Piezoelectric driving image motion compensating mirror device and control method

Abstract

The invention relates to the technical field of precision optical instruments and photoelectricity, in particular to a piezoelectric driving image motion compensating mirror device and a control method. The invention provides a piezoelectric driving image motion compensating mirror device. The piezoelectric driving image motion compensating mirror device comprises a connecting bottom plate, the bearing seat is fixedly arranged on the connecting bottom plate; the reflecting mirror is rotatably mounted on the bearing seat and is used for receiving and reflecting the optical light beam; the actuator assembly is used for driving the reflecting mirror to deflect around a preset axis so as to realize image motion compensation; wherein the actuator assembly adopts a driving structure based on strain direct feedback, the actual deflection displacement of the reflecting mirror is indirectly obtained by detecting the strain change of a driving part of the actuator assembly, and closed-loop control is formed based on displacement feedback. According to the invention, the deflection displacement of the reflector is indirectly obtained by detecting the strain of the driving part of the actuator assembly through the actuator assembly, high-precision image motion compensation is realized, and the device is more compact in structure and higher in reliability.

Description

Technical Field

[0001] This invention relates to the fields of precision optical instruments and optoelectronic technology, and more specifically, to a piezoelectric-driven image shift compensation mirror device and control method. Background Technology

[0002] Optical image shift compensation technology plays a crucial role in modern imaging systems, especially in precision optics fields such as high-resolution remote sensing imaging, astronomical observation, and medical imaging. Image shift compensation mirrors achieve image stabilization by precisely controlling the beam direction, and their performance directly affects the resolution and image quality of the imaging system. As optical imaging technology advances towards higher resolution and greater stability, traditional image shift compensation schemes face numerous challenges.

[0003] Currently, image shift compensation mirrors mainly employ mechanical stabilization platforms or direct piezoelectric ceramic drive. While mechanical stabilization platforms offer a larger compensation range, their slow response speed and limited accuracy make them unsuitable for high-speed dynamic image shift compensation. On the other hand, traditional piezoelectric ceramic drive schemes, although offering faster response, exhibit significant nonlinearity, hysteresis, and creep phenomena, severely restricting control accuracy and system stability.

[0004] For example, US Patent US2018356212A1 uses a capacitive sensor for displacement feedback, which improves control accuracy to some extent, but the system is complex and sensitive to the environment, especially in space applications where it is susceptible to temperature changes and radiation interference.

[0005] The image shift compensation mirror system developed by PI GmbH in Germany employs a multi-layer piezoelectric ceramic stacked structure and achieves closed-loop control through a high-precision displacement sensor. However, this system is costly, and the displacement sensor is bulky, making it difficult to apply in space-constrained environments. Hamamatsu Corporation of Japan's solution uses an optical encoder as the position detection element. While it boasts high resolution, its performance significantly degrades under vibration conditions, and its radiation resistance is also insufficient.

[0006] Image motion compensation mirrors used in space remote sensing applications need to cope with extreme environmental conditions. For example, the image motion compensation mirror used by the European Space Agency in an Earth observation project, although employing a complex environmental compensation mechanism, still has potential issues regarding its system reliability and long-term stability. Furthermore, existing technologies largely rely on indirect displacement detection methods, which cannot directly and accurately reflect actual changes in image motion, thus limiting the final compensation accuracy.

[0007] In recent years, with the continuous development of high-resolution Earth observation and astronomical exploration technologies, higher requirements have been placed on image shift compensation accuracy. In satellite remote sensing systems, image shift compensation accuracy directly affects the spatial resolution of images; in astronomical telescopes, the stability of image shift compensation directly affects the quality of observational data. Existing technological solutions are no longer sufficient to meet the stringent requirements of these cutting-edge applications for image shift compensation accuracy, stability, and environmental adaptability.

[0008] Therefore, there is an urgent need for a new type of image shift compensation mirror device that can achieve high-precision, high-stability and fast-response image shift compensation while possessing excellent environmental adaptability and system reliability, thereby promoting the continuous development of precision optical imaging technology. Summary of the Invention

[0009] The purpose of this invention is to provide a piezoelectric-driven image shift compensation mirror device and control method, which solves the problems of existing image shift compensation mirror devices having complex structures, large size, high cost, and limited adaptability and reliability in extreme environments.

[0010] To achieve the above objectives, the present invention provides a piezoelectric driven image shift compensation mirror device, comprising a connecting base plate, a bearing seat, a reflector, and an actuator assembly: The connecting base plate is used to support the overall structure of the device; The bearing housing is fixedly mounted on the connecting base plate; The reflector is rotatably mounted on the bearing seat and is used to receive and reflect optical beams; The actuator assembly is mounted on the bearing housing and connected to the reflector, and is used to drive the reflector to deflect around a preset axis to achieve image shift compensation. The actuator assembly adopts a drive structure based on direct strain feedback. By detecting the strain change of its own drive components, it indirectly obtains the actual deflection displacement of the reflector and forms a closed-loop control based on the displacement feedback.

[0011] In some embodiments, the actuator assembly includes a piezoelectric ceramic stack, a strain gauge, a flexible rotor, a return spring, and a locating pin. The piezoelectric ceramic stack serves as a driving component, used to receive driving voltage and output linear driving force; The strain gauge is mounted on the piezoelectric ceramic stack and is used to detect the strain change of the piezoelectric ceramic stack during the expansion and contraction process in real time, and generate a feedback signal for closed-loop control. The flexible rotor is connected between the piezoelectric ceramic stack and the reflector, and is used to convert the linear motion of the piezoelectric ceramic stack into the deflection motion of the reflector. The reset spring is connected to the flexible rotor and is used to provide a reverse restoring force to the flexible rotor; The positioning pin is disposed between the flexible rotor and the reflector to achieve a positioning connection between the flexible rotor and the reflector.

