Multi-contact Walking Pattern Generation based on Model Preview Control of 3D COM Accelerations

We present a multi-contact walking pattern generator based on preview-control of the 3D acceleration of the center of mass (COM). A key point in the design of our algorithm is the calculation of contact-stability constraints. Thanks to a mathematical observation on the algebraic nature of the frictional wrench cone, we show that the 3D volume of feasible COM accelerations is a always a downward-pointing cone. We reduce its computation to a convex hull of (dual) 2D points, for which optimal O(n log n) algorithms are readily available. This reformulation brings a significant speedup compared to previous methods, which allows us to compute time-varying contact-stability criteria fast enough for the control loop. Next, we propose a conservative trajectory-wide contact-stability criterion, which can be derived from COM-acceleration volumes at marginal cost and directly applied in a model-predictive controller. We finally implement this pipeline and exemplify it with the HRP-4 humanoid model in multi-contact dynamically walking scenarios

Analyzing Whole-Body Pose Transitions in Multi-Contact Motions

When executing whole-body motions, humans are able to use a large variety of support poses which not only utilize the feet, but also hands, knees and elbows to enhance stability. While there are many works analyzing the transitions involved in walking, very few works analyze human motion where more complex supports occur. In this work, we analyze complex support pose transitions in human motion involving locomotion and manipulation tasks (loco-manipulation). We have applied a method for the detection of human support contacts from motion capture data to a large-scale dataset of loco-manipulation motions involving multi-contact supports, providing a semantic representation of them. Our results provide a statistical analysis of the used support poses, their transitions and the time spent in each of them. In addition, our data partially validates our taxonomy of whole-body support poses presented in our previous work. We believe that this work extends our understanding of human motion for humanoids, with a long-term objective of developing methods for autonomous multi-contact motion planning.Comment: 8 pages, IEEE-RAS International Conference on Humanoid Robots (Humanoids) 201

Dynamic whole-body motion generation under rigid contacts and other unilateral constraints

The most widely used technique for generating wholebody motions on a humanoid robot accounting for various tasks and constraints is inverse kinematics. Based on the task-function approach, this class of methods enables the coordination of robot movements to execute several tasks in parallel and account for the sensor feedback in real time, thanks to the low computation cost. To some extent, it also enables us to deal with some of the robot constraints (e.g., joint limits or visibility) and manage the quasi-static balance of the robot. In order to fully use the whole range of possible motions, this paper proposes extending the task-function approach to handle the full dynamics of the robot multibody along with any constraint written as equality or inequality of the state and control variables. The definition of multiple objectives is made possible by ordering them inside a strict hierarchy. Several models of contact with the environment can be implemented in the framework. We propose a reduced formulation of the multiple rigid planar contact that keeps a low computation cost. The efficiency of this approach is illustrated by presenting several multicontact dynamic motions in simulation and on the real HRP-2 robot

Analyzing Whole-Body Pose Transitions in Multi-Contact Motions

Abstract-When executing whole-body motions, humans are able to use a large variety of support poses which not only utilize the feet, but also hands, knees and elbows to enhance stability. While there are many works analyzing the transitions involved in walking, very few works analyze human motion where more complex supports occur. In this work, we analyze complex support pose transitions in human motion involving locomotion and manipulation tasks (loco-manipulation). We have applied a method for the detection of human support contacts from motion capture data to a largescale dataset of loco-manipulation motions involving multicontact supports, providing a semantic representation of them. Our results provide a statistical analysis of the used support poses, their transitions and the time spent in each of them. In addition, our data partially validates our taxonomy of wholebody support poses presented in our previous work. We believe that this work extends our understanding of human motion for humanoids, with a long-term objective of developing methods for autonomous multi-contact motion planning

Motion Planning and Feedback Control of Simulated Robots in Multi-Contact Scenarios

Diese Dissertation präsentiert eine optimale steuerungsbasierte Architektur für die Bewegungsplanung und Rückkopplungssteuerung simulierter Roboter in Multikontaktszenarien. Bewegungsplanung und -steuerung sind grundlegende Bausteine für die Erstellung wirklich autonomer Roboter. Während in diesen Bereichen enorme Fortschritte für Manipulatoren mit festem Sockel und Radrobotern in den letzten Jahren erzielt wurden, besteht das Problem der Bewegungsplanung und -steuerung für Roboter mit Armen und Beinen immer noch ein ungelöstes Problem, das die Notwendigkeit effizienterer und robusterer Algorithmen belegt. In diesem Zusammenhang wird in dieser Dissertation eine Architektur vorgeschlagen, mit der zwei Hauptherausforderungen angegangen werden sollen, nämlich die effiziente Planung von Kontaktsequenzen und Ganzkörperbewegungen für Floating-Base-Roboter sowie deren erfolgreiche Ausführung mit Rückkopplungsregelungsstrategien, die Umgebungsunsicherheiten bewältigen könne

