Liquid scintillation spectrometer sample grabbing device and grabbing method

Abstract

The present invention provides a liquid scintillation spectrometer sample grabbing device and grabbing method, which at least includes a moving rod and a suction cup installed at the bottom of the moving rod. The moving rod moves under the drive of a three-axis motor, and the suction cup adsorbs and fixes the sample bottle under the action of a vacuum pump; the top of the spring is connected and fixed to the moving rod, and the bottom of the spring is connected and fixed to the suction cup; the two ends of the displacement sensor are connected and fixed to the two ends of the spring, and the deformation of the spring is synchronously fed back to the displacement sensor, and the displacement sensor collects the deformation of the spring through circuit conversion; a single-chip microcomputer is simultaneously connected to the vacuum pump, the three-axis motor and the displacement sensor, and the spring deformation data collected by the displacement sensor is transmitted to the single-chip microcomputer, and the single-chip microcomputer controls the opening and closing of the vacuum pump and the operation of the three-axis motor. The present application also provides a collision detection method and a method for reliably grabbing samples in conjunction with control technology, thereby preventing the sample bottle from colliding with foreign objects during movement and damaging the sample bottle.

Description

Technical Field

[0001] The invention provides a liquid scintillation spectrometer sample grabbing device and grabbing method, belonging to the technical field of radioactive detection instruments. Background Art

[0002] In the nuclear radiation measurement industry, liquid scintillation spectrometers, as a beta-ray detection device, have a wide range of applications, such as determining the age of archaeological artifacts, detecting radioactivity in nuclear wastewater, detecting nuclear contamination in seafood, and medical examinations. Liquid scintillation spectrometers often take a long time to measure samples, and the samples to be tested generally need to be queued for testing. To ensure accurate measurement, the samples must be prepared and kept away from light for a period of time. Therefore, the automatic sample replacement function is almost a standard feature of liquid scintillation spectrometers. To improve detection efficiency, sample bottles are often made of glass containers, which are fragile. Since the samples are mostly radioactive substances, once the sample bottle breaks, it will cause great economic losses and safety issues. Therefore, the automatic sampling system must be stable and reliable, and it must also be able to continuously process as many samples as possible.

[0003] Currently, the largest sample capacity for liquid scintillation spectrometers (hereinafter referred to as liquid scintillation spectrometers) is 430 slots for 20mL sample bottles. There are two common sample loading methods for liquid scintillation instruments: bottom loading, which involves transporting the sample to the bottom of the measurement position and then using a moving rod to move it to the measurement position. Top loading, which involves transporting the sample to the top of the measurement position and then using a moving rod to suck it up and move it to the measurement position. The method of grabbing samples using a moving rod, as the name suggests, uses a three-dimensional motion motor to move a sampling device consisting of a rod and a suction cup to any position within a three-dimensional space. This method has the advantage of allowing sampling from any position within the space without moving other samples or the sample tray, which greatly improves space utilization, easily increases the number of samples, and easily facilitates the temporary insertion of samples to be tested. However, this method also has significant disadvantages: the sample being grabbed is unprotected during movement, and any mishap in grabbing the sample can cause the sample bottle to break.

[0004] Traditional liquid scintillator automated sampling systems often employ a fixed-position sampling method with no feedback. The sample tray is positioned in a fixed position. To retrieve the sample, the motion rod moves a fixed step to retrieve it. To inject the sample, the motion rod moves a fixed step to transport the sample to the measurement position. This fixed-position sampling method lacks the ability to detect when the motion rod has reached the sample position or eliminate errors, leading to frequent stops during long-term operation. Furthermore, because the measurement position requires the detector, plastic scintillator, reflective layer, and shielding, the space at the measurement location is confined, often barely large enough for a sample vial. Any minor deviation or error during operation can cause the sample vial to collide, which, if uncontrolled, can lead to sample vial breakage. Traditional liquid scintillator designs employ springs as a buffer to mitigate contact errors. However, this solution only prevents collisions caused by single errors and often requires frequent zeroing to ensure reliability. This adds unnecessary motion and introduces additional operational risks.

