Soft subdivision method of moire frange signal of grating

The following describes the implementation of the method of the present invention in combination with specific hardware and software:

Referring to Figure 3, the high-speed ARM processor LPC1769 (U1) is used to complete various data processing and implement subdivision algorithms. The two sine and cosine signals of A and B are respectively connected to the FA and FB terminals of the zero-crossing detector composed of the voltage comparator chip LM211D (U2). After the A and B square wave signals output by U2 pass through the direction identification circuit, they are output The signal terminal D is connected to the P1.16 pin of the ARM processor LPC1769 (U1). The square wave signal of channel A is connected to the CAP0.0 pin and EINT1 pin of LPC1769 (U1) at the same time, and is connected to the signal latch terminal Lock of the CPLD chip (U3). The two subdivided pulse signals are respectively output from the PWM1 and PWM2 ends, and PWM1 and PWM2 are respectively connected to the IA and IB ends of the count and latch circuit inside the CPLD chip (U3). The signal enable terminal En of the counting and latch circuit inside the CPLD chip (U3) is connected to the P1.17 pin of the ARM processor LPC1769 (U1), and the data output terminals D15~D0 of the CPLD chip (U3) are connected to the ARM processor LPC1769 in turn (U1) P0.17~P0.2 are connected.

Taking N=10 and using the third-order autoregressive model AR(3) for prediction as an example, the implementation process of the present invention will be described in detail (see Figure 4 and Figure 5):

In the main program of U1, set the initial value of the initial sampling times of the prediction model k=0, the sampling flag Flag=0, and set the interrupt priority of CAP0 higher than the EINT1 interrupt, and then wait for the interrupt state. The reshaped square-wave grating signal of channel A triggers the CAP0 interrupt and EINT1 interrupt of U1, and the CAP0 interrupt is given priority.

When the number of interrupts k<10, in the CAP0 interrupt service routine of U1, only collect t k Value operation, in the EINT1 interrupt service routine, because Flag=0, exit without doing any operation.

When the number of interrupts k = 10, in the CAP0 interrupt service routine of U1, proceed as follows:

①Collect t 11 value.

②Calculation:

Δt k = T k+1 -t k , Y k =Δt k , K=8,9,10 (4)

Here, y k It is an intermediate variable set for the convenience of calculation.

③Using the 10th, 9th, and 8th data of the model, calculate the predicted value of the 11th data of the model:

Δ t ^ i + 1 = L ( Δt i + 1 | Δt i - 1 , Δ i - 2 , . . . , Δt i - N ) = X j = 1 p a j Δt i - j + 1 - - - ( 2 )

And assign Δ t ^ 11 = y ^ 11 .

④Set the P1.17 signal high, collect t from the P0.17~P0.2 port 10 Subdivision error at time e 10 , And calculate t 11 Number of subdivided pulses output at a time:

P 11 =Δs/Q-e 10 (6)

⑤Output P in time 11 Two subdivision pulse signals set the PWM controller.

⑥ After k=11 and Flag=1, open interrupt and return.

When the number of interrupts k=11, in the CAP0 interrupt service routine of U1, proceed as follows:

(I) Start the PWM controller to output the subdivision pulse signal

(II) Assign value k=12, collect t 12 value.

(III) Move the data window to the right and assign t j = T j+1 , J=1, 2,..., 11.

(IV) Perform the same operations as above ②~⑥ in sequence.

When Flag=1, in the EINT1 interrupt service routine of U1, proceed as follows:

(I) Calculation:

Δt k = T k+1 -t k , Y k =Δt k , K=1, 2,..., 10 (7)

(II) Calculate the estimate of sample self-covariance function:

Δ t ^ i + 1 = L ( Δt i + 1 | Δt i - 1 , Δ i - 2 , . . . , Δt i - N ) = X j = 1 p a j Δt i - j + 1 - - - ( 2 )

(III) Use:

Δ t ^ i + 1 = L ( Δt i + 1 | Δt i - 1 , Δ i - 2 , . . . , Δt i - N ) = X j = 1 p a j Δt i - j + 1 - - - ( 2 )

(I) Calculation: