查看“树莓派智能车AlphaBot教程2：直流电机控制”的源代码



一台小车首先要有电机轮子，通过控制电机转动，小车实现不同方向行走。


电机可以是直流电机或者步进电机。
步进电机是以步阶方式分段移动，也就是每次只能控制转动一小段。所以步进电机的控制精度会很高，可以精确的控制转动距离，但是转速会比较慢。在控制精度要求很高的情况会用，例如机械手臂等。
而直流电机则相反，转速快，但是控制精度相对差。直流电机是通过电压控制，通电后电机就可以转，电压越大转速越快，电流方向决定电机转动方向。智能车多少采用直流电机控制。


直流电机通常采用H桥控制。H桥式
电机驱动
电路包括4个
三极管
和一个电机。要使电机运转，必须导通对角线上的一对三极管。电流可能会从左至右或从右至左流过电机，从而控制电机的转向。


[[File:102638lxnllxsbccvxvv9l.jpg]]

当Q1管和Q4管导通时，电流就从电源正极经Q1从左至右穿过电机，然后再经Q4回到电源负极。电流将驱动电机顺时针转动。


[[File:135119s1h4dwtrvtwtd1fo.jpg]]

当Q2和Q3导通时，电流将从右至左流过电机。此时电流将驱动电机逆针转动。




[[File:135119dvdmr866jnsqy5dy.jpg]]



实际使用的时候，用分立元件制作H桥是很麻烦的，很多时候采用H桥集成电路，接上电源、电机和控制信号就可以使用了，比如常用的L293D、L298N、TB6612FNG等。






[[File:135120v6dldem5d5m1mm9k.png]]





[[File:135120lxtzah0nfyooauhh.png]]





