CN115933770A - Automatic rapid switching collimator system for realizing precise motion control - Google Patents
Automatic rapid switching collimator system for realizing precise motion control Download PDFInfo
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Abstract
The invention discloses an automatic fast switching collimator system capable of realizing accurate motion control and an accurate motion control method, comprising a collimator mechanism, a turntable mechanism, a primary position feedback mechanism, a secondary position feedback mechanism, a fixing mechanism and an electric control mechanism; the primary position feedback mechanism comprises a rotor position detection sensor for monitoring the position of the stepping motor in real time and automatically switching open-loop and closed-loop control according to conditions; the secondary position feedback mechanism comprises a grating, a reading head and a data acquisition and conversion module; the grating reading head reads the scale code of the grating and transmits the scale code to the electric control mechanism through the data acquisition and conversion module to realize closed-loop control. The collimator also comprises a protection disc mechanism, and the collimator is replaced and protected by a rotatable multi-blade protection disc and a proximity switch detector. The invention realizes convenient operation of the protection disc, reduces the replacement time and saves the treatment time; and the error caused by the transmission link is reduced by directly measuring the value through the grating.
Description
Technical Field
The invention relates to an automatic quick switching collimator device for realizing accurate motion control, in particular to a secondary collimator device which is used for a radiosurgery robot system and can realize automatic quick switching of accurate motion control.
Background
In recent years, radiation therapy techniques and equipment have changed dramatically, and conventional radiation therapy is shifting toward precision radiosurgery. The precise radiosurgery treatment refers to a new radiotherapy technology for 'precise diagnosis, precise positioning, precise planning and precise treatment' of tumors. The radiosurgery technology can obviously improve the local control rate of the tumor and reduce the complications of normal tissues, thereby improving the treatment effect, in particular the precise stereotactic radiotherapy technology is used for 1 to 5 times, the treatment dosage of large-dose irradiation is given to the tumor, and the traditional conventional radiotherapy dosage mode is overturned. The essence of these techniques is that the beam is accurately focused in the tumor focus area by expanding and optimizing the treatment space and using multiple beams of non-coplanar high-dose small-field irradiation, so that the dose distribution is rapidly and sharply reduced in the range of millimeter at the edge of the target volume, thereby reducing the damage to surrounding normal tissues and greatly improving the adaptability and treatment effect of radiotherapy. Therefore, the positioning precision and the irradiation precision of radiotherapy are improved, and the adoption of the individual precise radiosurgery technology with large dose and low frequency is the future development direction of the radiotherapy technology.
The 2022100459784 patent discloses a collimation system capable of automatic fast switching, wherein at least 2 collimators are simultaneously mounted on a treatment head, and the treatment head can fast switch the collimators according to a treatment plan during treatment. In most cases, the collimator can be replaced without stopping treatment, so that the automatic and quick-switching collimation system is realized, and the treatment time is saved. In the treatment process of the collimation system, the secondary collimator accurately and quickly moves to a specified station, which is a key step. However, in the moving process of treatment, due to the weight influence of the loaded collimator, part of components can be deformed, so that the position of the motor is easy to shift in the rotating process, especially under the condition that the collimators are in different postures caused by the movement of the robot, the secondary collimator is not directly driven to rotate by the same angle due to different loads, the plane precision deviation of the patient obtained by the accumulation of all factors is large, and the treatment effect can be influenced. And the complete beam axis coincidence of the secondary collimator and the primary collimator is difficult to ensure by only depending on the motor movement positioning and locking, so that the treatment beam is deformed, and the treatment effect is influenced.
Disclosure of Invention
In order to solve the technical problems, the invention discloses an automatic fast switching collimator system for realizing accurate motion control, wherein a plurality of secondary collimators with different apertures are arranged on a turntable mechanism in an accelerator head, the automatic rotation, automatic identification and automatic locking of the turntable mechanism are realized through a primary position feedback system, a secondary position feedback system carries out real-time feedback to correct the position deviation of the primary position feedback system, and in the automatic fast replacement process of a plurality of collimators with different apertures arranged on the turntable mechanism in one treatment fraction, the real-time feedback of position information is realized, the closed-loop communication of the accurate motion control and the accurate motion control of different collimators are realized, the automatic fast switching is realized, and the treatment time is saved.
