Absolute position synchronous pulse output method and system for a servo turntable

Abstract

The application discloses a kind of absolute position synchronous pulse output method and system of servo rotary table, belong to servo control technical field, method includes the same absolute position data source is applied to servo closed loop control and trigger pulse generation simultaneously, the absolute position data of end encoder is collected by servo controller, and based on the data driving servo mechanism action, the physical displacement pulse of the servo mechanism is monitored in real time by pulse trigger module, and according to the preset pulse interval parameter, synchronous trigger signal is generated by the way of interrupt counting, and the synchronous trigger signal is output to external test equipment after level conversion processing, the present application uses hardware interrupt counting to replace traditional software polling comparison, realizes microsecond level real-time response, and only single encoder can be completed control and trigger, greatly reduce hardware cost, applicable to antenna test and radar scanning system.

Description

Technical Field

[0001] This invention relates to the field of servo control technology, specifically to a method and system for synchronizing the absolute position pulse of a servo turntable. Background Technology

[0002] In high-precision radio frequency testing (such as antenna far-field / near-field testing) or radar scanning systems, servo turntables not only need to drive the load (such as an antenna) to make precise attitude adjustments, but also need to output synchronization pulse signals at specific rotation angle positions to trigger devices such as vector network analyzers and spectrum analyzers to complete data acquisition. This requires the turntable's mechanical position and the output trigger pulse to have extremely high synchronization accuracy and real-time performance.

[0003] In existing technologies, the above functions are mainly achieved using the following two schemes. Scheme 1: A soft comparison trigger scheme based on a high-performance motion controller. This scheme utilizes the motion controller to periodically read the position data of the end absolute encoder and compare it with the preset target position in software. When the target value is reached, a trigger pulse is output. However, since the encoder usually uses bus communication (such as EtherCAT, Profinet), and the scanning cycle of the motion controller is usually in the millisecond range, there is an unavoidable delay in position reading, logic judgment, and pulse output. When the turntable is moving at high speed, the output trigger pulse will produce a significant hysteresis error with the actual physical position, making it difficult to meet the synchronization requirements of high-precision testing. In addition, multi-axis motion controllers with high real-time performance are expensive.

[0004] Option 2: Hardware triggering scheme based on dual encoders; To address the delay issue, some schemes employ a coaxial dual encoder structure: one absolute multi-turn encoder for servo closed-loop control (no need for homing), and another incremental encoder specifically for acquiring pulses to generate trigger signals. While this scheme improves real-time performance to some extent, the need for two independent encoders and their mounting structures leads to a complex mechanical structure, large size, and a significant increase in hardware costs.

[0005] In summary, existing servo turntable triggering schemes generally suffer from poor real-time performance or high costs, and there is an urgent need for a method that is simple in structure, low in cost, and can guarantee high real-time synchronous pulse output. Summary of the Invention

[0006] The purpose of this section is to outline some aspects of the embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0007] Therefore, the purpose of this invention is to provide a method and system for servo turntable absolute position synchronization pulse output, so as to solve the problems mentioned in the background art.

[0008] To address the aforementioned technical problems, according to one aspect of the present invention, the present invention provides the following technical solution:

[0009] A method for outputting absolute position synchronization pulses for a servo turntable, comprising the following steps:

[0010] S1. Apply the same absolute position data source to both servo closed-loop control and trigger pulse generation simultaneously;

[0011] S2. Acquire the absolute position data of the end encoder through the servo controller, and drive the servo mechanism to move based on the data;

[0012] S3. The physical displacement pulse of the servo mechanism is monitored in real time by the pulse trigger module, and a synchronous trigger signal is generated by interrupt counting according to the preset pulse interval parameter.

[0013] S4. The synchronous trigger signal is processed by level conversion and then output to an external test device.

[0014] As a preferred embodiment of the servo turntable absolute position synchronization pulse output method of the present invention, the servo turntable includes an azimuth axis and a pitch axis, and the servo turntable absolute position synchronization pulse output method further includes:

[0015] A data gear is provided on the drive chain of the azimuth axis and / or pitch axis, and the data gear is provided with a through hole structure for being identified by a photoelectric detection sensor;

[0016] The pulse triggering module acquires the physical displacement by collecting the pulse signal output by the photoelectric detection sensor.

