ROS机器人Diego 1#制作（三）base controller---ros_arduino_bridge

本文链接：https://blog.youkuaiyun.com/mwlwlm/article/details/52979723

本文详细介绍如何使用ros_arduino_bridge在ROS与Arduino间建立通信，包括安装配置、Arduino代码开发及ROS上位机开发等内容。

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ros_arduino_bridge封装了通过串口于底盘控制器Arduino的通信，并提供了一个标准的base controller，所以对arduino资源的占用非常小，arduino只是作为一个单纯的硬件控制器来使用，而所有的运算逻辑都放在上位机进行，通过串口指令的方式控制Arduino程序的运行。在Arduino UNO编译一个完整的ros_arduino_bridge后的资源占用情况如下图：
这里写图片描述
从上图可以看出占用资源非常上，用户还可以在Arduino UNO开发更多的应用，接更多的传感器。

1.ros_arduino_bridge的安装

a.下载
进入你的workspace目录下的src目录，catkin_ws是workspace

cd ~/catkin_ws/src
git clone https://github.com/hbrobotics/ros_arduino_bridge.git

b.编译，在workspace目录编译

cd <catkin_ws>
catkin_make

c.拷贝Arduino看库文件到，相应的Arduino IDE的libraries目录

$ cd SKETCHBOOK_PATH//Arduino IDE的库文件目录
$ \cp -rp  `rospack find ros_arduino_firmware`/src/libraries/ROSArduinoBridge -T ROSArduinoBridge

这时候可以把ROSArduinoBridge拷贝到其他windows， Mac电脑的Arduino IDE环境下使用，重启后既可以用
这里写图片描述

2.开发Arduino 代码

a.从Example中打开ROSArduinoBridge的示例代码，另存为自己喜欢的项目名称，我们只需要根据自己的需求修改示例代码即可
这里写图片描述

b.示例代码文件介绍

ROSArduinoBridge.ino 主程序
commands.h 串口命令的预定义
diff_controller.h PID控制代码
encoder_driver.h 编码器，这里只是针对了Arduino UNO，使用了中断接口D2,D3,和模拟接口A4，A5；所以电机编码器的输出接线需要按照此规则接线，另外要注意编码器要有两路输出
左侧电机的编码输出接D2,D3；右侧电机的编码输出接A4,A5
encoder_driver.ino 编码器的实现代码
motor_driver.h 马达驱动的接口定义，用不动的马达驱动板都要实现此文件定义的三个函数
motor_driver.ino马达驱动实现代码，根据预定义选择不同的驱动板库，在这里我使用了L298P，所以需要自己实现一个新的驱动库，后面会介绍
sensors.h传感器的实现文件
servos.h舵机的实现文件

c.为了满足我们控制的需要需要修改的是ROSArduinoBridge.ino文件，主要修改的点如下：

启用Base Controller

#define USE_BASE      // Enable the base controller code启用base controller
//#undef USE_BASE     // Disable the base controller code

马达控制板定义

/* Define the motor controller and encoder library you are using */
#ifdef USE_BASE
   /* The Pololu VNH5019 dual motor driver shield */
   //#define POLOLU_VNH5019

   /* The L298P dual motor driver shield，这里我们使用我们自己写的L298P库 */
   #define L298P
   

   /* The Pololu MC33926 dual motor driver shield */
   //#define POLOLU_MC33926

   /* The RoboGaia encoder shield */
   //#define ROBOGAIA
   
   /* Encoders directly attached to Arduino board，启用Arduino UNO的板载Encoder功能 */
   #define ARDUINO_ENC_COUNTER
#endif

定义电机PWM控制范围

/* Maximum PWM signal */
#define MAX_PWM        255//最大的PWM为255

d.motor_driver.ino的修改///主要是增加对L298P马达驱动板的支持

/***************************************************************
   Motor driver definitions
   
   Add a "#elif defined" block to this file to include support
   for a particular motor driver.  Then add the appropriate
   #define near the top of the main ROSArduinoBridge.ino file.
   
   *************************************************************/

#ifdef USE_BASE
   
#if defined POLOLU_VNH5019
  /* Include the Pololu library */
  #include "DualVNH5019MotorShield.h"

  /* Create the motor driver object */
  DualVNH5019MotorShield drive;
  
  /* Wrap the motor driver initialization */
  void initMotorController() {
    drive.init();
  }

  /* Wrap the drive motor set speed function */
  void setMotorSpeed(int i, int spd) {
    if (i == LEFT) drive.setM1Speed(spd);
    else drive.setM2Speed(spd);
  }

  // A convenience function for setting both motor speeds
  void setMotorSpeeds(int leftSpeed, int rightSpeed) {
    setMotorSpeed(LEFT, leftSpeed);
    setMotorSpeed(RIGHT, rightSpeed);
  }
#elif defined POLOLU_MC33926
  /* Include the Pololu library */
  #include "DualMC33926MotorShield.h"

  /* Create the motor driver object */
  DualMC33926MotorShield drive;
  
  /* Wrap the motor driver initialization */
  void initMotorController() {
    drive.init();
  }

  /* Wrap the drive motor set speed function */
  void setMotorSpeed(int i, int spd) {
    if (i == LEFT) drive.setM1Speed(spd);
    else drive.setM2Speed(spd);
  }

  // A convenience function for setting both motor speeds
  void setMotorSpeeds(int leftSpeed, int rightSpeed) {
    setMotorSpeed(LEFT, leftSpeed);
    setMotorSpeed(RIGHT, rightSpeed);
  }
#elif defined L298P////////增加对L298P的支持
   #include "DualL298PMotorShield.h"

  /* Create the motor driver object */
  DualL298PMotorShield drive;
  /* Wrap the motor driver initialization */
  void initMotorController() {
    drive.init();
  }

  /* Wrap the drive motor set speed function */
  void setMotorSpeed(int i, int spd) {
    if (i == LEFT) drive.setM1Speed(spd);
    else drive.setM2Speed(spd);
  }

  // A convenience function for setting both motor speeds
  void setMotorSpeeds(int leftSpeed, int rightSpeed) {
    setMotorSpeed(LEFT, leftSpeed);
    setMotorSpeed(RIGHT, rightSpeed);
  }
  
#else
  #error A motor driver must be selected!
#endif

#endif

e.L298P的驱动库，把.h和.cpp文件放在同一个目录下，拷贝到Arduino IDE的库文件目录下就可以。
DualL298PMotorShield.h代码

#ifndef DualL298PMotorShield_h
#define DualL298PMotorShield_h

#include <Arduino.h>

class DualL298PMotorShield
{
  public:  
    // CONSTRUCTORS
    DualL298PMotorShield(); // Default pin selection.
    DualL298PMotorShield(unsigned char M1DIR, unsigned char M1PWM,
                           unsigned char M2DIR, unsigned char M2PWM); // User-defined 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 setSpeeds(int m1Speed, int m2Speed); // Set speed for both M1 and M2.
    
  private:
    static const unsigned char _M1DIR = 4;
    static const unsigned char _M2DIR = 7;
    static const unsigned char _M1PWM = 5;
    static const unsigned char _M2PWM = 6;
};

#endif

DualL298PMotorShield.cpp代码

#include "DualL298PMotorShield.h"

// Constructors ////////////////////////////////////////////////////////////////

DualL298PMotorShield::DualL298PMotorShield()
{
  //Pin map

}


// Public Methods //////////////////////////////////////////////////////////////
void DualL298PMotorShield::init()
{
// Define pinMode for the pins and set the frequency for timer1.

  pinMode(_M1DIR,OUTPUT);
  pinMode(_M1PWM,OUTPUT);
  pinMode(_M2DIR,OUTPUT);
  pinMode(_M2PWM,OUTPUT);
  
}
// Set speed for motor 1, speed is a number betwenn -400 and 400
void DualL298PMotorShield::setM1Speed(int speed)
{
  unsigned char reverse = 0;
  
  if (speed < 0)
  {
    speed = -speed;  // Make speed a positive quantity
    reverse = 1;  // Preserve the direction
  }
  if (speed > 255)  // Max PWM dutycycle
    speed = 255;
  if (reverse)
  {
    digitalWrite(_M1DIR,LOW);
    analogWrite(_M1PWM, speed);
  }
  else
  {
    digitalWrite(_M1DIR,HIGH);
    analogWrite(_M1PWM, speed);
  }    
}

