Liquid scintillation spectrometer sample grabbing device and grabbing method

Abstract

The invention provides a liquid scintillation spectrometer sample grabbing device and method, the liquid scintillation spectrometer sample grabbing device at least comprises a motion rod and a suction cup installed at the bottom of the motion rod, the motion rod moves under the driving of a three-axis motor, and the suction cup adsorbs and fixes a sample bottle under the action of a vacuum pump; the top of the spring is fixedly connected with the moving rod; the bottom of the spring is fixedly connected with the sucker; two ends of the displacement sensor are fixedly connected with two ends of the spring, deformation of the spring is synchronously fed back to the displacement sensor, and the displacement sensor acquires deformation quantity of the spring through circuit conversion; the single-chip microcomputer is connected with the vacuum pump, the three-axis motor and the displacement sensor at the same time, spring deformation data collected by the displacement sensor is transmitted to the single-chip microcomputer, and the single-chip microcomputer controls starting and stopping of the vacuum pump and operation of the three-axis motor. The invention further provides a collision detection method and a method for reliably grabbing the sample in cooperation with a control technology, and therefore the situation that the sample bottle collides with foreign matter in the moving process and is damaged is avoided.

Description

Technical Field

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

[0002] In the nuclear radiation measurement industry, as a β-ray detection device, the liquid scintillation spectrometer has a wide range of applications. It plays an irreplaceable role in archaeology for determining the age of items, radioactive detection of nuclear wastewater, nuclear pollution detection of seafood, medical physical examinations, etc. The measurement time of the liquid scintillation spectrometer for samples is often long, and the samples to be measured generally need to queue for testing. After the samples to be measured are prepared, they need to be kept in the dark for a period of time for accurate measurement. Therefore, the automatic sample replacement function is almost a standard function of the liquid scintillation spectrometer. In order to improve the detection efficiency, the sample bottles mostly use glass containers. Glass containers are fragile. Since the samples are mostly radioactive substances in most cases, once the sample bottle breaks, it will cause great economic losses and safety problems. Therefore, it is required that the automatic sampling system is stable and reliable, and it also needs to be able to continuously process as many samples to be measured as possible.

[0003] Currently, the liquid scintillation spectrometer (hereinafter referred to as the liquid scintillator) can hold the largest number of samples in 430 positions of 20 mL sample bottles. There are currently two common sample injection methods for liquid scintillation equipment. One is bottom injection. The bottom injection means transporting the sample to the bottom of the measurement position and then pushing the sample to the measurement position with a moving rod. The other is top injection. The top injection means transporting the sample to the top of the measurement position and then sucking the sample with a moving rod and sending it to the measurement position. The method of using a moving rod to grasp the sample, as the name implies, means that a sampling device composed of a rod and a suction cup can be moved to any position within a three-dimensional space by a three-dimensional motion motor. The advantage of this method is that sampling can be performed at any position within the space without moving other samples and sample trays, which mostly improves the space utilization rate and is very easy to increase the number of samples. Moreover, it is also very easy to complete the temporary insertion of samples to be measured. However, the disadvantage of this method is also obvious. The sample being grasped has no protection during the movement process. If any mistake occurs during the grasping of the sample, it will cause the sample bottle to break.

[0004] The grasping control method of traditional liquid scintillation automatic sampling systems mostly adopts a fixed-position sampling method without feedback. The sample tray with samples is at a fixed position. When sampling, the moving rod moves a fixed step length to pick up the sample, and when injecting the sample, it moves a fixed step length to transport the sample to the measurement position. Obviously, this fixed-position sampling method has no ability to identify whether the moving rod reaches the sample position and eliminate errors, and there will always be abnormal stops during long-term operation. Moreover, since the measurement position needs to be surrounded by a detector, a plastic scintillator, a reflective layer, and a shielding layer, the space at the measurement position is often very narrow, just about the size of one sample vial. Any larger deviation or mistake during operation will cause the sample vials to collide, and if the collision is not controlled, the sample vials will break. The traditional liquid scintillation design has a design solution that uses a spring for buffering to eliminate errors during contact. This solution can only prevent collisions caused by single errors and often requires frequent zero-position corrections to ensure reliability, which undoubtedly increases unnecessary operating actions and introduces other operating risks.

