CN113057619A - Method for controlling movement of sickbed - Google Patents
Method for controlling movement of sickbed Download PDFInfo
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Abstract
The invention provides a method for controlling the movement of a sickbed, which is used for nuclear magnetic resonance imaging equipment to perform nuclear magnetic resonance imaging, wherein the nuclear magnetic resonance imaging equipment comprises a bedplate, a servo driving system for driving the bedplate to move and a scanning imaging unit for imaging, a scanning aperture is formed in the scanning imaging unit, and the method for controlling the movement of the sickbed comprises the following steps: the servo driving system drives the bed plate to move so as to convey a patient into the scanning aperture; powering off the servo driving system; the scanning imaging unit performs magnetic resonance imaging on a patient. According to the method for controlling the movement of the sickbed, the servo driving system is powered off when nuclear magnetic resonance imaging scanning is carried out, and the servo driving system without power supply cannot generate electromagnetic interference on a scanning imaging unit of nuclear magnetic resonance imaging equipment, so that the imaging effect is improved, and the accuracy of clinical diagnosis is improved.
Description
Technical Field
The invention relates to the technical field of medical instruments, in particular to a method for controlling the movement of a sickbed.
Background
With the rapid development of medical technology, the medical nuclear magnetic resonance imaging technology has been widely applied to clinical examination of patients, and the nuclear magnetic resonance imaging can clearly distinguish the structures of soft tissues such as muscles, tendons, fat and the like, so that the diagnosis rate and accuracy of diseases are improved. The principle of the medical nuclear magnetic resonance imaging technology is as follows: the nuclear magnetic resonance imaging method includes exciting the atomic nucleus of hydrogen as main element of the patient in magnetic field with RF pulse to obtain nuclear magnetic resonance emitting signal, spatial encoding in gradient magnetic field, and reconstructing some section image of the patient with computer algorithm. The image obtained by the existing nuclear magnetic resonance scanning equipment always has artifacts, and the quality of the image is not high, so that the accuracy of clinical diagnosis is reduced.
Disclosure of Invention
The invention aims to provide a method for controlling the movement of a sickbed, which can improve the image quality and the accuracy of clinical diagnosis.
In order to achieve the above object, the present invention provides a method for controlling a motion of a patient bed, which is used for a magnetic resonance imaging apparatus to perform magnetic resonance imaging, the magnetic resonance imaging apparatus includes a patient bed, a servo driving system for driving the patient bed to move, and a scanning imaging unit for imaging, the scanning imaging unit is formed with a scanning aperture, and the method for controlling a motion of a patient bed includes:
the servo driving system drives the bed plate to move so as to convey a patient into the scanning aperture;
powering off the servo driving system;
the scanning imaging unit performs magnetic resonance imaging on a patient.
Optionally, servo drive system includes first servo motor, first servo driver and first encoder, through first servo driver control first servo motor's direction of rotation and slew velocity, through first servo motor drive the bed board is at first direction reciprocating motion, through first encoder acquires the first position information of bed board.
Optionally, the mri apparatus further includes a control unit, connected to the first encoder, and the first position information is transmitted to the control unit by the first encoder.
Optionally, when the servo drive system is powered off, the first servo driver, the first servo motor and the first encoder are all powered off, the control unit stores the first position information acquired by the first encoder at the moment of power off, and when the servo drive system is powered back, the control unit returns the stored first position information to the first encoder.
Optionally, the magnetic resonance imaging apparatus further includes a power supply unit, and when the servo drive system is powered off, the first servo driver and the first servo motor are both powered off, the power supply unit supplies power to the first encoder, and the first encoder transmits the first position information to the control unit in real time.
Optionally, servo drive system still includes second servo motor, second servo driver and second encoder, through second servo driver control second servo motor's direction of rotation and slew velocity, through second servo motor drive the bed board is at the ascending round trip movement of second direction, through the second encoder acquires the second positional information of bed board.
Optionally, when the servo drive system is powered off, the first servo driver, the first servo motor, the second servo motor and the second servo driver are all powered off, the power supply unit supplies power to the first encoder and the second encoder, and the first encoder and the second encoder respectively transmit the first position information and the second position information to the control unit in real time.
Optionally, the second encoder is connected to the second servo driver, and the second position information obtained by the second encoder is transmitted to the control unit through the second servo driver.
Optionally, when the servo drive system is powered off, the first servo driver, the first servo motor, the second encoder, the second servo motor and the second servo driver are all powered off, the power supply unit supplies power to the first encoder, and the first encoder transmits the first position information to the control unit in real time.
