Intelligent high-speed positioning method and positioning structure for CT rotating slip ring

Abstract

This invention discloses a CT rotating slip ring intelligent high-speed positioning method and positioning structure, relating to the field of slip ring positioning technology. It includes a photoelectric encoder, which connects to the slip ring to incorporate slip ring position information into the scan data. The method determines whether or not to accept the scan data based on the position information. A photoelectric sensor with an origin position is positioned on the photoelectric code disk, corresponding to a hole matching the grating on the surface of the light-blocking plate. A photosensitive element is positioned on the side of the photoelectric code disk away from the light source. Light from the light source passes through the grating and the light-blocking plate via a condenser lens and reaches the photosensitive element. The output of the photosensitive element is electrically connected to a signal receiving module via signal transmission. The scan data is then accepted and entered into the calculation unit. The scan data in the calculation unit is the data we need. The slip ring motor can be set to accelerate and decelerate according to its characteristics, reducing electromagnetic interference and cost. After fusing the position information, the scan data will not be misaligned, resulting in pure data.

Description

Technical Field

[0001] This invention relates to the field of slip ring positioning technology, specifically to a CT rotating slip ring intelligent high-speed positioning method and positioning structure. Background Technology

[0002] CT security screening technology is based on CT scanning (X-Ray Computed Tomography, X-CT, or computed tomography). It uses an X-ray beam to scan a layer of a certain thickness of the object being inspected. A detector receives the X-rays that pass through this layer, converts them into visible light, then into electrical signals, and finally into digital signals via an A / D converter. These signals are then input into a computer for processing and imaging. CT scanning technology is based on the property that different materials attenuate X-rays differently. It is supported by the Radon transform and inverse Radon transform as fundamental theories. It reconstructs the image of the object using projection data obtained from scanning the object from different directions. The data obtained from any direction represents the integral of the X-ray attenuation along that path. By calculating and transforming this data, the attenuation coefficient information of that cross-section is obtained, thereby reconstructing the image of that cross-section.

[0003] After many years and generations of development, security CT has now evolved into a multi-slice dual-source spiral CT security inspection machine. The following problems exist in the existing technology: With current technology, the positioning of the slip ring in a security CT scanner is inaccurate: the high-speed slip ring rotates at a speed of about 300 revolutions per minute, or 200 milliseconds per revolution. When the slip ring receives a stop command, the motor needs to decelerate before stopping, so the actual stopping position deviates from the position required by the command. The next starting position will not be at the previous stopping point, resulting in data errors.

[0004] The reasons are due to the following: first, the delay in the command from the calculation control center to the slip ring; and second, the stopping delay of the slip ring motor.

[0005] For example, there is a 5ms delay from when the command is issued by the computer control center to when the slip ring receives the command, and a 5ms delay from when the motor stops moving to when it actually stops, for a total delay of 10ms; while each rotation of the slip ring is 200ms, which means there is a delay of 1 / 20 of a rotation, or 18 degrees.

[0006] One solution is to reverse the motor, but high-speed slip rings rotate in one phase and cannot be reversed, so this solution is not feasible. Therefore, we propose a CT rotary slip ring intelligent high-speed positioning method and positioning structure to solve the above problem. Summary of the Invention

[0007] The purpose of this invention is to provide a CT rotating slip ring intelligent high-speed positioning method and positioning structure to solve the problems mentioned in the background art.

[0008] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: The intelligent high-speed positioning method for CT rotating slip ring provided by this invention includes the following steps: S1: Install the photoelectric encoder on the frame and rotate synchronously with the slip ring. The encoder has 1201 holes, including 1 origin hole and 1200 encoding holes. S2: Install the encoder control board on the rack and connect it to the encoder. The control board is responsible for sending position information data to the host. For every 0.3 degrees of rotation, the control board sends one position information data point. S3: Calibrate the time difference between the scan data and the location information data to bind them. This can be achieved through hardware calibration or by adding a delay to the control board. S4: When the calculation control unit issues a stop command, record the position information data at this time and turn off subsequent scanning data; S5: When the next calculation control unit issues a rotation command, the slip ring begins to accelerate, and the scanning data is turned off. When the slip ring reaches a stable speed, and the position information in the scanning data is the same as the position information at the last stop, the scanning data begins to be adopted and entered into the calculation unit.

