Retractable reconfigurable antenna servo control system and control method thereof

Abstract

The invention provides a retractable reconfigurable antenna servo control system and a control method thereof, the system comprises a servo control module, a servo driving module, a motor, a lead screw, a limit switch and a power supply module, the servo control module is used for receiving a control instruction and outputting a control signal; the servo driving module drives the motor to drive the lead screw to move according to the control signal, so as to drive the retractable reconfigurable antenna to finish retracting and releasing actions; the limit switch is used for limiting the retractable position of the retractable reconfigurable antenna and feeding back a feedback signal to the servo control module; the power supply module is used for providing multi-path power supply output for the servo control system; wherein the servo control module adopts a double-closed-loop control strategy including a current closed loop and a speed closed loop, realizes accurate control on the current and the rotating speed of a motor, and judges whether the retractable reconfigurable antenna moves to a preset position or not based on a feedback signal of a limit switch. The system is high in integration level and compatibility, and solves the problem that the installation part on an airplane is narrow and limited.

Description

Technical Field

[0001] This invention relates to the field of antenna technology, and in particular to a retractable reconfigurable antenna servo control system and its control method. Background Technology

[0002] Antennas are the most basic building blocks for signal transmission and reception in various aircraft. Most existing antennas are installed and fixed by welding, and some aircraft that need to cover a wide area of ​​signal coverage even need to install more than one antenna. For existing civilian and commercial drones and other aircraft, the available space is very limited. Installing multiple antennas not only restricts the structure, but also causes electromagnetic interference problems caused by the close proximity of the antennas.

[0003] In addition, even if some existing antennas can achieve telescopic functionality, they use a simple telescopic rod principle. After long-term use, the gaps between the antenna sections will increase, causing them to loosen and thus the antenna to retract. Alternatively, antenna telescopic functionality can be achieved by using antenna extension and retraction devices with motors, propellers, and buffer mechanisms. This method changes the appearance and structure of the aircraft, requires disassembly and assembly, and is inconvenient to carry and store.

[0004] In related technologies, CN212380544U discloses a retractable antenna for UAVs. Its working principle is that a telescopic mechanism is fixedly protruding from one side of the upper surface of the frame. The upper end of the telescopic mechanism is connected to the antenna body. Buffer mechanisms are installed and connected at the four corners of the bottom surface of the frame. The lower end of the antenna body is inserted into the groove in the middle of the square column of the telescopic mechanism, which can realize the telescopic function of the antenna.

[0005] CN212783777U discloses an automatic retraction and extension device for a multi-rotor UAV antenna. Its working principle is to achieve automatic retraction and extension through a forward and reverse motor, a first rotating shaft, and a first and second gear. The forward and reverse motors are rotated by a control switch, which drives the first and third rotating shafts to rotate, and then drives the second gear to rotate. Under the mutual meshing between the gears, the fixed tube is moved and extended more quickly.

[0006] Most existing technologies employ multiple antennas mounted simultaneously on the aircraft surface to achieve wide-angle scanning without damaging the mechanical structure and strength of the drone's surface. However, the large number and close spacing of the antennas lead to increased costs and electromagnetic interference between them. Alternatively, the two types of retractable antennas mentioned above can be used to transmit and receive multiple frequency bands by adjusting the height of the antenna body. However, the entire telescopic mechanism and external buffer mechanism are exposed to the outside of the aircraft, resulting in poor surface flatness, space occupation, or the need for disassembly and reassembly, leading to unsatisfactory deployment and retraction performance. Summary of the Invention

[0007] The technical problem to be solved by this invention is how to achieve a reasonable design of aircraft antennas. This invention proposes a retractable reconfigurable antenna servo control system and its control method.

