Position feedback method for scanning frame

Abstract

The embodiment of the invention discloses a position feedback method for a scanning frame. The method comprises the steps that a motion controller is used for receiving a control instruction and sending a control signal to a servo driver; the servo driver is used for sending a driving signal to a servo motor; a servo motor is used for driving a horizontal movement module to move along a horizontal supporting frame of a scanning frame, the horizontal supporting frame comprises n grating rulers, the adjacent grating rulers have overlapped parts, n-1 position calibration points are arranged in the n-1 overlapped parts, and the horizontal movement module comprises n reading heads corresponding to the n grating rulers; reading position data fed back by the (i-1) th grating ruler by using the (i-1) th reading head, and feeding back the position data to the motion controller (1lt) through the encoder reading module; i < = n; and sending a switching signal to the horizontal motion module by using the motion controller, so that the horizontal motion module switches the ith reading head at the (i-1) th position calibration point to read position data fed back by the ith grating ruler.

Description

Technical Field

[0001] This invention relates to The field of compression field technology. More specifically, it relates to a position feedback method for a scanning gantry. Background Technology

[0002] Compact field technology utilizes the near-field focusing principle, converting the spherical waves generated by the feed source into plane waves through a precision reflecting surface, enabling far-field measurement of antenna parameters at close range. This technology is widely used in high-precision measurement fields such as stealth technology research, high-performance radar antenna testing, satellite whole-satellite testing, and millimeter-wave antenna and system performance testing. The performance of the compact field is mainly evaluated by the flatness of the planar microwaves it forms, which requires calibration using a specialized testing system.

[0003] As a core component of the detection system, the compacted field scanning rig typically comprises four degrees of freedom: horizontal axis, vertical axis, feed axis, and polarization axis. Its performance indicators, such as travel range and positioning accuracy, depend on the quiet zone range and operating bandwidth of the compacted field under test. With the rapid development of stealth and anti-stealth technologies, as well as satellite technology, the demand for large quiet zone compacted fields is constantly increasing, leading to a corresponding increase in the demand for scanning rigs with large travel ranges and high positioning accuracy.

[0004] As the travel range of the scanning gantry increases, maintaining high positioning accuracy also becomes more challenging. Therefore, from a usability perspective, large compact scanning gantry designs often employ absolute position encoders (absolute optical encoders, absolute magnetic encoders, multi-turn absolute encoders, etc.) to eliminate the zero-finding problem caused by incremental encoder feedback. Considering the positioning accuracy of the compact scanning gantry, scanning gantry equipment often uses optical encoders or magnetic encoders to form a fully closed-loop feedback system to avoid errors caused by mechanical transmission backlash. However, limited by the register storage bits of the optical or magnetic encoder reading head, the maximum test range of an absolute optical encoder is generally no more than 20m, and the maximum test range of an absolute magnetic encoder is generally no more than 16m. For ultra-large compact scanning gantry equipment with a travel range exceeding 20 meters, only multi-turn absolute encoders or incremental magnetic encoders (optical encoders) can be used as feedback elements. Multi-turn absolute encoders use gear meshing with the motion shaft, which easily introduces transmission errors. Furthermore, large scanning frames often employ multi-segment support and splicing, making the feedback accuracy of multi-turn absolute encoders highly susceptible to the size of these joints. Especially when the equipment experiences temperature changes, significant deformation occurs in the travel direction, directly impacting feedback accuracy. Incremental magnetic scales (optical scales) cannot record the current absolute position; a zero-finding motion must be performed upon power-up to determine the position. For large scanning frames, zero-finding is too time-consuming and inconvenient to use.

