Despite exoskeletons becoming widespread tools in industrial applications, the impact of the design of human–exoskeleton physical interfaces has received little attention. This study aims at thoroughly quantifying the influence of different physical human–exoskeleton interfaces on subjective and objective biomechanical parameters. To this aim, 18 participants performed elbow flexion/extension movements while wearing an active exoskeleton with three different physical interfaces: a strap without any degree of freedom, a thermoformed orthosis with one (translation) and three degrees of freedom (translation and rotations). Interaction efforts, kinematic parameters, electromyographic activities, and subjective feelings were collected and examined during the experiment. Results showed that increasing the interaction area is necessary to improve the interaction quality at a subjective level. The addition of passive degrees of freedom allows significant improvements on both subjective and objective measurements. Outcomes of this study may provide fundamental insights to select physical interfaces when designing future exoskeletons.

The work presented here focuses on humanoid gait generation. More precisely we deliberately separate the motion generation in two distinct parts: the coordination and the stability. The goal is to highlight the human coordination, and then reduce its complexity to a minimal set of relations (twelve gait descriptors with respect to an unique gait parameter). Polynomial approximations of these relations are done and implemented into a kinematic simulation of an anthropomorphic humanoid model coming from a real humanoid robot. This simulation allows the leg coordination through the contact with the environment. After the validation of the coordination relations, they are injected into an actual humanoid robot NAO. We choose the small humanoid NAO from Aldebaran society because its size and set up permit to keep the gait coordination (in three dimensions) part primarily in gait generation by comparison with the stability part (in the frontal plane). The results are promising and authorize to plan an application of this work on a more complex humanoid, plus the study of other gaits, and more important on the gait transition.

This paper proposes an energy control method for the dynamic walking of a planar biped, allowing obstacle crossing. This approach was tested in simulation on a numerical model of the Hydroïd robot of the Laboratoire d'Ingénierie des Systèmes de Versailles, and achieved a dynamic walking with a 1.3 m/s maximum speed and the crossing of an obstacle thanks to inertia forces, by leaning with the front foot on the obstacle. The propulsion energy of the system is produced by the rear leg, endowed with four actuated degrees-of-freedom (hip, knee, ankle, toes), and controlled by a force control using four degrees-of-freedom in the non singular case, and three degrees-of-freedom in the singular case.

This paper deals with a research work aimed to develop a new three degrees of freedom (DOF) mechanism for humanoid robots. The main idea is to build hybrid (3DOF) mechanism, which avoids the drawbacks of the serial and parallel mechanisms. The new solution has to merge the advantages of both classical (serial and parallel) structures in order to achieve optimal performances. The proposed mechanism can be used as a solution for several modules in humanoid robot. The hip mechanism is taken as an example to illustrate the contribution of this paper. To evaluate the performances of the system, simulation of this new mechanism is carried out with Adams software. Geometrical and Kinematic models are developed and included in the simulation tool. Based on biomechanical data, analysis of the new kinematic structure is carried out. The design of the proposed solution is then described. Finally the first prototype developed for the HYDROi¿D robot's hip is presented. This mechanism is a part of an International patent accepted at INPI- France.

This paper presents an approach to control gaits of humanoid bipedal robots in operational space without reference trajectories. This control strategy is based on the planning of the sequential events during the walking process. The aim of this study is to propose a new control strategy which is more reactive, permits a precise coordination of both legs during the double stance phase and the generation of dynamic 3D walking of an anthropomorphic biped with flexible feet. Based on homogeneous transformation matrices, the control strategy integrates three aspects in one unified representation: structural parameters of the robot, measurements given by sensors, planning of the sequential events during the different stages of the walk.

This paper presents a new approach to control gaits of humanoid bipedal robots in the operational space. This strategy based on the homogeneous transformation matrices integrates, in a unified representation, the structural aspects of the robot, the reference trajectories based on motion capture, the measures given by the robot sensors, the locomotion constraints and the high-level control using desired trajectories modified at each sample time. This approach is applied on a biped with flexible feet walking with an average speed equal to 1.2 m/s.

