CN106402085A - Signal pretreatment method for magnetic-grid-like hydraulic cylinder integrated displacement sensor - Google Patents

Abstract

The invention discloses a signal pretreatment method for a magnetic-grid-like hydraulic cylinder integrated displacement sensor. Errors possibly caused in the process of processing and mounting are considered, and an output signal of the sensor often contains a DC component and pulse interference. According to the signal pretreatment method disclosed by the invention, a high-pass filter enters a steady working state in advance, so that the DC component is effectively filtered out; and in accordance with the pulse interference existing in the signal, a high-frequency sampling signal is combined for use, a condition that two increments are approximately equal is utilized, and a signal valve before interference is estimated, so that all-frequency high-precision on-line filtering is realized.

Description

One species magnetic grid hydraulic cylinder integrated displacement sensor Signal Pre-Processing Method

Technical field

The present invention relates to signal processing technology field, it is mainly used in the displacement measurement side of Aero-Space hydraulic actuation mechanism Face.

Background technology

Electrohydraulic control system has a wide range of applications in Aeronautics and Astronautics field, and hydraulic cylinder is as the pass of electrohydraulic control system Key execution unit, the high precision of its displacement, highly reliable measurement are most important to system precise control.With plane hydraulic system court High-pressure trend, the high-power, direction such as pressure changeable, integrated, redundance is developed, the novel hydraulic with cramped construction makees motivation Structure, such as Electrical hydrostatic actuator, single rod asymmetric cylinder etc., increasingly receive publicity.Compare conventional cylinder displacement measurement mode, Class magnetic grid integrated displacement sensor energy effectively solving installs interference, the problem of the aspect such as not easy-maintaining, length limited, simultaneously by In its high integration in that context it may be convenient to carry out integrated with novel hydraulic actuation mechanism such as EHA, structural advantage is obvious.

Class magnetic grid hydraulic cylinder integrated displacement sensor is born in BOSCH-REXROTH group company, is currently the only to have actual product The piston rod scale displacement transducer of application.But the error that may bring in view of processing with when installing, sensor output letter Number often contain some defects, and output signal belongs to continuous periodic analogue signal, also cannot be used directly for high accuracy Hydraulic cylinder displacement measurement.The pretreatment of sensor output signal has directly influenced the certainty of measurement of hydraulic cylinder displacement, for this The invention discloses a species magnetic grid hydraulic cylinder integrated displacement sensor Signal Pre-Processing Method.

Content of the invention

DC component in response signal derives from static stimulation magnetic field when sensing head works.Due to working sensor When, need by piston rod scale period structure, this static stimulation magnetic field to be modulated, make sensing element produce periodic response. Therefore, this static magnetic field be the basis of periodic response it is impossible to directly eliminate from root, can only be from signal output part by this direct current Component filters.With reference to existing technology, high-pass filter is reasonable mode.DC component is filtered using high-pass filter When, signal has a larger time delay of ratio in the starting stage, increases over time, and wave filter progresses into steady operation shape State, in this condition, high-pass filter can effectively filter out DC component.And the time delay of starting stage, result from DC component Stepped Impedance Resonators.Therefore, high-pass filter enters steady-working state is the premise that DC component filters.For guaranteeing high-pass filter Steady operation, before sensor smooth working, need to have certain preheating time, and the big I of preheating time is by the amplitude of DC component With the corresponding construction parameter determination in transmission function.

Impulse disturbances are occurred in response signal with random amplitude and position, belong to interference signal.For ensureing sensor Certainty of measurement, in real work, need to effectively eliminate this interference.But the Frequency Spectral Theory from signal, pulse signal belongs to Full range band signal, has typically non-linear, only to filter form by signal frequency, is difficult to be eliminated.For this vast section Skill personnel have carried out substantial amounts of exploration, have developed multiple pulse signal filtering methods.As signal medium filtering, difference sequence pulse The cognitive filter of noise measuring method DRID (Differentical Rank Impulse Detector), improved DRID method, signal Division etc., filters in pulse signal method existing, medium filtering is the more commonly used method, but the method cannot be effective Adapt to frequency situation of change, and the method time delay is larger；Difference sequence impulse noise detection method DRID and its innovatory algorithm fortune Calculation amount is than larger it is adaptable to offline occasion；Signal cognition filters method and need in advance signal be learnt, and signal frequency or amplitude are sent out It is impossible to well adapt to after changing.Based on this, also need to study the online filtering method of special impulse disturbances.

