微型四轴飞行器原理图及PCB布线
四轴飞行器：让PCB板飞！
四轴飞行器：让PCB板飞！我们在制作一个非常袖珍的四轴飞行器，就用PCB作为承力结构。
第一个版本被命名为疯狂直升机。
它的主要特点有：•STM32 Cortex-M3 CPU•3轴加速度计•1轴/2轴陀螺仪•Nordic 2.4GHz 射频通信芯片•电动机，螺旋桨和银辉（Silverlit）X翼模型飞机的电池这架直升机可以从电脑上通过USB无线适配器遥控。
我们制作了三架样品（每个成员各一架），并完成了大多数的固件程序。
为了达到稳定飞行的目的，还需要解决一些控制上的问题，以及完成电脑上的控制程序模块。
更多的信息和实际飞行视频会在稍后公布:)第一个飞行视频这是直升机的第一段飞行影像。
控制系统工作的很棒，但是它仍然过于依赖操纵者的敏捷（见视频的结尾部分）。
这架直升机是通过PC机上运行的Python程序控制的，我们实际上用一个游戏机的蓝牙手柄来操纵它。
疯狂直升机四轴飞行器详述像承诺过的那样，我们要在这里公布疯狂直升机（也是我们第一架四轴飞行器）的更多信息。
该系统的主要架构如下：疯狂直升机的高层次系统图。
直升机本身是围绕CPU组织起来的。
CPU的任务是读取物理传感器（陀螺仪和加速度计）的测量结果，给出控制信号控制电机，让直升机保持稳定。
通过一个控制反馈回路，CPU每秒能够对电机发送250次调节转速的指令。
无线通信的带宽需求很低，仅仅需要发送操作命令和接受遥测数据。
CPU上运行的程序可以通过无线通信更新。
控制和遥测程序在电脑上运行，控制程序从手柄读取输入，然后向直升机发送命令。
我们也有调节直升机上控制参数的程序模块，并且会记录下传感器的测量结果，方便调整控制回路。
所有这些开发工作在Windows或linux系统上完成。
事实上有三个人同时在这个项目上工作，两个人在Linux上工作，剩下一个人主要使用Windows。
利用自由/开源软件（FLOSS，Free/Libre and Open Source Software）许可对提高工作效率非常有帮助。
R5F100LE控制的四旋翼自主飞行器,含原理图、程序
式 1-1
y
z ]T 为四旋翼飞行器在导航坐标系下的线位移， [ x y z ]T 为运动加速度，m
为飞行器质量， , , 分别为机体的偏航角、俯仰角和横滚角，l 为旋翼面中心到四旋翼飞行 器质心的距离，I X , IY , I Z 为轴向惯性主矩。该动力学模型对四旋翼飞行器的真实飞行状态进 行了合理的简化，忽略了空气阻力等对系统运行影响较小的参数，使得飞行控制算法更加简 洁。 2.2 PID 控制算法结构分析 在动力学模型的基础上，将小型四旋翼飞行器实时控制算法分为两个控制回路，即位置
其中， xd , yd , zd 为航姿参考系统测量到的加速度积分得到的位移量。
1.2 电机的选择与论证
四旋翼无人飞行器是通过控制四个不同无刷直流电机的转速，达到控制四旋翼无人飞行 器的飞行姿态和位置，与传统直升机通过控制舵机来改变螺旋桨的桨距角，达到控制直升机 的目的不同。在电机的选型上，主要有直流有刷电机和直流无刷电机两种。 方案一：直流有刷电机是当前普遍使用的一种直流电机，它的驱动电路简单、控制方法 成熟，但是直流有刷电机使用电刷进行换向，换向时电刷与线圈触电存在机械接触，电机长 时间高速转动使极易因磨损导致电气接触不良等问题，而且有刷电机效率低、力矩小、重量 大，不适合对功率重量比敏感的电动小型飞行器。 方案二：直流无刷电机能量密度高、力矩大、重量轻，采用非接触式的电子换向方法， 消除了电刷磨损，较好地解决了直流有刷电机的缺点，适用于对功率重量比敏感的用途，同 时增强了电机的可靠性。
-2-
所以选择直流无刷电机作为动力源。
1.3 电机驱动方案的选择与论证
方案一:采用电阻网络或数字电位器调整电动机的分压，从而达到调速的目的。但是电阻 网络只能实现有级调速，而数字电阻的元器件价格比较昂贵。更主要的问题在于一般电动机 的电阻很小，但电流很大；分压不仅会降低效率，而且实现很困难。 方案二:采用继电器对电动机的开或关进行控制，通过开关的切换对小车的速度进行调 整。这个方案的优点是电路较为简单，缺点是继电器的响应时间慢、机械结构易损坏、寿命 较 短、可靠性不高。 方案三:采用全桥驱动 PWM 电路。这种驱动的优点是使管子工作在占空比可调的开关状 态，提高使用效率实现电机转速的微调。并且保证了可以简单的方式实现方向控制。 基于上述理论分析，选择方案三。
自制四轴飞行器之路
自制四轴飞行器之路
四轴飞行器，又称四旋翼飞行器，简称四轴、四旋翼。
四轴飞行器的四个螺旋桨与电机直接相连，通过改变电机转速获得旋转机身的力，从而调整自身姿态。
四轴的叶片转速极高，有一定的危险性，一般不能在室内飞，特别是在调试过程中更加不稳定，轻则炸鸡撞坏物品，重则伤到人。
我做四轴的主要目的是为了学习飞控算法，这个过程肯定少不了调试，为了安全，我选择做一个小一点的，手掌那么大的四轴，叶片的威力比较小，价格也便宜，即使摔坏也不心疼。
这种小四轴一般采用PCB做机架，用720空心杯电机代替无刷电机，用MOS管代替电调，电池采用3.7v锂聚合物电池（尺寸跟手机电池差不多，但是放电电流要大很多），遥控用2.4G无线模块，或者用蓝牙连接手机，成本100左右，续航时间大概6-7分钟，遥控距离在10米以内。
选择零件
四轴上最重要的就是飞控，所以第一步：选择飞控。
市面上有许多现成飞控，也可以自己用电子元件做一个分控。
有很多有名的开源飞控，例如KK，QQ，匿名，MultiWii/MWC，APM/PIX等。
KK、QQ飞控功能较少，只有基本的四轴飞行功能，甚至不支持GPS。
匿名飞控是国内新出现的飞控，功能比以上两个要多，价格也要贵很多。
MultiWii/MWC飞控是基于arduino的，支持GPS，能路线规划，在线调试。
APM也是基于arduino的，功能更为齐全，硬件也更为复杂，飞控中有两块单片机，分别执行不同功能。
APM已将arduino的性能开发到极限，于是有了升级版PIX，从arduino 转到了STM32，处理速度提升了10倍，同样用了两块不同型号的STM32协同运作，是目前已知的最好的开源飞控。
微型四旋翼飞行器的系统设计
10 | 电子制作 2019年02-03月用“正反桨”，1号和4号电机作为“正桨”，顺时针旋转提供向上的升力，2号和3号电机作为“反桨”，逆时针旋转提供向上升力。
本文设计了一款结构简单、性能卓越，基于遥控器控制和手机APP 两种控制模式的四旋翼飞行器。
图1 四旋翼飞行器飞行模式图1 硬件模块四旋翼飞行器包括姿态检测单元、处理器、电机驱动等模块。
以低功耗MSP430F5529微处理器为系统控制器，陀螺仪ITG3205、加速度计ADXL345等作姿态检测，以2.4GHz 频段的无线通信方式进行遥控，总体设计框图如图2所示。
动，而内部线圈固定，在扭力，和转速等上具有优越的性能，每个电机都需要电调驱动。
调制信号为50Hz 的PWM 波，其占空比范围是0~100%。
微型飞行器体积小，重量轻。
采用有刷电机（空心杯电机），MOS 管驱动，具有以下优良特性：（1）能效高：能量转换效率很高，一般在70%以上。
（2）启动快：启动极快，一般小于28ms，好的产品甚至可以达到10ms 以内。
（3）其他：运行稳定，转速波动小，重量轻等。
MOS 管驱动的原理是：当输入端是高电平时，MOS 管导通、电机转动；当输入是低电平时MOS 管截止、电机停止旋转，所以PWM 信号的占空比可以调节电机的转速。
■1.2 控制器模块飞行控制以MSP430F5529为控制器，通过对姿态检测单元（陀螺仪、加速度计、磁力计）数据分析，确定飞行姿态。
调节PWM 波的占空比实现对电机的转速的控制，进而控制飞行器。
MSP430F5529单片机在性能和功耗方面取得了较大的突破，低功耗是其最大的特点，主频频率最高可达25MHz。
飞行器通常有两种模式如图1所示，“十”模式和“×”模式。
因较于“十”模式，“×”模式控制更加灵活，因此采用“×”模式。
姿态检测模块包括三轴陀螺仪ITG3205、加速度计ADXL345、磁力计MAG3110。
全球最小四轴飞行器Crazyflie电路部分详解
全球最小四轴飞行器Crazyflie电路部分详解上网日期: 2016年02月16日Crazyflie是目前全世界最小的四轴飞行器，仅重19克，相对的两翼之间长度为9厘米。
有两个不同的版本，区别在于传感器的数量。
这个小四轴飞行器可以在空中飞行长达7分钟,通过一个标准的USB接头给锂聚合物电池充电需要约20分钟。
它的电路部分到底是如何实现的？且听我慢慢道来。
1. 电气原理从中心开始：72M主频的M3内核的处理器来处理各传感器数据，并对四个旋翼进行控制达到想要的效果。
往上：通过IIC接口与三轴陀螺仪、三轴加速度计（也就是MPU6050）、磁力计、气压计等传感器连接获取传感器数据，来感知载体（也就是四轴机体）的姿态（这里的姿态包括俯仰、横滚、航向）和高程。
往下：通过PWM调节四个电机驱动器来驱动四个电机转动，由于电机带有螺旋桨转动而产生所谓的“升力”。
往右：通过SPI协议接口与无线芯片通讯，回传载体数据和接收控制信号，还有外部扩展接口。
往左：电源管理部分。
2. 电池电池使用的是锂电池（锂离子聚合物电池），是目前流行的遥控模型电池。
但锂电池必须按照规定使用，过冲、过放都会产生安全隐患。
由于它具有最高的电能/质量比和最大的放电电流，所以也是比较适合的选择。
为了应付锂电池的这些缺点，我们使用电路保护模块（PCM）来防止电量不足、过放电或者短路。
PCM 位于电池上部的橙色胶带下面，从中引出两条电源线。
但是这种保护是远远不够的，还需要有专门的充放电管理电路来保护。
比如电气原理图的Power Mangment and Charging部分。
PCM 的参数如下：3. 电源管理电源管理主要是由TI BQ24075 电源管理芯片来完成。
它能开/关和给锂电池充电。
BQ24075有三种输入限制模式，100mA，500mA和用户自定义（Crazyflie设置740mA）。
当将Crazyflie 接上普通电源适配器时就可以使它能快速的充电。
四轴飞行器飞行原理与双闭环PID控制
四轴飞行器是微型飞行器的其中一种，相对于固定翼飞行器，它的方向控制灵活、抗干扰能力强、飞行稳定，能够携带一定的负载和有悬停功能，因此能够很好地进行空中拍摄、监视、侦查等功能，在军事和民用上具备广泛的运用前景。
四轴飞行器关键技术在于控制策略。
由于智能控制算法在运行复杂的浮点型运算以及矩阵运算时，微处理器计算能力受限，难以达到飞行控制实时性的要求；而PID控制简单，易于实现，且技术成熟，因此目前主流的控制策略主要是围绕传统的PID控制展开。