The complete technical scheme of the invention comprises the following steps:
an automatic fast switching collimator system capable of realizing precise motion control comprises a collimator mechanism, a turntable mechanism, a primary position feedback mechanism, a secondary position feedback mechanism, a fixing mechanism and a control circuit;
the collimator mechanism comprises at least 2 secondary collimators, the collimator mechanism is arranged on the turntable mechanism, and the turntable mechanism can drive the collimator mechanism to rotate and rotate the specified collimators to the position below the beam aperture;
the primary position feedback mechanism includes: the stepping motor is connected with the turntable mechanism and drives the turntable mechanism to rotate under the instruction of the driver, and the stepping motor is provided with a rotor position detection sensor which monitors the position of the stepping motor in real time and automatically switches open-loop and closed-loop control according to conditions;
the secondary position feedback mechanism comprises a grating, a reading head and a data acquisition and conversion module; the grating reading head reads the scale code of the grating and transmits the scale code to the control circuit through the data acquisition and conversion module.
Furthermore, the primary position feedback mechanism further comprises a motor support, a coupler and an electromagnetic push rod assembly, the stepping motor is installed on the motor support and is connected with the coupler, and the coupler is connected with the turntable mechanism.
Furthermore, the primary position feedback mechanism is provided with a zero clearance type hard gear zero searching mechanism and a turntable bidirectional limit switch detection mechanism, accurate calibration of initial zero position of the turntable is realized through a hard stop block arranged on the fixing mechanism, and the turntable limit protection and alarm functions are realized through 2 forward and reverse over-travel limit switches arranged on the fixing mechanism; programmable control of the motor driver is achieved through an isolated RS485 communication interface circuit, a function of quickly switching stations is achieved, and a double locking mode of motor torque locking and electromagnetic push rod locking is adopted.
Further, the primary position feedback mechanism includes open-loop control and closed-loop control, usually open-loop control, that is, real-time detection of the motor action while executing open-loop control; switching to closed-loop control when position deviation occurs on the command and the motor position due to overload, thereby correcting the position and the speed;
and a secondary position feedback mechanism is added on the basis of the closed-loop positioning operation of the primary position feedback mechanism to serve as a final closed-loop target, so that the influence of the deformation of a transmission link between the output shaft of the motor and a load at the tail end on the output positioning is eliminated.
Furthermore, the collimator system also comprises a protection disc mechanism, wherein the protection disc mechanism comprises a rotatable multi-blade protection disc and a proximity switch detector, the rotatable multi-blade protection disc is connected with the system in a mechanical quick connection mode, can rotate at an angular direction, and in normal work, each blade of the multi-blade protection disc rotates to the position right below the collimator to prevent the collimator from falling off to the ground when the locking of the collimator fails; at the moment, the proximity switch detector can detect that the rotary multi-blade protection disc rotates to a working position and output a corresponding signal; when the collimator needs to be replaced after treatment is finished, the blades of the multi-blade protection disc rotate to the middle of the two collimators and do not block the collimator from coming out or coming in any more, and the proximity switch cannot detect that the multi-blade protection disc is in the working position at the moment and outputs corresponding signals; after the collimator is replaced, the multi-blade rotary protection disc is rotated to be right below the collimator to restore the protection function of the collimator, and the proximity switch detects a signal of the multi-blade rotary protection disc at a working position and outputs a corresponding signal.
Furthermore, the control circuit is externally connected with a grating reading head and an a-STEP driver, and the a-STEP driver is directly connected with an a-STEP stepping motor to control the movement of the multi-station turntable mechanism;
the control circuit comprises a power module, a communication module, a collimator physical coding module, an electromagnetic push rod driving and position feedback module and a protection disc detection module;
the power supply module adopts a two-stage isolation mechanism, wherein one stage is power supply and control power supply isolation, and the control power supply is obtained from power supply and is realized by voltage reduction isolation type DC/DC conversion; the other level is the isolation of communication power supply and control power supply, is taken from the control power supply and is realized by the conversion of an isolation type communication chip;
the electromagnetic push rod driving and position feedback module adopts a PWM pulse width regulation design, the pulse width regulation range is 0-300 mu s, the current of the coil is reduced to 10% of a rated value in time after the current is started and instantly attracted in place, and the continuous work of the coil is ensured; the continuous adjustment of the continuous small-power holding current after the instantaneous high-power pull-in and pull-in are in place is realized by adjusting the PWM duty ratio in real time in the pull-in process. The PWM duty cycle is also adjusted in real time during the current off period to reduce mechanical shock.
The method for realizing the accurate motion control of the collimator by utilizing the collimator system completes the zero point initialization of the motor through a hard stop block and a limit switch detection mechanism, and performs the initialization processing of the motor according to the grating value fed back by the secondary feedback positioning mechanism and the theoretical value of the primary feedback positioning system;
then the primary feedback positioning mechanism realizes primary automatic movement, automatic positioning and locking by means of an a-STEP closed loop; the secondary feedback positioning mechanism feeds back position information according to instant information, and the primary feedback positioning mechanism carries out compensation motion and deviation correction according to the fed back position information to realize secondary closed-loop control.
