A method for measuring and controlling the displacement accuracy of an inspection bed and the inspection bed itself.

Abstract

This application discloses a method for measuring and controlling the displacement accuracy of an examination bed, and an examination bed in the field of medical equipment. The method includes: identifying whether the examination bed is slipping based on a comparison of a first difference and a first threshold value between the displacement measurement parameters of the servo motor encoder and the transmission device encoder during the current movement; if slippage exists, performing compensatory movement control on the examination bed based at least on the estimated slippage distance and the first difference value; if no slippage exists and a second difference value between the displacement measurement parameters collected by the transmission device encoder and the displacement sensor is not less than a second threshold value, identifying anomalies in the transmission device encoder and displacement sensor based on the estimated slippage distance and each displacement measurement parameter, and outputting the anomaly identification result. This application achieves accurate detection of the examination bed's displacement accuracy by cross-comparing the displacement measurement parameters collected by each displacement measuring device and realizing slippage detection and anomaly detection of the displacement measuring devices based on the comparison results.

Description

Technical Field

[0001] This application relates to the field of medical equipment technology, and in particular to a method for measuring and controlling the displacement accuracy of an examination bed and an examination bed. Background Technology

[0002] To prevent the examination bed from being unable to be pulled out of the scanning area due to mechanical failure, existing medical imaging equipment uses a clutch to connect the servo motor driving the examination bed to the transmission device. In the event of a servo motor failure, the clutch disconnects the servo motor from the transmission device, allowing the examination bed to be manually removed from the scanning area.

[0003] However, the presence of a clutch causes slippage between the servo motor and the transmission device during normal acceleration or deceleration due to the non-rigid connection of the clutch. This leads to discrepancies between the actual and expected displacement of the examination table, reducing the scanning accuracy of the medical imaging equipment. Therefore, achieving accurate detection of the examination table displacement has become an urgent problem to be solved. Summary of the Invention

[0004] In view of the above problems, this application provides a method for measuring and controlling the displacement accuracy of an inspection bed and an inspection bed itself, so as to achieve the purpose of accurately detecting the displacement accuracy of the inspection bed. The specific solution is as follows:

[0005] The first aspect of this application provides a method for measuring and controlling the displacement accuracy of an inspection bed, including:

[0006] When the inspection bed stops moving, the total mass of the inspection bed during the movement is obtained, as well as the displacement measurement parameters collected by each displacement measuring device of the inspection bed, including a displacement sensor, a servo motor encoder and a transmission device encoder.

[0007] Based on the comparison result of the first difference and the first threshold value of the displacement measurement parameters collected by the servo motor encoder and the transmission device encoder, it is identified whether the inspection bed has a slippage phenomenon. The first threshold value is the upper limit value of the displacement error of the inspection bed.

[0008] In the event of the slippage, the examination bed is subjected to compensatory movement control based at least on the estimated slippage distance and the first difference, wherein the estimated slippage distance corresponds to the total mass.

[0009] In the absence of slippage, a second difference is calculated between the displacement measurement parameters collected by the encoder of the transmission device and the displacement sensor. If the second difference is not less than a second threshold, the sum of the estimated slippage distance and the displacement measurement parameters collected by the servo motor encoder is determined as the theoretical drag distance. Based on the theoretical drag distance, the displacement measurement parameters collected by the encoder of the transmission device and the displacement measurement parameters collected by the servo motor encoder, anomaly identification is performed on the encoder of the transmission device and the displacement sensor, and anomaly identification results are output. The first threshold is greater than the second threshold.

[0010] In one possible implementation, the compensatory movement control of the examination bed, based at least on the slip distance estimate and the first difference, includes:

[0011] If the third difference between the first difference and the estimated slip distance is less than a third threshold, the servo motor of the inspection bed is controlled to run with the third difference as the first compensation distance, and the third threshold is greater than the second threshold.

[0012] If the third difference is not less than the third threshold and the second difference is not less than the second threshold, the displacement measurement parameters of the transmission device encoder are updated to the displacement measurement parameters collected by the displacement sensor, and the difference between the displacement measurement parameters collected by the servo motor encoder and the updated displacement measurement parameters of the transmission device encoder is determined as the second compensation distance. The servo motor of the inspection bed is controlled based on the second compensation distance.

[0013] One possible implementation also includes:

[0014] If the third difference is not less than the third threshold and the second difference is less than the second threshold, the servo motor of the examination bed is controlled to operate at the first compensation distance.

[0015] In one possible implementation, based on the theoretical value of the drag distance, the displacement measurement parameters collected by the encoder of the transmission device, and the displacement measurement parameters collected by the encoder of the servo motor, anomaly identification is performed on the encoder of the transmission device and the displacement sensor, and anomaly identification results are output, including:

[0016] Calculate the fourth difference between the displacement measurement parameters collected by the encoder of the transmission device and the theoretical value of the drag distance, and calculate the fifth difference between the displacement measurement parameters collected by the displacement sensor and the theoretical value of the drag distance;

[0017] If the fourth difference is not less than the third threshold, the output content is the abnormal identification result of the encoder of the transmission device, and the third threshold is greater than the second threshold.

[0018] If the fifth difference is not less than the third threshold, the output content is the abnormality identification result of the displacement sensor.

[0019] In one possible implementation, if the third difference is not less than the third threshold and the second difference is not less than the second threshold, the method further includes:

[0020] The displacement measurement parameters of the encoder of the transmission device are updated to the displacement measurement parameters collected by the displacement sensor.

[0021] In one possible implementation, if the fourth difference is not less than the third threshold, it further includes:

[0022] The displacement measurement parameters of the encoder of the transmission device are updated to the displacement measurement parameters collected by the displacement sensor.

[0023] In one possible implementation, if the fifth difference is not less than the third threshold, it further includes:

[0024] The displacement measurement parameters of the displacement sensor are updated to the displacement measurement parameters collected by the encoder of the transmission device.

[0025] A second aspect of this application provides an inspection bed, comprising: a tray, a pressure sensor, a transmission device, a clutch, a servo motor, a servo motor encoder, a transmission device encoder, a displacement sensor, and a controller for executing a method for measuring and controlling the displacement accuracy of the inspection bed as described in the first aspect and any implementation thereof.

