Detector column period synchronization system based on scanning angle and control method

Abstract

According to the scanning angle-based detector column period synchronization system and the control method, a high-precision angle measurement element and an angle resolving circuit are used for resolving the scanning angle in real time, and column period synchronization signals required by detector imaging are generated according to a fixed angle interval, so that the scanning angle and the detector imaging column period are synchronized; the geometric imaging precision of the scanning imaging camera is greatly improved, the scanning control difficulty is reduced, and the image resolution precision and the geometric positioning precision of the scanning imaging camera are improved.

Description

Technical Field

[0001] The invention relates to a detector array periodic synchronization system and a control method based on a scanning angle, belonging to the technical field of large-field infrared remote sensing. Background Art

[0002] Within the effective imaging field of view, scanning imaging cameras usually use a scanning mechanism to perform uniform scanning at a fixed scanning speed, and the detector is exposed for imaging at a fixed column period. The column period is required to be consistent with the time of the instantaneous field of view scanned by the scanning mechanism, so that a good target image can be obtained. For scanning angle and image synchronization, a scanning control circuit usually generates a scanning start position synchronization pulse and a series of angular position pulses according to the current scanning angle, and sends them to the video processing circuit. The video processing circuit collects the current image position pulse as the starting point of the current scanning cycle imaging, and at the same time loads the angular position information represented by the position pulse into the image data at the current moment.

[0003] In this synchronization mode, on the one hand, due to the very high requirements for the scanning speed accuracy of the scanning mechanism, the processing, assembly and testing of the scanning mechanism itself and its control circuit have brought very great technical difficulties and high development costs. In the actual control system, due to the influence of factors such as processing, assembly, wear and vibration interference, the scanning speed accuracy is difficult to guarantee, resulting in a certain deviation between the actual scanning speed and the ideal scanning speed. As a result, within a fixed column cycle time, there is a certain difference between the angle scanned by the scanning mechanism and the instantaneous field of view of the camera. The column cycle signal of the existing scanning camera is usually generated by a video processing circuit. The accuracy of the column cycle signal depends on the accuracy of the circuit crystal oscillator, which can generally reach the nanosecond level, which is much higher than the scanning field of view accuracy. This causes a certain deviation between the actual scanning time of the instantaneous field of view angle and the column cycle of the detector, which will ultimately lead to a decrease in the actual sampling resolution and geometric accuracy of the image.

[0004] On the other hand, in the scanning angle position recording method, the scanning control circuit sends a scanning position signal to the video processor. After receiving the scanning position signal, the video processor records the scanning position information and the current image data as a reference for subsequent image positioning. Under this position information recording method, it is affected by the limited number of pulses and the transmission recording delay factors, resulting in low position recording accuracy and large delay, which reduces the image positioning accuracy.

[0005] Therefore, the conventional method of synchronizing the scanning angle with the column period has relatively low geometric accuracy and positioning accuracy for the image, and there is no relevant report on the method and device for setting the column period synchronization based on the scanning angle. Summary of the invention

[0006] The technical problem solved by the present invention is: in view of the lack of content in the current prior art regarding a method and device for setting column period synchronization based on a scanning angle, a detector column period synchronization system and control method based on a scanning angle are proposed.

[0007] The present invention solves the above technical problems by the following technical solutions:

[0008] A detector array period synchronization system based on scanning angle, comprising a scanning control circuit, a scanning mechanism, an amplifying transmission mechanism, an angle measuring element, an angle solving circuit, and a video processing circuit;

[0009] A scanning control circuit generates a scanning control signal according to the scanning task requirements and sends the scanning control signal to the scanning mechanism;

[0010] The scanning mechanism receives the scanning control signal sent by the scanning control circuit and scans the target at a constant speed according to the preset speed in the scanning control signal;

[0011] an amplifying transmission mechanism, connected to the rotating shaft of the scanning mechanism as an input stage, moving at the same preset speed as the rotating shaft of the scanning mechanism, and an output stage driven by the input stage to move according to a preset proportional factor;

[0012] An angle measuring element measures and amplifies the angle information of the output stage of the transmission mechanism and sends it to the angle solving circuit;

[0013] An angle calculation circuit receives angle information for real-time calculation, generates column period synchronization signals according to preset angle intervals, and sends them to the video processing circuit;

[0014] The video processing circuit adopts an external trigger imaging mode and receives a column period synchronization signal sent by an angle solving circuit to perform external trigger imaging, thereby ensuring that the field of view scanned within the detector imaging column period is synchronized with the instantaneous field of view of the scanning imaging camera.

[0015] The relationship between the imaging column period and the scanning angle information is:

[0016] T n =(θ n -θ n-1 ) / V s =IFOV / V s ;

[0017] Where, T n is the imaging column period, θ n-1 is the imaging period T n The starting scanning angle, θ n The period T n The end scanning angle, V sis the scanning speed, and IFOV is the instantaneous field of view of the scanning imaging camera to ensure the resolution and geometric accuracy of the image scanned by the scanning imaging camera.

[0018] Each column periodic synchronization signal generates a corresponding column periodic synchronization signal according to a preset angle difference of n*IFOV. The detector performs a magnified measurement of the scanning angle by a preset proportional factor n of the amplifying transmission mechanism, thereby reducing the influence of the measurement error of the angle measuring element on the detector scanning angle measurement.