1 四轴飞行器的结构与基本飞行原理四轴飞行器结构主要由主控板和呈十字交叉结构的4个电子调速器、电机、旋浆组成，电机由电子调速器控制，主控板主要负责解算当前飞行姿态、控制电调等功能。
以十字飞行模式为例，l号旋翼为头，1、3号旋翼逆时针旋转，2、4号旋翼顺时针旋转，如图1所示。
图1 四轴飞行器结构图参照飞行状态表1变化电机转速，由于四个电机转速不同，使其与水平面倾斜一定角度，如图l所示。
四个电机产生的合力分解为向上的升力与前向分力。
当重力与升力相等时，前向分力驱动四轴飞行器向倾斜角度的方向水平飞行。
空间三轴角度欧拉角分为仰俯角、横滚角、航向角：倾斜角是仰俯角时，向前、向后飞行；倾斜角是横滚角时，向左、向右飞行；而倾斜航向角时，向左、右旋转运动，左(右)旋转是由于顺时针两电机产生的反扭矩之和与逆时针两电机产生的反扭矩之和不等，即不能相互抵消，机身便在反扭矩作用下绕z轴自旋转。
2 姿态解算四轴飞行器运用姿态解算计算出空间三轴欧拉角。
结构框架如图2所示，陀螺仪采样三轴角速度值，加速度传感器采样三轴加速度值，而磁力传感器采样得到三轴地磁场值，将陀螺仪、加速度传感器、磁力传感器采样后的数据进行标定、滤波、校正后得到三轴欧拉角度，其中陀螺仪和加速度传感器选用MPU6050芯片，磁力传感器选用HMC5883L芯片，采用IIC总线与主控板通信。
图2 姿态解算结构图由于传感器存在器件误差，因此在使用前需要标定。
小型四轴飞行器控制器设计的研究
小型四轴飞行器控制器设计的研究【摘要】四轴飞行器是一种有4个螺旋桨呈十字形交叉的飞行器，能任意角度灵活移动，操控简单，飞行稳定。
本文研究的主要是基于STM32单片机的四轴飞行器控制器的设计方法，应用集成的三轴陀螺仪和三轴加速度计感受姿态信息，来实现飞行器定向、定点、定高的飞行控制，具有较好的应用前景。
【关键词】STM32单片机;四轴飞行器;控制系统引言四轴飞行器在军事、工业和民用方面都有广泛的应用，可应用于地面战场的侦察和监视，可以用在安全巡检，可用于灾后搜救、城市交通巡逻等诸多领域[1]。
四轴飞行器还具备造价低、维护简单、可重复性强以及事故代价低等特点，因此，四轴飞行器的研究意义重大。
目前随着单片机技术和传感器技术的发展，在高校大学生的创新实践活动中对四轴飞行器的研究也越来越多，各种设计方案及应用范围各有特点，有的侧重于机械结构的研究，有的专注于控制算法的研究，本文重点介绍一种以STM32F103VCT6单片机为核心的四轴飞行器硬件系统设计的方案。
1.四轴飞行器的结构和控制原理四轴飞行器由四个成十字交叉对称安装的电机带动四个螺旋桨构成动力系统，为降低机身重量，机架通常用机械强度较高的碳素管或PVC管来做，微小型的四轴飞行器的机架也可以直接用PCB板切割而成。
四轴飞行器的机械结构如图1所示。
图1 四轴飞行器结构图图2 四轴飞行器姿态控制原理图四轴飞行器的升降、悬停、俯仰、横滚等飞行姿态的控制，完全由控制四个电机的转速变化来实现，如图2所示[2]。
为了使整个机体转矩平衡，采用正反桨设计，即对角线的一对螺旋桨相同，相邻的两个螺旋桨桨叶相反，这样正常飞行时两个螺旋桨正转两个螺旋桨反转，电机的转矩抵消，可以避免飞行器打转。
当提高螺旋桨的转速产生的升力大于飞行器自身重量时，飞行器就可以飞离地面，当对角线上的一对螺旋桨的转速不同，使机体倾斜一个角度产生水平分力推动飞行器平移，飞行速度可以由俯仰角的大小与电机的转速来控制[3]。
四轴飞行器 遥控 硬件+全套源代码 + 飞控Arm Cortex 硬件原理图PCB 联系
BK2425Low Power High Performance 2.4 GHz GFSK Transceiver Features Pin Assignments⏹2400-2483.5 MHz ISM band operation⏹Support 250Kbps, 1Mbps and 2 Mbps airdata rate⏹Programmable output power⏹Low power consumption⏹Tolerate +/- 60ppm 16 MHz crystal⏹Variable payload length from 1 to 32bytes⏹Automatic packet processing⏹ 6 data pipes for 1:6 star networks⏹ 1.9V to 3.6V power supply⏹4-pin SPI interface with maximum 8 MHzclock rate⏹20-pin 4x4mm QFN packageApplications⏹Wireless PC peripherals⏹Wireless gamepads⏹Wireless audio⏹Remote controls⏹Home automation⏹ToysBlock DiagramNC CDVDD VDD VSS VDD20 19 18 17 16CE 1 15 VDDCSN 2 14 VSSSCKBK2425 RF3 13MOSI 4 12 NCMISO 5 11 NC6 7 8 9 10IRQ NC NC XO XI四轴飞行器遥控硬件+全套源代码 + 飞控Arm Cortex 硬件原理图PCB 联系：QQ 766384919RFPFMData SlicerRx FIFOInterfaceSPICSN RFN SCKDemodulatorMOSIMISOIntegratedPowerPacketIRQ TDD RF Processing &ManagementTransceiver State Control CEFM ModulatorGaussianbanksRegistershaping Tx FIFOXTALP XTALNRevision 1.0 Copyright © 2013 Beken Corporation Jan, 2013 Page 1 of 30BK2425 Table of Contents1 General Description (3)2 Abbreviations (4)3 Pin Information (5)4 State Control (6)4.1 State Control Diagram (6)4.2 Power Down Mode (7)4.3 Standby-I Mode (7)4.4 Standby-II Mode (7)4.5 TX Mode (7)4.6 RX Mode (8)5 Packet Processing (8)5.1 Packet Format (8)5.1.1 Preamble (9)5.1.2 Address (9)5.1.3 Packet Control (9)5.1.4 Payload (10)5.1.5 CRC (10)5.2 Packet Handling (10)6 Data and Control Interface (11)6.1 TX/RX FIFO (11)6.2 Interrupt (11)6.3 SPI Interface (12)6.3.1 SPI Command (12)6.3.2 SPI Timing (13)7 Register Map (15)7.1 Register Bank 0 (15)7.2 Register Bank 1 (21)8 Electrical Specifications (22)9 Typical Application Schematic (23)10 Package and Die Bonding Information (24)10.1 Package Information (24)10.2 Die Bonding Information (25)10.3 PCB Bonding diagram (27)11 Order Information (28)12 Contact Information (29)13 Update History (30)BK2425 1 General DescriptionBK2425 is a GFSK transceiver operating in theworld wide ISM frequency band at 2400-2483.5 MHz. Burst mode transmission and upto 2Mbps air data rate make them suitable forapplications requiring ultra low powerconsumption. The embedded packet processingengines enable their full operation with a verysimple MCU as a radio system. Auto re-transmission and auto acknowledge givereliable link without any MCU interference.BK2425 operates in TDD mode, either as atransmitter or as a receiver.The RF channel frequency determines thecenter of the channel used by BK2425. Thefrequency is set by the RF_CH register inregister bank 0 according to the followingformula: F0= 2400 + RF_CH (MHz). Theresolution of the RF channel frequency is1MHz.A transmitter and a receiver must beprogrammed with the same RF channelfrequency to be able to communicate with eachother.The output power of BK2425 is set by theRF_PWR bits in the RF_SETUP register.Demodulation is done with embedded dataslicer and bit recovery logic. The air data ratecan be programmed to 250Kbps, 1Mbps or2Mbps by RF_DR_HIGH and RF_DR_LOWregister. A transmitter and a receiver must beprogrammed with