[0008] According to an embodiment of the present invention, a retractable reconfigurable antenna servo control system is provided, wherein the retractable reconfigurable antenna is mounted on an aircraft, and the servo control system is used to control the retraction and extension movements of the retractable reconfigurable antenna. When the retractable reconfigurable antenna is in operation, it extends out of the aircraft surface; when operation is terminated, it retracts into the aircraft body, conforming to the outer surface of the aircraft. The servo control system includes: The servo control module is used to receive control commands and output control signals; A servo drive module, connected to the servo control module, is used to drive the motor to move according to the control signal; An electric motor, connected to a lead screw, is used to drive the lead screw to move; The lead screw is connected to the retractable reconfigurable antenna and is used to drive the retractable reconfigurable antenna to complete the retraction and extension actions. Limit switches are used to limit the retraction and extension positions of the retractable reconfigurable antenna and to feed back the feedback signal to the servo control module. The power module is used to provide multiple power outputs for the servo control system. The servo control module employs a dual closed-loop control strategy, including a current closed loop and a speed closed loop, to achieve precise control of the motor current and speed. Based on the feedback signal from the limit switch, it determines whether the retractable reconfigurable antenna has moved to a preset position.

[0009] According to some embodiments of the present invention, the power supply module includes: Reverse connection protection circuit, used for reverse connection protection; Overvoltage and overcurrent protection circuits are used for overvoltage and overcurrent protection. Differential-mode and common-mode filter circuits are used to suppress noise signals conducted along the power lines; Surge suppression circuit is used to control the peak value of the input inrush current within a preset current. The power module has an input voltage range of 18V to 32V DC and outputs multiple power supplies including +5V, +3.3V, +1.9V, and +12V.

[0010] In some embodiments of the present invention, the servo control module includes a digital signal processor for executing a PID control algorithm and communicating with an external system via an RS485 interface.

[0011] According to some embodiments of the present invention, the servo control module is also used to realize antenna status reporting, electronic tag management, health status monitoring and online upgrade functions.

[0012] In some embodiments of the present invention, the servo control module receives online upgrade commands via a serial port to complete remote updates of the control software.

[0013] According to some embodiments of the present invention, the servo drive module includes: The motor drive chip is used to generate motor drive signals and brake control signals based on the control signals received from the servo control module. Optical MOS relays are used to amplify and output brake control signals to control the switching of motor brakes. Hall effect current sensors are used to detect motor current and feed it back to the servo control module.

[0014] In some embodiments of the present invention, the motor is a brushless DC motor, and a Hall position sensor is installed inside the motor to provide speed feedback signals to the servo control module.

[0015] According to some embodiments of the present invention, the servo control system further includes a non-volatile memory for storing antenna operation logs, fault data, and upgrade programs.

[0016] The control method of the retractable reconfigurable antenna servo control system according to an embodiment of the present invention is characterized by comprising: S10, receive take-up and release control commands; S20 drives the motor to move the lead screw through a dual closed-loop control strategy; S30 detects the limit switch signal to determine whether the retractable reconfigurable antenna is in position; if it is in position, it controls the motor brake to lock the position of the retractable reconfigurable antenna. S40 reports antenna status and servo control system health information in real time.

[0017] According to some embodiments of the present invention, the method further includes: when the motor is stalled, limiting the motor current within a safe range through current closed-loop control to maintain the motor output torque.

[0018] The present invention has the following beneficial effects: The retractable reconfigurable antenna servo control system of the present invention is based on modular and miniaturized design, which reduces the number of antennas required, lowers costs, and greatly avoids electromagnetic interference between antennas. It solves the problem of limited installation space on aircraft. Moreover, the invention has high integration and strong compatibility, and can be widely used in antennas in different occasions. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the working principle of the servo control system according to an embodiment of the present invention; Figure 2 This is an overall design diagram of the power supply circuit of the servo control system according to an embodiment of the present invention; Figure 3 This is a design diagram for power input surge protection and reverse connection protection according to an embodiment of the present invention; Figure 4 This is a block diagram of a servo control circuit design according to an embodiment of the present invention; Figure 5 This is a block diagram of a servo drive circuit design according to an embodiment of the present invention; Figure 6 This is a circuit diagram of a detection voltage filter amplifier according to an embodiment of the present invention; Figure 7 This is a control flowchart of the servo control system according to an embodiment of the present invention; Figure 8 This is a schematic diagram of the servo control software flow according to an embodiment of the present invention; Figure 9 This is a block diagram of the functional components of servo control software according to an embodiment of the present invention. Detailed Implementation

[0020] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments.