[0012] In some embodiments, the reflector is connected to the actuator assembly via a central pivot. The actuator assembly drives the central rotating shaft to rotate, thereby causing the reflector to deflect around the central rotating shaft.

[0013] In some embodiments, the circumferential surface of the central rotating shaft is provided with a plurality of annular grooves; The annular groove is used to accommodate the adhesive. The reflector is fixed to the central pivot using adhesive.

[0014] In some embodiments, the connecting base plate is made of a material with a low coefficient of thermal expansion. The connecting base plate and the bearing seats on both sides together form a U-shaped frame structure.

[0015] In some embodiments, the low coefficient of thermal expansion material has a coefficient of thermal expansion of less than 1.5 × 10⁻⁶ in the temperature range of -40°C to +60°C. -6 / ℃.

[0016] In some embodiments, the low coefficient of thermal expansion material includes Invar steel.

[0017] In some embodiments, the piezoelectric ceramic stack adopts a multilayer laminated integrated structure, which is formed by alternating stacking of multilayer piezoelectric ceramic sheets and internal electrodes.

[0018] In some embodiments, the strain gauge is a semiconductor strain gauge with a corresponding strain sensitivity coefficient of not less than 2.0.

[0019] In some embodiments, the flexible rotor employs a flexible structure based on a cross hinge, having at least two symmetrically arranged lever arms: Each of the lever arms is connected to a piezoelectric ceramic stack and a return spring. The middle part of the flexible rotor is connected to the central axis of the reflector through the positioning pin, so that the lever arm deflects around the central axis under the drive of the piezoelectric ceramic stack, converting the linear motion of the piezoelectric ceramic stack into the rotational motion of the reflector.

[0020] In some embodiments, the flexible rotor is made of titanium alloy material; By optimizing the geometric parameters of the lever ratio, lever arm length, and structural thickness, the linear motion of the piezoelectric ceramic stack is converted into the deflection motion of the reflector, and the rotational stiffness is balanced with the system's natural frequency.

[0021] In some embodiments, the apparatus further includes a control system: The control system is electrically connected to the actuator assembly and is used to receive feedback signals from the strain gauge and adjust the driving voltage applied to the piezoelectric ceramic stack based on the difference between the feedback signal and the target deflection command to achieve closed-loop control.

[0022] In some embodiments, the control system mainly includes a signal conditioning circuit, a digital controller, and an actuator drive circuit. The signal conditioning circuit is connected to the strain gauge and is used to receive and process the feedback signal from the strain gauge. The digital controller is connected to the signal conditioning circuit and is used to receive the processed feedback signal, compare it with the target deflection command to generate an error signal, and output a digital control quantity. The actuator drive circuit is connected to the digital controller and the piezoelectric ceramic stack, and is used to convert the digital control quantity into a drive voltage adapted to the piezoelectric ceramic stack, and apply it to the piezoelectric ceramic stack to drive the piezoelectric ceramic stack.

[0023] To achieve the above objectives, the present invention provides a piezoelectric-driven image shift compensation control method, which is implemented using the aforementioned piezoelectric-driven image shift compensation mirror device, and includes the following steps: Obtain the target deflection command for the reflector; A driving voltage is applied to the piezoelectric ceramic stack in the actuator assembly to drive the mirror to deflect. The strain gauge detects the real-time strain of the piezoelectric ceramic stack, and the actual deflection displacement feedback signal of the reflector is obtained based on the real-time strain. The feedback signal of the actual deflection displacement is compared with the target deflection command to generate an error signal; and The driving voltage is adjusted in real time based on the error signal to perform closed-loop control of the deflection of the reflector.

[0024] The piezoelectric-driven image shift compensation mirror device and control method proposed in this invention indirectly obtains the deflection displacement of the reflector by detecting the strain of its own driving component through the actuator assembly, and forms a closed-loop control to drive the reflector to deflect, thereby achieving high-precision image shift compensation. At the same time, the device structure is more compact and the reliability is higher. Attached Figure Description

[0025] The above and other features, properties and advantages of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings and embodiments, in which the same reference numerals always denote the same features, wherein: Figure 1 An overall structural diagram of a piezoelectric-driven image shift compensation mirror device according to an embodiment of the present invention is disclosed; Figure 2 A front view of a piezoelectrically driven image shift compensation mirror device according to an embodiment of the present invention is disclosed; Figure 3 A schematic diagram of the overall structure of a reflector according to an embodiment of the present invention is disclosed; Figure 4 A partial structural diagram of the adhesive filling of a reflector according to an embodiment of the present invention is disclosed; Figure 5 An internal structural diagram of an actuator assembly according to an embodiment of the present invention is disclosed; Figure 6 A schematic diagram illustrating the mirror deflection principle according to an embodiment of the present invention is disclosed; Figure 7 A schematic diagram of a closed-loop feedback circuit according to an embodiment of the present invention is disclosed; Figure 8 A flowchart illustrating the steps of a piezoelectric-driven image shift compensation control method according to an embodiment of the present invention is provided.

