CN103591967A - Optical Chirp Signal Generation Method for Optical Servo System Spectrum Curve Test - Google Patents

Abstract

A method for generating an optical Chirp signal for optical servo system frequency spectrum curve tests comprises the following steps: employing a collimator to generate a target capable of being imaged in a photoelectric theodolite imaging sensor, and enabling the target of the collimator can be clearly imaged in a photoelectric theodolite; enabling a rotation arm to drive the collimator to swing according to a preset speed and a preset amplitude to generate the optical Chirp signal; and finishing calculation processing on a photoelectric theodolite frequency spectrum curve by a master control computer. The provided method for the optical Chirp signal for the optical servo system frequency spectrum curve tests helps to provide input signals for the optical servo system frequency spectrum curve tests, and on the base, corresponding algorithm and means are utilized for finishing tests on the optical servo system frequency spectrum curve, and therefore the method has important meaning on indoor evaluation of photoelectric theodolite tracking performance.

Description

Optical Chirp Signal Generation Method for Optical Servo System Spectrum Curve Test

technical field

The invention relates to the field of precision detection of photoelectric measuring equipment, in particular to an optical Chirp signal generation method used for spectrum curve testing of an optical servo system.

Background technique

The tracking performance of the photoelectric theodolite servo system is an important index of the dynamic performance of the photoelectric theodolite, and it is an index that must be tested when the photoelectric theodolite leaves the factory. At present, the indoor detection methods of the dynamic performance of the photoelectric theodolite servo system mainly include optical dynamic target detection and equivalent sinusoidal guidance detection. These two methods test the tracking performance in the time domain, which can only reflect the performance indicators of the equipment at specific speed and acceleration values, and cannot evaluate the overall tracking performance of the photoelectric theodolite.

In order to solve this problem, it is proposed to test the spectrum characteristic curve of the photoelectric theodolite, and then use the amplitude-frequency curve part of the spectrum curve to indirectly complete the overall tracking performance evaluation of the photoelectric theodolite. The theoretical basis of this evaluation method is that the photoelectric theodolite servo control system is a linear system with single input and single output. According to classical control theory, differential equations, transfer functions, and frequency characteristics can all characterize the motion laws of the system. In order to test the spectral characteristics of the photoelectric theodolite, the method is to use the equipment to generate a dynamic target as an input signal, the photoelectric theodolite tracks the target and outputs the tracking error, and uses the spectrum curve processing method to process the data to obtain the photoelectric theodolite spectrum curve. In order to measure the curve accurately, it is required that the input signal can fully excite all modes or characteristics of the photoelectric theodolite servo system. From the perspective of spectrum analysis, it means that the spectrum of the input signal must be sufficient to cover the spectrum of the system.

In order to complete the test of the spectrum curve of the photoelectric theodolite, the data samples required for algorithm processing include accurate and measurable input and output data. The input signal of the photoelectric theodolite must be an optical signal to ensure that it can be imaged on the imaging sensor. The output signal is the tracking error of the servo control system of the photoelectric measuring equipment.

In order to solve this problem, a continuous linear frequency modulation model, that is, a Chirp signal model is proposed to generate an input signal. And the Chirp signal was generated on the existing detection equipment—the dynamic target, and the tracking test was carried out by using multiple types of photoelectric theodolites. However, due to the relationship between the dynamic target space model, the generated Chirp signal model is a series of harmonic signal superposition mode, and the output signal of the photoelectric theodolite is also a harmonic signal superposition mode. At present, due to the lack of an effective method for separating the harmonics of the Chirp signal, it is impossible to accurately obtain the spectrum curve of the photoelectric theodolite servo system.

Contents of the invention

The invention solves the technical problem that the photoelectric theodolite spectrum curve cannot be tested in the prior art, and provides an optical chirp signal generation method that can meet the spectrum test requirements and is used for the spectrum curve test of the optical servo system.

In order to solve the problems of the technologies described above, the technical solution of the present invention is specifically as follows:

A method for generating an optical Chirp signal for optical servo system spectrum curve test, comprising the following steps:

Step 1, the collimator produces a target that can be imaged on the photoelectric theodolite imaging sensor, so that the target of the collimator can be clearly imaged on the photoelectric theodolite;

Step 2, establishing a unified time reference between the optical Chirp signal generating device and the photoelectric theodolite through the time system terminal;

Establish serial communication between the main control computer and the photoelectric theodolite, use the main control computer to set the amplitude, signal envelope, and chirp slope parameters of the optical Chirp signal, and then send the parameters to the servo controller through RS422 serial port communication;

After the servo controller performs control processing, it generates a PWM signal and sends it to the servo driver;

The servo driver drives the torque motor to rotate, so that the rotating arm swings around the precision shaft system;

The 24-bit absolute photoelectric encoder completes the precise measurement of the angular position and angular velocity of the rotating arm;

According to the performance index of the detected photoelectric theodolite, calculate the signal envelope, chirp slope and amplitude value of the optical Chirp signal according to the optical Chirp signal generation formula, so that the generated optical Chirp signal can cover the working angular velocity range of the detected photoelectric theodolite;

Through the signal envelope, linear frequency modulation slope and amplitude value of the optical Chirp signal in the main control computer, and start the device to work;

Make the rotating arm drive the collimator to swing according to the set speed and amplitude, and generate an optical Chirp signal;

Step 3, the photoelectric theodolite tracks the optical Chirp signal, and sends the tracking error information to the main control computer through the serial communication interface, and the main control computer completes the calculation and processing of the photoelectric theodolite spectrum curve.