Optionally, the magnetic resonance imaging apparatus further includes two speed reducers, the output ends of the first servo motor and the second servo motor of the servo drive system are respectively connected to the bed plate through one speed reducer, and the transmission ratio of the speed reducers is greater than or equal to 2.
The invention provides a method for controlling the movement of a sickbed, which is used for nuclear magnetic resonance imaging equipment to perform nuclear magnetic resonance imaging, wherein the nuclear magnetic resonance imaging equipment comprises a bedplate, a servo driving system for driving the bedplate to move and a scanning imaging unit for imaging, a scanning aperture is formed in the scanning imaging unit, and the method for controlling the movement of the sickbed comprises the following steps: the servo driving system drives the bed plate to move so as to convey a patient into the scanning aperture; powering off the servo driving system; the scanning imaging unit performs magnetic resonance imaging on a patient. According to the method for controlling the movement of the sickbed, the servo driving system is powered off when nuclear magnetic resonance imaging scanning is carried out, and the servo driving system without power supply cannot generate electromagnetic interference on a scanning imaging unit of nuclear magnetic resonance imaging equipment, so that the imaging effect is improved, and the accuracy of clinical diagnosis is improved.
Drawings
Fig. 1 is a schematic structural diagram of an mri scanner according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a servo driving system according to an embodiment of the present invention;
fig. 3 is a flowchart of a method of bed motion control in the present embodiment;
fig. 4 is a schematic diagram of a servo driving system according to a second embodiment of the present invention;
fig. 5 is a schematic diagram of a servo driving system according to a third embodiment of the present invention;
fig. 6 is a schematic diagram of a servo driving system according to a fourth embodiment of the present invention;
fig. 7 is a schematic diagram of a servo driving system according to a fifth embodiment of the present invention;
fig. 8 is a flowchart of a method for controlling movement of a patient bed according to a fifth embodiment of the present invention;
wherein the reference numbers are as follows:
100-bed board; 110-a servo motor; 111-a first servo motor; 112-a second servomotor;
200-scanning imaging unit.
Detailed Description
The following describes in more detail embodiments of the present invention with reference to the schematic drawings. The advantages and features of the present invention will become more apparent from the following description. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention.
Example one
The operating principle of a nuclear magnetic resonance scanning apparatus is to place a patient in an externally applied magnetic field. The hydrogen nuclei in the patient are excited with radio frequency pulses causing the hydrogen nuclei to resonate. After stopping the radio frequency pulse, the hydrogen nuclei emit electrical signals, which are recorded by an in vitro receptor. Different substances have different relaxation signals under different magnetic field strengths and different proton density values, so that images of the organ tissues inside the patient can be generated.
Fig. 1 is a schematic structural diagram of a nuclear magnetic resonance scanning apparatus in an embodiment. As shown in fig. 1, the magnetic resonance imaging apparatus includes a scanning imaging unit 200 and a couch 100. The scanning imaging unit 200 is formed with a scanning aperture within which a patient is positioned when the scanning imaging unit 200 is imaging.
The scanning imaging unit 200 includes a main magnet unit, a gradient magnetic field unit and a radio frequency unit. The main magnet is used to generate a highly uniform and stable static magnetic field. So that the hydrogen nuclei in the body of the patient, which are in the magnetic field, are magnetized to form a magnetization vector. The gradient magnetic field unit comprises a gradient magnetic field generator and a gradient coil, wherein the gradient magnetic field generator is used for generating gradient current with a certain switch shape, and the gradient current is amplified and then sent to the gradient coil by a driving circuit to generate a required gradient magnetic field (the magnetic field of each point in space is regularly changed). The gradient magnetic field unit superposes a three-dimensional gradient magnetic field for the static magnetic field, so that each voxel in the effective volume has a spatial coordinate position. The three-dimensional gradient magnetic fields are generated by three gradient coils, respectively. In this way, the gradient magnetic field unit provides gradient magnetic fields in three directions of GX/GY and GZ so that spatial position information of MR signals (nuclear magnetic resonance signals) can be acquired. The radio frequency unit comprises a transmitting coil and a receiving coil. The transmit coil is used to establish a radio frequency magnetic field to effect radio frequency excitation. Causing hydrogen protons of the subject to enter a resonance state. The receive coils are used to detect MR signals. Echo signals generated by hydrogen protons during relaxation are received and processed.
