一：首先设计小车的驱动模块
由于设计的小车的运动控制是由控制器控制电机执行，但是控制器的IOS口一般只能提供5MA到10MA的电流，而小车直流电机工作电流一般是200-400MA甚至更大，所以控制器直接驱动电机是驱动不了的，需要使用电机驱动电路来放大电流，并且实现前后转动。家庭智宝采用L298P作为直流电机驱动芯片。L298P由ＳＴ公司开发和制造，具有集成高达46V的工作电压，高达3A的瞬时峰值电流和高达25W的额定功率的能力。此外，双通道全桥电动机驱动器芯片可以连接到标准TTL逻辑高电平和低电平，并且可以驱动感性负载。一个L298P可以直接驱动２个直流电动机.由两组L298P驱动电路来驱动循迹避障小车的４个直流电机进行旋转，主控芯片输出电机控制信号给L298P芯片的信号输入脚，进而控制电机的正反转，转动速度等功能。图1-1所示为电机驱动电路设计。
图1-1 驱动电机的L298P电机驱动电路图设计
接着使用嘉立创打板。图1-2实物效果
图1-2 实物效果
二：WIFI联网
详情参考WiFi联网-全志XR806开发板入门教程
主要就是：hm net sta connect < ssid > < psk >：连接指定热点，在没有进行搜索的情况下默认加密方式为WPA/WPA2，如果连接不上，可以尝试先扫描再连接，开发热点不需要填psk。
三：Python编写代码
Ubuntu自带Python，Python有问题的看看官方解决办法。
一般车辆的状态包括：前进、后退、左转、右转、和速度控制五个状态。智能驾驶电动小车由于是计算机控制，所以还需设置紧急制动动作。底层控制系统接收路径规划层发出的指令，实时控制电动小车的运动状况，而紧急制动动作是由紧急制动命令直接控制，具备最高优先级，而前进、后退、左转、右转和速度控制具有相同的优先级。本次设计的智能电动小车的底层控制是由树莓派来实现，因此规定电动小车的三种状态：前进为１、停车为０、倒车为-1，路径规划层发送的命令，正速度为期望状态１，负速度为期望状态-1，速度为零为期望状态０。小车速度通过PWM控制。具体代码如下：
import RPi.GPIO as GPIO
import time
import configparser
LEFT\_FRONT\_1 = 7
LEFT\_FRONT\_2 = 11
RIGHT\_FRONT\_1 = 13
RIGHT\_FRONT\_2 = 15
LEFT\_BEHIND\_1 = 31
LEFT\_BEHIND\_2 = 33
RIGHT\_BEHIND\_1 = 35
RIGHT\_BEHIND\_2 = 37
class FourWheelDriveCar():
def \_\_init\_\_(self):
'''
1. Read pin number from configure file
2. Init all GPIO configureation
'''
config = configparser.ConfigParser()
config.read("config.ini")
self.LEFT\_FRONT\_1 = config.getint("car", "LEFT\_FRONT\_1")
self.LEFT\_FRONT\_2 = config.getint("car", "LEFT\_FRONT\_2")
self.RIGHT\_FRONT\_1 = config.getint("car", "RIGHT\_FRONT\_1")
self.RIGHT\_FRONT\_2 = config.getint("car", "RIGHT\_FRONT\_2")
self.LEFT\_BEHIND\_1 = config.getint("car", "LEFT\_BEHIND\_1")
self.LEFT\_BEHIND\_2 = config.getint("car", "LEFT\_BEHIND\_2")
self.RIGHT\_BEHIND\_1 = config.getint("car", "RIGHT\_BEHIND\_1")
self.RIGHT\_BEHIND\_2 = config.getint("car", "RIGHT\_BEHIND\_2")
GPIO.setmode(GPIO.BOARD)
GPIO.setwarnings(False)
GPIO.setup(self.LEFT\_FRONT\_1, GPIO.OUT)
GPIO.setup(self.LEFT\_FRONT\_2, GPIO.OUT)
GPIO.setup(self.RIGHT\_FRONT\_1, GPIO.OUT)
GPIO.setup(self.RIGHT\_FRONT\_2, GPIO.OUT)
GPIO.setup(self.LEFT\_BEHIND\_1, GPIO.OUT)
GPIO.setup(self.LEFT\_BEHIND\_2, GPIO.OUT)
GPIO.setup(self.RIGHT\_BEHIND\_1, GPIO.OUT)
GPIO.setup(self.RIGHT\_BEHIND\_2, GPIO.OUT)
def reset(self):
# Rest all the GPIO as LOW
GPIO.output(self.LEFT\_FRONT\_1, GPIO.LOW)
GPIO.output(self.LEFT\_FRONT\_2, GPIO.LOW)
GPIO.output(self.RIGHT\_FRONT\_1, GPIO.LOW)
GPIO.output(self.RIGHT\_FRONT\_2, GPIO.LOW)
GPIO.output(self.LEFT\_BEHIND\_1, GPIO.LOW)
GPIO.output(self.LEFT\_BEHIND\_2, GPIO.LOW)
GPIO.output(self.RIGHT\_BEHIND\_1, GPIO.LOW)
GPIO.output(self.RIGHT\_BEHIND\_2, GPIO.LOW)
def \_\_forword(self):
self.reset()
GPIO.output(self.LEFT\_FRONT\_1, GPIO.HIGH)
GPIO.output(self.LEFT\_FRONT\_2, GPIO.LOW)
GPIO.output(self.RIGHT\_FRONT\_1, GPIO.HIGH)
GPIO.output(self.RIGHT\_FRONT\_2, GPIO.LOW)
GPIO.output(self.LEFT\_BEHIND\_1, GPIO.HIGH)
GPIO.output(self.LEFT\_BEHIND\_2, GPIO.LOW)
GPIO.output(self.RIGHT\_BEHIND\_1, GPIO.HIGH)
GPIO.output(self.RIGHT\_BEHIND\_2, GPIO.LOW)
