ArActionLimiterBackwards.cpp

/*
MobileRobots Advanced Robotics Interface for Applications (ARIA)
Copyright (C) 2004, 2005 ActivMedia Robotics LLC
Copyright (C) 2006, 2007 MobileRobots Inc.

     This program is free software; you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
     the Free Software Foundation; either version 2 of the License, or
     (at your option) any later version.

     This program is distributed in the hope that it will be useful,
     but WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     GNU General Public License for more details.

     You should have received a copy of the GNU General Public License
     along with this program; if not, write to the Free Software
     Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

If you wish to redistribute ARIA under different terms, contact 
MobileRobots for information about a commercial version of ARIA at 
robots@mobilerobots.com or 
MobileRobots Inc, 19 Columbia Drive, Amherst, NH 03031; 800-639-9481
*/

#include "ArExport.h"
#include "ariaOSDef.h"
#include "ArActionLimiterBackwards.h"
#include "ArRobot.h"

AREXPORT ArActionLimiterBackwards::ArActionLimiterBackwards(
    const char *name, double stopDistance, double slowDistance, 
    double maxBackwardsSpeed, double widthRatio) :
  ArAction(name,
       "Slows the robot down so as not to hit anything in front of it.")
{
  setNextArgument(ArArg("stop distance", &myStopDist, 
            "Distance at which to stop. (mm)"));
  myStopDist = stopDistance;

  setNextArgument(ArArg("slow distance", &mySlowDist, 
            "Distance at which to slow down. (mm)"));
  mySlowDist = slowDistance;

  setNextArgument(ArArg("maximum backwards speed", &myMaxBackwardsSpeed, 
             "Maximum backwards speed, scales from this to 0 at stopDistance (-mm/sec)"));
  myMaxBackwardsSpeed = maxBackwardsSpeed;

  setNextArgument(ArArg("width ratio", &myWidthRatio, 
             "The ratio of robot width to how wide an area to check (ratio)"));
  myWidthRatio = widthRatio;
  
}

AREXPORT ArActionLimiterBackwards::~ArActionLimiterBackwards()
{

}

AREXPORT ArActionDesired *
ArActionLimiterBackwards::fire(ArActionDesired currentDesired)
{
  double dist;
  double maxVel;
  
  double slowStopDist = ArUtil::findMax(myStopDist, mySlowDist);
  

  myDesired.reset();
  dist = myRobot->checkRangeDevicesCurrentBox(-myRobot->getRobotLength()/2,
                          -(myRobot->getRobotWidth()/2.0 * 
                        myWidthRatio),
                   slowStopDist + (-myRobot->getRobotLength()),
                          (myRobot->getRobotWidth()/2.0 * 
                           myWidthRatio));
  dist -= myRobot->getRobotRadius();
  if (dist < -myStopDist)
  {
    //printf("backwards stop\n");
    myDesired.setMaxNegVel(0);
    return &myDesired;
  }
  if (dist > -mySlowDist)
  {
    //printf("backwards nothing\n");
    myDesired.setMaxNegVel(-ArMath::fabs(myMaxBackwardsSpeed));
    return &myDesired;
  }
      
            
  maxVel = -ArMath::fabs(myMaxBackwardsSpeed) * ((-dist - myStopDist) / (mySlowDist - myStopDist));
  //printf("Neg Max vel %f (stopdist %.1f slowdist %.1f slowspeed %.1f\n", maxVel,   myStopDist, mySlowDist, myMaxBackwardsSpeed);
  myDesired.setMaxNegVel(maxVel);
  return &myDesired;
  
}

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