Whole-body Control Research Articles

Whole-body control of anticipated and unanticipated sidestep manoeuvres in female and male team sport athletes

ABSTRACTThe purpose of this study was to investigate the influence of sex and planning time on spatial and temporal aspects of the whole-body centre of mass (CoM) mechanics during sidestepping performance. Seventeen female and 17 male collegiate team sport athletes completed seven anticipated and seven unanticipated sidestep trials during which three-dimensional CoM data were recorded. Female athletes had a reduced ability to reorient their CoM towards the desired direction of travel (lower medio-lateral and anterior-posterior CoM velocity) than their male counterparts, with reduced medial (closer to stance foot) and increased posterior positioning of CoM relative to the stance foot (p < 0.05). When planning time was limited, female and male athletes performed sidestepping with CoM further from the stance foot (more medial) and more anterior than in the anticipated condition (p < 0.05) at reduced medio-lateral velocities. Sex and condition control strategy differences were evident both in the preparatory phase and the stance phase. The current research draws attention to the foreseen benefits of training athletes, with particular emphasis on females, to direct CoM towards the desired direction of travel in the preparatory and stance phases within temporally constrained situations for improved performance.

229-OR: GLP-1 Infusions during Postprandial Insulin Clamps Enhance Muscle Microvascular Flow, Glucose Uptake, and Protein Anabolism in Older Men

Introduction: Ageing skeletal muscle becomes insulin resistant and atrophic. This is largely due to a failure in sequestering of amino acids and glucose from dietary intake into muscle protein and glycogen. GLP-1 possesses pleiotropic multi-organ properties and its receptor is expressed and exert effects in muscle tissue(s) e.g., endothelium. We hypothesized GLP-1 infusion would enhance muscle glucose uptake and bolster the trophic effects of an anabolic stimulus i.e., feeding. Methods: Eight men (71±1y) were studied in a cross-over trial. Basal measures were taken (first 3 h) prior to insulin (i.e., postprandial (fed-state)) and glucose (euglycaemic) clamps. Participants received I.V co-infusions of octreotide, Vamin 14-EF ±GLP-1. Four muscle biopsies were taken at 90-120 min intervals. Muscle protein turnover was quantified via A-V balance and direct incorporation of 13C6 phenylalanine via mass spectrometric techniques. GLP-1 and insulin were measured using Milliplex Map, ELISA kits. Muscle microvascular blood flow (MBF) was assessed via contrast enhanced ultrasound. Glucose handling was assayed by infusion rates and leg A-V balance. Results: GLP-1 (vs. -GLP-1 condition) augmented muscle protein synthesis (basal: 0.058±0.004%.h-1 vs. fed: 0.102±0.005%.h-1, p&amp;lt;0.01), net protein balance (p&amp;lt;0.0001 and p=0.03 vs. basal at 1.5h and 3h postprandial, respectively) and MBF (5±2 vs. 1.9±0.7 fold-change from basal respectively, p&amp;lt;0.01) - while increasing whole-body glucose uptake (AUC 17.0±1.7 vs. 11.4±1.8 mg.kg-1.180 min-1, p=0.02 with and without GLP, respectively). Muscle protein breakdown was equally suppressed with and without GLP-1. Leg glucose uptake was unchanged by GLP-1. Conclusions: The beneficial effects of GLP-1 upon whole-body glycaemic control are seemingly independent of muscle under fed-conditions. The pro-anabolic effect of GLP-1 in ageing is striking and requires further clinical and mechanistic research. Disclosure H. Abdulla: None. B.E. Phillips: None. M.C. Limb: None. D.J. Wilkinson: None. T. Jandova: None. J. Cegielski: None. J.J. Bass: None. D. Rankin: None. J.S. Lewis: None. J. Williams: None. K. Smith: None. I.R. Idris: None. P.J. Atherton: None. Funding Medical Research Council UK; Arthritis Research UK

Assessing and improving human movements using sensitivity analysis and digital human simulation

ABSTRACT Enhancing the performance of technical movements aims both at improving operational results and at reducing biomechanical demands. Advances in human biomechanics and modeling tools allow to evaluate human performance with more and more details. Finding the right modifications to improve the performance is, however, still addressed with extensive time consuming trial-and-error processes. This paper presents a framework for easily assessing human movements and automatically providing recommendations to improve their performances. An optimization-based whole-body controller is used to dynamically replay human movements from motion capture data, to evaluate existing movements. Automatic digital human simulations are then run to estimate performance indicators when the movement is performed in many different ways. Sensitivity indices are thereby computed to quantify the influence of postural parameters on the performance. Based on the results of the sensitivity analysis, recommendations for posture improvement are provided. The method is successfully validated on a drilling activity.