[0026] The displacement sensor is disposed on the non-load-bearing surface of the tray, and the encoder of the transmission device is dynamically connected to the transmission device;

[0027] The tray is connected to the transmission device, and the power input end of the transmission device is connected to the power output end of the servo motor through the clutch.

[0028] The servo motor encoder is electrically connected to the servo motor, and the servo motor, the servo motor encoder, the transmission device encoder, and the displacement sensor are all electrically connected to the controller.

[0029] In one possible implementation, the displacement sensor may include at least the following types: a drawstring sensor, a laser rangefinder, and an inductive displacement sensor.

[0030] In one possible implementation, the transmission device is a lead screw.

[0031] By employing the above technical solution, this application provides a method for measuring and controlling the displacement accuracy of an examination bed, as well as an examination bed itself. This method, when the examination bed stops moving, obtains the total mass of the examination bed during the current movement, and the displacement measurement parameters collected by each displacement measuring device of the examination bed. The displacement measuring devices include a displacement sensor, a servo motor encoder, and a transmission device encoder, thereby achieving the acquisition of displacement measurement parameters from three dimensions: the motor, the transmission device, and the examination bed. Subsequently, by configuring a comparison between a first difference in the displacement measurement parameters collected by the servo motor encoder and the transmission device encoder and a first threshold representing the upper limit of displacement error, the method identifies whether slippage occurs on the examination bed, achieving accurate identification of slippage phenomena affecting the displacement accuracy of the examination bed. Furthermore, by configuring the method to perform compensatory movement control on the examination bed in the event of slippage, at least based on the estimated slippage distance corresponding to the total mass and the first difference, the method avoids the risk of decreased examination bed displacement accuracy due to slippage, thereby reducing the scanning accuracy of medical imaging equipment. Finally, by configuring the system to handle the absence of slippage, a second difference is calculated between the displacement measurement parameters acquired by the transmission encoder and the displacement sensor. If this second difference is not less than a second threshold representing the maximum allowable error range, anomalies are identified in the transmission encoder and displacement sensor based on the theoretical drag distance, the displacement measurement parameters acquired by the transmission encoder, and the displacement measurement parameters acquired by the servo motor encoder. The anomaly identification result is then output. This process enables the identification of anomalies in the transmission encoder or displacement sensor that cause errors, avoiding the risk of cumulative errors caused by these anomalies affecting the subsequent detection accuracy of the inspection bed's displacement. Therefore, this application achieves accurate detection of the inspection bed's displacement accuracy. Attached Figure Description

[0032] The above and other features, advantages, and aspects of the embodiments of this disclosure will become more apparent from the accompanying drawings and the following detailed description. Throughout the drawings, the same or similar reference numerals denote the same or similar elements. It should be understood that the drawings are schematic, and the originals and elements are not necessarily drawn to scale.

[0033] Figure 1 A flowchart illustrating a method for measuring and controlling the displacement accuracy of an inspection bed provided in this application;

[0034] Figure 2 This application provides a schematic diagram of the clinical positioning of an examination bed;

[0035] Figure 3 A flowchart for slippage recognition provided in this application;

[0036] Figure 4 A flowchart of a compensatory movement control system for an examination bed is provided in this application;

[0037] Figure 5 A flowchart for anomaly identification provided in this application;

[0038] Figure 6 A flowchart illustrating a method for measuring and controlling the displacement accuracy of an inspection bed provided in this application;

[0039] Figure 7 A schematic diagram of the structure of an examination bed provided in this application;

[0040] Figure 8 This is a schematic diagram of the structure of a controller provided in this application. Detailed Implementation

[0041] The embodiments of this application are described below with reference to the accompanying drawings. The terminology used in the implementation section of this application is for explaining specific embodiments only and is not intended to limit the scope of this application.

[0042] The embodiments of this application will now be described with reference to the accompanying drawings. Those skilled in the art will recognize that, with technological advancements and the emergence of new scenarios, the technical solutions provided in the embodiments of this application are equally applicable to similar technical problems.

[0043] The terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms are interchangeable where appropriate; this is merely a way of distinguishing objects with the same attributes in the embodiments of this application. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, so that a process, method, system, product, or apparatus that comprises a series of elements is not necessarily limited to those elements, but may include other elements not explicitly listed or inherent to those processes, methods, products, or apparatuses.

[0044] The first aspect of this application provides a method for measuring and controlling the displacement accuracy of an inspection bed, such as... Figure 1 As shown, the method for measuring and controlling the displacement accuracy of the inspection bed includes:

[0045] S101. When the inspection bed stops moving, obtain the total mass of the inspection bed during the movement, as well as the displacement measurement parameters collected by each displacement measuring device of the inspection bed. The displacement measuring device includes a displacement sensor, a servo motor encoder, and a transmission device encoder.

[0046] It should be noted that, in practical applications, the aforementioned examination bed can be an examination bed configured on medical imaging equipment such as computed tomography (CT), single-photon emission computed tomography (SPECT), and positron emission tomography (PET). For example... Figure 2 The diagram shown is a clinical positioning diagram of an examination bed adapted for SPECT equipment.

[0047] It should be noted that in practical applications, the examination bed can be either unloaded or not. When not unloaded, the total mass of the examination bed varies with the weight of the load (e.g., different patients have different weights). Furthermore, the total mass of the examination bed is a significant factor affecting clutch slippage. Therefore, the accuracy of the obtained total mass directly impacts the subsequent measurement and control precision. This application, by configuring the total mass during the current movement, allows each measurement and control operation to be based on the actual total mass of the examination bed during that movement, thus improving the accurate detection and control of the examination bed's displacement.

[0048] It should be noted that, in practical application scenarios, the method for measuring and controlling the displacement accuracy of the inspection bed provided by the first aspect and any implementation thereof of this application can be executed by the controller in the control system of the inspection bed.

[0049] It should be noted that, in practical applications, the aforementioned total mass can be collected by one or more pressure sensors deployed on the surface of the inspection bed or inside the bearing surface. This application does not specify or elaborate on the specific type and number of the aforementioned pressure sensors.

