（二）树莓派小车控制系统和实时视频传输的实现

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我是靠谱客的博主平常宝贝，这篇文章主要介绍（二）树莓派小车控制系统和实时视频传输的实现，现在分享给大家，希望可以做个参考。

前言

上一篇文章介绍了我们需要准备什么东西。具体的组装我就不在多介绍了，这是我组装好的样子。
原件购买的话可以先在闲鱼逛一逛，一些学长毕业以后会把自己用完的东西挂在那里。

这是水弹枪的样子，淘宝有卖的，很多部件是3D打印的，如果你有打印机的话，可以找找模型自己打印。只要通电就可以连续发射水弹，通电时电流很大，所以我们需要用一个继电器来控制这个水弹枪。当然这都是后话了，我们首要任务是先让小车跑起来，然后再去添加这些花里胡哨的功能。

代码

为了更简单，我用了Flask框架做服务端。为了让代码更易懂。用面向对象的概念，把轮子类实现。

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import RPi.GPIO as GPIO
SPEED = 50   #用来控制速度，pwm占空比
FREQUENCY = 6000 #pwm频率
CW = 1
CCW = 0
class Wheel:
    def __init__(self, speed_pin, direction_pin,isStop_pin):
        self.pin_speed = speed_pin
        self.pin_direction = direction_pin
        self.pin_isStop = isStop_pin
        self.isStop = True
        self.speed = SPEED
        self.direction = CW
        GPIO.setup(self.pin_speed,GPIO.OUT)
        GPIO.setup(self.pin_direction, GPIO.OUT)
        GPIO.setup(self.pin_isStop, GPIO.OUT)
        GPIO.output(self.pin_isStop, False)
        self.pwm = GPIO.PWM(self.pin_speed,FREQUENCY)
        self.pwm.start(SPEED)

def stop(self):
        GPIO.output(self.pin_isStop,False)
        self.isStop = True

def cw(self):
        GPIO.output(self.pin_isStop, True)
        GPIO.output(self.pin_direction,True)
        self.direction = CW
        self.isStop = False

def ccw(self):
        GPIO.output(self.pin_isStop,True)
        GPIO.output(self.pin_direction,False)
        self.direction = CCW
        self.isStop = False

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import RPi.GPIO as GPIO
SPEED = 50   #用来控制速度，pwm占空比
FREQUENCY = 6000 #pwm频率
CW = 1
CCW = 0
class Wheel:
    def __init__(self, speed_pin, direction_pin,isStop_pin):
        self.pin_speed = speed_pin
        self.pin_direction = direction_pin
        self.pin_isStop = isStop_pin
        self.isStop = True
        self.speed = SPEED
        self.direction = CW
        GPIO.setup(self.pin_speed,GPIO.OUT)
        GPIO.setup(self.pin_direction, GPIO.OUT)
        GPIO.setup(self.pin_isStop, GPIO.OUT)
        GPIO.output(self.pin_isStop, False)
        self.pwm = GPIO.PWM(self.pin_speed,FREQUENCY)
        self.pwm.start(SPEED)

    def stop(self):
        GPIO.output(self.pin_isStop,False)
        self.isStop = True

    def cw(self):
        GPIO.output(self.pin_isStop, True)
        GPIO.output(self.pin_direction,True)
        self.direction = CW
        self.isStop = False

    def ccw(self):
        GPIO.output(self.pin_isStop,True)
        GPIO.output(self.pin_direction,False)
        self.direction = CCW
        self.isStop = False