[0019] The relationship between the preset scale factor n, preset range and preset angle difference of the amplifying transmission mechanism is:

[0020] n*IFOV*(5‰)>2″

[0021] When the relationship between the preset scale factor n, the preset range and the preset angle difference of the amplifying transmission mechanism meets the requirements, the detector meets the image resolution and geometric accuracy higher than 5‰ indicators.

[0022] The angle measuring element adopts a high-precision photoelectric encoder or an inductive synchronizer to measure the angle, and the measurement error is less than 2" to ensure the resolution and geometric accuracy of the image scanned by the scanning imaging camera.

[0023] The transmission amplification mechanism adopts gear transmission or chain transmission to realize proportional amplification of the rotation speed of the scanning mechanism. The angle measuring element is placed at the rear stage of the amplification transmission mechanism and is installed coaxially with the rear stage rotating shaft to measure the movement angle of the rear stage rotating device.

[0024] The angle calculation circuit is used to calculate the angle signal output by the angle measuring element in real time, and to generate a column period synchronization signal required for detector imaging according to a fixed angle interval corresponding to the angular resolution of the scanning imaging camera.

[0025] The scanning control circuit includes a torque motor, a scanning motion curve planning module, a controller module, a linear drive module, a scanning mechanism, an angle measurement and solving module, and an induction synchronizer;

[0026] The scanning motion curve generation module is used to generate scanning motion instructions that meet the scanning motion curve corresponding to the scanning task. The controller module compares the scanning motion instructions output by the scanning motion curve planning module in real time, generates a torque instruction and sends it to the linear drive module;

[0027] The angle measurement and resolution module generates an excitation signal according to the scanning task, collects the sine and cosine analog quantities sent by the induction synchronizer to perform shaft angle resolution, and generates scanning angle information in real time and sends it to the scanning motion curve planning module, controller module, and linear drive module;

[0028] The linear drive module forms a drive signal according to the scanning angle information and the torque command and sends it to the torque motor, and the scanning mechanism is driven by the torque motor;

[0029] The inductive synchronizer scans the scanning mechanism in real time to obtain real-time scanning angle information.

[0030] The angle measuring element adopts any one of a photoelectric encoder, a rotary transformer and an inductive synchronizer. The inductive synchronizer adopts a circular inductive synchronizer, which is made of a winding engraved on a 0.1 mm thick copper-clad plate or by a chemical etching method, and is fixed on a 10 mm thick disc-shaped metal or fiberglass substrate and coated with a layer of anti-static shielding film.

[0031] A scanning control method implemented by a detector array periodic synchronization system, comprising:

[0032] The scanning control circuit generates a scanning control signal according to the scanning task requirements, and controls the scanning mechanism to scan at a uniform speed according to the ideal scanning speed V1;

[0033] The input stage of the amplifying transmission mechanism is set as the rotating shaft of the scanning mechanism, and the ideal scanning speed V1 is set as the preset speed, and after being amplified by the preset proportional factor n, the output stage is driven to move according to the actual scanning speed V2;

[0034] The angle measuring element measures the output stage angle information in real time, and the angle solving circuit solves the rotation angle of the output stage in real time, and generates a column period synchronization signal according to a fixed angle difference;

[0035] The video processing circuit controls the detector to perform imaging according to the column period synchronization signal, so as to synchronize the field of view scanned within the detector imaging column period with the instantaneous field of view angle of the scanning imaging camera.

[0036] The advantages of the present invention compared with the prior art are:

[0037] (1) The present invention provides a detector column period synchronization system and control method based on scanning angle, which adopts a transmission amplification mechanism to amplify the scanning speed by a certain factor, collects the amplified angle through a high-precision angle measurement element, and solves the scanning angle position information through an angle solving circuit, and generates the column period synchronization signal required for detector imaging according to a fixed angle position interval equal to the sampling resolution, which serves as the basis for synchronous imaging of the detector, thereby realizing high-precision synchronization between the scanning position and the detector imaging column period;

[0038] (2) The present invention amplifies the scanning angular velocity and detects the amplified angle signal through a high-precision angle measuring element, which greatly improves the scanning angle measurement accuracy. It also uses the fixed angle period of the real-time scanning angle as the direct synchronization source of the detector imaging column period signal, thereby achieving strict synchronization between the scanning time corresponding to the scanning instantaneous field of view angle and the detector imaging period, improving the image sampling resolution accuracy and geometric positioning accuracy of the scanning imaging camera, and at the same time achieving strict synchronization between the scanning angle and the detector imaging position, eliminating the scanning angle loading delay, and improving the image processing and geometric positioning accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 A simplified schematic block diagram of the detector array periodic scanning example device provided by the invention;

[0040] Figure 2 A schematic diagram of the relationship between the column period signal and the scanning angle position provided by the invention;

[0041] Figure 3 A schematic diagram of the stator and rotor structure provided for the invention;

[0042] Figure 4 A diagram of the relative motion of the stator and rotor provided for the invention;

[0043] Figure 5 The signal conditioning circuit diagram of the induction synchronizer provided for the invention;

[0044] Figure 6 The principle diagram of tracking amplitude discrimination axis angle solution provided for the invention;

[0045] Figure 7 A timing diagram of the scanning cycle, scanning start signal and scanning segment number provided for the invention;

[0046] Figure 8 A block diagram of the scanning control structure provided for the invention;

[0047] Fig. 9 A control block diagram based on position feedback provided for the invention;

[0048] Fig.10 A block diagram of the video processing circuit provided for the invention; DETAILED DESCRIPTION

[0049] A detector column period synchronization system and control method based on scanning angle, which utilizes a high-precision angle measuring element and an angle solving circuit to solve the scanning angle in real time, and generates a column period synchronization signal required for detector imaging at fixed angle intervals, thereby realizing synchronization of the scanning angle with the detector imaging column period, and realizing scanning imaging and scanning control that greatly improves the geometric imaging accuracy of the scanning imaging camera, thereby improving the image resolution accuracy and geometric positioning accuracy of the scanning imaging camera.