[0050] It should be noted that, in practical applications, the aforementioned servo motor encoder and transmission device encoder are used to convert angular or linear displacement into electrical signals to measure the movement distance of the inspection bed driven by the transmission device and servo motor. Specifically, the aforementioned servo motor encoder and transmission device encoder can be incremental encoders. For each revolution of the power output shaft of the transmission device or servo motor, the aforementioned servo motor encoder and transmission device encoder output an electrical signal. By calculating the number of electrical signals output by the aforementioned servo motor encoder or transmission device encoder at the point where the movement stops and the drag distance corresponding to one electrical signal, the actual drag distance of the servo motor or transmission device can be calculated.

[0051] It should be noted that in practical applications, the aforementioned displacement sensors are non-contact displacement sensors deployed on the inspection bed and moving with it. Various types of displacement sensors can be used, including but not limited to: draw-wire sensors, laser rangefinders, and inductive displacement sensors. Since these displacement sensors do not contact the servo motor or transmission device, the displacement measurement parameters collected by the sensors are not directly affected by slippage. Therefore, this application, by configuring the aforementioned displacement sensors to collect displacement measurement parameters, provides data verification for the servo motor encoder and transmission device encoder during subsequent measurement and control processes, thereby improving the final detection accuracy of the inspection bed's displacement.

[0052] It should be noted that in practical applications, due to design differences among the displacement sensors, servo motor encoders, and transmission device encoders, the dimensions of the obtained displacement measurement parameters differ. Therefore, after obtaining the displacement measurement parameters collected by each displacement measuring device, these parameters can be normalized to eliminate the influence of dimensions on subsequent measurement and control accuracy.

[0053] S102. Based on the comparison result of the first difference and the first threshold of the displacement measurement parameters collected by the servo motor encoder and the transmission device encoder, identify whether the inspection bed is slipping. The first threshold is the upper limit of the displacement error of the inspection bed.

[0054] It should be noted that in practical applications, clutch slippage can lead to differences in the actual dragging distances of the servo motors and transmission devices located on either side. Furthermore, due to the combined effects of device assembly, normal wear, and design redundancy, even without slippage, the actual dragging distances of the servo motors and transmission devices will exhibit differences that do not affect the scanning accuracy of the medical imaging equipment (e.g., a first threshold of 5mm, and the upper limit of the displacement error of the actual dragging distance of the servo motor and transmission device is 5mm). Therefore, this application achieves accurate identification of whether the examination table is slipping by setting the upper limit of the displacement error of the examination table to a first threshold and configuring a comparison between the first difference and the first threshold based on the displacement measurement parameters collected by the servo motor encoder and the transmission device encoder.

[0055] It should be noted that, in practical application scenarios, the implementation of step S102 above may include the following: Figure 3 Steps A1 to A4 are shown.

[0056] Step A1: Calculate the first difference between the displacement measurement parameters acquired by the servo motor encoder and the transmission device encoder. Then trigger step A2.

[0057] Step A2: Determine if the first difference is less than the first threshold. If yes, trigger step A3; otherwise, trigger step A4.

[0058] Step A3: Output the first trigger command indicating that there is no slippage on the inspection bed.

[0059] It should be noted that, in practical application scenarios, step A3 above is a trigger instruction used to trigger step S104 of the method for measuring and controlling the displacement accuracy of the inspection bed provided in the first aspect of this application.

[0060] Step A4: Output a second trigger command indicating that the examination bed is slipping.

[0061] It should be noted that, in practical application scenarios, step A4 above is a trigger instruction used to trigger step S103 of the method for measuring and controlling the displacement accuracy of the inspection bed provided in the first aspect of this application.

[0062] S103. In the event of slippage, the examination bed shall be subject to compensatory movement control based at least on the estimated slippage distance and the first difference, wherein the estimated slippage distance corresponds to the total mass.

[0063] It should be noted that, in practical applications, the aforementioned estimated slip distance can be obtained by calibrating the slippage phenomenon of the inspection bed under different total masses using a constant servo motor speed. The estimated slip distances for different total masses can be stored in the inspection bed's control system, allowing for lookup of the corresponding slip distance estimate based on the total mass during application.

[0064] It should be noted that in practical applications, the mass of the examination bed changes with the weight of the patient it carries, leading to increased resistance between the examination bed and the transmission device. This, in turn, causes changes in the degree of clutch slippage and the slippage distance. The first difference between the displacement measurement parameters collected by the servo motor encoder and the transmission device encoder represents the actual slippage distance. Therefore, this application configures the examination bed to perform compensatory movement control in the presence of slippage, based at least on the estimated slippage distance and the first difference, thereby avoiding the risk of decreased compensatory movement control accuracy due to malfunctions in the servo motor encoder or the transmission device encoder.

[0065] S104. In the absence of slippage, calculate the second difference between the displacement measurement parameters collected by the encoder of the transmission device and the displacement sensor. If the second difference is not less than the second threshold, determine the sum of the estimated slippage distance and the displacement measurement parameters collected by the servo motor encoder as the theoretical value of the drag distance. Based on the theoretical value of the drag distance, the displacement measurement parameters collected by the encoder of the transmission device and the displacement measurement parameters collected by the servo motor encoder, perform anomaly identification on the encoder of the transmission device and the displacement sensor, and output the anomaly identification result. The first threshold is greater than the second threshold.

[0066] It should be noted that, in practical applications, the second threshold mentioned above is the maximum allowable error range of the displacement measurement parameters collected by the encoder and displacement sensor of the transmission device, which can be obtained through calibration tests on a test bed that does not experience clutch slippage.