the same setting.In the following chapters, all registers are inregister bank 0 except with explicit claim.RFPFMData SlicerRx FIFOInterfaceSPICSN RFN SCKDemodulatorMOSIMISOIntegratedPowerPacketIRQ TDD RF Processing &ManagementTransceiver State Control CEFM ModulatorGaussianbanksRegistershaping Tx FIFOXTALP XTALNFigure 1 BK2425 Chip Block DiagramBK2425 2 AbbreviationsACK AcknowledgementARC Auto Retransmission CountARD Auto Retransmission DelayCD Carrier DetectionCE Chip EnableCRC Cyclic Redundancy CheckCSN Chip Select NotDPL Dynamic Payload LengthFIFO First-In-First-OutGFSK Gaussian Frequency Shift KeyingGHz GigahertzLNA Low Noise AmplifierIRQ Interrupt RequestISM Industrial-Scientific-MedicalLSB Least Significant BitMAX_RT Maximum RetransmitMbps Megabit per secondMCU Microcontroller UnitMHz MegahertzMISO Master In Slave OutMOSI Master Out Slave InMSB Most Significant BitPA Power AmplifierPID Packet Identity BitsPLD PayloadPRX Primary RXPTX Primary TXPWD_DWN Power DownPWD_UP Power UpRF_CH Radio Frequency ChannelRSSI Received Signal Strength IndicatorRX ReceiveRX_DR Receive Data ReadySCK SPI ClockSPI Serial Peripheral InterfaceTDD Time Division DuplexTX TransmitTX_DS Transmit Data SentXTAL CrystalBK2425 3 Pin InformationNC CDVDD VDD VSS VDD20 19 18 17 16CE 1 15 VDDCSN 2 14 VSSBK2425 RFSCK 3 13MOSI 4 12 NCMISO 5 11 NC6 7 8 9 10IRQ NC NC XO XIFigure 2 BK2425 pin assignments (top view) for the QFN20 packagePIN Name Pin Function Description1 CE Digital Input Chip Enable Activates RX or TX mode2 CSN Digital Input SPI Chip Select, Active low3 SCK Digital Input SPI Clock4 MOSI Digital Input SPI Slave Data Input5 MISO Digital Output SPI Slave Data Output with tri-state option6 IRQ Digital Output Maskable interrupt pin, Active low7 NC No Connection8 NC No Connection9 XO Analog Output Crystal oscillator, node P (inverter output)10 XI Analog Input Crystal oscillator, node N (inverter input)11 NC No Connection12 NC No Connection13 RFN RF port RF output (PA) /Input (LNA), port N.14 VSS Ground Ground (0 V)15 VDD Power Power Supply (1.9 V to 3.6 V DC)16 VDD Power Supply (1.9 V to 3.6 V DC)17 VSS Ground Ground (0 V)18 VDD Power Power Supply (1.9 V to 3.6 V DC)19 CDVDD Analog Output Digital regulator output decoupling capacitor20 NC No ConnectionTable 1 BK2425 QFN20 pin functionsRevision 1.0Proprietary and Confidential Page 5 of 30BK24254 State Control4.1 State Control Diagram⏹ Pin signal: VDD, CE⏹ SPI register: PWR_UP, PRIM_RX, EN_AA, NO_ACK, ARC, ARD⏹System information: Time out, ACK received, ARD elapsed, ARC_CNT, TX FIFO empty, ACK packet transmitted, Packet receivedBK2425 has built-in state machines that control the state transition between different modes.When auto acknowledge feature is disabled, state transition will be fully controlled by MCU.Figure 3 PTX (PRIM_RX=0) state control diagramBK2425Figure 4 PRX (PRIM_RX=1) state control diagram4.2 Power Down ModeIn power down mode BK2425 is in sleep mode with minimal current consumption. SPI interface is still active in this mode, and all register values are available by SPI. Power down mode is entered by setting the PWR_UP bit in the CONFIG register to low.4.3 Standby-I ModeBy setting the PWR_UP bit in the CONFIG register to 1 and de-asserting CE to 0, the device enters standby-I mode. Standby-I mode is used to minimize average current consumption while maintaining short start-up time. In this mode, part of the crystal oscillator is active. This is also the mode which the BK2425 returns to from TX or RX mode when CE is set low.4.4 Standby-II ModeIn standby -II mode more clock buffers are active than in standby-I mode and much more current is used. Standby-II occurs when CE is held high on a PTX device with empty TX FIFO. If a new packet is uploaded to the TX FIFO in this mode, the device will automatically enter TX mode and the packet is transmitted.4.5 TX Mode⏹ PTX device (PRIM_RX=0)The TX mode is an active mode where the PTX device transmits a packet. To enter this mode from power down mode, the PTX device must have the PWR_UP bit set high, PRIM_RX bit set low, a payload in the TX FIFO, and a high pulse on the CE for more than 10µs.BK2425The PTX device stays in TX mode until it finishes transmitting the current packet. If CE = 0 it returns to standby-I mode. If CE = 1, the next action is determined by the status of the TX FIFO. If the TX FIFO is not empty the PTX device remains in TX mode, transmitting the next packet. If the TX FIFO is empty the PTX device goes into standby-II mode. It is important to never stay in TX mode for more than 4ms at one time.If the auto retransmit is enabled (EN_AA=1) and auto acknowledge is required (NO_ACK=0), the PTX device will enter TX mode from standby-I mode when ARD elapsed and number of retried is less than ARC.