[0050] The detector array period synchronization system based on the scanning angle includes:

[0051] It includes a scanning control circuit, a scanning mechanism, an amplifying transmission mechanism, an angle measuring element, an angle solving circuit, and a video processing circuit;

[0052] A scanning control circuit generates a scanning control signal according to the scanning task requirements and sends the scanning control signal to the scanning mechanism;

[0053] The scanning mechanism receives the scanning control signal sent by the scanning control circuit and scans the target at a constant speed according to the preset speed in the scanning control signal;

[0054] an amplifying transmission mechanism, connected to the rotating shaft of the scanning mechanism as an input stage, moving at the same preset speed as the rotating shaft of the scanning mechanism, and an output stage driven by the input stage to move according to a preset proportional factor;

[0055] An angle measuring element measures and amplifies the angle information of the output stage of the transmission mechanism and sends it to the angle solving circuit;

[0056] An angle calculation circuit receives angle information for real-time settlement, generates a column period synchronization signal according to a preset angle difference and sends it to a video processing circuit;

[0057] The video processing circuit adopts an external trigger imaging mode and receives the column period synchronization signal sent by the angle solving circuit for imaging, so as to ensure that the field of view scanned within the imaging column period of the detector is synchronized with the instantaneous field of view of the scanning imaging camera.

[0058] The relationship between the column period synchronization signal and the scanning angle information is:

[0059] T n =(θ n -θ n-1 ) / V s =IFOV / V s ;

[0060] Where, T n is the imaging column period, θ n-1 is the imaging period T n The starting scanning angle, θ n The period T n The end scanning angle, V s is the scanning speed, IFOV is the instantaneous field of view of the scanning imaging camera; when the scanning speed V s If the imaging column period T is still fixed, the length of each column period will no longer be equal. n Imaging sampling will lead to a decrease in image resolution and geometric accuracy. Therefore, by using the actual angular position θn As an imaging column periodic synchronization signal, it can effectively ensure the resolution and geometric accuracy of the image scanned by the scanning imaging camera.

[0061] Each column periodic synchronization signal generates a corresponding column periodic synchronization signal according to a preset angle difference of n*IFOV. The detector performs a magnified measurement of the scanning angle by a preset proportional factor n of the amplifying transmission mechanism, thereby reducing the influence of the measurement error of the angle measuring element on the detector scanning angle measurement.

[0062] The relationship between the preset scale factor n, the preset range and the preset angle difference of the amplifying transmission mechanism is:

[0063] n*IFOV*(5‰)>2″

[0064] When the relationship between the preset scale factor n, the preset range and the preset angle difference of the amplifying transmission mechanism meets the requirements, the detector meets the image resolution and geometric accuracy higher than 5‰ indicators.

[0065] The angle measuring element uses a high-precision photoelectric encoder or inductive synchronizer for angle measurement, and the measurement error is less than 2" to ensure the resolution and geometric accuracy of the image scanned by the scanning imaging camera.

[0066] The transmission and amplification mechanism adopts gear transmission or chain transmission to proportionally amplify the rotation speed of the scanning mechanism. The angle measuring element is located at the rear stage of the amplification transmission mechanism and is coaxially installed with the rear stage rotating shaft to measure the movement angle of the rear stage rotating device.

[0067] The angle calculation circuit is used to calculate the angle signal output by the angle measuring element in real time, and to generate the column period synchronization signal required for detector imaging according to the fixed angle interval corresponding to the angular resolution of the scanning imaging camera.

[0068] The scanning control method implemented by the detector array period synchronization system comprises the following specific steps:

[0069] The scanning control circuit generates a scanning control signal according to the scanning task requirements, and controls the scanning mechanism to scan at a uniform speed according to the ideal scanning speed V1;

[0070] The input stage of the amplifying transmission mechanism is set as the rotating shaft of the scanning mechanism, and the ideal scanning speed V1 is set as the preset speed, and after being amplified by the preset proportional factor n, the output stage is driven to move according to the actual scanning speed V2;

[0071] The angle measuring element measures the output stage angle information in real time, and the angle solving circuit solves the rotation angle of the output stage in real time, and generates a column period synchronization signal according to a fixed angle difference;

[0072] The video processing circuit controls the detector to perform imaging according to the column period synchronization signal, so as to synchronize the field of view scanned within the detector imaging column period with the instantaneous field of view angle of the scanning imaging camera.