[0067] It should be noted that in practical applications, since both the encoder and displacement sensor of the transmission device are located on the moving parts of the examination bed (such as the transmission device or the load-bearing surface), and the servo motor is usually securely mounted on the fixed parts of the examination bed (such as the bed frame or the mounting surface of the examination bed) to avoid excessive centrifugal force and vibration, the encoder and displacement sensor of the transmission device will be subjected to more vibration and stress, increasing the risk of inaccuracy and error of the encoder and / or displacement sensor. A complete movement process of the examination bed includes moving the patient into the scanning area and moving the patient out of the scanning area after the scan is completed. In real-world scenarios, the examination bed may perform multiple complete movement processes continuously (such as when multiple patients are queuing for examination). In this case, if the encoder and / or displacement sensor of the transmission device are already inaccurate and have generated errors, the errors will accumulate continuously during the multiple complete movements of the examination bed, thereby reducing the accuracy of the displacement measurement parameters collected by the encoder and / or displacement sensor of the transmission device, and thus reducing the efficiency of the examination bed displacement accuracy detection. Therefore, this application, by configuring the second difference between the displacement measurement parameters collected by the encoder and displacement sensor of the transmission device under the condition that there is no slippage, and under the condition that the second difference is not less than the second threshold of the maximum allowable error range, based on the theoretical value of the drag distance, the displacement measurement parameters collected by the encoder of the transmission device, and the displacement measurement parameters collected by the servo motor encoder, performs anomaly identification on the encoder and displacement sensor of the transmission device and outputs the anomaly identification result. This enables the anomaly identification of the encoder or displacement sensor of the transmission device that has anomalies that cause errors, thereby improving the subsequent detection accuracy of the displacement accuracy of the inspection bed.

[0068] This application configures the system to obtain the total mass of the examination bed during its current movement, as well as the displacement measurement parameters collected by each displacement measuring device of the examination bed, when the bed stops moving. The displacement measuring devices include a displacement sensor, a servo motor encoder, and a transmission device encoder, thereby acquiring displacement measurement parameters for the motor, transmission device, and examination bed. Subsequently, by configuring a comparison between a first difference in the displacement measurement parameters collected by the servo motor encoder and the transmission device encoder and a first threshold representing the upper limit of displacement error, the application identifies whether the examination bed is slipping, achieving accurate identification of slippage that affects the accuracy of the examination bed's displacement. Furthermore, by configuring the system to perform compensatory movement control on the examination bed in the event of slippage, based at least on the estimated slippage distance corresponding to the total mass and the first difference, the application avoids the risk of decreased examination bed displacement accuracy due to slippage, thereby reducing the scanning accuracy of the medical imaging equipment. Finally, by configuring the system to handle the absence of slippage, a second difference is calculated between the displacement measurement parameters acquired by the transmission encoder and the displacement sensor. If this second difference is not less than a second threshold representing the maximum allowable error range, anomalies are identified in the transmission encoder and displacement sensor based on the theoretical drag distance, the displacement measurement parameters acquired by the transmission encoder, and the displacement measurement parameters acquired by the servo motor encoder. The anomaly identification result is then output. This process enables the identification of anomalies in the transmission encoder or displacement sensor that cause errors, avoiding the risk of cumulative errors caused by these anomalies affecting the subsequent detection accuracy of the inspection bed's displacement. Therefore, this application achieves accurate detection of the inspection bed's displacement accuracy.

[0069] In one possible implementation, the examination bed is subjected to compensatory movement control based at least on the estimated slip distance and the first difference, including:

[0070] If the third difference between the first difference and the estimated slip distance is less than the third threshold, the servo motor of the inspection bed is controlled to run with the third difference as the first compensation distance, and the third threshold is greater than the second threshold.

[0071] If the third difference is not less than the third threshold and the second difference is not less than the second threshold, the displacement measurement parameters of the transmission device encoder are updated to the displacement measurement parameters collected by the displacement sensor, and the difference between the displacement measurement parameters collected by the servo motor encoder and the updated displacement measurement parameters of the transmission device encoder is determined as the second compensation distance. The operation of the servo motor of the inspection bed is controlled based on the second compensation distance.

[0072] It should be noted that, in practical application scenarios, the aforementioned third threshold can be the maximum allowable error between the estimated slip distance obtained through calibration tests and the first difference, assuming that there are no abnormalities in the servo motor encoder and the transmission device encoder, when slippage occurs.

[0073] Since the first threshold is the upper limit of the displacement error of the inspection bed, by configuring the third difference between the first difference and the estimated slip distance to be less than the third threshold, the servo motor of the inspection bed is controlled to run with the third difference as the first compensation distance, thereby avoiding the risk of further reduction in the displacement accuracy of the inspection bed due to overcompensation.

[0074] It should be noted that in practical applications, the estimated slippage distance is obtained by calibrating the inspection bed under different total masses using a constant servo motor speed to detect slippage. Therefore, its accuracy is higher than the first difference mentioned above. The presence of slippage indicates that the displacement measurement parameters collected by the transmission encoder are inaccurate due to the slippage. A second difference not less than the second threshold indicates that the error in the displacement measurement parameters collected by the transmission encoder and displacement sensor exceeds the maximum allowable error range. A third difference not less than the third threshold indicates that the error between the first difference and the estimated slippage distance is large, and when slippage is known to exist, the displacement measurement parameters collected by the transmission encoder are inaccurate and have a large error. In summary, when slippage exists, the second difference is not less than the second threshold, and the third difference is not less than the third threshold, the risk of an abnormality in the transmission encoder is high. Therefore, this application updates the displacement measurement parameters of the transmission device encoder to the displacement measurement parameters collected by the displacement sensor when the third difference is not less than the third threshold and the second difference is not less than the second threshold. The difference between the displacement measurement parameters collected by the servo motor encoder and the updated displacement measurement parameters of the transmission device encoder is determined as the second compensation distance. The operation of the inspection bed's servo motor is controlled based on this second compensation distance. This avoids the risk of over- or under-compensation caused by using the compensation distance generated from the displacement measurement parameters collected by the transmission device encoder to compensate the servo motor's movement when the accuracy of the transmission device encoder is questionable. In one possible implementation, it also includes:

[0075] If the third difference is not less than the third threshold and the second difference is less than the second threshold, the servo motor of the inspection bed is controlled to run with the first compensation distance.

[0076] It should be noted that in practical applications, when the second difference is less than the second threshold, it indicates that the error of the displacement measurement parameters collected by the encoder and displacement sensor of the transmission device does not exceed the maximum value of the allowable error range. However, when the third difference is not less than the third threshold, it indicates that the error between the first difference and the estimated slippage distance is large. Therefore, it can be concluded that the third difference being not less than the third threshold is due to a large difference between the degree of slippage and the calibration test. In this case, by configuring the servo motor of the inspection bed to operate with the first compensation distance, since the first compensation distance is collected by each displacement measurement device without abnormalities, it reflects the current real situation of the inspection bed, thereby ensuring the accuracy of the compensated movement control of the servo motor.