[0005] Furthermore, existing reports on the use of a moving rod to grab samples do not yet include a design for stacking samples, where two or more samples are stacked on top of each other in a single sample tray. This method offers the highest space efficiency and significant advantages, accommodating the largest number of samples within a fixed space. However, stacking for sample placement is currently unavailable in the art. Summary of the Invention

[0006] The present application provides a liquid scintillation spectrometer sample grabbing device and grabbing method, which solves the shortcomings of the existing technology. The present application uses a motion rod + spring + displacement sensor + suction system to form a grabbing device, adds a collision detection structure design, and provides a collision detection method and how to cooperate with control technology to achieve a reliable sample grabbing process, thereby avoiding the sample bottle from colliding with foreign objects during movement and damaging the sample bottle.

[0007] The technical solutions adopted to achieve the above-mentioned purpose of the present invention are:

[0008] A liquid scintillation spectrometer sample grabbing device includes at least a moving rod and a suction cup mounted at the bottom of the moving rod. The moving rod is driven by a three-axis motor to move, and the suction cup adsorbs and fixes the sample bottle under the action of a vacuum pump. The device also includes:

[0009] A spring, wherein the top of the spring is connected and fixed to the motion rod, and the bottom of the spring is connected and fixed to the suction cup;

[0010] The two ends of the displacement sensor are fixedly connected to the two ends of the spring. The deformation of the spring is synchronously fed back to the displacement sensor, and the displacement sensor collects the deformation of the spring through circuit conversion;

[0011] The single chip microcomputer is connected to the vacuum pump, the three-axis motor and the displacement sensor at the same time. The spring deformation data collected by the displacement sensor is transmitted to the single chip microcomputer, and the single chip microcomputer controls the opening and closing of the vacuum pump and the operation of the three-axis motor.

[0012] Furthermore, the movement rod is a hollow metal tube, and an air pipe is provided between the vacuum pump and the suction cup, and the air pipe passes through the interior of the metal tube and the interior of the spring.

[0013] Furthermore, the displacement sensor is connected in series with a voltage divider resistor and is grounded. The displacement sensor and the spring are compressed and deformed synchronously. In the compressed state, the resistance of the displacement sensor itself decreases, thereby reducing the voltage at both ends. The displacement sensor is connected to the ADC interface built into the microcontroller and transmits the voltage signal to the microcontroller.

[0014] Furthermore, the microcontroller is provided with a USART serial port, through which the microcontroller is connected to the three-axis motor and sends instructions; the microcontroller is also provided with an IO interface, through which the microcontroller controls the MOS tube to drive the electromagnetic relay to turn on and off to realize the opening and closing of the vacuum pump.

[0015] This application also provides a sample grabbing method based on the above-mentioned liquid scintillation spectrometer sample grabbing device, comprising the following steps:

[0016] The S1 microcontroller receives the injection command and sends the command to the three-axis motor through the microcontroller's serial port. The three-axis motor drives the motion rod to move directly above the sample bottle to be taken;

[0017] The S2 single-chip computer sends a command to the three-axis motor, and the three-axis motor drives the motion rod to descend. The single-chip computer stores a pre-set touch determination step length a, and the value of the touch determination step length a corresponds to the distance from the suction cup to the top of the sample bottle. During the descent process, the single-chip computer calls the real-time descent step length x of the motion rod. If the displacement sensor does not sense the deformation of the spring when ax≥10mm, the three-axis motor continues to drive the motion rod to descend, and executes step S3; if the displacement sensor senses the deformation of the spring when ax≥10mm, it is determined that a foreign object has been hit. At this time, the single-chip computer immediately sends a command to the three-axis motor, and the three-axis motor stops driving the motion rod to descend to avoid damage caused by squeezing, and executes step S7 to end the injection task;

[0018] S3 The three-axis motor continuously drives the motion rod to descend. If the displacement sensor senses deformation of the spring when |xa| is less than 10mm, it is determined that the suction cup has touched the sample bottle. At this time, the single-chip microcomputer sends a command to the three-axis motor to stop driving the motion rod to descend and controls the vacuum pump to start. After the suction cup grabs the sample bottle, step S4 is executed; if the displacement sensor does not sense deformation of the spring when |xa| is less than 10mm, the three-axis motor continuously drives the motion rod to descend until the displacement sensor senses deformation of the spring. At this time, it is determined that there is no sample bottle below, causing the suction cup to touch the sample plate. At this time, the single-chip microcomputer immediately sends a command to the three-axis motor, and the three-axis motor stops driving the motion rod to descend to avoid damage to the suction cup caused by squeezing, and step S7 is executed to end the sampling task;

