CN109297516A  A kind of rotary transformer coding/decoding method suitable for smallangle movement range  Google Patents
A kind of rotary transformer coding/decoding method suitable for smallangle movement range Download PDFInfo
 Publication number
 CN109297516A CN109297516A CN201811091549.0A CN201811091549A CN109297516A CN 109297516 A CN109297516 A CN 109297516A CN 201811091549 A CN201811091549 A CN 201811091549A CN 109297516 A CN109297516 A CN 109297516A
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 China
 Prior art keywords
 angle
 rotary transformer
 movement range
 kind
 small
 Prior art date
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 238000000034 methods Methods 0.000 description 5
 238000004364 calculation methods Methods 0.000 description 1
 230000000694 effects Effects 0.000 description 1
 238000004088 simulation Methods 0.000 description 1
Classifications

 G—PHYSICS
 G01—MEASURING; TESTING
 G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
 G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
 G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
 G01D5/14—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage
 G01D5/20—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature
 G01D5/22—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature differentially influencing two coils
 G01D5/2291—Linear or rotary variable differential transformers (LVDTs/RVDTs) having a single primary coil and two secondary coils
Abstract
Description
Technical field
The invention belongs to rotary transformer angle field of measuring technique, are related to a kind of suitable for (± 45 °) of lowangle movements The rotary transformer coding/decoding method of range.
Background technique
Rotary transformer is a kind of widely used angle measurement element, but the simulation cosine and sine signal of its output cannot be direct It uses, angle signal can be just converted by needing to configure dedicated decoding circuit.If not using dedicated decoding circuit, need Collected cosine and sine signal is handled, surmounts function to obtain angle finally by arc tangent is calculated.
The present invention does not need to surmount function using dedicated decoding circuit without complicated algorithm to resolve arc tangent.Needle The characteristics of to trigonometric function, the angle that the decoding to signals of rotating transformer can be completed, while resolving using simple computation Precision index with higher is spent, the use suitable for general control systems.
As shown in Figure 1, rotary transformer feedback signal is just remaining by the fixed frequency of sinusoidal rule modulation by angle information String wave.The method of angle information is calculated from analog signal at present there are mainly two types of method, one of method uses dedicated Decoding chip, decoding principle are to construct secondorder loop using phaselocked loop, carry out Closed loop track decoding；Another method is using A/ D chip acquires cosine and sine signal, tangent signal is formed after operation, then count by resolving arctan function (such as Cordic algorithm) Calculate angle.
Above two method has certain defect, at high cost using dedicated decoding chip, circuit is complicated；Using arc tangent Function computation need to consume a large amount of operational capability of processor, higher to system hardware Platform Requirements.
Summary of the invention
Technical problems to be solved
In order to avoid the shortcomings of the prior art, the present invention proposes one kind for lowangle (± 45 °) motion range Using the characteristics of making full use of trigonometric function is decoded using the angle that rotary transformer can be completed in simple computation.
Technical solution
A kind of rotary transformer coding/decoding method suitable for smallangle movement range, it is characterised in that steps are as follows:
Step 1: thick to calculate:
To in a signal period data carry out summation operation, thus obtain it is discrete after sine wave semiarea it is equivalent Value, such as following formula:
Wherein, U_{s}For the semiarea of sinusoidal signal, U_{c}For the semiarea of cosine signal；
It calculates
Angle is calculated by A
Step 2: essence calibration:
Photoelectric encoder and tested mechanism are coaxially mounted, multiple point datas are tested within the scope of mechanism kinematic and obtain one group Angle value；The angle value that test obtains and the angle value that step 1 is calculated are repaired using higher order polynomialfitting method Just, polynomial order is between 3~10.
Beneficial effect
