SimpleDirectedControlSampler.cpp
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34 
35 /* Author: Ioan Sucan */
36 
37 #include "ompl/control/SimpleDirectedControlSampler.h"
38 #include "ompl/control/SpaceInformation.h"
39 
41  DirectedControlSampler(si), cs_(si->allocControlSampler()), numControlSamples_(k)
42 {
43 }
44 
45 ompl::control::SimpleDirectedControlSampler::~SimpleDirectedControlSampler()
46 {
47 }
48 
50 {
51  return getBestControl(control, source, dest, NULL);
52 }
53 
54 unsigned int ompl::control::SimpleDirectedControlSampler::sampleTo(Control *control, const Control *previous, const base::State *source, base::State *dest)
55 {
56  return getBestControl(control, source, dest, previous);
57 }
58 
59 unsigned int ompl::control::SimpleDirectedControlSampler::getBestControl (Control *control, const base::State *source, base::State *dest, const Control *previous)
60 {
61  // Sample the first control
62  if (previous)
63  cs_->sampleNext(control, previous, source);
64  else
65  cs_->sample(control, source);
66 
67  const unsigned int minDuration = si_->getMinControlDuration();
68  const unsigned int maxDuration = si_->getMaxControlDuration();
69 
70  unsigned int steps = cs_->sampleStepCount(minDuration, maxDuration);
71  // Propagate the first control, and find how far it is from the target state
72  base::State *bestState = si_->allocState();
73  steps = si_->propagateWhileValid(source, control, steps, bestState);
74 
75  if (numControlSamples_ > 1)
76  {
77  Control *tempControl = si_->allocControl();
78  base::State *tempState = si_->allocState();
79  double bestDistance = si_->distance(bestState, dest);
80 
81  // Sample k-1 more controls, and save the control that gets closest to target
82  for (unsigned int i = 1; i < numControlSamples_; ++i)
83  {
84  unsigned int sampleSteps = cs_->sampleStepCount(minDuration, maxDuration);
85  if (previous)
86  cs_->sampleNext(tempControl, previous, source);
87  else
88  cs_->sample(tempControl, source);
89 
90  sampleSteps = si_->propagateWhileValid(source, tempControl, sampleSteps, tempState);
91  double tempDistance = si_->distance(tempState, dest);
92  if (tempDistance < bestDistance)
93  {
94  si_->copyState(bestState, tempState);
95  si_->copyControl(control, tempControl);
96  bestDistance = tempDistance;
97  steps = sampleSteps;
98  }
99  }
100 
101  si_->freeState(tempState);
102  si_->freeControl(tempControl);
103  }
104 
105  si_->copyState(dest, bestState);
106  si_->freeState(bestState);
107 
108  return steps;
109 }
unsigned int getMinControlDuration() const
Get the minimum number of steps a control is propagated for.
unsigned int propagateWhileValid(const base::State *state, const Control *control, int steps, base::State *result) const
Propagate the model of the system forward, starting at a given state, with a given control...
Definition of an abstract control.
Definition: Control.h:48
void freeState(State *state) const
Free the memory of a state.
virtual unsigned int sampleTo(Control *control, const base::State *source, base::State *dest)
Sample a control given that it will be applied to state state and the intention is to reach state des...
virtual unsigned int getBestControl(Control *control, const base::State *source, base::State *dest, const Control *previous)
Samples numControlSamples_ controls, and returns the control that brings the system the closest to ta...
State * allocState() const
Allocate memory for a state.
Control * allocControl() const
Allocate memory for a control.
SimpleDirectedControlSampler(const SpaceInformation *si, unsigned int k=1)
Constructor takes the state space to construct samples for as argument Optionally, a k value can be given to indicate the number of controls to try when directing a system toward a specific state. Default value is 1.
void copyControl(Control *destination, const Control *source) const
Copy a control to another.
void copyState(State *destination, const State *source) const
Copy a state to another.
unsigned int getMaxControlDuration() const
Get the maximum number of steps a control is propagated for.
ControlSamplerPtr cs_
An instance of the control sampler.
Abstract definition of a directed control sampler. Motion planners that need to sample controls that ...
Definition of an abstract state.
Definition: State.h:50
const SpaceInformation * si_
The space information this sampler operates on.
void freeControl(Control *control) const
Free the memory of a control.
Space information containing necessary information for planning with controls. setup() needs to be ca...
unsigned int numControlSamples_
The number of controls to sample when finding the best control.
double distance(const State *state1, const State *state2) const
Compute the distance between two states.