In the above technical solution, the spectral range generated by the collimator can cover visible to long-wave infrared bands.

In the above technical solution, the collimator is a bromine tungsten lamp.

In the above technical solution, the target plate of the collimator is a star point hole, a reticle or a reticle.

In the above technical solution, in step 2, the performance indicators of the detected photoelectric theodolite include: working angular velocity range with guaranteed accuracy, tracking accuracy, and maximum angular velocity and angular acceleration.

The present invention has following beneficial effect:

The optical Chirp signal generation method for the optical servo system spectrum curve test proposed by the present invention can provide input signals for the photoelectric theodolite servo system spectrum curve test, and on this basis, the photoelectric theodolite servo system spectrum curve can be completed by using corresponding algorithms and means The test is of great significance to the indoor evaluation of the tracking performance of the photoelectric theodolite.

Description of drawings

The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments.

Fig. 1 is a schematic structural diagram of an optical Chirp signal generating device equipped in the method of the present invention.

Fig. 2 is a schematic diagram of the trajectory of the optical Chirp signal generated in the method of the present invention.

The reference signs in the figure represent:

1-collimator, 2-lifting support frame, 3-rotating arm, 4-platform table, 5-24-bit absolute photoelectric encoder, 6-torque motor, 7-conductive ring, 8-precision shafting, 9 -Photoelectric theodolite, 10-power supply communication cable, 11-control cabinet, 12-main control computer, 13-servo controller, 14-time system terminal, 15-servo driver, 16-DC regulated power supply.

Detailed ways

In order to complete the test of the spectral characteristic curve of the photoelectric theodolite servo system, the present invention proposes a new optical Chirp signal generation method, which uses the generated optical Chirp signal as an input signal for the spectral characteristic curve test.

The present invention will be described in detail below in conjunction with the accompanying drawings.

The optical chirp signal generating method for optical servo system spectrum curve test of the present invention comprises the following steps:

Step 1, equip a set of optical Chirp signal generation device, as shown in Figure 1. Including parallel light tube 1, liftable support frame 2, rotating arm 3, platform table top 4, 24-bit absolute photoelectric encoder 5, torque motor 6, conductive ring 7, precision shaft system 8, power supply and communication cable 10, control cabinet 11 , Main control computer 12, servo controller 13, time system terminal 14, servo driver 15, DC regulated power supply 16. The collimator 1 is used to generate a target that can be imaged on the photoelectric theodolite imaging sensor. The light source of the collimator 1 adopts a bromine tungsten lamp, and the spectral range produced can cover the visible to the long-wave infrared band. The target plate of the collimator 1 can be selected from a star point hole, a crosshair, a reticle, and the like. The liftable support frame 2 is used for fixing the collimator 1 . According to the different heights of the photoelectric theodolite 9, the height and direction of the liftable support frame 2 can be adjusted to ensure that the target of the collimator 1 can be clearly imaged on the photoelectric theodolite 9.

Step 2, fixing the measured photoelectric theodolite 9 on the platform table 4 . Through the time system terminal 14, a unified time reference is established between the optical Chirp signal generating device and the photoelectric theodolite 9. And establish serial communication between the main control computer 12 and the photoelectric theodolite 9. Use the main control software in the main control computer 12 to set the amplitude, signal envelope and chirp slope parameters of the optical Chirp signal, and then send the parameters to the servo controller 13 through RS422 serial communication. After the servo controller 13 performs control processing, it generates a PWM signal and sends it to the servo driver 15 . The servo driver 15 drives the torque motor 6 to rotate, so that the rotating arm 3 swings around the precision shaft system 8 . The 24-bit absolute photoelectric encoder 5 completes the precise measurement of the angular position and angular velocity of the rotating arm 3 . According to the precision-guaranteed working angular velocity range, tracking accuracy, and performance indicators such as the highest angular velocity and angular acceleration of the detected photoelectric theodolite, the signal envelope, linear frequency modulation slope and amplitude value of the optical Chirp signal are calculated according to the optical Chirp signal generation formula, so that the generated The optical Chirp signal can cover the working angular velocity range of the detected photoelectric theodolite. Through the signal envelope, linear frequency modulation slope and amplitude value of the optical Chirp signal in the main control computer 12, and start the device to work. The optical Chirp signal can be generated by making the rotating arm 3 drive the collimator 1 to swing according to the set speed and amplitude.

Step 3, the photoelectric theodolite 9 tracks the optical Chirp signal, and sends the tracking error information to the main control computer 12 through the serial communication interface. The main control software in the main control computer 12 completes the calculation and processing of the spectrum curve of the photoelectric theodolite.

