Lesson 24:Diego 1# 4WD —No.2:motor control

针对马达控制我们主要需要修改两部分:

  • 驱动部分,使其可以支持同时控制4个马达
  • PID调速部分,试验表明,虽然是一样的型号的马达,但是给相同的PWM值,马达的转速也不一样,所以我们需要分别对4个马达进行PID调速

1.马达驱动

1.1. DualL298PMotorShield4WD.h文件的修改
增加了4个马达对应的PWM和方向控制的Pin引脚定义,和4个马达速度的设置函数

#ifndef DualL298PMotorShield4WD_h
#define DualL298PMotorShield4WD_h

#include 

class DualL298PMotorShield4WD
{
  public:  
    // CONSTRUCTORS
    DualL298PMotorShield4WD(); // Default pin selection.
    
    // PUBLIC METHODS
    void init(); // Initialize TIMER 1, set the PWM to 20kHZ. 
    void setM1Speed(int speed); // Set speed for M1.
    void setM2Speed(int speed); // Set speed for M2.
    void setM3Speed(int speed); // Set speed for M3.
    void setM4Speed(int speed); // Set speed for M4.
    void setSpeeds(int m1Speed, int m2Speed, int m3Speed, int m4Speed); // Set speed for both M1 and M2.
    
  private:
  
    // left motor
    static const unsigned char _M1DIR = 12;
    static const unsigned char _M2DIR = 7;
    static const unsigned char _M1PWM = 10;
    static const unsigned char _M2PWM = 6;
    
    // right motor
    static const unsigned char _M4DIR = 8;
    static const unsigned char _M3DIR = 13;
    static const unsigned char _M4PWM = 9;
    static const unsigned char _M3PWM = 11;
    
};

#endif

1.2. DualL298PMotorShield4WD.cpp文件的修改

主要是针对4个马达速度设置函数的实现,逻辑都是一样的,这里只截取一个马达的代码,代码的逻辑请看代码注释

// Set speed for motor 4, speed is a number betwenn -400 and 400
void DualL298PMotorShield4WD::setM4Speed(int speed)
{
  unsigned char reverse = 0;
  
  if (speed < 0) //速度是否小于0 { speed = -speed; // 如果小于0,则是反转 reverse = 1; // 反转标志变量设置为1 } if (speed > 255)  // 限定最大速度为255
    speed = 255;
  if (reverse)  //反转状态下
  {
    digitalWrite(_M4DIR,LOW);//设定马达转向的pin位低电平
    analogWrite(_M4PWM, speed);
  }
  else //正向转动状态下
  {
    digitalWrite(_M4DIR,HIGH);设定马达转向的pin位高电平
    analogWrite(_M4PWM, speed);
  }
}

在setSpeeds函数中分别调用4个马达的速度设置函数。

// Set speed for motor 1, 2, 3, 4
void DualL298PMotorShield4WD::setSpeeds(int m1Speed, int m2Speed, int m3Speed, int m4Speed)
{
  setM1Speed(m1Speed);
  setM2Speed(m2Speed);
  setM3Speed(m3Speed);
  setM4Speed(m4Speed);  
}

DualL298PMotorShield4WD.h和DualL298PMotorShield4WD.cpp修改完成后,在arduino 的library目录下新建一个名为dual-L298P-motor-shield-master-4wd的目录,将两个文件放到此文件夹下

现在我们打开android ide的library就可以看到我们刚才添加的库

1.1.3 motor_driver.h的修改

增加4驱马达控制的函数setMotorSpeeds,参数为4个马达的速度

void initMotorController();
void setMotorSpeed(int i, int spd);
#ifdef L298P
void setMotorSpeeds(int leftSpeed, int rightSpeed);
#endif
#ifdef L298P_4WD
void setMotorSpeeds(int leftSpeed_1, int leftSpeed_2, int rightSpeed_1, int rightSpeed_2);
#endif

1.1.4 motor_driver.ino的修改

#ifdef L298P_4WD
// A convenience function for setting both motor speeds
void setMotorSpeeds(int leftSpeed_1, int leftSpeed_2, int rightSpeed_1, int rightSpeed_2){
  setMotorSpeed(1, leftSpeed_1);
  setMotorSpeed(3, rightSpeed_1);
  setMotorSpeed(2, leftSpeed_2);
  setMotorSpeed(4, rightSpeed_2);
}
#endif
#else
#error A motor driver must be selected!
#endif

2.PID控制

PID控制都在diff_controller.h文件中定义修改

新增两个在4驱模式下的PID控制变量

#ifdef L298P_4WD
SetPointInfo leftPID_h, rightPID_h;
#endif

新增两个在4驱模式下的PID控制参数

#ifdef L298P_4WD

int left_h_Kp=Kp;
int left_h_Kd=Kd;
int left_h_Ki=Ki;
int left_h_Ko=Ko;

int right_h_Kp=Kp;
int right_h_Kd=Kd;
int right_h_Ki=Ki;
int right_h_Ko=Ko;

#endif

新增两个在4驱模式下的PID控制函数

#ifdef L298P_4WD
/* PID routine to compute the next motor commands */
void dorightPID_h(SetPointInfo * p) {
  long Perror;
  long output;
  int input;

  //Perror = p->TargetTicksPerFrame - (p->Encoder - p->PrevEnc);
  input =  p->Encoder-p->PrevEnc ;
  Perror = p->TargetTicksPerFrame - input;

