Stray light suppression method for four-PSD robot calibration device

Abstract

A stray light suppression method for a four-PSD robot calibration device belongs to the technical field of laser measuring instruments, and aims to solve the problems in the prior art, the method comprises the following steps: S1, light incident angle calibration: arranging a PSD I and a PSD II in a light shield, uniformly coating extinction paint on the inner surface of the light shield, coaxially arranging a plane mirror and a reflector with an optical filter, and calibrating the light incident angle; the light filter is arranged on the lower surface of the reflector, the light L1 enters the plane mirror, a light spot G1 is presented on the plane mirror, the light L2 enters the reflector through refraction of the plane mirror and is reflected by the reflector to form reflected light L3, a light spot G2 is presented on the plane mirror, and part of light L4 reflected by the light L3 entering the plane mirror is absorbed by the extinction paint. The incident angle alpha of the light L1 is adjusted until the light spot G1 and the light spot G2 presented on the plane mirror coincide, and calibration is finished; s2, stray light filtering processing; s3, carrying out stray light extinction treatment; the method can be widely applied to laser measuring instruments requiring high-precision light spot position information.

Description

Technical Field

[0001] The present invention belongs to the technical field of laser measuring instruments, and particularly relates to a stray light suppression method for a four-PSD (Position Sensitive Detector) robot calibration device. Background Art

[0002] In the high-precision operation of a robot, accurate calibration is the key to ensuring the completion of complex tasks. A four-PSD robot calibration device is a laser measuring instrument that uses laser light to irradiate a PSD sensor to accurately measure the position and posture of the robot's end effector, thereby achieving high-precision calibration. However, in the actual application environment, stray light becomes an important factor affecting the calibration accuracy.

[0003] The sources of stray light are extensive. On the one hand, natural light from the surrounding environment, such as sunlight entering the working area through windows, gaps, etc.; on the other hand, artificial light sources in the workplace, such as the light emitted by lighting fixtures, indicator lights of other equipment, etc., may enter the optical path system of the four-PSD robot calibration device at different angles. When these stray lights propagate in the optical path, they will interfere with the main laser, generating additional optical signals on the PSD sensor, resulting in deviations in the output of the PSD sensor.

[0004] Chinese Patent Application No.: "2024119467565", Patent Name: "Fast Acquisition Device for the Position of the Robot Motion Indication Spot Based on Four PSDs", this device is a laser measuring instrument that uses laser light to irradiate a PSD sensor to accurately measure the position and posture of the robot's end effector. The device includes PSD-1, PSD-2, PSD-3, PSD-4, Laser Reflection Structure-1, Laser Reflection Structure-2, Lower Housing, Reference Plate, Power Supply, Signal Processor, Wireless Transmitter, Wireless Data Transceiver, and Host Computer;

[0005] The PSD-1 is fixed below the Laser Reflection Structure-1, the PSD-2 is fixed above the Laser Reflection Structure-1, the PSD-3 is fixed below the Laser Reflection Structure-2, and the PSD-4 is fixed above the Laser Reflection Structure-2; the Laser Reflection Structure-1 and the Laser Reflection Structure-2 are fixed to the reference plate, the reference plate is connected to the lower housing by bolts, the power supply, signal processor, and wireless transmitter are fixed inside the lower housing, the signal processor and the wireless transmitter are connected to the power supply, the wireless transmitter and the wireless data transceiver are transmitted through wireless communication, and the wireless data transceiver is connected to the host computer. The method of the present invention is used for stray light suppression of this device.

[0006] The Chinese patent publication number is "CN 107991064B", and the patent name is "Near backscattered light measurement system resistant to stray light interference". The measurement system includes a sampling device and a measurement device. The sampling device includes a spherical vacuum target chamber and an imaging lens. A target point and a diffuse reflection plate with a target laser channel are arranged in the spherical vacuum target chamber. The diffuse reflection plate is attached to the inner wall of the spherical vacuum target chamber. A measurement window is arranged on the spherical wall of the spherical vacuum target chamber. The near backscattered light generated by the incident target laser is scattered in the opposite direction of the target shooting and then diffusely reflected by the diffuse reflection plate. The diffusely reflected light penetrates the measurement window and then enters the measurement device through the imaging lens. The imaging lens images the diffuse reflection plate on the primary image plane. An isolation screen is arranged on the plane where the primary image plane is located. The isolation screen has a plurality of light passing holes. By setting the isolation screen in the present invention, the possibility of stray light scattered from the inner wall of the target chamber entering the diagnostic optical path is excluded, and the effect of stray light shielding is achieved. However, the incident state of the laser cannot be observed and judged by this device. Summary of the Invention

[0007] In order to solve the problem that the incident state of the laser cannot be observed and judged in the existing calibration device, the present invention proposes a stray light suppression method for a four-PSD robot calibration device.