[0077] In one possible implementation, the above-mentioned method of compensating for movement control of the examination bed based at least on the slippage distance estimate and the first difference can be:

[0078] like Figure 4 The diagram shown is a flowchart of a compensatory movement control system for an examination bed. The specific operation steps are as follows:

[0079] Step S401: Calculate the third difference between the first difference and the estimated slip distance, and calculate the second difference between the displacement measurement parameters collected by the encoder and displacement sensor of the transmission device. Then trigger step S402.

[0080] Step S402: Determine whether the third difference is less than the third threshold. If yes, then trigger step S403; otherwise, trigger step S404.

[0081] In step S403, the servo motor of the inspection bed is controlled to run with the third difference as the first compensation distance.

[0082] Step S404: Determine whether the second difference is less than the second threshold. If yes, then trigger step S405; otherwise, trigger step S406.

[0083] Step S405: Control the servo motor of the inspection bed to run at the first compensation distance.

[0084] Step S406: Update the displacement measurement parameters of the encoder of the transmission device to the displacement measurement parameters collected by the displacement sensor, and determine the difference between the displacement measurement parameters collected by the servo motor encoder and the updated displacement measurement parameters of the encoder of the transmission device as the second compensation distance, and control the operation of the servo motor of the inspection bed based on the second compensation distance.

[0085] In one possible implementation, based on the theoretical value of the drag distance, the displacement measurement parameters collected by the encoder of the transmission device, and the displacement measurement parameters collected by the encoder of the servo motor, anomaly identification is performed on the encoder and displacement sensor of the transmission device, and the anomaly identification results are output, including:

[0086] The sum of the displacement measurement parameters collected by the servo motor encoder and the estimated slip distance is used as the estimated current position of the inspection machine.

[0087] Calculate the fourth difference between the displacement measurement parameters collected by the encoder of the transmission device and the current position estimate, and calculate the fifth difference between the displacement measurement parameters collected by the displacement sensor and the current position estimate;

[0088] If the fourth difference is not less than the third threshold, the output is the abnormal identification result of the encoder abnormality of the transmission device, and the third threshold is greater than the second threshold.

[0089] If the fifth difference is not less than the third threshold, the output will be the abnormal identification result of the displacement sensor.

[0090] It should be noted that in practical applications, the transmission encoder is typically installed at the power output end of the transmission device to collect displacement measurement parameters in a manner that follows the power output end. Since the displacement sensor moves with the examination bed, it is usually installed on the moving parts of the examination bed (such as the bed board or near the power output end). The transmission encoder bears all the mechanical stress generated when the examination bed moves, including axial force, radial force, and torque. During the start-up, stop, acceleration, and deceleration of the examination bed, these stresses change frequently, which may cause wear, deformation, or even breakage of mechanical components such as bearings and shafts inside the encoder. In contrast, the servo motor encoder mainly bears the relatively small torque generated when the motor is running, and its mechanical stress environment is relatively better. Furthermore, during the operation of the examination bed, vibrations and impacts are generated due to the movement of the bed and the patient's getting on and off. These vibrations and impacts are directly transmitted to the transmission encoder and displacement sensor, which may cause loosening or damage to the optical components (such as code disks and gratings) or electronic components inside the encoder, resulting in minor errors. In contrast, servo motors and servo motor encoders are usually installed in relatively stable positions, and the servo motor encoder is subjected to less vibration and impact. When the examination bed undergoes multiple complete movements with short intervals or without interruption over a long period, the minute errors of the transmission encoder or displacement sensor accumulate continuously. This accumulation, exceeding a third threshold, affects the accuracy of the examination bed's displacement detection. Therefore, this application configures the system to identify anomalies in the transmission encoder and displacement sensor based on the theoretical value of the drag distance, displacement measurement parameters collected by the transmission encoder, and displacement measurement parameters collected by the servo motor encoder, under conditions without slippage. This pre-detection of potentially malfunctioning transmission encoders or displacement sensors prevents the cumulative error from affecting the accuracy of the examination bed's displacement detection.

[0091] It should be noted that in practical applications, the first threshold is the upper limit of the displacement error of the examination bed. Exceeding the first threshold will affect the scanning accuracy of the medical imaging equipment. However, the absence of slippage when the first difference is less than the first threshold does not mean that slippage has never occurred. It only means that slippage when the first difference is less than the first threshold will not affect the scanning accuracy of the medical imaging equipment. Even in the absence of slippage, slight slippage can still cause a small error in the displacement measurement parameters collected by each displacement measurement device. Therefore, this application configures the sum of the displacement measurement parameters collected by the servo motor encoder and the estimated slippage distance to be determined as the theoretical value of the dragging distance of the examination bed when there is no slippage. This ensures that the obtained theoretical dragging distance is closest to the actual displacement distance of the examination bed, thereby providing a highly accurate comparison benchmark for subsequent anomaly identification.

[0092] It should be noted that in practical applications, there are multiple ways to implement the above-mentioned anomaly identification of the encoder and displacement sensor of the transmission device. Here, one example is provided:

[0093] like Figure 5 The diagram shows a flowchart for anomaly detection. The specific steps are as follows:

[0094] Step S501: The sum of the displacement measurement parameters collected by the servo motor encoder and the estimated slip distance is determined as the theoretical value of the drag distance of the inspection bed. Step S502 is then triggered.

[0095] Step S502: Calculate the fourth difference between the displacement measurement parameters collected by the encoder of the transmission device and the theoretical value of the drag distance, and calculate the fifth difference between the displacement measurement parameters collected by the displacement sensor and the theoretical value of the drag distance. Then trigger step S503.

[0096] Step S503: Determine whether the fourth difference is less than the third threshold. If not, trigger step S504; if yes, trigger step S505.

[0097] Step S504 outputs the abnormal identification result of the encoder abnormality of the transmission device.

[0098] Step S505: Determine whether the fifth difference is less than the third threshold. If not, trigger step S506; if yes, end the process.

[0099] Step S506 outputs the anomaly identification result of the displacement sensor malfunction.