[0073] The following is further described in conjunction with the accompanying drawings and preferred embodiments of the specification:

[0074] In the current embodiment, the detector column period synchronization system adopts a transmission amplification mechanism to amplify the scanning speed by a certain factor, collects the amplified angle through a high-precision angle measurement element, and solves the scanning angle position information by an angle solving circuit, and generates the column period synchronization signal required for detector imaging according to a fixed angle position interval as the basis for the synchronous imaging of the detector, so as to realize the high-precision synchronization of the scanning position and the detector imaging column period, specifically:

[0075] The detector column period synchronization method and device based on scanning angle is to add a set of column period generation device on the basis of the original scanning mechanism, which is composed of an amplification transmission mechanism, a high-precision angle measuring element, and a high-speed angle solution;

[0076] Among them, the transmission amplification mechanism adopts gear transmission or chain transmission to realize proportional amplification of the rotation speed of the scanning mechanism, and realize the angle measurement capability with an angle resolution better than 1 / 5; the high-precision angle measurement element has an angle measurement accuracy better than 2", which is placed in the rear stage of the transmission mechanism and installed coaxially with the rear stage rotating shaft to measure the movement angle of the rear stage rotating device;

[0077] High-speed angle calculation, used to calculate the angle signal output by the angle measuring element in real time with high speed and high precision, and generate the column period synchronization signal required for detector imaging according to the fixed angle interval corresponding to the camera angular resolution;

[0078] like Figure 1 As shown, a method and device for setting a column period based on a scanning angle are composed of a scanning control circuit, a scanning mechanism, an amplifying transmission mechanism, an angle measuring element, and an angle solving circuit.

[0079] In the existing scanning imaging camera, the ideal scanning speed V=FOV / T(° / s) can be calculated according to the scanning field of view FOV(°) and the linear segment scanning time T(s) of the scanning imaging camera. The scanning control circuit controls the scanning mechanism to drive the scanning mirror or the optical system to scan at a uniform speed according to the ideal scanning speed V. The actual scanning speed of the scanning mechanism is V1, and V1 fluctuates around V in value. (V1-V) / V=δ is defined as the scanning nonlinearity. The imaging column period T0=IFOV (instantaneous field of view) / V is a fixed value, and the object field of view IFOV'=T0*V1 scanned by the scanning mechanism within the actual column period time, so IFOV≠IFOV', which will inevitably lead to a decrease in the resolution of the camera and a decrease in the corresponding geometric positioning accuracy. Therefore, the value of δ is required to be as small as possible, usually requiring δ<5‰, in order to ensure the imaging quality of the scanning imaging camera and the geometric accuracy of the image. This brings very great technical difficulties and high development costs to the processing, assembly and testing of the scanning mechanism itself and its control circuit.

[0080] In the present invention, the scanning control circuit 110 controls the scanning mechanism 120 to scan at a uniform speed V1, the input stage of the amplifying transmission mechanism 130 is the rotating axis of the scanning mechanism, which moves at the same speed, and the amplifying transmission mechanism drives the output stage to move at a speed of V2=n*V1 according to a fixed proportional factor n. The angle measuring element 140 adopts a high-precision photoelectric encoder or an inductive synchronizer for real-time measurement of the output stage angle information. The angle solving circuit 150 solves the rotation angle of the output stage in real time and generates a column period synchronization signal according to a fixed angle difference n*IFOV. The video processing circuit 160 adopts an externally triggered imaging mode and controls the detector to perform imaging according to the received column period synchronization signal, so as to achieve strict synchronization between the field of view scanned within the imaging column period of the detector and the instantaneous field of view of the camera.

[0081] like Figure 2 As shown, the corresponding relationship between the column period synchronization signal and the scanning angle position is given. In the figure, θ2-θ1=θ3-θ2=θ4-θ3=…=θn-θn-1=IFOV. Due to the scanning speed deviation, T1, T2, …, Tn in the figure are not necessarily equal. There is a certain time difference between them, but it does not affect the resolution and geometric accuracy of the image. Therefore, the requirements for the linearity of the actual scanning speed within the column period time such as T1 and T2 can be relaxed, which greatly reduces the scanning control accuracy and only increases the difficulty of the timing control of the video processing circuit.

[0082] This embodiment directly performs an amplified measurement on the scanning angle as a reference for the detector imaging column period, wherein the measurement error of the high-precision photoelectric code disk or inductive synchronizer is less than 2″. As long as n*IFOV*(5‰)>2″ after amplification by the transmission amplifier mechanism is ensured, the image resolution and geometric accuracy are higher than 5‰.

[0083] The real-time detector uses an angle measuring element to measure the magnified scanning angle, generates a column period synchronization signal at a fixed angle interval, and controls the detector imaging to be completely synchronized with the scanning field of view. The scanning mechanism drives the input stage of the amplifying transmission mechanism to scan at a uniform speed according to the set scanning speed. The amplifying transmission mechanism uses an amplifying mechanism with a certain transmission ratio n to amplify the scanning speed, and drives the output stage to drive the output stage angle measuring element to move at n times the scanning speed, thereby reducing the impact of the measurement error of the angle measuring element on the system angle position measurement.

[0084] The angle solving circuit solves the angle position signal at a high speed and outputs the column period synchronization signal according to the fixed angle period. The video processing circuit adopts the external synchronization working mode and controls the detector integration imaging according to the column period synchronization signal, thus realizing the high-precision synchronization of the angle and the detector integration time.

[0085] Furthermore, the scanning control circuit needs to have extremely high position and rate control performance, that is, the swing scanning control circuit is required to have high rate control accuracy within the scanning linear segment to ensure the scanning linearity index.

[0086] The scanning control system adopts a position servo control scheme. This scheme uses a torque motor as an actuator and a high-precision circular induction synchronizer as a feedback device to form a position closed-loop control circuit. From a functional perspective, its scanning controller can be divided into four parts: an angle measurement and calculation module, a scanning motion curve planning module, a controller module, and a linear drive module. Its control structure is as follows: Figure 8 shown.