⏹ PRX device (PRIM_RX=1)The PRX device will enter TX mode from RX mode only when EN_AA=1 and NO_ACK=0 in received packet to transmit acknowledge packet with pending payload in TX FIFO.4.6 RX Mode⏹ PRX device (PRIM_RX=1)The RX mode is an active mode where the BK2425 radio is configured to be a receiver. To enter this mode from standby-I mode, the PRX device must have the PWR_UP bit set5 Packet Processinghigh, PRIM_RX bit set high and the CE pin set high. Or PRX device can enter this mode from TX mode after transmitting an acknowledge packet when EN_AA=1 and NO_ACK=0 in received packet.In this mode the receiver demodulates the signals from the RF channel, constantly presenting the demodulated data to the packet processing engine. The packet processing engine continuously searches for a valid packet. If a valid packet is found (by a matching address and a valid CRC) the payload of the packet is presented in a vacant slot in the RX FIFO. If the RX FIFO is full, the received packet is discarded.The PRX device remains in RX mode until the MCU configures it to standby-I mode or power down mode.In RX mode a carrier detection (CD) signal is available. The CD is set to high when a RF signal is detected inside the receiving frequency channel. The internal CD signal is filtered before presented to CD register. The RF signal must be present for at least 128 µs before the CD is set high.⏹ PTX device (PRIM_RX=0)The PTX device will enter RX mode from TX mode only when EN_AA=1 and NO_ACK=0 to receive acknowledge packet.5.1 Packet FormatThe packet format has a preamble, address, packet control, payload and CRC field.Preamble 1 byteAddress 3~5 byte Packet Control 9/0 bit Payload 0~32 byte CRC 2/1 bytePayload Length 6 bitPID 2 bitNO_ACK 1 bitFigure 5 Packet FormatBK24255.1.1PreambleThe preamble is a bit sequence used to detect 0 and 1 levels in the receiver. The preamble is one byte long and is either 01010101 or 10101010. If the first bit in the address is 1 the preamble is automatically set to 10101010 and if the first bit is 0 the preamble is automatically set to 01010101. This is done to ensure there are enough transitions in the preamble to stabilize the receiver.5.1.2AddressThis is the address for the receiver. An address ensures that the packet is detected by the target receiver. The address field can be configured to be 3, 4, or 5 bytes long by the AW register.The PRX device can open up to six data pipes to support up to six PTX devices with unique addresses. All six PTX device addresses are searched simultaneously. In PRX side, the data pipes are enabled with the bits in the EN_RXADDR register. By default only data pipe 0 and 1 are enabled.Each data pipe address is configured in the RX_ADDR_PX registers.Each pipe can have up to 5 bytes configurable address. Data pipe 0 has a unique 5 byte address. Data pipes 1-5 share the 4 most significant address bytes. The LSB byte must be unique for all 6 pipes.To ensure that the ACK packet from the PRX is transmitted to the correct PTX, the PRX takes the data pipe address where it received the packet and uses it as the TX address when transmitting the ACK packet.On the PRX, the RX_ADDR_Pn, defined as the pipe address, must be unique. On the PTX the TX_ADDR must be the same as the RX_ADDR_P0 on the PTX, and as the pipe address for the designated pipe on the PRX. No other data pipe can receive data until a complete packet is received by a data pipe that has detected its address. When multiple PTX devices are transmitting to a PRX, the ARD can be used to skew the auto retransmission so that they only block each other once.5.1.3Packet ControlWhen Dynamic Payload Length function is enabled, the packet control field contains a 6 bit payload length field, a 2 bit PID (Packet Identity) field and, a 1 bit NO_ACK flag.⏹Payload lengthThe payload length field is only used if the Dynamic Payload Length function is enabled.⏹PIDThe 2 bit PID field is used to detect whether the received packet is new or retransmitted. PID prevents the PRX device from presenting the same payload more than once to the MCU. The PID field is incremented at the TX side for each new packet received through the SPI. The PID and CRC fields are used by the PRX device to determine whether a packet is old or new. When several data packets are lost on the link, the PID fields may become equal to the last received PID. If a packet has the same PID as the previous packet, BK2425 compares the CRC sums from both packets. If the CRC sums are also equal, the last received packet is considered a copy of the previously received packet and discarded.