[0100] It should be noted that in practical applications, steps S503 and S505 can be performed simultaneously or sequentially. This application does not impose excessive restrictions on the execution order of steps S503 and S505. In one possible implementation, when the third difference is not less than the third threshold and the second difference is not less than the second threshold, the following is also included:

[0101] The output will display a message indicating an error in the encoder of the transmission device.

[0102] In one possible implementation, if the fourth difference is not less than the third threshold, it also includes:

[0103] Update the displacement measurement parameters of the encoder of the transmission device to the displacement measurement parameters collected by the displacement sensor.

[0104] It should be noted that in practical applications, the risk of anomalies in the transmission encoder is high when the fourth difference is not less than the third threshold, leading to the risk of accumulated errors. Therefore, this application updates the displacement measurement parameters of the transmission encoder to the displacement measurement parameters collected by the displacement sensor when the fourth difference is not less than the third threshold, thereby correcting potential accumulated errors in the transmission encoder and improving the detection accuracy of the inspection bed displacement.

[0105] In one possible implementation, if the fifth difference is not less than the third threshold, it also includes:

[0106] Update the displacement measurement parameters of the displacement sensor to the displacement measurement parameters collected by the encoder of the transmission device.

[0107] It should be noted that in practical applications, the displacement sensor has a higher risk of malfunction when the fifth difference is not less than the third threshold, leading to the risk of accumulated errors. Therefore, this application updates the displacement measurement parameters of the displacement sensor to the displacement measurement parameters collected by the encoder of the transmission device when the fifth difference is not less than the third threshold, thereby correcting the potential accumulated errors of the displacement sensor and improving the detection accuracy of the inspection bed displacement.

[0108] To facilitate understanding of the method for measuring and controlling the displacement accuracy of the inspection bed provided by the first aspect and any implementation thereof of this application, an explanation is provided here in conjunction with one possible implementation of this application:

[0109] like Figure 6 The diagram shows a flowchart of a method for measuring and controlling the displacement accuracy of an inspection bed. The specific operation steps are as follows: Step S601, control the servo motor to drive the inspection bed to the target position for this movement. And trigger step S602.

[0110] In step S602, if the inspection bed stops moving, obtain the total mass of the inspection bed during this movement, as well as the displacement measurement parameters collected by each displacement measuring device of the inspection bed. Then trigger step S603.

[0111] Step S603: Calculate the first difference between the displacement measurement parameters acquired by the servo motor encoder and the transmission device encoder. Then trigger step S604.

[0112] Step S604: Determine whether the first difference is less than the first threshold. If not, trigger step S605; if yes, trigger step S606.

[0113] Step S605: Calculate the third difference between the first difference and the estimated slip distance, and calculate the second difference between the displacement measurement parameters collected by the encoder and displacement sensor of the transmission device. Then trigger step S607.

[0114] Step S606: Calculate the second difference between the displacement measurement parameters acquired by the encoder and displacement sensor of the transmission device. Then trigger step S612.

[0115] Step S607: Determine whether the third difference is less than the third threshold. If yes, trigger step S608; otherwise, trigger step S609.

[0116] In step S608, the servo motor of the inspection bed is controlled to run with the third difference as the first compensation distance.

[0117] Step S609: Determine whether the second difference is less than the second threshold. If yes, trigger step S610; otherwise, trigger step S611.

[0118] In step S610, the servo motor of the inspection bed is controlled to run at the first compensation distance.

[0119] Step S611: Update the displacement measurement parameters of the transmission device encoder to the displacement measurement parameters collected by the displacement sensor, and determine the difference between the displacement measurement parameters collected by the servo motor encoder and the updated displacement measurement parameters of the transmission device encoder as the second compensation distance. Control the operation of the servo motor of the inspection bed based on the second compensation distance, and output a prompt message indicating that the transmission device encoder is abnormal.

[0120] Step S612: Determine whether the second difference is less than the second threshold. If yes, then trigger step S613; otherwise, trigger step S614.

[0121] Step S613, End.

[0122] Step S614: The sum of the displacement measurement parameters collected by the servo motor encoder and the estimated slip distance is determined as the theoretical value of the drag distance of the inspection bed. Step S615 is then triggered.

[0123] Step S615: Calculate the fourth difference between the displacement measurement parameters collected by the encoder of the transmission device and the theoretical value of the drag distance, and calculate the fifth difference between the displacement measurement parameters collected by the displacement sensor and the theoretical value of the drag distance. Then trigger step S616.

[0124] Step S616: Determine whether the fourth difference is less than the third threshold. If not, trigger step S617; if yes, trigger step S618.

[0125] Step S617: Update the displacement measurement parameters of the encoder of the transmission device to the displacement measurement parameters collected by the displacement sensor, and output the anomaly identification result of the encoder of the transmission device. Trigger step S613.

[0126] Step S618: Determine whether the fifth difference is less than the third threshold. If not, trigger step S619; if yes, trigger step S613.

[0127] Step S619: Update the displacement measurement parameters of the displacement sensor to the displacement measurement parameters collected by the encoder of the transmission device, and output the anomaly identification result of the displacement sensor malfunction. Trigger step S613.

[0128] It should be noted that, in practical application scenarios, steps S601 and S602 are one possible implementation of step S101 as shown in Figure 1. Steps S603 and S604 are one possible implementation of step S102 as shown in Figure 1. Steps S605 and S607 to S611 are one possible implementation of step S103 as shown in Figure 1. Steps S606 and S612 to S619 are one possible implementation of step S104 as shown in Figure 1.

[0129] A second aspect of this application provides an inspection bed, as shown in FIG7. The inspection bed includes: a tray 701, a pressure sensor 702, a transmission device 703, a clutch 704, a servo motor 705, a servo motor encoder 706, a transmission device encoder 707, a displacement sensor 708, and a controller 709 for executing a method for measuring and controlling the displacement accuracy of the inspection bed as provided in the first aspect and any implementation thereof.

[0130] The displacement sensor 708 is disposed on the non-load-bearing surface of the tray 701, the encoder 707 of the transmission device is dynamically connected to the transmission device 703, and the pressure sensor 702 is disposed on the load-bearing surface or inside the tray 701.

[0131] The pallet 701 is connected to the transmission device 703, and the power input end of the transmission device 703 is connected to the power output end of the servo motor 705 through the clutch 704.

