A control method of a bistable light-driven oscillator and oscillator

Abstract

This invention discloses a control method and oscillator for a bistable optically driven oscillator, relating to the fields of smart materials and soft robotics. The control method for a bistable optically driven oscillator includes: establishing a light-thermal-mechanical-motion coupling model of an LCE optical fiber; determining, through the coupling model, the mapping relationship between the light intensity acting on the LCE optical fiber, the material parameters of the LCE optical fiber or the geometric parameters of the oscillator, and the oscillation frequency and critical contraction strain of the oscillator; and controlling the oscillation state of the oscillator within its self-oscillation period by adjusting the light intensity acting on the LCE optical fiber, or adjusting the spring stiffness ratio, or adjusting the initial delay distance between the slider and the light-blocking rod. Theoretical modeling reveals the regulation law of the light intensity of the LCE optical fiber, the material parameters of the LCE optical fiber, or the geometric parameters of the oscillator on the critical contraction strain and oscillation frequency, enabling precise control of the oscillator's motion state. The method is simple in structure, flexible in control, and has high assembly tolerance.

Description

Technical Field

[0001] This invention relates to the field of smart materials and soft robotics, and more specifically, to a control method and an oscillator for a bistable optically driven oscillator. Background Technology

[0002] Liquid crystal elastomers (LCEs) are a class of smart materials that combine the anisotropy of liquid crystals and the entropic elasticity of polymer networks. They can undergo reversible, large-amplitude deformation under external stimuli such as light, heat, electricity, and magnetism, with driven strains ranging from 5% to 500%. They are considered core driving materials in fields such as soft robotics, artificial muscles, and smart devices. In recent years, LCE-based self-oscillating systems, through coupling the material's own contraction-relaxation cycle with the negative feedback mechanism of the mechanical structure, can directly convert environmental light or heat energy into continuous mechanical work, showing broad application prospects in energy harvesting, micro-generators, and autonomous moving robots.

[0003] However, existing LCE self-oscillating systems mostly rely on the rapid response characteristics of materials to achieve periodic motion, requiring high intrinsic response speeds for LCEs; low-speed response materials struggle to form stable oscillations. Furthermore, most research remains focused on simple configurations such as cantilever beam oscillations and self-rotating rods, lacking complete system designs coupled with bistable mechanisms. Existing bistable structures possess state-locking and energy regulation mechanisms, and their switching delay effect can compensate for the material's need for rapid response to stimuli. However, LCEs exhibit slow photothermal responses, making them incompatible with these mechanisms. How to organically integrate the photothermal drive, self-oscillating behavior, and bistable mechanisms of LCEs into a single system to achieve a synergistic function of "light triggering—bistable switching—self-oscillation maintenance" remains a pressing technical problem to be solved. Summary of the Invention

[0004] This invention provides a control method and oscillator for a bistable optically driven oscillator, which can solve the problems of existing LCE self-oscillation systems that rely on rapid material response, have complex structures, and are difficult to control.

[0005] A control method for a bistable optically driven oscillator includes: An oscillator is provided that uses LCE fiber photostriction as the driving force, the oscillator including a spring, a slider and a light-blocking rod; Establish the optical-thermal-mechanical-motion coupling model of the LCE optical fiber; The coupling model is used to determine the mapping relationship between the light intensity acting on the LCE fiber, the material parameters of the LCE fiber or the geometric parameters of the oscillator, and the oscillation frequency and critical shrinkage strain of the oscillator. The oscillation state of the oscillator during its self-oscillation period is controlled by adjusting the light intensity acting on the LCE fiber, adjusting the spring stiffness ratio, or adjusting the initial delay distance between the slider and the light-blocking rod.

[0006] The present invention provides a control method for a bistable optically driven oscillator, which, compared with the prior art, has the following beneficial effects, but is not limited to: Theoretical modeling reveals the regulation law of critical contractile strain and oscillation frequency by the light intensity of LCE fiber, the material parameters of LCE fiber, or the geometric parameters of oscillator. It can realize precise control of oscillator motion state, with simple structure, flexible control, and high assembly tolerance.