  /*
  * Avoid derivative kick and allow tuning changes,
  * see http://brettbeauregard.com/blog/2011/04/improving-the-beginner%E2%80%99s-pid-derivative-kick/
  * see http://brettbeauregard.com/blog/2011/04/improving-the-beginner%E2%80%99s-pid-tuning-changes/
  */
  //output = (Kp * Perror + Kd * (Perror - p->PrevErr) + Ki * p->Ierror) / Ko;
  // p->PrevErr = Perror;
  output = (right_h_Kp * Perror - right_h_Kd * (input - p->PrevInput) + p->ITerm) / right_h_Ko;
  p->PrevEnc = p->Encoder;

  output += p->output;
  // Accumulate Integral error *or* Limit output.
  // Stop accumulating when output saturates
  if (output >= MAX_PWM)
    output = MAX_PWM;
  else if (output <= -MAX_PWM) output = -MAX_PWM; else /* * allow turning changes, see http://brettbeauregard.com/blog/2011/04/improving-the-beginner%E2%80%99s-pid-tuning-changes/ */ p->ITerm += left_h_Ki * Perror;

  p->output = output;
  p->PrevInput = input;
//  Serial.println("right output:");
//  Serial.println(p->output);
}
#endif
...
#ifdef L298P_4WD

/* PID routine to compute the next motor commands */
void doleftPID_h(SetPointInfo * p) {
  long Perror;
  long output;
  int input;

  //Perror = p->TargetTicksPerFrame - (p->Encoder - p->PrevEnc);
  input = p->Encoder-p->PrevEnc ;
  Perror = p->TargetTicksPerFrame - input;

  /*
  * Avoid derivative kick and allow tuning changes,
  * see http://brettbeauregard.com/blog/2011/04/improving-the-beginner%E2%80%99s-pid-derivative-kick/
  * see http://brettbeauregard.com/blog/2011/04/improving-the-beginner%E2%80%99s-pid-tuning-changes/
  */
  //output = (Kp * Perror + Kd * (Perror - p->PrevErr) + Ki * p->Ierror) / Ko;
  // p->PrevErr = Perror;
  output = (left_h_Kp * Perror - left_h_Kd * (input - p->PrevInput) + p->ITerm) / left_h_Ko;
  p->PrevEnc = p->Encoder;

  output += p->output;
  // Accumulate Integral error *or* Limit output.
  // Stop accumulating when output saturates
  if (output >= MAX_PWM)
    output = MAX_PWM;
  else if (output <= -MAX_PWM) output = -MAX_PWM; else /* * allow turning changes, see http://brettbeauregard.com/blog/2011/04/improving-the-beginner%E2%80%99s-pid-tuning-changes/ */ p->ITerm += left_h_Ki * Perror;

  p->output = output;
  p->PrevInput = input;
//  Serial.println("left output:");
//  Serial.println(p->output);
}
#endif

修改readPIDIn函数,增加在4驱模式下,pidin的读取

long readPidIn(int i) {
  long pidin=0;
  if (i == LEFT){
    pidin = leftPID.PrevInput;
  }else if (i == RIGHT){
    pidin = rightPID.PrevInput;
  }
#ifdef L298P_4WD
  else if (i== RIGHT_H){
    pidin = rightPID_h.PrevInput;
  }else{
    pidin = leftPID_h.PrevInput;
  }
#endif  
  return pidin;
}

修改readPIDOut函数,增加在4驱模式下,pidOut的读取

long readPidOut(int i) {
  long pidout=0;
  if (i == LEFT){
    pidout = leftPID.output;
  }else if (i == RIGHT){
    pidout = rightPID.output;
  }
#ifdef L298P_4WD
  else if (i == RIGHT_H){
    pidout = rightPID_h.output;
  }else{
    pidout = leftPID_h.output;
  }
#endif   
  return pidout;
}

修改updatePID函数,增加在4驱模式下马达PID控制的调用

void updatePID() {
  /* Read the encoders */
  leftPID.Encoder =readEncoder(LEFT);
  rightPID.Encoder =readEncoder(RIGHT);
#ifdef L298P_4WD 
  leftPID_h.Encoder =readEncoder(LEFT_H);
  rightPID_h.Encoder =readEncoder(RIGHT_H);
#endif
  
  /* If we're not moving there is nothing more to do */
  if (!moving){
    /*
    * Reset PIDs once, to prevent startup spikes,
    * see http://brettbeauregard.com/blog/2011/04/improving-the-beginner%E2%80%99s-pid-initialization/
    * PrevInput is considered a good proxy to detect
    * whether reset has already happened
    */
#ifdef L298P    
    if (leftPID.PrevInput != 0 || rightPID.PrevInput != 0) resetPID();
#endif
#ifdef L298P_4WD
    if (leftPID.PrevInput != 0 || rightPID.PrevInput != 0 || leftPID_h.PrevInput != 0 || rightPID_h.PrevInput != 0) resetPID();
#endif    
    return;
  }

  /* Compute PID update for each motor */
  dorightPID(&rightPID);
  doleftPID(&leftPID);
#ifdef L298P_4WD
  dorightPID_h(&rightPID_h);
  doleftPID_h(&leftPID_h);
#endif  

  /* Set the motor speeds accordingly */
#ifdef L298P   
  setMotorSpeeds(leftPID.output, rightPID.output);
#endif

#ifdef L298P_4WD
  setMotorSpeeds(leftPID.output,leftPID_h.output, rightPID.output,rightPID_h.output);
#endif

}

至此4个马达已经可以独立驱动,独立的PID调速了,在下一篇教程中,会介绍如和上位机互动起来,让4驱底盘跑起来。

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