Control method of probe with ultrasonic phased array transducers in hinge array

Abstract

The disclosure relates to a control method of a probe with ultrasonic phased array transducers in a hinge array, and belongs to the technical field of ultrasonic detecting. The control method includes the steps: firstly, fixing a part under test, making a central piezoelectric array element of piezoelectric array elements for the ultrasonic phased array transducers in the hinge array make contact with a surface of the part under test, and then fixing a fixed support; before detection is started, driving the hinge array through voice coil motors to make the piezoelectric array elements completely fit the surface of the part under test, wherein the number of the piezoelectric array elements is 2N+1 (N=1, 2, 3, 4 and 5), and different values of N are selected according to a size of the part under test; with the value of pressure of the central piezoelectric array element as a standard and difference values between values of pressures of other piezoelectric array elements and the value of pressure of the central piezoelectric array element as control signals of respective corresponding voice coil motor coils, controlling output rods to drive the hinge array; keeping the values of pressures of all the piezoelectric array elements consistent by means of an incremental digital PID control method; and then realizing deflecting and focusing of ultrasonic waves by means of a time delay rule for ultrasonic detecting, thereby detecting parts under test with planar or curved surfaces.

Claims

1. A control method of a probe, wherein the probe comprises ultrasonic phased array transducers in a hinge array, and the control method comprises the following steps: fixing a part under test, making a central piezoelectric array element of piezoelectric array elements contact with a surface of the part under test, and then fixing a fixed support; symmetrically arraying and fixedly connecting voice coil motor magnetic cylinders onto the fixed support; before detection is started, driving the hinge array through voice coil motors to make the piezoelectric array elements completely fit the surface of the part under test, wherein a number of the piezoelectric array elements is 2N+1, where N=1, 2, 3, 4 and 5, and different values of N are selected according to a size of the part under test; configuring the piezoelectric array elements as pressure sensors using a piezoelectric effect to collect all values of pressures, F.sub.1, F.sub.2, . . . , F.sub.N, . . . , F.sub.2N and F.sub.2N+1; by using difference values e, as control signals of respective corresponding voice coil motor coils, i=1, 2, . . . , (N−1), (N+1), . . . , 2N, (2N+1), e.sub.i=(F.sub.i-F.sub.N), F.sub.N being the value of pressure of the central piezoelectric array element, controlling output rods to drive the hinge array; controlling the values of pressures of all the piezoelectric array elements i, i=1, 2, . . . , (N−1), (N+1), . . . , 2N and (2N+1), by an incremental digital PID control method: $y_i\left(t\right)=K_p\left\{e_i\left(t\right)+\frac{T}{T_i}\underset{j=0}{\overset{t}{.Math.}}{e}_i\left(j\right)+\frac{T_d}{T}\left[e_i\left(t\right)-e_i\left(t-1\right)\right]\right\}$ $y_i\left(t-1\right)=K_p\left\{e_i\left(t-1\right)+\frac{T}{T_i}\underset{j=0}{\overset{t-1}{.Math.}}{e}_i\left(j\right)+\frac{T_d}{T}\left[e_i\left(t-1\right)-e_i\left(t-2\right)\right]\right\}$ wherein K.sub.p is a proportionality coefficient, T.sub.i is an integral time constant, T.sub.d is a differential time constant, T is a sampling cycle, t is a current time, y(t) is an output of a controller, e.sub.i(t) is an input of a sampling controller at a time t, e.sub.i(t−1) is a sampling input at a time t−1, e.sub.i(t−2) is a sampling input of a time t−2; obtaining an incremental digital PID difference equation: h(t)=Δy(t)=y(t)−y(t−1)=K.sub.p[e(t)−e(t−1)]+K.sub.Ie(t)+K.sub.D[e(t)−2e(t−1)+e(t−2)], wherein K.sub.I is an integral coefficient, K.sub.D is a differential coefficient, Δy(t) is a difference of the output of the controller, and h(t) is an incremental digital PID difference function; making the difference values of the values of pressures of all the piezoelectric array elements and the value of pressure of the central piezoelectric array element less than an error allowable value 10.sup.−3 Newton by the incremental digital PID control method, that is, considering that the values of pressures of all the piezoelectric array elements are kept consistent finally within an error allowable range, namely, F.sub.1=F.sub.2= . . . =F.sub.N= . . . =F.sub.2N=F.sub.2N+1; and then realizing deflecting and focusing of ultrasonic waves by a time delay rule for ultrasonic detecting, thereby detecting the part under test with a planar or curved surface.

