibration efficiency and accuracy of the magnetic encoder.

In this embodiment, the ESC is connected to the host computer through a Controller Area Network (CAN) bus.

In this embodiment, the upper computer is configured to send an electrical angle calibration command, a verification command, and the like to the ESC, and receive a success signal, a failure signal, and other interaction signals returned by the ESC.

In this embodiment, the ESC includes a yaw yaw, a roll ESC roll, and a pitch ESC pitch for controlling a yaw motor, a roll motor, and a motor, respectively. There is an encoder set.

In this embodiment, the method is used in the production line step. At this time, the ESC and the motor are completely installed, the PTZ is not completely assembled, and the motor rotation motion is not limited by the position of the PTZ to the motor, and the motor can rotate freely. In one lap, the yaw, roll, and pitch ESCs are connected via the CAN bus and connected to the PC host computer with the USBCAN switch.

In this embodiment, the preset electrical angle is an electrical angle value set by the system according to calibration accuracy or user requirements, such as 60°, 90°, or 120°, etc., which is convenient for calculation, and the electrical angle is 60. ° For example, the motor can be rotated 60° every step, and it can be rotated one turn according to the electrical angle.

In this embodiment, the angle 360°/p occupied by each pair of poles on the inner circle of the stator refers to the actual spatial geometric angle, which is called the mechanical angle; the number of poles at the quadrupole and above (p≥ 4) The motor usually defines the mechanical angle of a pair of poles as 360 degrees of electrical angle, because the induced potential change in the winding is 360° for one cycle; for the two-pole motor, the electrical angle of the stator inner circle and the mechanical angle The angles are equal to 360°; for the p-pole motor, the electrical angle of the stator inner circle is 360°*p, but the mechanical angle is still 360°, so the two have the following relationship:

Electrical angle = mechanical angle × pole pair

In the present embodiment, the number of pole pairs of the stator is four pairs, and the relationship between the electrical angle and the mechanical angle is four times.

As another embodiment, the number of pole pairs of the stator may also be other numbers, which can be calibrated by the method.

In this embodiment, the step S20 includes:

In this embodiment, the driving signal includes an initial position driving signal, and an initial position driving signal is output to the motor through the ESC, and the motor is rotated to an initial position, and the mechanical angle data at this time is collected, and according to the mechanical The angle data obtains the electrical angle zero offset.

In this embodiment, the host computer sends an electrical angle calibration command through the CAN bus, and after receiving the calibration command, the ESC closes the servo control loop, including the angle loop, the speed loop, the current loop, and the space vector pulse width modulation (Space). Vector Pulse Width Modulation) SVPWM unit, switching from SVPWM mode to pulse width modulation (Pulse Width) Modulation) PWM mode, the ESC sends a motor (0, T, T) signal to the motor to an electrical angle of -180°, where the (0, T, T) signal is the initial position drive signal, (0, The T, T) signal indicates that one of the three-phase motors is not energized (indicated by 0), the other two phases are energized (indicated by T), and the motor is locked by the degree of change in the encoder data, if the motor is locked Dead, indicating that the motor has reached the stepping point according to the driving signal, record the mechanical angle data given by the encoder at this time, until the motor completes the linear calibration and returns to the calibration starting point, comparing the mechanical angle data of the starting point and the ending point, if The phase difference is within the threshold, and it is determined that the calibration is successful. At this time, the linearized mechanical angle is converted into an electrical angle and added to -180°, and written into FALSH as an electrical angle zero offset.

After performing the above electrical angle calibration step, the following (0, T, T), (0, 0, T), (T, 0, T), (T, 0, 0), (T, T) are sequentially output to the motor. , 0), (0, T, 0), the drive motor is stepped in the positive direction of the electrical angle, and each step further determines whether the motor has reached the step point through the encoder data until the motor has reached the step point, and then outputs One step PWM signal continues to drive the motor forward, the step angle is 60°, and the encoder data at the stepping point is recorded in turn until the motor rotates the mechanical angle one turn and is written into RAM and FALSH for linearization. The processing is used, and finally the end signal is returned to the upper machine.