The main magnet unit, the gradient magnetic field unit and the radio frequency unit in the scanning imaging unit 200 are physical components that are crucial for magnetic resonance imaging and image quality. In addition, the magnetic resonance scanning apparatus further includes a software program for image processing. The user uses these programs through the terminal of the operating system to perform image acquisition, image display and image analysis as required.
The scanning bed is used for carrying a patient and lifting and horizontally moving the patient into the scanning imaging unit 200. The scanning bed includes a bed frame and a bed board 100, the bed board 100 is movable along the bed frame in a horizontal direction to move a patient into or out of a scanning aperture of the scanning imaging unit 200, and a driving unit is provided in the bed frame for driving the bed board 100 to move horizontally. When the scanning imaging unit 200 scans a patient, a high requirement is imposed on the relative position of the patient and the scanning imaging unit 200. Therefore, the couch board 100 carrying the patient requires high positioning accuracy. In order to make the positioning accuracy of the bed board 100 meet the requirement. The driving unit generally adopts a servo driving system, and the table board 100 is precisely moved by a servo motor 110 and a corresponding servo driver in the servo driving system.
Fig. 2 is a schematic diagram of a servo driving system in the present embodiment. As shown in fig. 2, the servo driving system includes a servo motor 110, a servo driver and an encoder, the servo driver controls a rotation direction and a rotation speed of the servo motor, the servo motor drives the bed board 100 to move back and forth in a first direction, and the encoder obtains position information of the bed board 100.
Specifically, the servo motor 110 is a power source for controlling a mechanical element (in this embodiment, the mechanical element is the bed board 100) to operate in a servo driving system, and is an indirect speed change device of a supplementary motor. The servo motor 110 can make the speed and position precision of the controlled mechanical element very accurate, and can convert the voltage signal into steering and rotating speed to drive the controlled object. The rotor speed of the servo motor 110 is controlled by an input signal and can be quickly responded, and is used as an actuating element in an automatic control system. The servo motor 110 further has a brake device, and after the servo motor 110 is powered off, the brake device locks, so that the servo motor 110 is kept at a position before the power off.
The servo motor 110 is connected to the servo driver by a power line and is powered by the power line. The power line of the servo motor 110 is also called a power line, and the power line is a connecting line for transmitting electric energy between the servo driver and the servo motor 110, and is used for completing the transportation of the electric energy. The servo power line comprises two parts, one part is a connecting line between the servo driver and the power supply, and the other part is a connecting line between the servo driver and the servo motor 110. The power line is usually a line carrying strong electricity, typically 220V or 380V ac. Therefore, a strong magnetic field is present around the power line. The encoder is connected to the servo drive and transmits position information of the encoder to the control unit (MPTC) via said servo drive.
It should be noted that, because the servo motor 110 needs to be controlled for precise positioning, the torque of the servo motor 110 needs to be adjusted in real time when the servo motor 110 is controlled, and the changing torque causes the current of the servo motor 110 to follow the change. This results in a servo motor 110 that is more likely to generate a magnetic field during operation. In addition, magnetic field generation is also caused by the structural limitation of the mri apparatus, such as too long power line from the servo driver to the servo motor 110, unstable switching power supply, or the interference of voltage division caused by the power supply shared by the servo driver and other electrical appliances.
The servo driver is a device for processing and converting the output controlled quantity of the position, the direction, the state of the servo motor 110 and the like of the object, and the servo driver and the servo motor 110 form a servo driving system. In the servo driving system, the servo motor 110 is mainly positioned by pulses, and when the servo motor 110 receives 1 pulse, the servo motor 110 rotates by an angle corresponding to 1 pulse, thereby realizing the control of the rotation angle. Meanwhile, the servo driver can convert the received pulse signal into position information or a velocity value of the output shaft of the servo motor 110 and output it to the main control system. The resulting servo drive generates a magnetic field when energized, due to the need for the servo drive to generate a pulse. However, since the servo driver is disposed in the power distribution cabinet at a far position of the scanning imaging unit 200, the magnetic field generated by the servo driver has less interference to the magnetic resonance imaging apparatus.
The encoder is generally disposed at a rear end of the servo motor 110 and is connected to a rotation shaft of the servo motor 110. An encoder is a device that compiles, converts, and formats signals (e.g., bitstreams) or data into a form of signals that can be communicated, transmitted, and stored. Encoders convert angular or linear displacements, called codewheels, into electrical signals, called coderulers. The encoder can be divided into a contact type and a non-contact type according to a reading mode; encoders can be classified into an incremental type and an absolute type according to their operation principles. Incremental encoders convert displacement into a periodic electrical signal, which is converted into a count pulse and position information. When the servo motor 110 works, the encoder sends out a corresponding number of pulses to the servo driving system, and the number of the pulses represents the displacement of the object driven by the servo motor 110, in this embodiment, the object driven by the servo motor 110 is the bed board 100. Thereby, the position or orientation of the table board 100, that is, the position information of the table board 100, can be acquired by the encoder.
