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SimpleDirectedControlSampler.cpp
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00034 
00035 /* Author: Ioan Sucan */
00036 
00037 #include "ompl/control/SimpleDirectedControlSampler.h"
00038 #include "ompl/control/SpaceInformation.h"
00039 
00040 ompl::control::SimpleDirectedControlSampler::SimpleDirectedControlSampler(const SpaceInformation *si, unsigned int k) :
00041     DirectedControlSampler(si), cs_(si->allocControlSampler()), numControlSamples_(k)
00042 {
00043 }
00044 
00045 ompl::control::SimpleDirectedControlSampler::~SimpleDirectedControlSampler(void)
00046 {
00047 }
00048 
00049 unsigned int ompl::control::SimpleDirectedControlSampler::sampleTo(Control *control, const base::State *source, const base::State *target)
00050 {
00051     return getBestControl(control, source, target, NULL);
00052 }
00053 
00054 unsigned int ompl::control::SimpleDirectedControlSampler::sampleTo(Control *control, const Control *previous, const base::State *source, const base::State *target)
00055 {
00056     return getBestControl(control, source, target, previous);
00057 }
00058 
00059 unsigned int ompl::control::SimpleDirectedControlSampler::getBestControl (Control *control, const base::State *source, const base::State *target, const Control *previous)
00060 {
00061     // Sample the first control
00062     if (previous)
00063         cs_->sampleNext(control, previous, source);
00064     else
00065         cs_->sample(control, source);
00066 
00067     const double minDuration = si_->getMinControlDuration();
00068     const double maxDuration = si_->getMaxControlDuration();
00069 
00070     unsigned int steps = cs_->sampleStepCount(minDuration, maxDuration);
00071 
00072     if (numControlSamples_ > 1)
00073     {
00074         Control     *tempControl = si_->allocControl();
00075         base::State *tempState   = si_->allocState();
00076 
00077         // Propagate the first control, and find how far it is from the target state
00078         si_->propagateWhileValid(source, control, steps, tempState);
00079         double bestDistance = si_->distance(tempState, target);
00080 
00081         // Sample k-1 more controls, and save the control that gets closest to target
00082         for (unsigned int i = 1; i < numControlSamples_; ++i)
00083         {
00084             unsigned int sampleSteps = cs_->sampleStepCount(minDuration, maxDuration);
00085             if (previous)
00086                 cs_->sampleNext(tempControl, previous, source);
00087             else
00088                 cs_->sample(tempControl, source);
00089 
00090             si_->propagateWhileValid(source, tempControl, sampleSteps, tempState);
00091             double tempDistance = si_->distance(tempState, target);
00092             if (tempDistance < bestDistance)
00093             {
00094                 si_->copyControl(control, tempControl);
00095                 bestDistance = tempDistance;
00096                 steps = sampleSteps;
00097             }
00098         }
00099 
00100         si_->freeControl(tempControl);
00101         si_->freeState(tempState);
00102     }
00103     return steps;
00104 }