RU2082088C1 - Method of measurement of angular position of shaft - Google Patents

Abstract

FIELD: measurement technology. SUBSTANCE: method of measurement of angular position of shaft consists in placement of transducer generating signals with known relative pulse duration with reference to tested shaft with disc having gear ring with teeth arranged uniformly and some of them missing. Present period of sequence of signals of transducer is measured, marker pulse corresponding to miss of teeth and angular pulses corresponding to teeth on disc are formed, number of angular pulses formed after marker pulse is counted and used to find angular position of tested shaft. Extraction and rejection of noise pulses is carried out prior to formation of angular pulses. For this comparison of constant of transducer and correction taking into account maximum possible brake of tested shaft over front of each signal of transducer with ratio of preceding sequence period to current sequence period is performed at first stage. Noise pulse is determined either at first stage if zero logic level of signal of transducer is read or at second stage if relation of preceding period of sequence of signal of transducer to current period of sequence of signal of transducer is less than constant. EFFECT: enhanced authenticity of measurements. 5 dwg

Description

 The invention relates to measuring technique, in particular, to measuring the angular position of the shaft of an internal combustion engine (ICE) equipped with an electronic digital control system.

 A known method of measuring the angular position of the ICE shaft (ed. St. USSR N 917708, class F 02 P 5/08, 1982), which consists in the fact that two pulse sensors are placed relative to a controlled rotating shaft, equipped with a disk with a ring gear and a single marker tooth, and the first sensor is placed above the crown, which has evenly cut teeth, and the second sensor is above a single marker tooth. The measurement of the angular position is carried out by counting the angular pulses generated by the first sensor relative to the reference pulse generated by the second sensor.

 This method is cumbersome, since it requires two sensors and the corresponding number of connections and signal conditioners. In addition, this method has low noise immunity in conditions of impulse noise, for example, from the engine ignition system, which causes a malfunction in the engine control system.

 The prototype is a method of measuring the angular position of the ICE shaft (ed. St. USSR N 1728642, class G 01 B 7/30, 04/23/92), which is as follows. A single impulse sensor is placed relative to the monitored shaft, equipped with a toothed disk having uniformly cut teeth, with several teeth missing. When the sensor shaft rotates, it generates pulses corresponding to the passage of the teeth of the disk of the controlled shaft past it. By measuring the current pulse repetition period generated by the sensor and comparing it with the previous pulse repetition period, a marker pulse is extracted and angular pulses are calculated relative to the marker pulse.

 This method also has low noise immunity in conditions of impulse noise, for example, from the internal combustion engine ignition system.

 The technical result of the invention is to increase the reliability of measuring the angular position of the shaft under conditions of impulse noise, for example, from the ignition system of the internal combustion engine.

 This result is achieved by the fact that in the method of measuring the angular position of the shaft, which consists in the fact that relative to the controlled shaft, equipped with a disk with a gear rim having uniformly spaced teeth and several missing teeth, a sensor is placed that generates signals from a known tooth during rotation of the shaft duty cycle, measure and remember the current period of the following sensor signals, form a marker pulse corresponding to the tooth gap on the controlled shaft, and angular pulses, respectively the teeth on the disk of the controlled shaft, count the number of angular pulses generated after the marker pulse generated after the marker pulse, determine the angular position of the controlled shaft before the formation of the angular pulses, select and reject interference pulses, for which, on the front of each sensor signal, in the first stage comparing the constant, which is the sum of the duty cycle of the sensor signals and the correction taking into account the braking of the controlled shaft, the ratio of the repetition period previous to the current repetition period, the disturbance pulse is determined either in the first step, if the read zero logic level of the sensor signal or the second stage, if the previous repetition period of the sensor signal related to the current repetition period smaller than the constant sensor signal.

 In FIG. 1 presents a structural diagram of a device that implements the inventive method. In FIG. 2 voltage waveform at the output of the sensor signal shaper in the absence of an interference pulse. In FIG. 3 waveform of the voltage at the output of the sensor signal shaper in the case of an impulse interference is applied to the sensor signal low level. In FIG. 4 waveform of the voltage at the output of the shaper in the case of an impulse of an interference pulse at a high level of the sensor signal. In FIG. 5 is a structural diagram of an interrupt processing algorithm along the edge of a sensor signal.

Designations adopted on the oscillograms:
T _p previous stored period of the signal from the sensor;
T _{m the} current measured period of the sensor signal;
U duration of a high level sensor signal,
U _{p the} duration of the interference pulse.

 Duty rate is defined as the ratio of the period of the sensor signals to the duration of a high signal level.

 A device for its implementation includes a toothed disk 1 with 58 teeth and two missing teeth mounted on a controlled shaft, a sensor 2 located above the toothed disk 1 and connected to the sensor signal generator 3. The output of the sensor signal generator 3 is connected to the external interrupt input of the microprocessor 4, which in turn is connected to the storage device 5, in which the interrupt processing program is stored. The microprocessor 4 has an output, which displays information about the angular position of the controlled shaft.

 The method can be implemented as follows. A pulse sensor is placed above the ring gear, rigidly connected with the controlled shaft. The sensor may be, for example, induction based on the Hall effect, or optical. The ring gear may have, for example, 58 and two missing teeth. A delay time is exceeded on the edge of the sensor signal, exceeding the duration of the interference pulse, for example, using a delay line or a timer, and then the logical level of the sensor signal is read.