If the servo motor 110 is close to the mri apparatus, the servo motor 110 may interfere with the uniformity of the static magnetic field generated by the main magnet in the scanning imaging unit 200, and on the other hand, the servo motor 110 may generate electromagnetic interference, interfere with the linear characteristics of the rf signal and the gradient magnetic field of the mri system, and may also affect the MR signal detected by the receiving coil, so that the mri is set in the scanning and image processing processes, and the obtained image has artifacts, which may cause the image quality to be degraded.
The servo motor 110 is disposed on the top board 100 far away from the magnetic resonance imaging device, that is, the servo motor 110 is disposed at the far end of the top board 100, and the magnetic force range of the magnetic resonance imaging device is usually about 2.5 meters, so the distance between the servo motor 110 and the top board 100 is at least 2.5 meters or more, so as to minimize the influence of the servo motor 110 on the scanning imaging unit 200. However, even so, the magnetic field generated when the servo motor 110 is energized still affects the magnetic field in the scanning imaging unit 200.
Based on this, the invention provides a method for controlling the movement of a hospital bed, which is used for nuclear magnetic resonance imaging equipment to perform nuclear magnetic resonance imaging, the nuclear magnetic resonance imaging equipment comprises a bed board 100, a servo driving system for driving the bed board 100 to move and a scanning imaging unit 200 for imaging, and the scanning imaging unit 200 is formed with a scanning aperture.
Fig. 3 is a flowchart of a method of controlling the movement of the patient bed in the present embodiment. As shown in fig. 3, the method for controlling the movement of the patient bed comprises the following steps:
step S101: the servo drive system drives the bed plate 100 to move to deliver the patient into the scanning aperture;
step S102: powering off the servo driving system;
step S103: the scan imaging unit 200 performs magnetic resonance imaging on a patient.
In the method for controlling the movement of the patient bed of the present invention, the table 100 is located at a predetermined position outside the scanning aperture of the scanning imaging unit 200. The patient lies on bed board 100 flatly to put the position to the patient, bed board 100 conveys the patient level to the scanning position in the scanning aperture of scanning imaging unit 200 after, cuts off the power supply to servo drive system, and during servo drive system cuts off the power supply, because servo motor 110's brake equipment locks, makes bed board 100 can not take place to remove. And after the nuclear magnetic resonance imaging scanning is carried out on the patient, the servo driving system is powered on again. The servo drive system drives the couch 100 to deliver the patient to a set position outside the scanning aperture of the scanning imaging unit 200. When the magnetic resonance imaging device scans a patient, the servo motor 110 without power supply can not generate electromagnetic induction, so that the servo motor 110 can not generate electromagnetic interference on the magnet in the scanning imaging unit 200. Thereby improving the imaging effect and improving the accuracy of clinical diagnosis.
Further, the magnetic resonance imaging apparatus further includes a control unit (MPTC), the encoder is connected to the servo driver, the servo driver is connected to the control unit (MPTC), and the encoder transmits the position information of the bed board 100 to the control unit (MPTC) through the servo driver.
Further, when the servo drive system is powered off, the servo driver, the servo motor 110 and the encoder are all powered off, the control unit (MPTC) stores the position information of the bed board 100 acquired by the encoder at the moment of power off, and when the servo drive system is powered back, the control unit (MPTC) returns the stored position information to the encoder through the servo driver.
It should be noted that the control unit (MPTC) also comprises a memory, which can store data from the master control system (host computer) and the servo drive, and can also be used to store the position information of the encoder delivering said control unit (MPTC).
Optionally, the encoder is an absolute encoder.