[0019] After the S4 suction cup grabs the sample bottle, the single-chip microcomputer sends a command to the three-axis motor. Driven by the three-axis motor, the motion rod grabs the sample bottle and first rises and then moves to the detection position;

[0020] The S5 single-chip computer sends a command to the three-axis motor, which drives the motion rod to descend. During the descent, the displacement sensor senses whether the spring is deformed in real time. When the displacement sensor senses the spring deformation, it determines that the bottom of the sample bottle has touched the bottom surface of the detection position. At this time, the single-chip computer immediately sends a command to the three-axis motor, and the three-axis motor stops driving the motion rod to descend to avoid damage caused by squeezing. The single-chip computer then controls the vacuum pump to turn off, and the suction cup releases its grip on the sample bottle, leaving the sample bottle at the detection position.

[0021] After the S6 suction cup releases its grip, the microcontroller sends a command to the three-axis motor. Driven by the three-axis motor, the motion rod first rises and then moves to the top of the next sample bottle to be taken.

[0022] S7 loops through steps S2-S6 until all the sample bottles are injected, thus ending the injection task.

[0023] Furthermore, in steps S3 and S5, when it is determined that the suction cup touches the sample bottle or the bottom of the sample bottle touches the bottom surface of the detection position, the motion rod is controlled to continue to descend 2 mm. If the displacement sensor senses further contraction of the spring, it is determined that the suction cup is in good contact with the sample bottle or the sample bottle has touched the bottom well.

[0024] Furthermore, in step S4, when the motion rod grabs the sample bottle and moves it to the detection position, the displacement sensor senses in real time whether the spring is deformed. When the displacement sensor senses that the spring is deformed, it is determined that the sample bottle grasped by the suction cup has touched a foreign object. At this time, the microcontroller immediately sends an instruction to the three-axis motor, and the three-axis motor stops driving the motion rod to avoid the sample bottle from being broken, and executes step S7 to end the sampling task.

[0025] Furthermore, when the displacement sensor senses deformation of the spring, in order to avoid misjudgment, the displacement sensor continues to detect for 200ms. If the displacement sensor senses that the deformation of the spring continues to increase during the continuous detection process, it is determined that a touch has occurred.

[0026] Furthermore, in step S3, when the sample bottles are stacked, if the displacement sensor senses spring deformation when |xa| is less than 10 mm, it is determined that the suction cup has touched the sample bottle. At this time, the single-chip microcomputer sends a command to the three-axis motor to stop driving the motion rod downward and controls the vacuum pump to start. After the suction cup grabs the upper sample bottle, step S4 is executed.

[0027] If the displacement sensor does not sense the deformation of the spring when |xa| is less than 10mm, the three-axis motor continues to drive the motion rod downward; if the displacement sensor senses the deformation of the spring when |xah| is less than 10mm, it is determined that the suction cup has touched the sample bottle on the lower layer, and h is the height of the sample bottle; at this time, the microcontroller sends a command to the three-axis motor to stop driving the motion rod downward and control the vacuum pump to start, and the suction cup grabs the sample bottle on the lower layer and then executes step S4.

[0028] Furthermore, in step S3, if the displacement sensor does not sense the deformation of the spring when xah≥10mm, the three-axis motor continues to drive the motion rod down until the displacement sensor senses the deformation of the spring. At this time, it is determined that there is no sample bottle below, causing the suction cup to touch the sample plate. At this time, the microcontroller immediately sends an instruction to the three-axis motor, and the three-axis motor stops driving the motion rod down to avoid damage to the suction cup caused by squeezing, and executes step S7 to end the sampling task.

[0029] Compared with the prior art, the liquid scintillation spectrometer sample grabbing device and grabbing method provided by the present application have the following advantages: 1. The present application creatively adds a displacement sensor design to the liquid scintillation injection system. When the relative position of the displacement sensor changes within the sensor range, the resistance of the sensor will change accordingly, and the change in resistance can reflect the change in position. In the present application, the displacement sensor and the two ends of the spring are fixed, so that the change in the displacement sensor can reflect the deformation of the spring. The change in the displacement sensor can be sent to the single-chip microcomputer through circuit conversion to form a closed-loop control. During grabbing, when the moving rod touches the sample bottle, the spring at the contact end of the moving rod will contract, and the displacement sensor will feed back the spring contraction information to the single-chip microcomputer. The single-chip microcomputer can then determine whether the moving rod is in contact with the sample bottle, thereby ensuring that the sample is correctly grabbed.