[0017] In a preferred embodiment of the servo turntable absolute position synchronization pulse output method described in this invention, the gear ratio z of the data gear is 1:2. n , where n is a positive integer used to improve the resolution of the trigger pulse.

[0018] In a preferred embodiment of the servo turntable absolute position synchronization pulse output method of the present invention, the pulse triggering module and the servo controller interact with each other via a serial communication interface.

[0019] The servo controller sends trigger start / stop commands and pulse interval parameters to the pulse trigger module. ;

[0020] The pulse triggering module transmits the current working status information back to the servo controller in real time.

[0021] In a preferred embodiment of the servo turntable absolute position synchronization pulse output method described in this invention, the pulse trigger module has a built-in counter that detects the number M of pulses generated by the photoelectric sensor via an interrupt method, and sets a threshold n of the number of encoder pulses required to output one trigger pulse. x When M=n is detected x When the x-th trigger pulse is output, the x-th trigger pulse is output.

[0022] As a preferred embodiment of the servo turntable absolute position synchronization pulse output method described in this invention, the encoder pulse number threshold n x The calculation formula is:

[0023] ;

[0024] Where x is the output pulse number, The preset pulse interval angle, denoted by , where z is the encoder line count and z is the gear ratio of the data gear.

[0025] In a preferred embodiment of the servo turntable absolute position synchronization pulse output method described in this invention, the pulse width of the synchronization trigger signal is set by software configuration within the pulse trigger module, and the amplitude of the synchronization trigger signal is adjusted by adjusting the external power supply voltage VCC of the level conversion circuit.

[0026] As a preferred embodiment of the servo turntable absolute position synchronization pulse output method described in this invention, the servo controller adopts an FPGA and the pulse triggering module adopts an STM32 series microcontroller.

[0027] A servo turntable absolute position synchronization pulse output system, comprising:

[0028] The servo controller is used to acquire the absolute position data of the end encoder and perform servo closed-loop control.

[0029] The pulse triggering module is communicatively connected to the servo controller and is used to receive pulse interval parameters and acquire physical displacement pulses through an interrupt method to generate a synchronous trigger signal.

[0030] A photoelectric detection component is installed on the turntable transmission mechanism side to collect physical displacement pulses and send them to the pulse triggering module;

[0031] A level conversion circuit is used to convert the signal output by the pulse trigger module into a level signal that meets the requirements of external devices.

[0032] As a preferred embodiment of the servo turntable absolute position synchronous pulse output system described in this invention, the servo controller acquires the absolute position data of the absolute multi-turn encoder through the Profinet bus protocol, and the servo controller and the pulse trigger module exchange data through an RS422 serial port.

[0033] Compared with the prior art, the beneficial effects of the present invention are:

[0034] 1. This invention breaks through the serial link delay of controller read-calculation-output in traditional solutions. By directly using the position information of the absolute encoder for servo control, and simultaneously utilizing the pulse trigger module to count interrupts of physical displacement pulses, a microsecond-level response speed is achieved. The pulse output is directly triggered by hardware interrupts, unaffected by bus communication cycles and the computational load of the main controller, ensuring strict synchronization between the trigger pulse and the physical position of the turntable, making it particularly suitable for high-speed motion scenarios.

[0035] 2. This invention requires only one absolute multi-turn encoder to simultaneously achieve servo closed-loop control and trigger pulse generation, completely eliminating the need for traditional dual-encoder solutions. The trigger core can be implemented using a low-cost microcontroller such as STM32, eliminating the need for an expensive high-performance motion controller. Furthermore, by optimizing the data gear ratio, the machining and assembly difficulties are simplified while maintaining accuracy, significantly reducing the overall hardware cost of the system.