It is known that the encoder type is distinguished from the incremental encoder, in which the code disc has a fixed number of light gratings on the same circumference, and a certain number of pulses are generated by cutting light through the light gratings (the number of light gratings on each ring is the so-called resolution of the encoder), while the absolute encoder has a different number of light gratings at different circumferences and different intervals on the same code disc, i.e. when the code disc stops at a certain position, a fixed position can be combined by whether light is transmitted on each circumference of the code disc, and a fixed number is displayed after passing through an output line. The incremental encoder cannot read current position information and only can record the position information of a measured object by matching with a counter (such as a zero sensor). Therefore, the incremental encoder needs to be reset after power down. Compared with an incremental encoder, the absolute encoder can record position information, and the problem of reading the position information after power failure is avoided. In addition, the absolute type encoder has a plurality of output codes (binary code, decimal BCD code, gray code) and can be directly supplied to a display unit, a PC, or the like, whereas the incremental type encoder cannot be directly supplied to the display unit. In addition, the absolute encoder can almost not consider the problems of speed, interference and the like, and as long as the encoder stops at a certain position, the absolute encoder can finally display the current position information no matter what influence is received during rotation.
Since the encoder in this example is an absolute encoder, when the servo motor 110 is powered off, the absolute encoder can directly transmit the position information of the bed board 100 to the control unit (MPTC), which is convenient for the control unit (MPTC) to read the position information of the encoder. When the servo drive system is powered on again, the absolute encoder cannot cause the servo drive system to find the zero position again. The problem of abnormal movement of the bed board 100 caused by zero position finding when the servo driving system is electrified again is avoided.
Further, after the servo motor 110 in the servo drive system is powered again, the control unit (MPTC) transmits the position information before power failure back to the servo driver and the encoder. The control unit (MPTC) transmits the position information before power failure back to the encoder, which is beneficial to ensuring that the position of the bed board 100 is consistent with the position of the servo motor 110 before power failure after the servo motor 110 is powered on again.
Optionally, the mri apparatus further includes a speed reducer, and an output end of the servo motor 110 is connected to the bed plate 100 through the speed reducer.
The speed reducer plays a role in matching the rotating speed and transmitting torque between a power source and a mechanical element (in the embodiment, the mechanical element is the bed plate 100). in the embodiment, the speed reducer is additionally arranged between the output end of the servo motor 110 and the bed plate 100 and is used for reducing the rotating speed and increasing the torque. Reducing the rotational speed of the bed plate 100 may increase the torque to enable the bed plate 100 to bear a greater load. Meanwhile, the speed reducer also has the function of increasing the transmission ratio.
Further, the transmission ratio of the speed reducer is greater than or equal to a first set value.
Further, the first set value is greater than or equal to 2.
The transmission ratio is the ratio of the instantaneous input speed to the output speed of the speed reducer, and the general method for representing the reduction ratio is to use 1 as a denominator and use ": "the ratio of the input rotation speed and the output rotation speed is connected, for example, the input rotation speed is 1500r/min, the output rotation speed is 25r/min, then the reduction ratio is i-60: 1. the reduction ratio of a general speed reducing mechanism is marked as an actual reduction ratio, and the larger the transmission ratio is, the larger the output torque is, and the slower the rotating speed is.
The speed reducer has a higher transmission ratio, and can further increase the repeated positioning precision of the bed plate 100. For example, when the positioning error of the servo motor 110 is 1 mm. The servo motor 110 is connected with the bed plate 100 through a speed reducer with a transmission ratio of 2. At this time, the positioning error of the bed plate 100 is 0.5 mm.
It should be noted that a speed reducer with a transmission ratio greater than or equal to a first set value is additionally arranged between the output end of the servo motor 110 and the bed plate 100. When the servo motor 110 is powered on again, even if the servo motor 110 rotates due to the repositioning, the abnormal movement of the bed board 100 is small. Optionally, in the present invention, a transmission ratio of the reducer is greater than 2.
Example two
The same parts as those in the first embodiment will not be described again, and only different points will be described below.
In the first embodiment, the table 100 is driven by a servo driving system and can move only in one direction, and usually the table 100 moves in a horizontal direction to transfer the patient into the scanning imaging unit 200 and to transfer the examined patient out of the scanning imaging unit 200. However, there are often differences in the height of the patient, and there may be inconvenience in the patient. At this time, if the bed board 100 can be moved only horizontally, it is inconvenient for the patient. The couch plate 100 also needs to be moved vertically for the convenience of the patient.
The difference between this embodiment and the first embodiment is: fig. 4 is a schematic diagram of a servo driving system in the present embodiment. As shown in fig. 4, the servo drive system includes a first servo motor 111, a first servo driver, a first encoder, a second servo motor 112, a second servo driver, and a second encoder. The rotating direction and the rotating speed of the first servo motor 111 are controlled through the first servo driver, the bed plate is driven to move back and forth in the first direction through the first servo motor 111, and first position information of the bed plate is obtained through the first encoder. In this embodiment, the second servo driver further controls the rotation direction and the rotation speed of the second servo motor 112, the second servo motor 112 drives the bed board to move back and forth in the second direction, and the second encoder obtains the second position information of the bed board.
