An apparatus for regulating photosensitive robot motion based on vector light field

Abstract

A device for regulating photosensitive robot movement based on vector light field, comprising a laser, a first linear polarizer, a first quarter-wave plate, a reflective spatial light modulator, a second quarter-wave plate, a beam expander, a photosensitive robot with four photosensitive resistors on top, an imaging lens, and a computer connected therewith; the spatial light modulator can realize a vector light field with an arbitrary polarization direction distribution in a plane, the vector light field is enlarged to a horizontal plane with a meter scale through the beam expander, the photosensitive robot on the horizontal plane obtains light intensity values through the four photosensitive resistors, a microprocessor built in the robot calculates local polarization direction and light intensity information, after obtaining the polarization direction, the robot takes some actions according to program commands, such as turning to the local polarization direction, thereby realizing directional movement and clustering of the photosensitive robot.

Description

Technical Field

[0001] This invention relates to the field of robot control, and in particular to a device for controlling the motion of a photosensitive robot based on a vector light field. Background Technology

[0002] A vector light field refers to an optical electromagnetic field with a specific polarization state distribution in the spatial domain. Typically, the propagation direction of a vector light field is called the z-axis, and it has different polarization states in different regions of the xy-plane. Define φ(x,y,t) as the polarization direction at the point (x,y) in the plane at time t; any single-valued function φ(x,y,t) can represent the vector light field. Existing techniques can generate arbitrary vector light fields through a combination of a spatial light modulator and a quarter-wave plate.

[0003] Reactive substances are a typical type of non-equilibrium system, composed of a large number of active individuals that gain self-propulsion by converting other forms of energy into kinetic energy. Precise regulation of reactive substances is a very real need and one of the conditions for their effective application in various fields. Whether it's regulating population distribution in ecosystems or targeted drug delivery in cancer treatment, research in this area is indispensable. In current experimental research on reactive substances, robotic systems play a crucial role.

[0004] Compared to living organisms, robotic active matter offers advantages such as controllable interactions and strong scalability, making it an excellent experimental platform for studying active matter. In traditional research, researchers have controlled robotics using methods such as light field intensity or wireless communication commands. However, light field intensity control suffers from poor spatial resolution because the external field is typically spatially uniform. While wireless communication commands allow for precise control of the speed and direction of a single robot, or simultaneous control of multiple robots, the number of robots that can be controlled is limited by the number of wireless communication channels. Furthermore, experimental platforms using wireless communication for command transmission place high demands on the robot's hardware.

[0005] Patent document CN116560061A discloses a device for controlling the movement of photoreceptor cells based on a vector light field. It uses a spatial light modulator to generate an adjustable arbitrary vector light field, with the controllability range of the vector light field at the centimeter level. However, it is only suitable for manipulating microorganisms (such as cells), and the response of microorganisms to the vector light field is relatively deterministic and difficult to change. Summary of the Invention

[0006] To address the above problems, this invention combines the technology of generating arbitrary vector light fields using spatial light modulators to propose a device for controlling the motion of a photosensitive robot based on vector light fields. The device controls the motion of a simple photosensitive robot within a meter-scale range using vector light fields, and records the control effect using an imaging lens.

[0007] The technical solution of the present invention is as follows:

[0008] A device for controlling the motion of a photosensitive robot based on vector light field, the device comprising, in sequence, a laser, a first linear polarizer, a first quarter-wave plate, a reflective spatial light modulator, a second quarter-wave plate, a beam expander, a photosensitive robot with four photoresistors mounted on top, a second linear polarizer, a third linear polarizer, a fourth linear polarizer, a fifth linear polarizer, an imaging lens, and a computer connected to a camera.

[0009] The computer can display and process images of the robot's movements in real time.

[0010] The spatial light modulator chip is rectangular, with its long side as the x-axis and its short side as the y-axis. The polarization direction of the first linear polarizer is parallel to the x-axis. The laser beam emitted from the laser passes through the first linear polarizer to form linearly polarized light with a polarization direction parallel to the x-axis.

[0011] The first quarter-wave plate has a fast axis direction that makes an angle of 45° with the x-axis, and linearly polarized light becomes circularly polarized light after passing through the first quarter-wave plate.

[0012] The spatial light modulator chip has a resolution of 1920x1200 and is capable of modulating the phase of the electromagnetic wave illuminating that point at each point. After circularly polarized light is reflected by the spatial light modulator chip, the phase of the circularly polarized light reflected at each point changes, and the change value is controlled by the input signal of the spatial light modulator.