A kind of rotary transformer coding/decoding method being suitable for lowangle (± 45 °) motion range proposed by the present invention, is not required to Special circuit is wanted, algorithm calculates simple.
Detailed description of the invention
Fig. 1 rotary transformer feeds back sine and cosine analog signal
Angle error curve (abscissa: points, ordinate: angular error (unit °)) after Fig. 2 is slightly decoded
The revised angular error curve of Fig. 3 essence (abscissa: points, ordinate: angular error (unit °))
Specific embodiment
Now in conjunction with embodiment, attached drawing, the invention will be further described:
The present invention completes the rotary transformer decoding of smallangle movement range in two steps, and the first step is slightly to decode, and second Portion is essence calibration.
1.2.1 thick decoding principle
The signal that rotary transformer is fed back to is as shown in Figure 1, its mathematical expression are as follows:
Angle signal is modulated to the amplitude of fixed frequency sinusoidal signal, but the amplitude of sinusoidal signal is difficult to acquire, therefore Equivalent Calculation, such as following formula are carried out using the semiarea of sine wave in the present invention:
U_{s}The semiarea of sinusoidal signal, U_{c}The semiarea of cosine signal enablesBy can be calculated:
It can be obtained by (3),When the angle θ is in small angle range, it can be approximately considered cot θ ≈ θ, therefore (3) Formula transformation are as follows:
It can be obtained by (4),Therefore, angle can be solved by calculating the area of halfsine wave.
1.2.2 smart calibrating principle
The angular error curve obtained using 3.2.1 method is the parabola that Open Side Down in motion range, Zero point goes out error maximum.In order to reach higher angle measurement accuracy, the angle obtained to 3.2.1 method is needed to be modified.
Modification method employed in the present invention is higher order polynomialfitting method, and polynomial order is (full between 3~10 Sufficient angular error is at 1 °).It needs coaxially to pacify using highprecision (≤0.05 °) photoelectric code disk with device is corrected in makeover process Dress, and synchronous acquisition photoelectric code disk data (angle) and 3.2.1 method calculated result.In makeover process, by adjusting multinomial Order satisfies the use demand error.
By taking certain control system as an example, angular movement range is ± 15 °, and the exciting signal frequency of rotary transformer is 2KHz, The acquisition of A/D data uses 100KHz sample rate.
In the processor in a signal period data carry out summation operation, thus obtain it is discrete after sinusoidal signal Period area equivalence value, such as following formula:
Realtime angular information is calculated further according to the algorithm in 3.2.1, completes thick decoded process.At this point, angular error Larger, error curve is as shown in Figure 2.
Photoelectric encoder and tested mechanism are coaxially mounted using test fixture, 40 points are tested within the scope of mechanism kinematic According to and carry out refine just.By adjusting polynomial order is corrected, final determine uses 5 rank multinomials, error curve such as Fig. 3 It is shown.
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Citations (4)
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CN101038182A (en) *  20060315  20070919  欧姆龙株式会社  Resolver signal processing device 
CN102519353A (en) *  20111118  20120627  中国兵器工业第二〇六研究所  Method based on FPGA (Field Programmable Gate Array) for acquiring angle signal of magnetic position sensor 
CN105703773A (en) *  20141128  20160622  中国科学院沈阳自动化研究所  Rotary transformer decoding method 
CN107843227A (en) *  20171209  20180327  连云港杰瑞电子有限公司  A kind of method that encoder accuracy is improved based on collimation technique 

2018
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Patent Citations (5)
Publication number  Priority date  Publication date  Assignee  Title 

CN101038182A (en) *  20060315  20070919  欧姆龙株式会社  Resolver signal processing device 
JP2007248246A (en) *  20060315  20070927  Omron Corp  Resolver signal processing device 
CN102519353A (en) *  20111118  20120627  中国兵器工业第二〇六研究所  Method based on FPGA (Field Programmable Gate Array) for acquiring angle signal of magnetic position sensor 
CN105703773A (en) *  20141128  20160622  中国科学院沈阳自动化研究所  Rotary transformer decoding method 
CN107843227A (en) *  20171209  20180327  连云港杰瑞电子有限公司  A kind of method that encoder accuracy is improved based on collimation technique 
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