[0005] In addition, in the existing technical reports on using a moving rod to grasp samples, there is no design for stacking samples, that is, two or more samples are placed in a sample tray in a stacked form. This placement method is the sample placement method with the highest space utilization rate, and its advantages are very obvious. The maximum number of samples can be placed within a fixed space. However, at present, the field cannot achieve grasping and injecting samples in a stacked manner. Summary of the Invention

[0006] This application provides a sample grasping device and a grasping method for a liquid scintillation spectrometer, which solve the deficiencies in the prior art. In this application, a grasping device is jointly composed of a moving rod + a spring + a displacement sensor + an air suction system, adding a collision detection structure design, and providing a collision detection method and the process of how to cooperate with control technology to achieve reliable sample grasping, thereby avoiding damage to the sample vial when it hits foreign objects during the movement of the sample vial.

[0007] The technical solutions adopted to achieve the above objects of the present invention are as follows: A sample grasping device for a liquid scintillation spectrometer includes at least a moving rod and a suction cup installed 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 vial under the action of a vacuum pump. It further includes: A spring, the top of the spring is fixedly connected to the moving rod, and the bottom of the spring is fixedly connected to the suction cup; A displacement sensor, both ends of the displacement sensor are fixedly connected to both ends of the spring. The deformation of the spring is synchronously fed back to the displacement sensor, and the displacement sensor collects the deformation amount of the spring through circuit conversion; The single-chip microcomputer is connected to a vacuum pump, a three-axis motor, and a displacement sensor at the same time. The data of the spring deformation 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.

[0008] Further, the moving rod is a hollow metal tube, and an air pipe is arranged between the vacuum pump and the suction cup. The air pipe passes through the inside of the metal tube and the inside of the spring.

[0009] Further, the displacement sensor is connected to the ground in series with a voltage-dividing resistor. The displacement sensor is synchronously compressed and deformed with the spring. In the compressed state, the resistance value of the displacement sensor itself becomes smaller, and thus the voltage at both ends becomes smaller. The displacement sensor is connected to the ADC interface built in the single-chip microcomputer and transmits the voltage signal to the single-chip microcomputer.

[0010] Further, a USART serial port is set in the single-chip microcomputer. The single-chip microcomputer is connected to the three-axis motor through the USART serial port and sends instructions; an IO interface is also set in the single-chip microcomputer. The single-chip microcomputer controls the on-off of the MOS transistor to drive the electromagnetic relay through the IO interface to realize the opening and closing of the vacuum pump.

[0011] In this application, a sample grasping method based on the above-mentioned sample grasping device of the liquid scintillation spectrometer is also provided, including the following steps: S1 The single-chip microcomputer receives the sample injection instruction and sends an instruction to the three-axis motor through the serial port of the single-chip microcomputer. The three-axis motor drives the moving rod to move to directly above the sample bottle to be taken. S2 The single-chip microcomputer sends an instruction to the three-axis motor, and the three-axis motor drives the moving rod to descend. The touch determination step length a set in advance is stored in the single-chip microcomputer. 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, the single-chip microcomputer retrieves the real-time descent step length x of the moving rod. If the displacement sensor does not sense the deformation of the spring when a - x ≥ 10 mm, the three-axis motor continues to drive the moving rod to descend, and step S3 is executed; if the displacement sensor senses the deformation of the spring when a - x ≥ 10 mm, it is determined that a foreign object has been hit. At this time, the single-chip microcomputer immediately sends an instruction to the three-axis motor, and the three-axis motor stops driving the moving rod to descend to avoid damage caused by extrusion, and step S7 is executed to end the sample injection task. The S3 three-axis motor continuously drives the moving rod to descend. If the displacement sensor senses that the spring is deformed when |x - a| < 10 mm, it is determined that the suction cup has touched the sample bottle. At this time, the single-chip microcomputer issues an instruction to the three-axis motor to stop driving the moving 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 that the spring is deformed when |x - a| < 10 mm, the three-axis motor continuously drives the moving rod to descend until the displacement sensor senses that the spring is deformed. At this time, it is determined that there is no sample bottle below, resulting in the suction cup touching the sample tray. At this time, the single-chip microcomputer immediately issues an instruction to the three-axis motor, and the three-axis motor stops driving the moving rod to descend to avoid damage to the suction cup caused by extrusion, and step S7 is executed to end the sample injection task; After the suction cup in S4 grabs the sample bottle, the single-chip microcomputer sends an instruction to the three-axis motor. Driven by the three-axis motor, the moving rod grabs the sample bottle and first rises and then moves to the detection position; In S5, the single-chip microcomputer sends an instruction to the three-axis motor. The three-axis motor drives the moving rod to descend. During the descent, the displacement sensor continuously senses whether the spring is deformed. When the displacement sensor senses that the spring is deformed, it is determined that the bottom of the sample bottle has touched the bottom surface of the detection position. At this time, the single-chip microcomputer immediately issues an instruction to the three-axis motor, and the three-axis motor stops driving the moving rod to descend to avoid damage caused by extrusion. Then the single-chip microcomputer controls the vacuum pump to close, and the suction cup releases the grip on the sample bottle, and the sample bottle remains at the detection position; After the suction cup releases the grip in S6, the single-chip microcomputer sends an instruction to the three-axis motor. Driven by the three-axis motor, the moving rod first rises and then moves to directly above the next sample bottle to be taken; Loop through steps S2 - S6 until all sample bottles have been injected, and end the sample injection task.

