swing_constraint.cc
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29 
32 
33 namespace towr {
34 
35 SwingConstraint::SwingConstraint (std::string ee_motion)
36  :ConstraintSet(kSpecifyLater, "swing-" + ee_motion)
37 {
38  ee_motion_id_ = ee_motion;
39 }
40 
41 void
43 {
45 
46  pure_swing_node_ids_ = ee_motion_->GetIndicesOfNonConstantNodes();
47 
48  // constrain xy position and velocity of every swing node
49  int constraint_count = pure_swing_node_ids_.size()*Node::n_derivatives*k2D;
50 
51  SetRows(constraint_count);
52 }
53 
56 {
57  VectorXd g(GetRows());
58 
59  int row = 0;
60  auto nodes = ee_motion_->GetNodes();
61  for (int node_id : pure_swing_node_ids_) {
62  // assumes two splines per swingphase and starting and ending in stance
63  auto curr = nodes.at(node_id);
64 
65  Vector2d prev = nodes.at(node_id-1).p().topRows<k2D>();
66  Vector2d next = nodes.at(node_id+1).p().topRows<k2D>();
67 
68  Vector2d distance_xy = next - prev;
69  Vector2d xy_center = prev + 0.5*distance_xy;
70  Vector2d des_vel_center = distance_xy/t_swing_avg_; // linear interpolation not accurate
71  for (auto dim : {X,Y}) {
72  g(row++) = curr.p()(dim) - xy_center(dim);
73  g(row++) = curr.v()(dim) - des_vel_center(dim);
74  }
75  }
76 
77  return g;
78 }
79 
82 {
84 }
85 
86 void
88  Jacobian& jac) const
89 {
90  if (var_set == ee_motion_->GetName()) {
91  int row = 0;
92  for (int node_id : pure_swing_node_ids_) {
93  for (auto dim : {X,Y}) {
94  // position constraint
95  jac.coeffRef(row, ee_motion_->GetOptIndex(NodesVariables::NodeValueInfo(node_id, kPos, dim))) = 1.0; // current node
96  jac.coeffRef(row, ee_motion_->GetOptIndex(NodesVariables::NodeValueInfo(node_id+1, kPos, dim))) = -0.5; // next node
97  jac.coeffRef(row, ee_motion_->GetOptIndex(NodesVariables::NodeValueInfo(node_id-1, kPos, dim))) = -0.5; // previous node
98  row++;
99 
100  // velocity constraint
101  jac.coeffRef(row, ee_motion_->GetOptIndex(NodesVariables::NodeValueInfo(node_id, kVel, dim))) = 1.0; // current node
102  jac.coeffRef(row, ee_motion_->GetOptIndex(NodesVariables::NodeValueInfo(node_id+1, kPos, dim))) = -1.0/t_swing_avg_; // next node
103  jac.coeffRef(row, ee_motion_->GetOptIndex(NodesVariables::NodeValueInfo(node_id-1, kPos, dim))) = +1.0/t_swing_avg_; // previous node
104  row++;
105  }
106  }
107  }
108 }
109 
110 } /* namespace towr */
void InitVariableDependedQuantities(const VariablesPtr &x) override
static const Bounds BoundZero
Composite::Ptr VariablesPtr
void FillJacobianBlock(std::string var_set, Jacobian &) const override
Eigen::Vector2d Vector2d
Eigen::VectorXd VectorXd
SwingConstraint(std::string ee_motion_id)
Links the swing constraint with current foot variables.
int GetRows() const
Semantic information associated with a scalar node value.
static constexpr int k2D
VectorXd GetValues() const override
NodesVariablesPhaseBased::Ptr ee_motion_
void SetRows(int num_rows)
std::vector< int > pure_swing_node_ids_
Eigen::SparseMatrix< double, Eigen::RowMajor > Jacobian
VecBound GetBounds() const override
Nodes that are associated to either swing or stance phases.
static const int n_derivatives
value and first derivative.
Definition: state.h:109
std::vector< Bounds > VecBound
Eigen::VectorXd VectorXd


towr
Author(s): Alexander W. Winkler
autogenerated on Mon Feb 28 2022 23:54:22