Dual read head discernible multiple zero point positioning method for electric actuators

Abstract

The present application relates to electric actuator technical field, especially to a kind of double read head distinguishable multiple zero point positioning method for electric actuator, solve the need long stroke operation to calibrate in prior art under extreme state, for this, multiple zero point can solve this problem, but if not distinguished, absolute position cannot be distinguished, multiple angles also restrict the number of zero points distributed on the encoder, with obvious insufficient problem.A kind of double read head distinguishable multiple zero point positioning method for electric actuator, including two zero point detection read heads, and multiple limited types of zero points are uniformly distributed on zero point code track, the combination information of the type of two zero points determines absolute position.The present application realizes the positioning of relatively more different zero points in a circle, and the double read head can cope with the failure of a read head, making the system more reliable.

Description

Technical Field

[0001] This invention relates to the field of electric actuator technology, and in particular to a dual-reader multi-zero point positioning method for electric actuators. Background Technology

[0002] The main advantages of electric actuators are their high stability and the constant thrust applicable to the user. The maximum thrust generated by an electric actuator can reach 225,000 kgf, a figure only achieved by hydraulic actuators, although hydraulic actuators are significantly more expensive. Electric actuators have excellent resistance to deviation, and their output thrust or torque is essentially constant. They can effectively overcome the unbalanced forces of the medium, achieving accurate control of process parameters, thus offering higher control precision than pneumatic actuators. When equipped with a servo amplifier, direct and reverse action can be easily interchanged, and the valve position (hold / fully open / fully closed) can be easily set when the signal is interrupted. In case of a fault, the actuator will remain in its original position, something pneumatic actuators cannot do; pneumatic actuators require a combined protection system to maintain position.

[0003] An electric actuator is an electric device that can be executed to a specific position according to instructions. It mostly adopts a rotary method. With the development of industrial automation, manual operation has been replaced by mechanical or automated equipment. Electric actuators can play the role of interface between the control system and the mechanical movement of valves, and are increasingly used. Electric actuators require long-term stable operation and high positioning accuracy in certain applications. Absolute positioning methods for electric actuators that meet the requirements of long lifespan and high precision typically include absolute photoelectric encoders or photoelectric encoders with zero points. Absolute photoelectric encoders are constrained by the size of the electric actuator, resulting in low positioning resolution and high cost. Photoelectric encoders with zero points offer relatively high accuracy, but require power-on to find the zero point. In common solutions, there is only one zero point per revolution of the code disk, requiring long-stroke operation for calibration in extreme conditions. Multiple zero points can solve this problem, but without differentiation, absolute positions cannot be distinguished. Differentiation of zero points can generally be achieved using zero points at different angles, but multiple angles limit the number of zero points distributed on the code disk, presenting significant shortcomings and inconvenience. Therefore, a dual-reader multi-zero point positioning method for electric actuators is urgently needed to solve these problems. Summary of the Invention

[0004] The purpose of this invention is to provide a dual-reader multi-zero-point positioning method for electric actuators, which solves the problem that in the prior art, long-stroke operation is required for calibration under extreme conditions. The use of multiple zero points can solve this problem, but if they are not distinguished, the absolute position cannot be distinguished. To distinguish the zero points, different angles can generally be used. Multiple zero points require multiple angles, which in turn restricts the number of zero points distributed on the code disk, which has obvious shortcomings.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A dual-reader method for identifying multiple zero points in an electric actuator includes two zero-point detection readers, with multiple zero points of a finite number of types evenly distributed on the zero-point code track. The combination information of the two zero point types determines the absolute position, and multiple distinguishable zero-point positioning is performed. The code disk includes a zero-point code track, and the encoding is a combination of zero points. The combination of zero points is a combination of zero points at the two zero-point detection readers, and also a combination of multiple zero points in the same direction at a single zero-point detection reader. The zero points are evenly distributed, and the center position of each zero point is evenly distributed on the code track.

[0007] Preferably, the zero-point information includes the zero-point type and the zero-point position. The zero-point information is obtained by recording the positions of the rising edge and the falling edge of the reading head during unidirectional movement. The position difference between the rising edge and the falling edge is the angle of the zero point, which can be used to determine the zero-point type. The center point of the rising edge and the falling edge is the position of the zero point.

