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基于单片机的电动智能小车通过研发实现了一种以光电传感器为敏感元件，以 AT89C51 单片机为控制核心的电动循迹小车的智能控，该系统还包括直流电机、L9110 芯片和 LM324 比较器等。本设计采用 AT89C51 单片机作为智能小车核心控制器。本系统以单片机为控制核心 ,实现电动车的前进、退、左转和右转功能.通过角度传感器 1 检测跷跷板角度的变化 ,利用增量式 PI算法 2 控制电动车寻找平衡点 ,同时运用光电传感器检测黑线 ,使电动车在行驶过程中保持直线运动且不会脱离跷跷。一方案设计电动车的速度、位置、运行状况的实时测量 ，并将测量数据传送至单片机进行处理，然后由单片机根据所检测的各种数据实现对电动车的智能控制。这种方案能实现对电动车的运动状 态进行实时控制，控制，灵活可靠 ，精度高 ，可满足对系统的各项要求。(1)直流调速系统直流调速系统采用脉宽调速系统，其主电路采用脉宽调制式变换器，简称PWM变换器。由于PWM调速 系统的开关频率较高，仅靠电枢电感的滤波作用就可以获得脉动很小的直流电流，电枢电流容易 连续，系统的低速运行平稳，调速范围较宽，可达1：10000左右。 由于电流波形比 V-M系统好，在相同的平均电流下，电动机的损耗和发热都比较小。同样由于开关频率高，若与快速响应的电机相配合，系统可以获得很宽的频带，因此快速响应性能好，动态抗扰能力强。根据以上综合 比较，以及本设计中受控电机的容量和直流电机调速的发展方向，本设计采用了H型单极型可逆 PWM变换器进行调速。1.1 光电检测模块设计该智能小车在贴有黑线的白纸“路面”上行驶，因此本模块设计需要检测铺在行驶区 的 黑 胶 带，包 括直线行驶区和沿弧线行驶区两个区域。由于黑线和白纸对光线的反射系数不同可根据接收到的反射光的强弱来判断“道路”-黑线。本文采用的是简单实用的检测方法，即红外探测法。红外探测法，即利用红外线在不同颜色的物理表面具有不同的反射性质的特点。在小车行驶过程中不断地向地面发射红外光，当红外光遇到白色地面时发生漫发射，反射光被装在小车上的接收管接收； 如果遇到黑线则红外光被吸收，则小车上的接收管接收不到信号。1.2 信号比较模块设计输送给单片机，用于检测传感器的敏感性，电路图如图 5 所示。当两个传感器同时检测到光时，直线前进。当传感器检测不到光时，处于截止状态，双运算放大器 LM324 输出低电平给单片机，由程序处理； 若左路未检测到光，则向左纠正方向； 若右路未检测到光，则向右纠正方向。1.3 电机控制与驱动模块设计由于采用的是双驱动的小车，这部分电路必须能够输出两个不同的电压值，分别去控制小车的左、右两个驱动电机，使小车的两个车轮的转速和方向相同或不同，从而来控制它的前进和转弯。在系统的设计过程中，用两个 L9110 芯片来分别连接单片机和直流电机。L9110 是为控制和驱动电机设计的两通道推挽式功率放大专用集成电路器件，将分立电路集成在单片 IC 之中，使外围器件成本降低，整机可靠性提高。该芯片有两个 TTL / CMOS 兼 容 电 平 的 输 入，具 有良好的抗干扰性； 两个输出端能直接驱动电机的正反向运动，它具有较大的电流驱动能力，每通道能通过800mA 的持续电流，峰值电流能力可达 1.5 2.0A； 同时它具有较低的输出饱和压降与静态电流； 内置的钳位二极管能释放感性负载的反向冲击电流，使它在驱动继电器、直流电机、步进电机或开关功率管的使用上安全可靠。循迹小车系统以常见的 AT89C51 单片机为核心，辅以较简单的元器件和电路设计，在顺利完成循迹功能的前提下，又充分考虑到了外观、成本等问题，因此小车的大部分电路由手工焊接完成。在设计中，我们没有在电路中增加冗余的功能，但是保留了各种硬件接口和软件子程序接口，方便以后的扩展和开发。二 系统硬件设计2. 1 电机驱动模块设计在制作智能小车时, 后左、右轮分别用两个转速和力矩基本完全相同的直流减速电机进行驱动, 车头前部装一个方向轮, 然后通过 I/O 口控制两个直流减速电机的转速和转向就可以实现小车的左转、右转和直行。电机驱动 采用 一片 集成电机驱动芯片L 298N。L298N是ST公司的产品, 内部包含 4通道逻辑驱动电路, 是一种二相和四相电机的专用驱动器, 即内含二个H 桥的高电压大电流双全桥式驱动器, 接收标准 TTL逻辑电平信号, 可驱动 46V、2A 以下的电机。2. 2 寻迹模块设计寻迹模块主要由光电反射式传感器组成。光敏电阻的阻值随周围环境光线的变化而变化, 当光线照射到白线上面时, 光线发射强烈; 光线照射到黑 线上面时, 光线发射较弱。因此当光敏电阻在白线和黑线上方时, 阻值会发生明显的变化, 将阻值的变化值经过比较器就可以输出高低电平。但是这种方式受环境影响大, 工作不稳定。本文实际采用的是 RPR220 型反射式传感器制作的寻迹模块。RPR220是一种一体 化反射型光电探测器, 其发射器是一个砷化镓红外发光二极管, 而接收器是一个高灵敏度硅平面光电三极管。当发光二极管发出的光反射回来时, 三极管导通并输出低电平。2. 3 避障模块设计避障模块主要由红外反射式传感器组成。红外反射式传感器由 1 个红外发射管 (发射器 )和 1个光电二极管 (接收器 )构成, 红外发射管发出的红外光在遇到反光性较强的物体后被折回, 被光电二极管接收, 引起光电二极管光生电流的增大, 将此变化转为电压信号, 就可以被处理器接收并处理。2. 4 遥控模块设计本模块发射端采用高灵敏的 H L - 5000型万能电视遥控器, 接收端采用接收频率为 38kH z的万能接收头 1838, 该模块与单 片机接口非常方便。另外, 对于经 红 外 接 收 后 的 编 码 信 号, 本系统设计时运用AT89C52单片微机的外部中断来接收, 信号的下降沿触发外部中断。为了识别一个完整的键信号, 必须对每一个编码脉冲的宽度进行测量, 以判别接收到的脉是 ! 0还是 ! 1, 利用单片机中的定时器 /计数器来测量脉冲宽度。定时器 /计数器的除分比是可以设定的, 从除 2到除 2048, 可测量的脉冲宽度可达 500m s。本文设定的除分比为 12, 即 12分频, 因为外部时钟约为 12MH z, 时钟周期为 1 s, 所以定时器 /计数器每计时一次为 1 s。2. 5 报警模块设计报警模块的核心芯片选择 110报警 IC, 可应用于汽车、摩托车、防盗器、个人防暴器、门磁报警 器等场所。三 系统软件设计本系统软件采用模块化结构, 由主程序初始化子程序、中断子程序、延时子程序、按键发音子程序、按键扫描子程序构成。3. 1 寻迹子程序设计寻迹模块设计是通过把左 右光电传感器 的输出端分别接到单 片机的 P 22 和 P23 管脚 上, 然后 通过单片机编程, 产生 PWM 控制信号, 通过 L 298控制电机的转速, 让小车达到前进、左转、右转及停止行驶的目的。3. 2 避障子程序设计避障模块设计是通过把左右红外反射式传感器模块的输出端分别接到单片机的 P20和 P21管脚上, 然后通过 单片机编程, 产生 PWM 控制信号, 通过 L298控制电机的转速, 让小车达到前进、左转、右转及停止行驶的目的。3. 3 遥控子程序设计遥控模块设计是通过把红外接收头 1838的输出端接到单片机的 P32管脚上, 然后用万能遥控器对其进行遥控, 接着让单片机解码, 产生 PWM 控制 信号,通过 L298控制电机的转速, 让小车达到前进、左转、右转及停止行驶的目的。四总结采用单片机为核心, 利用光电传感器和红外反射式传感器作为探测系统, 设计了可以实现自动寻线行走、自动避障、报警以及遥控等功能的智能小车。该设计的显著优点是电路简单、可靠性强、成本低, 并且非常易于功能进一步完善和扩展。Electric intelligent car based on SCM Through research and to realize a photoelectric sensor for sensitive components, with AT89C51 as control core electric tracing of intelligent control carbonylation-the car，The system is also including dc motor, L9110 chips and LM324 comparator etc. The design USES AT89C51 as intelligent car core controller。