外贸推广网站建设,Wordpress 分表分库,c2g的代表性电商平台,逻辑图在线制作网站重要参考#xff1a;
课程链接:https://www.bilibili.com/video/BV1Ci4y1L7ZZ
讲义链接:Introduction Autolabor-ROS机器人入门课程《ROS理论与实践》零基础教程 8.4.5 底盘实现_04Arduino端PID控制
上一节最后测试时#xff0c;电机可能会出现抖动、顿挫的现象#xff…重要参考
课程链接:https://www.bilibili.com/video/BV1Ci4y1L7ZZ
讲义链接:Introduction · Autolabor-ROS机器人入门课程《ROS理论与实践》零基础教程 8.4.5 底盘实现_04Arduino端PID控制
上一节最后测试时电机可能会出现抖动、顿挫的现象显而易见的这是由于PID参数设置不合理导致的本节将介绍ros_arduino_bridge中的PID调试大致流程如下
了解ros_arduino_bridge中PID调试的流程实现PID调试。
1.ros_arduino_bridge中PID调试源码分析
基本思想
先定义调试频率(周期)并预先设置下一次的结束时刻当当前时刻大于预设的结束时刻时即进行PID调试且重置下一次调试结束时刻PID代码在diff_controller中实现PID的目标值是命令输入的转速当前转速则是通过读取当前编码器计数再减去上一次调试结束时记录的编码器计数获取最后输出 PWM
ROSArduinoBridge.ino 中和PID控制相关的变量
#ifdef USE_BASE/* Motor driver function definitions */#include motor_driver.h/* Encoder driver function definitions */#include encoder_driver.h/* PID parameters and functions */#include diff_controller.h/* Run the PID loop at 30 times per second */#define PID_RATE 30 // Hz PID调试频率/* Convert the rate into an interval */const int PID_INTERVAL 1000 / PID_RATE; // PID调试周期/* Track the next time we make a PID calculation */unsigned long nextPID PID_INTERVAL; //PID调试的结束时刻标记/* Stop the robot if it hasnt received a movement commandin this number of milliseconds */#define AUTO_STOP_INTERVAL 5000long lastMotorCommand AUTO_STOP_INTERVAL;
#endif
ROSArduinoBridge.ino 的 runCommand()函数中
#ifdef USE_BASEcase READ_ENCODERS:Serial.print(readEncoder(LEFT));Serial.print( );Serial.println(readEncoder(RIGHT));break;case RESET_ENCODERS:resetEncoders();resetPID();Serial.println(OK);break;case MOTOR_SPEEDS: //---------------------------------------------/* Reset the auto stop timer */lastMotorCommand millis();if (arg1 0 arg2 0) {setMotorSpeeds(0, 0);resetPID();moving 0;}else moving 1;//设置左右电机目标转速分别为参数1和参数2leftPID.TargetTicksPerFrame arg1;rightPID.TargetTicksPerFrame arg2;Serial.println(OK); break;case UPDATE_PID:while ((str strtok_r(p, :, p)) ! \0) {pid_args[i] atoi(str);i;}Kp pid_args[0];Kd pid_args[1];Ki pid_args[2];Ko pid_args[3];Serial.println(OK);break;
#endif
ROSArduinoBridge.ino 的 loop()函数中
#ifdef USE_BASE//如果当前时刻大于 nextPID,那么就执行PID调速并在 nextPID 上自增一个PID调试周期if (millis() nextPID) {updatePID();nextPID PID_INTERVAL;}// Check to see if we have exceeded the auto-stop intervalif ((millis() - lastMotorCommand) AUTO_STOP_INTERVAL) {;setMotorSpeeds(0, 0);moving 0;}
#endif
diff_controller.h 中的PID调试代码
/* Functions and type-defs for PID control.Taken mostly from Mike Fergusons ArbotiX code which lives at:http://vanadium-ros-pkg.googlecode.com/svn/trunk/arbotix/
*//* PID setpoint info For a Motor */
typedef struct {double TargetTicksPerFrame; // target speed in ticks per frame 目标转速long Encoder; // encoder count 编码器计数long PrevEnc; // last encoder count 上次的编码器计数/** Using previous input (PrevInput) instead of PrevError to avoid derivative kick,* see http://brettbeauregard.com/blog/2011/04/improving-the-beginner%E2%80%99s-pid-derivative-kick/*/int PrevInput; // last input//int PrevErr; // last error/** Using integrated term (ITerm) instead of integrated error (Ierror),* to allow tuning changes,* see http://brettbeauregard.com/blog/2011/04/improving-the-beginner%E2%80%99s-pid-tuning-changes/*///int Ierror;int ITerm; //integrated termlong output; // last motor setting
}
SetPointInfo;SetPointInfo leftPID, rightPID;/* PID Parameters */
int Kp 20;
int Kd 12;
int Ki 0;
int Ko 50;unsigned char moving 0; // is the base in motion?/*
* Initialize PID variables to zero to prevent startup spikes
* when turning PID on to start moving
* In particular, assign both Encoder and PrevEnc the current encoder value
* See http://brettbeauregard.com/blog/2011/04/improving-the-beginner%E2%80%99s-pid-initialization/
* Note that the assumption here is that PID is only turned on
* when going from stop to moving, thats why we can init everything on zero.
*/
void resetPID(){leftPID.TargetTicksPerFrame 0.0;leftPID.Encoder readEncoder(LEFT);leftPID.PrevEnc leftPID.Encoder;leftPID.output 0;leftPID.PrevInput 0;leftPID.ITerm 0;rightPID.TargetTicksPerFrame 0.0;rightPID.Encoder readEncoder(RIGHT);rightPID.PrevEnc rightPID.Encoder;rightPID.output 0;rightPID.PrevInput 0;rightPID.ITerm 0;
}/* PID routine to compute the next motor commands */
//左右电机具体调试函数
void doPID(SetPointInfo * p) {long Perror;long output;int input;//Perror p-TargetTicksPerFrame - (p-Encoder - p-PrevEnc);input p-Encoder - p-PrevEnc;Perror p-TargetTicksPerFrame - input;//根据 input 绘图//Serial.println(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 (Kp * Perror - Kd * (input - p-PrevInput) p-ITerm) / Ko;p-PrevEnc p-Encoder;output p-output;// Accumulate Integral error *or* Limit output.// Stop accumulating when output saturatesif (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 Ki * Perror;p-output output;p-PrevInput input;
}/* Read the encoder values and call the PID routine */
//PID调试
void updatePID() {/* Read the encoders */leftPID.Encoder readEncoder(LEFT);rightPID.Encoder readEncoder(RIGHT);/* If were 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*/if (leftPID.PrevInput ! 0 || rightPID.PrevInput ! 0) resetPID();return;}/* Compute PID update for each motor */doPID(rightPID);doPID(leftPID);/* Set the motor speeds accordingly */setMotorSpeeds(leftPID.output, rightPID.output);
}
2.PID调试
调试时需要在 diff_controller.h 中打印 input 的值然后通过串口绘图器输入命令 m 参数1 参数2根据绘图结果调试Kp、Ki和Kd的值。 调试时可以先调试单个电机的PID比如可以先注释 doPID(rightPID)PID算法不同即便算法相同如果参与运算的数据单位不同都会导致不同的调试结果不可以直接复用之前的调试结果。
PID调试技巧可以参考之前介绍。