[0087] Among them, the scanning motion curve generation module is used to generate a scanning motion curve that meets the system requirements, and then provide the position closed loop for servo control;

[0088] The controller module is the core of the entire scanning control system. It compares the angular position command given by the scanning motion curve planning module and the current position measurement value provided by the angle measurement and solution module in real time, calculates the torque command through the corresponding control and compensation algorithm, and sends it to the motor drive module;

[0089] The angle measurement and resolution module provides a stable excitation signal for the high-precision circular induction synchronizer, collects sine and cosine analog quantities for shaft angle resolution, and places the scanning angle information on the angular position information bus in real time for application by other modules;

[0090] The linear drive module receives the driving torque command from the controller, collects the angular position information of the current scanning mechanism from the angular position information bus, and gives the motor drive signal through the mechanical / electrical phase matching calculation and pulse width modulation circuit.

[0091] The scanning controller adopts a control method based on position feedback. The control scheme based on position feedback uses a high-precision induction synchronizer as a position feedback device and selects a torque motor as an actuator; the entire system is based on DSP to achieve full digital implementation of the control law. Its control principle is as follows Fig. 9 shown.

[0092] The scheme first generates a position command that satisfies the system motion law by DSP. The induction synchronizer is used to measure the motion position of the reflector and transmits it to the DSP processor through the data bus. In one control cycle of DSP, it first filters and corrects the output of the shaft angle solver circuit through the feedback correction unit, and then obtains the deviation between the current position and the predetermined position. Then, the correction torque command is calculated through the previous control law, and the PWM channel inside the DSP is modulated and transmitted to the motor amplifier. It can be seen that if the position feedback loop has sufficient servo stiffness, each interference torque will be effectively attenuated through the feedback loop, and the position servo accuracy of the scanning mirror can be guaranteed. In addition, since the system is based on the full digital implementation of closed-loop control of DSP, it can conveniently perform open-loop adjustment on the position waveform generation unit and the feedback correction unit according to the system position closed-loop characteristics, thereby improving the system's rate stability accuracy and position control accuracy.

[0093] Angle measurement element is a key component of the angle measurement system. The performance of the angle position sensor directly affects the performance indicators of the entire angle measurement system, such as working stability, conversion speed and measurement accuracy. Currently, the commonly used angle sensors include three types: photoelectric encoders, resolvers and induction synchronizers.

[0094] Photoelectric encoder is a kind of device that converts the mechanical geometric displacement on the output shaft into pulse or digital angle through photoelectric conversion. It has the advantages of high accuracy, wide measurement range, small size and light weight, but poor vibration and impact resistance, and is not suitable for long life requirements.

[0095] The rotary transformer is a multi-pole electromagnetic induction position detection component. It has the characteristics of resistance to harsh environments, low installation accuracy requirements, fast running speed, strong anti-electromagnetic interference ability, and low cost, but its accuracy is not high enough;

[0096] The induction synchronizer is a high-precision angular position sensor based on the principle of electromagnetic induction. Its working principle is similar to that of a rotary transformer, but it has more pole pairs and has a full-cycle error compensation function, so the component has high precision. It also has the advantages of a rotary transformer, such as relatively low installation accuracy requirements, vibration and impact resistance, and stable performance, and is suitable for high precision and long life requirements.

[0097] The manufacturing process of the circular induction synchronizer is to first use a 0.1 mm thick copper-clad plate to carve or chemically etch the winding, then fix it to a 10 mm thick disc-shaped metal or fiberglass substrate, and then apply a layer of anti-static shielding film. The gap between the stator and the rotor is 0.2 to 0.3 mm. The rotor winding is a single-phase continuous fan-shaped distribution. Each guide vane is equivalent to a pole of the motor, and the distance between adjacent guide vanes is one pole pitch. The stator winding is arranged in fan-shaped segments, and the pole pitch is the same as that of the rotor. The linear induction synchronizer is similar to the disc type structure. The difference is that it consists of a fixed scale and a sliding scale, and the windings are arranged at equal distances. This type of winding is generally called a printed circuit winding, and its structure is as follows Figure 3 shown.

[0098] The rotor winding is made into a continuous type, such as Figure 1 As shown, it consists of an active conductor 1 , an inner end 2 and an outer end 3 .

[0099] The stator winding is made into segments, which is called segmented winding. The winding consists of 2K groups of conductors, which belong to phase A and phase B respectively, and K is called the number of groups in one phase. Each group consists of M effective conductors and corresponding ends connected in series. The groups on the same phase are connected into one phase by connecting wires. The effective conductors of the stator and rotor are both radial.

[0100] There are three ways to lead out the rotor winding: the first is to lead it out directly by cable; the second is to use the slip ring installed on the rotor base plate and then lead it out through the brush; the third is to use the transformer installed on the inner circle of the stator and rotor base plates to lead it out in a contactless way.

[0101] The circular induction synchronizer works on the principle of electromagnetic coupling. By applying an excitation signal to the rotor, a changing current flows through its effective conductor, causing a changing magnetic field. At the same time, the effective conductor on the stator is in this changing magnetic field, and an induced voltage is also generated. The frequency of the induced voltage is the same as the excitation frequency of the rotor, and its amplitude is related to the relative position of the stator effective conductor and the rotor effective conductor.