[0008] Preferably, the rising and falling edges are obtained by comparing the light sensitivity measured by the read head with a specific voltage value through a comparator. When interference is introduced during the edge acquisition process, it will cause incorrect edge triggering, which will generate incorrect zero-point information, which is undesirable for position calibration.

[0009] Preferably, all light sensing values ​​and encoder positions are acquired during the unidirectional movement of the reader. Due to the symmetry of light sensing, the center value of multiple positions with the same light sensing value is obtained, and the center position of the mode is obtained, thereby avoiding position deviation caused by interference and obtaining a more accurate zero-point position. For angle information, since fault tolerance is added in the encoding design, the angles corresponding to various types of zero points are different. In the presence of interference, the acquired angle values ​​will be deviated. By determining which category the angle value is closer to, the zero-point type can be identified.

[0010] Preferably, the process of the two zero-point detection heads reading zero-point information includes the following steps:

[0011] Step 1: When the electric actuator leaves the factory, it will perform one cycle of forward and reverse rotation. During this cycle, the encoder position corresponding to each zero point mark will be calibrated and recorded. In subsequent actual operation, the absolute position of the current zero point can be obtained by looking up the table based on the zero point information. The position of the electric actuator can then be calibrated.

[0012] Step 2: During the operation of the electric actuator, after the two reading heads pass through the zero point, the zero point information at the two reading heads is obtained. If the zero point information of one of the reading heads is invalid, it can be determined that the reading head is faulty.

[0013] Step 3: When one of the read heads fails, the other read head can be used for zero-point identification. At this time, the identification of the zero point cannot be accomplished by a single zero point. Multiple zero points need to be collected continuously to achieve identification. When enough zero-point information is cached to distinguish each zero point, when moving in the same direction, the zero-point information is exchanged in a first-in-first-out manner. At this time, the absolute position can be obtained through a zero point.

[0014] Preferably, the zero-point type is determined by the angle occupied by the zero point.

[0015] This invention has at least the following beneficial effects:

[0016] This invention discloses a dual-reader multi-zero-point positioning method for electric actuators, which enables rapid positioning of a relatively large number of different zero points within one revolution. The dual-reader method can cope with the failure of one reader, making the system more reliable. When a single reader is in the same direction, after experiencing a sufficient amount of zero-point information, its resolution capability is consistent with that of the dual-reader method, thus ensuring the reliability of the system. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a distribution diagram of the zero-point detection readheads of the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Example 1

[0020] Reference Figure 1It includes two zero-point detection read heads, and multiple zero points of a finite number of types are evenly distributed on the zero-point code track. The combination information of the two zero-point types determines the absolute position and performs multiple distinguishable zero-point positioning. The code disk includes a zero-point code track. The encoding is a combination of zero points. The combination of zero points is the combination of zero points at the two zero-point detection read heads, and at the same time, it is a combination of multiple zero points in the same direction at a single zero-point detection read head. The zero points are evenly distributed, and the center position of each zero point is evenly distributed on the code track. Example 2

[0021] Reference Figure 1 Zero-point information includes zero-point type and zero-point position. Zero-point information is obtained by recording the positions of the rising and falling edges of the read head during unidirectional movement. The position difference between the rising and falling edges is the angle of the zero point, which can be used to determine the zero-point type. The center point of the rising and falling edges is the position of the zero point. Example 3

[0022] Reference Figure 1 The rising and falling edges are obtained by comparing the light sensitivity measured by the read head with a specific voltage value through a comparator. When interference is introduced during the edge acquisition process, it will cause incorrect edge triggering, which will generate incorrect zero-point information, which is undesirable for position calibration. Example 4

[0023] Reference Figure 1 The system acquires all light sensing values ​​and encoder positions during the unidirectional movement of the reader. Due to the symmetry of light sensing, the center value of multiple positions with the same light sensing value is obtained, and the center position of the mode is obtained, thus avoiding position deviation caused by interference and obtaining a more accurate zero-point position. For angle information, since fault tolerance is added in the encoding design, the angles corresponding to various types of zero points are different. In the presence of interference, the acquired angle values ​​will be deviated. By determining which category the angle value is closer to, the zero-point type can be identified. Example 5