[0007] Furthermore, the specific steps for establishing the light-heat-force-motion coupling model include: A transient temperature field model of the LCE optical fiber under illumination was established; The photoinduced shrinkage strain of the LCE fiber was calculated based on the temperature field. Establish the force balance equations for the slider, the light-blocking rod, and the spring; Determine the critical displacement condition for the light-blocking rod to flip.

[0008] Furthermore, the critical displacement condition satisfies the following equation: ; in, Xc is the critical displacement; X0 is the initial distance between the slider and the light-blocking rod; l The length from the pivot point connected to the light-blocking rod to the contact point with the slider; θ0 is the limit swing angle of the light-blocking rod.

[0009] Furthermore, the photoinduced shrinkage strain of the LCE fiber It has a linear relationship with the temperature difference T(t): ; in, This is the shrinkage coefficient.

[0010] Furthermore, the temperature difference T(t) satisfies the following when there is light: ; In the absence of light, the following conditions must be met: ; Among them, T L Let τ be the steady-state maximum temperature difference, τ be the thermal diffusion time constant, e be the base of the natural logarithm, and t be the time variable.

[0011] Furthermore, the self-oscillation period of the oscillator is determined by the right-tilt process time. t1 and left tilt process time t3 decides; in, t1 decreases as the light intensity or the shrinkage coefficient of the LCE fiber increases. t3 is determined by the spring stiffness ratio and the geometric parameters of the oscillator and is independent of the light intensity.

[0012] An oscillator, suitable for the control method described above, includes a slider, wherein a spring is connected to one side wall of the slider and an LCE optical fiber is connected to the other side wall via a flexible connector; A rotatable light-blocking rod, wherein a light-blocking plate is fixedly installed on the light-blocking rod; The spring drives the slider to move, so that the light-blocking rod and the light-blocking plate cooperate to switch the illumination conditions. Based on the illumination conditions, the LCE fiber shrinks or elongates, and the oscillator forms a periodic self-oscillation. During the periodic self-oscillation, the LCE fiber exhibits two critical states. In the first critical state, the light-blocking rod tilts to the right to be vertical and the light-blocking plate flips over. At this time, there is no light illumination, and the LCE fiber shrinks to its shortest length. In the second critical state, the light-blocking rod tilts to the left to be vertical and the light-blocking plate flips over. At this time, there is illumination, and the LCE optical fiber extends to its maximum length.

[0013] The bistable optically driven oscillator provided by this invention has, but is not limited to, the following beneficial effects compared to the prior art: When a constant line light source illuminates an LCE fiber, the fiber absorbs light energy and heats up, causing the liquid crystal cells to undergo cis-trans isomerization, resulting in macroscopic contraction of the LCE fiber. This contraction force pulls a slider to the right via a flexible connector. After moving a certain distance, the slider contacts a light-blocking rod and pushes it to rotate to the right. As the LCE fiber continues to contract, the slider continues to move to the right, and the rightward tilt angle of the light-blocking rod gradually increases. When the light-blocking rod tilts to a vertical position, the LCE fiber is in its first critical state. Due to the bistable structure design, the light-blocking rod instantly flips to the right at this point, causing the light-blocking plate to block the light source.

[0014] After the light source is blocked, the LCE fiber stops heating and begins to cool and regain its length. The spring pulls the slider to the left. After moving a certain distance to the left, the slider contacts the light-blocking rod and pushes the light-blocking rod to rotate to the left. As the LCE fiber continues to elongate, the slider continues to move to the left, and the leftward tilt angle of the light-blocking rod gradually increases. When the light-blocking rod tilts to a vertical position, the LCE fiber is in the second critical state. At this moment, the light-blocking rod instantly flips to the left, the light-blocking plate leaves the light source, and the light source illuminates the LCE fiber again, thus completing one oscillation cycle. This process repeats, achieving self-sustaining oscillation under constant illumination.

[0015] In this invention, by coupling LCE optical fiber with spring and light-blocking rod, a bistable structure is introduced in which the three cooperate with each other, and a feedback mechanism of illumination conditions is realized through light-blocking plate, so as to realize periodic oscillation motion that can be maintained autonomously without fast material response under constant illumination, which significantly reduces the dependence on the intrinsic response speed of LCE.