[0021] The steps described in the specification and the flowcharts in the accompanying drawings of this invention are not necessarily to be strictly followed according to the step numbers; the execution order of the steps can be changed. Furthermore, certain steps can be omitted, multiple steps can be combined into one step, and / or one step can be broken down into multiple steps.

[0022] This invention designs a reconfigurable retractable antenna servo control system, which enables the antenna to replace multiple antennas to meet the requirements of wide-angle signal coverage, while not affecting the mechanical structure of the aircraft surface, and can ensure conformal integration with the aircraft surface when the antenna is retracted.

[0023] The retractable reconfigurable antenna servo control system designed in this invention adopts a dual closed-loop control strategy to precisely control the antenna's retraction and extension stroke. It has strong versatility and a high degree of automation, and can be applied to various space-constrained civilian drones, etc.

[0024] When the drone antenna needs to transmit and receive signals, it extends out of the aircraft's radome in a controlled manner to perform wide-angle signal scanning coverage over a large airspace. When the operation is finished, the antenna can be completely retracted into the aircraft in a controlled manner, achieving the effect of the antenna bottom cover conforming to the aircraft surface.

[0025] In addition, the servo control system can also perform functions such as reporting antenna status, reporting electronic logs, and completing online upgrades. It is more intelligent than traditional passive antennas. In special cases such as excessive motor current and stall, it can automatically compensate and adjust the output current in real time according to the dual closed-loop control, control the current to protect the motor, and avoid motor burnout, thereby improving the accuracy and reliability of antenna deployment and reception.

[0026] Specifically, the present invention employs the following hardware and software design to complete the retractable reconfigurable antenna servo control system: Hardware design of a retractable reconfigurable antenna servo control system: The servo control system consists of a servo control module, a servo drive module, a brushless DC motor, a lead screw, and upper / lower limit switches.

[0027] The servo control module and drive module are stacked to achieve signal interconnection. Together with the filter, they form a metal sealed box fixed to the antenna cover. The servo control module receives control commands through an asynchronous serial port and outputs PWM and motor direction signals to the servo drive module according to the DSP real-time algorithm. The servo drive module drives the motor to drive the lead screw to complete the antenna's extension and retraction. It also sends antenna status and self-test information to the low-frequency rack through the asynchronous serial port.

[0028] The servo control system employs the classic PID algorithm to achieve dual closed-loop control of current and speed. Current feedback utilizes a Hall effect current sensor, while speed feedback is calculated using the motor's built-in Hall effect position sensor. This dual closed-loop control allows for precise control of the motor's current and speed, making the antenna raising and lowering process safer and smoother. When the antenna retraction / extraction device touches the upper / lower limit switch, the motor stalls according to the program, presses the switch, and stops running, thus completing the antenna raising or lowering process. Its working principle is as follows: Figure 1 As shown.

[0029] Servo control system power conversion circuit design: The servo control system is powered by two DC +28V sources and is required to operate normally within a +18~32V range with a power consumption not exceeding 120W. The servo control system performs multiple processing steps on the input power supply front-end to improve its power supply compatibility and electromagnetic compatibility (such as reverse connection protection, overcurrent and overvoltage protection, common-mode and differential-mode filtering, and surge protection) before inputting it to the main isolated power supply. The main power supply of the servo control system uses a surge protector and has built-in input undervoltage protection and short-circuit protection. To meet the requirements of short-term high current surges in pulse trains, the power supply output is designed with large-capacity capacitors for energy storage and filtering. In addition, there are multiple auxiliary power supplies for different outputs. The overall design diagram is shown below. Figure 2 As shown.

[0030] Two 28V power supplies and a return line are input, each with a fuse for current limiting at the front end. Input surge protection and voltage spike absorption employ a two-stage suppression design. The first stage uses a varistor to absorb larger surge voltage pulses, while the subsequent stage uses a TVS diode to further absorb residual surge voltage pulses. The first and second stages are decoupled using an inductor for voltage pulse delay. The reverse connection protection circuit uses high-current Schottky diodes selected based on the power rating; during reverse connection, the main voltage drop occurs across these diodes. The schematic diagram is shown below. Figure 3 As shown.