[0102] like Figure 4 As shown in the figure, the relative positions of the stator and rotor effective conductors at different times during the rotation of the rotor are described, where the distance between the center lines of every two effective conductors is called a pole pitch.

[0103] Assuming the angular frequency of the excitation signal input by the rotor is ω, according to the principle of electromagnetic induction, the stator also induces a voltage signal of the same frequency, recorded as E*sin(ω). The value of E will change with the relative position of the effective conductors of the stator and rotor windings.

[0104] Depend on Figure 4 (1) shows that at this time, the positions of the effective conductors of the stator and rotor windings overlap each other, and E reaches its maximum value, which is denoted by E mWhen the rotor rotates to Figure 4 (2) When the stator effective conductor is exactly in the middle of the two rotor effective conductors, E = 0. Then the rotor continues to rotate to Figure 4 (3) When the position is shown, E reaches the negative maximum value, E = -E m ; After the rotor rotates half a pole pitch, Figure 4 (4) At position, E=0.

[0105] In the stator and rotor Figure 4 (4), the rotor will reach the position shown in 2(1) again after another half cycle, at which time the amplitude of the stator output induced voltage changes by one cycle.

[0106] Therefore, from the above analysis, it can be known that when the rotor rotates two pole pitches relative to the stator, the amplitude of the induced voltage output by the stator changes by one cycle, that is, the mechanical angle rotates by two pole pitches, and the electrical angle changes by one cycle. Therefore, for circular induction synchronizers with different pole numbers, the mechanical angle corresponding to one electrical angle cycle is different. A pole pitch of a 720-pole circular induction synchronizer is 0.5 degrees, that is, the amplitude of the stator induction output electrical signal changes by one cycle, and the mechanical angle of the rotor rotates by one degree; a pole pitch of a 360-pole circular induction synchronizer is 1 degree, that is, the amplitude of the stator induction output electrical signal changes by one cycle, and the mechanical angle of the rotor rotates by 2 degrees.

[0107] Since the distance between the stator A and B phase windings differs by (n+1 / 2) pole pitches, the output electrical signal amplitudes of the two phase windings differ by 90 degrees. That is, if the electrical angle caused by the current rotor rotation is θ e , set the output voltage amplitude of phase A winding to E m *SIN(θ e ), then the output voltage amplitude of phase B winding is E m *COS(θ e ). As long as the current output voltage E of each channel A and B phase is obtained A 、E B , the electrical angle of each channel can be calculated. The specific calculation process is as follows:

[0108] Assume the current electrical angle of the channel is θ e , the maximum output voltage of each phase is E m , then the current A and B phase output voltage E A =E M SIN(θ E ), E B =E M COS(θ E ). After A / D conversion using a single chip microcomputer, the two-phase signal E A and E BDivide to get the tangent value of the detected electrical angle:

[0109] So the measured electrical angle is:

[0110] Apply an excitation signal to the rotor continuous winding, and determine the current electrical angle θ by measuring the output voltage of the stator A and B two-phase windings. e , the mechanical angle of the rotor's rotation relative to the stator can be obtained, thus achieving the purpose of angle measurement.

[0111] In the angle calculation circuit:

[0112] The overall framework of the absolute induction synchronizer angle measurement system should be composed of hardware platforms including dual-channel circular induction synchronizer, excitation module, signal conditioning module, shaft angle digital conversion module, data processing module and interface module, as well as related software platforms. In the excitation module, the orthogonal oscillator generates the excitation signal and excites the induction synchronizer through the power amplifier. In addition to completing the necessary pre-amplification, main amplifier and bandpass filtering functions, the signal conditioning module also needs to complete the amplitude balance adjustment and phase matching adjustment functions of the two-phase output signal of the induction synchronizer. The shaft angle digital conversion module selects an integrated tracking shaft angle converter to complete the shaft angle digital conversion task.

[0113] Generation of excitation signal:

[0114] The main function of the excitation circuit is to provide 1 absolute circular induction synchronizer excitation signal and 2 tracking shaft angle converter reference signals.

[0115] According to the manual of the induction synchronizer, the angular measurement frequency of the component is 10Khz, the fine channel excitation voltage (peak-to-peak) is 3.2v, and the coarse channel excitation voltage (peak-to-peak) is 0.9v.

[0116] Therefore, an orthogonal oscillator is used as the oscillation source of the excitation circuit, and a dedicated driver chip for the induction synchronizer is selected, which can simultaneously provide two signals with a 90-degree phase difference as the excitation signal and the reference signal respectively. The oscillation frequency can be set by two external capacitors, the output frequency range is 400Hz to 20kHz, and the output voltage amplitude can be adjusted up to 7.5V, which can meet the excitation requirements of the induction synchronizer.

[0117] Preamplifier circuit:

[0118] Since the voltage coupling coefficient of the induction synchronizer is very small (typical values ​​are between 1 / 500 and 1 / 100), the induction voltage signal output by the induction synchronizer is very weak, with a peak value often ranging from tens of microvolts to several millivolts. It is easily affected by its own or external noise, so the signal must be amplified several thousand times and the noise must be strictly suppressed. Therefore, the preamplifier is a key part of the conditioning circuit. This low-noise, high-gain situation puts high demands on the design of the preamplifier circuit for the output signal of the induction synchronizer, that is, using the sensor and amplifier noise analysis theory to model the noise of the induction synchronizer output stage and the preamplifier circuit input stage, so as to analyze the noise coefficient and optimal source resistance of the corresponding induction synchronizer output signal, and use this as a basis to select a reasonable amplifier device to match the noise with the induction synchronizer.