⏹NO_ACKThe NO_ACK flag is only used when the auto acknowledgement feature is used. Setting the flag high, tells the receiver that the packet is not to be auto acknowledged.The PTX can set the NO_ACK flag bit in the Packet Control Field with the command: W_TX_PAYLOAD_NOACK. However, the function must first be enabled in the FEATURE register by setting theRevision 1.0Proprietary and Confidential Page 9 of 30BK2425EN_DYN_ACK bit. When you use this option, the PTX goes directly to standby-I mode after transmitting the packet and the PRX does not transmit an ACK packet when it receives the packet.5.1.4PayloadThe payload is the user defined content of the packet. It can be 0 to 32 bytes wide, and it is transmitted on-air as it is uploaded (unmodified) to the device.The BK2425 provides two alternatives for handling payload lengths, static and dynamic payload length. The static payload length of each of six data pipes can be individually set. The default alternative is static payload length. With static payload length all packets between a transmitter and a receiver have the same length. Static payload length is set by the RX_PW_Px registers. The payload length on the transmitter side is set by the number of bytes clocked into the TX_FIFO and must equal the value in the RX_PW_Px register on the receiver side. Each pipe has its own payload length.Dynamic Payload Length (DPL) is an alternative to static payload length. DPL enables the transmitter to send packets with variable payload length to the receiver. This means for a system with different payload lengths it is not necessary to scale the packet length to the longest payload.With DPL feature the BK2425 can decode the payload length of the received packet automatically instead of using the RX_PW_Px registers. The MCU can read the length of the received payload by using the command: R_RX_PL_WID.In order to enable DPL the EN_DPL bit in the FEATURE register must be set. In RX mode the DYNPD register has to be set. A PTX that transmits to a PRX with DPL enabled must have the DPL_P0 bit in DYNPD set. 5.1.5CRCThe CRC is the error detection mechanism in the packet. The number of bytes in the CRC is set by the CRCO bit in the CONFIG register. It may be either 1 or 2 bytes and is calculated over the address, Packet Control Field, and Payload.The polynomial for 1 byte CRC is X8 + X2 + X + 1. Initial value is 0xFF.The polynomial for 2 byte CRC is X16 + X12 + X5 + 1. Initial value is 0xFFFF.No packet is accepted by receiver side if the CRC fails.5.2Packet HandlingBK2425 uses burst mode for payload transmission and receive.The transmitter fetches payload from TX FIFO, automatically assembles it into packet and transmits the packet in a very short burst period with 1Mbps or 2Mbps air data rate.After transmission, if the PTX packet has the NO_ACK flag set, BK2425 sets TX_DS and gives an active low interrupt IRQ to MCU. If the PTX is ACK packet, the PTX needs receive ACK from the PRX and then asserts the TX_DS IRQ.The receiver automatically validates and disassembles received packet, if there is a valid packet within the new payload, it will write the payload into RX FIFO, set RX_DR and give an active low interrupt IRQ to MCU.When auto acknowledge is enabled (EN_AA=1), the PTX device will automatically wait for acknowledge packet after transmission, and re- transmit original packet with the delay of ARD until an acknowledge packet is received or the number of re-transmission exceeds a threshold ARC. If the later one happens, BK2425 will set MAX_RT and give an active low interruptRevision 1.0Proprietary and Confidential Page 10 of 30BK2425IRQ to MCU. Two packet loss counters (ARC_CNT and PLOS_CNT) are incremented each time a packet is lost. The ARC_CNT counts the number of retransmissions for the current transaction. The PLOS_CNT counts the total number of retransmissions since the last channel change. ARC_CNT is reset by initiating a new transaction. PLOS_CNT is reset by writing to the RF_CH register. It is possible to use the information in the OBSERVE _TX register to make an overall assessment of the channel quality.The PTX device will retransmit if its RX FIFO is full but received ACK frame has payload.As an alternative for PTX device to auto retransmit it is possible to manually set the BK2425 to retransmit