Description of working principle:

The reason why the Chirp signal is selected as the input signal of the photoelectric theodolite 9 spectrum curve test is that the spectrum of the Chirp signal can fully cover the spectrum of the photoelectric theodolite servo system. This is the first condition for the frequency spectrum of the photoelectric theodolite servo system to be tested.

The signal generation principle of the optical Chirp signal generating device is that the rotating arm 3 swings around the precision shaft system 8 under the control of the main control computer 12, and drives the collimator 1 to swing to generate Chirp signals. The swing formula of the collimator can be described by formula (1) in the time domain.

s(t)=Asin((α+βt)t), 0≤t≤T (1)

Among them, α is the signal envelope, β is the signal linear frequency modulation slope, A is the amplitude value of the signal, and T is the signal duration. For example, when α=0.2513, β=0.0013, and A=1, the target motion trajectory of the optical Chirp signal generating device is shown in Figure 2 . The motion trajectory is used as the input signal, and the tracking error of the photoelectric theodolite is used as the output signal. The type, signal envelope, and chirp slope of the output signal are similar to the input signal, only the amplitude is different.

In the above-mentioned embodiment of the optical Chirp signal generation method for optical servo system spectrum curve test of the present invention:

Collimator 1 adopts Cassegrain structure, diameter Φ100mm, focal length 1000mm, light source adopts bromine tungsten lamp, spectrum band covers visible light 0.4μm～0.8μm, medium wave infrared 3μm～5μm, long wave infrared 8μm～12μm; lifting support frame 2 , rotating arm 3, platform table 4 and other structures are customized by Changchun Aopu Optoelectronics Co., Ltd.; the 24-bit absolute photoelectric encoder 5 adopts the absolute photoelectric encoder developed by Changchun Optical Machinery, with an accuracy of 1″ and a resolution of 0.077″; torque The motor 6 adopts the product of Chengdu Precision Motor Factory; the conductive ring 7 adopts the conductive ring product of Hangzhou Quansheng Company; the precision shaft system 8 is customized by Changchun Aupu Optoelectronics Company; the main control computer 12 mainly includes an industrial computer with a PCI slot, a display, Input device, serial communication card, etc. The serial communication card adopts Advantech's CP-134U four-serial port acquisition card. Parameters such as the amplitude, signal envelope and chirp frequency of the optical Chirp signal generating device are selected according to the performance index of the photoelectric theodolite servo system, and are set through the main control computer 12 .

Apparently, the above-mentioned embodiments are only examples for clear description, rather than limiting the implementation. For those of ordinary skill in the art, other changes or changes in different forms can be made on the basis of the above description. It is not necessary and impossible to exhaustively list all the implementation manners here. And the obvious changes or changes derived therefrom are still within the scope of protection of the present invention.

Claims (5)

1. for an optics Chirp signal creating method for optical servo system spectrum curve test, it is characterized in that, comprise the following steps:

Step 1, by parallel light tube produce can imaging on electro-optic theodolite imaging sensor target, make the target of parallel light tube can be on electro-optic theodolite blur-free imaging;

Step 2 is set up benchmark unified time between optics Chirp signal generating apparatus and electro-optic theodolite by time terminal;

Set up the serial communication between main control computer and electro-optic theodolite, utilize main control computer that amplitude, signal envelope, the chirp slope parameter of optics Chirp signal are set, then by RS422 serial communication by parameter to servo controller;

Servo controller produces pwm signal after controlling and processing and delivers to servo-driver;

Servo driver drives torque motor rotates, and pivot arm is swung around precision bearing system;

24 absolute optical encoders complete the position, angle of pivot arm and the precision measurement of angular velocity;

According to the performance index of detected light electro-theodolite set, according to optics Chirp signal, generate signal envelope, chirp slope and the range value of formula calculating optical Chirp signal, make the optics Chirp signal generating can cover detected light electro-theodolite set operating angle velocity range;

By signal envelope, chirp slope and range value at main control computer optics Chirp signal, and starting outfit work;

Make pivot arm drive parallel light tube to swing according to setting speed and amplitude, produce optics Chirp signal;

Step 3, electro-optic theodolite is followed the tracks of optics Chirp signal, and tracking error information exchange is crossed to serial communication interface is sent to main control computer, by main control computer, completes the computing to electro-optic theodolite spectrum curve.

2. the optics Chirp signal creating method for the test of optical servo system spectrum curve according to claim 1, is characterized in that, the spectral range that described parallel light tube produces can cover as seen to long wave infrared region.

3. the optics Chirp signal creating method for the test of optical servo system spectrum curve according to claim 2, is characterized in that, described parallel light tube is bromine tungsten filament lamp.

4. the optics Chirp signal creating method for the test of optical servo system spectrum curve according to claim 1, is characterized in that, the Target Board of described parallel light tube is asterism hole, crosshair or graticule.

5. according to the optics Chirp signal creating method for the test of optical servo system spectrum curve described in any one in claim 1-4, it is characterized in that, in step 2, the performance index of detected light electro-theodolite set comprise: protect precision operating angle velocity range, tracking accuracy, and the highest angular velocity, angular acceleration.

Images