[0016] Furthermore, a first stop bar and a second stop bar are respectively provided on both sides of the light-blocking rod, and the first stop bar and the second stop bar are used to limit the rotation angle of the light-blocking rod.

[0017] Furthermore, the flexible connector is a thin rope.

[0018] Furthermore, the LCE optical fiber is made of a photothermal responsive liquid crystal elastomer material. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a bistable optically driven oscillator according to an embodiment of the present invention; Figure 2 This is a schematic diagram of a bistable optically driven oscillator in its initial state. Figure 3 This is a schematic diagram of a bistable optically driven oscillator in its final state. Figure 4 This is a schematic diagram of an LCE optical fiber in its initial state without deformation. Figure 5 This is a schematic diagram of the LCE optical fiber during the shrinkage process; Figure 6 This is a schematic diagram of an LCE optical fiber shrinking to the first critical state. Figure 7 This is a schematic diagram of the LCE optical fiber when it begins to elongate in the first critical state. Figure 8 This is a schematic diagram of an LCE optical fiber when it has been stretched to its initial length. Figure 9 This is a schematic diagram of an LCE optical fiber stretched to the second critical state. Figure 10The simulation curve of LCE fiber strain versus time is shown. Figure 11 This is a time variation curve of the rightward tilting process under different light intensities or contraction coefficients according to the present invention; Figure 12 This is a graph showing the time variation of the leftward tilting process under different spring stiffness ratios according to the present invention. Figure 13 This is a comparison diagram of the theoretical and experimental oscillation frequencies of this invention.

[0020] Explanation of reference numerals in the attached figures: 1. Fixed base; 2. LCE optical fiber; 3. Spring; 4. Slider; 5. Light blocking rod; 6. Light blocking plate; 7. First stop rod; 8. Second stop rod; 9. Rotating shaft. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this application clearer, specific embodiments of this application are described clearly and completely below with reference to the accompanying drawings. It should be understood that the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments described in this application without creative effort will fall within the scope of protection of this application.

[0022] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the specification of this application is for the purpose of describing specific embodiments only and is not intended to limit this application; the terms "comprising," "including," "having," "containing," "comprise," etc., in the specification, claims, and accompanying drawings of this application are open-ended terms, indicating that a method comprises one or more steps, or an apparatus comprises one or more elements, but do not exclude the inclusion of other steps or elements. The terms "first," "second," etc., in the specification, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or primary / secondary relationship. 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 with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0023] In the description of this application, it should be understood that the terms "upper", "lower", "left", "right", "front", "rear", 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 application 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 application.

[0024] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0025] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0026] Existing bistable structures are mostly used in macroscopic mechanics, switches, and relays, but there is no integrated solution that is compatible with LCE photothermal drive and self-oscillation.

[0027] Specifically, existing bistable states involve instantaneous, rapid switching, while LCEs exhibit slow photothermal responses, requiring heating and cooling times. Traditional solutions rely on high-speed material responses; forced coupling would result in immediate failure, necessitating waiting for the LCE to fully contract / recover before resuming operation.

[0028] Moreover, the existing bistable state is only responsible for locking or switching the state of self-oscillation. It does not have a negative feedback mechanism of blocking and transmitting light, and cannot automatically cut off and restore the light source. It cannot make the LCE cycle between "heating and shrinking and cooling and restoring", which means that light energy cannot be converted into continuous mechanical motion in a closed loop.

[0029] The inventors discovered that in conventional technology, LEC driving, bistable switching, and self-oscillation maintenance are three independent parts, decoupled from each other, lacking a common mechanical conduction path and critical triggering condition. Without a matching trigger chain, the continuous conduction path is missing, and the optical signal cannot be converted into bistable action. Even if bistable action is forcibly combined, the repulsion between the slow photothermal response and the instantaneous switching of bistable action leads to uncontrolled oscillation rhythm. Furthermore, bistable switching cannot automatically reset, resulting in only single-action actions and preventing the formation of sustained self-oscillation.

[0030] Therefore, existing bistable structures solve the problem of state maintenance, but cannot solve the problems of photothermal response, autonomous feedback, continuous oscillation, and are incompatible with the properties and working mechanism of LCE materials.