It is superimposed with the signal curve of impulse disturbances, at interference position, curve creates jump, during no pulse interference, bent Line relative smooth, that is, the pace of change of curve is relatively steady.Therefore, according to this feature, impulse disturbances can be identified and filter Remove.It is believed that the increment size approximately equal of adjacent double sampling.When being superimposed with impulse disturbances in signal, then can destroy adjacent two The approximately equalised condition of increment size of secondary sampling, thus can identify the position of impulse disturbances by the relation of double sampling increment size Putting, using the approximately equalised condition of increment twice, estimating disturbed front signal value, thus reaching the mesh filtering impulse disturbances 's.

The present invention by being studied it is proposed that a set of bag to class magnetic grid hydraulic cylinder integrated displacement sensor Signal Pretreatment Filter the Signal Pre-Processing Method with pulse signal filtering function containing DC component, be class magnetic grid hydraulic cylinder integrated displacement sensor The high-precision applications of signal are laid a good foundation.Preprocessed signal quality can be effectively improved, be the hydraulic cylinder of hydraulic actuation mechanism Displacement measurement provides reliable guarantee, has weight to improving the hydraulic cylinder displacement measurements such as Electrical hydrostatic actuator, single rod asymmetric cylinder The actual application value wanted.

Brief description

Fig. 1 is the different frequency signals high-pass filtering analogous diagram that the present invention contains DC component.

Fig. 2 is the signal graph that the present invention contains impulse disturbances.

Fig. 3 is the signal graph after pulse bandwidth filtering of the present invention.

Specific embodiment

DC component filters

For sensor response, the minimum operation speed such as requiring is V_Lmin(mm/s), piston rod tooth pitch is S_PT(mm), For guaranteeing the quality of signal, according to double ten indexs, wave filter is examined, thus obtained high-pass filter passband cutoff frequency Rate is：ω_CHp=2 π V_Lmin/S_PT.Obtained high-pass filter amplitude versus frequency characte A under this frequency_H(ω_CHp) and phase-frequency characteristicMeet following condition respectively.

-10°≤φ_H(ω_CHp)≤10°.

For the performance of distinct high-pass filter, it is also to be understood that the stopband cut-off frequency ω of dawn wave filter_CHr.As set stopband Cut-off frequency amplitude attenuation is 10%, then stopband cut-off frequency meets following condition.

A_H(ω_CHr)=20lg0.1=-20.

Wherein, A_H(ω_CHr) it is the amplitude versus frequency characte under the stopband cut-off frequency of wave filter；ω_CHrStopband for wave filter Cut-off frequency.

To this high-pass filter, to be described from second-order system.Typical transmission function is shown below.

Wherein, H (s) is high pass filter function；A_kFor transmission function gain；T₁For time constant 1；T₂For the time Constant 2.

Three unknown number A are had in above-mentioned transmission function_k、T₁、T₂, a demand goes out corresponding unknown number, you can determine high-pass filtering The transmission function of device.The condition that should meet in view of high-pass filter, the amplitude of transmission function and phase angle should meet with lower section Journey.

By above equation, solve A_k、T₁、T₂, you can determine the transmission function of high-pass filter.For checking high pass filter Different frequency signals containing DC component are emulated, are seen Fig. 1 by the validity of ripple device.By Fig. 1 it is apparent that Signal has a larger time delay of ratio in the starting stage, increases over time, wave filter progresses into steady-working state, Under this state, high-pass filter can effectively filter out DC component.And the time delay of starting stage, result from DC component step defeated Enter.Therefore, high-pass filter enters steady-working state is the premise that DC component filters.For guaranteeing that high-pass filter stablizes work Make, before sensor smooth working, need to have certain preheating time, the big I of preheating time is by the amplitude of DC component and transmission Corresponding construction parameter determination in function.

Impulse disturbances filter

When not containing impulse disturbances in sensor signal, its expression formula such as following formula：

If the frequency acquisition of this signal is f_A, then in t_iThe signal in moment with the variable quantity of previous moment is.

The general term of variable quantity is：

In above formula, as n ω/(2f_A) very little when, Δ f_so(t_i) then can very little, in front and back signal amplitude twice can regard as even Continuous change.In view of higher hamonic wave frequency n generally within 10, and fundamental frequency signal ω and piston rod scale tooth pitch S_PTAnd sensing Device maximum operating speed V_LmaxRelevant, generally also for finite value.On this basis, as long as frequency acquisition f_ASufficiently large, you can to make Δ f_so(t_i) very little.