[0009] Preferably, the rotating shaft of the photoelectric encoder rotates synchronously with the slip ring, wherein there is one origin hole and the encoding holes are distributed in a circle, and if there are 1200 holes, each hole is 0.3 degrees apart.

[0010] Preferably, the position information data size is 2 bytes, plus CRC, for a total of 4 bytes. The value is 0 when at the origin, 1 when rotated by 0.3 degrees, and 2 when rotated by 0.6 degrees. The FPGA chip in the encoder control board performs the calculation.

[0011] Preferably, the 1200 encoding aperture needs to send a location information data every 0.16ms.

[0012] Preferably, a delay is added to the encoder control board FPGA so that the position information data and its scanning data arrive at the data receiving module simultaneously.

[0013] Preferably, when the calculation control unit issues a stop command, the slip ring will rotate for another 10ms, and the data from those 10ms will no longer be accepted.

[0014] Preferably, during the acceleration process of the drive motor of the slip ring, the scan data is turned off and not adopted before it reaches a stable speed.

[0015] The CT rotating slip ring intelligent high-speed positioning structure includes an optical encoder disk. A rotating shaft for connecting a slip ring is fixedly connected to the center of the optical encoder disk. The rotating shaft moves synchronously with the slip ring. The optical encoder disk and the axis of the rotating shaft coincide. Multiple gratings for light to pass through are opened around the surface of the optical encoder disk. The multiple gratings are evenly distributed around the axis of the optical encoder disk.

[0016] Preferably, a light source and a condenser lens are provided on one side of the photoelectric code disk. The light from the light source passes through the condenser lens and then through the grating. A light-blocking plate is fixedly connected to the side of the photoelectric code disk away from the light source. The surface of the light-blocking plate has holes that match the grating.

[0017] Preferably, a photosensitive element is provided on the side of the photoelectric code disk away from the light source. The light from the light source passes through the condenser lens, the grating, and the light-blocking plate before reaching the photosensitive element. The output end of the photosensitive element is electrically connected to the signal receiving module through signal transmission.

[0018] Compared with existing technologies, one or more of the above technical solutions have the following beneficial effects: This invention adds a photoelectric encoder to the CT gantry and connects it to the CT host via an encoder control board. The number of gratings in the photoelectric encoder disk can be selected according to requirements, achieving high resolutions such as 1200, 1800, and 3600. The photoelectric encoder disk and slip ring move synchronously, and the connection between the rotating shaft and the slip ring is firm, ensuring stable movement. The light source reaches the photosensitive element after passing through a condenser lens, grating, and light-blocking plate, enabling sensitive light signal detection. The photoelectric encoder disk uses a photosensitive element as a signal detector, which has a long service life and stable performance. The output end of the photosensitive element can be electrically connected to the signal receiving module via signal transmission, facilitating data transmission and processing. The uniformly distributed gratings enable high-precision position detection and encoding. By incorporating slip ring position information data, the acceptance or rejection of scan data can be determined based on the position information data, thereby improving the accuracy and reliability of the data.

[0019] The scanned data is then adopted and entered into the computing unit. This means that the scanned data in the computing unit is the data we need. Invalid data caused by the slip ring stopping and restarting is eliminated. The data adoption strategy during the acceleration process of the slip ring motor and after the speed stabilizes ensures that the collected data is stable and effective. Attached Figure Description

[0020] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0021] Figure 1 This is an assembly diagram of the photoelectric encoder and the dual-spiral CT scanner of the present invention.

[0022] Figure 2 This is a schematic diagram of the dual-spiral CT scanner of the present invention.

[0023] Figure 3 This is a schematic diagram of the photoelectric encoder control board structure of the present invention.

[0024] Figure 4 This is a schematic diagram of the photoelectric encoder architecture of the present invention.

[0025] Figure 5 This is a schematic diagram of the photoelectric encoder structure of the present invention.

