RU2161772C2 - Angle determination device - Google Patents

Abstract

FIELD: measuring technology. SUBSTANCE: device is intended for determination of angular position of shaft or other member of actuating mechanism. Device has an angle-data transmitter with three phase outputs, for example, selsyn connected to inputs of synchronous demodulator. Three multipliers provide for multiplication of signals at synchronous demodulator output with output signals of three phase inverters. Sum of products obtained at adder output is integrated by integrator and displayed on indicator. Zero-setting unit of device is connected to feedback circuit placed between integrator output and inputs of phase inverters. EFFECT: higher accuracy. 1 dwg

Description

 The invention relates to measuring equipment, in particular to devices for determining the angular position of a shaft or other element of the actuator.

 A device for determining the angle is known, comprising an angle sensor, a demodulator and an indicator (see US Pat. No. 5,466,665).

 This device, however, has low accuracy and the need to have a multiphase reference voltage supply system.

 Closest to the present invention, a prototype of it, is a converter of the angle of rotation of the shaft into voltage according to ed. St. N 1247647 A1 dated 07/30/86, G 01 B 7/30, comprising an angle sensor with three phase outputs connected to the inputs of a synchronous demodulator.

 The disadvantage of the prototype device is the low accuracy due to the presence of elements - sources of nonlinear distortion.

 The objective of the invention is to improve the metrological characteristics of the prototype device.

 The technical result achieved by using the invention is to increase the accuracy of determining the angle.

The specified technical result is achieved by the fact that the first, second and third multipliers, the first, second and third phase shifters, an adder, an integrator, a zero-setting unit and an indicator are introduced into the prototype device, and the inputs of the multipliers are connected in pairs, respectively, to the outputs of the demodulator and phase shifters , and the outputs - to the inputs of the adder, the output of which through the integrator is connected to the inputs of the indicator and the installation block "zero", the output of which is connected to the inputs of the phase shifters. In this case, the nonlinearity of the end-to-end characteristic of converting the angle of rotation of the sensor into indicator readings is suppressed by introducing certain functional relationships into the controlled phase shifters that depend on the characteristics of the sensor and using a phase-by-phase comparison circuit of the output voltages of the demodulator and phase shifters based on multipliers, the integral of the sum of the output voltages of which is proportional angle of rotation of the sensor and independent of supply voltage and "residual" phase voltage this sensor. "
We explain the invention according to the block diagram of the proposed device for determining the angle, where it is indicated: 1 - an angle sensor with three phase outputs, for example, selsyn; 2 - synchronous demodulator, the inputs of which are connected to the outputs of the sensor 1; 3, 4, 5 - the first, second and third multipliers; 6, 7, 8 - the first, second and third phase shifters; 9 - adder; 10 - integrator; 11 - unit for setting the “zero” indicator 12; 12 - indicator of the angle of rotation of the sensor 1 relative to its "zero" position.

The power supply and mutual synchronization of the sensor 1 and the demodulator 2 is designated as U _p (according to the voltage acting in it). The first, second and third outputs of the sensor and demodulator are indicated by the letters a, _b , c, the voltage at the outputs of blocks 1, 2, 3, ..., 11 - respectively, as U _1a U _1b , U _1s ; U _2a U _2b , U _2c ; U ₃ , ..., U ₁₁ . The inputs of the first multiplier (multiplier 3) are connected to the first output of the demodulator (to output a) and to the output of the first phase shifter (phase shifter 6), the inputs of the second multiplier (multiplier 4) are connected to the second output of the demodulator (to output c) and to the output of the second phase shifter ( phase shifter 7), the inputs of the third multiplier (multiplier 5) - to the third output of the demodulator (to output c) and to the output of the third phase shifter (phase shifter 8). The outputs of the multipliers 3, 4, 5 are connected to the inputs of the adder 9, the output of the latter to the input of the integrator 10, the output of the latter to the inputs of the indicator 12 and block 11, the output of the latter to the inputs of the phase shifters 6, 7, 8.

 The device operates as follows.

The dependence of the voltages at the phase outputs a, _b , c of the sensor 1 on the angular position α of this sensor and the carrier frequency ω of its supply voltage U _p has the form
U _1a = K ₁ U _n SinωtSinα,
U _1b = K ₁ U _n SinωtSin (α + 120 ^° ),
U _1c = K ₁ U _п SinωtSin (α-120 ^° ), where K ₁ is the proportionality coefficient, t is time.

The voltages at the outputs a, b, from the demodulator 2 are of the form
U _2a = U _d Sinα,
U _2b = U _d Sin (α + 120 ^° ),
U _2c = U _d Sin (α-120 ^° ),
where U _d is the amplitude value of the stresses U _2a , U _2b , U _2c .

The voltage U ₁₀ at the output of the integrator 10 is displayed by the indicator 12 in the dimension of the angle β equal to, as will be shown below, the difference (α-α ₀ ), where α ₀ is the value of the angle α, taken as the reference point and set in the installation unit 11 " zero "indicator 12.