 If the read level is a logic zero, then the sensor signal is considered an interference. According to the impulse, the interference does not produce any action and goes into standby mode for the next sensor signal. If the read logic level is a logical unit, then measure the period of the signals of the sensor, for example, by counting over time from the appearance of the front of the signal to the front of the next signal of the number of pulses of the master oscillator. The calculated number of pulses of the master oscillator is stored, for example, in a counter, register, or in a random access memory (RAM) cell. The ratio of the current period of the sensor signals to the previous one is calculated. This can be done by dividing the current following period by the previous memorized period, for example, in an arithmetic logic unit (ALU) or using a microprocessor. Comparison of the obtained relationship with a constant, which is the sum of the duty cycle of the sensor signals and corrections, taking into account the maximum possible braking of the shaft. If the obtained ratio is less than the specified constant, then this signal is considered an interference induced, for example, from the ignition system of the internal combustion engine, further signal processing is stopped, the measured period is not memorized and goes into standby mode for the next sensor signal. If the obtained ratio is greater than the above constant, then this sensor signal is considered a valid signal and further formation of marker and / or angular pulses is performed on it. The formation of a marker pulse is produced, for example, when the current period of the sensor signals exceeds the previous memorized period by more than two times. The formation of angular pulses is carried out, for example, for each valid sensor signal. Angular pulses are counted, starting from the moment the marker pulse is generated, for example, using a software counter based on a register, a RAM cell, or a separate microcircuit. At the same time, an increment of the counter is performed for each angular pulse, and a counter is zeroed for each marker pulse. The number of angular pulses counted by the counter at a given time will indicate the current angular position of the shaft relative to the position of the marker mark (in this example, two missing teeth).

 The inventive method was implemented in software in the controller of the engine control system of a VAZ-2110 car.

 A device that implements the method operates as follows. When the shaft rotates, the teeth and troughs move in front of the sensor 2, which at the same time generates signals. The signal generator of the sensor 3 converts the signals of the sensor 2 into a form suitable for the microprocessor 4. The pulses from the output of the signal generator of the sensor 3 are fed to the input of the external interrupts of the microprocessor 4.

 In the process of generating pulses by the sensor 2 and transmitting them to the shaper 3, interference pulses can be superimposed on the sensor signals, for example, from the engine ignition system, and thus a signal representing the sum of the sensor signals and the interference will be transmitted to the microprocessor interrupt input. On the edge of this signal, a microprocessor, for example, Siemens 80517, interrupts the main program for processing an external interrupt.

The interrupt processing algorithm shown in FIG. 5 shows the steps for processing the sensor signal according to the proposed method. To measure the period of the sensor signal from front to front, a microprocessor timer device is used. In this example of a software implementation, the block in which the marker pulse is generated is not shown. This block can be performed, as in the prototype, by comparing the current period of the sensor signal with the doubled previous period, since the marker mark (missing two teeth) corresponds to the double period of the sensor signals when passing teeth in front of it. At the beginning of the algorithm, there is a delay for the time characteristic of the interference pulse (of the order of several microseconds). The delay can be performed using the counter-timer or by executing empty commands (NOP commands). After the delay, the signal level at the interrupt input is checked. If the signal level at the input is low, this means that the interruption occurred not from the actual sensor signal, but from interference, and the interrupt processing is exited without remembering the current period. If the signal level is high, then the ratio of the previous memorized period T _p to the current measured T _{m is} calculated and compared with the constant (Q + dQ), and if the ratio is less, then this means that the interruption occurred from interference, while exiting interrupt processing without remembering the current period. The opposite case means that the interruption came from a real impulse. In this case, the current measured signal period is stored and the program counter is incremented. After that, the number of pulses counted by the software counter is compared with the number of teeth on the ring gear. If the number of pulses does not exceed the number of teeth, then a normal exit from the interrupt occurs. If the counter reading exceeds the number of teeth, an error message is generated and resynchronization is carried out, that is, the transition to the subroutine of the initial location of the marker mark (formation of the marker pulse).

Claims (1)

 A method of measuring the angular position of the shaft, which consists in the fact that relative to the controlled shaft, equipped with a disk with a gear rim having uniformly spaced teeth and several missing teeth, a sensor is placed that generates a signal with a known duty cycle during movement of the shaft of the teeth, the current period is measured and stored following the sensor signals form a marker pulse corresponding to the missing teeth on the controlled shaft, and angular pulses corresponding to the teeth on the disk of the controlled shaft a, the number of angular pulses generated after the marker pulse is calculated, and the angular position of the monitored shaft is determined by the number of calculated angular pulses, characterized in that before the formation of the angular pulses, interference pulses are extracted and discarded, for which, at the first stage, the front of each sensor signal is produced comparing the constant, which is the sum of the duty cycle of the sensor signals and the correction, taking into account the braking of the controlled shaft, with the ratio uschego repetition period of the current repetition period, and the pulse interference is determined either in the first step, if the read zero logic level of the sensor signal or the second stage, if the previous repetition period of the sensor signal related to the current repetition period smaller than the constant sensor signal.

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