[0026] Figure 6 This is a flowchart of the computer delay control of the present invention.

[0027] In the picture: 1. Optical encoder; 2. Grating; 3. Rotating shaft; 4. Light-blocking plate; 5. Light source; 6. Condenser lens; 7. Photosensitive element. Detailed Implementation

[0028] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0029] Please see Figures 1-6 This invention provides a CT rotating slip ring intelligent high-speed positioning method and positioning structure. An optical encoder is added to the CT scanner and mounted on the frame. Its rotor rotates synchronously with the slip ring. The encoder has a total of 1201 holes, including one origin hole and 1200 coded holes (or 1800, 3600, etc.). The coded holes are distributed in a circular pattern, with each hole differing by 0.3 degrees (360° / 1200). By incorporating slip ring position information data, the acceptance or rejection of scan data can be determined based on the position information data, thereby improving the accuracy and reliability of the data.

[0030] To allow continued use of the existing machine, an encoder control board was added to the CT scanner gantry. This board is mounted on the gantry and connected to the encoder to send position information data to the host machine. The slip ring sends a data point every 0.3 degrees of rotation to report the position status. The installation and connection of the photoelectric encoder and encoder control board are relatively simple and can be easily integrated with the existing system.

[0031] To quickly calculate the slip ring's position information, a position information data set of 2 bytes, plus CRC, is used, totaling 4 bytes. The value is 0 at the origin, 1 for a 0.3-degree rotation, 2 for a 0.6-degree rotation, and so on. This is calculated by the FPGA chip in the encoder control board. The reason for using an FPGA is that this calculation is simple but requires high speed; with 1200 encoder holes, a position information data set needs to be sent every 0.16ms. The high-frequency position information data allows for fast calculation, meeting real-time requirements.

[0032] To prevent significant delays during data reception, and to calibrate any time differences between the arrival of scanned data and location information data at the data receiving module, the scanned data and location information data are bound together. This time difference is hardware-driven and varies slightly from unit to unit. Calibration can be performed when necessary. This can be achieved by calibrating the time difference and adding delays. Alternatively, a delay can be added to the encoder control board FPGA to ensure that the location information data and its scanned data arrive at the data receiving module simultaneously. This ensures accurate correspondence between the scanned data and location information data, guaranteeing data consistency.

[0033] To prevent erroneous position information from affecting the positioning system, the position information data is remembered when the calculation control unit issues a stop command, and scan data after this position is not included in the calculation unit. As analyzed earlier, although the slip ring will continue to rotate for 10ms, the data is no longer being used, so it will not affect the calculation results. By remembering the stop position information and filtering invalid data, calculation efficiency can be improved and unnecessary computational overhead can be reduced. By eliminating invalid data, the efficiency and accuracy of data processing can be improved, and the load on the calculation unit can be reduced.

[0034] To prevent invalid data from affecting the slip ring's positioning, the slip ring begins to rotate when the calculation control unit issues a rotation command. The slip ring motor undergoes an acceleration process. Before reaching a stable speed, the scanned data remains closed and is not accepted. After reaching a stable speed, and when the position information in the scanned data matches the position information from the previous stop, the scanned data begins to be accepted and entered into the calculation unit. In this way, the scanned data in the calculation unit is the data we need, and invalid data resulting from the slip ring stopping and restarting is eliminated. The acceleration process of the slip ring motor and the data acceptance strategy after stabilizing the speed ensure that the collected data is stable and effective.