[0119] Main amplifier circuit:

[0120] The main function of the operational amplifier in the main amplifier circuit is to perform secondary amplification of the signal, which is used to complete the gain adjustment and amplitude matching fine-tuning functions. Its unit gain bandwidth is 2.5MHz, and the noise voltage caused by the amplifier is Unoise=3*10 -5 V.

[0121] Bandpass filter circuit:

[0122] In order to eliminate the harmonic components and out-of-band noise in the excitation signal and the reference signal and make the output more stable, the signal needs to be filtered before the excitation signal enters the solver chip. This system designs a bandpass filter with a center frequency of 10kHz and a bandwidth of 2kHz.

[0123] Phase shift circuit:

[0124] The tracking shaft angle converter needs to input a signal with the same frequency and phase as the carrier signal as a reference. Since the phase shift of the coarse and fine channels is not exactly the same, two independent phase shift circuits are designed in the excitation circuit to provide independent reference signals to the coarse and fine channels respectively.

[0125] Shaft-angle conversion chip: The shaft-angle digital conversion circuit is the most important part of the angle measurement system circuit. It converts the sine-cosine two-phase analog signal output by the inductive synchronizer into a digital signal. Its conversion accuracy and speed directly affect the performance of all aspects of the angle measurement system. A tracking amplitude-detection shaft-angle digital conversion integrated chip is used. It is characterized by a tracking amplitude-detection shaft-angle solution method. On the basis of the amplitude-detection solution principle, a closed-loop feedback loop is introduced to further improve the robustness of the amplitude-detection shaft-angle solution to interference signals. This method has been widely used due to its advantages such as fast solution speed, high accuracy, and insensitivity to signal amplitude noise. Its solution principle is as follows: Figure 6 As shown:

[0126] For the output angle φ, after the sine / cosine multiplier, the AC error signal can be obtained:

[0127]

[0128] The error can be obtained by phase-sensitive demodulation with the reference signal. The error is then stabilized through a closed-loop circuit to complete the precise shaft angle solution.

[0129] After the parameter matching is completed, the shaft angle solution accuracy can be optimized. After experimental verification, the 16-bit angle encoding LSB bit can remain stable, indicating that the angle measurement resolution of the solution circuit is 0.11", the angle indication accuracy is 0.11" under the condition of the lowest data bit stability, and the angle repeatability is better than 1", which can meet the control requirements.

[0130] According to the technical requirements, the angle calculation circuit outputs the scanning start signal and the column cycle synchronization signal to the video processing circuit. The timing relationship is as follows: Figure 7 shown.

[0131] When the scanning circuit gives the first pulse, the precise spatial position of the scanning mirror is calibrated. The subsequent pulses are all equal-angle pulses. The spatial angles corresponding to the subsequent pulses can be deduced in sequence, and the target can be accurately located and captured.

[0132] Video processing circuit:

[0133] like Fig.10 As shown, the video processing circuit is composed of a focal plane circuit unit, a signal processing unit and a data encoding unit.

[0134] The focal plane circuit includes four parts: power supply processing part, timing drive part, bias voltage generation part, analog signal pre-conditioning part. The functions of the focal plane circuit are:

[0135] 1) Power processing part: mainly to filter 10 kinds of electricity such as ±9VA, ±6VA, +5VD, etc. of the secondary power input, and convert them into the voltage required by the focal plane circuit;

[0136] 2) Bias voltage generation circuit: According to the technical requirements of the detector for bias voltage, it generates the low-noise, high-precision bias voltage required for the normal operation of the detector to ensure the quality of the detector power supply;

[0137] 3) Clock driving circuit: According to the detector's requirements for timing signals, the timing control signal generated by the signal processing circuit is shaped and filtered to generate the timing driving signal required for the detector to work; the digital-to-analog converter driving signal generated by the receiving signal processing circuit is used to drive multiple digital-to-analog converters; the flag signal output by the detector is driven and sent to the signal processing circuit.

[0138] 4) Analog signal pre-conditioning circuit: Buffer and impedance match the detector output signal according to the detector's load requirements and the characteristics of the detector's output signal; re-condition the matched signal to meet the input dynamic range of the analog-to-digital converter.

[0139] The signal processing unit is responsible for analog-to-digital conversion, pixel correction, odd-number-of-pixel geometric position correction, and data synthesis of analog signals, and sends the synthesized data to the data encoding circuit through the LVDS level interface; according to the search second start signal and column cycle synchronization signal sent by the data encoding unit, the working timing required by the detector is generated, and the sampling period of the detector is controlled to be strictly synchronized with the column period provided by the scanning control circuit.