[0030] 2. This application can prevent the sample bottle from being damaged by foreign objects during movement. When the motion rod grabs the sample bottle, the spring at the contact end of the motion rod will contract when the sample bottle hits something. The displacement sensor feeds back the spring contraction information to the single-chip microcomputer. The single-chip microcomputer can determine that the sample bottle has touched a foreign object, realize sample bottle collision detection, and stop the movement in time to avoid the sample bottle from being broken. The foreign object may be the edge of the sample tray, the edge of the injection port, or a sample repeatedly placed in the same position. Therefore, this application also has the functions of detecting and preventing multiple samples from being placed in the measurement position, detecting whether there are samples in the sample tray, and preventing the sample tray from being loaded with excessive samples.

[0031] 3. The present application can also support a method for grasping stacked sample bottles. Since collision detection is provided in the present application, sample bottles can be detected at any height through collision detection, thereby realizing stacked sampling. During specific sampling, the sample bottles at the bottom will trigger collision detection due to the obstruction of the bottom of the sample tray, and the sample bottles on the upper layer will trigger collision detection due to the obstruction of the sample bottles on the lower layer, thereby triggering the single-chip microcomputer to control whether to lay out and whether to sample. The single-chip microcomputer records the movement step length of the motion rod as an aid, and can clearly determine which layer of sample bottles the currently touched sample bottle belongs to through the fixed height of the sample bottle. Therefore, the grasping device and grasping method provided in the present application support stacking, thereby further achieving the purpose of higher space utilization and a larger number of sample bottles. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A schematic diagram of the structure of the sample grabbing device for liquid scintillation spectrometer provided in this application;

[0033] Figure 2 A diagram of the modular components of the liquid scintillation spectrometer sample grabbing device provided in this application;

[0034] Figure 3 A circuit diagram of the sample grabbing device for the liquid scintillation spectrometer provided in this application;

[0035] Figure 4 The overall flow chart of the sample grabbing method provided in this application;

[0036] Figure 5 A flowchart of collision detection in the sample grabbing method provided in this application;

[0037] Figure 6 Schematic diagram of the stacked sample bottles in Example 2.

[0038] In the figure: 1-movement rod, 2-suction cup, 3-spring, 4-displacement sensor, 5-sample bottle, 6-sample tray. DETAILED DESCRIPTION

[0039] The present application is described in detail below with reference to the accompanying drawings and specific embodiments.

[0040] The mechanical structure of the liquid scintillation spectrometer sample grabbing device provided in this embodiment is as follows: Figure 1 As shown, the device comprises the following components: a motion rod 1 and a suction cup 2 mounted at the bottom of the motion rod 1. The suction cup 2 secures the sample bottle 5 under the action of a vacuum pump. The motion rod 1 is driven by a three-axis motor to move. The top of the spring 3 is fixedly connected to the motion rod 1, and the bottom of the spring 3 is fixedly connected to the suction cup 2. The motion rod 1 is a hollow metal tube. An air pipe is provided between the vacuum pump and the suction cup 2, passing through the interior of the metal tube and the interior of the spring 3. A displacement sensor 4 is fixedly connected to both ends of the spring 3. The deformation of the spring 3 is synchronously fed back to the displacement sensor 4, which collects the deformation of the spring 3 through circuit conversion.

[0041] The module settings of the microcontroller are as follows Figure 2 As shown, the single chip microcomputer is connected to the vacuum pump, three-axis motor and displacement sensor at the same time. The circuit diagram is as follows Figure 3 As shown, the displacement sensor collects spring deformation data and transmits it to the microcontroller, which controls the vacuum pump's on / off state and the three-axis motor's operation. The displacement sensor is connected in series with a voltage divider resistor connected to ground. The displacement sensor compresses and deforms synchronously with the spring. In the compressed state, the displacement sensor's resistance decreases, reducing the voltage across its terminals. The displacement sensor is connected to the microcontroller's built-in ADC interface and transmits voltage signals to the microcontroller. The microcontroller also includes a USART serial port, which connects to the three-axis motor and sends commands. The microcontroller also has an I / O interface, which controls the MOSFET that drives the electromagnetic relay to turn the vacuum pump on and off.