The system takes microcontroller as control core and realization of electric before Enter, back, turn left and right turn function. Through the Angle sensor 1 detection The seesaw Angle change, use incremental PI algorithm 2 to control the electric Car for balance, and using photoelectric sensor detection black line, make the electricity Actuation vehicle in the course of driving keep linear motion and dont skip from atrium。1.Project Designlight by a sensor, the reality of the electric car is moving quickly degrees, bit, buy, transportation line shape when measured quantity of real condition, and will be measured quantity number according to preach sent to monolithic machine into line processing, but by single chip machine according to the measured by root different forms of several inspection according to real now to electric actuation vehicle wisdom can control system. This kind of square case can real now to electric actuation vehicle dynamic shape state into the shipment do real possession in system, control system spirit alive, can depend, pure degree is high, can full foot of each item of the stockings to beg. (1) straight epidemiological speed is tasseled straight epidemiological speed department with pulse width modulation experience.meanwhile gather speed is experience.meanwhile, its main electrical pulse width modulation by road system type variable change device, Jane says PWM variable change device. Adjustable speed by in the department of PWM experience.meanwhile open shut frequency rate is high, only on electricity barnado electricity sense of filter wave can be use to get to move very small straight pulse electric flow, electricity flow barnado electric capacity easily even tantras, department of low speed operation flat experience.meanwhile, adjustable speed stability van is surrounded relatively wide, can reach 1 000 left right. By on electrical flow wave shape than V - M system, be in phase with flat to all electrical flow dynamic machine, electric heat consumption and hair loss than a small. With the sample by in open shut frequency rate is high, and if a fast speed of electrical machine ring should match close, fasten tasseled phase can be to get very wide frequency band, because of the fast speed ring should be good, dynamic configuration sexual can perturbation resistance can force is powerful. According to the root, with more than ensemble close and this set of electrical machine control project by tolerance of the quantity and electrical machine speed straight flow of hair, the exhibitor to adopt the project with a single extremely H type can be changed into change device inverse PWM line speed.1.1 photoelectric detection module designThe intelligent car was stuck on the black line running on white paper road, so this module design need to detect shop on the black rubber belt drive area, including Run straight along the arc district and driving district two area. Because of the black and white paper to light reflection coefficient is different, can according to receive reflected light.The strength of the judge road - the black line. This paper USES is simple and practical detection methods, namely the infrared detection method. Infrared detection method, i.e. use infrared ray in different colors of physical surface with different reflection properties characteristics. In the car driving process Continually to the ground to launch the infrared, when the infrared met white ground occurs when the reflected light, aimless and launch packed on the car of receiving tube receiving; if Fruit is met black line is absorbed, and then the infrared cars receiving tube receiving less than signal.1. 