[0008] The technical solution for the present invention to solve the technical problem is as follows:

[0009] A stray light suppression method for a four-PSD robot calibration device, the method comprising the following steps:

[0010] Step S1: Laser incident angle calibration;

[0011] PSD-1 and PSD-2 are arranged inside the light-shielding cover. The inner surface of the light-shielding cover is evenly coated with light-absorbing paint. The plane mirror and the reflecting mirror are coaxially arranged with the filter. The filter is arranged on the lower surface of the reflecting mirror. Laser L1 is incident on the plane mirror, and a light spot G1 appears on the plane mirror. Through the refraction of the plane mirror, laser L2 is incident on the reflecting mirror, and after being reflected by the reflecting mirror, a reflected laser L3 is formed. A light spot G2 appears on the plane mirror. A part of the laser L4 reflected by the laser L3 incident on the plane mirror is absorbed by the light-absorbing paint. Adjust the incident angle α of the laser L1 until the light spots G1 and G2 presented on the plane mirror coincide. At this time, the laser incident angle calibration is completed;

[0012] Step S2: Stray light filtering process;

[0013] After the laser incident angle calibration, the plane mirror and the reflecting mirror are removed. The laser L1 with stray light A is incident on the filter. The filter blocks the passage of external stray light A. The laser after the laser L1 passes through the filter is L5;

[0014] Step S3: Stray light extinction process;

[0015] The laser L5 enters the inside of the light-shielding cover and is incident on PSD-1. The laser L6 reflected by PSD-1 is absorbed by the extinction paint.

[0016] Advantages of the present invention: The present invention proposes a stray light suppression method for a four-PSD robot calibration device. Through the vertical calibration structure, the incident laser angle can be intuitively adjusted to ensure that the laser is vertically incident, and the problem of observing and judging the incident state of the laser can be solved. At the same time, a filter can cut off stray light outside the required wavelength band, and the inside of the light-shielding cover is coated with extinction paint to absorb stray light generated due to reflection and other reasons, further reducing stray light interference. This method can be widely used in laser measuring instruments that require high-precision spot position information. Description of the Drawings

[0017] Figure 1 It is a schematic diagram of the device based on the stray light suppression method for a four-PSD robot calibration device of the present invention;

[0018] Figure 2 It is a schematic diagram of the optical path principle of the stray light suppression method for a four-PSD robot calibration device of the present invention;

[0019] Figure 3 It is a schematic diagram of the PSD placement position in the embodiment;

[0020] In the figure: 1, light-shielding cover; 2, frustum; 3, through hole; 4, extinction paint; 5, lens barrel; 6, plane mirror; 7, reflector; 8, filter; 9, PSD-1; 10, PSD-2. Detailed Embodiment

[0021] The stray light suppression method for a four-PSD robot calibration device is based on the following device. This device is a laser measuring instrument that uses a laser to irradiate a PSD sensor to accurately measure the position and posture of the end effector of the robot, as Figure 1 shown. The device includes: a light-shielding cover 1, a frustum 2, a through hole 3, extinction paint 4, a lens barrel 5, a plane mirror 6, a reflector 7, and a filter 8. A concave frustum 2 is provided on the light-shielding cover 1. A through hole 3 is provided on the lower surface of the frustum 2. The inner surface of the light-shielding cover 1 is evenly coated with extinction paint 4. PSD-1 9 and PSD-2 10 are provided inside the light-shielding cover 1. A plane mirror 6 is provided at the upper end of the lens barrel 5, and a reflector 7 is provided at the lower end of the lens barrel 5. The lens barrel 5, the plane mirror 6, and the reflector 7 form a component. The inner surface of the lens barrel 5 is evenly coated with extinction paint 4. The plane mirror 5 and the reflector 6 are arranged parallel and coaxially with the filter 8, and the filter 8 is provided on the lower surface of the reflector 6. The filter 8 is provided on the upper surface of the frustum 2.

[0022] The stray light suppression method for a four-PSD robot calibration device, as Figure 2 shown, the specific steps of this method are as follows.

[0023] Step S1: Laser incident angle calibration;

[0024] Place PSD-9 and PSD-10 inside the light-shielding cover 1. The inner surface of the light-shielding cover 1 is evenly coated with light-absorbing paint 4. The plane mirror 6 and the reflecting mirror 7 are coaxially arranged with the filter 8, and the filter 8 is arranged on the lower surface of the reflecting mirror 7. The laser L1 is incident on the plane mirror 6, and a light spot G1 appears on the plane mirror 6. Through the refraction of the plane mirror 6, the laser L2 is incident on the reflecting mirror 7, and after being reflected by the reflecting mirror 7, a reflected laser L3 is formed. A light spot G2 appears on the plane mirror 6. Part of the laser L4 reflected by the laser L3 incident on the plane mirror 6 is absorbed by the light-absorbing paint 4. Adjust the incident angle α of the laser L1 until the light spots G1 and G2 on the plane mirror 6 coincide. At this time, the laser incident angle calibration is completed. The wavelengths of the lasers L1, L2, L3, and L4 are all λ.