[0042] Example 1 In this example, a single-layer sample bottle is used as an example to describe the sample grabbing method of the liquid scintillation spectrometer provided. Figure 4 As shown, this embodiment includes the following steps:

[0043] The S1 microcontroller receives the injection command and sends the command to the three-axis motor through the microcontroller's serial port. The three-axis motor drives the motion rod to move directly above the sample bottle to be taken;

[0044] The S2 microcontroller sends instructions to the three-axis motor, and the three-axis motor drives the motion rod to descend. The microcontroller stores the pre-set touch determination step a. The value of the touch determination step a corresponds to the distance from the suction cup to the top of the sample bottle. Therefore, in theory, by controlling the motion rod to descend step a, it can basically move to the vicinity of the sample bottle (taking into account the existence of errors).

[0045] During the descent process, the microcontroller retrieves the real-time descent step length x of the motion rod. If the displacement sensor does not sense spring deformation when ax ≥ 10 mm, the three-axis motor continues to drive the motion rod downward, and step S3 is executed.

[0046] If the displacement sensor senses deformation of the spring when ax≥10mm, it is determined that a foreign object has been hit. At this time, the microcontroller immediately sends a command to the three-axis motor, and the three-axis motor stops driving the motion rod to descend to avoid damage caused by squeezing, and executes step S7 to end the sampling task; at this time, the staff needs to open the liquid scintillation spectrometer sampling device, find out the cause of the abnormal collision and solve it, and then reset it to zero and restart the grabbing and sampling.

[0047] In step S3, the three-axis motor continuously drives the motion rod downward. If the displacement sensor senses deformation of the spring when |xa| is less than 10 mm, it is determined that the suction cup has touched the sample bottle. The motion rod is then controlled to continue to descend by 2 mm. If the displacement sensor senses further contraction of the spring, it is determined that the suction cup and the sample bottle are in good contact. The single-chip microcomputer then sends a command to the three-axis motor to stop driving the motion rod downward and controls the vacuum pump to start. After the suction cup grabs the sample bottle, step S4 is executed.

[0048] If the displacement sensor does not sense the deformation of the spring when |xa| is less than 10mm, the three-axis motor continues to drive the motion rod downward until the displacement sensor senses the deformation of the spring. At this time, it is determined that there is no sample bottle below, causing the suction cup to touch the sample plate. At this time, the microcontroller immediately sends a command to the three-axis motor, and the three-axis motor stops driving the motion rod downward to avoid damage to the suction cup caused by squeezing, and executes step S7 to end the sampling task; this step indicates that all sampling has been completed, and all sample bottles on the sample plate have been sampled.

[0049] After the S4 suction cup grabs the sample bottle, the single-chip microcomputer sends a command to the three-axis motor. Driven by the three-axis motor, the motion rod grabs the sample bottle and first rises and then moves to the detection position. During this process, the displacement sensor senses whether the spring is deformed in real time. When the displacement sensor senses that the spring is deformed, it determines that the sample bottle grabbed by the suction cup has touched a foreign object. At this time, the single-chip microcomputer immediately sends a command to the three-axis motor. The three-axis motor stops driving the motion rod to avoid the sample bottle from being smashed, and executes step S7 to end the sampling task. At this time, the staff needs to open the liquid scintillation spectrometer sampling device, find out the cause of the abnormal collision and solve it, and then reset it to zero and restart the sampling.

[0050] The S5 microcontroller sends a command to the three-axis motor, which drives the motion rod downward. During the descent, the displacement sensor senses whether the spring is deformed in real time. If the displacement sensor senses spring deformation, it determines that the bottom of the sample bottle has touched the bottom surface of the detection position. At this time, the motion rod is controlled to continue to descend 2mm. If the displacement sensor senses further contraction of the spring, it is determined that the sample bottle has bottomed out. At this time, the microcontroller immediately sends a command to the three-axis motor, which stops driving the motion rod downward to avoid damage caused by squeezing. The microcontroller then controls the vacuum pump to turn off, and the suction cup releases its grip on the sample bottle, leaving the sample bottle at the detection position.

