terrain_constraint.cc

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#include <towr/constraints/terrain_constraint.h>


namespace towr {


TerrainConstraint::TerrainConstraint (const HeightMap::Ptr& terrain,
                                      std::string ee_motion)
    :ConstraintSet(kSpecifyLater, "terrain-" + ee_motion)
{
  ee_motion_id_ = ee_motion;
  terrain_ = terrain;
}

void
TerrainConstraint::InitVariableDependedQuantities (const VariablesPtr& x)
{
  ee_motion_ = x->GetComponent<NodesVariablesPhaseBased>(ee_motion_id_);

  // skip first node, b/c already constrained by initial stance
  for (int id=1; id<ee_motion_->GetNodes().size(); ++id)
    node_ids_.push_back(id);

  int constraint_count = node_ids_.size();
  SetRows(constraint_count);
}

Eigen::VectorXd
TerrainConstraint::GetValues () const
{
  VectorXd g(GetRows());

  auto nodes = ee_motion_->GetNodes();
  int row = 0;
  for (int id : node_ids_) {
    Vector3d p = nodes.at(id).p();
    g(row++) = p.z() - terrain_->GetHeight(p.x(), p.y());
  }

  return g;
}

TerrainConstraint::VecBound
TerrainConstraint::GetBounds () const
{
  VecBound bounds(GetRows());
  double max_distance_above_terrain = 1e20; // [m]

  int row = 0;
  for (int id : node_ids_) {
    if (ee_motion_->IsConstantNode(id))
      bounds.at(row) = ifopt::BoundZero;
    else
      bounds.at(row) = ifopt::Bounds(0.0, max_distance_above_terrain);
    row++;
  }

  return bounds;
}

void
TerrainConstraint::FillJacobianBlock (std::string var_set, Jacobian& jac) const
{
  if (var_set == ee_motion_->GetName()) {
    auto nodes = ee_motion_->GetNodes();
    int row = 0;
    for (int id : node_ids_) {
      int idx = ee_motion_->GetOptIndex(NodesVariables::NodeValueInfo(id, kPos, Z));
      jac.coeffRef(row, idx) = 1.0;

      Vector3d p = nodes.at(id).p();
      for (auto dim : {X,Y}) {
        int idx = ee_motion_->GetOptIndex(NodesVariables::NodeValueInfo(id, kPos, dim));
        jac.coeffRef(row, idx) = -terrain_->GetDerivativeOfHeightWrt(To2D(dim), p.x(), p.y());
      }
      row++;
    }
  }
}

} /* namespace towr */