Description

BRIEF DESCRIPTION OF FIGURES

(1) FIG. 1 is a schematic diagram of a detecting device with ultrasonic phased array transducers in a hinge array.

(2) FIG. 2 is a schematic structural diagram of a voice coil motor.

(3) FIG. 3 is a block diagram of control over piezoelectric array elements of ultrasonic phased array transducers in a hinge array.

(4) Reference numerals for parts in Figures: 1—fixed support, 2—voice coil motor, 2a—voice coil motor coil, 2b—voice coil motor magnetic cylinder, 3—output rod, 4—piezoelectric array element, and 5—part under test.

DETAILED DESCRIPTION

(5) The disclosure will be further described in detail below with reference to the accompanying drawings:

(6) A control method of a probe with ultrasonic phased array transducers in a hinge array includes the following steps: firstly, fixing a part under test 5, making a central piezoelectric array element of piezoelectric array elements 4 make contact with a surface of the part under test 5, and then fixing a fixed support 1; symmetrically arraying and fixedly connecting voice coil motor magnetic cylinders 2b onto the fixed support 1; before detection is started, driving the hinge array through voice coil motors 2 to make the piezoelectric array elements 4 completely fit the surface of the part under test 5, wherein the number of the piezoelectric array elements is 2N+1 (N=1, 2, 3, 4 and 5), and different values of N are selected according to a size of the part under test; configuring the piezoelectric array elements 4 as pressure sensors by means of a piezoelectric effect to collect all values of pressures, F.sub.1, F.sub.2, . . . , F.sub.N, . . . , F.sub.2N and F.sub.2N+1; with the value of pressure F.sub.N of the central piezoelectric array element of the piezoelectric array elements 4 as a standard and difference values e.sub.1, e.sub.2, . . . , e.sub.N−1, e.sub.N+1, . . . , e.sub.2N and e.sub.2N+1 between values of pressures of other piezoelectric array elements and the value of pressure F.sub.N of the central piezoelectric array element as control signals of respective corresponding voice coil motor coils 2a, controlling output rods 3 to drive the hinge array; controlling the values of pressures of all the piezoelectric array elements by means of an incremental digital PID control method:

(7) $y_i\left(t\right)=K_p\left\{e_i\left(t\right)+\frac{T}{T_i}\underset{j=0}{\overset{t}{.Math.}}{e}_i\left(j\right)+\frac{T_d}{T}\left[e_i\left(t\right)-e_i\left(t-1\right)\right]\right\}$$y_i\left(t-1\right)=K_p\left\{e_i\left(t-1\right)+\frac{T}{T_i}\underset{j=0}{\overset{t-1}{.Math.}}{e}_i\left(j\right)+\frac{T_d}{T}\left[e_i\left(t-1\right)-e_i\left(t-2\right)\right]\right\}$
wherein K.sub.p is a proportionality coefficient, T.sub.i is an integral time constant, T.sub.d is a differential time constant, T is a sampling cycle, t is a current time, y(t) is an output of a controller, e.sub.i(t) is an input of a sampling controller at a time t, e.sub.i(t−1) is a sampling input at a time t−1, e.sub.i(t−2) is a sampling input of a time t−2, and i=1, 2, . . . , N−1, N+1, . . . , 2N and 2N+1; obtaining an incremental digital PID difference equation: h(t)=Δy(t)=y(t)−y(t−1)=K.sub.p[e(t)−e(t−1)]+K.sub.Ie(t)+K.sub.D[e(t)−2e(t−1)+e(t−2)], wherein K.sub.I is an integral coefficient, K.sub.D is a differential coefficient, Δy(t) is a difference of the output of the controller, and h(t) is an incremental digital PID difference function; making the difference values of the values of pressures of all the piezoelectric array elements and the value of pressure of the central piezoelectric array element less than an error allowable value 10.sup.−3N by means of the incremental digital PID control method, that is, considering that the values of pressures of all the piezoelectric array elements are kept consistent finally within an error allowable range, that is, F.sub.1=F.sub.2= . . . =F.sub.N= . . . =F.sub.2N=F.sub.2N+1; and then realizing deflecting and focusing of ultrasonic waves by means of a time delay rule for ultrasonic detecting, thereby detecting parts under test with planar or curved surfaces.