[0051] After the S6 suction cup releases its grip, the microcontroller sends a command to the three-axis motor. Driven by the three-axis motor, the motion rod first rises and then moves to the top of the next sample bottle to be taken.

[0052] S7 loops through steps S2-S6 until all the sample bottles are injected, thus ending the injection task.

[0053] In the above steps, when a collision is detected, that is, when the displacement sensor senses the deformation of the spring, a collision detection is required to avoid misjudgment. The collision detection process is as follows: Figure 5 As shown, because the displacement sensor is fixed at both ends of the spring, the spring remains uncompressed and the displacement sensor value remains unchanged when no object is in contact. However, when an object is in contact, the spring is compressed, and the displacement sensor value decreases. To prevent false positives, the sensor detects a decrease in the displacement sensor value for 200ms to ensure reliability. If the displacement sensor value continues to decrease during this continuous detection process (indicating a continued increase in spring deformation), a touch is detected. This approach prevents false positives caused by random sensor drift or accidental jumps.

[0054] Example 2 In this example, the double-layer sample bottles are stacked as an example to illustrate the provided liquid scintillation spectrometer sample grabbing method in detail. The state of the double-layer sample bottles stacked is referred to Figure 6 As shown, the specific steps in this embodiment are basically the same as those in Example 1, except that in step S3:

[0055] In step S3, when the sample bottles are stacked in a double-layer arrangement, if the displacement sensor senses spring deformation when |xa| is less than 10 mm, it is determined that the suction cup has touched the upper sample bottle. At this time, the single-chip microcomputer sends a command to the three-axis motor to stop driving the motion rod downward and controls the vacuum pump to start. After the suction cup grabs the upper sample bottle, step S4 is executed.

[0056] If the displacement sensor does not sense the deformation of the spring when |xa| is less than 10 mm, the three-axis motor continues to drive the motion rod downward; if the displacement sensor senses the deformation of the spring when |xah| is less than 10 mm, it is determined that the suction cup has touched the sample bottle on the lower layer, where h is the height of the sample bottle, which is 30 mm in this embodiment; at this time, the single-chip microcomputer sends a command to the three-axis motor to stop driving the motion rod downward and controls the vacuum pump to start, and the suction cup grabs the sample bottle on the lower layer and then executes step S4.

[0057] If the displacement sensor does not sense spring deformation when xah ≥ 10 mm, the three-axis motor continues to drive the motion rod downward until the displacement sensor senses spring deformation. At this point, it is determined that there are no sample bottles below, causing the suction cup to touch the sample tray. The microcontroller immediately sends a command to the three-axis motor, causing it to stop driving the motion rod downward to avoid damage to the suction cup caused by squeezing. Step S7 is then executed to end the injection task. This step indicates that all injections have been completed and all sample bottles on the sample tray have been injected.

[0058] Example 3 This application also supports stacking of three or more sample bottles. Taking the stacking of three sample bottles as an example, the provided liquid scintillation spectrometer sample grabbing method is described in detail. The specific steps in this embodiment are basically the same as those in Example 1, except that in step S3:

[0059] In step S3, when the sample bottles are stacked in a double-layer arrangement, if the displacement sensor senses spring deformation when |xa| is less than 10 mm, it is determined that the suction cup has touched the upper sample bottle. At this time, the single-chip microcomputer sends a command to the three-axis motor to stop driving the motion rod downward and controls the vacuum pump to start. After the suction cup grabs the upper sample bottle, step S4 is executed.

[0060] If the displacement sensor does not sense the deformation of the spring when |xa| is less than 10 mm, the three-axis motor continues to drive the motion rod downward; if the displacement sensor senses the deformation of the spring when |xah| is less than 10 mm, it is determined that the suction cup has touched the sample bottle in the middle layer, where h is the height of the sample bottle, which is 30 mm in this embodiment; at this time, the single-chip microcomputer sends a command to the three-axis motor to stop driving the motion rod downward and controls the vacuum pump to start, and the suction cup grabs the sample bottle in the lower layer and then executes step S4.