[0026] The meanings of the labels in the figures are as follows: 100 piezoelectric driven image shift compensation mirror device; 110 connecting base plate; 120 bearing housing; 130 reflector; 131 central pivot; 132 Annular Groove; 140 actuator assembly; 141 piezoelectric ceramic stack; 142 strain gauges; 143 Flexible Rotor; 144 return spring; 145 positioning pin; 146 Cover. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0028] This invention proposes a piezoelectric-driven image shift compensation mirror device and its control method, which is particularly suitable for optical systems such as space laser communication and adaptive systems.

[0029] To address the technical problems of existing image shift compensation mirrors that rely on external high-precision displacement sensors, resulting in bulky devices, high manufacturing costs, and limited adaptability to extreme environments (such as space radiation and wide temperature ranges), this invention proposes a piezoelectric-driven image shift compensation mirror device and its control method. It adopts an innovative strain direct feedback closed-loop control strategy, which indirectly and with high precision obtains the actual angular displacement of the mirror by directly measuring the micro-strain changes of the driving element (piezoelectric ceramic stack). Under the premise of eliminating the independent displacement sensor, it ensures the control accuracy and stability of the system and adapts to the application requirements of high-resolution optical imaging systems.

[0030] Figure 1 An overall structural diagram of a piezoelectric-driven image shift compensation mirror device according to an embodiment of the present invention is disclosed, as follows: Figure 1 As shown, the piezoelectric-driven image shift compensation mirror device 100 proposed in this invention includes a connecting base plate 110, a bearing seat 120, a reflector 130, and an actuator assembly 140. The connecting base plate 110 is used to support the overall structure of the device; The bearing seat 120 is fixedly mounted on the connecting base plate 110 and is used to realize the rotatable assembly support of the reflector 130. The reflector 130 is rotatably mounted on the bearing seat 120 and is used to receive external optical beams and reflect them in a preset direction to achieve beam pointing adjustment. The actuator assembly 140 is mounted on the bearing housing 120 and connected to the reflector 130, and is used to drive the reflector 130 to deflect around a preset axis, thereby realizing image shift compensation. The actuator assembly 140 adopts a drive structure based on direct strain feedback. By detecting the strain change of its own core drive component, it indirectly obtains the actual deflection displacement of the reflector and forms a closed-loop control based on the displacement feedback to ensure compensation accuracy.

[0031] The piezoelectric-driven image shift compensation mirror device proposed in this invention adopts a strain direct feedback drive structure. The actuator assembly detects the strain changes of its own core drive component to indirectly obtain the actual deflection displacement of the reflector and form a closed-loop control. This drives the reflector to deflect around a preset axis, achieving precise adjustment of the optical beam direction and high-precision image shift compensation closed-loop control without external high-precision displacement sensors. This eliminates the need for traditional external displacement sensors, achieving the technical effects of ensuring image shift compensation accuracy, simplifying the device structure, and improving adaptability and reliability in extreme environments. It is suitable for the application requirements of high-resolution optical imaging systems.

[0032] Figure 2 A front view of a piezoelectrically driven image shift compensation mirror device according to an embodiment of the present invention is disclosed, such as... Figure 2 As shown, the connecting base plate 110 and the bearing seats 120 on both sides work together to form a modular U-shaped frame structure. This structure has the advantages of compact structure, high rigidity and convenient assembly, which can effectively reduce the overall weight of the device and adapt to lightweight requirements such as spaceborne applications.

[0033] The connecting base plate 110 serves as the installation foundation and load-bearing core of the entire device. The bearing seats 120 are fixed at both ends by bolts and other fasteners to ensure the reliability of the assembly.

[0034] In some embodiments, to improve the dimensional stability of the device over a wide temperature range, the connecting base plate 110 is preferably made of a material with a low coefficient of thermal expansion.

[0035] Preferably, the low coefficient of thermal expansion material has a coefficient of thermal expansion of less than 1.5 × 10⁻⁶ in the temperature range of -40°C to +60°C. -6 / ℃, for example, Invar alloy. Besides Invar, other metal alloys or composite materials with similarly low coefficients of thermal expansion within the stated temperature range can also be used, such as Kovar alloys, zero-expansion microcrystalline glass, etc. Using such alloy materials can effectively suppress overall structural thermal deformation caused by changes in ambient temperature, providing a stable mechanical bearing foundation for the high-precision deflection of the mirror and preventing temperature deformation from affecting image shift compensation accuracy.

[0036] Figure 3 A schematic diagram of the overall structure of a reflector according to an embodiment of the present invention is shown, as follows: Figure 3 As shown, the reflector 130, used to receive and reflect optical beams, is rotatably mounted on the bearing housing 120 via a central pivot 131.

[0037] like Figure 2 and Figure 3 As shown, the actuator assembly 140 is mounted on the bearing seat 120 and connected to the reflector 130. It is used to drive the central rotating shaft 131 to rotate, thereby causing the reflector 130 to perform a precise deflection movement around its central rotating shaft 131 (i.e., a preset axis), thereby realizing beam pointing adjustment and image shift compensation.

[0038] Preferably, to improve the reliability of the connection between the reflector 130 and the central pivot 131, the reflector 130 is fixed to the central pivot 131 with adhesive.

