RU2020752C1 - Shaft angle-of-turn-to-code converter - Google Patents

Abstract

FIELD: measurement technology and automatic control. SUBSTANCE: series-connected first and second EXCLUSIVE OR gates and inverter, counter and electronic vernier unit, and second comparator, as well as new ties are introduced in converter. EFFECT: improved speed and accuracy, as well as length of output code. 3 dwg

Description

 The invention relates to electrical engineering and automation and can be used to convert signals from sensors such as SKT and the like into digital binary code.

 Known digital displacement transducer that implements the deployment of the conversion of the angle-amplitude-time interval code [1].

 Sources of error in converting the signal amplitude to the time interval in it are analog demodulators, a differential amplifier, multiplying the DACs and a sine and cosine code generator based on ROM with sine firmware.

 Closest to the proposed one is a converter of the angle of rotation of the shaft into a code with an intermediate conversion of the amplitude to the time interval, containing a high-frequency pulse generator, a power supply unit for a sine-cosine angle sensor (SKDU), consisting of a frequency divider and a filter connected in series, an octant switch, a phase-shifting element , half-wave rectifiers, comparator, time interval meter [2].

 The source of error in the prototype are two-half-wave rectifiers that distort both the magnitude and shape of the rectified signals.

 The aim of the invention is to improve the accuracy of conversion while maintaining high performance.

= -U_mcosθsinωt,, (1) где U_m - амплитуда сигнала;
θ - угол поворота оси датчика;
ω - несущая частота, предлагается первый из сигналов линейно преобразовать в вид
U_s ^* = U_m sinθ cosωt ₍₂₎ (например, с помощью инвертирующего интегратора), сравнить на двух компараторах с двумя оставшимися входными сигналами и по результатам сравнения с помощью элемента ИСКЛЮЧАЮЩЕЕ ИЛИ выделить временной интервал, пропорциональный углу θ.To achieve the goal in the presence of converting signals typical for sensors of type SKT
U _s = U _m sinθsin ωt;
U _c = U _m cosθsinωt;

= -U _m cosθsinωt ,, (1) where U _m is the signal amplitude;
θ is the angle of rotation of the axis of the sensor;
ω is the carrier frequency, it is proposed to linearly convert the first of the signals into a form
U _s ^* = U _m sinθ cosωt ₍₂₎ (for example, using an inverting integrator), compare on two comparators with the two remaining input signals and, using the EXCLUSIVE OR element, select a time interval proportional to the angle θ from the results of the comparison.

 For this purpose, a second comparator, two EXCLUSIVE OR logic elements, an counter, an electronic nonius block, and also new connections are introduced into a known converter containing a high-order driver, for example a quadrant driver, a key, a comparator, an integrator and a pulse generator.

 Figure 1 shows the structural diagram of the Converter angle of rotation of the shaft in the code; figure 2 is a block diagram for determining the quadrant; figure 3 is a timing diagram explaining the operation of the unit for determining the quadrant.

 The converter contains a high-level driver, made in the form of a quadrant definition block 1, a key 2, a pulse counter 3, an integrator 4. comparators 5 and 6, elements EXCLUSIVE OR 7 and 8, an inverter 9, a pulse generator 10, an electronic nonius block and SKDU 12 .

 Block 1 of the definition of the quadrant contains the comparators 13, 14 and the element EXCLUSIVE OR 15.

 In order to increase the speed of the converter, a quadrant selector and an octant selector can be used along with block 1 for determining quadrants as a shaper of higher digits.

 Introduction to the transducer of the generator 10 can increase the accuracy of the conversion. Introduction to the converter unit 11 electronic nonius with an additional counter allows you to increase the capacity of the Converter without increasing the clock frequency.

Block 1 generates two senior bits of the angle code, corresponding to angles 180 and 90 ^about .

 As a synchronized generator 10 can be used chip 564GG1.

 The converter operates as follows.

Using the inverting integrator 4 signal
U _s = U _m sinθsinωt is converted into a signal
U _s ^* = U _m sinθ cosωt (Fig. 3a).

и U_s ^* и выделяют на входе ключа временные интервалы
t_и=

. (3)
Временные интервалы заполняются частотой f_т (фиг.3б, в,г) и на счетчике 3 импульсов образуется код всех остальных младших разрядов.Comparators 5, 6 compare signals U _c ,

and U _s ^* and allocate time intervals at the key input
t _and =

. (3)
The time intervals are filled with a frequency f _t (fig.3b, c, d) and on the counter 3 pulses a code of all other lower digits is formed.

 The total time of one conversion cycle does not exceed half the period of the carrier frequency and can be further reduced when using not a quadrant shaper but an octant selector as shaper 1.

.From formula (3) it follows that the converter does not have all the most important methodological errors, including differential nonlinearity, and the main error is the stability of the carrier frequency, which, when stabilized by quartz, can reach values of the order of 10 ^-6 -10 ^-7 . But this error can also be reduced by synchronizing the carrier and clock frequencies, since the angle code
N _θ =

.

 As mentioned above, the conversion bit can be increased without increasing the clock frequency and conversion time using electronic nonius.

The instrumental error is determined mainly by the errors of the integrator and comparators, which, with the modern element base, allows reaching values of the order of 10 ^-5 -10 ^-6 , i.e. accurate conversion of 18-20 binary digits.

 The best modern measuring instruments and digital AC voltmeters have an accuracy of not more than 0.01%.

Claims (1)

 A SHAFT ANGLE CONVERTER TO A CODE containing a sine-cosine angle sensor, whose sine and cosine outputs are connected to a quadrant detection unit, the outputs of which are the high-order outputs of the converter, the first comparator, key, integrator, pulse generator, characterized in that, for the purpose of to increase its speed and accuracy, as well as the bit depth of the output code, a second comparator, two EXCLUSIVE OR elements, an inverter, counter, electronic nonius block, cosine and inverse cosine are introduced into it The outputs of the sine-cosine angle sensor are connected to the direct inputs of the first and second comparators, the outputs of which are connected to the inputs of the first EXCLUSIVE OR element, the output of which is connected to one input of the second EXCLUSIVE OR element, the output of which is connected through the inverter to the control input of the key and the input of the unit electronic nonius, the key output is connected to the counter input, the outputs of which and the outputs of the electronic nonius block are the low-order outputs of the converter, the sine output is sine-cosine through the integrator is connected to the inverse inputs of the first and second comparators and directly to the synchronization input of the pulse generator, the output of which is connected to the information input of the key, the output of the least significant bit of the quadrant detection unit is connected to the other input of the second EXCLUSIVE OR element.

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