2 signal comparative module designThis part design USES a LM324 comparator, of sensor signal voltage received compare and amplified, and will compare the results after Feed to the microcontroller, used to detect sensor sensitivity, diagram shown in figure 5 shows. When two sensors simultaneously detect light, straight forward. When the sensor cant detect light, in cut-off state, double LM324 operational amplifier output low level to microcontroller, by program processing, If left Not detected light, then left correct direction; If the right has not been detected light, then turn correct direction.1. 3 motor control and driving module designBecause use is double drive cars, this part of the circuit must be able to output of two different voltage values, respectively to controlling trolley right and left two motor drive, the two of the wheel speed and direction of the same or different, thus to control its advance and turning. In system design process, use two L9110 chips to connect SCM and dc motor respectively. L9110 is for control and drive motor design two channels push-pull power amplifier application-specific integrated circuit device, discrete circuits in monolithic IC integrated such that the peripheral equipments in lower cost and the whole machine can carry on sexual high. The core slice two a TTL/CMOS and let electricity flat lose into, have good anti-jamming, Two output terminal can pick flooding dynamic electric machine straight to the shipment of positive reverse move and it has had a big electricity flow flooding dynamic can force, each call way can pass over 800mA continuous current, peak current capacity of 1. 5 0A; 2. At the same time it has lower output saturation pressure drop and the static electricity, The built-in clamp a diode can release the perceptual load of reverse current impulse, making it the drive relays, dc motors, stepping motor or switch power tube the use of safe and reliable.Follow tracing car system to common AT89C51, complementary with relatively simple components and circuit design, the smooth completion of follow under the premise of tracing function, and fully considered appearance, costs, so most of the circuit car by manual welding is complete. In the design, we never in a circuit increase redundant functions, but retained various hardware interface and software subroutines interface to facilitate the expansion and development after.2. System hardware design2. 1 motor driver module designIn making intelligent car, after left, right wheel respectively with two speed and Torque basic identical dc motor driven deceleration, bolt-on trunk-lid spoiler Department to install a direction wheel, then through the I/O mouth to control two dc slowing down Motor speed and steering can be achieved on the car to the left, turn right and straight Line.Motor driver using a integrated electrical machine flooding dynamic core slice L 298N. L298N is ST the product of the company, the internal containing four channel logical drive circuit, it is a kind of two phase four phase motor drive, namely the special contains two H bridge of high voltage large current commander bridge type drive, acceptance criteria TTL logic level signals, be driven 46V, 2A below the motor.2. 2 tracing module designTracing module mainly composed by photoelectric sensor reflex. Photoconductive resistance of the resistance of the light with the surrounding environment changes, when the LTT white lines above, light emission strongly; The LTT black line above, light emission are relatively weak. So when photoconductive resistance in white line and black line above the elements will occur significantly changes, the resistance changes value after comparator can output high level. But this way environmental influences big, work is not stable. This article actual use is RPR220 type reflex sensors made tracing module.RPR220 is an integration of reflective photoelectric detector, the transmitter is a gaas infrared light emitting diode and the receiver is a high sensitivity silicon photoelectric triode flat. When the light emitting diode reflected back, triode conduction and output low level.2. 