[0005] The key problems in the existing technology are: for the needs of large stroke and high-precision position control of ultra-large compact field scanning frames of more than 20 meters, the single absolute magnetic grating ruler (grating ruler) solution cannot meet the stroke requirements; the position feedback accuracy of the multi-turn absolute encoder solution cannot meet the positioning accuracy requirements; and the incremental magnetic grating ruler (grating ruler) solution cannot meet the ease of use requirements. Summary of the Invention

[0006] The purpose of this invention is to provide a position feedback method for a scanning carriage to solve at least one of the problems existing in the prior art.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: The first aspect of the present invention provides a position feedback method for a scanning carriage, comprising: The motion controller receives control commands and sends control signals to the servo driver. The servo driver is used to send drive signals to the servo motor; A servo motor drives a horizontal motion module to move along the horizontal support frame of the scanning frame. The horizontal support frame includes n grids, adjacent grids have overlapping portions, and n-1 position calibration points are set in the n-1 overlapping portions. The horizontal motion module includes n reading heads corresponding to the n grids. The position data fed back by the (i-1)th grating ruler is read using the (i-1)th reading head and fed back to the motion controller via the encoder reading module. <i≤n; The motion controller sends a switching signal to the horizontal motion module, so that the horizontal motion module switches the i-th reading head to read the position data fed back by the i-th scale at the (i-1)-th position calibration point.

[0008] Optionally, the grating ruler is a magnetic grating ruler or an optical grating ruler.

[0009] Optionally, the method includes: The number of rulers is calculated based on the travel range of the horizontal axis of the horizontal support frame, the maximum test range of the ruler, and the range of the overlapping part.

[0010] Optionally, the formula for calculating the number of grid rulers based on the travel range of the horizontal axis of the horizontal support frame, the maximum test range of the grid ruler, and the range of the overlapping portion is as follows:

[0011] In the formula, The number of grating rulers; This refers to the travel range of the horizontal axis; This represents the maximum test range of the grating ruler; The range of the overlapping portion; This is the floor function.

[0012] Optionally, the range of the overlapping portion is less than or equal to 1 meter.

[0013] Optionally, the travel range of the horizontal axis is greater than 20 meters.

[0014] Optionally, the method includes: The horizontal support frame of the scanning rig is leveled using a laser tracker.

[0015] Optionally, the method includes: Each location calibration point is calibrated using a laser tracker.

[0016] Optionally, the switching period of the switching signal is less than 50 μs.

[0017] Optionally, the method further includes: The speed signal of the servo motor is fed back to the servo driver.

[0018] The beneficial effects of this invention are as follows: The technical solution described in this invention provides a high-precision position feedback method for ultra-large scanning rigs, aiming to achieve precise position control. It is not only applicable to the precise absolute position feedback of ultra-large compact field scanning rigs, but also widely applicable to ultra-large antenna scanning rigs, CNC machine tools, and other automated equipment that require high positioning accuracy for linear or circular motion. This achieves full closed-loop feedback of absolute position over a large stroke, while ensuring high positioning accuracy and ease of operation. Attached Figure Description

[0019] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0020] Figure 1 A flowchart of a position feedback method for a scanning frame provided by an embodiment of the present invention is shown.

[0021] Figure 2 This diagram illustrates a compacted-field scanning frame for a position feedback method for a scanning frame provided in an embodiment of the present invention.

[0022] Figure 3 This diagram illustrates the horizontal axis feedback arrangement of the scanning carriage for the position feedback method provided in an embodiment of the present invention.

[0023] Figure 4 This diagram illustrates the horizontal axis support frame and motion module for the position feedback method of the scanning gantry provided in an embodiment of the present invention.

[0024] Figure 5The large - stroke scanning frame feedback principle block diagram showing the position feedback method for a scanning frame provided by an embodiment of the present invention is shown. Detailed implementation manners

[0025] To more clearly illustrate the present invention, the present invention will be further described below in conjunction with embodiments and the accompanying drawings. Similar components in the drawings are denoted by the same reference numerals. Those skilled in the art should understand that the content specifically described below is illustrative rather than restrictive, and should not limit the protection scope of the present invention.

[0026] The key problems existing in the prior art are as follows: For the requirements of large - stroke and high - precision position control of ultra - large compact range scanning frames over 20 meters, in the single absolute magnetic scale (raster scale) scheme, the scale stroke range cannot meet the stroke requirements; in the multi - turn absolute encoder scheme, the position feedback accuracy does not meet the positioning accuracy requirements; in the incremental magnetic scale (raster scale) scheme, it does not meet the requirement of convenient use.