[0012] Further, 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, control the moving rod to continue descending by 2 mm. If the displacement sensor senses that the spring further contracts, it is determined that the suction cup is in good contact with the sample bottle or the sample bottle has touched the bottom well.

[0013] Further, in step S4, during the process of the moving rod grabbing the sample bottle and moving it to the detection position, the displacement sensor continuously senses whether the spring is deformed. When the displacement sensor senses that the spring is deformed, it is determined that the sample bottle grabbed by the suction cup has touched a foreign object. At this time, the single-chip microcomputer immediately issues an instruction to the three-axis motor, and the three-axis motor stops driving the moving rod to move to avoid the sample bottle being broken, and step S7 is executed to end the sample injection task.

[0014] Further, when the displacement sensor senses that the spring is deformed, to avoid misjudgment, the displacement sensor continuously detects for 200 ms. If the spring deformation amount is sensed to continue to increase during the continuous detection, it is determined that a touch has occurred.

[0015] Further, in step S3, when the sample bottles are stacked, if the displacement sensor senses that the spring is deformed when |x - a| < 10 mm, it is determined that the suction cup touches the sample bottle. At this time, the single-chip microcomputer issues an instruction to the three-axis motor to stop driving the moving rod to descend and controls the vacuum pump to start. After the suction cup grabs the upper-layer sample bottle, step S4 is executed; If the displacement sensor does not sense that the spring is deformed when |x - a| < 10 mm, the three-axis motor continues to drive the moving rod to descend; when the displacement sensor senses that the spring is deformed when |x - a - h| < 10 mm, it is determined that the suction cup touches the lower-layer sample bottle, where h is the height of the sample bottle; at this time, the single-chip microcomputer issues an instruction to the three-axis motor to stop driving the moving rod to descend and controls the vacuum pump to start. After the suction cup grabs the lower-layer sample bottle, step S4 is executed.

[0016] Further, in step S3, if the displacement sensor does not sense that the spring is deformed when x - a - h ≥ 10 mm, the three-axis motor continues to drive the moving rod to descend until the displacement sensor senses that the spring is deformed. At this time, it is determined that there is no sample bottle below, resulting in the suction cup touching the sample tray. At this time, the single-chip microcomputer immediately issues an instruction to the three-axis motor, and the three-axis motor stops driving the moving rod to descend to avoid damaging the suction cup due to extrusion, and step S7 is executed to end the sample injection task.

[0017] 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 the design of a displacement sensor to the liquid scintillation sample injection system. When the relative position within the sensor range of the displacement sensor changes, the resistance of the sensor will change accordingly, and the change in position can be reflected through the change in resistance value. In the present application, the displacement sensor is fixed at both ends of the spring, so that the change of the displacement sensor can reflect the deformation of the spring. The change of the displacement sensor can be sent to the single-chip microcomputer through circuit conversion to form a closed-loop control. When 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 feeds back the spring contraction information to the single-chip microcomputer, and the single-chip microcomputer can judge that the moving rod just touches the sample bottle, so as to ensure that the sample is correctly grabbed.

