Author: Yu Hang He Email: hey6@unlv.nevada.edu
Date: Last modified on <11/20/17>
Keywords: Darwin OP 2, C Programming, Robotis OP 2

This tutorial will demonstrate how to program Darwin OP 2 to walk backward. The walking algorithm for backward motion is included in Darwin OP 2's source code by Robotis. However, there is no on-line, or barely any, documentation of this process. This tutorial take approximately 1 hour to complete.

This tutorial's motivation is to demonstrate how to program Darwin OP 2 to walk toward a target. This tutorial assumes the reader has the following background and interests:

• Familiar with handling Darwin OP 2
• Familiar with Cplusplus/C programming language
• Familiar with Cplusplus/C codes on Darwin OP 2

The rest of this tutorial is presented as follows:

• Programming
• Demonstration
• Final Words

Following a target can be accomplished through BallFollower Class. There is a tutorial on Robotis' online manual that may provide further detail.
This tutorial will only demonstrate parts of program that needs modification to include program Darwin OP 2 to walk toward a target.

| main.cpp

#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <libgen.h>
#include "LinuxDARwIn.h"
 
#define INI_FILE_PATH       "../../../../Data/config.ini"
#define U2D_DEV_NAME        "/dev/ttyUSB0"
 
using namespace Robot;
 
 
void change_current_dir()
{
    char exepath[1024] = {0};
    if(readlink("/proc/self/exe", exepath, sizeof(exepath)) != -1)
        chdir(dirname(exepath));
}
 
int main(void)
{
    printf( "\n===== Walk Backward Tutorial for DARwIn =====\n\n");
 
    change_current_dir();
 
    minIni* ini = new minIni(INI_FILE_PATH);
 
	//////////////////// Framework Initialize ////////////////////////////
	LinuxCM730 linux_cm730(U2D_DEV_NAME);
	CM730 cm730(&linux_cm730);
	if(MotionManager::GetInstance()->Initialize(&cm730) == false)
	{
		printf("Fail to initialize Motion Manager!\n");
			return 0;
	}
    MotionManager::GetInstance()->LoadINISettings(ini);
    Walking::GetInstance()->LoadINISettings(ini);
 
	MotionManager::GetInstance()->AddModule((MotionModule*)Head::GetInstance());
	MotionManager::GetInstance()->AddModule((MotionModule*)Walking::GetInstance());
    LinuxMotionTimer *motion_timer = new LinuxMotionTimer(MotionManager::GetInstance());
    motion_timer->Start();
	/////////////////////////////////////////////////////////////////////
 
	int n = 0;
	int param[JointData::NUMBER_OF_JOINTS * 5];
	int wGoalPosition, wStartPosition, wDistance;
 
	for(int id=JointData::ID_R_SHOULDER_PITCH; id<JointData::NUMBER_OF_JOINTS; id++)
	{
		wStartPosition = MotionStatus::m_CurrentJoints.GetValue(id);
		wGoalPosition = Walking::GetInstance()->m_Joint.GetValue(id);
		if( wStartPosition > wGoalPosition )
			wDistance = wStartPosition - wGoalPosition;
		else
			wDistance = wGoalPosition - wStartPosition;
 
		wDistance >>= 2;
		if( wDistance < 8 )
			wDistance = 8;
 
		param[n++] = id;
		param[n++] = CM730::GetLowByte(wGoalPosition);
		param[n++] = CM730::GetHighByte(wGoalPosition);
		param[n++] = CM730::GetLowByte(wDistance);
		param[n++] = CM730::GetHighByte(wDistance);
	}
	cm730.SyncWrite(MX28::P_GOAL_POSITION_L, 5, JointData::NUMBER_OF_JOINTS - 1, param);
 
	printf("Press the ENTER key to begin!\n");
	getchar();
 
    Head::GetInstance()->m_Joint.SetEnableHeadOnly(true, true);
    Walking::GetInstance()->m_Joint.SetEnableBodyWithoutHead(true, true);
	MotionManager::GetInstance()->SetEnable(true);
 
    while(1)
    {
 
	    if(Action::GetInstance()->IsRunning() == 0)
            {
		Head::GetInstance()->m_Joint.SetEnableHeadOnly(true, true);
                Walking::GetInstance()->m_Joint.SetEnableBodyWithoutHead(true, true);
 
                if(Walking::GetInstance()->IsRunning() == false){
                Walking::GetInstance()->X_MOVE_AMPLITUDE = -15.0;
                Walking::GetInstance()->A_MOVE_AMPLITUDE = 0.0;
                Walking::GetInstance()->Start();
                }
 
		Walking::GetInstance()->X_MOVE_AMPLITUDE = -15.0;
		Walking::GetInstance()->A_MOVE_AMPLITUDE = 0.0;
	     }
 
    }
 
    return 0;
}

| MakeFile

TARGET = walk_backward
 
INCLUDE_DIRS = -I../../../include -I../../../../Framework/include
 
CXX = g++
CXXFLAGS += -O2 -DLINUX -Wall $(INCLUDE_DIRS)
#CXXFLAGS += -O2 -DDEBUG -DLINUX -Wall $(INCLUDE_DIRS)
LFLAGS += -lpthread -ljpeg -lrt
 
OBJECTS =   main.o
 
all: $(TARGET)
 
clean:
	rm -f *.a *.o $(TARGET) core *~ *.so *.lo
 
libclean:
	make -C ../../../build clean
 
distclean: clean libclean
 
darwin.a:
	make -C ../../../build
 
$(TARGET): darwin.a $(OBJECTS)
	$(CXX) $(CFLAGS) $(OBJECTS) ../../../lib/darwin.a -o $(TARGET) $(LFLAGS)
	chmod 755 $(TARGET)
 
# useful to make a backup "make tgz"
tgz: clean
	mkdir -p backups
	tar czvf ./backups/ball_following_`date +"%Y_%m_%d_%H.%M.%S"`.tgz --exclude backups *

In this demonstration, I created a new mode called Sprint mode following the previous step and successfully execute it on Darwin OP 2.

This tutorial's objective was to demonstrate how to program Darwin OP 2 to walk toward target.

For questions, clarifications, etc, Email: hey6@unlv.nevada.edu