[0039] Figure 4 A schematic diagram of a partial adhesive-filled structure of a reflector according to an embodiment of the present invention is shown, as follows: Figure 4As shown, a central rotating shaft 131 passes through the reflector 130, and multiple annular grooves 132 are spaced axially on its circumferential surface. These annular grooves 132 are used to fill adhesive to achieve bonding with the reflector 130. The adhesive may include, but is not limited to, optical adhesives with low shrinkage and high bonding strength, such as flexible epoxy, acrylic, or silicone.

[0040] The annular groove filling structure can effectively disperse stress concentration on the bonding surface and release assembly stress to the maximum extent, avoiding distortion of the mirror shape under temperature changes or vibration conditions, ensuring optical reflection accuracy, and improving the fatigue resistance of the connection structure.

[0041] The actuator assembly 140 serves as the core drive and displacement feedback unit of the device. Its core innovation lies in the adoption of a strain direct feedback drive structure, which can achieve closed-loop control without the need for an external displacement sensor.

[0042] In this embodiment, the actuator assembly 140 uses a symmetrically arranged dual piezoelectric ceramic stack as the core driving component. The actual angular displacement (deflection) of the reflector 130 is indirectly obtained by detecting the strain change of the driving component (piezoelectric ceramic stack), thus constructing an efficient and compact closed-loop control circuit.

[0043] Figure 5 A schematic diagram of the internal structure of an actuator assembly according to an embodiment of the present invention is disclosed, such as... Figure 5 As shown, the actuator assembly 140 includes a piezoelectric ceramic stack 141, a strain gauge 142, a flexible rotor 143, a return spring 144, and a positioning pin 145. These components work together to achieve driving, motion conversion, reset, and feedback functions. All these components are housed and fixed inside the housing of the actuator assembly 140 and encapsulated by a cover 146 to form a compact and protected internal drive unit.

[0044] The piezoelectric ceramic stack 141, as the core linear drive component, is used to receive the drive voltage and output a high-precision, high-response linear drive force to provide a power source for the deflection of the reflector 130.

[0045] In this embodiment, there are two piezoelectric ceramic stacks 141, which are arranged opposite each other with the central rotation axis 131 as the axis of symmetry to provide a balanced driving force.

[0046] In some embodiments, each piezoelectric ceramic stack 141 employs a multilayer laminated integrated structure, which is composed of hundreds of extremely thin multilayer piezoelectric ceramic sheets alternately stacked with internal electrodes. This allows the stack to achieve a large overall thrust and high-precision linear displacement output with nanometer-level resolution by accumulating the small displacements contributed by each layer at a relatively low driving voltage. For example, a single piezoelectric ceramic stack has a size of 5×5×20mm and can stably output a thrust greater than 1000N at a driving voltage of 0-100V, meeting the power requirements for mirror deflection drive.

[0047] The strain gauge 142 is disposed on the surface of the piezoelectric ceramic stack 141 and is used to detect the strain change of the piezoelectric ceramic stack 141 in real time during the expansion and contraction process, and convert this strain signal into an electrical signal as a feedback signal for closed-loop control.

[0048] Optionally, the strain gauge 142 is a semiconductor strain gauge. Preferably, its strain sensitivity coefficient is not less than 2.0, which can accurately capture the micro-strain changes of the piezoelectric ceramic stack and provide a high-precision signal for the indirect detection of the deflection motion of the reflector.

[0049] Specifically, by directly attaching this type of high-precision semiconductor strain gauge to the surface of piezoelectric stacked ceramics, the expansion and contraction strain of the piezoelectric ceramics can be obtained in real time and accurately, thereby indirectly inverting the deflection motion of the reflector.

[0050] The flexible rotor 143, as a key component for motion conversion and transmission, is connected to the output end of the piezoelectric ceramic stack 141 and the central rotating shaft 131 of the reflector 130, respectively. Its core function is to efficiently and with low loss convert the linear extension and retraction motion of the piezoelectric ceramic stack 141 into the deflection motion required by the reflector 130, while realizing motion decoupling and suppressing unnecessary coupling vibration.

[0051] In some embodiments, the flexible rotor 143 employs a flexible hinge structure such as a cross hinge. This structure is typically manufactured from a single-piece metal substrate (such as titanium alloy), and its main body has a "straight" or "cross" shape or similar structure. It has two symmetrically arranged lever arms, each of which is connected to the output end of a piezoelectric ceramic stack 141 and a return spring 144. The middle part of the flexible rotor 143 is fixed to the central axis 131 of the reflector via a positioning pin 145, thereby mechanically forming a lever system with this connection point as the rotation fulcrum. This allows the lever arms to deflect around the central axis 131 under the drive of the piezoelectric ceramic stack 141, converting the linear motion of the piezoelectric ceramic stack 141 into the rotational motion of the reflector 130.

[0052] When the piezoelectric ceramic stack 141 generates linear displacement and pushes one of its lever arms, the force is transmitted through the flexible rotor 143 and, with the help of the lever principle, the linear thrust is amplified and converted into a precise torque that drives the central rotating shaft 131 to rotate, thereby causing the reflector 130 to deflect.

[0053] Preferably, the material can be a metallic material such as titanium alloy with high yield strength and high fatigue life to ensure long-term reliable operation under repeated bending deformation conditions.

[0054] The flexible rotor 143 optimizes geometric parameters such as lever ratio, lever arm length, and structural thickness to achieve the optimal conversion between the linear motion of the piezoelectric ceramic stack 141 and the deflection motion of the reflector 130, thus achieving an optimal balance between rotational stiffness and the system's natural frequency. For example, during the design phase, parametric modeling and iterative optimization can be performed using finite element analysis (FEA) software to obtain sufficiently high structural stiffness and natural frequency while ensuring the maximum deflection angle requirement of the reflector, thereby improving the dynamic response performance of the device.