a packet a number of times. This is done by the REUSE_TX_PL command.When auto acknowledge is enabled, the PRX device will automatically check the NO_ACK field in received packet, and if NO_ACK=0, it will automatically send an acknowledge packet to PTX device. If EN_ACK_PAY is set, and the acknowledge packet can also include pending payload in TX FIFO.6 Data and Control Interface 6.1TX/RX FIFOThe data FIFOs are used to store payload that is to be transmitted (TX FIFO) or payload that is received and ready to be clocked out (RX FIFO). The FIFO is accessible in both PTX mode and PRX mode.There are three levels 32 bytes FIFO for both TX and RX, supporting both acknowledge mode or no acknowledge mode with up to six pipes.⏹TX three levels, 32 byte FIFO⏹RX three levels, 32 byte FIFOBoth FIFOs have a controller and are accessible through the SPI by using dedicated SPI commands. A TX FIFO in PRX can store payload for ACK packets to three different PTX devices. If the TX FIFO contains more than one payload to a pipe, payloads are handled using the first in first out principle. The TX FIFO in a PRX is blocked if all pending payloads are addressed to pipes where the link to the PTX is lost. In this case, the MCU can flush the TX FIFO by using the FLUSH_TX command.The RX FIFO in PRX may contain payload from up to three different PTX devices.A TX FIFO in PTX can have up to three payloads stored.The TX FIFO can be written to by three commands, W_TX_PAYLOAD and W_ TX_PAYLOAD_NO_ACK in PTX mode and W_ACK_PAYLOAD in PRX mode. All three commands give access to the TX_PLD register. The RX FIFO can be read by the command R_RX _PAYLOAD in both PTX and PRX mode. This command gives access to the RX_PLD register.The payload in TX FIFO in a PTX is NOT removed if the MAX_RT IRQ is asserted.In the FIFO_STATUS register it is possible to read if the TX and RX FIFO are full or empty. The TX_REUSE bit is also available in the FIFO_STATUS register. TX_REUSE is set by the SPI command REUSE_TX_PL, and is reset by the SPI command: W_TX_PAYLOAD or FLUSH TX.6.2InterruptIn BK2425 there is an active low interrupt (IRQ) pin, which is activated when TX_ DS IRQ, RX_DR IRQ or MAX_RT IRQ are set high by the state machine in the STATUS register. The IRQ pin resets when MCU writes '1' to the IRQ source bit in the STATUS register. The IRQ mask in the CONFIGRevision 1.0Proprietary and Confidential Page 11 of 30BK2425register is used to select the IRQ sources that are allowed to assert the IRQ pin. By setting one of the MASK bits high, the corresponding IRQ source is disabled. By default all IRQ sources are enabled.The 3 bit pipe information in the STATUS register is updated during the IRQ pin high to low transition. If the STATUS register is read during an IRQ pin high to low transition, the pipe information is unreliable.6.3SPI Interface6.3.1SPI CommandThe SPI commands are shown in Table 3. Every new command must be started by a high to low transition on CSN.In parallel to the SPI command word applied on the MOSI pin, the STATUS register is shifted serially out on the MISO pin.The serial shifting SPI commands is in the following format:⏹<Command word: MSB bit to LSB bit(one byte)>⏹<Data bytes: LSB byte to MSB byte, MSBbit in each byte first> for all registers atbank 0 and register 9 to register 14 at bank1⏹<Data bytes: MSB byte to LSB byte, MSBbit in each byte first> for register 0 toregister 8 at bank 1Command# DataOperation Command name wordbytes(binary)R_REGISTER 000A AAAA 1 to 5 Read command and status registers. AAAAA = LSB byte first 5 bit Register Map Address1 to 5Write command and status registers. AAAAA = 5W_REGISTER 001A AAAA bit Register Map AddressLSB byte first Executable in power down or standby modes only.1 to 32 Read RX-payload: 1 – 32 bytes. A read operationR_RX_PAYLOAD 0110 0001 always starts at byte 0. Payload is deleted from FIFOLSB byte first after it is read. Used in RX mode.W_TX_PAYLOAD 1010 0000 1 to 32 Write TX-payload: 1 – 32 bytes. A write operation LSB byte first always starts at byte 0 used in TX payload.FLUSH_TX 1110 0001 0 Flush TX FIFO, used in TX modeFlush RX FIFO, used in RX modeFLUSH_RX 1110 0010 0 Should not be executed during transmission of acknowledge, that is, acknowledge package will not be completed.Used for a PTX deviceReuse last transmitted payload. Packets are repeatedly retransmitted as long as CE is high.REUSE_TX_PL 1110 0011 0 TX payload reuse is active untilW_TX_PAYLOAD or FLUSH TX is executed. TX payload reuse must not be activated or deactivated during package transmissionRevision 