[0027] In view of this, as Figure 1 shown, an embodiment of the present invention provides a position feedback method for a scanning frame, including: using a motion controller to receive a control instruction and send a control signal to a servo driver; using the servo driver to send a drive signal to a servo motor; using the servo motor to drive a horizontal motion module to move along the horizontal support frame of the scanning frame, the horizontal support frame includes n scales, adjacent scales have overlapping parts, n - 1 position calibration points are arranged in n - 1 overlapping parts, and the horizontal motion module includes n reading heads corresponding to the n scales; using the (i - 1)th reading head to read the position data fed back by the (i - 1)th scale and feed it back to the motion controller through an encoder reading module, 1 < i ≤ n; using the motion controller to send a switching signal to the horizontal motion module so that the horizontal motion module switches to the i - th reading head to read the position data fed back by the i - th scale at the (i - 1)th position calibration point.

[0028] In a specific example, by reasonably arranging the absolute magnetic scale (or raster scale), through the reading and calculation of multi - path position feedback, the absolute position full - closed - loop feedback of the ultra - large - stroke compact range scanning frame is realized. This method not only breaks through the maximum test distance limit of a single absolute magnetic scale (or raster scale), but also provides higher positioning accuracy and more convenient use and maintenance compared with the feedback methods of multi - turn absolute encoders and incremental magnetic scales (raster scales). It can not only achieve full - closed - loop control to ensure positioning accuracy, but also read the current absolute position of the device, which is convenient to use; it can realize the real - time feedback of the absolute position of the large - stroke scanning frame, with convenient operation and high positioning accuracy.

[0029] In a specific example, as Figure 2The diagram shows a typical large-scale compact field scanning frame, which generally includes four degrees of freedom: horizontal axis, vertical axis, feed axis, and polarization axis. Its main structure consists of a horizontal support frame 1, a horizontal motion module 2, a vertical support frame 3, a vertical motion module 4, a feed compensation module 5, and a polarization turntable 6. The feed and polarization axes of the compact field scanning frame can use traditional feedback schemes. When the travel range of the horizontal and vertical axes exceeds the maximum testing range of the absolute magnetic grating scale (or optical grating scale), the feedback scheme proposed in this example can be considered.

[0030] In one possible implementation, the grating ruler is a magnetic grating ruler or an optical grating ruler.

[0031] In a specific example, taking the horizontal axis of an ultra-large compact field scanning frame as an example, the selection, arrangement, and position calculation method of the feedback device are as follows: A schematic diagram of the feedback arrangement of the horizontal axis of the compact field scanning frame is shown below. Figure 3 As shown. The horizontal axis uses an absolute magnetic grating ruler (or optical grating ruler) as position feedback, forming a fully closed-loop control system.

[0032] In a specific example, such as Figure 3 As shown, if a point is selected as the position calibration point within the overlapping area of ​​the grating ruler 8, then there are a total of n-1 position calibration points throughout the entire travel, namely a1, a2, ..., a (n-1) .

[0033] In a specific example, such as Figure 3 As shown, it includes the first grid ruler l1, the second grid ruler l2, the third grid ruler l3, ..., the nth grid ruler l n .according to Figure 3 The arrangement of the grating rulers 8 shown indicates that during the horizontal movement of the compact field scanning frame, at least one grating ruler reading head 7 can read the absolute position signal fed back by the corresponding grating ruler 8, thereby determining the current absolute position of the horizontal axis.

[0034] In one possible implementation, the method includes: calculating the number of grid rulers based on the travel range of the horizontal axis of the horizontal support frame, the maximum test range of the grid rulers, and the range of the overlapping portion.

[0035] In one possible implementation, the method further includes: feeding back the speed signal of the servo motor to the servo driver.

[0036] In a specific example, because the horizontal axis travel range of the compact field scanning frame is greater than the maximum feedback range of a single grating, multiple grating segments are spliced ​​together to achieve full coverage of the travel range. To ensure continuous and uninterrupted feedback, there is an overlapping area between adjacent gratings at both ends.