进而，我们一个小车有四个轮子，可以实现小车类

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from wheel import  Wheel
import RPi.GPIO as GPIO
import wheel
#0:speed 1:direction 2:stop
class Car:
    def __init__(self,FrL_,FrR_,BeL_,BeR_):
        GPIO.setmode(GPIO.BOARD)
        self.wheelFrL = Wheel(FrL_[0],FrL_[1],FrL_[2])
        self.wheelFrR = Wheel(FrR_[0],FrR_[1],FrR_[2])
        self.wheelBeL = Wheel(BeL_[0],BeL_[1],BeL_[2])
        self.wheelBeR = Wheel(BeR_[0],BeR_[1],BeR_[2])

    def moveFront(self): #小车向前移动
        self.wheelFrL.ccw() #左前轮逆时针
        self.wheelBeR.cw()	#右后轮顺时针
        self.wheelBeL.ccw() #左后轮逆时针
        self.wheelFrR.cw()  #右前轮顺时针

    def moveBehind(self):
        self.wheelFrL.cw()
        self.wheelBeR.ccw()
        self.wheelBeL.cw()
        self.wheelFrR.ccw()
#

完整代码以后会打包贴出来，这里注意麦克纳姆轮的安装方式，我采用的是米字安装，每个电机互相配合，小车整体就会做出相应的动作。

最后要实现服务端，顺便把要显示摄像头实时画面的部分完成：

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from flask import Flask
from flask import Flask, render_template, Response
import cv2
from car import Car
FrL=[7,11,13] # red blue yellow 每个轮子的三条信号线要接的引脚号
FrR=[15,29,31] 
BeL=[33,35,37]
BeR=[12,16,18]
class VideoCamera(object):
    def __init__(self):
        self.cap = cv2.VideoCapture(0)

def __del__(self):
        self.cap.release()

def get_frame(self):
        success, image = self.cap.read()
        ret, jpeg = cv2.imencode('.jpg', image)
        return jpeg.tobytes()

app = Flask(__name__)

@app.route('/')
def hello_world():
    return render_template('index.html')

def gen(camera):
    while True:
        frame = camera.get_frame()
        yield (b'--framern'
               b'Content-Type: image/jpegrnrn' + frame + b'rnrn')

@app.route('/video_feed')
def video_feed():
    return Response(gen(VideoCamera()), mimetype='multipart/x-mixed-replace; boundary=frame')

@app.route('/front')
def front():
    car.moveFront()
    print('front') #just for debug
    return 'ok'
@app.route('/behind')
def behind():
    car.moveBehind()
    print('behind')
    return 'ok'
@app.route('/left')
#完整代码不贴了
# @app.route('/cameraLeft') #摄像头云台移动 还未完善
# @app.route('/cameraRight')
# @app.route('/cameraUp')
# @app.route('/cameraDown')

if __name__ == '__main__':
    car = Car(FrL,FrR,BeL,BeR) #实例化一个小车
    app.run()

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from flask import Flask
from flask import Flask, render_template, Response
import cv2
from car import Car
FrL=[7,11,13] # red blue yellow 每个轮子的三条信号线要接的引脚号
FrR=[15,29,31] 
BeL=[33,35,37]
BeR=[12,16,18]
class VideoCamera(object):
    def __init__(self):
        self.cap = cv2.VideoCapture(0)

    def __del__(self):
        self.cap.release()

    def get_frame(self):
        success, image = self.cap.read()
        ret, jpeg = cv2.imencode('.jpg', image)
        return jpeg.tobytes()

app = Flask(__name__)

@app.route('/')
def hello_world():
    return render_template('index.html')

def gen(camera):
    while True:
        frame = camera.get_frame()
        yield (b'--framern'
               b'Content-Type: image/jpegrnrn' + frame + b'rnrn')

@app.route('/video_feed')
def video_feed():
    return Response(gen(VideoCamera()), mimetype='multipart/x-mixed-replace; boundary=frame')

@app.route('/front')
def front():
    car.moveFront()
    print('front') #just for debug
    return 'ok'
@app.route('/behind')
def behind():
    car.moveBehind()
    print('behind')
    return 'ok'
@app.route('/left')
#完整代码不贴了
# @app.route('/cameraLeft') #摄像头云台移动 还未完善
# @app.route('/cameraRight')
# @app.route('/cameraUp')
# @app.route('/cameraDown')

if __name__ == '__main__':
    car = Car(FrL,FrR,BeL,BeR) #实例化一个小车
    app.run()