Unmanned aerial vehicle servo motor control circuit

Abstract

The utility model belongs to the technical field of unmanned aerial vehicle servo motor, specifically relates to unmanned aerial vehicle servo motor control circuit, including digital power supply circuit is the power supply of DSP controller and CPLD logic circuit, DSP controller is used for completing system control, correction operation, communication and fault detection, clock circuit is connected with DSP controller and provides working clock source for it, CPLD logic circuit is connected with DSP controller, is used for realizing logic control, level conversion and reads angle data from angle code disc, photo -coupler isolation circuit is connected between CPLD logic circuit and power amplifier circuit, is used for realizing the electrical isolation of digital circuit and power circuit, power amplifier circuit is connected with photo -coupler isolation circuit, is used for driving azimuth and pitch motor, relay circuit is connected with motor winding, is used for short circuit motor winding when system power failure. The utility model can solve the problem of weak anti -interference ability, not high reliability and motor free rotation under the condition of power failure in prior art.

Description

Technical Field

[0001] This utility model belongs to the field of UAV servo motor technology, specifically relating to UAV servo motor control circuits. Background Technology

[0002] The servo system of an unmanned aerial vehicle (UAV) is responsible for controlling the azimuth and pitch movements of the gimbal or antenna. Its performance directly affects the stability and accuracy of tasks such as target tracking and image transmission. The servo control module is the core of the servo system, typically including a processor, logic control, and power drive components. Existing servo control modules often use general-purpose processors or imported DSP chips, which suffer from high costs, supply chain constraints, and insufficient anti-interference capabilities in complex electromagnetic environments. Furthermore, interference can easily occur between the digital circuits and power circuits within the module, affecting system stability. In addition, in the event of an unexpected power outage, the motors may lose control and rotate freely, causing mechanical parts to collide with and damage the limit devices. Utility Model Content

[0003] The purpose of this invention is to provide a servo motor control circuit for unmanned aerial vehicles (UAVs) that can solve the problems of weak anti-interference ability, low reliability, and free rotation of the motor in the event of power failure in the existing technology.

[0004] The specific technical solution adopted by this utility model is as follows:

[0005] The UAV servo motor control circuit includes a digital power supply circuit, an analog power supply circuit, a DSP circuit, a clock circuit, a CPLD logic circuit, an optocoupler isolation circuit, a power amplifier circuit, and a relay circuit; among which the azimuth motor, pitch motor, and angle encoder are located on the turntable;

[0006] The digital power supply circuit converts the externally input 5V power supply into 3.3V and 1.9V digital power supplies to power the DSP controller and the CPLD logic circuit.

[0007] The DSP controller uses the JDSPF28335 chip as the core processor to perform system control, correction calculations, communication, and fault detection.

[0008] The clock circuit uses a crystal oscillator, which is connected to the DSP controller to provide it with a working clock source.

[0009] The CPLD logic circuit uses an HWD14288XL-10MCQFP144 chip, which is connected to the DSP controller to realize logic control, level conversion, and reading angle data from the angle encoder disk.

[0010] The optocoupler isolation circuit uses a GH0631 optocoupler, which is connected between the CPLD logic circuit and the power amplifier circuit to achieve electrical isolation between the digital circuit and the power circuit.

[0011] The power amplifier circuit uses a WBC02-10DM brushless DC motor driver, which is connected to the optocoupler isolation circuit to drive the azimuth and pitch motors.

[0012] The relay circuit uses a JZC-064M-012-01-II relay, which is connected to the motor windings and is used to short-circuit the motor windings when the system loses power.

[0013] Preferably, the CPLD logic circuit is further connected to an encoder interface circuit, which includes an azimuth encoder and a pitch encoder. The encoder interface circuit uses an RS422 level interface chip SM490 to convert differential signals to single-ended signals between the CPLD logic circuit and the angle encoder. Specifically, the encoder's input and output use an RS422 level SSI interface. The differential signal converted from the SSI interface clock signal generated by the CPLD is directly sent to the encoder via the RS422 level interface chip SM490, and the differential angle data signal sent from the encoder is converted into a single-ended signal and then connected to the CPLD. The CPLD's control logic completes the reading of the angle data. The DSP reads the angle data from the CPLD into the DSP via the data bus.