Further, the method for controlling the accurate movement of the collimator specifically comprises the following steps:
(1) Initializing a zero point of the motor;
(2) The motor initialization processing, taking the grating position value as a theoretical value of a 'preset position', after the motor moves, recording the grating position value as an initial theoretical value of the motor when the grating position value is consistent with the theoretical value, and finishing the initialization;
(3) The upper computer sends a command to the control circuit of the secondary collimator and feeds back the command to the a-STEP driver, a motion command is sent, the push rod locks the closing of the detection switch, the electromagnetic push rod is electrified to reduce the current of the coil to 10% of the rated value in time, and the electromagnetic push rod is pulled out of the fixing mechanism;
(4) The a-STEP stepping motor realizes the ultrahigh resolution of the angle and enough motor output torque by an ultrahigh reduction ratio of 100, and realizes the primary motion positioning; a-STEP stepping motor is internally provided with fine-parting rotary encoder data, and the fine-parting rotary encoder data is fed back to a driving front stage through a speed reducer and a transmission mechanism to realize position first-stage closed loop;
(5) After the push rod moves in place, the push rod locking detection switch is switched off, the PWM duty ratio is adjusted, the electromagnetic push rod moves stably to the fixing mechanism, primary accurate positioning and locking are achieved, and movement information is returned to the a-STEP driver;
(6) The grating reading head reads the grating position in real time and judges the grating position reading and the theoretical position threshold range;
(7) Calculating the movement direction and the step number of the motor according to the current position and the position to be moved to the station, and sending a movement instruction to the motor; when the position of the grating deviates from the range of the theoretical position delta, the control circuit sends a correction command to the motor and the driver, the current position is moved to the range of the ideal position, the angle deviation is corrected, and secondary closed-loop control is realized; and repeating the above steps (4) - (7);
(8) After the rotation mechanism stops moving, the absolute value of the error between the grating reading and the target constant is smaller than the theoretical position delta, and the electromagnetic push rod enters the hole to be locked and triggers the micro switch to return to the position to be sent to the upper computer.
Further, the motor zero point initialization includes: the device is provided with 2 overtravel limit points for forward and reverse rotation, a microswitch is adopted to detect the relative position of the rotating mechanism and the fixing mechanism, a reverse limit point of the rotating mechanism is set as a positioning original point, a press-contact mode is adopted to search the positioning original point, and the device rotates anticlockwise and observes the reading of a grating and a motor encoder on the end face of the rotating mechanism of the secondary collimator; and the rotating mechanism rotates reversely to find an original point, the collimator rotates forwards after the original point is confirmed, and each station of the collimator sequentially passes through the beam flow hole.
Further, the motor initialization process comprises the following steps:
(1) After the zero point of the motor is initialized, obtaining a motor stop position END =1, and if yes, giving an alarm without ALM; if not, stopping the motor and feeding back;
(2) If no ALM alarm is yes, the raster position value of the motor is refreshed, the raster position value is assigned to a 'preset position' register, starting data are written in the register, and the motor automatically updates the 'preset position' value; if not, refreshing local alarm information display and reporting data packet processing;
(3) The motor executes a motion command, the motion command is distributed and operated to each station, the conformity of the grating value and the theoretical value is verified, and the out-of-tolerance condition of the motor, the real-time data of the grating and the theoretical value is judged;
(4) If the real-time data of the motor and the grating and the theoretical value are not out of tolerance, respectively storing the latest station position parameters, and finishing initialization; if the real-time data of the motor and the grating are out of tolerance with the theoretical value, initializing and reporting a wrong initialization failure mark, and finishing initialization.
Compared with the prior art, the invention has the advantages that:
1. the invention realizes the accurate calibration of the initial zero position of the rotary table through the two-way limit switch, and adopts the primary position feedback mechanism and the secondary position feedback mechanism to realize the secondary closed-loop control of the rotary table mechanism, and the direct measurement value of the grating is accurate, thereby eliminating the error caused by the deformation of the components due to the overload of the collimator in the transmission link.
2. Adopt rotatable three leaf protection discs to protect the collimator, through reasonable structural control, the simple operation need not take off and can change, reduces the change time, has practiced thrift treatment time.