[0035] To improve the positioning accuracy of the slip ring, an optical encoder disk 1 is provided. A rotating shaft 3 for connecting the slip ring is fixedly connected to the center of the optical encoder disk 1. The rotating shaft 3 moves synchronously with the slip ring. The axes of the optical encoder disk 1 and the rotating shaft 3 coincide. Multiple gratings 2 for light to pass through are evenly distributed around the axis of the optical encoder disk 1 around its perimeter. A light source 5 and a condenser lens 6 are provided on one side of the optical encoder disk 1. Light from the light source 5 passes through the condenser lens 6 and then through the gratings 2. A light-blocking plate 4 is fixedly connected to the side of the optical encoder disk 1 away from the light source 5. Holes matching the gratings 2 are formed on the surface of the light-blocking plate 4. A photosensitive element 7 is provided on the side of the optical encoder disk 1 away from the light source 5. Light from the light source 5, after passing through the condenser lens 6, the gratings 2, and the light-blocking plate 4, reaches the photosensitive element 7. The output end of component 7 is electrically connected to the signal receiving module via signal transmission. The axis of the photoelectric encoder 1 coincides with that of the rotating shaft 3. The number of gratings 2 can be selected according to requirements, achieving high resolutions such as 1200, 1800, and 3600. The photoelectric encoder 1 moves synchronously with the slip ring, and the connection between the rotating shaft 3 and the slip ring is firm, maintaining a stable motion state. The light source 5 reaches the photosensitive element 7 after passing through the condenser lens 6, grating 2, and light-blocking plate 4, enabling sensitive light signal detection. The photoelectric encoder 1 uses the photosensitive element 7 as a signal detector, which has a long service life and stable performance. The output end of the photosensitive element 7 can be electrically connected to the signal receiving module via signal transmission, facilitating data transmission and processing. The gratings 2 are evenly distributed, enabling high-precision position detection and encoding.

[0036] Working principle Core idea: Incorporate slip ring position information into the scan data, and decide whether to adopt the scan data based on the position information.

[0037] A photoelectric sensor with an origin position is arranged on the photoelectric code disk 1, and corresponding holes matching the grating 2 are opened on the surface of the light-blocking plate 4. The grating 2 is evenly distributed around the axis of the photoelectric code disk 1 (the grating 2 can have 1200, 1800, 3600, etc. to keep the position of the encoding hole coincide). If there are 1200 photoelectric sensors, each is 0.3 degrees. The code holes are distributed in a circle, and the difference between each hole is 0.3 degrees (360° / 1200), which is used to provide position information. Light from light source 5 passes through condenser lens 6 and then through grating 2. A light-blocking plate 4 is fixedly connected to the side of the photoelectric code disk 1 away from light source 5. The surface of the light-blocking plate 4 has holes that match those of grating 2. A photosensitive element 7 is set on the side of the photoelectric code disk 1 away from light source 5. The light from light source 5, after passing through condenser lens 6, grating 2, and light-blocking plate 4, reaches the photosensitive element 7. The output of the photosensitive element 7 is electrically connected to the signal receiving module via signal transmission. 1201 photoelectric signals are input and converted into 4 bytes of position information data for output. A 2-byte position information data is set, plus CRC, for a total of 4 bytes. The value is 0 at the origin, 1 when rotated by 0.3 degrees, 2 when rotated by 0.6 degrees, and so on. This calculation is performed by the FPGA chip in the encoder control board. The reason for using an FPGA is that this calculation is simple but requires high speed. The control board is responsible for sending position information data to the host. It sends one position information data point for every 0.3 degrees of rotation; with 1200 encoder holes, this translates to one position information data point every 0.16 milliseconds. This high-frequency position information data processing speed meets real-time requirements and allows for calibration of the time difference between scan data and position information data. The slip ring sends one data point for every 0.3 degrees of rotation, reporting the current position status. Installing and connecting the photoelectric encoder and encoder control board is relatively simple and allows for easy integration with existing systems. This is achieved through hardware calibration or by adding a delay to the control board. When the calculation control unit issues a stop command, the position information data at that moment is recorded, and subsequent scanning data is stopped. Although the slip ring will continue to rotate for a period of time, this data will not be adopted into the calculation unit. To ensure the accurate correspondence between the scanning data and the position information data, the time difference in the data reception process needs to be calibrated so that the position information data and the scanning data arrive at the data receiving module simultaneously. This ensures the consistency between the scanning data and the position information data. When the calculation control unit issues a rotation command, the slip ring begins to accelerate, while the scanning data remains closed. When the slip ring reaches a stable rotational speed, and the position information in the scanning data matches the previous stopping position, the scanning data begins to be incorporated into the calculation unit. When the calculation control unit issues a stop command, it needs to remember the current position information and close the scanning data after this position, excluding it from the calculation unit. Even if the slip ring continues to rotate for another 10 milliseconds, the data is no longer being incorporated and will not affect the calculation results. By remembering the stopping position information and filtering invalid data, calculation efficiency can be improved, and unnecessary computational overhead can be reduced. The slip ring's scanning data, after fusing position information, will not be misaligned, resulting in clean data and accurate positioning. By adding a photoelectric encoder to the CT scanner and combining it with the encoder control board and photoelectric code disk 1, the accuracy and reliability of the data can be improved, achieving high-precision position detection and encoding. After the scan data is fused with position information, there will be no misalignment, and the data is pure, so that the scan results of the CT scanner can correspond to the detected position, thus improving the accuracy of the generated image.