[0036] 3. This invention decouples pulse parameters from hardware. The pulse width can be flexibly adjusted via software configuration without modifying the circuit; the amplitude can be adjusted via the power supply voltage of the level conversion circuit. This allows the output trigger signal to be easily adapted to test equipment from different manufacturers, exhibiting strong versatility and compatibility. The control logic of this solution is independent of the number of axes, and can be easily extended to multi-axis synchronous triggering scenarios such as azimuth and pitch. Because the pulse trigger module operates independently and does not interfere with the main servo control loop, the system operates more stably and reliably, and the real-time performance of servo control will not be affected by the busy triggering task. Attached Figure Description

[0037] To more clearly illustrate the technical solutions of the embodiments of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and detailed embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0038] Figure 1 This is a schematic diagram of the servo turntable absolute position synchronization pulse output system provided by the present invention.

[0039] Figure 2The schematic diagram of the mechanical transmission and data gear installation principle of the servo turntable provided by the present invention;

[0040] Figure 3 The hardware circuit principle block diagram of the pulse triggering module provided by the present invention;

[0041] Figure 4 The software execution flowchart of the pulse triggering module provided by the present invention is shown. Detailed Implementation

[0042] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0043] like Figure 1 As shown, the servo turntable absolute position synchronous pulse output system of the present invention mainly consists of a host computer, a servo controller, a pulse triggering module, a servo driver, a transmission mechanism, and an encoder. The host computer interacts with the servo controller through a network port or serial port, and sends target position and start / stop commands. The servo controller, as the core control terminal, uses an FPGA chip internally to collect the absolute position data of the end encoder, execute an improved PID algorithm, and output speed commands to the servo driver. At the same time, the servo controller communicates with the pulse triggering module (which uses an STM32 series microcontroller as its core) through an RS422 serial port, and sends pulse interval parameters Δa and start / stop commands.

[0044] like Figure 2 and Figure 3 As shown, in order to achieve high-precision position triggering without adding an additional high-precision encoder, the mechanical structure of this invention has been optimized.

[0045] The azimuth and pitch axes of the turntable are equipped with absolute multi-turn encoders, and the position data is uploaded to the servo controller via the Profinet bus.

[0046] Meanwhile, a data gear 6 is installed on the transmission chain. Taking the azimuth axis as an example, the motor 1 drives the load to rotate through the reduction mechanism 2, transmission gears 3 and 4. The data gear 6 is designed with a through hole, and the pulse signal generated by the through hole is detected by the azimuth photoelectric detection sensor.

[0047] Specifically, in this embodiment, the data gear ratio is configured as z=1:2n (preferably n=1, i.e., 1:2). This design ensures that the number of encoder lines and the number of gear teeth are integer multiples of each other, greatly simplifying the calculation complexity of subsequent pulse triggering and improving accuracy.

[0048] like Figure 3As shown, the hardware circuit of the pulse trigger module includes an optocoupler isolation unit, an STM32 main control unit, and a level conversion unit. The pulse signal output by the photoelectric sensor is input to the STM32's I / O port after optocoupler isolation. The STM32 receives instructions from the servo controller via the RS422 interface. When the STM32 determines that the trigger position has been reached, it outputs a TTL level pulse. This pulse is processed by the level conversion circuit and finally output to test equipment such as vector network analyzers. The amplitude of the pulse can be adjusted by changing the power supply VCC of the level conversion circuit, while the pulse width is adjustable in software through the STM32's internal timer configuration.

[0049] like Figure 4 As shown, the software execution flow of the pulse triggering module is as follows:

[0050] S1. Initialization: After the system is powered on, initialize the GPIO ports, serial ports and interrupt configurations.

[0051] S2, Command Reception: Waiting to receive commands from the servo controller, including the start bit (st), stop bit (stp), and pulse interval angle. .

[0052] S3. Parameter Calculation: When the start bit st=1, the system performs pre-calculation according to the following formula, setting the encoder line count to... Given a data gear ratio of z, calculate the encoder pulse threshold required to output the x-th pulse. .

[0053] S4. Interrupt Count: Enable external interrupts to monitor the physical pulses generated by the photoelectric switch in real time and accumulate the pulse count M.

[0054] S5. Comparison Output: When the cumulative pulse count M is equal to the set threshold n1, the first trigger pulse is output; when M=n2, the second trigger pulse is output, and so on.