Drawings
FIG. 1 is a diagram of an automatic fast switching collimator system capable of implementing precise motion control according to the present invention;
FIG. 2 is a diagram of a primary feedback positioning mechanism;
FIG. 3 is a structural view of a protection disk mechanism;
FIG. 4 is a graph of electromagnetic pin turn-on and turn-off current versus time;
FIG. 5 is a flow chart of a method of precision motion control;
fig. 6 is a flowchart of the motor initialization process.
Detailed Description
The present invention is described in detail below with reference to the following embodiments and the attached drawings, but it should be understood that the embodiments and the attached drawings are only used for the illustrative description of the present invention and do not limit the protection scope of the present invention in any way. All reasonable variations and combinations that fall within the spirit of the invention are intended to be within the scope of the invention.
An automatic fast switching collimator system capable of implementing precise motion control as shown in fig. 1-3 comprises: a primary position feedback mechanism, a turntable mechanism 1, a fixing mechanism 2, a secondary position feedback mechanism, a collimator mechanism 3, a protection disc mechanism 4 and a control circuit 5.
The primary position feedback mechanism comprises a driver 6, a stepping motor 7, a motor bracket 8, a coupler and an electromagnetic push rod assembly 9. The stepping motor is arranged on the motor support and is simultaneously connected with the coupler, and the coupler is connected with the turntable mechanism. The driver and stepper motor are of the a-STEP type.
The primary position feedback mechanism is provided with a zero-clearance type hard gear zero-searching mechanism and a turntable bidirectional limit switch detection mechanism so as to realize accurate calibration of initial zero position of the turntable and the functions of turntable limit protection and alarm; programmable control of the motor driver is achieved through an isolated RS485 communication interface circuit, a function of quickly switching stations is achieved, and a double locking mode of motor torque locking and electromagnetic push rod locking is adopted.
The fixing mechanism is provided with a limit switch support, and the limit switch support is provided with a positive and a negative pressure-contact limit switches 10. The zero-clearance type hard gear zero-seeking mechanism of the primary position feedback mechanism refers to that a stepping motor reversely seeks zero at a low speed, when a mechanical support rod structure arranged on a rotary disc collides with a limit switch bracket, the torque of the motor is increased, and when the torque of the motor is increased to 50% of the bearing torque of the motor, the motor is considered as a zero point, and zero seeking is finished. The turntable bidirectional limit switch detection mechanism means that a limit switch support is provided with a positive pressure contact limit switch and a negative pressure contact limit switch, except a zero searching process, a mechanical support rod structure on a rotating disk is contacted with the pressure contact limit switches at any time, the rotation of the motor is considered to exceed the circumferential rotation position, and the rotation of the motor is stopped immediately at the moment.
The primary position feedback mechanism monitors the position of the motor in real time through the rotor position detection sensor and automatically switches open-loop control and closed-loop control according to conditions. Normally, the control circuit is open-loop control, and executes the open-loop control while detecting the action of the motor, namely, the control circuit calculates the step number of the direction in which the motor needs to move and sends the motion information to the motor driver, and the motor completes the motion in the required direction and step number according to the command of the driver.
When the position deviation occurs on the command and the motor position due to overload and the like, the closed-loop control is immediately switched to, namely when the position information fed back by the grating ruler is inconsistent with the theoretical position information, the closed-loop control is started, so that the position and the speed are corrected. Specifically, the control circuit calculates the deviation between the current position and the theoretical position to form an instruction of the movement direction and the step number of the motor, the motor finishes the instruction of the control circuit, the grating ruler feeds back the real-time position after the motor finishes the movement and compares the real-time position with the theoretical value, if the motor stops the movement within the reasonable range of the theoretical position, the process of calculating the deviation, forming the movement instruction and finishing the movement of the motor is repeated if the motor does not stop the movement within the reasonable range of the theoretical position, and the reading of the grating ruler and the theoretical position are within the reasonable range.
According to the invention, the secondary position feedback mechanism is added on the basis of the closed-loop positioning operation of the primary position feedback mechanism to serve as a final closed-loop target, so that the influence of the deformation of a transmission link (such as a coupling) between the output shaft of the motor and a load at the tail end on the output positioning is eliminated.
The secondary position feedback mechanism comprises a grating 11, a reading head 12 and a data acquisition and conversion module. The grating surrounds the outer side of the turntable mechanism and is fixed through screws. When the rotor of the stepping motor rotates along the axial direction of the spindle of the stepping motor, the turntable mechanism drives the grating to synchronously move along with the rotor of the stepping motor. The grating reading head and the limit switch are arranged at the same part of the fixing mechanism and are far away from the beam axis direction.