Passive Whole-Body Control for Quadruped Robots: Experimental Validation Over Challenging Terrain

We present experimental results using a passive whole-body control approach for quadruped robots that achieves dynamic locomotion while compliantly balancing the robot's trunk. We formulate the motion tracking as a quadratic program that takes into account the full robot rigid body dynamics, the actuation limits, the joint limits, and the contact interaction. We analyze the controller's robustness against inaccurate friction coefficient estimates and unstable footholds, as well as its capability to redistribute the load as a consequence of enforcing actuation limits. Additionally, we present practical implementation details gained from the experience with the real platform. Extensive experimental trials on the 90 kg hydraulically actuated quadruped robot validate the capabilities of this controller under various terrain conditions and gaits. The proposed approach is superior for accurate execution of highly dynamic motions with respect to the current state of the art.

Keep Rollin’—Whole-Body Motion Control and Planning for Wheeled Quadrupedal Robots

We show dynamic locomotion strategies for wheeled quadrupedal robots that combine the advantages of both walking and driving. The developed optimization framework tightly integrates the additional degrees of freedom introduced by the wheels. Our approach relies on a zero-moment point-based motion optimization which continuously updates reference trajectories. The reference motions are tracked by a hierarchical whole-body controller which computes optimal generalized accelerations and contact forces by solving a sequence of prioritized tasks including the nonholonomic rolling constraints. Our approach has been tested on ANYmal, a quadrupedal robot that is fully torque-controlled including the nonsteerable wheels attached to its legs. We conducted experiments on flat and inclined terrains as well as over steps, whereby we show that integrating the wheels into the motion control and planning framework results in intuitive motion trajectories, which enable more robust and dynamic locomotion compared to other wheeled-legged robots. Moreover, with a speed of 4 m/s and a reduction of the cost of transport by 83%, we prove the superiority of wheeled-legged robots compared to their legged counterparts.

Real-time humanoid whole-body remote control framework for imitating human motion based on kinematic mapping and motion constraints

ABSTRACTIn this paper, we propose a whole-body remote control framework that enables a robot to imitate human motion efficiently. The framework is divided into kinematic mapping and quadratic programming based whole-body inverse kinematics. In the kinematic mapping, the human motion obtained through a data acquisition device is transformed into a reference motion that is suitable for the robot to follow. To address differences in the kinematic configuration and dynamic properties of the robot and human, quadratic programming is used to calculate the joint angles of the robot considering self-collision, joint limits, and dynamic stability. To address dynamic stability, we use constraints based on the divergent component of motion and zero moment point in the linear inverted pendulum model. Simulation using Choreonoid and a locomotion experiment using the HUBO2+ demonstrate the performance of the proposed framework. The proposed framework has the potential to reduce the preview time or offline task computation time found in previous approaches and hence improve the similarity of human and robot motion while maintaining stability.

Bayesian Optimization for Whole-Body Control of High-Degree-of-Freedom Robots Through Reduction of Dimensionality

This letter aims to achieve automatic tuning of optimal parameters for whole-body control algorithms to achieve the best performance of high-DoF robots. Typically, the control parameters at a scale up to hundreds are often hand-tuned yielding sub-optimal performance. Bayesian optimization (BO) can be an option to automatically find optimal parameters. However, for high-dimensional problems, BO is often infeasible in realistic settings as we studied in this letter. Moreover, the data is too little to perform dimensionality reduction techniques, such as principal component analysis or partial least square. We hereby propose an alternating BO algorithm that iteratively learns the parameters of sub-spaces from the whole high-dimensional parametric space through interactive trials, resulting in sample efficiency and fast convergence. Furthermore, for the balancing and locomotion control of humanoids, we developed techniques of dimensionality reduction combined with the proposed ABO approach that demonstrated optimal parameters for robust whole-body control.

Speed and Acceleration Control for a Two Wheel-Leg Robot Based on Distributed Dynamic Model and Whole-Body Control

The control technique for generating whole body motions on wheel-leg robot for dynamic locomotion and balance is a challenging topic. In this paper, a whole body dynamic model is built. It consisted by the torso dynamic model, the wheel-leg dynamic model and the contact force constraint between the wheels and the ground. A whole body control frame is proposed which composed by a torso motion controller, two torque solvers, a slippage predictor and an online trajectory generator. The torso controller plans the coupling wrenches between wheel-legs and torso. The torque solvers for every wheel-leg compute joint torques based on the coupling wrenches computed from the torso controller synchronously. The contact forces can be calculated by the slippage predictor based on the joint torques, then a boolean signal will be transmitted to the online trajectories generator to indicate whether the friction cone constraint will be broken. The online trajectory generator can plan reasonable acceleration trajectory with different boolean signals. The efficiency of this control frame is illustrated by several simulations in virtual simulation environment.

