Bipédie | EPFL Graph Search

vignette|Une autruche d'Afrique, l'un des animaux bipèdes les plus rapides. La bipédie est un mode de par lequel un animal se meut sur ses deux membres postérieurs. Une espèce est dite bipède si la bipédie est son mode de locomotion ordinaire quand l'animal marche ou court. Les espèces bipèdes se rencontrent essentiellement dans deux clades de tétrapodes, les théropodes (dont les seuls représentants actuels sont les oiseaux) et les hominines (dont le seul représentant actuel est l'Homme moderne). Parmi les autres groupes, la bipédie n'est qu'intermittente ou approximative. Chez les mammifères Chez les humains Bipédie humaine La bipédie exclusive est une caractéristique dHomo sapiens et d'autres Hominina fossiles, qui se traduit par de nombreuses adaptations du squelette par rapport à celui des autres primates. Plus généralement, différentes formes de bipédie, usuelle ou intermittente, caractérisent la lignée humaine depuis sa séparation de celle des chimpanz

Foot-Interfaces Control and Human-Robot Interaction in Four-Handed Manipulation

Jacob Hernandez Sanchez

Humans have a great capacity to perform complex manipulations. However, there are many tasks for which two hands are not enough, such as in surgery. For such tasks, a dyad of people is required. However, when not used to work together, a dyad collaboration can be intermittent, slow and prone to misunderstandings if relied solely on verbal cues. The current PhD thesis report concerns the design and control of foot interfaces to enable solo four-handed manipulations. In the first part, we present the platform design in five DoF, with position mapping and haptic force feedback. We tackle the known issue of fatigue when using position mapping, by partially compensating for the dynamics of the leg. Finally, we perform a series of feasibility validations on bipedal teleoperation in 3 and 4 and 5 DoF. In the second part, a behavioural study investigates a symmetric bipedal holding and transport of an object while working on it with the hands. This study sheds light to the human capacity to use the redundancy given by augmentation with the feet, to assist the task of the hands. We investigate the effect of shared-control for lower limb teleoperation. Two modalities are used: 1. synergistic control of two robotic arms with one foot, 2. force assistance. We evaluate these strategies in terms of objective and subjective metrics, such as physical and cognitive workload and fluency.Aiming at enabling individualized foot dexterous control, in the third part of the thesis, we addressed the problem of bio-mechanical coupling of foot rotations. This is done by detecting intention to grasp, and selectively easing this action while haptically constraining the foot gestures for tool alignment. A user study was conducted to evaluate our proposed approach in a surgical laparoscopic gripper.In the fourth and final part, we focus on investigating more demanding tasks for the feet, as well as the coordinated control of four hands, during hybrid-robotic laparoscopic surgery. One foot controls a camera, while the other one performs a grasping task. Noteworthy is that all four-arms can be controlled simultaneously. For easing the solo surgical task, we design haptic assistance, for autonomous grasping operated by the foot. Finally, we perform a systematic behavioural study to understand the effect of our haptic-shared-control, along with an assistance modality for camera tool-tracking. We cover uni-pedal, bipedal and four-handed task scenarios. Our main conclusion is that foot gestures can be conditioned with haptic feedback, to effectively control multiple degrees of freedom of a supernumerary robotic arm. Thereby enabling four-arm simultaneous manipulations. This is done specifically by leveraging 1. a foot kinesthetic haptic platform that allows for the use of two feet, 2. leg compensation, and virtual assistive impedance, which are useful to increase comfort and alleviate fatigue. 3. Hybridization of control mappings for foot gestures, with limited range of motion and oblique axes of rotation, 4. Haptic shared-control strategies for prehensile force assistance, coordination assistance, and DoF-individuation assistance. We found that robotic assistance is highly appreciated, and has an important role in simplifying four-handed tasks. Indeed, these are instrumental considerations to enable a more fluent, less demanding, and more performant interaction, in tasks where the feet are supplementing the task of hands.

EPFL2022

Rich and Robust Bio-Inspired Locomotion Control for Humanoid Robots

Nicolas Benoît Dominique Van der Noot

Bipedal locomotion is a challenging task in the sense that it requires to maintain dynamic balance while steering the gait in potentially complex environments. Yet, humans usually manage to move without any apparent difficulty, even on rough terrains. This requires a complex control scheme which is far from being understood. In this thesis, we take inspiration from the impressive human walking capabilities to design neuromuscular controllers for humanoid robots. More precisely, we control the robot motors to reproduce the action of virtual muscles commanded by stimulations (i.e. neural signals), similarly to what is done during human locomotion. Because the human neural circuitry commanding these muscles is not completely known, we make hypotheses about this control scheme to simplify it and progressively refine the corresponding rules. This thesis thus aims at developing new walking algorithms for humanoid robots in order to obtain fast, human-like and energetically efficient gaits. In particular, gait robustness and richness are two key aspects of this work. In other words, the gaits developed in the thesis can be steered by an external operator, while being resistant to external perturbations. This is mainly tested during blind walking experiments on COMAN, a 95 cm tall humanoid robot. Yet, the proposed controllers can be adapted to other humanoid robots. In the beginning of this thesis, we adapt and port an existing reflex-based neuromuscular model to the real COMAN platform. When tested in a 2D simulation environment, this model was capable of reproducing stable human-like locomotion. By porting it to real hardware, we show that these neuromuscular controllers are viable solutions to develop new controllers for robotics locomotion. Starting from this reflex-based model, we progressively iterate and transform the stimulation rules to add new features. In particular, gait modulation is obtained with the inclusion of a central pattern generator (CPG), a neural circuit capable of producing rhythmic patterns of neural activity without receiving rhythmic inputs. Using this CPG, the 2D walker controllers are incremented to generate gaits across a range of forward speeds close to the normal human one. By using a similar control method, we also obtain 2D running gaits whose speed can be controlled by a human operator. The walking controllers are later extended to 3D scenarios (i.e. no motion constraint) with the capability to adapt both the forward speed and the heading direction (including steering curvature). In parallel, we also develop a method to automatically learn stimulation networks for a given task and we study how flexible feet affect the gait in terms of robustness and energy efficiency. In sum, we develop neuromuscular controllers generating human-like gaits with steering capabilities. These controllers recruit three main components: (i) virtual muscles generating torque references at the joint level, (ii) neural signals commanding these muscles with reflexes and CPG signals, and (iii) higher level commands controlling speed and heading. Interestingly, these developments target humanoid robots locomotion but can also be used to better understand human locomotion. In particular, the recruitment of a CPG during human locomotion is still a matter open to debate. This question can thus benefit from the experiments performed in this thesis.

EPFL2017