[0031] See Figures 1-3 As shown, an embodiment of the present invention provides a bistable optical driven oscillator, including a slider 4, a spring 3 connected to one side wall of the slider 4, and an LCE optical fiber 2 connected to the other side wall through a flexible connector.

[0032] A rotatable light-blocking rod 5, with a light-blocking plate 6 fixedly installed on the light-blocking rod 5.

[0033] Spring 3 drives slider 4 to move, so that light blocking rod 5 and light blocking plate 6 cooperate to switch the illumination conditions. Based on the illumination conditions, LCE fiber 2 shrinks or elongates, and oscillator forms periodic self-oscillation. During the periodic self-oscillation process, LCE fiber 2 exhibits two critical states.

[0034] In the first critical state, the light-blocking rod 5 tilts to the right to be vertical and the light-blocking plate 6 flips over. At this time, there is no light, and the LCE fiber 2 shrinks to its shortest length.

[0035] In the second critical state, the light-blocking rod 5 tilts to the left to be vertical and the light-blocking plate 6 flips over. At this time, there is illumination, and the LCE fiber 2 extends to its maximum length.

[0036] In this embodiment, the original length of LCE fiber 2 is denoted as . The end of the LCE fiber 2 furthest from the slider 4 is fixed to an alligator clip bracket on the mounting base 1. The end of the spring 3 furthest from the slider 4 is fixed to the mounting base 1. In the initial state, both the spring 3 and the LCE fiber 2 are pre-stretched, and their tensions are balanced. The slider 4 can slide freely along a horizontal guide rail (not shown in the figure). The light-blocking rod 5 is mounted on the mounting base 1 via a pivot 9, allowing the light-blocking rod 5 to rotate around the pivot 9. The light-blocking plate 6 fixed on the light-blocking rod 5 is used to block or expose the light source, thereby achieving the switching of lighting conditions.

[0037] See Figures 4-7 As shown, when a constant line light source illuminates the LCE fiber 2, the LCE fiber 2 absorbs light energy and heats up, causing the liquid crystal cells to undergo cis-trans isomerization, resulting in macroscopic contraction of the LCE fiber 2. The contraction force pulls the slider 4 to the right through the flexible connector. After moving a certain distance, the slider 4 contacts the light-blocking rod 5 and pushes the light-blocking rod 5 to rotate to the right around the pivot 9. As the LCE fiber 2 continues to contract, the slider 4 continues to move to the right, and the rightward tilt angle of the light-blocking rod 5 gradually increases. When the light-blocking rod 5 tilts to the right to a vertical position (angle of 0°), the LCE fiber 2 is in the first critical state. Due to the bistable structure design, the light-blocking rod 5 will instantly flip to the right at this time, causing the light-blocking plate 6 to block the light source.

[0038] See Figures 8-9As shown, after the light source is blocked, the LCE fiber 2 stops heating and begins to cool and recover its length. The tension of the spring 3 pulls the slider 4 to the left. After moving a certain distance to the left, the slider 4 contacts the light-blocking rod 5 and pushes the light-blocking rod 5 to rotate to the left. As the LCE fiber 2 continues to elongate, the slider 4 continues to move to the left, and the left tilt angle of the light-blocking rod 5 gradually increases. When the light-blocking rod 5 tilts to the left to a vertical position, the LCE fiber 2 is in the second critical state. At this time, the light-blocking rod 5 flips to the left instantaneously, the light-blocking plate 6 leaves the light source, and the light source illuminates the LCE fiber 2 again, thus completing one oscillation cycle. This process repeats to achieve self-sustaining oscillation under constant illumination.

[0039] In this invention, by coupling the LCE fiber 2 with the spring 3 and the light-blocking rod 5, a bistable structure is introduced in which the three cooperate with each other, and the light-blocking plate 6 realizes the feedback mechanism of the illumination condition, realizing the periodic oscillation motion that can be maintained autonomously without fast material response under constant illumination, which significantly reduces the dependence on the intrinsic response speed of LCE.