[0014] Preferably, the power amplifier circuit includes an azimuth power amplifier and a pitch power amplifier, the motor winding includes an azimuth brushless DC motor winding and a pitch brushless DC motor winding, the azimuth power amplifier is connected to the azimuth brushless DC motor, and the pitch power amplifier is connected to the pitch brushless DC motor.

[0015] Preferably, the relay circuit functions to short-circuit the motor windings after the system loses power, so that the azimuth motor and pitch motor are in generator mode. The large reduction ratio ensures that the load can only rotate slowly after the power is cut off, thus preventing the load from rotating rapidly and freely after the system loses power and violently colliding with the mechanism's limit device, which would cause damage.

[0016] Preferably, the azimuth and pitch power amplifiers are selected from Weijian Company's WBC02-10DM DC brushless motor driver, which uses pulse width modulation power amplifier, with a maximum power supply voltage of 80V, a continuous operating current of 10A, and an operating temperature range of -55 to +125°.

[0017] Preferably, the components of the servo control circuit are arranged such that the azimuth amplifier and the pitch amplifier are mounted close to the control circuit base plate to facilitate heat dissipation using the base plate.

[0018] Preferably, the CPLD logic circuit performs the internal 3.3V to 5V level conversion function of the control circuit.

[0019] The technical effects achieved by this utility model are as follows:

[0020] This invention has the advantages of high reliability: core components such as DSP, CPLD, power supply, crystal oscillator, and interface chip are all military-grade; the operating temperature is -55℃~125℃, which meets the GJB standard and ensures that the circuit works stably in harsh environments.

[0021] This invention has the advantage of strong anti-interference: the digital part and the power part are completely isolated by the optocoupler isolation circuit, and the RS422 differential interface is used to communicate with the code disk, which significantly improves the electromagnetic compatibility (EMC) performance of the system.

[0022] This utility model has the advantage of high safety protection: it is designed with a power failure braking relay circuit, which effectively prevents hardware damage caused by the load rotating freely due to inertia after the system is powered off, thus improving system safety.

[0023] This invention has the advantages of domestic production and integration: the main chip adopts a domestic solution, which reduces supply chain risks; and the integration of multiple logic functions through CPLD simplifies the circuit structure and improves the integration level.

[0024] This invention has a good heat dissipation effect: through a reasonable layout, the power amplifier circuit, which is the main heat source, is in close contact with the base plate, thus solving the heat dissipation problem under high-density installation. Attached Figure Description

[0025] Figure 1 This is a block diagram illustrating the principle of the servo control circuit of this utility model.

[0026] Figure 2 This is the DSP clock generation circuit in this utility model;

[0027] Figure 3 This is the 3.3V power supply circuit in this utility model;

[0028] Figure 4 This is the 1.9V power supply circuit in this utility model;

[0029] Figure 5 This utility model contains an optocoupler isolation circuit. Detailed Implementation

[0030] To make the objectives and advantages of this utility model clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the following text is merely used to describe one or more specific embodiments of this utility model and does not strictly limit the scope of protection specifically claimed by this utility model.

[0031] like Figure 1 As shown, the UAV servo motor control circuit includes a digital power supply circuit, an analog power supply circuit, a DSP circuit, a clock circuit, a CPLD logic circuit, an optocoupler isolation circuit, a power amplifier circuit, and a relay circuit; among which the azimuth motor, pitch motor, and angle encoder are located on the turntable.

[0032] The digital power supply circuit converts the externally input 5V power supply into 3.3V and 1.9V digital power supplies to power the DSP controller and the CPLD logic circuit. Specifically, the servo control module requires 5V, 3.3V, and 1.9V digital power supplies internally. The 5V is provided by an external power supply module, while the 3.3V and 1.9V are generated internally by the module itself. The power supply chip SM74401RWGT from Guowei Technology Co., Ltd. is selected. This chip has the following characteristics: maximum input voltage: 5.5V; maximum operating current: 3A; operating temperature: -55℃~+125℃; quality grade: Class B as specified in GJB597A-1996. The power supply circuit designed based on the selected power supply chip is as follows: Figure 3 , Figure 4 As shown; the SM74401RGWT is a single-output adjustable power supply chip. Assuming the resistor between the output terminal and pin FB is RO_FB, and the resistor between FB and ground is RG_FB, then the output voltage is: The output power supply voltage is checked and calculated based on the resistor designed in the diagram as follows: The error of both power supplies is within 0.01V, which meets the system requirements.