[0055] In this embodiment, the core of the precision kinematic design of the flexible rotor 143 lies in optimizing the motion transmission path: from the linear output end of the piezoelectric ceramic stack to the support point of the reflector, by accurately calculating and optimizing geometric parameters such as lever ratio, lever arm length, and structural thickness, the optimal balance between the maximum deflection angle and the driving force is achieved. The specific design steps are as follows: 1) Material selection: High yield strength and high fatigue life titanium alloy material is selected to ensure that the flexible rotor does not fail under repeated bending and deformation conditions, and to ensure the long-term reliability of the device. 2) Simulation modeling: Parametric modeling and simulation analysis are performed using finite element analysis (FEA) software (such as ANSYS and Abaqus) to accurately evaluate the rotational stiffness, maximum stress, and strain distribution under different lever ratios, lever arm lengths, and structural thicknesses. 3) Iterative optimization: Based on meeting the maximum deflection angle requirement of the reflector, calculate the minimum structural flexibility (maximum flexibility) required, and at the same time, determine the minimum support stiffness with the goal of ensuring the natural frequency of the system; by adjusting the geometric parameters of the flexible hinge, perform multiple iterations in the simulation environment, and finally obtain a set of optimal parameter combinations that can ensure the maximum deflection angle of the reflector and give the device a sufficiently high stiffness within the allowable stress range of the material.

[0056] The reset spring 144 is connected at both ends to the flexible rotor 143 and the component housing, respectively. Its function is to provide a reverse restoring force for the flexible rotor 143, which, together with the thrust of the piezoelectric ceramic stack 141, forms a "push-reset" driving mechanism to ensure that the reflector can be stably reset after deflection, ensuring the symmetry and reliability of the driving process, and at the same time providing a stable initial attitude positioning for the reflector.

[0057] In this embodiment, there are two reset springs 144, which correspond one-to-one with the two piezoelectric ceramic stacks 141, and are respectively connected to the two symmetrical lever arms of the flexible rotor 143.

[0058] The positioning pin 145, preferably one, is installed at the center hole of the flexible rotor 143 and the central rotating shaft 131 of the reflector. It is used to achieve precise positioning and fixed connection between the flexible rotor and the reflector, ensure the synchronicity and stability of motion transmission, avoid relative sliding between the flexible rotor and the central rotating shaft, and ensure the accurate transmission of drive displacement.

[0059] Compared to existing technologies that use high-precision displacement sensors, this invention eliminates the need for external displacement sensors and adopts an innovative strain direct feedback closed-loop strategy. By measuring the strain changes on the surface of the piezoelectric ceramic stack, the actual deflection displacement of the reflector is indirectly obtained. This significantly simplifies the structure, reduces the size of the device, and lowers the cost, while effectively avoiding the sensitivity of the displacement sensor to the environment and improving the environmental adaptability of the device.

[0060] To achieve high-precision image shift compensation, the piezoelectric-driven image shift compensation mirror device of the present invention is electrically connected to a control system.

[0061] In this embodiment, the control system is built on a processor device and is connected to the device via cables to realize power supply and control drive functions.

[0062] More specifically, the control system establishes an electrical connection with the actuator assembly 140 and adopts an innovative strain direct feedback closed-loop strategy. By receiving the strain feedback signal output by the strain gauge 142 in real time, it measures the strain change on the surface of the piezoelectric ceramic stack 141, indirectly and accurately obtaining the actual deflection displacement of the reflector. Based on the built-in control algorithm (such as the digital PID algorithm), the feedback signal is processed, and according to the preset image shift compensation command, the corresponding driving voltage is output to the piezoelectric ceramic stack 141, thereby realizing the closed-loop precise control of the deflection angle of the reflector 130, thus forming the core control loop and ensuring that the image shift compensation accuracy reaches the sub-pixel level.

[0063] Figure 6 A schematic diagram illustrating the mirror deflection principle according to an embodiment of the present invention is shown, as follows: Figure 6 As shown, the two piezoelectric ceramic stacks 141 in the actuator assembly 140 operate in a parallel cooperative mode.

[0064] When it is necessary to drive the reflector 130 to deflect in a certain direction, the control system applies a driving voltage of the same amplitude to the two piezoelectric ceramic stacks 141, causing them to extend synchronously and output thrust in the same direction, such as... Figure 6The arrow direction; at the same time, the reset spring 144 provides a reverse restoring force. This "push-reset" synergy, through the motion conversion of the flexible rotor 143, is ultimately converted into a torque that drives the reflector 130 to rotate around the central axis 131, thereby achieving precise deflection of the reflector 130.

[0065] Figure 7 A schematic diagram of a closed-loop feedback circuit according to an embodiment of the present invention is disclosed, such as... Figure 7 As shown, the piezoelectric-driven image shift compensation mirror device proposed in this invention also includes a control system: The control system is electrically connected to the actuator assembly 140 and is used to receive feedback signals from the strain gauge 142. Based on the difference between the feedback signals from the strain gauge 142 and the target deflection command, the control system adjusts the driving voltage applied to the piezoelectric ceramic stack to achieve closed-loop control.