[0140] The data encoding unit receives the scanning start signal and column cycle synchronization signal sent by the scanning control circuit and provides them to the signal processing unit. The image data sent by the signal processing unit is corrected, and the corrected data is encoded according to the specified format and sent to the data transmission subsystem and the onboard pre-processing subsystem;

[0141] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

[0142] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

Claims

1. A detector array period synchronization system based on scanning angle, characterized in that: It includes a scanning control circuit, a scanning mechanism, an amplifying transmission mechanism, an angle measuring element, an angle solving circuit, and a video processing circuit; A scanning control circuit generates a scanning control signal according to the scanning task requirements and sends the scanning control signal to the scanning mechanism; The scanning mechanism receives the scanning control signal sent by the scanning control circuit and scans the target at a constant speed according to the preset speed in the scanning control signal; an amplifying transmission mechanism, connected to the rotating shaft of the scanning mechanism as an input stage, moving at the same preset speed as the rotating shaft of the scanning mechanism, and an output stage driven by the input stage to move according to a preset proportional factor; An angle measuring element measures and amplifies the angle information of the output stage of the transmission mechanism and sends it to the angle solving circuit; An angle calculation circuit receives angle information for real-time calculation, generates column period synchronization signals according to preset angle intervals, and sends them to the video processing circuit; The video processing circuit adopts an external trigger imaging mode and receives a column period synchronization signal sent by an angle solving circuit to perform external trigger imaging, thereby ensuring that the field of view scanned within the detector imaging column period is synchronized with the instantaneous field of view of the scanning imaging camera.

2. The detector array period synchronization system based on scanning angle according to claim 1, characterized in that: The relationship between the imaging column period and the scanning angle information is: T n =(θ n -θ n-1 ) / V s =IFOV / V s ; Where, T n is the imaging column period, θ n-1 is the imaging period T n The starting scanning angle, θ n The period T n The end scanning angle, V s is the scanning speed, and IFOV is the instantaneous field of view of the scanning imaging camera to ensure the resolution and geometric accuracy of the image scanned by the scanning imaging camera.

3. The detector array period synchronization system based on scanning angle according to claim 2, characterized in that: Each column periodic synchronization signal generates a corresponding column periodic synchronization signal according to a preset angle difference of n*IFOV. The detector performs a magnified measurement of the scanning angle by a preset proportional factor n of the amplifying transmission mechanism, thereby reducing the influence of the measurement error of the angle measuring element on the detector scanning angle measurement.

4. The detector array period synchronization system based on scanning angle according to claim 2, characterized in that: The relationship between the preset scale factor n, preset range and preset angle difference of the amplifying transmission mechanism is: n*IFOV*(5‰)>2″ When the relationship between the preset scale factor n, the preset range and the preset angle difference of the amplifying transmission mechanism meets the requirements, the detector meets the image resolution and geometric accuracy higher than 5‰ indicators.

5. The detector array period synchronization system based on scanning angle according to claim 2, characterized in that: The angle measuring element adopts a high-precision photoelectric encoder or an inductive synchronizer to measure the angle, and the measurement error is less than 2" to ensure the resolution and geometric accuracy of the image scanned by the scanning imaging camera.

6. The detector array period synchronization system based on scanning angle according to claim 2, characterized in that: The transmission amplification mechanism adopts gear transmission or chain transmission to realize proportional amplification of the rotation speed of the scanning mechanism. The angle measuring element is placed at the rear stage of the amplification transmission mechanism and is installed coaxially with the rear stage rotating shaft to measure the movement angle of the rear stage rotating device.

7. The detector array period synchronization system based on scanning angle according to claim 2, characterized in that: The angle calculation circuit is used to calculate the angle signal output by the angle measuring element in real time, and to generate a column period synchronization signal required for detector imaging according to a fixed angle interval corresponding to the angular resolution of the scanning imaging camera.

8. The detector array period synchronization system based on scanning angle according to claim 2, characterized in that: The scanning control circuit includes a torque motor, a scanning motion curve planning module, a controller module, a linear drive module, a scanning mechanism, an angle measurement and solving module, and an induction synchronizer; The scanning motion curve generation module is used to generate scanning motion instructions that meet the scanning motion curve corresponding to the scanning task. The controller module compares the scanning motion instructions output by the scanning motion curve planning module in real time, generates a torque instruction and sends it to the linear drive module; The angle measurement and resolution module generates an excitation signal according to the scanning task, collects the sine and cosine analog quantities sent by the induction synchronizer to perform shaft angle resolution, and generates scanning angle information in real time and sends it to the scanning motion curve planning module, controller module, and linear drive module; The linear drive module forms a drive signal according to the scanning angle information and the torque command and sends it to the torque motor, and the scanning mechanism is driven by the torque motor; The inductive synchronizer scans the scanning mechanism in real time to obtain real-time scanning angle information.

9. The detector array period synchronization system based on scanning angle according to claim 8, characterized in that: The angle measuring element adopts any one of a photoelectric encoder, a rotary transformer and an inductive synchronizer. The inductive synchronizer adopts a circular inductive synchronizer, which is made of a winding engraved on a 0.1 mm thick copper-clad plate or by a chemical etching method, and is fixed on a 10 mm thick disc-shaped metal or fiberglass substrate and coated with a layer of anti-static shielding film.

10. A scanning control method implemented by the detector array period synchronization system according to claim 9, characterized in that include: The scanning control circuit generates a scanning control signal according to the scanning task requirements, and controls the scanning mechanism to scan at a uniform speed according to the ideal scanning speed V1; The input stage of the amplifying transmission mechanism is set as the rotating shaft of the scanning mechanism, and the ideal scanning speed V1 is set as the preset speed, and after being amplified by the preset proportional factor n, the output stage is driven to move according to the actual scanning speed V2; The angle measuring element measures the output stage angle information in real time, and the angle solving circuit solves the rotation angle of the output stage in real time, and generates a column period synchronization signal according to a fixed angle difference; The video processing circuit controls the detector to perform imaging according to the column period synchronization signal, so as to synchronize the field of view scanned within the detector imaging column period with the instantaneous field of view angle of the scanning imaging camera.

Images