Variables¶

Variables in the NLP are created through the following classes.

Nodes Variables¶

namespace gambol

class NodesVariables : public VariableSet¶

#include <NodesVariables.h>

Public Types

using Ptr = std::shared_ptr<NodesVariables>¶

using VectorXd = Eigen::VectorXd¶

Public Functions

NodesVariables(int n_nodes, int n_dim, std::string variable_id, NodeTimes::Ptr node_times)¶

virtual ~NodesVariables() = default¶

virtual NodeValueInfo GetNodeInfo(int opt_idx) const¶

Get info of node affected by one specific optimization variable.

Reverse of

GetOptIndex().

Return

The node value affected by this optimization variable.

Parameters

opt_idx: The index (=row) of the optimization variable.

virtual int GetOptIndex(const NodeValueInfo &nvi_des) const¶: Get opt index of specific value in the stacked opt. vector

virtual int GetOptIndex(int node_id, int dim) const¶

Get opt index of specific value, without the NVI struct

Get index of specific value inside the big stacked opt. vector

This function simply overload the basic and doesn’t require a NVI sturct.

VectorXd GetValues() const override¶: Pure optimization variables that define the nodes

void SetVariables(const VectorXd &x) override¶

Sets node positions from the optimization variables.

Parameters

x: The optimization variables.

void SetVariables(const std::vector<VectorXd> &nodes)¶: Set nodes directly

int GetDim() const¶: Return number of dimensions

int GetNumNodes() const¶: Return number of nodes

VecBound GetBounds() const override¶

Return: the bounds on position and velocity of each node and dimension.

const std::vector<VectorXd> &GetNodes() const¶

Return: All the nodes.

const VectorXd &GetNode(int k) const¶

Return: A single node.

VectorXd GetPoint(double t) const¶

Return: An interpolated point by time

void SetNode(int k, const VectorXd &value)¶: Set specific node value

const Jacobian GetNodeJacobian(int k) const¶

Returns a jacobian of a node w.r.t. the complete variable stack

Return jacobian of a node to the entire variable stack

Resulting jacobian has dim rows and dim * n_nodes columns. It will consist of zeros with an identity block.

Parameters

k: ID of the node to which the jacobian is for

void SetByLinearInterpolation(const VectorXd &initial_val, const VectorXd &final_val)¶

Sets nodes pos/vel equally spaced from initial to final position.

Parameters

initial_val: value of the first node.
final_val: value of the final node.

void SetConstantByPhase(const VectorXd &value, bool contact, const PhaseDurations::Ptr phases)¶

Sets node values for contact or flight phase.

Parameters

value: Constant value to be set
contact: Which phase to set
phases: Pointer to phases definition

void AddStartBound(const std::vector<int> &dimensions, const VectorXd &val)¶

Restricts the first node in the spline.

Parameters

dimensions: Which dimensions (x,y,z) should be restricted.
val: The values the fist node should be set to.

void AddFinalBound(const std::vector<int> &dimensions, const VectorXd &val)¶

Restricts the last node in the spline.

Parameters

dimensions: Which dimensions (x,y,z) should be restricted.
val: The values the last node should be set to.

void AddGlobalBound(const std::vector<int> &dimensions, const std::vector<std::pair<double, double>> &limits)¶

Restricts the last node in the spline.

Set constant limits to all joints

Parameters

dimensions: Which dimensions (x,y,z) should be restricted.
limits: The min and max values

This will overwrite Start and Final bounds!

Protected Attributes

VecBound bounds_¶: The bounds on the node values.

std::vector<VectorXd> nodes_¶: Actual nodes.

int n_dim_¶: Number of values (=dimensions_ per node.

NodeTimes::Ptr node_times_¶: Pointer to node timings.

Private Functions

void AddBounds(int node_id, const std::vector<int> &dim, const VectorXd &values)¶

Bounds a specific node variables.

Parameters

node_id: The ID of the node to bound.
dim: The dimension of the node to bound.
values: The values to set the bounds to.

void AddBound(const NodeValueInfo &node_info, double value)¶

Restricts a specific optimization variables.

