joint_limits_interface::PositionJointSoftLimitsHandle Class Reference

A handle used to enforce position and velocity limits of a position-controlled joint. More...

#include <joint_limits_interface.hpp>

Inheritance diagram for joint_limits_interface::PositionJointSoftLimitsHandle:

Collaboration diagram for joint_limits_interface::PositionJointSoftLimitsHandle:

Public Member Functions
	PositionJointSoftLimitsHandle (const hardware_interface::JointHandle &jposh, const hardware_interface::JointHandle &jcmdh, const joint_limits_interface::JointLimits &limits, const joint_limits_interface::SoftJointLimits &soft_limits)
void	enforce_limits (const rclcpp::Duration &period) override
	Enforce position and velocity limits for a joint subject to soft limits.
Public Member Functions inherited from joint_limits_interface::JointSoftLimitsHandle
	JointSoftLimitsHandle (const hardware_interface::JointHandle &jposh, const hardware_interface::JointHandle &jcmdh, const JointLimits &limits, const SoftJointLimits &soft_limits)
	JointSoftLimitsHandle (const hardware_interface::JointHandle &jposh, const hardware_interface::JointHandle &jvelh, const hardware_interface::JointHandle &jcmdh, const JointLimits &limits, const SoftJointLimits &soft_limits)
Public Member Functions inherited from joint_limits_interface::JointLimitHandle
	JointLimitHandle (const hardware_interface::JointHandle &jposh, const hardware_interface::JointHandle &jcmdh, const JointLimits &limits)
	JointLimitHandle (const hardware_interface::JointHandle &jposh, const hardware_interface::JointHandle &jvelh, const hardware_interface::JointHandle &jcmdh, const JointLimits &limits)
std::string	get_name () const
virtual void	reset ()
	Clear stored state, causing it to reset next iteration.

Additional Inherited Members
Protected Member Functions inherited from joint_limits_interface::JointLimitHandle
double	get_velocity (const rclcpp::Duration &period) const
	Return velocity for limit calculations.
Protected Attributes inherited from joint_limits_interface::JointSoftLimitsHandle
joint_limits_interface::SoftJointLimits	soft_limits_
Protected Attributes inherited from joint_limits_interface::JointLimitHandle
hardware_interface::JointHandle	jposh_
hardware_interface::JointHandle	jvelh_
hardware_interface::JointHandle	jcmdh_
joint_limits_interface::JointLimits	limits_
double	prev_pos_
double	prev_vel_

Detailed Description

A handle used to enforce position and velocity limits of a position-controlled joint.

This class implements a very simple position and velocity limits enforcing policy, and tries to impose the least amount of requisites on the underlying hardware platform. This lowers considerably the entry barrier to use it, but also implies some limitations.

Requisites

• Position (for non-continuous joints) and velocity limits specification.
• Soft limits specification. The k_velocity parameter is not used.

Open loop nature

Joint position and velocity limits are enforced in an open-loop fashion, that is, the command is checked for validity without relying on the actual position/velocity values.

• Actual position values are not used because in some platforms there might be a substantial lag between sending a command and executing it (propagate command to hardware, reach control objective, read from hardware).
• Actual velocity values are not used because of the above reason, and because some platforms might not expose trustworthy velocity measurements, or none at all.

The downside of the open loop behavior is that velocity limits will not be enforced when recovering from large position tracking errors. Only the command is guaranteed to comply with the limits specification.

Note

: This handle type is stateful, ie. it stores the previous position command to estimate the command velocity.

Member Function Documentation

enforce_limits()

void joint_limits_interface::PositionJointSoftLimitsHandle::enforce_limits ( const rclcpp::Duration &  period )

inlineoverridevirtual

Enforce position and velocity limits for a joint subject to soft limits.

If the joint has no position limits (eg. a continuous joint), only velocity limits will be enforced.

Parameters

[in]

period

Control period.

Implements joint_limits_interface::JointLimitHandle.

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The documentation for this class was generated from the following file:

• ros2_control/joint_limits_interface/include/joint_limits_interface/joint_limits_interface.hpp