[0024] Reference Figure 1 The process of the two zero-point detection heads reading zero-point information involves the following steps:

[0025] Step 1: When the electric actuator leaves the factory, it will perform one cycle of forward and reverse rotation. During this cycle, the encoder position corresponding to each zero point mark will be calibrated and recorded. In subsequent actual operation, the absolute position of the current zero point can be obtained by looking up the table based on the zero point information. The position of the electric actuator can then be calibrated.

[0026] Step 2: During the operation of the electric actuator, after the two reading heads pass through the zero point, the zero point information at the two reading heads is obtained. If the zero point information of one of the reading heads is invalid, it can be determined that the reading head is faulty.

[0027] Step 3: When one of the read heads fails, the other read head can be used for zero-point identification. At this time, the identification of the zero point cannot be accomplished by a single zero point. Multiple zero points need to be collected continuously to achieve identification. When enough zero-point information is cached to distinguish each zero point, when moving in the same direction, the zero-point information is exchanged in a first-in-first-out manner. At this time, the absolute position can be obtained through a zero point. Example 6

[0028] Reference Figure 1 The type of zero point is determined by the angle occupied by the zero point.

[0029] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention. The scope of protection claimed by the appended claims and their equivalents is defined.

Claims

1. A dual-reader method for identifying multiple zero points in an electric actuator, comprising two zero-point detection readers, and multiple zero points of finite types evenly distributed on the zero-point code track, wherein the combination information of the types of the two zero points determines the absolute position, and multiple distinguishable zero-point positioning is performed, the code disk includes a zero-point code track, the encoding is a combination of zero points, the combination of zero points is a combination of zero points at the two zero-point detection readers, and at the same time, it is a combination of multiple zero points in the same direction at a single zero-point detection reader, the zero points are evenly distributed, and the center position of each zero point is evenly distributed on the code track; Zero-point information includes zero-point type and zero-point position. Zero-point information is obtained by recording the positions of the rising edge and falling edge of the read head during unidirectional movement. The position difference between the rising edge and the falling edge is the angle of the zero point, which can be used to determine the zero-point type. The center point of the rising edge and the falling edge is the position of the zero point. The rising and falling edges are obtained by comparing the light sensitivity measured by the read head with a specific voltage value through a comparator. When interference is introduced during the edge acquisition process, it will cause incorrect edge triggering, which will generate incorrect zero-point information. This is undesirable for position calibration. The system acquires all photosensitive values ​​and encoder positions during the unidirectional movement of the reader. Due to the symmetry of the photosensitive data, the center value of multiple identical photosensitive values ​​is calculated to obtain the center position of the mode, thus avoiding positional deviations caused by interference and obtaining a more accurate zero-point position. For angle information, since fault tolerance is added in the encoding design, the angles corresponding to various types of zero points are different. In the presence of interference, the acquired angle values ​​will be deviated. By determining which category the angle value is closer to, the zero-point type can be identified. The two zero-point detection heads read the zero-point information through the following steps: Step 1: When the electric actuator leaves the factory, it will perform one cycle of forward and reverse rotation. During this cycle, the encoder position corresponding to each zero point mark will be calibrated and recorded. In subsequent actual operation, the absolute position of the current zero point can be obtained by looking up the table based on the zero point information, which can then be used to calibrate the position of the electric actuator. Step 2: During the operation of the electric actuator, after the two reading heads pass through the zero point, the zero point information at the two reading heads is obtained. If the zero point information of one of the reading heads is invalid, it can be determined that the reading head is faulty. Step 3: When one of the read heads fails, the other read head can be used for zero point identification. At this time, the identification of the zero point cannot be accomplished by a single zero point. Multiple zero points need to be collected continuously to achieve identification. When enough zero point information is cached to distinguish each zero point, when moving in the same direction, the zero point information is exchanged in a first-in-first-out manner. At this time, the absolute position can be obtained through a zero point. The zero-point type is determined by the angle occupied by the zero point.

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