上面两个图分别对应AlphaBot(L298P),AlphaBot2(TB6612FNG)的驱动电路图。这两个需要采用不同的芯片，但是控制方式是完全一样的。下面以TB6612FNG为例讲解。
这两个芯片都是对应A B两组H桥，分别控制两个电机。A组控制左轮，B组控制右轮。
每个电机分别由三个管脚控制，AIN1 AIN2两个管脚控制方向，PWMA通过PWM脉冲控制电机转动。
AIN1,AIN2电平一样时，电机不转，电平不一样时电机转动，转动方向和AIN1，AIN2的电平有关。
这里假设AIN1为低电平，AIN2为高电平时，电机正转，轮子向前走。BIN1为低电平，BIN2为高电平时，电机正转，轮子向前走。
控制原理
<table border="1" cellpadding="0" cellspacing="0" style="font-size: inherit; border-collapse: collapse; margin: 3px 0px; overflow: visible; table-layout: fixed; border-spacing: 0px; border: 1px solid rgb(204, 204, 204); width: 603px;"><tbody><tr arial="" border:="" break-all="" break-word="" color:="" font-size:="" gb="" heiti="" helvetica="" line-height:="" middle="" normal="" padding:="" pingfang="" rgb="" sans="" sans-serif="" sc="" simsun="" solid="" style="font-family: -apple-system, BlinkMacSystemFont, " tahoma="" vertical-align:="" word-break:="" word-wrap:="" yahei=""><td style="word-break: break-all; word-wrap: break-word; border: 1px solid rgb(153, 153, 153); padding: 5px 10px; min-height: 25px; min-width: 25px; height: 23px; background-color: rgb(242, 242, 242); width: 70px; font-weight: bold; font-family: 微软雅黑; font-size: 16px; text-align: center; vertical-align: middle; color: rgb(0, 0, 0);">AIN1</td><td style="word-break: break-all; word-wrap: break-word; border: 1px solid rgb(153, 153, 153); padding: 5px 10px; min-height: 25px; min-width: 25px; height: 23px; background-color: rgb(242, 242, 242); width: 70px; font-weight: bold; font-family: 微软雅黑; font-size: 16px; text-align: center; vertical-align: middle; color: rgb(0, 0, 0);">AIN2</td><td style="word-break: break-all; word-wrap: break-word; border: 1px solid rgb(153, 153, 153); padding: 5px 10px; min-height: 25px; min-width: 25px; height: 23px; background-color: rgb(242, 242, 242); width: 70px; font-weight: bold; font-family: 微软雅黑; font-size: 16px; text-align: center; vertical-align: middle; color: rgb(0, 0, 0);">BIN1</td><td style="word-break: break-all; word-wrap: break-word; border: 1px solid rgb(153, 153, 153); padding: 5px 10px; min-height: 25px; min-width: 25px; height: 23px; background-color: rgb(242, 242, 242); width: 70px; font-weight: bold; font-family: 微软雅黑; font-size: 16px; text-align: center; vertical-align: middle; color: rgb(0, 0, 0);">BIN2</td><td style="word-break: break-all; word-wrap: break-word; border: 1px solid rgb(153, 153, 153); padding: 5px 10px; min-height: 25px; min-width: 25px; height: 23px; background-color: rgb(242, 242, 242); width: 323px; font-weight: bold; font-family: 微软雅黑; font-size: 16px; text-align: center; vertical-align: middle; color: rgb(0, 0, 0);">描述</td></tr><tr arial="" border:="" break-all="" break-word="" color:="" font-size:="" gb="" heiti="" helvetica="" line-height:="" middle="" normal="" padding:="" pingfang="" rgb="" sans="" sans-serif="" sc="" simsun="" solid="" style="font-family: -apple-system, BlinkMacSystemFont, " tahoma="" vertical-align:="" word-break:="" word-wrap:="" yahei=""><td style="word-break: break-all; word-wrap: break-word; border: 1px solid rgb(153, 153, 153); padding: 5px 10px; min-height: 25px; min-width: 25px; height: 23px; background-color: rgb(249, 249, 249); width: 70px; font-family: 微软雅黑; font-size: 16px; text-align: center; vertical-align: middle; color: rgb(0, 0, 0);">0</td><td style="word-break: break-all; word-wrap: break-word; border: 1px solid rgb(153, 153, 153); padding: 5px 10px; min-height: 25px; min-width: 25px; height: 23px; background-color: rgb(249, 249, 249); width: 70px; font-family: 微软雅黑; font-size: 16px; text-align: center; vertical-align: middle; color: rgb(0, 0, 0);">1</td><td style="word-break: break-all; word-wrap: break-word; border: 1px solid rgb(153, 153, 153); padding: 5px 10px; min-height: 25px; min-width: 25px; height: 23px; background-color: rgb(249, 249, 249); width: 70px; font-family: 微软雅黑; font-size: 16px; text-align: center; vertical-align: middle; color: rgb(0, 0, 0);">0</td><td style="word-break: break-all; word-wrap: break-word; border: 1px solid rgb(153, 153, 153); padding: 5px 10px; min-height: 25px; min-width: 25px; height: 23px; background-color: rgb(249, 249, 249); width: 70px; font-family: 微软雅黑; font-size: 16px; text-align: center; vertical-align: middle; color: rgb(0, 0, 0);">1</td><td style="word-break: break-all; word-wrap: break-word; border: 1px solid rgb(153, 153, 153); padding: 5px 10px; min-height: 25px; min-width: 25px; height: 23px; background-color: rgb(249, 249, 249); width: 323px; font-family: 微软雅黑; font-size: 16px; text-align: center; vertical-align: middle; color: rgb(0, 0, 0);">左右电机正转，小车前进</td></tr><tr arial="" border:="" break-all="" break-word="" color:="" font-size:="" gb="" heiti="" helvetica="" line-height:="" middle="" normal="" padding:="" pingfang="" rgb="" sans="" sans-serif="" sc="" simsun="" solid="" style="font-family: -apple-system, BlinkMacSystemFont, " tahoma="" vertical-align:="" word-break:="" word-wrap:="" yahei=""><td style="word-break: break-all; word-wrap: break-word; border: 1px solid rgb(153, 153, 153); padding: 5px 10px; min-height: 25px; min-width: 25px; height: 23px; background-color: rgb(249, 249, 249); width: 70px; font-family: 微软雅黑; font-size: 16px; text-align: center; vertical-align: middle; color: rgb(0, 0, 0);">1</td><td style="word-break: break-all; word-wrap: break-word; border: 1px solid rgb(153, 153, 153); padding: 5px 10px; min-height: 25px; min-width: 25px; height: 23px; background-color: rgb(249, 249, 249); width: 70px; font-family: 微软雅黑; font-size: 16px; text-align: center; vertical-align: middle; color: rgb(0, 0, 0);">0</td><td style="word-break: break-all; word-wrap: break-word; border: 1px solid rgb(153, 153, 153); padding: 5px 10px; min-height: 25px; min-width: 25px; height: 23px; background-color: rgb(249, 249, 249); width: 70px; font-family: 微软雅黑; font-size: 16px; text-align: center; vertical-align: middle; color: rgb(0, 0, 0);">1</td><td style="word-break: break-all; word-wrap: break-word; border: 1px solid rgb(153, 153, 153); padding: 5px 10px; min-height: 25px; min-width: 25px; height: 23px; background-color: rgb(249, 249, 249); width: 70px; font-family: 微软雅黑; font-size: 16px; text-align: center; vertical-align: middle; color: rgb(0, 0, 0);">0</td><td style="word-break: break-all; word-wrap: break-word; border: 1px solid rgb(153, 153, 153); padding: 5px 10px; min-height: 25px; min-width: 25px; height: 23px; background-color: rgb(249, 249, 249); width: 323px; font-family: 微软雅黑; font-size: 16px; text-align: center; vertical-align: middle; color: rgb(0, 0, 0);">左右电机反转，小车后退</td></tr><tr arial="" border:="" break-all="" break-word="" color:="" font-size:="" gb="" heiti="" helvetica="" line-height:="" middle="" normal="" padding:="" pingfang="" rgb="" sans="" sans-serif="" sc="" simsun="" solid="" style="font-family: -apple-system, BlinkMacSystemFont, " tahoma="" vertical-align:="" word-break:="" word-wrap:="" yahei=""><td style="word-break: break-all; word-wrap: break-word; border: 1px solid rgb(153, 153, 153); padding: 5px 10px; min-height: 25px; min-width: 25px; height: 23px; background-color: rgb(249, 249, 249); width: 70px; font-family: 微软雅黑; font-size: 16px; text-align: center; vertical-align: middle; color: rgb(0, 0, 0);">0</td><td style="word-break: break-all; word-wrap: break-word; border: 1px solid rgb(153, 153, 153); padding: 5px 10px; min-height: 25px; min-width: 25px; height: 23px; background-color: rgb(249, 249, 249); width: 70px; font-family: 微软雅黑; font-size: 16px; text-align: center; vertical-align: middle; color: rgb(0, 0, 0);">1</td><td style="word-break: break-all; word-wrap: break-word; border: 1px solid rgb(153, 153, 153); padding: 5px 10px; min-height: 25px; min-width: 25px; height: 23px; background-color: rgb(249, 249, 249); width: 70px; font-family: 微软雅黑; font-size: 16px; text-align: center; vertical-align: middle; color: rgb(0, 0, 0);">1</td><td style="word-break: break-all; word-wrap: break-word; border: 1px solid rgb(153, 153, 153); padding: 5px 10px; min-height: 25px; min-width: 25px; height: 23px; background-color: rgb(249, 249, 249); width: 70px; font-family: 微软雅黑; font-size: 16px; text-align: center; vertical-align: middle; color: rgb(0, 0, 0);">0</td><td style="word-break: break-all; word-wrap: break-word; border: 1px solid rgb(153, 153, 153); padding: 5px 10px; min-height: 25px; min-width: 25px; height: 23px; background-color: rgb(249, 249, 249); width: 323px; font-family: 微软雅黑; font-size: 16px; text-align: center; vertical-align: middle; color: rgb(0, 0, 0);">右电机反转，左电机正转，小车右转</td></tr><tr arial="" border:="" break-all="" break-word="" color:="" font-size:="" gb="" heiti="" helvetica="" line-height:="" middle="" normal="" padding:="" pingfang="" rgb="" sans="" sans-serif="" sc="" simsun="" solid="" style="font-family: -apple-system, BlinkMacSystemFont, " tahoma="" vertical-align:="" word-break:="" word-wrap:="" yahei=""><td style="word-break: break-all; word-wrap: break-word; border: 1px solid rgb(153, 153, 153); padding: 5px 10px; min-height: 25px; min-width: 25px; height: 23px; background-color: rgb(249, 249, 249); width: 70px; font-family: 微软雅黑; font-size: 16px; text-align: center; vertical-align: middle; color: rgb(0, 0, 0);">1</td><td style="word-break: break-all; word-wrap: break-word; border: 1px solid rgb(153, 153, 153); padding: 5px 10px; min-height: 25px; min-width: 25px; height: 23px; background-color: rgb(249, 249, 249); width: 70px; font-family: 微软雅黑; font-size: 16px; text-align: center; vertical-align: middle; color: rgb(0, 0, 0);">0</td><td style="word-break: break-all; word-wrap: break-word; border: 1px solid rgb(153, 153, 153); padding: 5px 10px; min-height: 25px; min-width: 25px; height: 23px; background-color: rgb(249, 249, 249); width: 70px; font-family: 微软雅黑; font-size: 16px; text-align: center; vertical-align: middle; color: rgb(0, 0, 0);">0</td><td style="word-break: break-all; word-wrap: break-word; border: 1px solid rgb(153, 153, 153); padding: 5px 10px; min-height: 25px; min-width: 25px; height: 23px; background-color: rgb(249, 249, 249); width: 70px; font-family: 微软雅黑; font-size: 16px; text-align: center; vertical-align: middle; color: rgb(0, 0, 0);">1</td><td style="word-break: break-all; word-wrap: break-word; border: 1px solid rgb(153, 153, 153); padding: 5px 10px; min-height: 25px; min-width: 25px; height: 23px; background-color: rgb(249, 249, 249); width: 323px; font-family: 微软雅黑; font-size: 16px; text-align: center; vertical-align: middle; color: rgb(0, 0, 0);">左电机反转，右电机正转，小车左转</td></tr><tr arial="" border:="" break-all="" break-word="" color:="" font-size:="" gb="" heiti="" helvetica="" line-height:="" middle="" normal="" padding:="" pingfang="" rgb="" sans="" sans-serif="" sc="" simsun="" solid="" style="font-family: -apple-system, BlinkMacSystemFont, " tahoma="" vertical-align:="" word-break:="" word-wrap:="" yahei=""><td style="word-break: break-all; word-wrap: break-word; border: 1px solid rgb(153, 153, 153); padding: 5px 10px; min-height: 25px; min-width: 25px; height: 23px; background-color: rgb(249, 249, 249); width: 70px; font-family: 微软雅黑; font-size: 16px; text-align: center; vertical-align: middle; color: rgb(0, 0, 0);">0</td><td style="word-break: break-all; word-wrap: break-word; border: 1px solid rgb(153, 153, 153); padding: 5px 10px; min-height: 25px; min-width: 25px; height: 23px; background-color: rgb(249, 249, 249); width: 70px; font-family: 微软雅黑; font-size: 16px; text-align: center; vertical-align: middle; color: rgb(0, 0, 0);">0</td><td style="word-break: break-all; word-wrap: break-word; border: 1px solid rgb(153, 153, 153); padding: 5px 10px; min-height: 25px; min-width: 25px; height: 23px; background-color: rgb(249, 249, 249); width: 70px; font-family: 微软雅黑; font-size: 16px; text-align: center; vertical-align: middle; color: rgb(0, 0, 0);">0</td><td style="word-break: break-all; word-wrap: break-word; border: 1px solid rgb(153, 153, 153); padding: 5px 10px; min-height: 25px; min-width: 25px; height: 23px; background-color: rgb(249, 249, 249); width: 70px; font-family: 微软雅黑; font-size: 16px; text-align: center; vertical-align: middle; color: rgb(0, 0, 0);">0</td><td style="word-break: break-all; word-wrap: break-word; border: 1px solid rgb(153, 153, 153); padding: 5px 10px; min-height: 25px; min-width: 25px; height: 23px; background-color: rgb(249, 249, 249); width: 323px; font-family: 微软雅黑; font-size: 16px; text-align: center; vertical-align: middle; color: rgb(0, 0, 0);">左右电机停止，小车停止</td></tr></tbody></table>