[0061] If the displacement sensor does not sense the deformation of the spring when |xah| is less than 10mm, the three-axis motor continues to drive the motion rod downward; if the displacement sensor senses the deformation of the spring when |xa-2h| is less than 10mm, it is determined that the suction cup has touched the sample bottle on the lower layer; at this time, the single-chip microcomputer sends a command to the three-axis motor to stop driving the motion rod downward and controls the vacuum pump to start. After the suction cup grabs the sample bottle on the lower layer, step S4 is executed.

[0062] If the displacement sensor does not sense spring deformation when xa - 2h ≥ 10mm, the three-axis motor continues to drive the motion rod downward until the displacement sensor senses spring deformation. At this point, it is determined that there are no sample bottles below, causing the suction cup to touch the sample tray. The microcontroller immediately sends a command to the three-axis motor, causing it to stop driving the motion rod downward to avoid damage to the suction cup caused by squeezing. Step S7 is then executed to end the injection task. This step indicates that all injections have been completed and all sample bottles on the sample tray have been injected.

Claims

1. A sample grabbing method based on a liquid scintillation spectrometer sample grabbing device, the liquid scintillation spectrometer sample grabbing device comprising at least a motion rod and a suction cup mounted at the bottom of the motion rod, the motion rod being driven by a three-axis motor to move, and the suction cup being operated by a vacuum pump to securely hold a sample bottle in place by suction, the device further comprising: a spring, the top of the spring being fixedly connected to the motion rod, and the bottom of the spring being fixedly connected to the suction cup; a displacement sensor, the ends of the displacement sensor being fixedly connected to the ends of the spring, the deformation of the spring being synchronously fed back to the displacement sensor, and the displacement sensor collecting the deformation of the spring through circuit conversion; The single-chip microcomputer is connected to the vacuum pump, the three-axis motor and the displacement sensor. The spring deformation data collected by the displacement sensor is transmitted to the single-chip microcomputer, and the single-chip microcomputer controls the opening and closing of the vacuum pump and the operation of the three-axis motor; It is characterized by: The sample grabbing method comprises the following steps: The S1 microcontroller receives the injection command and sends the command to the three-axis motor through the microcontroller's serial port. The three-axis motor drives the motion rod to move directly above the sample bottle to be taken; The S2 single-chip computer sends a command to the three-axis motor, and the three-axis motor drives the motion rod to descend. The single-chip computer stores a pre-set touch determination step length a, and the value of the touch determination step length a corresponds to the distance from the suction cup to the top of the sample bottle. During the descent process, the single-chip computer calls the real-time descent step length x of the motion rod. If the displacement sensor does not sense the deformation of the spring when ax≥10mm, the three-axis motor continues to drive the motion rod to descend, and executes step S3; if the displacement sensor senses the deformation of the spring when ax≥10mm, it is determined that a foreign object has been hit. At this time, the single-chip computer immediately sends a command to the three-axis motor, and the three-axis motor stops driving the motion rod to descend to avoid damage caused by squeezing, and executes step S7 to end the injection task; S3 The three-axis motor continuously drives the motion rod to descend. If the displacement sensor senses deformation of the spring when |xa| is less than 10mm, it is determined that the suction cup has touched the sample bottle. At this time, the single-chip microcomputer sends a command to the three-axis motor to stop driving the motion rod to descend and controls the vacuum pump to start. After the suction cup grabs the sample bottle, step S4 is executed; if the displacement sensor does not sense deformation of the spring when |xa| is less than 10mm, the three-axis motor continuously drives the motion rod to descend until the displacement sensor senses deformation of the spring. At this time, it is determined that there is no sample bottle below, causing the suction cup to touch the sample plate. At this time, the single-chip microcomputer immediately sends a command to the three-axis motor, and the three-axis motor stops driving the motion rod to descend to avoid damage to the suction cup caused by squeezing, and step S7 is executed to end the sampling task; After the S4 suction cup grabs the sample bottle, the single-chip microcomputer sends a command to the three-axis motor. Driven by the three-axis motor, the motion rod grabs the sample bottle and first rises and then moves to the detection position; The S5 single-chip computer sends a command to the three-axis motor, which drives the motion rod to descend. During the descent, the displacement sensor senses whether the spring is deformed in real time. When the displacement sensor senses the spring deformation, it determines that the bottom of the sample bottle has touched the bottom surface of the detection position. At this time, the single-chip computer immediately sends a command to the three-axis motor, and the three-axis motor stops driving the motion rod to descend to avoid damage caused by squeezing. The single-chip computer then controls the vacuum pump to turn off, and the suction cup releases its grip on the sample bottle, leaving the sample bottle at the detection position. After the S6 suction cup releases its grip, the microcontroller sends a command to the three-axis motor. Driven by the three-axis motor, the motion rod first rises and then moves to the top of the next sample bottle to be taken. S7 loops through steps S2-S6 until all the sample bottles are injected, thus ending the injection task.