[0013] The fast axis of the second quarter-wave plate forms an angle of 135° with the x-axis. Circularly polarized light reflected from the spatial light modulator becomes linearly polarized light after passing through the second quarter-wave plate. The polarization direction at each point is determined by the previous phase change value. The polarized light with different polarization directions at different locations in space forms a vector light field, which is then magnified by the beam expander to form a vector light field with a size of approximately 1.8 x 1.4 m.

[0014] The photosensitive robot is positioned on the horizontal plane of the vector light field. The local polarization direction is determined by the light intensity values ​​obtained through four photoresistors, and the embedded control program regulates the movement of the photosensitive robot.

[0015] The camera connected to the imaging lens records real-time images of the robot's movement and outputs these images to a computer for storage. The computer can also process the corresponding images in real time, acquire robot motion information, and modify this information to change the input information of the spatial light modulator, thereby achieving real-time control of the robot.

[0016] The first quarter-wave plate Jones matrix is In the formula, i is the imaginary unit.

[0017] The second quarter-wave plate Jones matrix is

[0018] The Jones matrix of the reflective spatial light modulator is... In the formula, φ represents the information input of the spatial light modulator. In a spatial light modulator with a resolution of 1920x1200, each pixel can be set to a different φ value.

[0019] The Jones matrix of the vector light field is

[0020] The Jones matrix of the vector light field is equivalent to the matrix with a rotation angle of . The rotation matrix, therefore, by rotating the ingested linearly polarized light at each pixel point by a different... Angles can be used to obtain arbitrary vector light fields.

[0021] The photosensitive robot is a common wheeled robot made of simple hardware. It is equipped with four photoresistors and four linear polarizers are placed at 0°, 45°, 90° and 135° with the robot's forward direction as the reference axis. The robot is driven by an Arduino Uno board.

[0022] The principle of determining the local polarization direction by the light intensity values ​​obtained from four photoresistors is as follows: According to Malus's law, linearly polarized light with intensity I0, after passing through the analyzer, has a transmitted light intensity of I0cosθ. 2 (α), where α is the angle between the polarization direction of the incident linearly polarized light and the polarization direction of the analyzer. We assume that the linearly polarized light formed by the second quarter-wave plate, after passing through the second, third, fourth, and fifth linear polarizers, will have its intensity obtained by the corresponding photoresistor determined by the following expression.

[0023]

[0024] Where x represents the orientation of the four linear polarizers, f(x) is the light intensity value obtained by the corresponding photoresistor, A is a coefficient related to the light intensity value of the linearly polarized light transmitted through the second, third, fourth and fifth linear polarizers, and B is a positive constant that satisfies |A|=B. It is the local polarization direction (with the robot's forward direction as the reference axis, and the counterclockwise direction as the positive direction). Let the light intensity values ​​obtained by the photoresistors placed under the four linear polarizers at 0°, 45°, 90°, and 135° at any given time be I1, I2, I3, and I4, respectively. From equation (1), we can obtain...

[0025]

[0026]

[0027]

[0028]

[0029] The light intensity values ​​obtained using four photoresistors can be obtained from equation (2a, 2b, 2c, 2d). Right now

[0030]

[0031] The embedded control program of the photosensitive robot is as follows: the local polarization direction is calculated using equation (3). Then adjust the robot's angular velocity (counterclockwise is the positive direction). C represents the modulation intensity, which causes the robot to turn towards the local polarization direction, thus enabling the robot's directional movement.

[0032] Compared with the prior art, the beneficial effects of the present invention are:

[0033] By amplifying vector light fields to the meter scale, precise control of the motion of centimeter-level photosensitive robots with simple hardware can be achieved. Compared to microorganisms, the robot's response to vector light fields is more programmable, offering more controllable methods. This technology provides new possibilities for flexibly manipulating robots in a wide range of diverse scenarios. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of a device for controlling the motion of a photosensitive robot based on a vector light field, according to the present invention.

[0035] Figure 2 This is the first example of a vector light field distribution according to the present invention.

[0036] Figure 3 This is the second example of vector light field distribution in this invention.

[0037] In the diagram, 1 is a laser, 2 is a first linear polarizer, 3 is a first quarter-wave plate, 4 is a spatial light modulator, 5 is a second quarter-wave plate, 6 is a beam expander, 7 is a photosensitive robot with four photoresistors mounted on top, 8 is a second linear polarizer placed at 0° with the robot's forward direction as the reference axis, 9 is a third linear polarizer placed at 45°, 10 is a fourth linear polarizer placed at 90°, 11 is a fifth linear polarizer placed at 135°, 12 is an imaging lens, and 13 is a computer that saves and processes real-time images. Detailed Implementation

[0038] To better illustrate the content of this invention, the following description is provided in conjunction with the accompanying drawings and examples.

