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This paper describes a developed verticalisation function integrated into a mobile transportation platform. The system is known as Gyrolift, a type of mobility-aided wheelchair based on a two-wheel auto-balanced personal transporter (PT). The system is equipped with a robotic module designed for helping users reach a standing position from a seated one. It also allows them to safely keep the standing posture to interact with the environment and have access to objects at a high level. The main contribution of this work resides in the design of verticalisation solution that ensures both the trajectory adapted to the user while respecting the constraint of the mobile platform. This solution is designed to not only keep the user in a standing posture but also to prevent instability of the PT. In order to justificate its feasibility, the proposed device as human-aid was evaluated in a series of simulations. Experimental tests were also conducted.

This article describes the use of a robotic platform in the analysis of the posture. This platform is able to move while providing the position of the center of pressure (COP). Therefore, biomechanical data are calculated using the measurements provided by the sensors associated to the platform. These allow the estimation of joints stabilometric signals from the data and loads measured between the user and the platform. In our analysis, several levels of disturbance were tested to determine the level and type of disturbance compatible with the strategy adopted by the user. The experiments conducted have confirmed the usefulness of such platform in supporting therapists in their analysis. The features of the used platform enable the simulation of dynamic movements in transportation and it allows an omnidirectional movement on four axles. It is capable of supporting the weight of a human of about 120kg while applying maximum acceleration of \(2m/s^2\) along longitudinal or lateral directions. Some results on the design of the platform and the analysis will be exposed in this article.

In this article we develop a new approach to control an omnidirectional mobile manipulator. This approach is based on a kinematic command structure and impedance control technique. First we define multiple control behaviors depending on the robot tasks. Two behaviors are considered here the synchronized one and the independent one. Each behavior mentioned above is described in terms of force and position models in order to allow each robot to regulate his corresponding behavior. In the case of synchronized situation, kinematic modelling is presented with particular emphasis on redundancy. We use the additional task concept to solve the control problem of these redundant holonomic systems by taking into account the external forces.

International audience; In this article we develop a new approach to control an omnidirectional mobile manipulator. The robot is considered as an individual agent aimed to perform robotic tasks described in terms of displacement and force interaction with the environment. A reactive architecture and impedance control are used to ensure reliable task execution in response to environment stimuli. The mechanical structure of our holonomic mobile manipulator is built from two joint manipulator mounted on an holonomic vehicle. The vehicle is equipped using three motorized axles with two spherical orthogonal wheels. The dynamics of the mobile manipulator robot is defined tacking into account the dynamical interaction between the base and the manipulator. Then we design a nonlinear controller for the robot using input-state linearization method. The control structure of the robot is built in order to demonstrate the main capabilities in navigation and obstacle avoidance. Several simulations were conducted to prove the effectiveness of our concept.

International audience; In this article we develop a new approach to control an omnidirectional mobile manipulator. This approach is based on a layered command structure and impedance control technique. First we define multiple control behaviors depending on the robot tasks. Two behaviors are considered here the synchronized one and the independent one. Each behavior mentioned above is described in terms of force and position models in order to allow each robot to regulate his corresponding behavior. In the case of synchronized situation, kinematic modeling is presented with particular emphasis on redundancy. We use the additional task concept to solve the control problem of these redundant holonomic systems by taking into account the external forces.

International audience; In this paper, we give sufficient conditions for the stability of a class of switched systems. Based on the symmetric part of the state space matrix and on the LaSalle's invariance principle, to ensure the asymptotic stability of switched linear systems, under a special class of switching signals. The proposed stability results are used to design observer of switched linear systems for which the discrete state is available. Examples are given to highlight our propositions.

International audience; In this paper, we focus on one of the central problem of observers design and control of general manipulation systems. The tasks performed by manipulators involve physical interaction with their environment. This naturally gives rise to interactive forces between each manipulator and the object. The mechanical compliance introduced by the cooperation between the manipulators and their interactions with load is complex. First, the control must be designed in this case in order to realize the object trajectory and/or external forces tracking. But, the controller action must respect and not violate at each moment the kinematic constraint of the manipulation system. Seconde and more importantly, the augmented manipulation system (the closed chain : manipulators-object) is nonlinear and complex system, then the observer design is very difficult, which motivate us to develop a new approach to design a multi models-based observer which we call hysteresis hybrid observer.

International audience; This brief addresses the problem of controlling the planar position and orientation of an autonomous underactuated surface vessel. Under realistic assumptions, we show, first, that there exists a natural change of coordinates that transforms the whole dynamical system into a cascade nonlinear system, and, second, the control problem of the resulting system can be reduced to the stabilization of a third-order chained form. A time-invariant discontinuous feedback law is derived to guarantee global uniform asymptotic stabilization of the system to the desired configuration. The construction of such a controller is based on the backstepping design approach. A simulation example is included to demonstrate the effectiveness of the suggested approach

International audience; This paper is devoted to the problem of design a dynamic controller of switched linear systems. In the first part of this paper, we give some remarks about the influences of switching signal on the asymptotic stability of switched systems. We give a practical example to generate a large class of switching signals. The second part is devoted to the switched dynamic controller design, based on a common Lyapunov function approach. A sufficient condition is formulated as an LMI problem for the switched controller design under arbitrary switching. A stabilizing switched controller with regional pole placements is also formulated as a convex problem, an LMI approach is used to derive the switched dynamic controller with performance limitations

International audience; In this paper, we deal with the observability of piecewise-affine hybrid systems. Our aim is to give sufficient conditions to observe the discrete and continuous states, in terms of algebraic and geometrical conditions. Firstly, we will give the algebraic conditions to observe the discrete state based on the switch function reconstruction for linear hybrid systems. Secondly, we will give a geometrical condition based on the transversality concept for nonlinear hybrid systems. Throughout this paper, we illustrate our propositions with examples and simulations.