[0018] 2. The present application can avoid the sample bottle being damaged by hitting foreign objects during the movement process. When the moving rod grabs the sample bottle, if the sample bottle hits something, the spring at the contact end of the moving rod will contract, and the displacement sensor feeds back the spring contraction information to the single-chip microcomputer. The single-chip microcomputer can judge that the sample bottle touches a foreign object, realizing the collision detection of the sample bottle, and timely stopping the movement can avoid the sample bottle being broken. The foreign object may be the edge of the sample tray, the edge of the sample injection port, or a sample repeatedly placed in the same position. Therefore, the present application also has the functions of detecting and preventing multiple samples from being placed in the measurement position, detecting whether there is a sample in the sample tray, and avoiding overloading the sample tray with samples.

[0019] 3. The present application also supports a grasping method for stacking sample bottles. Since collision detection is provided in the present application, the sample bottles can be detected at any height through collision detection, thereby realizing sampling in a stacked manner. During specific sampling, the bottom sample bottle will trigger collision detection due to the blockage at the bottom of the sample tray, and the upper sample bottle will trigger collision detection due to the blockage of the lower sample bottle, thereby triggering the single-chip microcomputer to control whether to place the sample and whether to sample. The single-chip microcomputer can record the movement step length of the moving rod as an auxiliary, and can determine which layer of the sample bottle is currently touched based on the fixed height of the sample bottle. Therefore, the grasping device and method provided in the present application support stacking placement, thereby further achieving the purpose of higher space utilization rate and more sample bottles. Description of the Drawings

[0020] Figure 1 is a schematic structural diagram of the liquid scintillation spectrometer sample grasping device provided by the present application; Figure 2 is a module component diagram of the liquid scintillation spectrometer sample grasping device provided by the present application; Figure 3 is a circuit diagram of the liquid scintillation spectrometer sample grasping device provided by the present application; Figure 4 is an overall flowchart of the sample grasping method provided by the present application; Figure 5 is a collision detection flowchart in the sample grasping method provided by the present application; Figure 6 is a schematic diagram of the stacked state of the sample bottles in Example 2.

[0021] In the figure: 1 - moving rod, 2 - suction cup, 3 - spring, 4 - displacement sensor, 5 - sample bottle, 6 - sample tray. Detailed Embodiments

[0022] The following will describe the present application in detail with reference to the accompanying drawings and specific embodiments.

[0023] The mechanical structure of the liquid scintillation spectrometer sample grasping device provided in this embodiment is as Figure 1As shown in the figure, it includes the following components: a moving rod 1 and a suction cup 2 installed at the bottom of the moving rod 1. The suction cup 2 adsorbs and fixes the sample bottle 5 under the action of a vacuum pump. The moving rod 1 moves under the drive of a three-axis motor. The top of the spring 3 is fixedly connected to the moving rod 1, and the bottom of the spring 3 is fixedly connected to the suction cup 2. The moving rod 1 is a hollow metal tube. An air pipe is arranged between the vacuum pump and the suction cup 2, and the air pipe passes through the inside of the metal tube and the inside of the spring 3. Both ends of the displacement sensor 4 are fixedly connected to both ends of the spring 3. The deformation of the spring 3 is synchronously fed back to the displacement sensor 4, and the displacement sensor 4 collects the deformation amount of the spring 3 through circuit conversion.

[0024] The module settings of the single-chip microcomputer are as Figure 2 shown. The single-chip microcomputer is simultaneously connected to the vacuum pump, the three-axis motor, and the displacement sensor. Its circuit diagram is as Figure 3 shown. The spring deformation amount data collected by the displacement sensor is transmitted to the single-chip microcomputer. The single-chip microcomputer controls the opening and closing of the vacuum pump and the operation of the three-axis motor. The displacement sensor is connected in series with a voltage-dividing resistor to the ground. The displacement sensor and the spring are compressed and deformed synchronously. In the compressed state, the resistance value of the displacement sensor itself becomes smaller, and thus the voltage at both ends becomes smaller. The displacement sensor is connected to the built-in ADC interface of the single-chip microcomputer and transmits the voltage signal to the single-chip microcomputer. The single-chip microcomputer is provided with a USART serial port. The single-chip microcomputer is connected to the three-axis motor through the USART serial port and sends instructions. The single-chip microcomputer is also provided with an IO interface. The single-chip microcomputer controls the on and off of the MOS tube to drive the electromagnetic relay through the IO interface to realize the opening and closing of the vacuum pump.