[0033] The DSP controller, employing the JDSPF28335 chip as its core processor, is used to perform system control, calibration calculations, communication, and fault detection. Specifically, the DSP controller is the core component of the entire system, undertaking multiple functions such as information processing, control, system detection, communication, and fault detection and handling. It is also a key component for achieving the system's performance targets. The DSP controller must possess high reliability, real-time performance, and comprehensive functionality, thus requiring careful design. After comprehensive consideration, the domestically produced control-specific floating-point DSP chip JDSPF28335 from the 58th Research Institute of China Electronics Technology Group Corporation was selected to form the system's controller. The DSP performs system control, calibration calculations, communication, and fault detection functions. The JDSPF28335 has the following features: operating temperature range: -55℃~+125℃; I / O port power supply voltage: 3.3V; core operating voltage: 1.9V; maximum clock frequency: 150MHz; addressable on-chip memory size: Flash 256k×16bit, SRAM 34k×16bit, OTP 1k×16bit, ROM 8k×16bit; external interface XINTF address bits: 20bit; on-chip low-speed peripheral I / O bus width: 16bit; external interface XINTF data bus width: 32bit; CAN bus channels: 2; PWM interface: 12 channels; other rich peripheral modules; compliance standard: GJB597A-1996, quality grade: B.

[0034] The clock circuit uses a crystal oscillator connected to the DSP controller to provide its operating clock source; specifically, the clock circuit provides the operating clock source for the DSP system and is the core of the DSP system. The crystal can be integrated with the DSP to form a crystal oscillator circuit, or the crystal oscillator can directly provide the clock source for the DSP. This design selects a crystal oscillator as the clock source for the DSP, and its circuit is as follows: Figure 2 As shown. The crystal oscillator selected is the military-grade SCXO11B-E30MBB from Chengdu Tian'ao Company. The product's operating temperature is -40℃ to +85℃, which meets the mission requirements.

[0035] The CPLD logic circuit uses an HWD14288XL-10MCQFP144 chip, connected to the DSP controller, for logic control, level conversion, and reading angle data from the angle encoder. Specifically, the CPLD logic circuit is also connected to an encoder interface circuit, which includes an azimuth encoder and a pitch encoder. The encoder interface circuit uses an RS422 level interface chip SM490, used for differential signal to single-ended signal conversion between the CPLD logic circuit and the angle encoder. Specifically, the encoder's input and output use an RS422 level SSI interface. The differential signal converted from the SSI interface clock signal generated by the CPLD is directly sent to the encoder via the RS422 level interface chip SM490, and the differential angle data signal sent from the encoder is converted into a single-ended signal before being connected to the CPLD. The CPLD's control logic reads the angle data. The DSP reads the angle data from the CPLD into the DSP via the data bus. The CPLD logic circuit performs the internal 3.3V to 5V level conversion function of the control circuit.

[0036] The optocoupler isolation circuit uses a GH0631 optocoupler, connected between the CPLD logic circuit and the power amplifier circuit, to achieve electrical isolation between the digital circuit and the power circuit. Specifically, the optocoupler isolation circuit is used to isolate the internal power circuit and digital circuit, preventing interference from the power circuit to the digital circuit. After comprehensive consideration, the high-speed optocoupler GH0631 from Beiguang was selected. This chip has the following characteristics: maximum input voltage: 5V; maximum operating speed: 10MHz; operating temperature: -55℃~+125℃; quality grade: Class B as specified in GJB597A-1996. The optocoupler isolation circuit designed based on the selected optocoupler is as follows: Figure 5 As shown;

[0037] The power amplifier circuit uses a WBC02-10DM brushless DC motor driver, connected to the optocoupler isolation circuit, to drive the azimuth and pitch motors. The power amplifier circuit includes an azimuth power amplifier and a pitch power amplifier. The motor windings include azimuth brushless DC motor windings and pitch brushless DC motor windings. The azimuth power amplifier is connected to the azimuth brushless DC motor, and the pitch power amplifier is connected to the pitch brushless DC motor. The azimuth and pitch power amplifiers use the WBC02-10DM brushless DC motor driver from Weijian Company, employing pulse width modulation power amplifiers, with a maximum power supply voltage of 80V, a continuous operating current of 10A, and an operating temperature range of -55°C to +125°C.