Whole-Body Control of Humanoid Robot with 3D Multi-contact, Self Collided Posture and Degenerated DoF under Constraints of Contact Wrench and Motor Temperature

Whole-Body Control of Humanoid Robot with 3D Multi-contact, Self Collided Posture and Degenerated DoF under Constraints of Contact Wrench and Motor Temperature

Passivity Analysis and Control of Humanoid Robots on Movable Ground

Reliable and robust balancing controllers are key elements of whole-body control frameworks for humanoid robots. Passivity-based balancing controllers have been proposed and tested successfully in various scenarios involving different types of ground surfaces. This letter extends the passivity considerations for covering not only the robot and the controller but also the ground floor in order to guarantee an appropriate behavior, even when the underlying ground surface is not stable. The proposed extension is validated with experiments using the humanoid robot TOrque-controlled humanoid RObot (TORO).

Development of a Tele-Operated Rescue Robot for a Disaster Response

This paper proposes practical hardware design strategies and control methods for a rescue robot to save patients in disastrous environments. None of the existing humanoid robots have not shown the capability to efficiently execute rescue tasks for transferring a human to a safe place in a highly unstructured world. To resolve this problem a new form of powerful dual arm mechanism and hybrid tracked-legged mobile platform is developed and the motion is synthesized with dynamics based optimization and a modified hierarchical control scheme. These new design and control policies enable us to simultaneously enhance the manipulation performance and driving stability which have been verified through both in extensive numerical simulations and physical experiments where the rescue robot and whole-body control are indeed required.

E-sports are Not Sports

The conclusion of this paper will be that e-sports are not sports. I begin by offering a stipulation and a definition. I stipulate that what I have in mind, when thinking about the concept of sport, is ‘Olympic’ sport. And I define an Olympic Sport as an institutionalised, rule-governed contest of human physical skill. The justification for the stipulation lies partly in that it is uncontroversial. Whatever else people might think of as sport, no-one denies that Olympic Sport is sport. This seeks to ensure that those who might wish to dispute my conclusion might stay with the argument at least for as long as possible. Secondly, the justification for the stipulation lies partly in its normativity—I have chosen an Olympic conception of sport just because it seems to me to offer some kind of desirable version of what sport is and might become. Thirdly, I give examples which show how prominent promoters of e-sports agree with my stipulation, as evidenced by their strenuous attempts to comply with it in order to join the Olympic club. The justification for the definition lies in the conceptual analysis offered—an ‘exhibition-analysis’ which clarifies the concept of sport by offering ‘construals’ of the six first-level terms. The conclusion is that e-sports are not sports because they are inadequately ‘human’; they lack direct physicality; they fail to employ decisive whole-body control and whole-body skills, and cannot contribute to the development of the whole human; and because their patterns of creation, production, ownership and promotion place serious constraints on the emergence of the kind of stable and persisting institutions characteristic of sports governance. Competitive computer games do not qualify as sports, no matter what ‘resemblances’ may be claimed. Computer games are just that—games.

Dynamic Locomotion Through Online Nonlinear Motion Optimization for Quadrupedal Robots

This letter presents a realtime motion planning and control method that enables a quadrupedal robot to execute dynamic gaits including trot, pace, and dynamic lateral walk, as well as gaits with full flight phases such as jumping, pronking, and running trot. The proposed method also enables smooth transitions between these gaits. Our approach relies on an online zero-moment point based motion planner which continuously updates the reference motion trajectory as a function of the contact schedule and the state of the robot. The reference footholds for each leg are obtained by solving a separate optimization problem. The resulting optimized motion plans are tracked by a hierarchical whole-body controller. Our framework has been tested in simulation and on ANYmal, a fully torque-controllable quadrupedal robot, both in simulation and on the actual robot.

Linear Matrix Inequalities for Physically Consistent Inertial Parameter Identification: A Statistical Perspective on the Mass Distribution

With the increased application of model-based whole-body control in legged robots, there has been a resurgence of research interest into methods for accurate system identification. An important class of methods focuses on the inertial parameters of rigid-body systems. These parameters consist of the mass, first mass moment (related to center of mass location), and rotational inertia matrix of each link. The main contribution of this paper is to formulate physical-consistency constraints on these parameters as Linear Matrix Inequalities (LMIs). The use of these constraints in identification can accelerate convergence and increase robustness to noisy data. It is critically observed that the proposed LMIs are expressed in terms of the covariance of the mass distribution, rather than its rotational moments of inertia. With this perspective, connections to the classical problem of moments in mathematics are shown to yield new bounding-volume constraints on the mass distribution of each link. While previous work ensured physical plausibility or used convex optimization in identification, the LMIs here uniquely enable both advantages. Constraints are applied to identification of a leg for the MIT Cheetah 3 robot. Detailed properties of transmission components are identified alongside link inertias, with parameter optimization carried out to global optimality through semidefinite programming.