Déplacement d'un mannequin virtuel dans un environnement encombré : simulation de mouvement en intégrant les contraintes d'équilibre

This thesis was carried out in collaboration and co-funding of LSI of CEA/LIST and LBMC of IFSTTAR. The aim of the thesis was to study and develop a method for simulating the movement of a virtual manikin (VM) in a cluttered environment based on a priori knowledge. This thesis presents firstly motion capture (MoCap) experiments. The recorded data were analyzed to define some principles on human motion in cluttered environments. We then propose a general balance criterion and stability margin, based on a simplified model of VM. Then, we present a hierarchical framework that can generate and simulate dynamic movements of VM in a cluttered environment in three stages: a global trajectory of the center of mass (CoM) is generated at the global level to ensure balance in the VM's motion; then the trajectories of end-effectors (EE, ie feet, hands) and postures are generated locally under constraints of kinematics and collision avoidance; finally at the execution level, trajectories (CoM and EEs) and postures are used as references in a dynamic controller associated with VM so that the VM realizes the motion in a simulation. This framework is implemented in a car-ingress scenario in order to evaluate its performance and to suggest future improvementsCette thèse a été réalisée en collaboration et cofinancement impliquant le LSI du CEA/LIST et le LBMC de l'IFSTTAR. L'objectif de thèse était d'étudier et de développer une méthode pour simuler les mouvements d'un mannequin virtuel (MV) dans un environnement encombré en s'appuyant sur des connaissances a priori. L'étude présente, dans un premier temps, des expériences de capture de mouvement (MoCap). Les données enregistrées ont été analysées afin de définir quelques principes sur les mouvements humains dans des environnements encombrés. Nous proposons ensuite un critère général d'équilibre et une marge de stabilité, sur la base d'un modèle simplifié du MV. Puis, nous présentons un framework hiérarchique pouvant générer et simuler des mouvements dynamiques du MV dans un environnement encombré en trois étapes : une trajectoire globale du centre de masse (CoM) est générée au niveau global afin d'assurer l'équilibre du MV durant son mouvement; puis au niveau local, les trajectoires des organes terminaux (OT, i.e. pieds, mains) et les postures sont générées localement sous des contraintes cinématiques et d'évitement de collisions; enfin au niveau de l'exécution, les trajectoires (CoM et OTs) et les postures sont utilisées comme références dans un contrôleur dynamique associé au MV. Enfin, ce framework est mis en œuvre dans un scenario d'entrée dans un véhicule pour évaluer ses performances et proposer des améliorations future

Organisation, Repräsentation und Analyse menschlicher Ganzkörperbewegung für die datengetriebene Bewegungsgenerierung bei humanoiden Robotern

Diese Arbeit präsentiert einen Ansatz zur datengetriebenen Bewegungsgenerierung für humanoide Roboter, der auf der Beobachtung und Analyse menschlicher Ganzkörperbewegungen beruht. Hierzu wird untersucht, wie erfasste Bewegungen repräsentiert, klassifiziert und in einer großskaligen Bewegungsdatenbank organisiert werden können. Die statistische Modellierung der Transitionen zwischen charakteristischen Ganzkörperposen ermöglicht im Anschluss die Generierung von Multi-Kontakt-Bewegungen

Potential Field Guide for Humanoid Multicontacts Acyclic Motion Planning

International audienceWe present a motion planning algorithm that computes rough trajectories used by a contact-points planner as a guide to grow its search graph. We adapt collision-free motion planning algorithms to plan a path within the guide space, a submanifold of the configuration space included in the free space in which the configurations are subject to static stability constraint. We first discuss the definition of the guide space. Then we detail the different techniques and ideas involved: relevant C-space sampling for humanoid robot, task-driven projection process, static stability test based on polyhedral convex cones theory's double description method. We finally present results from our implementation of the algorithm