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HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

International audienceIn this paper, we propose a novel reference model-based control approach for automotive longitudinal control. The reference model is nonlinear and provides dynamic solutions consistent with safety constraints and comfort specifications. The model is based on physical laws of compliant contact and has the particularity that its solutions can be explicitly described by integral curves. This allows to characterize the set of initial condition for which the constraints can be met. This model is combined with a simple feedback loop used to compensate unmodeled dynamics and external disturbances. Model simulations together with experimental results are also presented

International audienceIn this article we first review properties of the LuGre model, including zero-slip displacement, invariance, and passivity. An extension to include velocity-dependent microdamping is also discussed. The resulting model is then used to analyze stick-slip motion. The analysis shows that stick-slip motion modeled by the LuGre model is a stiff system with different behavior in the stick and slip modes as well as dramatic transitions between these modes. The dependence of limit cycles on parameters is discussed along with the notion of rate dependence

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This paper deals with cooperative control design for nonlinear multi-agent systems. The control objective is to ensure that a group of agents reaches a formation characterized by external time-varying parameters. Firstly, a translation control design is presented to stabilize the multi-agent system to a circular motion tracking a time-varying center. Then, we propose a new framework based on affine transformations to extend previous results to more complex time-varying formations. Moreover, both control laws are improved adding a cooperative term to distribute the agents uniformly along the formation.

This paper illustrates the application of a model-based friction compensation scheme to an industrial six degrees of freedom Schilling Titan I1 hydraulic manipulator. The dynamic friction model and the control structure studied in [2] are used as a basis for this work. First, a low level nonlinear torque controller is developed to provide a high bandwidth and performance torque rt+ sponse of the hydraulic actuators. This inner loop controller is based on a nonlinear model of the servovalve and the hydraulic actuator. Friction compensation is then d e veloped. An off line identification method for the estimation of the different friction model parameters is proposed. Then an adaptative friction compensation compensation presented in [3] is applied on the hydraulic manipulator, assuming that the nominal identified model is suitably structured. Both the torque control capabilities and the friction compensation efficiency are largely illustrated through experimental results.

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