In this embodiment, the first direction is a horizontal direction, and the second direction is a vertical direction. In this way, the top board 100 can move in the vertical direction and the horizontal direction. It should be understood that the first position information is position information of the bed board 100 in the horizontal direction, and the second position information is position information of the bed board 100 in the vertical direction.
Further, the bed board 100 further includes a control unit (MPTC), the first encoder is connected to the first servo driver, and the first encoder transmits the first position information of the bed board 100 to the control unit (MPTC) through the first servo driver. The second encoder is connected to the second servo driver, and the second encoder transmits the second position information of the bed board 100 to the control unit (MPTC) through the second servo driver.
Further, the first encoder and the second encoder are both absolute encoders.
When the servo driving system is powered off, the first servo driver, the first servo motor 111, the first encoder, the second servo driver, the second servo motor 112 and the second encoder are powered off, the control unit (MPTC) stores first position information and second position information of the bed board 100, which are acquired by the first encoder and the second encoder at the power-off moment, and when the servo driving system recovers power supply, the control unit (MPTC) returns the stored first position information and second position information to the first encoder and the second encoder. In this way, after the first servo motor 111 or the second servo motor 112 is powered on again, the position of the bed board 100 is ensured to be consistent with the position before power failure.
Correspondingly, in this embodiment, the mri apparatus further includes two speed reducers, and output ends of the first servo motor and the second servo motor in the servo driving system are respectively connected to the scanning bed through one of the speed reducers. Preferably, the transmission ratio of the reducer is greater than 2.
EXAMPLE III
The same parts as those in the first and second embodiments will not be described again, and only different points will be described below.
Fig. 5 is a schematic diagram of a servo driving system in the present embodiment. As shown in fig. 5, the present embodiment is different from the first embodiment in that: the servo drive system includes a servo motor 110, a servo driver, and an encoder. The nuclear magnetic resonance imaging equipment further comprises a power supply unit, and when the servo driving system is powered off, the power supply unit supplies power to the encoder. The encoder is connected to the servo drive and the control unit (MPTC) and can transmit the position information of the encoder via the servo drive to the control unit (MPTC) or transmit the position information directly to the control unit (MPTC).
It should be noted that, because the encoder of the servo motor 110 is powered off, no pulse signal and no position information are fed back to the servo driver, and based on the characteristics of the servo driving system, those skilled in the art should know that the servo driver will have a malfunction alarm. The failure alarm of the servo driver further transmits an alarm signal to the control unit (MPTC), which in turn causes the control unit (MPTC) to force the scanning imaging device to stop. Therefore, the servo drive's alarm signal should be masked during power down of the servo drive. It should be understood that one skilled in the art can solve the problem of the servo driver alarm by inputting a disguised feedback signal (pulse signal) and position information to the servo driver. It should be understood that there are many ways to mask the alarm signal of the servo driver, and those skilled in the art can deal with this according to experience, which will not be described in detail herein.
In this embodiment, the control unit is connected to the encoder, and the mri apparatus further includes a power supply unit, where the power supply unit supplies power to the encoder. When the servo driving system is powered off, the servo driver and the servo motor are powered off, the power supply unit supplies power to the encoder, and the encoder transmits the position information to the control unit in real time. Those skilled in the art should know that the encoder feeds back a signal to the servo driver in real time, and even if the servo driver malfunctions when the servo motor 110 is powered off, the control unit (MPTC) can mask the alarm signal of the servo driver according to the signal (pulse signal) fed back by the encoder in real time.
Further, the power supply unit is a direct current power supply. The direct current power supply is a device for maintaining a stable voltage and a constant current in a circuit, and the electromagnetic interference is caused by the electromagnetic induction principle, and the change of the current of adjacent lines causes the change of a surrounding magnetic field, so the direct current power supply for the stable voltage and the constant current supplies power to the encoder, and the generated electromagnetic interference is very small. The interference generated by the direct current power supply is mainly common mode interference, differential mode inductance can be removed in the design of a filter circuit, and a first-level common mode filter inductance is added. The conducted interference of the direct current power supply can be further reduced.