[0040] During the self-oscillation period, the rapid, instantaneous, and irreversible attitude reversal process occurs between the left stable attitude in the second critical state and the right stable attitude in the first critical state during the bistable switching. The time delay effect brought about by the bistable switching allows the oscillator to trigger the reversal before the material shrinkage or recovery of LCE fiber 2 is completed, providing sufficient thermal shrinkage and recovery time for LCE and solving the technical bottleneck of traditional LCE oscillators that rely on the instantaneous response of materials.

[0041] Optionally, a first stop bar 7 and a second stop bar 8 are respectively provided on both sides of the light-blocking rod 5. The first stop bar 7 and the second stop bar 8 are used to limit the rotation angle of the light-blocking rod 5.

[0042] In this embodiment, the first stop lever 7 and the second stop lever 8 are located on the left and right sides of the light-blocking lever 5, which can limit the extreme rotation angle of the light-blocking lever 5. The extreme rotation angle can be adjusted according to actual needs, that is, by changing the position of the first stop lever 7 (second stop lever 8). The extreme rotation angle in this embodiment is ±15°.

[0043] The setting of the first stop lever 7 and the second stop lever 8 can keep the light blocking lever 5 stably in the left tilt steady state position and the right tilt steady state position, avoid excessive movement, ensure reliable bistable switching and stable self-sustaining oscillation operation.

[0044] Specifically, after the light-blocking rod 5 completes its flip, it rests against the first stop rod 7 and the second stop rod 8 respectively, thus stably maintaining the two extreme postures of left-tilt steady state and right-tilt steady state, ensuring clear bistable switching and fixed position without arbitrary shaking. By fixing the extreme swing angle, the travel distance and rotation amplitude of each right-tilt and left-tilt are unified, making the critical conditions for triggering the bistable flip consistent each time, ensuring the self-sustaining oscillation stability and regular periodicity of the entire oscillator. Limiting the maximum swing angle, in conjunction with the displacement of the slider 4 and the structural geometry, can precisely match the triggering timing when the light-blocking rod 5 reaches the vertical critical position, ensuring stable light feedback on / off timing and maintaining closed-loop self-oscillation. While satisfying photothermal coupling and bistable critical triggering, it also satisfies negative feedback light blocking.

[0045] Optionally, the flexible connector is a thin rope.

[0046] In this embodiment, a thin rope is used as a flexible connector, transmitting the contraction tension of the LCE fiber 2 in only one direction, thus avoiding lateral forces and motion interference. Simultaneously, the flexibility and low motion resistance of the thin rope are utilized to adapt to the reciprocating coupling motion of the slider 4 and the light-blocking rod 5, reducing power loss and ensuring a smooth and reliable self-oscillation process.

[0047] Specifically, the LCE fiber 2 can only output axial contraction tension, and the thin rope is a flexible one-dimensional component that stretches and pulls the slider 4 synchronously with the deformation of the LCE fiber 2. It will not generate radial off-center load or torsional torque on the slider 4, ensuring that the slider 4 always slides horizontally and smoothly, and avoiding motion jamming.

[0048] The flexibility of the thin rope can reduce motion interference. During the reciprocating swing of the light-blocking rod 5 and the reciprocating linear motion of the slider 4, there are slight positional deviations. The thin rope has flexible and bendable characteristics, which can adapt to the slight positional deviations. If the thin rope is replaced with a rigid connecting rod, jamming and overload problems are likely to occur. Therefore, the thin rope is more suitable for the reciprocating oscillating motion conditions in this application.

[0049] Moreover, the thin rope is lightweight, has low bending resistance, and negligible deformation, so it will not consume additional contraction driving force of LCE fiber 2, thus preserving the effective output of photo-induced contraction to the maximum extent and ensuring that the oscillator can stably trigger bistable switching.

[0050] Optionally, the LCE fiber 2 is made of a photothermal responsive liquid crystal elastomer material.

[0051] In another embodiment, the present invention provides a control method for a bistable optically driven oscillator as described above, comprising: An oscillator is provided, which is driven by photoextension of LCE fiber 2. The oscillator includes a spring 3, a slider 4 and a light-blocking rod 5.

[0052] Establish an optical-thermal-mechanical-motion coupling model for LCE fiber 2.

[0053] By using a coupling model, the mapping relationship between the light intensity acting on LCE fiber 2, the material parameters of LCE fiber 2 or the geometric parameters of the oscillator, and the oscillation frequency and critical contraction strain of the oscillator is determined.