[0039] In this embodiment, a common wheeled robot is constructed from simple hardware. Four photoresistors are mounted on the top of the robot, each with a linear polarizer. The photoresistors are positioned at 0°, 45°, 90° and 135° respectively (with the robot's forward direction as the reference axis). The robot is driven by an Arduino Uno.

[0040] A 520 nm green laser 1 with a power of 3 W and a beam diameter of approximately 25 mm is used. After passing through a first linear polarizer 2, the light becomes linearly polarized, and the polarization direction of this linearly polarized light is parallel to the x-direction of the reflective spatial light modulator 4. Then, the linearly polarized light passes through a vector light field generation module consisting of a first quarter-wave plate, a spatial light modulator, and a second quarter-wave plate (3-4-5) to form a vector light field. This vector light field is then magnified by a beam expander lens (6) with a focal length of 12 mm and projected onto the ground to form a 1.8 x 1.4 m vector light field. A photosensitive robot (7) moves within this vector light field, and a camera connected to an imaging lens (12) with a focal length of 8 mm records the real-time control effect.

[0041] This embodiment uses two vector light fields as examples.

[0042] Example 1:

[0043] The polarization direction of the input linearly polarized light is θ(ρ,η)=0, and the input signal of the spatial light modulator is... Therefore, the distribution of polarization directions in the vector light field is as follows: The polarization direction of this vector light field has Figure 2 As shown in the directional distribution, under the influence of this vector light field, the photosensitive robot will converge at the center.

[0044] Example 2:

[0045] The polarization direction of the input linearly polarized light is θ(ρ,η)=0, and the input signal of the spatial light modulator is... Therefore, the distribution of polarization directions in the vector light field is as follows: The polarization direction of this vector light field has Figure 3 The directional distribution is shown. Under the influence of this vector light field, multiple photosensitive robots will converge on the two circular tracks at the lower left and upper right (r is used to adjust the position of the two circular tracks), and rotate within them.

Claims

1. A device for controlling the motion of a photosensitive robot based on a vector light field, characterized in that, It includes a first linear polarizer arranged sequentially along the transmission direction of the laser's output beam, a vector light field generation module consisting of a first quarter-wave plate, a reflective spatial light modulator, and a second quarter-wave plate, and a beam expander module. The output beam of the laser is converted into linearly polarized light by the first linear polarizer. The linearly polarized light is parallel to the X-axis direction of the reflective spatial light modulator. The linearly polarized light is generated into a vector light field by the vector light field generation module and then expanded and amplified to a horizontal plane of the vector light field on the meter scale by the beam expansion module. The photosensitive robot moves on the horizontal plane of the vector light field. The imaging module acquires real-time motion images of the photosensitive robot and transmits them to the computer, thereby obtaining motion information of the photosensitive robot, changing the input information of the spatial light modulator, and realizing real-time control of the photosensitive robot. The top of the photosensitive robot is equipped with four photoresistors for acquiring light intensity values. Each photoresistor is equipped with a linear polarizer. With the forward direction of the photosensitive robot as the reference axis, the polarization directions of the four linear polarizers are 0°, 45°, 90° and 135° respectively. The photosensitive robot has a built-in microprocessor that calculates the local polarization direction and light intensity information based on the acquired light intensity value. The fast axis of the first quarter-wave plate makes an angle of 45° with the x-axis, and linearly polarized light is transformed into circularly polarized light after passing through the first quarter-wave plate. The fast axis of the second quarter-wave plate forms an angle of 135° with the x-axis. Circularly polarized light reflected from the spatial light modulator becomes linearly polarized light after passing through the second quarter-wave plate. The polarization direction at each point is determined by the previous phase change value. Polarized light with different polarization directions at different locations in space forms a vector light field.

2. The device for controlling the motion of a photosensitive robot based on a vector light field according to claim 1, characterized in that, The spatial light modulator (4) chip is rectangular, with the long side as the x-axis and the short side as the y-axis. The polarization direction of the first linear polarizer (2) is parallel to the x-axis. The laser beam emitted from the laser (1) passes through the first linear polarizer (2) to form linearly polarized light with a polarization direction parallel to the x-axis.

3. The device for controlling the motion of a photosensitive robot based on a vector light field according to claim 2, characterized in that, The spatial light modulator chip has a resolution of 1920x1200 and the ability to modulate the phase of the electromagnetic wave illuminating that point at each point. After circularly polarized light is reflected by the spatial light modulator chip, the phase of the circularly polarized light reflected at each point will change, and the change value is controlled by the input signal of the spatial light modulator.

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