In this embodiment, the data collected by the encoder is mechanical angle data. When the electrical angle is rotated by 60°, according to the conversion relationship between the electrical angle and the mechanical angle, the mechanical angle of the motor is rotated by 15°. The method is to calibrate by collecting the encoder data of each step point in the process of rotating the motor according to the mechanical angle. Therefore, it is necessary to rotate the motor 4 times according to the electrical angle, and a total of 24 mechanical angle data are collected, due to numerous These mechanical angle data are nonlinear in the influence of non-ideal factors, which requires linearization of these mechanical angle data.

As another embodiment, when the preset electrical angle is 90°, the number of driving signals is four, and the specific algorithm is prior art, and details are not described herein.

In the present embodiment, the linearization calibration uses a linear interpolation method, using the actual electrical angle as a reference point, linearly interpolating the original mechanical angle of the encoder, outputting the linearized mechanical angle data, and linearizing the mechanical angle. Multiply the pole log p into an electrical angle unit and subtract the electrical angle to obtain the electrical angle. Finally, the output is used by the SVPWM module. The linearized mechanical angle minus the mechanical angle zero-bias output mechanical angle gives the servo loop position servo control or output to the attitude loop for attitude decoupling control.

In this embodiment, before the step S30, the method further includes:

Performing calibration verification on the encoder data, determining whether the encoder data of each step point is incremented, and whether the difference between the encoder data of the adjacent step points is within a preset threshold, and if so, verifying Successfully, the ESC returns a success signal to the upper computer. If the condition is not met, the failure signal is returned. The purpose of the calibration verification step is to eliminate the calibration failure. When the calibration process has external force to hinder the motor movement, or due to the motor itself, for example. One of the three phase lines is open, which will cause the calibration to fail.

Embodiment 2

As shown in FIG. 2, in the embodiment, a magnetic encoder calibration system includes a host computer 10 and a servo motor system, and the servo motor system includes an electric adjustment board 20 and a motor 30, wherein

Electrical angle = mechanical angle × pole pair

In this embodiment, the collecting encoder data of each step point includes:

In this embodiment, the host computer sends an electrical angle calibration command through the CAN bus, and after receiving the calibration command, the motor board turns off the servo control loop, including the angle loop, the speed loop, the current loop, and the space vector pulse width modulation (Space Vector Pulse Width Modulation) SVPWM unit, switching from SVPWM mode to pulse width modulation (Pulse Width) Modulation) PWM mode, the ESC sends a motor (0, T, T) signal to the motor to an electrical angle of -180°, where the (0, T, T) signal is the initial position drive signal, (0, The T, T) signal indicates that one of the three-phase motors is not energized (indicated by 0), the other two phases are energized (indicated by T), and the motor is locked by the degree of change in the encoder data, if the motor is locked Dead, indicating that the motor has reached the stepping point according to the driving signal, record the mechanical angle data given by the encoder at this time, until the motor completes the linear calibration and returns to the calibration starting point, comparing the mechanical angle data of the starting point and the ending point, if The phase difference is within the threshold, and it is determined that the calibration is successful. At this time, the linearized mechanical angle is converted into an electrical angle and added to -180°, and written into FALSH as an electrical angle zero offset.

In this embodiment, the upper computer is further configured to:

Performing calibration verification on the encoder data, determining whether the encoder data of each step point is incremented, and whether the difference between the encoder data of the adjacent step points is within a preset threshold, and if so, verifying Successfully, the motor board returns a success signal to the upper machine. If the condition is not met, the failure signal is returned. The purpose of the calibration verification step is to eliminate the calibration failure. When the calibration process has external force to hinder the motor movement, or due to the motor itself, such as three A phase line break in the phase line will cause the calibration to fail.

It is to be understood that the term "comprises", "comprising", or any other variants thereof, is intended to encompass a non-exclusive inclusion, such that a process, method, article, or device comprising a series of elements includes those elements. It also includes other elements that are not explicitly listed, or elements that are inherent to such a process, method, article, or device. An element that is defined by the phrase "comprising a ..." does not exclude the presence of additional equivalent elements in the process, method, item, or device that comprises the element.

The serial numbers of the embodiments of the present invention are merely for the description, and do not represent the advantages and disadvantages of the embodiments.