[0037] In a specific example, such as Figure 4 and Figure 5As shown, the absolute magnetic scale (or optical scale) consists of two parts: a scale 8 and a scale reading head 7. The scale 8 feeds back the absolute position data of the horizontal axis, and the scale reading head 7 reads the absolute position data and feeds it back to the motion controller. The scale 8 is mounted on the horizontal support frame 1, and the scale reading head 7 is mounted on the horizontal motion module 2. Each scale 8 corresponds to one scale reading head 7. During the movement of the horizontal motion module 2 along the horizontal support frame 1, the scale reading head 7 reads the position data fed back by the corresponding scale 8 and feeds it back to the motion controller through the encoder reading module.

[0038] In a specific example, the grid ruler 8 is installed on the horizontal support frame 1, and the grid ruler mounting groove is designed and processed in advance on the horizontal support frame 1.

[0039] In a specific example, each absolute magnetic grating ruler (or optical grating ruler) 8 is attached to the grating ruler mounting slot in the middle of the horizontal support frame 1.

[0040] In a specific example, the scale reading head 7 is mounted on the horizontal motion unit (horizontal motion module) 2.

[0041] In a specific example, there are n sets of grating ruler 8 and grating ruler reading head 7, and they correspond one-to-one.

[0042] In a specific example, the absolute position signal fed back by the grating ruler 8 is transmitted to the encoder reading module through the grating ruler reading head 7.

[0043] In a specific example, the encoder readout module transmits the absolute position signal to the motion controller via the EtherCAT bus.

[0044] In a specific example, the motion controller has a position processing unit that is responsible for receiving n absolute position signals fed back by the encoder reading module.

[0045] In a specific example, when the horizontal motion unit 2 moves through its full stroke, at least one set of scales 8 and scale reading heads 7 can provide feedback on the current absolute position of the horizontal axis.

[0046] In a specific example, the grid ruler 7 has n-1 overlapping regions.

[0047] In a specific example, in the non-overlapping region, the scanning gantry motion controller uses the current scale data as the position feedback source to form a fully closed-loop control.

[0048] In a specific example, in the overlapping area, when the horizontal motion unit crosses the position calibration point, the position processing unit inside the motion controller 10 will switch the feedback source in a timely manner to ensure the continuity of the servo motion.

[0049] In one possible implementation, the formula for calculating the number of grid rulers based on the travel range of the horizontal axis of the horizontal support frame, the maximum test range of the grid ruler, and the range of the overlapping portion is as follows:

[0050] In the formula, The number of grating rulers; This refers to the travel range of the horizontal axis; This represents the maximum test range of the grating ruler; The range of the overlapping portion; This is the floor function.

[0051] In a specific example, since the travel range may exceed the maximum feedback range of a single grating, multiple grating segments are spliced ​​together, and overlapping areas are set to ensure the continuity of feedback.

[0052] In one possible implementation, the range of the overlapping portion is less than or equal to 1 meter.

[0053] In one possible implementation, the travel range of the horizontal axis is greater than 20 meters.

[0054] In one possible implementation, the method includes leveling the horizontal support frame of the scanning gantry using a laser tracker.

[0055] In a specific example, the horizontal support frame 1 of the compact field scanning frame is mounted on the support pad 11, and the horizontal support frame 1 of the compact field scanning frame is leveled using a laser tracker.

[0056] In one possible implementation, the method includes calibrating each location calibration point using a laser tracker.

[0057] In a specific example, a laser tracker is used to calibrate each location point (a1, a2, ..., a...). (n-1) The calibration is performed to determine the absolute position value of the scanning frame corresponding to the point, and then marked in the position register of the motion controller. The calibration point is both the feedback end point of the previous section of the grating and the feedback start point of the next section of the grating.

[0058] In a specific example, when the horizontal motion module 2 of the scanning frame moves to the overlapping area of ​​the grid rulers 8, the motion controller can simultaneously read the absolute position information of the two grid rulers 8, and after calibration by the laser tracker, the feedback data of the two grid rulers 8 are consistent.