下面对应arduino的程序。

<syntaxhighlight lang="python">
void forward()
{
analogWrite(PWMA,Speed);
analogWrite(PWMB,Speed);
digitalWrite(AIN1,LOW);
digitalWrite(AIN2,HIGH);
digitalWrite(BIN1,LOW);
digitalWrite(BIN2,HIGH);
}
void backward()
{
analogWrite(PWMA,Speed);
analogWrite(PWMB,Speed);
digitalWrite(AIN1,HIGH);
digitalWrite(AIN2,LOW);
digitalWrite(BIN1,HIGH);
digitalWrite(BIN2,LOW);
}
void right()
{
analogWrite(PWMA,50);
analogWrite(PWMB,50);
digitalWrite(AIN1,LOW);
digitalWrite(AIN2,HIGH);
digitalWrite(BIN1,HIGH);
digitalWrite(BIN2,LOW);
}
void left()
{
analogWrite(PWMA,50);
analogWrite(PWMB,50);
digitalWrite(AIN1,HIGH);
digitalWrite(AIN2,LOW);
digitalWrite(BIN1,LOW);
digitalWrite(BIN2,HIGH);
}
void stop()
{
analogWrite(PWMA,0);
analogWrite(PWMB,0);
digitalWrite(AIN1,LOW);
digitalWrite(AIN2,LOW);
digitalWrite(BIN1,LOW);
digitalWrite(BIN2,LOW);
}</syntaxhighlight> 



如果程序转动方向和实际转动方向不一致，可能是电机接线方向和我们的假设不一样。可以更改电机接线或者修改电机对应的引脚。