[0038] In summary, the main advantages of this device are: 1. Slip ring motors can be set to accelerate and decelerate according to their characteristics, reducing electromagnetic interference and cost.

[0039] 2. The scanned data will not be misaligned after the location information is fused, and the data will be pure.

[0040] 3. The function to enable and disable data scanning ensures that the computing center is not affected by interfering data.

[0041] shortcoming: 1. The addition of an encoder and its control board increases the overall wear factor and maintenance difficulty of the machine.

[0042] 2. The software for the computing control center needs to be updated to include a location information processing and time difference calibration module.

[0043] The slip ring position information is incorporated into the scan data, and the decision to accept or reject scan data is based on this position information. Position information is sent via a photoelectric encoder and encoder control board, the time difference is calibrated, and the stop position is remembered. After the slip ring starts, the position information is used to determine whether to accept scan data. The advantages are reduced electromagnetic interference and ensured data purity; the disadvantages are increased equipment and maintenance complexity.

[0044] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the technical scope disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention. The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A CT rotating slip ring intelligent high-speed positioning method, characterized in that, Includes the following steps: S1: Install the photoelectric encoder on the frame and rotate synchronously with the slip ring. The encoder has 1201 holes, including 1 origin hole and 1200 encoding holes. S2: Install the encoder control board on the frame and connect the encoder. The control board is responsible for sending position information data to the host. For every 0.3 degrees of rotation, the control board sends one position information data. S3: Calibrate the time difference between the scan data and the location information data in order to bind them, which can be achieved through hardware calibration or by adding a delay to the control board; S4: When the calculation control unit issues a stop command, record the position information data at this time and turn off subsequent scanning data; S5: When the next calculation control unit issues a rotation command, the slip ring starts to accelerate and the scanning data is turned off. When the slip ring reaches a stable speed and the position information in the scanning data is the same as the position information of the last stop, the scanning data begins to be adopted and enters the calculation unit.

2. The CT rotary slip ring intelligent high speed positioning method according to claim 1, characterized in that, The photoelectric encoder's shaft rotates synchronously with the slip ring. It has one origin hole and the encoding holes are distributed in a circle. If there are 1200 holes, each hole is 0.3 degrees apart.

3. The CT rotary slip ring intelligent high speed positioning method according to claim 1, characterized in that, The position information data is 2 bytes in size, plus CRC, for a total of 4 bytes. The value is 0 when at the origin, 1 when rotated by 0.3 degrees, and 2 when rotated by 0.6 degrees. The FPGA chip in the encoder control board performs the calculation.

4. The intelligent high-speed positioning method for CT rotating slip rings according to claim 2, characterized in that, Each of the 1200 coded holes needs 0.16ms to send a location information data.

5. The intelligent high-speed positioning method for CT rotating slip rings according to claim 3, characterized in that, A delay is added to the encoder control board FPGA so that the position information data and its scanning data arrive at the data receiving module simultaneously.

6. The intelligent high-speed positioning method for CT rotating slip rings according to claim 1, characterized in that, When the computing control unit issues a stop command, the slip ring will rotate for another 10ms, and the data during those 10ms will no longer be accepted.

7. The intelligent high-speed positioning method for CT rotating slip rings according to claim 1, characterized in that, Before the drive motor of the slip ring reaches a stable speed during acceleration, the scan data is closed and not accepted.

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