[0031] The differential-mode and common-mode filter inductors and capacitors together form a two-stage differential-mode and common-mode filter, which can effectively suppress noise signals conducted along the power line and meet electromagnetic compatibility requirements. The surge current suppression circuit controls the peak input inrush current to within 5 times the rated current, and it consists of resistors, capacitors, Zener diodes, and MOSFETs. The surge protection input voltage range is 18~32VDC, and the output clamping voltage is 33VDC, which can protect the power supply against surge voltage, reverse polarity protection, and reverse current.

[0032] After processing the external input power supply in various ways, the main power supply and auxiliary power supply outputs are mainly divided into four paths: one path is converted by the power module to output +5V, then converted by the power chip HWD70302MAG to +3.3V and +1.9V required for DSP operation, and then generated by the ferrite bead to produce the required analog power supply. The +5V is also converted by the ferrite bead to produce an analog 5V power supply; one path supplies the driver chip WBC03GDM to drive the motor; one path is converted by the voltage regulator (G)CW7812Z to +12V to power the Hall sensor of the brushless motor; and one path supplies power to the brake.

[0033] Servo control system control circuit design: The main functions of the servo control board are: receiving control commands via RS485 asynchronous serial port; executing corresponding control algorithms based on the commands; outputting PWM signals, motor rotation direction control signals, and braking control signals to the servo drive board; detecting feedback signals from the motor Hall position sensor and current sensor to achieve closed-loop control of the servo control system; monitoring the status of the servo control subsystem; and transmitting operating status and fault information back to the low-frequency rack via RS485 asynchronous serial port. The control circuit design block diagram is shown below. Figure 4 As shown.

[0034] The servo control module uses a JDSPF28335 digital signal processor, which mainly performs important functions such as external communication, dual closed-loop parameter calculation, PWM signal driving, brake control, and analog-to-digital conversion. The NVRAM uses an SM14C88-3NF45, which serves as an extended memory for the DSP and realizes health management functions such as antenna electronic tag reporting and maintenance logs. Two SM3485 transceivers complete two-channel RS485 external communication functions. This device can achieve a transmission rate of up to 10Mbps, which meets the design requirements. The E2PROM device uses an SM9977, which allows the servo control system to save various data during the antenna retraction and extension process after power failure. The watchdog circuit uses an SM706T chip to monitor the system operating voltage and outputs a reset signal when the voltage is too low.

[0035] Servo control system drive circuit design: The servo drive module receives control signals from the servo control module to drive the Hall effect brushless motor and control the brake, while simultaneously feeding back motor current and speed information to the servo control module. The servo drive module uses the WBC03GDM driver chip to meet the drive design requirements; a JGW-3MG optical MOS relay is selected to amplify and output the motor braking signal, controlling the motor brake switch; a Hall effect current sensor HCS724A-05U is used for bus voltage isolation detection, and the current signal is conditioned and filtered to achieve closed-loop current control before being fed back to the servo control module. The drive circuit design block diagram is shown below. Figure 5 As shown.

[0036] Hall effect brushless DC motors are lightweight and compact. Given the limited space in the deployment and take-off mechanism, the system eliminates the need for additional speed or position sensors. The brushless motor can obtain its speed information through feedback signals from an internal Hall effect position sensor, achieving a closed-loop speed control system. Therefore, a Hall effect brushless DC motor is chosen as the actuator for the deployment and take-off antenna. Its bus detection voltage is amplified and low-pass filtered as follows... Figure 6 As shown.

[0037] The amplifier circuit is shown in equation (1): (1); Equation (2) is obtained: (2); From this, R1 and R2 can be derived. The filter circuit formulas are shown in equations (3) and (4). Based on a cutoff frequency of 500Hz, the values ​​of R and C can be derived: (3); Equation (4) is obtained: ; (4); Antenna take-off and retraction control design: Antenna deployment and retraction control is one of the most important functions of this system. After the antenna is lowered, the lead screw should extend to the specified length. After the antenna is retracted, it should maintain high precision in engagement with the machine body surface. To meet this performance requirement, the antenna should be precisely controlled to reach the specified position and remain stable after both deployment and retraction. The servo control system flowchart takes antenna retraction as an example. Figure 7 As shown.