The grating is externally marked with scales in a coding mode, the reading head is arranged outside the grating, the reading head emits laser, the grating reflects the laser with scale codes to the inside of the reading head, and the reading head receives and processes the laser with the code scales and sends the laser to the control circuit.
Install protection plate mechanism at the collimator end, protection plate mechanism contains rotatable three leaf protection plate 13 and proximity switch detector, and operating condition only needs swivel nut with change the collimator state to switch over, simultaneously, adopts the proximity switch detector to detect whether protection plate mechanism is in normal protection state, and the purpose of quick replacement collimator can be realized to the output signal of telecommunication.
The three-blade protection disk of the protection disk mechanism is connected with a system in a mechanical quick connection mode, is axially locked and fixed by 6 balls after being connected, and can still rotate at an angular direction, namely on a plane vertical to the axial direction. When the three-blade protective disc works normally, each blade of the three-blade protective disc rotates to the position right below the collimator, and the collimator can be effectively prevented from falling off to the ground when the locking of the collimator fails. At the moment, the proximity switch detector can just detect that the three-blade rotary protection disc rotates to a working position, and outputs a protected signal. The proximity switch detector is a loose GX-F8 series proximity switch. When the collimator needs to be replaced after treatment is finished, the blades of the three-blade protection disc are rotated to the middle of the two collimators, the part does not block the collimator from coming out or coming in, the replacement of the collimator is not influenced, the proximity switch cannot detect that the three-blade protection disc is in a working position at the moment, and an 'unprotected' signal is output. After the collimator is replaced, the three-leaf rotary protection disc is rotated to a position (working position) right below the collimator, the mechanism recovers the protection function of the collimator, and the proximity switch detects a signal that the three-leaf rotary protection disc is in the working position and outputs a protected signal.
The collimator mechanism 3 comprises at least 2 groups of collimators and a probe PCB, the collimators are connected with the turntable mechanism, grooves are formed above the collimators, metal probes are arranged on the probe PCB, the outer diameter of the PCB is smaller than the outer diameter of a collimator cylinder, and the inner diameter of the PCB is larger than the inner diameter of a collimator cylinder with the largest aperture. The collimator adopts a symmetrical locking structure, so that the positioning error caused by the asymmetrical locking structure can be effectively avoided. See in particular patent 2022100459784.
The control circuit 5 is provided with a power supply module, a communication module with a superior system, a collimator physical coding module, an electromagnetic push rod driving and position feedback module and a protection disc detection module, the control circuit is externally connected with a grating reading head and an a-STEP driver, and the a-STEP driver is directly connected with an a-STEP stepping motor to control the movement of the multi-station turntable.
The total input end of the power module is designed with a TVS (Transient Voltage Suppressor) circuit which is used for protecting a control circuit from electrostatic discharge and effectively suppressing surge impact of 400W (10/1000 mu s). A two-stage isolation mechanism is adopted, wherein one stage is power supply and control power supply isolation, and the control power supply is taken from power supply and is realized by voltage reduction isolation type DC/DC conversion; the first level is communication power supply and control power supply isolation, is obtained from control power supply and is realized through isolation type communication chip conversion.
As shown in fig. 4, the electromagnetic push rod driving and position feedback module is designed with a PWM pulse width modulation technique, where the pulse width modulation range is 0-300 microseconds, so as to reduce mechanical impact to the maximum extent, reduce coil current after the electromagnetic push rod is attracted to ensure that the consumed power is not exceeded, and reduce the coil current to 10% of the rated value in time after the current is turned on and attracted to the right position, thereby ensuring that the coil continuously operates at a voltage of 24V. The continuous adjustment of the continuous low-power holding current after instant high-power pull-in and pull-in place can be realized by adjusting the PWM duty ratio in real time in the pull-in process. During the current closing period, the PWM duty ratio also needs to be adjusted in real time so as to achieve the slow release effect and reduce the mechanical impact.
