Pascale Chiron

Kinematic and dynamic model-based control of wheeled mobile manipulators: A unified framework for reactive approaches

The work presented in this paper aims at providing a unified modelling framework for the reactive control of wheeled mobile manipulators (WMM). Where most work in the literature often provides models, sometimes simplified, of a given type of WMM, an extensive description of obtaining explicit kinematic and dynamic models of those systems is given. This modelling framework is particularly well suited for reactive control approaches, which, in the case of mobile manipulation missions, are often necessary to handle the complexity of the tasks to be fulfilled, the dynamic aspect of the extended workspace and the uncertainties on the knowledge of the environment. A flexible reactive framework is thus also provided, allowing the sequencing of operational tasks (in our case, tasks described in the end-effector frame) whose natures are different but also an on-line switching mechanism between constraints that are to be satisfied using the system redundancy. This framework has been successfully implemented in simulation and on a real robot. Some of the obtained results are presented.

On realistic human motion simulation for virtual manipulation tasks

Repetitive motion on industrial workstations is at the origin of musculoskeletal disorders (MSD). There is a need for new simulation tools that allows for human motion prediction. This paper addresses the problem of realistic human motion simulation on industrial workstations. It is based on motion analysis and control synthesis on a kinematics basis. Literature and motion captures are compared. Then, a scheme based on optimization in Cartesian and motor space is proposed and tested on 2 significant examples. Singular Value theory is used for determining the shape of hand paths. Finally, an industrial application is simulated. Simulations are realized with a 23 Degrees Of Freedom (DOF) virtual human and are also of interest for humanoid robots.

Study of drought impact on inland navigation systems based on a flow network model

Inland navigation systems are large scale networks that are used for transport. The navigation can be accommodated if the navigation condition are gathered, i.e. if there is enough volume of water in each part of the network. Thus, it is necessary to supply the inland navigation networks with water and to well dispatch the available volume of water on the whole system. This aim is generally achieved without difficulty in normal condition. However, during drought periods, the available volume of water is decreasing and the navigation conditions would not be reached everytime. These situations are expected to be more current in the future specially in a global change context in which the frequency and the magnitude of drought events will increase. Hence, it is necessary to design some tools to study the resilience of inland navigation networks against drought events. For this purpose a flow network model, allowing to simulate the inland navigation systems, is proposed in this paper.

MULTIMODELLING STEPS FOR FREE-SURFACE HYDRAULIC SYSTEMS CONTROL

The chapter presents multimodelling steps of free-surface hydraulic system for the design of control strategies. This method makes it possible to represent, simply and accurately, the non-linear hydraulic system dynamics with large operating conditions. The multimodelling steps are performed in order to lead to the determination of a finite number of models. The models are selected online by the minimization of a quadratic criterion. It is an interesting alternative to the use of Saint Venant partial differential equations because it allows the design, the tuning and the validation of control strategies.The evaluation of the proposed method is carried out by simulation within the framework of a canal with trapezoidal profile showing its effectiveness.

On geodesic paths and least-cost motions for human-like tasks

We are interested in “human-like” automatic motion generation. The apparent redundancy of the humanoid wrt its explicit tasks lead to the problem of choosing a plausible movement in the framework of redundant kinematics. Some results have been obtained in the human motion literature for reach motion that involves the position of the hands. We discuss these results and a motion generation scheme associated. When orientation is also explicitly required, very few works are available and even the methods for analysis are not defined. We discuss the choice for metrics adapted to the orientation, and also the problems encountered in defining a proper metric in both position and orientation. Motion capture and simulations are provided in both cases. The main goals of this paper are : - to provide a survey on human motion features at task level for both position and orientation, - to propose a kinematic control scheme based on these features - to define properly the error between motion capture and automatic motion simulation.

GENERATION OF POSTURE AND HUMAN MOVEMENT FOR WORKSPACE DESIGN

Abstract This paper deals with modelling of human movement in order to provide an analysis and simulation tool which could be used for workspace design. The goal of this work is to generate postures and displacements in an automatic way thanks to the state of the art on the human movement. We are interested in systematic generation of human motion and postures that correspond to working tasks defined by grasps or, more generally, by locations of particular frames linked to hands, head or another body of interest. These tasks are reaching — point to point — tasks or tasks with imposed cartesian path. So the problem is: how to control global posture when frames attached to some bodies are imposed? For that, kinematic models resulting from robotics are used and a redundancy resolution scheme is proposed that makes possible to take into account the articular limits.

MODELLING, RESOURCE ALLOCATION AND SETPOINTS ASSIGNMENT OF COMPLEX HYDROGRAPHIC SYSTEMS

Abstract A new strategy based on a supervision and hybrid control accommodation is proposed to improve the water asset management of complex hydraulic systems. This strategy requires the definition of rules to achieve a generic resource allocation and setpoint assignment. A modelling method of the complex hydrographic network based on a weighted digraph of instrumented points, is also presented. The simulation results of the strategy applied to a hydrographic system composed of one confluent and one difluent show its efficiency and its effectiveness.

HYBRID CONTROL ACCOMMODATION FOR WATER-ASSET MANAGEMENT OF HYDRAULIC SYSTEMS SUBJECTED TO LARGE OPERATING CONDITIONS

Abstract The Hybrid Control Accommodation (HCA) strategy was proposed to improve the water asset management of hydraulic systems by resource allocation and setpoint assignment. Hydraulic system dynamics are taking into account during the setpoint assignment step which consists in controlling gates for larges operating conditions. For hydraulic systems subjected to strong disturbances, transfer delays are variable, thus different operating modes must be considered. A multimodelling method associated with a transfer delay selection technique allowing for the determination of the number of models, is proposed. The simulation results on the first reach of the Neste canal show the effectiveness of the HCA strategy.

Hybrid Control Accommodation by Resource Allocation and Setpoint Assignment 1

Abstract This paper presents a supervision and hybrid control accommodation method applied to water management. The supervision module allows the process data conditioning, the detection of discrepancy between the expected value and the real value, and the process state diagnosis. In the hybrid accommodation module, setpoints are determined taking into account the detected discrepancy, process state, time delays and communication protocol. The hybrid control method was developed to carry out the water management of a reach canal.

Transportation network model with time delay for flood lamination strategy

Flooding due to rivers overflowing have affected this year many countries in the world. The engendered problems, due to their intensity, are relative to goods and persons safety, and often cause a sharp increase of the insurance costs, which is no more tolerable in the actual economic context. To prevent these problems, it is necessary to limit water heights downstream the streams. In the literature, numerous described works were done on flows modelling and management. The work presented in this paper, is interested in the quantitative management by means of floods diversion areas placed along the river and for which location and sizing are known. A management method computing the height of gates opening at each time step is proposed. The strategy is based on a transportation network model of the flood diversion area system including the time transfer delays. It allows the computation of the water volumes to be stored in time. Simulation results for different flood episode are discussed.