[0132] The servo motor encoder 706 is electrically connected to the servo motor 705. The pressure sensor 702, servo motor 705, servo motor encoder 706, transmission device encoder 707, and displacement sensor 708 are all electrically connected to the controller 709.

[0133] It should be noted that, in actual application scenarios, the aforementioned tray 701 is a structure used to support the object to be scanned or the patient. Its bearing surface is the tray surface that contacts the object to be scanned or the patient (such as the upper surface relative to the examination bed mounting plane), and its non-bearing surface is the tray surface that does not contact the object to be scanned or the patient (such as the lower surface relative to the examination bed mounting plane or the side of the examination bed).

[0134] It should be noted that in practical applications, the pressure sensor 702 is used to detect the pressure applied to the bearing surface of the tray 701, which is applied by the patient or the object to be scanned. Since the mass of the examination bed itself does not change, this application obtains the total mass of the examination bed during a single movement by configuring the pressure sensor on or inside the bearing surface of the tray 701, collecting the pressure applied to the bearing surface of the tray 701, and summing this pressure with the mass of the examination bed itself. The arrangement, type, and number of the pressure sensors can be configured in various ways, for example, as described above... Figure 7 In the schematic diagram of the examination bed structure shown, the pressure sensor 702 includes two capacitive pressure sensors, which are arranged side by side inside the tray 701 to detect pressure evenly and improve the accuracy of total mass acquisition.

[0135] In one possible implementation, the pressure sensor 702 described above includes at least the following types: piezoresistive pressure sensor, capacitive pressure sensor, and piezoelectric pressure sensor. This application does not impose excessive limitations on the type of pressure sensor described above.

[0136] It should be noted that in practical applications, the aforementioned transmission device 703 can be of various types, including but not limited to: lead screw, synchronous belt, and rack and pinion gear set. When the transmission device 703 is a lead screw, the encoder 707 can be mounted on one end of the lead screw and rotate with the lead screw. When the transmission device 703 is a synchronous belt, the encoder 707 can be mounted on the driven gear of the synchronous belt and rotate with the driven gear. When the transmission device 703 is a rack and pinion gear set, the encoder 707 can be mounted on the gear meshing with the rack and pinion gear and rotate with the gear.

[0137] It should be noted that this application configures the transmission device encoder 707 to be connected to the transmission device 703, thereby using the transmission device encoder 707 to collect displacement measurement parameters of the transmission device 703 dragging the pallet 701 during one movement.

[0138] It should be noted that in practical applications, the aforementioned clutch 704 can be a manual clutch or an electronically controlled clutch. This application does not impose too many restrictions or elaborate on the specific type of clutch 704.

[0139] It should be noted that, in practical applications, the aforementioned servo motor encoder 706 is used to collect the number of rotations of the servo motor 705 and convert it into displacement measurement parameters that enable the servo motor 705 to move the tray 701.

[0140] It should be noted that, in practical applications, the displacement sensor 708 is used to directly acquire the displacement measurement parameters of the pallet 701 during a single movement. Since the displacement measurement parameters acquired by the displacement sensor 708 are the parameters of the pallet 701's own movement and are not affected by the clutch 704, they can be used as a reference for the displacement measurement parameters acquired by the servo motor encoder 706 and the transmission device encoder 707.

[0141] It should be noted that this application configures the pressure sensor 702, servo motor 705, servo motor encoder 706, transmission device encoder 707, and displacement sensor 708 to be electrically connected to the controller 709, and configures the controller 709 to execute the method for measuring and controlling the displacement accuracy of the inspection bed as provided in the first aspect and any implementation thereof, thereby achieving accurate detection and compensation control of the displacement accuracy of the inspection bed, and improving the detection accuracy and compensation control accuracy of the displacement accuracy of the inspection bed.

[0142] In one possible implementation, the displacement sensor 708 described above includes at least the following types: a drawstring sensor, a laser rangefinder, and an inductive displacement sensor.

[0143] It should be noted that in practical applications, when the displacement sensor 708 is a pull-string sensor, the fixed end of the pull-string can be connected to a fixed point near the output shaft of the servo motor 705.

[0144] In one possible implementation, the aforementioned transmission device is a lead screw.

[0145] This application also provides a controller in its embodiments. (See reference...) Figure 8The diagram illustrates a structural schematic suitable for implementing the controller in the embodiments of this application. The controller in the embodiments of this application may include, but is not limited to, fixed terminals such as the control terminal of a medical scanning device, a laptop computer, a PDA (Personal Digital Assistant), a PAD (Tablet Computer), a desktop computer, etc. Figure 8 The controller shown is merely an example and should not impose any limitation on the functionality and scope of use of the embodiments of this application.

[0146] like Figure 8 As shown, the controller may include a processing device (e.g., a central processing unit, a graphics processing unit, etc.) 801, which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM) 802 or a program loaded from a storage device 808 into a random access memory (RAM) 803. When the controller is powered on, the RAM 803 also stores various programs and data required for controller operation. The processing device 801, ROM 802, and RAM 803 are interconnected via a bus 804. An input / output (I / O) interface 805 is also connected to the bus 804.

[0147] Typically, the following devices can be connected to I / O interface 805: input devices 806 including, for example, touchscreens, touchpads, keyboards, mice, cameras, microphones, servo motors, drive encoders, etc.; output devices 807 including, for example, liquid crystal displays (LCDs), speakers, vibrators, etc.; storage devices 808 including, for example, memory cards, hard drives, etc.; and communication devices 809. Communication device 809 allows the controller to communicate wirelessly or wiredly with other devices to exchange data. Although Figure 8 A controller with various devices is shown; however, it should be understood that implementation or possession of all the devices shown is not required. More or fewer devices may be implemented alternatively.

[0148] This application also provides a computer program product including computer-readable instructions, which, when executed on a controller, cause the controller to implement any of the methods for measuring and controlling the displacement accuracy of a test bed provided in this application.

[0149] This application also provides a computer-readable storage medium carrying one or more computer programs. When the one or more computer programs are executed by a controller, the controller can implement any of the methods for measuring and controlling the displacement accuracy of the inspection bed provided in this application.

[0150] It should also be noted that the device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. In addition, in the device embodiment drawings provided in this application, the connection relationship between modules indicates that they have a communication connection, which can be implemented as one or more communication buses or signal lines.