The invention also discloses a precise motion control method, as shown in fig. 5, the zero point initialization of the motor is completed through a hard gear and limit switch detection mechanism, the motor initialization processing is carried out according to the grating value fed back by a secondary feedback positioning mechanism and the theoretical value of a primary feedback positioning system, the primary feedback positioning mechanism realizes primary automatic motion, automatic positioning and locking by means of a-STEP closed loop, the secondary feedback positioning mechanism feeds back position information in real time, and the primary feedback positioning mechanism carries out compensation motion and deviation correction according to the information to realize secondary closed loop control. The method comprises the following steps:
(1) Initializing a zero point of a motor;
(2) Initializing, namely taking the grating position value as a theoretical value of a 'preset position', after the motor moves, recording the grating position value as an initial theoretical value of the motor when the grating position value is consistent with the theoretical value, and finishing initialization;
(3) The upper computer sends a command to the control circuit of the secondary collimator and feeds the command back to the a-STEP driver, a motion command is sent, the push rod locks the closing of the detection switch, the electromagnetic push rod is electrified, the current of the coil is timely reduced to 10% of the rated value, and the electromagnetic push rod is pulled out of the fixing mechanism;
(4) The a-STEP stepping motor realizes angular ultrahigh resolution and enough motor output torque by means of 100 ultrahigh reduction ratio, and realizes primary motion positioning; the a-STEP stepping motor is internally provided with fine-dividing type rotary encoder data, the fine-dividing type rotary encoder data is fed back to a driving front stage through a speed reducer and a transmission mechanism to realize position first-stage closed loop, a first-stage closed loop network is inserted into a biquad filtering algorithm, fine-dividing gaps and transmission jitter can be effectively eliminated, and the stable positioning of the a-STEP stepping motor is ensured;
(5) After the push rod moves in place, the push rod locking detection switch is switched off, the PWM duty ratio is adjusted, the electromagnetic push rod moves to the fixing mechanism slowly, primary accurate positioning and locking are achieved, and movement information is returned to the a-STEP driver;
(6) The grating reading head reads the grating position in real time and judges the grating position reading and the theoretical position threshold range;
(7) When the position of the grating deviates from the range of the theoretical position delta, the control circuit sends a correction command to the motor and the driver, the current position is moved to the range of the ideal position, the angle deviation is corrected, and the secondary closed-loop control is realized, wherein the range of the theoretical position delta is +/-0.018 degrees in the embodiment;
(8) After the rotation mechanism stops moving, the absolute value of the error between the grating reading and the target constant is smaller than delta, and the electromagnetic push rod enters the hole to be locked and triggers the micro switch to return to the in-place signal to the upper computer;
the motor is initialized at zero point, has forward and reverse rotation 2 overtravel limits and adopts a microswitch for detection. The relative position of the rotating mechanism and the fixing mechanism sets the reverse limit of the rotating mechanism as a positioning original point, and the original point search adopts a press-contact mode supported by a driver. And when the end face of the rotating disk part of the secondary collimator is observed in the reverse beam direction, the reading of the grating and the motor encoder is increased when the rotating disk rotates clockwise (forward), and the reading is reduced when the rotating disk rotates anticlockwise (reverse). The slewing mechanism reverse rotation seeks the initial point, and the initial point is confirmed the back forward rotation, 1# station, 2# station, blind hole, 3# station, in proper order through the restricted aperture. As shown in fig. 6, the specific process steps are as follows:
(1) After the zero point of the motor is initialized, obtaining a motor stop position END =1, and if yes, giving an alarm without ALM; if not, stopping the motor and feeding back;
(2) If no ALM alarm is yes, the raster position value of the motor is refreshed, the raster position value is assigned to a 'preset position' register, starting data are written in the register, and the motor automatically updates the 'preset position' value; if not, refreshing local alarm information display and reporting data packet processing;
(3) The motor executes a motion command, the motion command is distributed and operated to each station, the conformity of the grating value and the theoretical value is verified, and the out-of-tolerance condition of the motor, the real-time data of the grating and the theoretical value is judged;
(4) If the real-time data of the motor and the optical grating and the theoretical value are not out of tolerance, respectively storing the latest station position parameters, and finishing initialization; if the real-time data of the motor and the grating are out of tolerance with the theoretical value, initializing and reporting a wrong initialization failure mark, and finishing initialization.
The above applications are only some embodiments of the present application. It will be apparent to those skilled in the art that various changes and modifications can be made without departing from the inventive concept herein, and it is intended to cover all such modifications and variations as fall within the scope of the invention.
Claims (10)
1. An automatic fast switching collimator system capable of realizing precise motion control is characterized by comprising a collimator mechanism, a turntable mechanism, a primary position feedback mechanism, a secondary position feedback mechanism, a fixing mechanism and a control circuit;
the collimator mechanism comprises at least 2 secondary collimators, the collimator mechanism is arranged on the turntable mechanism, and the turntable mechanism can drive the collimator mechanism to rotate and rotate the specified collimators to the position below the beam aperture;
the primary position feedback mechanism includes: the stepping motor is connected with the turntable mechanism and drives the turntable mechanism to rotate under the instruction of the driver, and the rotor position detection sensor monitors the position of the stepping motor in real time and automatically switches open-loop and closed-loop control according to conditions;
the secondary position feedback mechanism comprises a grating, a reading head and a data acquisition and conversion module; the grating reading head reads the scale code of the grating and transmits the scale code to the control circuit through the data acquisition and conversion module.