3 obstacle avoidance module designObstacle avoidance module mainly composed by infrared reflection sensor. Infrared reflection sensor by one infrared tubes (launchers) and 1 photoelectric diode (receiver) constitute, infrared tubes out to meet the infrared object reflective sex strong after be turned back, by photoelectric diode receiving, cause photoelectric diode current increases, light born this change into voltage signal, it could be processor receives and processing.2. 4 remote control module designThis module will launch end USES high sensitive H L - 5000 type universal television remote control, the receiver using receive frequency for 38kH zs receiving head 1838, this module and the single chip computer interface is very convenient. In addition, for the red outside meet after harvest of plait code letter number, the department tasseled set when shipped with project of AT89C52 single chip microcomputer external interruption to receive, signal the falling edge of trigger external interruption. In order to recognize a complete key signal, must for each coding pulse width were measured with discriminant receives the pulse is! 0 still! 1 , the microcontroller timer/counter to measuring pulse width. Timer/counter except points than can be set, from except 2 to except 2048, measurable pulse width can reach 500m s. This paper set except points for 12, namely than 12 points frequency, because the external clock is about 12MH z, clock cycle for 1 s, so the timer/counter for 1 per timing once s.2. 5 alarm module designAlarm module core chip 110 IC, can choose application in automobile, motorcycle, alarms, personal riot device, door magnetic alarm device and etc.3. System software designThis system software modular structure, the main program, initial anti-fuzzy procedures, interrupt subroutines, delay subroutines, buttons pronunciation subroutines, buttons scanning subroutines constitutes.3. 1 tracing subroutines designTracing module is designed by the left right photoelectric sensor output terminal receiving monolithic machine respectively, P 22 and P23 tube feet, then through the microcontroller programming, produce PWM control signal, through L 298 control motor speed, let the car to move forward, left turn, turn right and stop driving purpose.3. 2 avoid barrier of programmingObstacle avoidance module is designed by the infrared reflection sensor module around the output terminal receiving MCU respectively P20 and P21 tube feet, then through the microcontroller programming, produce PWM control signal, through L298 control motor speed, let the car to move forward, left turn, turn right and stop driving purpose.3. 3 remote subroutines designRemote control module is designed by the infrared sensor 1838 an output terminal of the receiving MCU P32 tube feet, then use all-purpose remote control on the remote control, then let microcontroller decoding, produce PWM control signal, through L298 control motor speed, let the car to move forward, left turn, turn right and stop driving purpose.4 Summary Adopts singlechip, using photoelectric sensor and infrared reflection sensor was designed as a detection system, can realize automatic homing line to walk, automatic obstacle avoidance, alarm and remote control functions such as intelligent car. This design is the obvious advantages of simple circuit, reliability, low cost, and very easy to function of further perfecting and expansion
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