According to the general term formula of increment, can release in frequency acquisition f_AUnder, the increment general term formula of increment is：

Due to n ω/(2f_A) very little, as n ω/(2f_A)<When 0.1, adjacent incremental difference twice can be less than A_n/(50).n ω/(2f_A) less when, adjacent incremental difference twice can become geometry stage speed reduce.Therefore, as n ω/(2f_A) very little when, can Think the increment size approximately equal of adjacent double sampling.When being superimposed with impulse disturbances in signal, then can destroy and adjacent adopt twice The approximately equalised condition of increment size of sample, thus can identify the position of impulse disturbances by the relation of double sampling increment size, Using the approximately equalised condition of increment twice, estimate disturbed front signal value, thus reaching the purpose filtering impulse disturbances.Cause This, in t_i+1/f_AMoment, shown in corresponding impulse disturbances filtering algorithm following formula：

In above formula, f_so(t_i) it is t_iThe response of moment sensor；Δf_so(t_i)=f_so(t_i)-f_so(t_i-1/f_A) it is t_iMoment The response increment of sensor；Δf_so(t_i+1/f_A)=f_so(t_i+1/f_A)-f_so(t_i) it is t_i+1/f_AThe response of moment sensor increases Amount；δ_TsFor the recognition threshold of impulse response, due to adjacent increment twice under normal circumstances can be approximately considered equal, therefore, such as Fruit has pulse to occur, then have large jump.If setting the minimum amplitude of pulse as the 1/10, δ of normal response amplitude_TsCan It is set to 1+1/10.

For verifying the validity of impulse disturbances filtering algorithm, done by superposition random pulses in typical Chrip signal Disturb the data input as algorithm, the output tried to achieve is the signal after impulse disturbances filter, and the effect of whole algorithm is as schemed 2nd, shown in Fig. 3.

Particular embodiments described above, has been described in detail to the purpose invented, technical scheme and beneficial effect, Be should be understood that the specific embodiment that the foregoing is only the present invention, be not limited to the present invention, all in the present invention Spirit and principle within, any modification, equivalent substitution and improvement done etc., should be included in protection scope of the present invention it Interior.

Claims (4)

1. a species magnetic grid hydraulic cylinder integrated displacement sensor Signal Pre-Processing Method it is characterised in that：Initially with high pass filter Ripple device filters DC component；Again the position of impulse disturbances is identified by the relation of double sampling increment size, using increment twice Approximately equalised condition, estimates disturbed front signal value, filters impulse disturbances it is achieved that full rate high accuracy filters online.

2. a species magnetic grid hydraulic cylinder integrated displacement sensor Signal Pre-Processing Method according to claim 1, its feature It is：DC component is filtered using high-pass filter, before commencing signal is processed, preheating high-pass filter feeds them in advance Steady-working state, the size of preheating time is by the corresponding construction parameter determination in the amplitude and transmission function of DC component.

3. a species magnetic grid hydraulic cylinder integrated displacement sensor Signal Pre-Processing Method according to claim 1, its feature It is：Under high-frequency signal acquisition condition, signal amplitude twice can regard consecutive variations as in front and back, when being superimposed with arteries and veins in signal During punching interference, then can destroy the approximately equalised condition of increment size of adjacent double sampling, thus can pass through double sampling increment size The position to identify impulse disturbances for the relation, using the approximately equalised condition of increment twice, estimate disturbed front signal value, from And realize the online filtering of full rate high accuracy.

4. a species magnetic grid hydraulic cylinder integrated displacement sensor Signal Pre-Processing Method according to claim 3, its feature It is, shown in corresponding impulse disturbances filtering algorithm following formula：

$f_{so}\left(t_i+\frac{1}{f_A}\right)=\left\{\begin{array}{cc}{f}_{so}\left(t_i\right)+{\mathrm{\&Delta;f}}_{so}\left(t_i\right),& h\left(t_i\right)\&GreaterEqual;{\mathrm{\&delta;}}_{Ts}\\ f_{so}(t_i+\frac{1}{f_A}),& h\left(t_i\right)<{\mathrm{\&delta;}}_{Ts}\end{array}\right.$

$h\left(t_i\right)=\frac{\left|f_{so}\left(t_i\right)\right|+\left|{\mathrm{\&Delta;f}}_{so}\left(t_i\right)\right|}{\left|f_{so}\left(t_i\right)\right|+\left|{\mathrm{\&Delta;f}}_{so}(t_i+\frac{1}{f_A})\right|}$

In above formula, f_so(t_i) it is t_iThe response of moment sensor；Δf_so(t_i)=f_so(t_i)-f_so(t_i-1/f_A) it is t_iMoment senses The response increment of device；Δf_so(t_i+1/f_A)=f_so(t_i+1/f_A)-f_so(t_i) it is t_i+1/f_AThe response increment of moment sensor；δ_Ts For the recognition threshold of impulse response, due to adjacent increment twice under normal circumstances can be approximately considered equal, therefore, if there are arteries and veins Go out existing, then have large jump；If setting the minimum amplitude of pulse as the 1/10, δ of normal response amplitude_Ts1+1/ can be set to 10.