2. The automatic fast switching collimator system capable of realizing precise motion control according to claim 1, wherein the primary position feedback mechanism further comprises a motor support, a coupler and an electromagnetic push rod assembly, the stepping motor is installed on the motor support and is connected with the coupler, and the coupler is connected with the turntable mechanism.
3. The automatic fast switching collimator system capable of realizing precise motion control according to claim 2, wherein the primary position feedback mechanism has a zero-clearance type hard stop zero-searching mechanism and a rotary disc bidirectional limit switch detection mechanism, the precise calibration of the initial zero position of the rotary disc is realized through a hard stop block arranged on the fixing mechanism, and the limit protection and alarm functions of the rotary disc are realized through 2 forward and reverse over-travel limit switches arranged on the fixing mechanism; programmable control of a motor driver is achieved through an isolated RS485 communication interface circuit, a rapid station switching function is achieved, and a double locking mode of motor torque locking and electromagnetic push rod locking is adopted.
4. An automatic fast-switching collimator system capable of realizing precise motion control according to claim 3, wherein the primary position feedback mechanism comprises open-loop control and closed-loop control, and the open-loop control is usually adopted, that is, the action of the motor is detected in real time and the open-loop control is executed at the same time; switching to closed-loop control when position deviation occurs on the command and the motor position due to overload, thereby correcting the position and the speed;
and a secondary position feedback mechanism is added on the basis of the closed-loop positioning operation of the primary position feedback mechanism to serve as a final closed-loop target, so that the influence of the deformation of a transmission link between the output shaft of the motor and a load at the tail end on the output positioning is eliminated.
5. The automatic fast switching collimator system capable of realizing precise motion control of claim 1, further comprising a protection disc mechanism, wherein the protection disc mechanism comprises a rotatable multi-leaf protection disc and a proximity switch detector, the rotatable multi-leaf protection disc is connected with the system in a mechanical fast connection mode, and can rotate in an angular direction, and in normal operation, each leaf of the multi-leaf protection disc rotates to a position right below the collimator to prevent the collimator from falling to the ground when the collimator locking fails; at the moment, the proximity switch detector can detect that the rotary multi-blade protection disc rotates to a working position and output a corresponding signal; when the collimator needs to be replaced after treatment is finished, the blades of the multi-blade protection disc rotate to the middle of the two collimators and do not block the collimator from coming out or coming in any more, and the proximity switch cannot detect that the multi-blade protection disc is in the working position at the moment and outputs corresponding signals; after the collimator is replaced, the multi-blade rotary protection disc is rotated to be right below the collimator to restore the protection function of the collimator, and the proximity switch detects a signal of the multi-blade rotary protection disc at a working position and outputs a corresponding signal.
6. The automatic fast switching collimator system capable of realizing precise motion control according to claim 1, wherein the control circuit is externally connected with a grating reading head and an a-STEP driver, and the a-STEP driver is directly connected with an a-STEP stepping motor to control the motion of the multi-station turntable mechanism;
the control circuit comprises a power module, a communication module, a collimator physical coding module, an electromagnetic push rod driving and position feedback module and a protection disc detection module;
the power supply module adopts a two-stage isolation mechanism, wherein one stage is power supply and control power supply isolation, and the control power supply is obtained from power supply and is realized by voltage reduction isolation type DC/DC conversion; the other level is the isolation of communication power supply and control power supply, is taken from the control power supply and is realized by the conversion of an isolated communication chip;
the electromagnetic push rod driving and position feedback module adopts a PWM pulse width regulation design, the pulse width regulation range is 0-300 mu s, the current of the coil is timely reduced to 10% of a rated value after the current is started and is sucked in place instantly, and the continuous work of the coil is ensured; the continuous adjustment of the continuous small-power holding current after the instantaneous high-power pull-in and pull-in are in place is realized by adjusting the PWM duty ratio in real time in the pull-in process. The PWM duty cycle is also adjusted in real time during the current off period to reduce mechanical shock.
7. The method for realizing the accurate motion control of the collimator by using the collimator system of any one of claims 1-6, characterized in that the motor zero point initialization is completed by a hard stop block and limit switch detection mechanism, and the motor initialization processing is performed according to the grating value fed back by the secondary feedback positioning mechanism and the theoretical value of the primary feedback positioning system;
then the primary feedback positioning mechanism realizes primary automatic movement, automatic positioning and locking by means of an a-STEP closed loop; the secondary feedback positioning mechanism feeds back position information according to instant information, and the primary feedback positioning mechanism carries out compensation motion and deviation correction according to the fed back position information to realize secondary closed-loop control.
