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The Electronic Circuit Design Of UAVs

2017-06-15 16:52:43 | 日記

Man-made is compared to satellite and manned aircraft aircraft remote sensing platform, with low cost, high flexibility characteristics. In order to meet the scientific remote sensing experiment, complete the task of remote sensing, coordinate the work of multi-component in the electronic pod of the UAV, and control the attitude of the remote sensing image sensor. The system uses the AT89S52 as the master chip to expand the serial port and USB interface to realize the system and peripheral equipment of the communication, while the design of the camera driver module and three degrees of freedom stepper motor drive module. The remote sensing experiment proves that the system can meet the requirements of remote sensing experiment.

USB port expansion by the CH375 chip. CH375 is a USB bus common interface chip. Its main feature is the cheap, easy interface, high reliability. Supports USB-HOST host mode and USB-DEVICE / SLAVE device mode. CH375 USB host mode supports the commonly used USB full speed device, the external microcontroller needs to write a firmware program in accordance with the corresponding USB protocol and USB device communication. But for commonly used USB storage devices, CH375's built-in firmware can automatically handle Mass-Storage mass storage devices dedicated communication protocol, usually, the external microcontroller does not need to write firmware. You can directly read and write data in the USB storage device. CH375 and single-chip communication in two ways: parallel and serial mode. USB expansion circuit schematic diagram shown in Figure 3, CH375 chip is set to built-in firmware mode, the use of 12 MHz crystal. MCU P0 port and CH375 D0 ~ D7 connected as a data bus, the decoder output CH375 connected chip select the chip, microcontroller A0 and CH375 A0 connected to the choice of CH375 address or data input and output. When A0 is high is the D0 ~ D7 transmission is the address, low when the data is transmitted. P3.6 and P3.7 control the read and write operations of CH375 respectively. CH375 then single-chip input, when there is data through the USB port input interrupt signal, notify the microcontroller for data processing. When the CH375 chip is initialized and successfully connected to the host, the indicator light electronic components.

Stable PTZ control is the control of the three-degree-of-freedom stepper motor, which controls the pitch, roll angle and heading angle of the remote sensing sensor to keep the pan / tilt head horizontally (or vertically). Stepper motor driven by the THB6128 chip to achieve, single-chip only need to output stepper motor running direction and pulse signal can be achieved to control the purpose of stepper motor.You maybe familiar withatmega328p datasheet and nrf51822 datasheet.

THB6128 is a high-resolution two-phase hybrid stepper motor driver dedicated chip, through the single-chip output control signal, you can design a high-performance, multi-segmented drive circuit. Features a dual full-bridge MOSFET driver with low on-resistance Ron = 0.55 Ω, maximum withstand voltage of 36 V, high current 2.2 A (peak), multiple subdivisions, up to 128 segments, with Automatic half-flow lock function, fast failure, slow decay, mixed attenuation 3 kinds of attenuation options, built-in temperature protection and overcurrent protection. Figure 4 for the heading angle stepper motor drive circuit, pitch angle, roll angle stepper motor drive the same. In the figure, CP1 and U / D are the driving pulse and the motor running direction control signal given by the single chip. M1, M2, M3 for the motor to drive fine-fractional selection signal input, by the DIP switch man-made control. FDT1 and VREG1 are the attenuation mode selection voltage and current control voltage input. Is a slow decay mode when 3.5 V; when mixed attenuation mode; when FDT1 "0.8 V is fast decay mode. Adjust the VREG1 terminal voltage to set the stepper motor drive current value.

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