Through the description of the above embodiments, those skilled in the art can clearly understand that the foregoing embodiment method can be implemented by means of software plus a necessary general hardware platform, and of course, can also be through hardware, but in many cases, the former is better. Implementation. Based on such understanding, the technical solution of the present invention, which is essential or contributes to the prior art, may be embodied in the form of a software product stored in a storage medium (such as ROM/RAM, disk, The optical disc includes a number of instructions for causing a terminal device (which may be a cell phone, a computer, a server, an air conditioner, or a network device, etc.) to perform the methods described in various embodiments of the present invention.

The above are only the preferred embodiments of the present invention, and are not intended to limit the scope of the invention, and the equivalent structure or equivalent process transformations made by the description of the present invention and the drawings are directly or indirectly applied to other related technical fields. The same is included in the scope of patent protection of the present invention.

Industrial applicability

The magnetic encoder calibration method and system provided by the invention are driven by a motor to drive the motor to rotate at a preset electrical angle; the encoder data of each step point is collected; and the encoder data is linearly interpolated. Linear calibration is performed to obtain linearized mechanical angle data, which can improve the calibration efficiency and accuracy of the magnetic encoder. Therefore, it has industrial applicability.

Claims

A magnetic encoder calibration method comprising:

Driving the motor through the ESC to rotate at a preset electrical angle;

Collect encoder data for each step point;

The encoder data is linearly calibrated using linear interpolation to obtain linearized mechanical angle data.
A magnetic encoder calibration method according to claim 1, wherein said acquiring encoder data for each step point comprises:

Calculating a driving signal of the motor according to the preset electrical angle;

The driving signal is sequentially outputted to the motor, so that the motor rotates one revolution according to a mechanical angle, and encoder data of each step point in the process of rotating the motor is acquired.
The magnetic encoder calibration method according to claim 2, wherein the driving signal comprises an initial position driving signal, and an initial position driving signal is output to the motor through the ESC, and the motor is rotated to an initial position, and the driving is performed. The mechanical angle data of the time, and the electrical angle zero offset is obtained according to the mechanical angle data.
A magnetic encoder calibration method according to claim 2, wherein said linearly calibrating said encoder data by linear interpolation to obtain linearized mechanical angle data further comprises:

Performing calibration verification on the encoder data, determining whether the encoder data of each step point is incremented, and whether the difference between the encoder data of the adjacent step points is within a preset threshold, and if so, verifying success.
A magnetic encoder calibration method according to claim 1, wherein said ESC includes a yaw electric adjustment plate, a roll adjustment plate and a pitch adjustment plate for controlling a yaw motor and a roll Motor and motor, one encoder is set on each motor.
A magnetic encoder calibration system includes a host computer and a servo motor system, and the servo motor system includes an electric adjustment board and a motor, wherein

The ESC is configured to drive the motor to rotate in a preset electrical angle; acquire encoder data of each step point; linearly calibrate the encoder data by linear interpolation to obtain linearization Mechanical angle data;

The upper computer is configured to interact with an electrical regulation board.
A magnetic encoder calibration system according to claim 6 wherein said acquiring encoder data for each step point comprises:

Calculating a driving signal of the motor according to the preset electrical angle;

The driving signal is sequentially outputted to the motor, so that the motor rotates one revolution according to a mechanical angle, and encoder data of each step point in the process of rotating the motor is acquired.
A magnetic encoder calibration system according to claim 7, wherein said driving signal comprises an initial position driving signal, and an initial position driving signal is output to the motor through the ESC, and the motor is rotated to an initial position, and the driving is performed. The mechanical angle data of the time, and the electrical angle zero offset is obtained according to the mechanical angle data.
A magnetic encoder calibration system according to claim 7, wherein said upper computer is further configured to:

Performing calibration verification on the encoder data, determining whether the encoder data of each step point is incremented, and whether the difference between the encoder data of the adjacent step points is within a preset threshold, and if so, verifying success.
A magnetic encoder calibration system according to claim 6, wherein said ESC includes a yaw electric adjustment plate, a roll adjustment plate and a pitch adjustment plate for controlling a yaw motor and a roll Motor and motor, one encoder is set on each motor.