Dual-arm Cable Manipulation by Whole-body Control of a Humanoid Robot

Dual-arm Cable Manipulation by Whole-body Control of a Humanoid Robot

Momentum Control of an Underactuated Flying Humanoid Robot

The letter takes the first step toward the development of a control framework for underactuated flying humanoid robots. These robots may thus have the capacities of flight , contact locomotion , and manipulation , and benefit from technologies and methods developed for Whole-Body Control and Aerial Manipulation . As in the case of quadrotors, we assume that the humanoid robot is powered by four thrust forces. For convenience, these forces are placed at the robot hands and feet. The control objective is defined as the asymptotic stabilization of the robot centroidal momentum. This objective allows us to track a desired trajectory for the robot center of mass and keep small errors between a reference orientation and the robot base frame. Stability and convergence of the robot momentum are shown to be in the sense of Lyapunov. Simulations carried out on a model of the humanoid robot iCub verify the soundness of the proposed approach.

Autonomous SLAM based humanoid navigation in a cluttered environment while transporting a heavy load

Although in recent years there have been quite a few studies aimed at the navigation of robots in cluttered environments, few of these have addressed the problem of robots navigating while moving a large or heavy objects. This is especially useful when transporting loads with variable weights and shapes without having to change the robot hardware. Inspired by the wide use of makeshift carts by humans, we tackle, in this work, the problem of a humanoid robot navigating in a cluttered environment while displacing a heavy load that lies on a cart-like object. We present a complete navigation scheme, from the incremental construction of a map of the environment and the computation of collision-free trajectories to the control to execute these trajectories. Our contributions are as follows: (1) a whole-body control scheme that makes the humanoid use its hands and arms to control the motions of the cart–load system (e.g. tight turns) (2) a sensorless approach to automatically select the appropriate primitive set according to the load weight (3) a motion planning algorithm to find an obstacle-free trajectory using the appropriate primitive set and the constructed map of the environment as input (4) an efficient filtering technique to remove the cart from the field of view of the robot while improving the general performances of the SLAM algorithms and (5) a continuous and consistent odometry data formed by fusing the visual and the robot odometry information. We present experiments conducted on a real Nao robot, equipped with an RGB-D sensor mounted on its head, pushing a cart with different loads. Our experiments show that the payload can be significantly increased without changing the robot’s main hardware, and therefore enacting the capacity of humanoid robots in real-life situations.

The CoDyCo Project Achievements and Beyond: Toward Human Aware Whole-Body Controllers for Physical Human Robot Interaction

The success of robots in real-world environments is largely dependent on their ability to interact with both humans and said environment. The FP7 EU project CoDyCo focused on the latter of these two challenges by exploiting both rigid and compliant contacts dynamics in the robot control problem. Regarding the former, to properly manage interaction dynamics on the robot control side, an estimation of the human behaviors and intentions is necessary. In this letter, we present the building blocks of such a human-in-the-loop controller, and validate them in both simulation and on the iCub humanoid robot using a human–robot interaction scenario. In this scenario, a human assists the robot in standing up from being seated on a bench.

Whole-body Control of a Mobile Manipulator Using Feedback Linearization and Dual Quaternion Algebra

Essa dissertacao de mestrado apresenta o controle de corpo completo de um manipulador movel nao-holonomico utilizando controle por realimentacao entrada-saida e algebra de quaternios duais. O controlador, cuja referencia e um quaternio dual unitario representandoa pose desejada do efetuador, age como um gerador dinâmico de trajetoria para o efetuador, e os sinais de entrada tanto para a base movel nao-holonomica quanto para o braco manipulador sao gerados utilizando a pseudo-inversa da matriz Jacobiana de corpo completo.Para lidar com as restricoes de nao-holonomia, o sinal de entrada para a base movel gerado pelo controle de corpo completo e devidamente remapeado para garantir factibilidade. Restricoes nos limites das juntas, existentes na plataforma real, sao tratadas como restricoes na matriz Jacobiana. A estabilidade de Lyapunov para o para o sistema em malha fechada e apresentada, utilizando o metodo direto de Lyapunov e o teorema de Matrosov, e resultados experimentais em uma plataforma real sao realizados para comparar o esquema proposto com um controlador cinematico tradicional de corpo completo. Os resultadosmostram que, para uma taxa de convergencia similar, o controlador nao linear e capaz de gerar movimentos mais suaves, alem de possuir menor esforco de controle do que o controlador linear.

Whole-Body Control [TC Spotlight

Reports on the activities and research conducted by the IEEE Robotics and Automation Society Technical Committee on Whole-Body Control (WBC-TC) that was established in 2014.