[0025] Embodiment 1 In this embodiment, a single-layer sample bottle is taken as an example to illustrate in detail the method for grasping samples of the liquid scintillation spectrometer provided. Refer to Figure 4 shown. This embodiment includes the following steps: S1 The single-chip microcomputer receives the sample injection instruction and sends an instruction to the three-axis motor through the serial port of the single-chip microcomputer. The three-axis motor drives the moving rod to move to directly above the sample bottle to be taken. S2 The single-chip microcomputer sends an instruction to the three-axis motor. The three-axis motor drives the moving rod to descend. The single-chip microcomputer stores a pre-set touch determination step length a in advance. The value of the touch determination step length a corresponds to the distance from the suction cup to the top of the sample bottle. Therefore, theoretically, by controlling the descending step length a of the moving rod, it can basically move to near the sample bottle (considering there are errors).

[0026] During the descending process, the single-chip microcomputer retrieves the real-time descending step length x of the moving rod. If the displacement sensor does not sense the deformation of the spring when a - x ≥ 10 mm, the three-axis motor continuously drives the moving rod to descend and executes step S3. If the displacement sensor senses that the spring is deformed when a - x ≥ 10 mm, it is determined that a foreign object has been hit. At this time, the single-chip microcomputer immediately sends an instruction to the three-axis motor, and the three-axis motor stops driving the moving rod to descend to avoid damage caused by extrusion, and step S7 is executed to end the sample injection task; at this time, the staff needs to open the sample injection device of the liquid scintillation spectrometer, find out the cause of the abnormal collision and solve it, and then start the sample grabbing and injection again after zeroing.

[0027] S3 The three-axis motor continuously drives the moving rod to descend. If the displacement sensor senses that the spring is deformed when |x - a| < 10 mm, it is determined that the suction cup touches the sample bottle. At this time, control the moving rod to continue to descend by 2 mm. If the displacement sensor senses that the spring further contracts, it is determined that the suction cup is in good contact with the sample bottle. At this time, the single-chip microcomputer sends an instruction to the three-axis motor to stop driving the moving 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 that the spring is deformed when |x - a| < 10 mm, the three-axis motor continuously drives the moving rod to descend until the displacement sensor senses that the spring is deformed. At this time, it is determined that there is no sample bottle below, resulting in the suction cup touching the sample tray. At this time, the single-chip microcomputer immediately sends an instruction to the three-axis motor, and the three-axis motor stops driving the moving rod to descend to avoid damage to the suction cup caused by extrusion, and step S7 is executed to end the sample injection task; this step indicates that all sample injections have been completed, and all sample bottles on the sample tray have been injected.

[0028] S4 After the suction cup grabs the sample bottle, the single-chip microcomputer sends an instruction to the three-axis motor. Driven by the three-axis motor, the moving rod grabs the sample bottle and first rises and then moves to the detection position; during this process, the displacement sensor continuously senses whether the spring is deformed. When the displacement sensor senses that the spring is deformed, it is determined that the sample bottle grabbed by the suction cup touches a foreign object. At this time, the single-chip microcomputer immediately sends an instruction to the three-axis motor, and the three-axis motor stops driving the moving rod to move to avoid the sample bottle being broken, and step S7 is executed to end the sample injection task. At this time, the staff needs to open the sample injection device of the liquid scintillation spectrometer, find out the cause of the abnormal collision and solve it, and then start the sample grabbing and injection again after zeroing.