[0055] S6. Loop and Stop: The module continuously performs interrupt detection and comparison until it receives a stop command stp=1. At this time, the system clears all parameters and returns to the waiting state.

[0056] Although the present invention has been described above with reference to embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the invention. In particular, as long as there is no structural conflict, the features in the disclosed embodiments can be combined with each other in any manner. The lack of an exhaustive description of these combinations in this specification is merely for the sake of brevity and resource conservation. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for outputting absolute position synchronization pulses for a servo turntable, characterized in that the steps include... include: S1. Apply the same absolute position data source to both servo closed-loop control and trigger pulse generation simultaneously; S2. Acquire the absolute position data of the end encoder through the servo controller, and drive the servo mechanism to move based on the data; S3. The physical displacement pulse of the servo mechanism is monitored in real time by the pulse trigger module, and a synchronous trigger signal is generated by interrupt counting according to the preset pulse interval parameter. S4. The synchronous trigger signal is processed by level conversion and then output to an external test device.

2. The method for outputting absolute position synchronization pulses of a servo turntable according to claim 1, characterized in that, The servo turntable includes an azimuth axis and a pitch axis, and the method for outputting the absolute position synchronization pulse of the servo turntable further includes: A data gear is provided on the drive train of the azimuth axis and / or pitch axis, and the data gear is provided with a through hole structure for being identified by a photoelectric detection sensor; The pulse triggering module acquires the physical displacement by collecting the pulse signal output by the photoelectric detection sensor.

3. The method for outputting absolute position synchronization pulses of a servo turntable according to claim 2, characterized in that, The gear ratio z of the data gear is 1:2 n , where n is a positive integer used to improve the resolution of the trigger pulse.

4. The method for outputting absolute position synchronization pulses of a servo turntable according to claim 1, characterized in that, The pulse triggering module and the servo controller interact with each other via a serial communication interface. The servo controller sends trigger start / stop commands and pulse interval parameters to the pulse trigger module. ; The pulse triggering module transmits the current working status information back to the servo controller in real time.

5. The method for outputting absolute position synchronization pulses of a servo turntable according to claim 2, characterized in that, The pulse triggering module has a built-in counter that detects the number of pulses M generated by the photoelectric sensor via an interrupt method, and sets a threshold n of the number of encoder pulses required to output one trigger pulse. x When M=n is detected x When the x-th trigger pulse is output, the x-th trigger pulse is output.

6. The method for outputting absolute position synchronization pulses of a servo turntable according to claim 5, characterized in that, The encoder pulse number threshold n x The calculation formula is: ； Where x is the output pulse number, The preset pulse interval angle, denoted by , where z is the encoder line count and z is the gear ratio of the data gear.

7. The method for outputting absolute position synchronization pulses of a servo turntable according to claim 1, characterized in that, The pulse width of the synchronous trigger signal is set by the software configuration within the pulse trigger module, and the amplitude of the synchronous trigger signal is adjusted by adjusting the external power supply voltage VCC of the level conversion circuit.

8. The method for outputting absolute position synchronization pulses of a servo turntable according to claim 1, characterized in that, The servo controller uses an FPGA, and the pulse triggering module uses an STM32 series microcontroller.

9. A servo turntable absolute position synchronization pulse output system, used to implement the servo turntable absolute position synchronization pulse output method according to any one of claims 1 to 8, characterized in that, include: The servo controller is used to acquire the absolute position data of the end encoder and perform servo closed-loop control. The pulse triggering module is communicatively connected to the servo controller and is used to receive pulse interval parameters and acquire physical displacement pulses through an interrupt method to generate a synchronous trigger signal. A photoelectric detection component is installed on the turntable transmission mechanism side to collect physical displacement pulses and send them to the pulse triggering module; A level conversion circuit is used to convert the signal output by the pulse trigger module into a level signal that meets the requirements of external devices.

10. A servo turntable absolute position synchronization pulse output system according to claim 9, characterized in that, The servo controller acquires the absolute position data of the absolute multi-turn encoder through the Profinet bus protocol, and the servo controller and the pulse trigger module exchange data through an RS422 serial port.

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