[0038] During antenna retraction, the servo system uses a dual closed-loop control method to rapidly increase the brushless motor to its rated speed. When the antenna retracts and presses the upper limit switch, the reconfiguration mechanism reaches the mechanical limit and stops rising, and the motor begins to stall. Because the control system uses current closed-loop control, after the motor stalls, the output current of the control system rapidly increases and stabilizes to the threshold current (within the range of the motor's continuous stall current). The brushless motor maintains its torque output and continues to rise, keeping the reconfiguration mechanism in close contact with the mechanical limit, meeting the system's engagement gap requirements. Simultaneously, the controller outputs a command to engage the brake, locking the motor output shaft, locking the reconfiguration mechanism's position, and retracting the antenna to its final position. When the motor is stalled, as long as the current value is less than its continuous stall current value, the motor can operate stably under this condition. The servo control system uses a Hall current sensor to sample the bus current in real time, limiting the motor current to near a given value through the control current loop, thereby ensuring the reconfiguration mechanism executes its actions to the required position while maintaining equipment safety and reliability, meeting the system's engagement gap requirements. Since the antenna deployment position does not involve surface alignment, when the antenna touches the lower limit switch, the brake engages, and the antenna is deployed to the correct position.

[0039] Software design for a retractable reconfigurable antenna servo control system: (1) Servo control system software design: The core component of the servo control system is a digital signal processor (DSP). The software is written in C. Its main functions include receiving antenna transmission and reception control commands via serial port, online upgrades, antenna status reporting, and other auxiliary commands. The control system primarily controls the PWM and direction signals of the driver chip through I / O ports to drive the brushless motor in forward and reverse rotation. The DSP processor performs real-time speed calculations and current sampling, applying dual-closed-loop digital loop correction to achieve precise control of motor current and speed. It also transmits antenna status information, electronic tag data, and health management information back to the low-frequency rack. The software adopts a modular design, encapsulating different functional modules into functions, resulting in clear logic, high readability, and easy functional expansion. A flowchart of the servo control system software is shown below. Figure 8 As shown in the diagram, the functional components are as follows: Figure 9 As shown.

[0040] The servo control software calculates the speed from the Hall position sensor data of the brushless DC motor in real time and samples the current from the Hall current sensor. It performs dual closed-loop control of the system by processing the feedback signals of current and speed in real time. The software calculates the speed control signal every cycle, and these control signals are then corrected by digital PID to generate the PWM control signal for the motor. This motor control signal is amplified by the driver and drives the antenna to complete the specified actions. In addition, health management is a major component of the control software, including various status detection, fault status reporting, fault data processing, electronic tags, and log storage. This part of the functionality is relatively independent of the servo control function in the software, meeting the user's requirements for antenna status query and maintenance, self-test status reporting, and log storage.

[0041] (2) Software online loading design: The servo control software communicates with the outside world via an SCI asynchronous serial port with a communication baud rate of up to 3.125Mbps. After receiving an online upgrade request, the control software begins to receive upgrade code data frames, verifies each frame, and stores it in a non-volatile memory area after verification. After receiving all frame data sent by the system and verifying them, the software moves the code data received in the storage area to a fixed area of ​​the DSP's internal FLASH. After power-on, the DSP starts the newly loaded program from the fixed address of the DSP's internal FLASH through the boot loader address, thus completing the online upgrade function.

[0042] In summary, for small civilian and commercial aircraft with limited installation space, this invention offers a viable alternative to existing conformal antenna installation schemes that utilize multiple antennas in a single retractable antenna. This approach achieves the signal coverage of multiple antennas in a single generation, significantly reducing electromagnetic interference issues caused by an excessive number of antennas and effectively controlling costs. The antenna developed in this invention addresses both the requirements for wide signal coverage and the need to avoid damaging the aircraft's mechanical structure when not in use. When the antenna is needed for different applications, it extends out of the aircraft surface; when operation is complete, it retracts into the fuselage, conforming to the aircraft's outer surface. This convenient design offers superior deployment and retrieval performance, better meeting the practical application requirements of small aircraft.