This paper presents a tool called sequential method of analytical potentials aiming to generate dynamic gaits for biped robots. The objective is to control the different accelerations governing the evolution of the robot by modifying precisely and directly its own dynamic effects. Taking into account the intrinsic dynamics of the robot as well as the capability of its joint actuators, this method is based on the use of the dynamic propulsion potential and is illustrated on the biped robot RABBIT.

This paper deals with a novel approach based on the synergy between the dynamic motions of balancing masses and arms to reject large perturbations applied to the upper part of a bipedal robot. Initially the stabilization is carried out with a trunk having 4 degrees of freedom: three translations and one rotation. In the second time the stabilization is performed with a system with arms and having 10 DOFs. At first, for a vertical posture of the robot, the trunk bodies of ROBIAN are used to compensate the external three-dimensional efforts applied to the robot. During the simulation, this study allows us to determine on-line, the required movements and accelerations of the trunk bodies in order to maintain the robot stability. In the following stage, we study the required movements of a system which is made up of a trunk and two arms in order to ensure the robot stability in presence of disturbances or during a handling of an object. The same formalism is chosen to study the dynamics of the new upper part of the robot. This study shows the importance of the arms for the robot stability.

This paper presents an analytical approach for the generation of walking gaits with a high dynamic behaviour. The principle is to modify the dynamic effects generated by the robot directly by taking into account the intrinsic dynamics of the robot as well as the capability of its joint torques. In order to perform this, two criterions based on dynamics are proposed: the "dynamic propulsion criterion" and the "dynamic propulsion potential". This general approach is illustrated for an underactuated robot without foot, which can not be statically stable

This paper presents the first theoretical tools to control an under-actuated robot by taking into account its intrinsic dynamics. In order to perform this control, the idea is to modify the configuration and the dynamic effects of the robot if the measured velocity of the robot is not the desired one

In this paper, we propose an experimental validation of a new control strategy based on the use of intuitive control and neural networks CMAC in order to control the under-actuated robot RABBIT. The training of the neural networks is carried out during the simulation. When the training is finished, these neural networks are used to control the real robot. We also present an evaluation of the robustness of this control strategy.

In this paper, we propose a control strategy allowing us to perform the transition of velocities included in [0 m/s; 1 m/s] for the dynamic walking of an under-actuated robot (RABBIT) without reference trajectories. This strategy of control also enables us to carry out the transition from stop towards walking and the reverse process. The interest of this method resides in the fact that on one hand the intrinsic dynamics of the system are exploited by using a succession of active and passive phases and on the other hand that the control strategy is very easy to implement on-line.

In this paper we address the issue of controlling the stability of legged robots based on the virtual generalized stabilizer (VGS) introduced in [J. Foret, et al.,2002]. The proposed approach is a theoretical framework that gives a unified point of view to design and to control the walking gaits. Although the presented work is general, the application focuses on the particular problem of static stability maintenance of a biped robot subject to a destabilizing impulsive force applied on its trunk.

The objective of the work is to evaluate the contribution of flexibilities in the feet of a bipedal robot during a dynamic walk. The two major effects are the diminution of the intensity of the normal force when the heel touches the ground and the increase of the phase of double support allowing a better stability of the system. Another notable effect is the analogy between the passive flexion amplitude of the tiptoes and the measured results of human subjects.

This paper deals with an approach to carry out the transitions of a walking robot. A set of elementary transformations is proposed to modify the locomotion parameters allowing one to obtain various kinds of walks. Some simulation results are given.

This paper deals with an approach to carry out the dynamic walk of anthropomorphic bipeds. At first, the way to reproduce a reference walking cycle for a standard biped is proposed. Secondly, the foot/ground interaction model is exposed. A set of elementary transformations is then described to modify the locomotion parameters allowing us to obtain various walking gaits for bipeds having different sizes and weights. Some simulation results are finally given.