[0054] The oscillation state of the oscillator during its self-oscillation period is controlled by adjusting the light intensity acting on the LCE fiber 2, adjusting the stiffness of the spring 3, or adjusting the initial delay distance between the slider 4 and the light-blocking rod 5.

[0055] In this embodiment, theoretical modeling reveals the regulation law of the light intensity of LCE fiber 2, the material parameters of LCE fiber 2 (including but not limited to the shrinkage coefficient, thermal diffusion time constant, photothermal conversion efficiency, and elastic coefficient of LCE fiber 2) or the geometric parameters of the oscillator (including but not limited to the initial delay distance between slider 4 and light-blocking rod 5, the length of light-blocking rod 5, and the limit rotation angle of light-blocking rod 5) on the critical shrinkage strain and oscillation frequency. This enables precise control of the oscillator's motion state, with a simple structure, flexible control, and high assembly tolerance.

[0056] The control method of the bistable light-driven oscillator of the present invention does not require an external power supply, controller or chemical fuel for the oscillator. It can work with only a constant light source and is applicable to soft robots, adaptive sensors, energy harvesting devices and micro autonomous mobile devices.

[0057] The specific steps for establishing a coupled light-thermal-mechanical-motion model include the following: A transient temperature field model of LCE fiber 2 under illumination was established.

[0058] The photoinduced shrinkage strain of LCE fiber 2 was calculated based on the temperature field.

[0059] Establish the force balance equations for slider 4, light-blocking rod 5, and spring 3.

[0060] Determine the critical displacement condition for the light-blocking rod 5 to flip.

[0061] Specifically, the photoinduced shrinkage strain of LCE optical fiber It has a linear relationship with the temperature difference T(t): ; in, This is the shrinkage coefficient.

[0062] The temperature difference T(t) satisfies the following when there is light: ; In the absence of light, the following conditions must be met: ; Among them, T L Let τ be the steady-state maximum temperature difference, e be the base of the natural logarithm (approximately 2.71828), and t be the time variable. This formula describes the exponential decay of the temperature of LCE fiber 2 over time in the absence of illumination.

[0063] The critical displacement condition satisfies the following equation: ; in, Xc is the critical displacement; X0 is the initial distance between slider 4 and light-blocking rod 5; l The length from the rotating shaft 9 connected to the light-blocking rod 5 to the point of contact with the slider 4; θ0 is the limit swing angle of the light-blocking rod 5.

[0064] It should be noted that the self-oscillation period of the oscillator is determined by the time of the right-tilt process. t1 and left tilt process time t3 makes the decision.

[0065] in, t1 decreases with increasing light intensity or the shrinkage coefficient of LCE fiber 2. t3 is determined by the stiffness of spring 3 and the geometric parameters of the oscillator and is independent of the light intensity.

[0066] This embodiment performs force analysis and motion modeling on a bistable optically driven oscillator and establishes a control method, specifically including the following steps: S1. Establish the geometric relationship between displacement and angle.

[0067] Let the angle between the light-blocking rod 5 and the vertical direction be θ, the initial left tilt angle be θ0 (take a positive value), and the distance from the rotating shaft 9 to the contact point of the slider 4 be... l The initial horizontal distance between slider 4 and light-blocking rod 5 is X0. The displacement X1 of slider 4 to the right satisfies: ; The flip condition is θ=0, from which the critical displacement is obtained: ; The positive sign corresponds to flipping to the right, and the negative sign corresponds to flipping to the left.

[0068] S2. Establish the force balance equation.

[0069] L1 is the original length of LCE fiber 2, L2 is the original length of spring 3 in its natural state, and the elastic modulus of LCE fiber 2 is K. L The spring constant of spring 3 is K. SThe initial pre-tension strains are γ1 and γ2, respectively. At initial equilibrium: ; During the motion, the net force on slider 4 is zero: ; Spring force The elastic force of LCE fiber 2 , For elastic strain. Total strain. ,in For photoinduced contractile strain, and Therefore, we can conclude that: .

[0070] S3. Establish a photothermal response model.