[0043] The present invention has the following beneficial effects: 1. The retractable reconfigurable antenna servo control system developed in this study is based on a modular and miniaturized design, which reduces the number of antennas required, lowers costs, and greatly avoids electromagnetic interference between antennas, solving the problem of limited installation space on aircraft; 2. Compared with existing antenna designs, which either use multiple conformal antennas fixedly installed on the aircraft surface, making the antennas themselves non-retractable, or use retractable antennas built on the outside of the aircraft, which cause inconvenience in placement and carrying, this design combines the advantages of both. Moreover, this invention has high integration, strong compatibility, and can be widely used in antennas in different situations.

[0044] Through the description of specific embodiments, a more in-depth and specific understanding should be gained of the technical means and effects adopted by the present invention to achieve the intended purpose. However, the accompanying drawings are only provided for reference and illustration and are not intended to limit the present invention.

Claims

1. A retractable reconfigurable antenna servo control system, characterized by, The retractable reconfigurable antenna is mounted on an aircraft, and the servo control system is used to control the retracting and extending movement of the retractable reconfigurable antenna. When the retractable reconfigurable antenna is working, the retractable reconfigurable antenna is extended out of the surface of the aircraft. When the work is finished, the retractable reconfigurable antenna is retracted into the body and conforms to the outer surface of the aircraft. The servo control system comprises: a servo control module for receiving control instructions and outputting control signals; a servo drive module connected with the servo control module for driving the motor to move according to the control signals; a motor connected with a lead screw for driving the lead screw to move; a lead screw connected with the retractable reconfigurable antenna for driving the retractable reconfigurable antenna to complete the retracting and extending movement; a limit switch for limiting the retracting and extending position of the retractable reconfigurable antenna and feeding back a feedback signal to the servo control module; a power module for providing multiple power outputs for the servo control system; wherein the servo control module adopts a double closed loop control strategy including current closed loop and speed closed loop to realize accurate control of the motor current and speed, and judges whether the retractable reconfigurable antenna moves to the preset position based on the feedback signal of the limit switch.

2. The retractable reconfigurable antenna servo control system of claim 1, wherein, The power module comprises: a reverse connection protection circuit for reverse connection protection; an overvoltage and overcurrent protection circuit for overvoltage and overcurrent protection; a differential mode and common mode filter circuit for suppressing noise signals conducted along the power line; a surge suppression circuit for controlling the input impact current peak value within the preset current; the input voltage range of the power module is 18V to 32V DC, and the output includes +5V, +3.3V, +1.9V, +12V multiple power sources.

3. The retractable reconfigurable antenna servo control system of claim 1, wherein, The servo control module comprises a digital signal processor for executing a PID control algorithm and communicating with an external system through an RS485 interface.

4. The retractable reconfigurable antenna servo control system of claim 3, wherein, The servo control module is also used to realize antenna state reporting, electronic tag management, health state monitoring and online upgrading functions.

5. The retractable reconfigurable antenna servo control system of claim 4, wherein, The servo control module receives online upgrading instructions through a serial port to complete remote update of the control software.

6. The retractable reconfigurable antenna servo control system of claim 1, wherein, The servo drive module comprises: a motor drive chip for generating motor drive signals and brake control signals according to the control signals received from the servo control module; an optical MOS relay for amplifying and outputting the brake control signals to control the motor brake switch; a Hall current sensor for detecting the motor current and feeding back to the servo control module.

7. The retractable reconfigurable antenna servo control system of claim 1, wherein, The motor adopts a brushless DC motor, and a Hall position sensor is arranged in the motor for providing a speed feedback signal to the servo control module.

8. The retractable reconfigurable antenna servo control system of claim 1, wherein, The servo control system further comprises a non-volatile memory for storing antenna operation logs, fault data and upgrading programs.

9. A method of controlling a servo control system for a reconfigurable antenna according to any one of claims 1 to 8, characterized in that, comprises: S10, receiving retracting and extending control instructions; S20, driving the motor to drive the lead screw to move through a double closed loop control strategy; S30, detecting the limit switch signal to judge whether the retractable reconfigurable antenna is in place; if so, controlling the motor brake to engage the brake and lock the position of the retractable reconfigurable antenna; S40, reporting the antenna state and servo control system health information in real time.

10. The control method according to claim 9, characterized by, The method further comprises: when the motor is at a locked-rotor state, limiting the motor current in a safe range through current closed-loop control, and maintaining the motor output torque.

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