Only released in EOL distros:

See walk_tools on index.ros.org for more info including anything ROS 2 related.

humanoid_walk: halfsteps_pattern_generator | walk_interfaces | walk_msgs | walk_tools

Package Links

Dependencies (7)

Package Summary

Gathers tools providing useful computations when dealing with walking trajectory generation.

Author: Thomas Moulard
License: BSD
Source: git https://github.com/laas/humanoid_walk.git (branch: master)

humanoid_walk: halfsteps_pattern_generator | walk_interfaces | walk_msgs | walk_tools

Package Links

Dependencies (7)

Package Summary

Gathers tools providing useful computations when dealing with walking trajectory generation.

Author: Thomas Moulard
License: BSD
Source: git https://github.com/laas/humanoid_walk.git (branch: master)

Contents

ROS API

ROS API

ZMP estimation from force sensors

The most widely used balance criterion is the (virtual) Zero Momentum Point. When this point exits the robot polygon support, the robot start falling.

It is therefore interesting to monitor this point while the robot is running to make sure that it stays near its planned position.

A method to estimate the ZMP position is to measure the force applied on both feet and deduce the ZMP position from it. This tool realizes this computation and makes the following assuption:

the frame orientation of the force sensor data is the standard one (X forward, Y to the left and Z up),
two force sensors localized in the feet/ankles and synchronized data from them are available as geometry_msgs/WrenchStamped messages.
the robot is biped.

zmp_estimator

ZMP estimation node from feet force sensors

Subscribed Topics

~left_foot_wrench (geometry_msgs/WrenchStamped)

Left foot wrench measure by a force sensor.

~right_foot_wrench (geometry_msgs/WrenchStamped)

Right foot wrench measure by a force sensor.

Published Topics

zmp_estimated (geometry_msgs/Vector3Stamped)

ZMP position estimation.

Parameters

left_foot_wrench (string, default: left_foot)

Left foot wrench topic name

right_foot_wrench (string, default: right_foot)

Right foot wrench topic name

contact_threshold (Float64, default: 10)

Minimum force to consider that the foot touched the ground. By default 10 Newton. We recommend 2% of the robot total mass.

approximate_sync (Float64, default: 0.001)

Maximum allowed offset between the left and right foot wrench messages.

queue_size (Float64, default: 10)

Subscriber queue size

reference_frame (string, default: /world)

Id of the frame in which the foot positions are given.

left_foot_x (Float64, default: 0.)

Left foot X position in reference frame.

left_foot_y (Float64, default: 0.)

Left foot Y position in reference frame.

left_foot_z (Float64, default: 0.105)

Left foot Z position in reference frame.

right_foot_x (Float64, default: 0.)

Right foot X position in reference frame.

right_foot_y (Float64, default: 0.)

Right foot Y position in reference frame.

right_foot_z (Float64, default: 0.105)

Right foot Z position in reference frame.

For instance, you may run this script by typing:

   1 rosrun walk_tools zmp_monitor _left_foot_wrench:=/force_0 _right_foot_wrench:=/force_1

Effort monitor

During movement execution, effort monitoring on each actuator prevents robot dammage.

This script regularly checks that the current torques reported by the joint_states topic are lower than the limit indicated in the robot URDF model. If the effort is higher that 85% of the limit, a warning is issued. Warning and errors are reported using the ROS diagnostics stack.