// Set speed for motor 2, speed is a number betwenn -400 and 400
void DualL298PMotorShield::setM2Speed(int speed)
{
  unsigned char reverse = 0;
  
  if (speed < 0)
  {
    speed = -speed;  // Make speed a positive quantity
    reverse = 1;  // Preserve the direction
  }
  if (speed > 255)  // Max PWM dutycycle
    speed = 255;
  if (reverse)
  {
    digitalWrite(_M2DIR,LOW);
    analogWrite(_M2PWM, speed);
  }
  else
  {
    digitalWrite(_M2DIR,HIGH);
    analogWrite(_M2PWM, speed);
  }
}

// Set speed for motor 1 and 2
void DualL298PMotorShield::setSpeeds(int m1Speed, int m2Speed)
{
  setM1Speed(m1Speed);
  setM2Speed(m2Speed);
}

修改完成后变可以编译upload到Arduino UNO上了。

3.ROS上位机开发

a.配置你的机器人参数
进入配置文件目录

$ roscd ros_arduino_python/config

拷贝一份新的配置文件

$ cp arduino_params.yaml my_arduino_params.yaml

用nano打开编辑

sudo nano my_arduino_params.yaml

修改后的my_arduino_params.yaml如下图，主要修改就是启用base Controller，修改PID参数，修改机器人的参数：

# For a direct USB cable connection, the port name is typically
# /dev/ttyACM# where is # is a number such as 0, 1, 2, etc
# For a wireless connection like XBee, the port is typically
# /dev/ttyUSB# where # is a number such as 0, 1, 2, etc.

port: /dev/ttyACM0
baud: 57600
timeout: 0.1

rate: 50
sensorstate_rate: 10

use_base_controller: True
base_controller_rate: 10

# For a robot that uses base_footprint, change base_frame to base_footprint
base_frame: base_link

# === Robot drivetrain parameters
wheel_diameter: 0.02900 #轮胎直径
wheel_track: 0.18 #两个轮胎间距
encoder_resolution: 2 # 码盘孔数
gear_reduction: 75.0 #转速比
motors_reversed: True

# === PID parameters
Kp: 10
Kd: 12
Ki: 0
Ko: 50
accel_limit: 1.0

# === Sensor definitions.  Examples only - edit for your robot.
#     Sensor type can be one of the follow (case sensitive!):
#	  * Ping
#	  * GP2D12
#	  * Analog
#	  * Digital
#	  * PololuMotorCurrent
#	  * PhidgetsVoltage
#	  * PhidgetsCurrent (20 Amp, DC)



sensors: {
  #motor_current_left:   {pin: 4, type: PololuMotorCurrent, rate: 5},
  #motor_current_right:  {pin: 7, type: PololuMotorCurrent, rate: 5},
  #ir_front_center:      {pin: 2, type: GP2D12, rate: 10},
  #sonar_front_center:   {pin: 5, type: Ping, rate: 10},
  arduino_led:          {pin: 13, type: Digital, rate: 5, direction: output}
}

修改完成后，既可以运行了
b.运行测试
启动roscore

roscore

增加路径到bash

. ~/catkin_ws/devel/setup.bash

启动节点

roslaunch ros_arduino_python arduino.launch

启动后的截图
这里写图片描述

这时候我们可以发布Twist消息来控制机器人的运行，如：

rostopic pub /cmd_vel geometry_msgs/Twist -r 1 -- '[2.0, 0.0, 0.0]' '[0.0, 0.0, 1.8]'

运行此命令，机器人会原地打转，用如下命令查看odom的信息，此信息会不断的变化

rostopic echo /odom
```![这里写图片描述](https://imgconvert.csdnimg.cn/aHR0cDovL2ltZy5ibG9nLmNzZG4ubmV0LzIwMTYxMDMxMDkyODQ4ODQ2?x-oss-process=image/format,png)

至此机器人已经可以按照Twist消息进行控制，发布功move base使用的odom信息，不过做到这里，为了控制精度，我们还需要标定机器人，即标定机器人按照机器人给定的线速度，和角速度行进，下篇博文，我们将讲述如何标定。