Let β = K ₂ U ₁₀ , U ₁₁ = K $\genfrac{}{}{0ex}{}{\text{*}}{\text{2}}$ (β + α ₀ ), where K ₂ , K ₂ ^* are the proportionality coefficients. The circuit of phase shifters 6, 7, 8 is such that when the control voltage U ₁₁ changes at the outputs, we have
U ₆ = U _φ Cos (β + α ₀ ),
U ₇ = U _f Cos ((β + α ₀ ) +120 ^° ),
U ₈ = U _f Cos ((β + α ₀ ) -120 ^° ),
where U _f - the amplitude value of the stresses U ₆ , U ₇ , U ₈ .

где K₃, K₃ ^* = 3/2 K₃ - коэффициенты пропорциональности.As a result of pairwise multiplication of voltages at the inputs of blocks 3, 4, 5 and summation of the products obtained in block 9 at the output of the latter, we have

where K ₃ , K ₃ ^* = 3/2 K ₃ are the proportionality coefficients.

где K₄ - коэффициент пропорциональности, τ - переменная интегрирования (время). При этом блоки 6, 7, 8 и 11 по отношению к блокам 3, 4, 5 и 9, 10 образуют цепь отрицательной обратной связи, автоматически обеспечивающей устойчивое равновесие (баланс состояний) при выполнении условия U₉ = 0, откуда следует (α-β-α₀) = 0 или β = α-α₀.
Любое изменение углового положения датчика 1, т.е. величины (α-α₀), приводит к нарушению равенства U₉ = 0 и, следовательно, к такому дальнейшему изменению напряжения U₁₀ на выходе интегратора 10, что фазовый сдвиг угла β = K₂U₁₀ и соответствующие ему значения напряжений U₆, U₇, U₈ на выходах фазовращателей приводят к восстановлению равновесия, т.е. равенства U₉ = 0, при новом значении напряжения U₁₀; одновременно восстанавливается и равенство β = α-α₀. Таким образом, напряжение U₁₀ на выходе интегратора 10 и показания β индикатора 12 являются эквивалентами угла поворота датчика 1 относительно его начального ("нулевого") положения α₀.
Подчеркнем, что связь U₁₀ с интегралом от U₉ отражает лишь динамику изменения этого напряжения во времени. Что касается статики, то она характеризуется условием равновесия: U₉ = 0, что возможно только при соблюдении равенства β = α-α₀ или U₁₀= (α-α₀)/K₂ и не зависит от параметров K₃, K₄, U_д, U_ф, t. Повышенная точность определения углового положения датчика в предложенной схеме обусловлена именно этим обстоятельством.The voltage U ₉ in block 10 is integrated so that at the output of block 10 we have

where K ₄ is the proportionality coefficient, τ is the integration variable (time). In this case, blocks 6, 7, 8, and 11 with respect to blocks 3, 4, 5, and 9, 10 form a negative feedback circuit that automatically ensures stable equilibrium (state balance) when the condition U ₉ = 0 is fulfilled, from which it follows (α- β-α ₀ ) = 0 or β = α-α ₀ .
Any change in the angular position of sensor 1, i.e. of the quantity (α-α ₀ ) leads to a violation of the equality U ₉ = 0 and, therefore, to such a further change in the voltage U ₁₀ at the output of the integrator 10 such that the phase shift of the angle β = K ₂ U ₁₀ and the corresponding voltage values U ₆ , U ₇ , U ₈ at the outputs of the phase shifters lead to the restoration of equilibrium, i.e. equality U ₉ = 0, with a new voltage value U ₁₀ ; at the same time, the equality β = α-α _{0 is} also restored. Thus, the voltage U ₁₀ at the output of the integrator 10 and the readings β of the indicator 12 are equivalent to the angle of rotation of the sensor 1 relative to its initial ("zero") position α ₀ .
We emphasize that the relationship between U ₁₀ and the integral of U ₉ reflects only the dynamics of this voltage over time. As for statics, it is characterized by the equilibrium condition: U ₉ = 0, which is possible only if the equality β = α-α ₀ or U ₁₀ = (α-α ₀ ) / K ₂ and does not depend on the parameters K ₃ , K ₄ , U _d , U _f , t. The increased accuracy of determining the angular position of the sensor in the proposed scheme is due precisely to this circumstance.

Claims (1)

 A device for determining the angle, comprising an angle sensor with three phase outputs connected to the inputs of the synchronous demodulator, characterized in that the first, second and third multipliers, the first, second and third phase shifters, an adder, an integrator, a zero-setting unit and an indicator are input, and the inputs the multipliers are connected in pairs respectively to the outputs of the demodulator and phase shifters, and the outputs are connected to the inputs of the adder, the output of which is connected through the integrator to the inputs of the indicator and the zero-setting unit, the output of which is connected phase shifters inputs.