[0151] Through the above description of the embodiments, those skilled in the art can clearly understand that this application can be implemented by means of software plus necessary general-purpose hardware, or it can be implemented by special-purpose hardware including application-specific integrated circuits, special-purpose CPUs, special-purpose memory, special-purpose components, etc. Generally, any function performed by a computer program can be easily implemented by corresponding hardware, and the specific hardware structure used to implement the same function can also be diverse, such as analog circuits, digital circuits, or special-purpose circuits. However, for this application, software program implementation is more often the preferred implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a readable storage medium, such as a computer floppy disk, USB flash drive, mobile hard disk, ROM, RAM, magnetic disk, or optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, training equipment, or network device, etc.) to execute the methods described in the various embodiments of this application.

[0152] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product.

[0153] The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions may be transmitted from one website, computer, training device, or data center to another website, computer, training device, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium may be any available medium that a computer can store or a data storage device such as a training device or data center that integrates one or more available media. The available media may be magnetic media (e.g., floppy disks, hard disks, magnetic tapes), optical media (e.g., DVDs), or semiconductor media (e.g., solid-state drives (SSDs)).

Claims

1. A method for measuring and controlling the displacement accuracy of an inspection bed, characterized in that, include: When the inspection bed stops moving, the total mass of the inspection bed during the movement is obtained, as well as the displacement measurement parameters collected by each displacement measuring device of the inspection bed, including a displacement sensor, a servo motor encoder and a transmission device encoder. Based on the comparison result of the first difference and the first threshold value of the displacement measurement parameters collected by the servo motor encoder and the transmission device encoder, it is identified whether the inspection bed has a slippage phenomenon. The first threshold value is the upper limit value of the displacement error of the inspection bed. In the event of the slippage, the examination bed is subjected to compensatory movement control based at least on the estimated slippage distance and the first difference, wherein the estimated slippage distance corresponds to the total mass. In the absence of slippage, a second difference is calculated between the displacement measurement parameters collected by the encoder of the transmission device and the displacement sensor. If the second difference is not less than a second threshold, the sum of the estimated slippage distance and the displacement measurement parameters collected by the servo motor encoder is determined as the theoretical drag distance. Based on the theoretical drag distance, the displacement measurement parameters collected by the encoder of the transmission device, and the displacement measurement parameters collected by the servo motor encoder... The encoder and displacement sensor of the transmission device are subjected to anomaly identification, and the anomaly identification result is output, wherein the first threshold is greater than the second threshold.

2. The method for measuring and controlling the displacement accuracy of an inspection bed according to claim 1, characterized in that, The compensation movement control of the examination bed based at least on the estimated slip distance and the first difference includes: If the third difference between the first difference and the estimated slip distance is less than a third threshold, the servo motor of the inspection bed is controlled to run with the third difference as the first compensation distance, and the third threshold is greater than the second threshold. If the third difference is not less than the third threshold and the second difference is not less than the second threshold, the displacement measurement parameters of the transmission device encoder are updated to the displacement measurement parameters collected by the displacement sensor, and the difference between the displacement measurement parameters collected by the servo motor encoder and the updated displacement measurement parameters of the transmission device encoder is determined as the second compensation distance. The servo motor of the inspection bed is controlled based on the second compensation distance.

3. The method for measuring and controlling the displacement accuracy of an inspection bed according to claim 2, characterized in that, Also includes: If the third difference is not less than the third threshold and the second difference is less than the second threshold, the servo motor of the examination bed is controlled to operate at the first compensation distance.

4. The method for measuring and controlling the displacement accuracy of an inspection bed according to claim 1, characterized in that, Based on the theoretical value of the drag distance, the displacement measurement parameters collected by the encoder of the transmission device, and the displacement measurement parameters collected by the encoder of the servo motor, the system performs anomaly identification on the encoder of the transmission device and the displacement sensor, and outputs the anomaly identification results, including: Calculate the fourth difference between the displacement measurement parameters collected by the encoder of the transmission device and the theoretical value of the drag distance, and calculate the fifth difference between the displacement measurement parameters collected by the displacement sensor and the theoretical value of the drag distance; If the fourth difference is not less than the third threshold, the output content is the abnormal identification result of the encoder of the transmission device, and the third threshold is greater than the second threshold; If the fifth difference is not less than the third threshold, the output content is the abnormality identification result of the displacement sensor.

5. The method for measuring and controlling the displacement accuracy of an inspection bed according to claim 2, characterized in that, If the third difference is not less than the third threshold and the second difference is not less than the second threshold, the method further includes: The displacement measurement parameters of the encoder of the transmission device are updated to the displacement measurement parameters collected by the displacement sensor.

6. The method for measuring and controlling the displacement accuracy of an inspection bed according to claim 4, characterized in that, If the fourth difference is not less than the third threshold, the method further includes: The output content is a prompt message indicating that the encoder of the transmission device is malfunctioning.

7. The method for measuring and controlling the displacement accuracy of an inspection bed according to claim 4, characterized in that, If the fifth difference is not less than the third threshold, the method further includes: The displacement measurement parameters of the displacement sensor are updated to the displacement measurement parameters collected by the encoder of the transmission device.

8. An examination bed, characterized in that, include: The device includes a tray, a pressure sensor, a transmission device, a clutch, a servo motor, a servo motor encoder, a transmission device encoder, a displacement sensor, and a controller for performing the measurement and control method for the displacement accuracy of the inspection bed as described in claims 1 to 7. The displacement sensor is disposed on the non-load-bearing surface of the tray, the encoder of the transmission device is dynamically connected to the transmission device, and the pressure sensor is disposed on the load-bearing surface or inside the tray. The tray is connected to the transmission device, and the power input end of the transmission device is connected to the power output end of the servo motor through the clutch. The servo motor encoder is electrically connected to the servo motor, and the pressure sensor, the servo motor, the servo motor encoder, the transmission device encoder, and the displacement sensor are all electrically connected to the controller.

9. The examination bed according to claim 8, characterized in that, The displacement sensors include at least the following types: rope sensors, laser rangefinders, and inductive displacement sensors.

10. The examination bed according to claim 8, characterized in that, The transmission device is a lead screw.

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