[0025] Step S2: Stray light filtering treatment;

[0026] After the laser incident angle is calibrated, remove the lens barrel 5, the plane mirror 6, and the reflecting mirror 7. The laser L1 with stray light A is incident on the filter 8. The filter 8 blocks the passage of external stray light A. The laser L5 after the laser L1 passes through the filter 8 has a wavelength of λ.

[0027] Step S3: Stray light extinction treatment;

[0028] The laser L5 enters the inside of the light-shielding cover 1 and is incident on PSD-9. The laser L6 reflected by PSD-9 is absorbed by the light-absorbing paint 4.

[0029] Example:

[0030] In this example, the selected λ is 650 nm, and the filter 8 is a red glass filter that passes wavelengths above 650 nm and blocks below. A PSD of model DRX-2DPSD-GJD02 is used, with a resolution of 0.002 mm, a linear error of 0.1%, and an effective surface that is a 9 mm * 9 mm square. It can detect the two-dimensional position of the light spot of the pulsed laser beam on the surface of the PSD, as Figure 3 shown. The incident laser L5 is incident on PSD-9, and after being reflected by PSD-10, the laser L7 is incident on PSD-2. The other two PSDs are symmetrically placed with PSD-9 and PSD-10 respectively. Before and after using the present invention, the comparison of the PSD position coordinate data collected is shown in Table 1.

[0031] Table 1

[0032]

[0033]

Claims

1. A method for suppressing stray light in a four-PSD robot calibration device, characterized in that The specific steps of this method are as follows: Step S1: Calibrate the incident angle of light; Place PSD 1 (9) and PSD 2 (10) inside the light-shielding cover (1). The inner surface of the light-shielding cover (1) is evenly coated with light-absorbing paint (4). The plane mirror (6) and the reflecting mirror (7) are coaxially arranged with the filter (8), and the filter (8) is arranged on the lower surface of the reflecting mirror (7). The light L1 is incident on the plane mirror (6), and a light spot G1 appears on the plane mirror (6). Through the refraction of the plane mirror (6), the light L2 is incident on the reflecting mirror (7), and after being reflected by the reflecting mirror (7), a reflected light L3 is formed, and a light spot G2 appears on the plane mirror (6). A part of the light L4 reflected by the light L3 incident on the plane mirror (6) is absorbed by the light-absorbing paint (4). Adjust the incident angle α of the light L1 until the light spots G1 and G2 on the plane mirror (6) coincide. At this time, the calibration of the incident angle of light ends; Step S2: Filter out stray light; After the incident angle of light is calibrated, remove the plane mirror (6) and the reflecting mirror (7); the light L1 with stray light A is incident on the filter (8), and the filter (8) blocks the external stray light A from passing through. The light after the light L1 passes through the filter (8) is L5; Step S3: Eliminate stray light; The light L5 enters the inside of the light-shielding cover (1) and is incident on PSD 1 (9), and the light L6 reflected by PSD 1 (9) is absorbed by the light-absorbing paint (4).

2. The stray light suppression method for the four-PSD robot calibration device according to claim 1, characterized in that, The wavelengths of the lights L1, L2, L3, L4, and L5 are all λ.

3. The stray light suppression method for the four-PSD robot calibration device according to claim 1, wherein The device based on this method includes: a light-shielding cover (1), a frustum (2), a through hole (3), light-absorbing paint (4), a lens barrel (5), a plane mirror (6), a reflecting mirror (7), and a filter (8); a concave frustum (2) is arranged on the light-shielding cover (1), a through hole (3) is arranged on the lower surface of the frustum (2), the inner surface of the light-shielding cover (1) is evenly coated with light-absorbing paint (4), PSD 1 (9) and PSD 2 (10) are arranged inside the light-shielding cover (1), a plane mirror (6) is arranged at the upper end of the lens barrel (5), a reflecting mirror (7) is arranged at the lower end of the lens barrel (5), the lens barrel (5), the plane mirror (6), and the reflecting mirror (7) form a component, the inner surface of the lens barrel (5) is evenly coated with light-absorbing paint (4), the plane mirror (5) and the reflecting mirror (6) are arranged parallel and coaxially with the filter (8), and the filter (8) is arranged on the lower surface of the reflecting mirror (6), and the filter (8) is arranged on the upper surface of the frustum (2).

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