gait_generator.cc

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#include <towr/initialization/gait_generator.h>

#include <cassert>
#include <numeric>   // std::accumulate
#include <algorithm> // std::transform

#include <towr/initialization/monoped_gait_generator.h>
#include <towr/initialization/biped_gait_generator.h>
#include <towr/initialization/quadruped_gait_generator.h>

namespace towr {


GaitGenerator::Ptr
GaitGenerator::MakeGaitGenerator(int leg_count)
{
  switch (leg_count) {
    case 1: return std::make_shared<MonopedGaitGenerator>();   break;
    case 2: return std::make_shared<BipedGaitGenerator>();     break;
    case 4: return std::make_shared<QuadrupedGaitGenerator>(); break;
    default: assert(false); break; // Error: Not implemented
  }
}

GaitGenerator::VecTimes
GaitGenerator::GetPhaseDurations (double t_total, EE ee) const
{
  // scale total time tu t_total
  std::vector<double> durations;
  for (auto d : GetNormalizedPhaseDurations(ee))
    durations.push_back(d*t_total);

  return durations;
}

GaitGenerator::VecTimes
GaitGenerator::GetNormalizedPhaseDurations (EE ee) const
{
  auto v = GetPhaseDurations().at(ee); // shorthand
  double total_time = std::accumulate(v.begin(), v.end(), 0.0);
  std::transform(v.begin(), v.end(), v.begin(),
                 [total_time](double t_phase){ return t_phase/total_time;});

  return v;
}

GaitGenerator::FootDurations
GaitGenerator::GetPhaseDurations () const
{
  int n_ee = contacts_.front().size();
  VecTimes d_accumulated(n_ee, 0.0);

  FootDurations foot_durations(n_ee);
  for (int phase=0; phase<contacts_.size()-1; ++phase) {
    ContactState curr = contacts_.at(phase);
    ContactState next = contacts_.at(phase+1);

    for (int ee=0; ee<curr.size(); ++ee) {
      d_accumulated.at(ee) += times_.at(phase);

      // if contact will change in next phase, so this phase duration complete
      bool contacts_will_change = curr.at(ee) != next.at(ee);
      if (contacts_will_change)  {
        foot_durations.at(ee).push_back(d_accumulated.at(ee));
        d_accumulated.at(ee) = 0.0;
      }
    }
  }

  // push back last phase
  for (int ee=0; ee<contacts_.back().size(); ++ee)
    foot_durations.at(ee).push_back(d_accumulated.at(ee) + times_.back());


  return foot_durations;
}

bool
GaitGenerator::IsInContactAtStart (EE ee) const
{
  return contacts_.front().at(ee);
}

void
GaitGenerator::SetGaits (const std::vector<Gaits>& gaits)
{
  contacts_.clear();
  times_.clear();

  for (Gaits g : gaits) {
    auto info = GetGait(g);

    std::vector<double>       t = info.first;
    std::vector<ContactState> c = info.second;
    assert(t.size() == c.size()); // make sure every phase has a time

    times_.insert      (times_.end(), t.begin(), t.end());
    contacts_.insert(contacts_.end(), c.begin(), c.end());
  }
}

GaitGenerator::GaitInfo
GaitGenerator::RemoveTransition (const GaitInfo& g) const
{
  GaitInfo new_gait = g;

  // remove the final transition between strides
  // but ensure that last step duration is not cut off
  new_gait.first.pop_back();
  new_gait.first.back() += g.first.back();

  new_gait.second.pop_back();

  return new_gait;
}

} /* namespace towr */