BipedalLocomotion::IK::JointLimitsTask class
#include <BipedalLocomotion/IK/JointLimitsTask.h>

JointLimitsTask is a concrete implementation of the Task.

Please use this element if you want to ensure that the generated joint velocity will consider the joints position limits. The task represents the following equation

\[ \dot{s}_{-} \preceq \begin{bmatrix} 0_6 & I_n \end{bmatrix} \nu \preceq \dot{s}_{+} \]

where $0_6$ and $I_n$ are the zero and the identity matrix. $\dot{s} _{-}$ and $\dot{s} _{+}$ are chosen such that robot stays within its mechanical range of motion. Following (Kanoun, 2011), we set $\dot{s}_{-}$ and $\dot{s}_{+}$ as follows

\[ \dot{s}_{-} = k_{\text{lim}} \frac{s_{-} - s}{dt} \quad \dot{s}_{+} = k_{\text{lim}} \frac{s_{+} - s}{dt} \]

where ${s}_{-}$ and ${s} _{+}$ are the joints mechanical limits, and $k_{\text{lim}}$ is a proportional postive gain lower than 1. $k_{\text{lim}}$ , for instance, denotes that a joint angle update will not increase by more than half the distance between the current joint value and its boundaries.

Base classes

struct IKLinearTask
IKLinearTask specializes a LinearTask in the case of Inverse Kinematics.

Public functions

auto initialize(std::weak_ptr<const ParametersHandler::IParametersHandler> paramHandler) -> bool override
Initialize the task.
auto setKinDyn(std::shared_ptr<iDynTree::KinDynComputations> kinDyn) -> bool override
Set the kinDynComputations object.
auto setVariablesHandler(const System::VariablesHandler& variablesHandler) -> bool override
Set the set of variables required by the task.
auto update() -> bool override
Update the content of the element.
auto size() const -> std::size_t override
Get the size of the task.
auto type() const -> Type override
The JointsLimitsTask is an inequality task.
auto isValid() const -> bool override
Determines the validity of the objects retrieved with getA() and getB()

Function documentation

bool BipedalLocomotion::IK::JointLimitsTask::initialize(std::weak_ptr<const ParametersHandler::IParametersHandler> paramHandler) override

Initialize the task.

Parameters
paramHandler pointer to the parameters handler.
Returns True in case of success, false otherwise. Where the generalized robot velocity is a vector containing the base spatial-velocity (expressed in mixed representation) and the joint velocities.

bool BipedalLocomotion::IK::JointLimitsTask::setKinDyn(std::shared_ptr<iDynTree::KinDynComputations> kinDyn) override

Set the kinDynComputations object.

Parameters
kinDyn pointer to a kinDynComputations object.
Returns True in case of success, false otherwise.

bool BipedalLocomotion::IK::JointLimitsTask::setVariablesHandler(const System::VariablesHandler& variablesHandler) override

Set the set of variables required by the task.

Parameters
variablesHandler reference to a variables handler.
Returns True in case of success, false otherwise.

The variables are stored in the System::VariablesHandler.

bool BipedalLocomotion::IK::JointLimitsTask::update() override

Update the content of the element.

Returns True in case of success, false otherwise.

std::size_t BipedalLocomotion::IK::JointLimitsTask::size() const override

Get the size of the task.

Returns the size of the task.

(I.e the number of rows of the vector b)

Type BipedalLocomotion::IK::JointLimitsTask::type() const override

The JointsLimitsTask is an inequality task.

Returns the size of the task.

bool BipedalLocomotion::IK::JointLimitsTask::isValid() const override

Determines the validity of the objects retrieved with getA() and getB()

Returns True if the objects are valid, false otherwise.