[0071] Photoinduced contractile strain Linearly correlated with temperature difference T(t): ; Where C0 is the shrinkage coefficient.

[0072] The temperature difference satisfies the thermal diffusion equation: ; Solving for: .

[0073] S4. Determine the critical contraction strain and oscillation conditions.

[0074] Self-oscillation requirement: Maximum contraction strain of LCE fiber 2 under illumination And the minimum recoverable strain in the dark state . and It is determined by the geometric parameters and the stiffness of spring 3.

[0075] in, The maximum contraction strain of LCE fiber 2 under illumination. The right-tilt critical contraction strain of LCE fiber 2. The minimum recovering strain of LCE fiber 2 in the dark state is given by [reference needed]. The left-tilting critical contraction strain is the LCE fiber 2.

[0076] By adjusting the initial delay distance X0 (i.e., the initial distance between slider 4 and light-blocking rod 5) and the length of light-blocking rod 5... l Limit angle θ0, spring stiffness ratio 3 It can change the critical strain value, thereby controlling the start-up and shutdown of the oscillator and the oscillation frequency.

[0077] S5, Adjust the oscillation cycle.

[0078] Time of right tilt process (LCE fiber 2 contraction drive) With light intensity (proportional to) The coefficient of contraction, C0, increases and decreases monotonically, exhibiting a non-linear relationship. The time of the leftward tilting process (spring-driven recovery)... The total oscillation period is determined by the stiffness and geometric parameters of spring 3 and is independent of the light intensity. Therefore, the total oscillation period can be precisely controlled by adjusting the light intensity or the material parameters (contraction coefficient) of LCE fiber 2.

[0079] Figure 10 The strain exhibits a cyclical pattern of change over time: the strain first rises nonlinearly to a peak, then decreases nonlinearly, completing one "loading-unloading" process, and then repeats the same deformation pattern. The curve is smooth and continuous, and the peak and trough values ​​of each cycle are highly consistent, demonstrating the repeatability of the material's deformation behavior.

[0080] Figure 11 Showing the duration of right tilt The variation of photothermal intensity Q [Q represents the heat power density (or heat intensity) generated by photothermal conversion, i.e. the energy absorbed by a unit volume (or unit mass) of liquid crystal elastomer (LCE fiber 2) and converted into heat energy per unit time] and shrinkage coefficient C0. Figure 11 (a) and Figure 11 The strain curve in (c) shows that increasing Q or C0 can significantly accelerate the heating process (i.e., shorten the heating time t) and reduce the strain. It rises from the left critical point to the right critical point more quickly. Figure 11 (b) shows the case where C0 = 0.25. It decreases monotonically as Q increases. Correspondingly, Figure 11 In (d) where Q=3.2 is fixed, As C0 increases (the unit of C0 is K), -1 The rightward tilt (i.e., the shrinkage strain generated per Kelvin) decreases rapidly. Overall, the duration of the rightward tilt decreases with increasing heating intensity or material shrinkage coefficient, and there is a clear parameter boundary; below the boundary, the system cannot enter the rightward tilt state.

[0081] Figure 12This refers to the effect of the spring stiffness ratio K on the critical strain of LCE optical fiber: as the spring stiffness ratio K increases, both the left critical strain (the left critical strain is represented by the red line corresponding to the dark mode at the bottom of the figure) and the right critical strain (the right critical strain is represented by the blue line corresponding to the bright mode at the top) increase linearly. When K is less than 0.12, the left critical strain is too small, and the system cannot overcome the resistance to enter the left-tilting critical state; when K is greater than 0.32, the right critical strain exceeds the maximum allowable shrinkage strain of the material, and the LCE optical fiber 2 will be damaged. Therefore, the feasible range for the spring stiffness ratio K is 0.12-0.32.

[0082] Figure 13 Experimental data and theoretical predictions regarding the self-oscillation frequency as a function of illumination power were compared. The region below 20W represents the threshold range where the system cannot initiate oscillation. The theoretical curve (solid green line) exhibits exponential saturation growth, asymptotically approaching 0.11Hz. The experimental data points (red dots) in the range of 20W to 60W closely match the theoretical curve, with the frequency monotonically increasing with power, reaching approximately 0.11Hz at 60W. The results demonstrate that the established model accurately describes the frequency response characteristics of the bistable LCE self-oscillator.