[0059] In a specific example, a position calibration point is selected in the overlapping area of ​​the grating ruler 7, and a laser tracker is used to calibrate each position calibration point to ensure that the two grating ruler reading heads 7 at the overlapping point can read the same absolute position signal.

[0060] In one possible implementation, the switching period of the switching signal is less than 50 μs.

[0061] In a specific example, the motion controller has a position processing unit inside, which is specifically used to receive multiple position signals fed back by the grating ruler 8 and to complete the timely switching of the position feedback source. That is, when the horizontal motion module 2 of the scanning frame moves to the calibration point of the overlapping area of ​​the grating ruler 8, the position processing unit of the motion controller promptly switches the feedback source of the position closed loop of the control system from the current feedback grating ruler to the next grating ruler. The switching cycle is within 50μs to ensure the continuity of servo motion.

[0062] In a specific example, the compact field scanning carriage completes n-1 signal source switching throughout its horizontal axis travel, enabling absolute position feedback throughout the entire horizontal axis travel of the scanning carriage.

[0063] In summary, this invention employs a multi-segment absolute magnetic grating ruler (or optical grating ruler) splicing technology, effectively overcoming the limitation of the maximum testing distance of a single grating ruler, and providing high-precision absolute position feedback for ultra-large stroke equipment exceeding 20 meters. This invention designs a dedicated position processing unit capable of receiving and processing multiple position feedback signals in real time, and achieving seamless switching between position feedback signal sources, ensuring the continuity and stability of position control. The method proposed in this invention is characterized by its simplicity, low cost, and strong versatility, and is suitable for various ultra-large automated equipment requiring high positioning accuracy for linear or circular motion.

[0064] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A position feedback method for a scanning carriage, characterized in that, include: The motion controller receives control commands and sends control signals to the servo driver. The servo driver is used to send drive signals to the servo motor; A servo motor drives a horizontal motion module to move along the horizontal support frame of the scanning frame. The horizontal support frame includes n grids, adjacent grids have overlapping portions, and n-1 position calibration points are set in the n-1 overlapping portions. The horizontal motion module includes n reading heads corresponding to the n grids. The position data fed back by the (i-1)th grating ruler is read using the (i-1)th reading head and fed back to the motion controller via the encoder reading module. <i≤n; The motion controller sends a switching signal to the horizontal motion module, so that the horizontal motion module switches the i-th reading head to read the position data fed back by the i-th scale at the (i-1)-th position calibration point.

2. The position feedback method for a scanning carriage according to claim 1, characterized in that, The grating ruler is a magnetic grating ruler or an optical grating ruler.

3. The position feedback method for a scanning carriage according to claim 2, characterized in that, The method includes: The number of rulers is calculated based on the travel range of the horizontal axis of the horizontal support frame, the maximum test range of the ruler, and the range of the overlapping part.

4. The position feedback method for a scanning carriage according to claim 3, characterized in that, The formula for calculating the number of gratings based on the travel range of the horizontal axis of the horizontal support frame, the maximum test range of the grating, and the range of the overlapping part is as follows: In the formula, The number of grating rulers; This refers to the travel range of the horizontal axis. This represents the maximum test range of the scale. The range of the overlapping portion; This is the floor function.

5. The position feedback method for a scanning carriage according to claim 4, characterized in that, The range of the overlapping portion is less than or equal to 1 meter.

6. The position feedback method for a scanning carriage according to claim 5, characterized in that, The travel range of the horizontal axis is greater than 20 meters.

7. The position feedback method for a scanning carriage according to claim 6, characterized in that, The method includes: The horizontal support frame of the scanning rig is leveled using a laser tracker.

8. The position feedback method for a scanning gantry according to claim 7, characterized in that, The method includes: Each location calibration point is calibrated using a laser tracker.

9. The position feedback method for a scanning gantry according to claim 8, characterized in that, The switching period of the switching signal is less than 50μs.

10. The position feedback method for a scanning gantry according to claim 9, characterized in that, The method also includes: The speed signal of the servo motor is fed back to the servo driver.

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