def \_\_backword(self):
self.reset()
GPIO.output(self.LEFT\_FRONT\_2, GPIO.HIGH)
GPIO.output(self.LEFT\_FRONT\_1, GPIO.LOW)
GPIO.output(self.RIGHT\_FRONT\_2, GPIO.HIGH)
GPIO.output(self.RIGHT\_FRONT\_1, GPIO.LOW)
GPIO.output(self.LEFT\_BEHIND\_2, GPIO.HIGH)
GPIO.output(self.LEFT\_BEHIND\_1, GPIO.LOW)
GPIO.output(self.RIGHT\_BEHIND\_2, GPIO.HIGH)
GPIO.output(self.RIGHT\_BEHIND\_1, GPIO.LOW)
def \_\_turnLeft(self):
'''
To turn left, the LEFT\_FRONT wheel will move backword
All other wheels move forword
'''
self.reset()
GPIO.output(self.LEFT\_FRONT\_2, GPIO.HIGH)
GPIO.output(self.LEFT\_FRONT\_1, GPIO.LOW)
GPIO.output(self.RIGHT\_FRONT\_1, GPIO.HIGH)
GPIO.output(self.RIGHT\_FRONT\_2, GPIO.LOW)
GPIO.output(self.LEFT\_BEHIND\_1, GPIO.HIGH)
GPIO.output(self.LEFT\_BEHIND\_2, GPIO.LOW)
GPIO.output(self.RIGHT\_BEHIND\_1, GPIO.HIGH)
GPIO.output(self.RIGHT\_BEHIND\_2, GPIO.LOW)
def \_\_turnRight(self):
'''
To turn right, the RIGHT\_FRONT wheel move backword
All other wheels move forword
'''
self.reset()
GPIO.output(self.LEFT\_FRONT\_1, GPIO.HIGH)
GPIO.output(self.LEFT\_FRONT\_2, GPIO.LOW)
GPIO.output(self.RIGHT\_FRONT\_2, GPIO.HIGH)
GPIO.output(self.RIGHT\_FRONT\_1, GPIO.LOW)
GPIO.output(self.LEFT\_BEHIND\_1, GPIO.HIGH)
GPIO.output(self.LEFT\_BEHIND\_2, GPIO.LOW)
GPIO.output(self.RIGHT\_BEHIND\_1, GPIO.HIGH)
GPIO.output(self.RIGHT\_BEHIND\_2, GPIO.LOW)
def \_\_backLeft(self):
'''
To go backword and turn left, the LEFT\_BEHIND wheel move forword
All other wheels move backword
'''
self.reset()
GPIO.output(self.LEFT\_FRONT\_2, GPIO.HIGH)
GPIO.output(self.LEFT\_FRONT\_1, GPIO.LOW)
GPIO.output(self.RIGHT\_FRONT\_2, GPIO.HIGH)
GPIO.output(self.RIGHT\_FRONT\_1, GPIO.LOW)
GPIO.output(self.LEFT\_BEHIND\_1, GPIO.HIGH)
GPIO.output(self.LEFT\_BEHIND\_2, GPIO.LOW)
GPIO.output(self.RIGHT\_BEHIND\_2, GPIO.HIGH)
GPIO.output(self.RIGHT\_BEHIND\_1, GPIO.LOW)
def \_\_backRight(self):
'''
To go backword and turn right, the RIGHT\_BEHIND wheel move forword
All other wheels move backword
'''
self.reset()
GPIO.output(self.LEFT\_FRONT\_2, GPIO.HIGH)
GPIO.output(self.LEFT\_FRONT\_1, GPIO.LOW)
GPIO.output(self.RIGHT\_FRONT\_2, GPIO.HIGH)
GPIO.output(self.RIGHT\_FRONT\_1, GPIO.LOW)
GPIO.output(self.LEFT\_BEHIND\_2, GPIO.HIGH)
GPIO.output(self.LEFT\_BEHIND\_1, GPIO.LOW)
GPIO.output(self.RIGHT\_BEHIND\_1, GPIO.HIGH)
GPIO.output(self.RIGHT\_BEHIND\_2, GPIO.LOW)
def \_\_stop(self):
self.reset()
def carMove(self, direction):
'''
Car move according to the input paramter - direction
'''
if direction == 'F':
self.\_\_forword()
elif direction == 'B':
self.\_\_backword()
elif direction == 'L':
self.\_\_turnLeft()
elif direction == 'R':
self.\_\_turnRight()
elif direction == 'BL':
self.\_\_backLeft()
elif direction == 'BR':
self.\_\_backRight()
elif direction == 'S':
self.\_\_stop()
else:
print("The input direction is wrong! You can just input: F, B, L, R, BL,BR or S")
if \_\_name\_\_ == "\_\_main\_\_":
raspCar = FourWheelDriveCar()
while(True):
direction = input("Please input direction: ")