1.0Proprietary and Confidential Page 12 of 30BK2425 This write command followed by data 0x73 activates the following features:• R_RX_PL_WID• W_ACK_PAYLOAD• W_TX_PAYLOAD_NOACKA new ACTIVATE command with the same data deactivates them again. This is executable in power down or stand by modes only.ACTIVATE 0101 0000 1 The R_RX_PL_WID, W_ACK_PAYLOAD, andW_TX_PAYLOAD_NOACK features registers are initially in a deactivated state; a write has no effect, a read only results in zeros on MISO. To activate these registers, use the ACTIVATE command followed by data 0x73. Then they can be accessed as any other register. Use the same command and data to deactivate the registers again.This write command followed by data 0x53 toggles the register bank, and the current register bank number can be read out from REG7 [7]R_RX_PL_WID 0110 0000 Read RX-payload width for the topR_RX_PAYLOAD in the RX FIFO.Used in RX mode.Write Payload to be transmitted together with ACK packet on PIPE PPP. (PPP valid in the rangeW_ACK_PAYLOAD 1010 1PPP 1 to 32 from 000 to 101). Maximum three ACK packetLSB byte first payloads can be pending. Payloads with same PPP are handled using first in - first out principle. Writepayload: 1– 32 bytes. A write operation always startsat byte 0.W_TX_PAYLOAD_NO1011 0000 1 to 32 Used in TX mode. Disables AUTOACK on thisACK LSB byte first specific packet.NOP 1111 1111 0 No Operation. Might be used to read the STATUS registerTable 2 SPI command6.3.2SPI TimingS C KC S NW r i t e t o S P I r e g i s t e r:M O S I x C 7 C 6 C 5 C 4 C 3 C 2 C 1 C 0 x D 7 D 6 D 5 D 4 D 3 D 2 D 1 D 0 x M I S O H I - Z S 7 S 6 S 5 S 4 S 3 S 2 S 1 S 0 0 0 0 0 0 0 0 0 H i - Z R e a d f r o m S P I r e g i s t e r:M O S I x C 7 C 6 C 5 C 4 C 3 C 2 C 1 C 0 xM I S O x S 7 S 6 S 5 S 4 S 3 S 2 S 1 S 0 D 7 D 6 D 5 D 4 D 3 D 2 D 1 D 0 xFigure 6 SPI timingRevision 1.0Proprietary and Confidential Page 13 of 30BK2425 Cn: SPI command bitSn: STATUS register bitDn: Data Bit (LSB byte to MSB byte, MSB bit in each byte first)Note: The SPI timing is for bank 0 and register 9 to 14 at bank 1. For register 0 to 8 at bank 1, the byte order is inversed that the MSB byte is R/W before LSB byte.Figure 7 SPI NOP timing diagramSymbol Parameters Min Max UnitsTdc Data to SCK Setup 10 nsTdh SCK to Data Hold 20 nsTcsd CSN to Data Valid 38 nsTcd SCK to Data Valid 55 nsTcl SCK Low Time 40 nsTch SCK High Time 40 nsFsck SCK Frequency 0 8 MHzTr,Tf SCK Rise and Fall 100 nsTcc CSN to SCK Setup 2 nsTcch SCK to CSN Hold 2 nsTcwh CSN Inactive time 50 nsTcdz CSN to Output High Z 38 nsTable 3 SPI timing parameterRevision 1.0Proprietary and Confidential Page 14 of 30BK24257 Register MapThere are two register banks, which can be toggled by SPI command “ACTIVATE” followed with0x53 byte, and bank status can be read from Bank0_REG7 [7].7.1Register Bank 0AddressMnemonic Bit ResetType Description(Hex) Value00 CONFIG Configuration RegisterReserved 7 0 R/W Only '0' allowedMASK_RX_DR 6 0 R/W Mask interrupt caused by RX_DR1: Interrupt not reflected on the IRQ pin0: Reflect RX_DR as active low interrupton the IRQ pinMASK_TX_DS 5 0 R/W Mask interrupt caused by TX_DS1: Interrupt not reflected on the IRQ pin0: Reflect TX_DS as active low interrupton the IRQ pinMASK_MAX_RT 4 0 R/W Mask interrupt caused by MAX_RT1: Interrupt not reflected on the IRQ pin0: Reflect MAX_RT as active lowinterrupt on the IRQ pinEN_CRC 3 1 R/W Enable CRC. Forced high if one of the bits in the EN_AA is highCRCO 2 0 R/W CRC encoding scheme'0' - 1 byte'1' - 2 bytesPWR_UP 1 0 R/W 1: POWER UP, 0:POWER DOWNPRIM_RX 0 0 R/W RX/TX control,1: PRX, 0: PTX01 EN_AA Enable ‘Auto Acknowledgment’ FunctionReserved 7:6 00 R/W Only '00' allowedENAA_P5 5 1 R/W Enable auto acknowledgement data pipe 5ENAA_P4 4 1 R/W Enable auto acknowledgement data pipe 4ENAA_P3 3 1 R/W Enable auto acknowledgement data pipe 3ENAA_P2 2 1 R/W Enable auto acknowledgement data pipe 2ENAA_P1 1 1 R/W Enable auto acknowledgement data pipe 1ENAA_P0 0 1 R/W Enable auto acknowledgement data pipe 0 02 EN_RXADDR Enabled RX AddressesReserved 7:6 00 R/W Only '00' allowedERX_P5 5 0 R/W Enable data pipe 5.ERX_P4 4 0 R/W Enable data pipe 4.ERX_P3 3 0 R/W Enable data pipe 3.ERX_P2 2 0 R/W Enable data pipe 2.ERX_P1 1 1 R/W Enable data pipe 1.ERX_P0 0 1 R/W Enable data pipe 0.Revision 1.0 Proprietary and Confidential Page 15 of 30BK2425 03 SETUP_AW Setup of Address Widths(common for all data pipes)Reserved 7:2 000000 R/W Only '000000' allowedAW 1:0 11 R/W RX/TX Address field width'00' - Illegal'01' - 3 bytes'10' - 4 bytes'11' - 5 bytesLSB bytes are used if address width is below 5 bytes04 SETUP_RETR Setup of Automatic RetransmissionARD 7:4 0000 R/W Auto Retransmission Delay‘0000’ – Wait 250 us‘0001’ – Wait 500 us‘0010’ – Wait 750 us……..