Parameters

node_info: The specs of the optimization variables to restrict.
value: The value to set the bounds to.

struct NodeValueInfo¶

#include <NodesVariables.h>

Semantic information associated with a scalar node value

This includes all information except the actual value. This comes from the vector of optimization variables.

Public Functions

NodeValueInfo()¶

NodeValueInfo(int node_id, int node_dim)¶

int operator==(const NodeValueInfo &right) const¶

Public Members

int id_¶: ID of the associated node (0 =< id < number of nodes in spline).

int dim_¶: Dimension (x,y,z or joint id) of that derivative.

Node Times¶

namespace gambol

class NodeTimes¶

#include <NodeTimes.h>

Class for the times of each node (= collocation point)

This class is not essential, but it makes it easier to share a single instance of nodes times between different components.

Public Types

using Ptr = std::shared_ptr<NodeTimes>¶

using VecTimes = std::vector<double>¶

Public Functions

NodeTimes(const VecTimes &times)¶

Construct with entire list

Parameters

times: List of all node times

NodeTimes(double t_total, int n_nodes)¶

Construct based on total time and number of nodes

Construct with delta_t and number of nodes

Parameters

t_total: Total duration
n_nodes: Number of nodes

virtual ~NodeTimes() = default¶: Destructor

int GetNumberOfNodes() const¶: Return number of nodes

double GetTotalTime() const¶: Get total duration

double at(int k) const¶

Get single time

Get time of node k

const VecTimes &GetList() const¶

Get entire list

Get time of node k

int GetNodeId(double t_des) const¶

Return id of last node before given time

Return id of node right before given time

Return first node when t < 0 and last node when t > GetTotalTime().

int GetNodeId(double t_des, double &interpolation) const¶

Return id of last node and interpolation factor

Return id of node right before given time and the interpolation factor

Most right node is ignored. Method helps to interpolate random objects.

double GetDeltaT(int k) const¶

Get duration of this node and the next

Throws error when index is out of range

Private Members

VecTimes node_times_¶

Phase Durations¶

namespace gambol

class PhaseDurations¶

#include <PhaseDurations.h>

Class for durations of phases

This class determined whether a node is part of stance or swing.

Public Types

using Ptr = std::shared_ptr<PhaseDurations>¶

using VecDurations = std::vector<double>¶

Public Functions

PhaseDurations(const VecDurations &initial_durations, bool is_first_phase_in_contact)¶

Constructor

Parameters

timings: List of phase timings
is_first_phase_in_contact: true to start in contact

virtual ~PhaseDurations() = default¶

const VecDurations &GetPhaseDurations() const¶: Return durations

bool IsContactPhase(double t) const¶: Check whether in contact at a certain time

Private Members

VecDurations durations_¶: Actual durations.

double t_total_¶

bool initial_contact_state_¶: True if first phase in contact.

Variable Names¶

namespace gambol

namespace id¶

Variables

static const std::string joint_pos = "joint-pos"¶

static const std::string joint_vel = "joint-vel"¶

static const std::string torques = "torques"¶

static const std::string forces = "ee-forces_"¶

Nodes Holder¶

namespace gambol

struct NodesHolder¶

#include <NodesHolder.h>

Public Functions

NodesHolder() = default¶: Default constructor

NodesHolder(NodesVariables::Ptr joint_pos, NodesVariables::Ptr joint_vel, NodesVariables::Ptr torques, const std::vector<NodesVariables::Ptr> &ee_forces, const std::vector<PhaseDurations::Ptr> &phase_durations, NodeTimes::Ptr nodes_times)¶: Real constructor

virtual ~NodesHolder() = default¶: Desctructor

Public Members

NodesVariables::Ptr joint_pos_¶

NodesVariables::Ptr joint_vel_¶

NodesVariables::Ptr torques_¶

std::vector<NodesVariables::Ptr> ee_forces_¶

std::vector<PhaseDurations::Ptr> phase_durations_¶

NodeTimes::Ptr node_times_¶

Coordinates¶

Enums

enum Dim2D¶

Indicate dimension in 2D.

Values:

enumerator X_¶

enumerator Y_¶

enum Dim3D¶

Indicate dimension in 3D.

Values:

enumerator X¶

enumerator Y¶

enumerator Z¶