[0066] The target deflection command refers to the deflection angle control command generated by the control system to drive the reflector to achieve precise image shift compensation. Its value corresponds to the desired reflector deflection angle or compensation displacement. The generation method of this command is not particularly limited: it can be issued in real time by an external host computer (such as the main control unit of the imaging system) based on the image shift detection results of the image acquisition module; it can also be generated autonomously by the control system's built-in algorithm combined with historical compensation data; or it can be preset as a fixed command during the system calibration or initialization phase to ensure the accuracy of the reflector's initial attitude.

[0067] In some embodiments, the control system mainly includes a signal conditioning circuit, a digital controller, and an actuator drive circuit. The signal conditioning circuit is connected to the strain gauge 142 and is used to receive and process the feedback signal from the strain gauge 142. The digital controller is connected to the signal conditioning circuit and is used to receive the processed feedback signal, compare it with the target deflection command to generate an error signal, and output a digital control quantity. The actuator drive circuit is connected to the digital controller and the piezoelectric ceramic stack 141, and is used to convert the digital control quantity into a drive voltage adapted to the piezoelectric ceramic stack 141, and apply it to the piezoelectric ceramic stack 141 to drive the piezoelectric ceramic stack 141.

[0068] Specifically, signal conditioning circuits typically include precision resistors and instrumentation amplifiers.

[0069] In this embodiment, the precision resistors are fixed resistors R1 and R2, which, together with the strain gauges attached to the surfaces of the two piezoelectric ceramic stacks 141, form a Wheatstone bridge. One end of the fixed resistor R1 is connected to one side of one piezoelectric ceramic stack 141, and the other end is connected to the other side of the other piezoelectric ceramic stack 141; the connection of resistor R2 is similar, forming symmetrical bridge arms. The power supply terminals of the Wheatstone bridge are connected to power supply VCC and ground GND, respectively. The differential signal output terminals Vp and Vn are taken from the connection nodes between the resistors and the piezoelectric ceramic stacks, and are used to output differential voltage signals for subsequent processing.

[0070] In this embodiment, the Wheatstone bridge converts the minute resistance change of the strain gauge 142 caused by strain into a differential voltage signal (Vp-Vn).

[0071] Subsequently, the Vp and Vn signals are fed into an instrumentation amplifier. The instrumentation amplifier then amplifies the differential signal with low noise and high common-mode rejection ratio (CMRR) for subsequent acquisition.

[0072] This Wheatstone bridge has excellent common-mode rejection capability, which can effectively suppress the effects of common-mode interference such as temperature drift.

[0073] In this embodiment, the digital controller serves as the control core and includes an analog-to-digital converter (ADC) and a digital processor (such as a DSP, FPGA, or high-performance MCU).

[0074] The ADC converts the amplified analog voltage signal into a digital quantity and transmits it to the digital processor.

[0075] The digital processor runs a control algorithm (such as a digital PID algorithm), compares the feedback signal representing the actual deflection displacement with the system's preset target deflection command, generates an error signal e(t), and calculates the digital control quantity u(t) based on this error signal.

[0076] Actuator drive circuits are used to convert digital control signals into high-voltage drive signals, and typically include digital-to-analog converters (DACs) and high-voltage drive modules.

[0077] The DAC converts the digital control quantity u(t) output by the digital controller into an analog voltage signal.

[0078] A high-voltage drive module is used to amplify the analog voltage signal to the high-voltage range (e.g., 0-150V) required to drive the piezoelectric ceramic stack.

[0079] In practical implementation, the high-voltage drive module can use a high-voltage operational amplifier or a dedicated piezoelectric drive power supply, both of which are optional technical solutions for achieving voltage amplification and current drive.

[0080] The piezoelectric-driven image shift compensation mirror device proposed in this invention has the following corresponding closed-loop control workflow for image shift compensation: When image displacement compensation is required, the control system applies voltage to the piezoelectric ceramic stack via the actuator drive circuit according to the target deflection command. The piezoelectric ceramic stack generates precise linear displacement, driving the flexible rotor.

[0081] The flexible rotor converts linear motion into torque, driving the reflector 130 to deflect around the central axis 131, thereby adjusting the optical path.

[0082] During this process, strain gauges 142, attached to the piezoelectric ceramic stack, monitor the strain state in real time. This strain state has a defined mapping relationship with the mirror rotation angle. The strain state signal is converted into a voltage feedback signal via a Wheatstone bridge and an instrumentation amplifier, and sent back to the digital controller. The digital controller compares the feedback signal with the target deflection command. If an error exists, it adjusts the output drive voltage in real time, forming a high-speed, high-precision closed-loop control loop to ensure that the mirror accurately tracks the command and achieves stable image shift compensation.

[0083] In the above process, the differential voltage signal (Vp-Vn) generated by the Wheatstone bridge is amplified by the instrumentation amplifier and compared with the target deflection command generated by the digital controller. The resulting error signal is adjusted in real time by the digital PID control algorithm to make the actual deflection displacement of the reflector 130 consistent with the target deflection command, thereby ensuring the image shift compensation accuracy.

[0084] The piezoelectric-driven image shift compensation mirror device proposed in this invention optimizes the overall structural design by using novel materials with low expansion coefficients and mirror bonding processes. In terms of system design, it replaces the displacement sensor solution with a closed-loop control system that provides direct strain feedback, effectively reducing the failure risk of electronic components and significantly improving the reliability and long-term stability of the system.

[0085] Based on the above-mentioned piezoelectric-driven image shift compensation mirror device, the present invention also proposes a piezoelectric-driven image shift compensation control method.