It will be appreciated that the servo motor 110 is connected to the servo drive by a power line and is powered by the power line. The power line of the servo motor 110 is also called a power line, and the power line is a connecting line for transmitting electric energy between the servo driver and the servo motor 110, and is used for completing the transportation of the electric energy. The servo power line comprises two parts, one part is a connecting line between the servo driver and the power supply, and the other part is a connecting line between the servo driver and the servo motor 110. The power line is usually a line carrying strong electricity, typically 220V or 380V ac. Therefore, when the servo motor 110 is energized, a strong magnetic field is generated around the power line.
The servo motor 110 is powered by the servo driver through the power line, after the power line is powered off, the servo motor 110 and the servo driver are both unpowered, and the encoder is powered by the power supply unit. In this way, the encoder can feed back position information to the control unit (MPTC) in real time. The encoder is powered by a direct current power supply, so that the magnetic generation of the interference source servo motor 110 and the power line which generate the interference magnetic field in the servo driving system can be suppressed, and the interference magnetic field is prevented from influencing the magnetic field in the scanning imaging unit 200.
Example four
The same parts of the nuclear magnetic resonance scanning method provided in this embodiment as those in the first, second, and third embodiments are not described here, and only different points will be described below.
Fig. 6 is a schematic diagram of a servo driving system in the present embodiment. As shown in fig. 6, the servo driving system includes a first encoder, a first servo motor 111, a first servo driver connected to the first encoder, a second servo motor 112, and a second servo driver connected to the second encoder. The first encoder is connected to the first servo driver and the control unit (MPTC) at the same time, and similarly, the second encoder is connected to the second servo driver and the control unit (MPTC) at the same time, so that the first encoder can transmit the first position information to the control unit (MPTC) through the first servo driver, and the second encoder can transmit the second position information to the control unit (MPTC) through the second servo driver, or the first encoder and the second encoder respectively transmit the first position information and the second position information to the control unit (MPTC) in real time and directly.
In this embodiment, the top board 100 can be moved in the vertical direction and the horizontal direction. In this embodiment, the servo driving system includes a first servo motor 111, a first servo driver, a first encoder, a second servo motor 112, a second servo driver, and a second encoder. The difference between this embodiment and the second embodiment is: the bed board 100 further comprises a control unit (MPTC) and a power supply unit, the power supply unit supplies power to the first encoder and the second encoder, and the first encoder and the second encoder are also connected with the control unit (MPTC). Meanwhile, the first servo driver and the second servo driver are connected with the control unit (MPTC), when nuclear magnetic resonance scanning equipment scans and the servo driving system is powered off, the first servo motor 111, the first servo drive, the second servo motor 112 and the second servo drive are powered off, and therefore the servo system cannot generate an interference magnetic field. Further, the first encoder and the second encoder are powered by the power supply unit (i.e., the dc power supply), and the first encoder directly transmits the first position information to the control unit (MPTC) in real time, and the second encoder directly transmits the second position information to the control unit (MPTC) in real time. In this way, when the first servo motor 111 and the second servo motor 112 are powered off, the first servo driver and the second servo driver will not be caused to generate a fault alarm. Moreover, when the first servo motor 111 and the second servo motor 112 are powered on again, the servo driving system does not change again, and the abnormal movement of the bed plate 100 can be further avoided.
EXAMPLE five
The same parts of the nuclear magnetic resonance scanning method provided in this embodiment as those in the first, second, third, and fourth embodiments will not be described again, and only different points will be described below.
Fig. 7 is a schematic diagram of a servo driving system in this embodiment. As shown in fig. 7, optionally, when the servo drive system is powered off, the first servo driver, the first servo motor 111, the second encoder, the second servo motor 112, and the second servo driver are all powered off, the power supply unit supplies power to the first encoder, and the first encoder outputs the first position information to the control unit in real time. (MPTC). Therefore, in this embodiment, only the power supply unit needs to supply power to the first encoder independently, so that the structure of the nuclear magnetic resonance imaging apparatus can be simplified, and the manufacturing cost of the nuclear magnetic resonance imaging apparatus can be reduced.
In order to further understand the method for controlling the movement of the patient bed according to the present invention, the following further introduces the method for controlling the movement of the patient bed in combination with an application scenario of mri.