[0029] S5 The single-chip microcomputer sends an instruction to the three-axis motor, and the three-axis motor drives the moving rod to descend. During the descent, the displacement sensor continuously senses whether the spring is deformed. When the displacement sensor senses that the spring is deformed, it is determined that the bottom of the sample bottle touches the bottom surface of the detection position. At this time, control the moving rod to continue to descend by 2 mm. If the displacement sensor senses that the spring further contracts, it is determined that the sample bottle touches the bottom well. At this time, the single-chip microcomputer immediately sends an instruction to the three-axis motor, and the three-axis motor stops driving the moving rod to descend to avoid damage caused by extrusion. Then the single-chip microcomputer controls the vacuum pump to close, and the suction cup releases the grab on the sample bottle, and the sample bottle remains at the detection position; After the S6 suction cup releases the grasp, the single-chip microcomputer sends an instruction to the three-axis motor. Driven by the three-axis motor, the moving rod first rises and then moves to directly above the next sample bottle to be picked up; S7 Loop through steps S2 - S6 until all sample bottles have been sampled, and end the sampling task.

[0030] In the above steps, when a collision is detected, that is, when the displacement sensor senses that the spring deforms, in order to avoid misjudgment, collision detection needs to be performed. The collision detection process is as Figure 5 shown. Since the displacement sensor is fixed at both ends of the spring, when not in contact with an object, the spring will not be compressed and the value of the displacement sensor will not change. When in contact with an object, the spring is compressed and the value of the displacement sensor will decrease accordingly. When the value of the displacement sensor is detected to decrease, in order to prevent misjudgment, it will be continuously detected for 200 ms to ensure reliability. During the continuous detection process, if it is sensed that the value of the displacement sensor continues to decrease (that is, it means the deformation of the spring continues to increase), it is determined that a touch has occurred. In this way, the situation of misjudgment caused by random drift or accidental jump of the sensor is avoided.

[0031] Embodiment 2 In this embodiment, taking the double-layer stacking of sample bottles as an example, the provided method for grasping samples of a liquid scintillation spectrometer will be described in detail. The state of the double-layer stacking of sample bottles is referred to Figure 6 as shown. The specific steps in this embodiment are basically the same as those in Embodiment 1. The difference lies in step S3: In step S3, when the sample bottles are stacked in a double-layer manner, if the displacement sensor senses that the spring deforms when |x - a| < 10 mm, it is determined that the suction cup has touched the upper sample bottle. At this time, the single-chip microcomputer sends an instruction to the three-axis motor to stop driving the moving rod to descend and controls the vacuum pump to start. After the suction cup grasps the upper sample bottle, step S4 is executed; If the displacement sensor does not sense that the spring deforms when |x - a| < 10 mm, the three-axis motor continues to drive the moving rod to descend; when the displacement sensor senses that the spring deforms when |x - a - h| < 10 mm, it is determined that the suction cup has touched the lower sample bottle, where h is the height of the sample bottle, which is taken as 30 mm in this embodiment; at this time, the single-chip microcomputer sends an instruction to the three-axis motor to stop driving the moving rod to descend and controls the vacuum pump to start. After the suction cup grasps the lower sample bottle, step S4 is executed.

[0032] If the displacement sensor does not detect the deformation of the spring when x - a - h ≥ 10 mm, the three-axis motor continuously drives the moving rod to descend until the displacement sensor detects the deformation of the spring. At this time, it is determined that there is no sample vial below, resulting in the suction cup touching the sample tray. At this time, the single-chip microcomputer immediately sends an instruction to the three-axis motor, and the three-axis motor stops driving the moving rod to descend to avoid damage to the suction cup caused by extrusion, and then executes step S7 to end the sample injection task. This step indicates that all sample injections have been completed, and all the sample vials on the sample tray have been injected.

[0033] Embodiment 3 The present application also supports stacking three or more sample vials. Taking the stacking of three sample vials as an example, the method for grasping samples of the provided liquid scintillation spectrometer will be described in detail. The specific steps in this embodiment are basically the same as those in Embodiment 1, and the difference lies in step S3: In step S3, when the sample vials are stacked in a double-layer manner, if the displacement sensor detects the deformation of the spring when |x - a| < 10 mm, it is determined that the suction cup touches the upper sample vial. At this time, the single-chip microcomputer sends an instruction to the three-axis motor to stop driving the moving rod to descend and controls the vacuum pump to start. After the suction cup grasps the upper sample vial, step S4 is executed; If the displacement sensor does not detect the deformation of the spring when |x - a| < 10 mm, the three-axis motor continuously drives the moving rod to descend; when the displacement sensor detects the deformation of the spring when |x - a - h| < 10 mm, it is determined that the suction cup touches the middle sample vial, where h is the height of the sample vial, and in this embodiment, the value is 30 mm; at this time, the single-chip microcomputer sends an instruction to the three-axis motor to stop driving the moving rod to descend and controls the vacuum pump to start. After the suction cup grasps the lower sample vial, step S4 is executed.