2. The sample grabbing method according to claim 1, characterized in that: The motion rod is a hollow metal tube. An air pipe is provided between the vacuum pump and the suction cup. The air pipe passes through the interior of the metal tube and the interior of the spring.

3. The sample grabbing method according to claim 1, characterized in that: The displacement sensor is connected in series with a voltage divider resistor and is grounded. The displacement sensor and the spring are compressed and deformed synchronously. In the compressed state, the resistance of the displacement sensor itself decreases, thereby reducing the voltage at both ends. The displacement sensor is connected to the ADC interface built into the microcontroller and transmits the voltage signal to the microcontroller.

4. The sample grabbing method according to claim 1, characterized in that: The single-chip microcomputer is equipped with a USART serial port, through which the single-chip microcomputer is connected to the three-axis motor and sends instructions; the single-chip microcomputer is also equipped with an IO interface, through which the single-chip microcomputer controls the MOS tube to drive the electromagnetic relay to turn on and off to realize the opening and closing of the vacuum pump.

5. The sample grabbing method according to claim 1, characterized in that: In steps S3 and S5, when it is determined that the suction cup has touched the sample bottle or the bottom of the sample bottle has touched the bottom surface of the detection position, the motion rod is controlled to continue to descend 2 mm. If the displacement sensor senses further contraction of the spring, it is determined that the suction cup is in good contact with the sample bottle or the sample bottle has touched the bottom well.

6. The sample grabbing method according to claim 1, characterized in that: In step S4, when the motion rod grabs the sample bottle and moves it to the detection position, the displacement sensor senses in real time whether the spring is deformed. When the displacement sensor senses that the spring is deformed, it determines that the sample bottle grasped by the suction cup has touched a foreign object. At this time, the microcontroller immediately sends an instruction to the three-axis motor, and the three-axis motor stops driving the motion rod to avoid the sample bottle from being broken, and executes step S7 to end the sampling task.

7. The sample grabbing method according to claim 1, characterized in that: When the displacement sensor senses that the spring has deformed, in order to avoid misjudgment, the displacement sensor continues to detect for 200ms. During the continuous detection process, if the displacement sensor senses that the spring deformation continues to increase, it is determined that a touch has occurred.

8. The sample grabbing method according to claim 1, characterized in that: In step S3, when the sample bottles are stacked, if the displacement sensor senses spring deformation when |xa| is less than 10 mm, it is determined that the suction cup has touched the sample bottle. At this time, the single-chip microcomputer sends a command to the three-axis motor to stop driving the motion rod downward and controls the vacuum pump to start. After the suction cup grabs the upper sample bottle, step S4 is executed; If the displacement sensor does not sense the deformation of the spring when |xa| is less than 10mm, the three-axis motor continues to drive the motion rod downward; if the displacement sensor senses the deformation of the spring when |xah| is less than 10mm, it is determined that the suction cup has touched the sample bottle on the lower layer, and h is the height of the sample bottle; at this time, the microcontroller sends a command to the three-axis motor to stop driving the motion rod downward and control the vacuum pump to start, and the suction cup grabs the sample bottle on the lower layer and then executes step S4.

9. The sample grabbing method according to claim 8, characterized in that: In step S3, if the displacement sensor does not sense the deformation of the spring when xah≥10mm, the three-axis motor continues to drive the motion rod down until the displacement sensor senses the deformation of the spring. At this time, it is determined that there is no sample bottle below, causing the suction cup to touch the sample plate. At this time, the microcontroller immediately sends an instruction to the three-axis motor, and the three-axis motor stops driving the motion rod down to avoid damage to the suction cup caused by squeezing, and executes step S7 to end the sampling task.

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