8. The method for controlling the precise movement of the collimator according to claim 7, comprising the following steps:
(1) Initializing a zero point of the motor;
(2) The motor initialization processing, taking the grating position value as a theoretical value of a 'preset position', after the motor moves, recording the grating position value as an initial theoretical value of the motor when the grating position value is consistent with the theoretical value, and finishing the initialization;
(3) The upper computer sends a command to the control circuit of the secondary collimator and feeds back the command to the a-STEP driver, a motion command is sent, the push rod locks the closing of the detection switch, the electromagnetic push rod is electrified to reduce the current of the coil to 10% of the rated value in time, and the electromagnetic push rod is pulled out of the fixing mechanism;
(4) The a-STEP stepping motor realizes the ultrahigh resolution of the angle and enough motor output torque by an ultrahigh reduction ratio of 100, and realizes the primary motion positioning; a-STEP stepping motor is internally provided with fine-parting rotary encoder data, and the fine-parting rotary encoder data is fed back to a driving front stage through a speed reducer and a transmission mechanism to realize position first-stage closed loop;
(5) After the push rod moves in place, the push rod locking detection switch is switched off, the PWM duty ratio is adjusted, the electromagnetic push rod moves stably to the fixing mechanism, primary accurate positioning and locking are achieved, and movement information is returned to the a-STEP driver;
(6) The grating reading head reads the grating position in real time and judges the grating position reading and the theoretical position threshold range;
(7) Calculating the movement direction and the step number of the motor according to the current position and the position to be moved to the station, and sending a movement instruction to the motor; when the position of the grating deviates from the range of the theoretical position delta, the control circuit sends a correction command to the motor and the driver, the current position is moved to the range of the ideal position, the angle deviation is corrected, and secondary closed-loop control is realized; and repeating the above steps (4) - (7);
(8) After the rotation mechanism stops moving, the absolute value of the error between the grating reading and the target constant is smaller than the theoretical position delta, and the electromagnetic push rod is locked by the inlet hole and triggers the microswitch to return to the upper computer.
9. The method of fine motion control of a collimator of claim 8, wherein the motor zero initialization comprises: the device is provided with 2 overtravel limit points for forward and reverse rotation, a microswitch is adopted to detect the relative position of the rotating mechanism and the fixing mechanism, a reverse limit point of the rotating mechanism is set as a positioning original point, a press-contact mode is adopted to search the positioning original point, and the device rotates anticlockwise and observes the reading of a grating and a motor encoder on the end face of the rotating mechanism of the secondary collimator; and the rotating mechanism is rotated reversely to find an original point, the collimator rotates forwards after the original point is confirmed, and each station of the collimator sequentially passes through the beam current hole.
10. The method for accurate motion control of a collimator according to claim 9, wherein the motor initialization procedure comprises the following steps:
(1) After the motor zero point is initialized, obtaining a motor stop bit END =1, and if yes, giving an alarm without ALM; if not, stopping the motor and feeding back;
(2) If no ALM alarm is yes, the raster position value of the motor is refreshed, the raster position value is assigned to a 'preset position' register, starting data are written in the register, and the motor automatically updates the 'preset position' value; if not, refreshing local alarm information display and reporting data packet processing;
(3) The motor executes a motion command, the motion command is distributed and operated to each station, the conformity of the grating value and the theoretical value is verified, and the out-of-tolerance condition of the motor, the real-time data of the grating and the theoretical value is judged;
(4) If the real-time data of the motor and the optical grating and the theoretical value are not out of tolerance, respectively storing the latest station position parameters, and finishing initialization; if the real-time data of the motor and the grating are out of tolerance with the theoretical value, initializing and reporting a wrong initialization failure mark, and finishing initialization.
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| CN202211580708.XA CN115933770B (en) | 2022-12-07 | 2022-12-07 | Automatic and rapid switching collimator system for realizing accurate motion control |
| EP23740082.5A EP4344737A1 (en) | 2022-01-17 | 2023-01-13 | Collimator device and motion control method therefor |
| PCT/CN2023/072061 WO2023134741A1 (en) | 2022-01-17 | 2023-01-13 | Collimator device and motion control method therefor |
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| CN202211580708.XA CN115933770B (en) | 2022-12-07 | 2022-12-07 | Automatic and rapid switching collimator system for realizing accurate motion control |
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