[0086] Figure 8 A step diagram of a piezoelectric-driven image shift compensation control method according to an embodiment of the present invention is disclosed, as follows: Figure 8 As shown, the piezoelectric-driven image shift compensation control method proposed in this invention includes the following steps: S1: Obtain the target deflection command for the reflector.

[0087] The target deflection command can be preset by the control system, corresponding to the amount of image shift that needs to be compensated.

[0088] S2: Apply a driving voltage to the piezoelectric ceramic stack in the actuator assembly to drive the mirror to deflect.

[0089] This step can be achieved through the actuator drive circuit of the aforementioned control system, which converts the control quantity into a high-voltage drive signal to drive the piezoelectric ceramic stack to produce precise linear displacement.

[0090] S3: The real-time strain of the piezoelectric ceramic stack is detected by strain gauges, and the actual deflection displacement feedback signal of the reflector is obtained based on the real-time strain.

[0091] The strain gauge's detection signal is converted into a readable voltage feedback signal via a Wheatstone bridge and signal conditioning circuit. This feedback signal has a definite mapping relationship with the actual deflection displacement of the reflector.

[0092] S4: Compare the actual deflection displacement feedback signal with the target deflection command to generate an error signal.

[0093] This step can be completed in the digital controller, by comparing the target value with the actual feedback value, calculating the deflection error in real time, and generating an error signal.

[0094] S5: Adjust the driving voltage in real time according to the error signal to achieve closed-loop control of the reflector deflection.

[0095] Based on the error signal, the control system (such as through a digital PID algorithm) dynamically adjusts the driving voltage output to the piezoelectric ceramic stack to form a high-bandwidth, high-precision closed-loop regulation, ensuring accurate tracking of the reflector deflection angle.

[0096] The piezoelectric-driven image shift compensation control method proposed in this invention can achieve sub-pixel level compensation accuracy through a strain direct feedback closed-loop mechanism, without relying on an external high-precision displacement sensor, which greatly improves the reliability of operation in extreme environments. At the same time, the integrated design of drive and feedback functions simplifies the system structure, adapts to the lightweight requirements of space-constrained scenarios, and can effectively reduce the hysteresis and error caused by indirect detection, ensuring long-term working stability.

[0097] The control system structure, actuator assembly working principle, and specific connection method of strain gauge and Wheatstone bridge, which are not described in detail in this method, can be directly referred to the corresponding technical details in the aforementioned piezoelectric driven image shift compensation mirror device embodiment, and will not be repeated here.

[0098] Although the methods described above are illustrated and depicted as a series of actions for the sake of simplicity, it should be understood and appreciated that these methods are not limited by the order of the actions, as some actions may occur in a different order and / or concurrently with other actions from the illustrations and descriptions herein or not illustrated and described herein but which may be understood by those skilled in the art, according to one or more embodiments.

[0099] In summary, the piezoelectric-driven image shift compensation mirror device and its control method provided by this invention, through the combination of an innovative flexible transmission mechanism and strain direct feedback closed-loop technology, achieves sub-pixel-level image shift compensation accuracy and kilohertz-level high dynamic response speed without the need for an external displacement sensor, and exhibits excellent environmental stability and working condition adaptability. It is especially suitable for fields with stringent requirements for size, accuracy and reliability, such as space optics and high-end observation systems.

[0100] This invention provides a piezoelectric-driven image shift compensation mirror device and control method, which specifically has the following technical effects: 1) Through the coordinated design of a precision flexible rotor, piezoelectric ceramic stacking and a high-frequency closed-loop control system, sub-pixel level image shift compensation accuracy is achieved, which can meet the stringent requirements of high-resolution imaging systems. 2) Relying on the microsecond-level response characteristics of the piezoelectric ceramic actuator, combined with a high-voltage high-speed drive power supply, the actuator can track control commands in real time. The system closed-loop response frequency exceeds 2kHz, which is suitable for high-speed dynamic image shift compensation scenarios. 3) The direct strain feedback technology, which involves directly mounting high-precision semiconductor strain gauges on the surface of a piezoelectric ceramic stack, replaces the traditional external displacement sensor. This not only simplifies the system structure but also significantly reduces the sensitivity to complex environments. 4) By using materials with low thermal expansion coefficients (such as Invar) and combining them with the annular groove potting installation process for the reflector, the thermal performance of the structure is effectively stabilized, and thermal deformation is suppressed. Within a wide temperature range of -40℃ to +80℃, image drift can be controlled within 0.1 pixels. 5) The closed-loop control method based on direct strain feedback eliminates the need for independent displacement sensors, significantly reducing the size of the device. It also avoids the risk of damage to displacement sensors, resulting in a more compact and reliable overall structure. It is especially suitable for applications with extremely high requirements for weight and reliability, such as space environments.

[0101] As indicated in this invention and the claims, unless the context clearly indicates otherwise, the words "a," "an," "an," and / or "the" do not specifically refer to the singular and may also include the plural. Generally speaking, the terms "comprising" and "including" only indicate the inclusion of explicitly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements.

[0102] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more, unless explicitly defined otherwise.

[0103] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0104] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0105] The above embodiments are provided for those skilled in the art to implement or use the present invention. Those skilled in the art can make various modifications or changes to the above embodiments without departing from the inventive concept of the present invention. Therefore, the protection scope of the present invention is not limited to the above embodiments, but should be the maximum scope that conforms to the innovative features mentioned in the claims.