[0083] The above-disclosed embodiments are merely a few specific examples of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A control method for a bistable optically driven oscillator, characterized in that, include: An oscillator is provided that uses photoextension of an LCE fiber (2) as the driving force, the oscillator comprising a spring (3), a slider (4) and a light-blocking rod (5). Establish the optical-thermal-mechanical-motion coupling model of the LCE fiber (2); The coupling model is used to determine the mapping relationship between the light intensity acting on the LCE fiber (2), the material parameters of the LCE fiber (2) or the geometric parameters of the oscillator and the oscillation frequency and critical contraction strain of the oscillator; The oscillation state of the oscillator during its self-oscillation period is controlled by adjusting the light intensity acting on the LCE fiber (2), adjusting the stiffness of the spring (3), or adjusting the initial delay distance between the slider (4) and the light-blocking rod (5).

2. The control method as described in claim 1, characterized in that, The specific steps for establishing the optical-thermal-mechanical-motion coupling model include: Establish a transient temperature field model for the LCE fiber (2) under illumination; The photoinduced shrinkage strain of the LCE fiber (2) was calculated based on the temperature field. Establish the force balance equations for the slider (4), the light-blocking rod (5), and the spring (3); Determine the critical displacement condition for the light-blocking rod (5) to flip.

3. The control method as described in claim 2, characterized in that, The critical displacement condition satisfies the following equation: ； in, Xc is the critical displacement; X0 is the initial distance between the slider (4) and the light-blocking rod (5); l The length from the pivot (9) connected to the light-blocking rod (5) to the point of contact with the slider (4); θ0 is the limit swing angle of the light-blocking rod (5).

4. The control method as described in claim 2, characterized in that, Photoinduced shrinkage strain of LCE optical fiber It has a linear relationship with the temperature difference T(t): ； in, This is the shrinkage coefficient.

5. The control method as described in claim 4, characterized in that, The temperature difference T(t) satisfies the following when there is light: ； In the absence of light, the following conditions must be met: ； Among them, T L Let τ be the steady-state maximum temperature difference, τ be the thermal diffusion time constant, e be the base of the natural logarithm, and t be the time variable.

6. The control method as described in claim 1, characterized in that, The self-oscillation period of the oscillator is determined by the right-tilting process time. t1 and left tilt process time t3 decides; in, t1 decreases with increasing light intensity or the shrinkage coefficient of the LCE fiber (2). t3 is determined by the stiffness of the spring (3) and the geometric parameters of the oscillator and is independent of the light intensity.

7. An oscillator suitable for the control method as described in any one of claims 1-6, characterized in that, Includes a slider (4), one side wall of which is connected to a spring (3), and the other side wall is connected to an LCE optical fiber (2) via a flexible connector; A rotatable light-blocking rod (5), on which a light-blocking plate (6) is fixedly installed; The spring (3) drives the slider (4) to move, so that the light-blocking rod (5) and the light-blocking plate (6) cooperate to switch the illumination conditions. Based on the illumination conditions, the LCE fiber (2) shrinks or stretches, and the oscillator forms a periodic self-oscillation. During the periodic self-oscillation, the LCE fiber (2) exhibits two critical states. In the first critical state, the light-blocking rod (5) tilts to the right to be vertical and the light-blocking plate (6) flips over. At this time, there is no light illumination, and the LCE fiber (2) shrinks to its shortest length. In the second critical state, the light-blocking rod (5) tilts to the left to be vertical and the light-blocking plate (6) flips over. At this time, there is illumination, and the LCE optical fiber (2) extends to its longest length.

8. The oscillator as claimed in claim 7, characterized in that, The light-blocking rod (5) is provided with a first stop bar (7) and a second stop bar (8) on both sides, and the first stop bar (7) and the second stop bar (8) are used to limit the rotation angle of the light-blocking rod (5).

9. The oscillator as claimed in claim 7, characterized in that, The flexible connector is a thin rope.

10. The oscillator as claimed in claim 7, characterized in that, The LCE optical fiber (2) is made of photothermal responsive liquid crystal elastomer material.

Images