‘1111’ – Wait 4000 us(Delay defined from end of transmission tostart of next transmission)ARC 3:0 0011 R/W Auto Retransmission Count‘0000’ –Re-Transmit disabled‘0001’ – Up to 1 Re-Transmission on fail of AA……‘1111’ – Up to 15 Re-Transmission on fail of AA05 RF_CH RF ChannelReserved 7 0 R/W Only '0' allowedRF_CH 6:0 0000010 R/W Sets the frequency channel 06 RF_SETUP RF Setup RegisterReserved 7:6 0 R/W Only '00' allowedRF_DR_LOW 5 0 R/W Set Air Data Rate. See RF_DR_HIGH for encoding.PLL_LOCK 4 0 R/W Force PLL lock signal. Only used in testSet Air Data Rate.RF_DR_HIGH 3 1 R/W Encoding: RF_DR_LOW, RF_DR_HIGH: ‘00’ – 1Mbps‘01’ – 2Mbps (default)‘10’ – 250Kbps‘11’ – 2MbpsRF_PWR[1:0] 2:1Set RF output power in TX mode 11 R/W RF_PWR[1:0]Setup LNA gainLNA_HCURR 0 1 R/W 0:Low gain(20dB down)1:High gainStatus Register (In parallel to the SPI07 STATUS command word applied on the MOSI pin,the STATUS register is shifted serially outon the MISO pin)Register bank selection states. SwitchRBANK 7 0 R register bank is done by SPI command “ACTIVATE” followed by 0x530: Register bank 0。
人人都能玩航拍手把手教你装4轴飞行器
人人都能玩航拍手把手教你装4轴飞行器身处浩瀚的影像横流，当看惯了人体大妞、风光美景、人文纪实，面对雷同的构图和取景显然新潮的拍摄手法和技巧更能吸引我的眼球，而当某日看到乔岩老师剪辑的航拍作品，让我深深沦陷，从此欲罢不能。
废话不多说，看视频才是要紧事（视频来源：《旅游卫视》乔岩）。
我相信当看到这段视频你也会如我一样震撼，震撼于这段电影感十足的短片拍摄器材仅仅是一个多轴飞行器的。
当然如果你看到此处觉得航拍是你想涉及和感兴趣的领域那么尽情的往下看，如果并非兴趣所在请绕道，毕竟接下来的故事需要一定的学习能力、理解能力和动手能力。
既然多轴飞行器能拍出这么专业的视频，土豪们会毫不在乎的说那买一个不就完了，其实并非如此，6轴飞行器的成品机造价动辄数万元到数十万元不等，而操控也是个技术活，玩航模的都知道不摔个几次，不坏个几台机器（炸机）想要操控自如谈何容易，所以你还会轻易的任数万元人民币在天上飘来飘去吗？当然土豪有土豪的玩法，屌丝有屌丝的办法。
既然不能一步到位，那我只能脚踏实地从几千元的组装4轴开始，搭载运动摄像机Gopro 的拍摄效果虽说不比专业6轴细致震撼，却也能满足一般所需。
四轴组装基本原理和零件选购：1、4轴飞行器原理和组成：虽然看似神通广大的高科技产品，其实原理非常非常简单，而所需的零件在某宝上完全可以买到，只需要把他们有序的组装起来，并保障起正常运转。
玩转航拍并不再是一个遥不可及的梦想，只要动手就变的容易实现.4轴飞行器的基本配件由机架、电池、电机、电调、飞控、螺旋桨、遥控器、拍摄相机（gopro、摄像头、微单等）组成，原理为遥控器发射遥控型号，遥控接收器收到信号传输给飞控（飞行控制器，等同于电脑的主板），飞控将遥控信号转化传输给电调，电调调节不同电机的供电电流以控制螺旋桨的旋转速度从而完成前后左右，高低上下的飞行动作，而电池负责供电，机架将所有的零件攥在一起,这样飞行器就能带拍摄机器完成在空中的各种拍摄需求。
四轴飞行器原理教程
第三章四轴飞行器程序设计
电池越重。基本原理是用大桨，因为整体搭配下来功率高，自身升力大，为了 保证可玩时间，可选高容量，高 C，3S 以上电池。最低建议 2200mAh，20C，3S。 小四轴，因为自身升力有限，整体功率也不高，就可以考虑小容量，小 C，3S 以下电池。 平衡充电什么意思 ？ 如 3S 电池，内部是 3 个锂电池，因为制造工艺原因，没办法保证每个电池完全
算法总结 姿态解算得 到姿态角 遥控器设 定目标
姿态解算
整个姿态解算的原理是：由于加速度计噪声误差和陀螺仪积分误差，导致测 得的机体坐标系不准，得到的姿态也就会不准确。因为地理坐标系中飞行器所受 的重力和磁场是个常量，如果将它们转换到机体坐标系中，转换后的重力向量和 磁场向量与实际测量的向量会有误差，只要消除此误差，就可以校正机体坐标系 得到准确的姿态。消除误差采用PI互补滤波，姿态表示用四元数（a+bi+cj+dk， 且 ） 姿态角通过串级PID控制电机转速
2.4无刷电机与螺旋桨篇
电机分为有刷电机和无刷电机，无刷是四轴的主流，它力气大，耐用，有刷电 机就是我们所说的马达，用于微型四轴。
电机的型号含义？ 说什么 2212 电机，2018 电机等等， 到底是什么意思呢？这其实电机的 尺寸。不管什么牌子的电机，具体 都要对应 4 位这类数字，其中前面
2 位是电机转子的直径，后面 2 位
飞行动作
姿态解算算法的实现步骤为：
* 将滤波后的三轴加速度计值归一化，该值为机体坐标系下重力向量的测量值
* 将地理坐标系的重力向量转换到机体坐标系中
* 将地理坐标系转换到机体坐标系下的重力向量与机体坐标系测量的向量外积
（叉积），得到的就是两坐标系的误差。
四轴结构s
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1、遥控器 什么是通道？ 通道就是可以遥控器控制的动作路数，比如遥控器只能 控制四轴上下飞，那么就是1个通道。但四轴在控制过程中 需要控制的动作路数有：油门、俯仰、升降、航向
当你充满电的电池，不能满电保存超过3天，如果超过一个 星期不放掉，有些电池就直接鼓包了，有些电池可能暂时 不会 鼓，但几次满电保存后，电池会直接挂掉。 正确的方式是，准备飞之前才充电，如果因各种原因没飞， 也要在充满后3天内找时间把电池放电到3.9V。如 果电池 长久不用，要将电池放电到单片3.85V的保存电压。 2017/5/2 26
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（4）飞行控制板 （常见开源飞控Pixhawk,APM,MWC。土豪飞控: 大疆系列。低级别的有QQ、KK、玉兔等品牌）
Pixhawk
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APM
DJI NAZA系列
22
QQ飞控
MWC
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KK飞控
23
（5）电池（航模锂动力电池）
关于航模锂动力电池的保养技巧 航模锂聚电池是有寿命的，如何延长电池寿命？ 最重要的是新电池的激活以及平时的使用维护方 法。
偏 航 运 动
前 后 运 动
（5）前后运动：（与俯仰运动相同）要想实现飞行器在水平面内 前后、左右的运动，必须在水平面内对飞行器施加一定的力。在 图 e中，增加电机 3转速，使拉力增大，相应减小电机 1转速，使 拉力减小，同时保持其它两个电机转速不变，反扭矩仍然要保持 平衡。按图 b的理论，飞行器首先发生一定程度的倾斜，从而使旋 翼拉力产生水平分量，因此可以实现飞行器的前飞运动。向后飞 2017/5/2 13 行与向前飞行正好相反。
【创客】手把手教你DIY四轴无人飞行器（建议收藏！）
【创客】⼿把⼿教你DIY四轴⽆⼈飞⾏器（建议收藏！）很多DIY爱好者想做⼀个⾃⼰的⽆⼈机，但很多⼈都被制作过程中的各种问题难住。
不去研究复杂的算法和硬件，也能做出⾃⼰满意的⽆⼈飞⾏器？那么你就来对地⽅了！现在，我们从零开始⼿把⼿教你DIY四轴⽆⼈飞⾏器！DIY制作的四轴飞⾏器配置清单：1.四轴机架（轴距450mm）2.中⼼沉⾦PCB板3.好盈天⾏者30A⽆刷电调4.朗宇2212⽆刷电机（980KV）5.3200mah锂电池（30C）6.APM2.8开源飞控7.M8N GPS8.BB响（低压报警器）9.减震架10.MR 1045(1047)正反螺旋桨11.电流计12.⾹蕉头，T插，⾼温硅胶线材等若⼲⼩零件⾸先普及⼀下基础知识⼩葵花课堂1.⽆刷电机（图为有刷电机）我们⼩时候玩的四驱车⾥⾯的马达⼀般都是直流有刷电机，有刷电机⼯作时，线圈和换向器旋转，磁钢和碳刷不转，线圈电流⽅向的交替变化是随电机转动的换相器和电刷来完成的，简单来说，就是通过电刷改变线圈的电磁场⽅向，因此有刷电机是可以直接使⽤直流电驱动。
顾名思义，⽆刷电机是没有电刷的，它只能通过⽅向交替的电流来改变电磁场，因此⽆刷电机需要电调（电⼦调速器）将直流电转化为交流电才能正常⼯作。
（图为⽆刷电机）航模通常使⽤⽆刷电机，⽆刷电机相对来说可以容易达到很⾼的速度，响应速度也会更快。
⽆刷电机去除了电刷，最直接的变化就是没有了有刷电机运转时产⽣的电⽕花，这样就极⼤减少了电⽕花对遥控⽆线电设备的⼲扰。
这次我使⽤的是朗宇的电机（建议不要使⽤新西达的电机和电调，质量太烂）。
选⽤的980KV的电机配MR 1045或1047的螺旋桨（MR指四轴专⽤桨）。
其中，KV值是挑选⽆刷电机的⼀个重要指标。
⽆刷电机KV值定义为转速/V，意思为输⼊电压增加1伏特，⽆刷电机空转转速增加的转速值。
从这个定义来看，我们能知道，⽆刷电机电压的输⼊与电机空转转速是遵循严格的线性⽐例关系的。