Claims

1. A piezoelectrically driven image shift compensation mirror device, characterized in that, The connecting base plate, bearing seat, mirror and actuator assembly are included: The connecting base plate is used to support the overall structure of the device; The bearing seat is fixedly arranged on the connecting base plate; The mirror is rotatably mounted on the bearing seat and used to receive and reflect optical beams; The actuator assembly is mounted on the bearing seat and connected with the mirror, and is used to drive the mirror to perform deflection movement around a preset axis to realize image shift compensation; The actuator assembly adopts a driving structure based on strain direct feedback, indirectly obtains the actual deflection displacement of the mirror by detecting the strain change of the driving component, and forms closed-loop control based on displacement feedback.

2. The piezoelectrically driven image shift compensating mirror device according to claim 1, characterized in that The actuator assembly includes a piezoelectric ceramic stack, a strain gauge, a flexible rotor, a reset spring and a positioning pin: The piezoelectric ceramic stack is used as a driving component to receive a driving voltage and output a linear driving force; The strain gauge is arranged on the piezoelectric ceramic stack to detect the strain change of the piezoelectric ceramic stack in the stretching and contracting process in real time and generate a feedback signal for closed-loop control; The flexible rotor is connected between the piezoelectric ceramic stack and the mirror, and is used to convert the linear motion of the piezoelectric ceramic stack into the deflection motion of the mirror; The reset spring is connected with the flexible rotor and is used to provide a reverse restoring force to the flexible rotor; The positioning pin is arranged between the flexible rotor and the mirror to realize the positioning connection between the flexible rotor and the mirror.

3. The piezoelectrically driven image shift compensating mirror device according to claim 1, characterized in that The mirror is connected with the actuator assembly through a central rotating shaft; The actuator assembly drives the mirror to realize deflection around the central rotating shaft by driving the central rotating shaft to rotate.

4. The piezoelectrically driven image shift compensating mirror device according to claim 3, characterized in that The circumferential surface of the central rotating shaft is provided with a plurality of annular grooves; The annular grooves are used to accommodate adhesive; The mirror is fixed to the central rotating shaft by adhesive.

5. The piezoelectrically driven image shift compensating mirror device according to claim 1, wherein The connecting base plate is made of a material with low thermal expansion coefficient; The connecting base plate and the bearing seats on both sides jointly form a U-shaped frame structure.

6. The piezoelectrically driven image shift compensating mirror device according to claim 2, wherein The piezoelectric ceramic stack adopts a multi-layer integrated laminated structure formed by alternately laminating a plurality of piezoelectric ceramic sheets and internal electrodes.

7. The piezoelectrically driven image shift compensating mirror device according to claim 2, characterized in that The strain gauge is a semiconductor strain gauge, and the corresponding strain sensitivity coefficient is not less than 2.

0.

8. The piezoelectrically driven image shift compensating mirror device according to claim 2, characterized in that The flexible rotor adopts a flexible structure based on a cross hinge and has at least two symmetrically arranged force arms: Each force arm is connected with a piezoelectric ceramic stack and a reset spring, respectively; The central part of the flexible rotor is connected with the central rotating shaft of the mirror through the positioning pin, so that the force arms produce deflection around the central rotating shaft under the driving of the piezoelectric ceramic stack, and convert the linear motion of the piezoelectric ceramic stack into the rotational motion of the mirror.

9. The piezoelectrically driven image shift compensating mirror device according to claim 8, characterized in that The flexible rotor optimizes the geometric parameters of the lever ratio, the length of the force arm and the thickness of the structure to convert the linear motion of the piezoelectric ceramic stack into the deflection motion of the mirror, and balance the rotational stiffness and the system inherent frequency.

10. The piezoelectrically driven image shift compensating mirror device according to claim 2, characterized in that A control system is further included: The control system is electrically connected with the actuator assembly, used for receiving the feedback signal of the strain gauge, and adjusting the driving voltage applied to the piezoelectric ceramic stack based on the difference between the feedback signal and the target deflection instruction, to realize closed-loop control.

11. The piezoelectrically driven image shift compensating mirror device according to claim 10, characterized in that The control system mainly includes a signal conditioning circuit, a digital controller and an actuator driving circuit: The signal conditioning circuit is connected with the strain gauge, used for receiving and processing the feedback signal of the strain gauge; The digital controller is connected with the signal conditioning circuit, used for receiving the processed feedback signal, comparing with the target deflection instruction to generate an error signal, and outputting a digital control quantity; The actuator driving circuit is connected with the digital controller and the piezoelectric ceramic stack, used for converting the digital control quantity into a driving voltage suitable for the piezoelectric ceramic stack, and applying it to the piezoelectric ceramic stack to realize the driving of the piezoelectric ceramic stack.

12. A piezoelectrically driven image shift compensation control method implemented using the piezoelectrically driven image shift compensation mirror device according to any one of claims 1 to 11, characterized by, The method comprises the following steps: Obtaining the target deflection instruction of the reflector; Applying a driving voltage to the piezoelectric ceramic stack in the actuator assembly to drive the deflection of the reflector; Detecting the real-time strain of the piezoelectric ceramic stack through the strain gauge, and obtaining the actual deflection displacement feedback signal of the reflector according to the real-time strain; Comparing the feedback signal of the actual deflection displacement with the target deflection instruction to generate an error signal; And Adjusting the driving voltage in real time according to the error signal to realize closed-loop control of the deflection of the reflector.

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