[0034] If the displacement sensor does not detect the deformation of the spring when |x - a - h| < 10 mm, the three-axis motor continuously drives the moving rod to descend; when the displacement sensor detects the deformation of the spring when |x - a - 2h| < 10 mm, it is determined that the suction cup touches the lower sample vial; at this time, the single-chip microcomputer sends an instruction to the three-axis motor to stop driving the moving rod to descend and controls the vacuum pump to start. After the suction cup grasps the lower sample vial, step S4 is executed.

[0035] If the displacement sensor does not detect the deformation of the spring when x - a - 2h ≥ 10 mm, the three-axis motor continuously drives the moving rod to descend until the displacement sensor detects the deformation of the spring. At this time, it is determined that there is no sample vial below, resulting in the suction cup touching the sample tray. At this time, the single-chip microcomputer immediately sends an instruction to the three-axis motor, and the three-axis motor stops driving the moving rod to descend to avoid damage to the suction cup caused by extrusion, and then executes step S7 to end the sample injection task. This step indicates that all sample injections have been completed, and all the sample vials on the sample tray have been injected.

Claims

1. A sample grasping device for a liquid scintillation spectrometer, at least comprising 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, characterized in that It also includes: A spring, the top of the spring is fixedly connected to the moving rod, and the bottom of the spring is fixedly connected to the suction cup; A displacement sensor, both ends of the displacement sensor are fixedly connected to both ends of the spring, the deformation of the spring is synchronously fed back to the displacement sensor, and the displacement sensor collects the deformation amount of the spring through circuit conversion; A single-chip microcomputer, which is connected to the vacuum pump, the three-axis motor and the displacement sensor at the same time. The spring deformation amount 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.

2. The liquid scintillation spectrometer sample grasping device according to claim 1, wherein: The moving rod is a hollow metal tube, and an air pipe is arranged between the vacuum pump and the suction cup, and the air pipe passes through the inside of the metal tube and the inside of the spring.

3. The liquid scintillation spectrometer sample grasping device according to claim 1, wherein: The displacement sensor is connected to the ground in series with a voltage-dividing resistor. The displacement sensor is compressed and deformed synchronously with the spring. In the compressed state, the resistance value of the displacement sensor itself becomes smaller, and thus the voltage at both ends becomes smaller. The displacement sensor is connected to the ADC interface built in the single-chip microcomputer and transmits the voltage signal to the single-chip microcomputer.