Fig. 8 is a flowchart of a method for controlling the movement of a patient bed according to the present embodiment. As shown in fig. 8, in the present embodiment, a method for controlling the movement of a patient bed is provided, which includes the following steps:
step S201: the patient lies on the bed board 100 and positions and fixes the patient;
step S202: after the second servo motor 112 drives the bed plate 100 to rise to a set height, the first servo motor 111 drives the bed plate 100 to move to a scanning position inside the scanning imaging unit 200;
step S203: the power line of the second servo motor 112 is powered off from the second encoder, the power line of the first servo motor 111 is powered off, the first encoder is powered on by a direct current power supply, and the first position information of the bed plate 100 is transmitted to a control unit (MPTC);
step S204: after the scanning is finished, electrifying the second servo motor 112 and the first servo motor 111;
step S205: the first servo motor 111 drives the bed plate 100 to horizontally move from the scanning position inside the scanning imaging unit 200 to the set position;
step S206: the second servo motor 112 drives the table board 100 to be lowered to the initial position.
In summary, the present invention provides a method for controlling a motion of a patient bed, which is used for a nuclear magnetic resonance imaging apparatus to perform nuclear magnetic resonance imaging, the nuclear magnetic resonance imaging apparatus includes a patient bed, a servo driving system for driving the patient bed to move, and a scanning imaging unit for imaging, the scanning imaging unit is formed with a scanning aperture, and the method for controlling the motion of the patient bed includes: the servo driving system drives the bed plate to move so as to convey a patient into the scanning aperture; powering off the servo driving system; the scanning imaging unit performs magnetic resonance imaging on a patient. According to the method for controlling the movement of the sickbed, the servo driving system is powered off when nuclear magnetic resonance imaging scanning is carried out, and the servo driving system without power supply cannot generate electromagnetic interference on a scanning imaging unit of nuclear magnetic resonance imaging equipment, so that the imaging effect is improved, and the accuracy of clinical diagnosis is improved.
The above description is only a preferred embodiment of the present invention, and does not limit the present invention in any way. It will be understood by those skilled in the art that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (10)
1. A method for controlling the motion of a sickbed is used for nuclear magnetic resonance imaging of nuclear magnetic resonance imaging equipment, the nuclear magnetic resonance imaging equipment comprises a bedplate, a servo driving system for driving the bedplate to move and a scanning imaging unit for imaging, and a scanning aperture is formed in the scanning imaging unit, and the method for controlling the motion of the sickbed is characterized by comprising the following steps:
the servo driving system drives the bed plate to move so as to convey a patient into the scanning aperture;
powering off the servo driving system;
the scanning imaging unit performs magnetic resonance imaging on a patient.
2. The method of claim 1, wherein the servo drive system comprises a first servo motor, a first servo driver and a first encoder, the first servo driver controls a rotation direction and a rotation speed of the first servo motor, the first servo motor drives the table to move back and forth in a first direction, and the first encoder obtains first position information of the table.
3. The method of bed motion control of claim 2, wherein the mri apparatus further comprises a control unit coupled to the first encoder, the first position information being conveyed to the control unit by the first encoder.
4. The method of claim 3, wherein the first servo driver, the first servo motor and the first encoder are all powered off when the servo drive system is powered off, the control unit stores first position information obtained by the first encoder at the time of power off, and when the servo drive system is powered back on, the control unit transmits the stored first position information back to the first encoder.
5. The method of claim 3, wherein the MRI apparatus further comprises a power supply unit, when the servo drive system is powered off, the first servo driver and the first servo motor are powered off, the power supply unit supplies power to the first encoder, and the first encoder transmits the first position information to the control unit in real time.
6. The method of claim 5, wherein the servo drive system further comprises a second servo motor, a second servo driver, and a second encoder, wherein the second servo driver controls a rotation direction and a rotation speed of the second servo motor, the second servo motor drives the table board to move back and forth in a second direction, and the second encoder obtains second position information of the table board.
7. The method of claim 6, wherein the first servo driver, the first servo motor, the second servo motor and the second servo driver are all powered off when the servo drive system is powered off, the power supply unit supplies power to the first encoder and the second encoder, and the first encoder and the second encoder respectively transmit the first position information and the second position information to the control unit in real time.
8. The method of claim 6, wherein the second encoder is connected to the second servo driver, and the second position information obtained by the second encoder is transmitted to the control unit via the second servo driver.
9. The method of claim 8, wherein the first servo driver, the first servo motor, the second encoder, the second servo motor and the second servo driver are all powered off when the servo drive system is powered off, the power supply unit supplies power to the first encoder, and the first encoder transmits the first position information to the control unit in real time.
10. The method of claim 2 or 6, wherein the mri apparatus further comprises two speed reducers, the output ends of the first and second servo motors of the servo drive system are respectively connected to the table plate through one speed reducer, and the transmission ratio of the speed reducers is greater than or equal to 2.
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