[0038] The relay circuit uses a JZC-064M-012-01-II relay, which is connected to the motor windings and is used to short-circuit the motor windings when the system loses power. The function of the relay circuit is to short-circuit the motor windings after the system loses power, so that the azimuth motor and pitch motor are in generator mode. The large reduction ratio ensures that the load can only rotate slowly after the power is cut off, avoiding the load from rotating rapidly and freely after the system loses power and violently colliding with the mechanism's limit device, which would cause damage.

[0039] Preferably, the components of the servo control circuit are arranged such that the azimuth amplifier and the pitch amplifier are mounted close to the control circuit base plate to facilitate heat dissipation using the base plate.

[0040] The above description is merely a preferred embodiment of this utility model. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of this utility model, and these improvements and modifications should also be considered within the scope of protection of this utility model. Structures, devices, and operating methods not specifically described or explained in this utility model, unless otherwise specified or limited, shall be implemented using conventional methods in the field.

Claims

1. A servo motor control circuit for an unmanned aerial vehicle (UAV), characterized in that: It includes digital power supply circuits, analog power supply circuits, DSP controllers, clock circuits, CPLD logic circuits, optocoupler isolation circuits, power amplifier circuits, and relay circuits; among which the azimuth motor, pitch motor, and angle encoder are located on the turntable; The digital power supply circuit converts the externally input 5V power supply into 3.3V and 1.9V digital power supplies to power the DSP controller and the CPLD logic circuit. The DSP controller, as the core processor, is used to perform system control, correction calculations, communication, and fault detection. The clock circuit uses a crystal oscillator, which is connected to the DSP controller to provide it with a working clock source. The CPLD logic circuit is connected to the DSP controller and is used to implement logic control, level conversion, and reading angle data from the angle encoder. The optocoupler isolation circuit is connected between the CPLD logic circuit and the power amplifier circuit to achieve electrical isolation between the digital circuit and the power circuit. The power amplifier circuit uses a DC brushless motor driver, which is connected to the optocoupler isolation circuit to drive the azimuth and pitch motors. The relay circuit is connected to the motor windings and is used to short-circuit the motor windings when the system loses power.

2. The UAV servo motor control circuit according to claim 1, characterized in that: The CPLD logic circuit is also connected to a code disk interface circuit, which includes an azimuth code disk and a pitch code disk. The code disk interface circuit is used to convert differential signals to single-ended signals between the CPLD logic circuit and the angle code disk.

3. The UAV servo motor control circuit according to claim 2, characterized in that: The power amplifier circuit includes an azimuth power amplifier and a pitch power amplifier. The motor windings include an azimuth brushless DC motor winding and a pitch brushless DC motor winding. The azimuth power amplifier is connected to the azimuth brushless DC motor, and the pitch power amplifier is connected to the pitch brushless DC motor.

4. The UAV servo motor control circuit according to claim 3, characterized in that: The function of the relay circuit is to short-circuit the motor windings after the system loses power, so that the azimuth motor and pitch motor are in generator mode, and the large reduction ratio is used to ensure that the load can only rotate slowly after the power is cut off.

5. The UAV servo motor control circuit according to claim 4, characterized in that: The azimuth and elevation power amplifiers are pulse width modulation power amplifiers with a maximum power supply voltage of 80V, a continuous operating current of 10A, and an operating temperature range of -55 to +125°.

6. The UAV servo motor control circuit according to claim 5, characterized in that: The component layout of the servo motor control circuit is as follows: the azimuth amplifier and the pitch amplifier are mounted close to the control circuit base plate.

7. The UAV servo motor control circuit according to claim 6, characterized in that: The CPLD logic circuit completes the internal 3.3V and 5V level conversion function of the control circuit.

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