4. The liquid scintillation spectrometer sample grasping device according to claim 1, wherein: The single-chip microcomputer is provided with a USART serial port, and the single-chip microcomputer is connected to the three-axis motor through the USART serial port and sends instructions; the single-chip microcomputer is also provided with an IO interface, and 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 grasping method of the liquid scintillation spectrometer sample grasping device according to claim 1, characterized in that It includes the following steps: S1 The single-chip microcomputer receives the sample injection instruction, sends an instruction to the three-axis motor through the serial port of the single-chip microcomputer, and the three-axis motor drives the moving rod to move to directly above the sample bottle to be taken; S2 The single-chip microcomputer sends an instruction to the three-axis motor, and the three-axis motor drives the moving rod to descend. The single-chip microcomputer stores the pre-set touch determination step length a in advance, 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, the single-chip microcomputer retrieves the real-time descent step length x of the moving rod. If the displacement sensor does not sense the deformation of the spring when a - x ≥ 10 mm, the three-axis motor continues to drive the moving rod to descend, and step S3 is executed; if the displacement sensor senses the deformation of the spring when a - x ≥ 10 mm, it is determined that a foreign object has been hit. At this time, the single-chip microcomputer immediately sends an instruction to the three-axis motor, and the three-axis motor stops driving the moving rod to descend to avoid damage caused by extrusion, and step S7 is executed to end the sample injection task; S3 The three-axis motor continues to drive the moving rod to descend. If the displacement sensor senses the deformation of the spring when |x - a| < 10 mm, it is determined that the suction cup touches the sample bottle. At this time, the single-chip microcomputer sends an instruction to the three-axis motor to stop driving the moving 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 the deformation of the spring when |x - a| < 10 mm, the three-axis motor continues to drive the moving rod to descend until the displacement sensor senses the deformation of the spring. At this time, it is determined that there is no sample bottle below, resulting in the suction cup touching the sample tray. At this time, the single-chip microcomputer immediately sends an instruction to the three-axis motor, and the three-axis motor stops driving the moving rod to descend to avoid damage to the suction cup caused by extrusion, and step S7 is executed to end the sample injection task; S4 After the suction cup grabs the sample bottle, the single-chip microcomputer sends an instruction to the three-axis motor. Driven by the three-axis motor, the moving rod grabs the sample bottle and first rises and then moves to the detection position; The S5 single-chip microcomputer sends an instruction to the three-axis motor, and the three-axis motor drives the moving rod to descend. During the descent, the displacement sensor continuously senses whether the spring deforms. When the displacement sensor senses that the spring deforms, it is determined that the bottom of the sample bottle touches the bottom surface of the detection position. At this time, the single-chip microcomputer immediately sends an instruction to the three-axis motor, and the three-axis motor stops driving the moving rod to descend to avoid damage caused by extrusion. Then the single-chip microcomputer controls the vacuum pump to close, and the suction cup releases the grasping of the sample bottle, and the sample bottle remains at the detection position; After the suction cup releases the grasping in S6, the single-chip microcomputer sends an instruction to the three-axis motor. Driven by the three-axis motor, the moving rod first rises and then moves to directly above the next sample bottle to be picked up; Loop steps S2 - S6 until the injection of all sample bottles is completed and the injection task ends.

6. The sample grabbing method according to claim 5, wherein: 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, control the moving rod to continue descending by 2 mm. If the displacement sensor senses that the spring further contracts, it is determined that the suction cup is in good contact with the sample bottle or the sample bottle touches the bottom well.

7. The sample grasping method according to claim 5, wherein: In step S4, during the process of the moving rod grasping the sample bottle and moving it to the detection position, the displacement sensor continuously senses whether the spring deforms. When the displacement sensor senses that the spring deforms, it is determined that the sample bottle grasped by the suction cup touches a foreign object. At this time, the single-chip microcomputer immediately sends an instruction to the three-axis motor, and the three-axis motor stops driving the moving rod to move to avoid the sample bottle being broken, and step S7 is executed to end the injection task.

8. The sample grasping method according to claim 5, wherein: When the displacement sensor senses that the spring deforms, to avoid misjudgment, the displacement sensor continuously detects for 200 ms. If it senses that the deformation amount of the spring continues to increase during the continuous detection process, it is determined that a touch has occurred.

9. The sample grasping method according to claim 5, characterized in that: In step S3, when the sample bottles are stacked, if the displacement sensor senses that the spring deforms when |x - a| < 10 mm, it is determined that the suction cup touches the sample bottle. At this time, the single-chip microcomputer sends an instruction to the three-axis motor to stop driving the moving rod to descend and controls the vacuum pump to turn on. After the suction cup grasps the upper-layer sample bottle, step S4 is executed; If the displacement sensor does not sense that the spring deforms when |x - a| < 10 mm, the three-axis motor continuously drives the moving rod to descend; when the displacement sensor senses that the spring deforms when |x - a - h| < 10 mm, it is determined that the suction cup touches the lower-layer sample bottle, where h is the height of the sample bottle; at this time, the single-chip microcomputer sends an instruction to the three-axis motor to stop driving the moving rod to descend and controls the vacuum pump to turn on. After the suction cup grasps the lower-layer sample bottle, step S4 is executed.

10. The sample grabbing method according to claim 9, characterized in that: In step S3, if the displacement sensor does not sense that the spring deforms when x - a - h ≥ 10 mm, the three-axis motor continuously drives the moving rod to descend until the displacement sensor senses that the spring deforms. At this time, it is determined that there is no sample bottle below, resulting in the suction cup touching the sample tray. At this time, the single-chip microcomputer immediately sends an instruction to the three-axis motor, and the three-axis motor stops driving the moving rod to descend to avoid damage to the suction cup caused by extrusion, and step S7 is executed to end the injection task.

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