The external Cayley transform is used for the conversion between the linear dynamical systems in scattering form and in impedance form. We use this transform to define a class of formal impedance conservative boundary control systems (colligations), without assuming a priori that the associated Cauchy problems are solvable. We give sufficient and necessary conditions when impedance conservative...

The dynamics of a Spring Loaded Inverted Pendulum (SLIP) \template” [1] approximate well the center of mass (COM) of running animals, humans, and of the robot RHex [2]. Running control can therefore be ierarchically structured as a high level SLIP control and the anchoring of SLIP in the complex morphology of the physical system. Analysis of the sagittal plane lossless SLIP model has shown that...

Force control implemented by a passive mechanical device (perhaps a wrist) has inherent advantages over active implementations. A passive mechanical device can regain some of the versatility of its active counterpart if it incorporates mechanical elements with programmable parameters, e.g. damping coefficients or spring stiffnesses. We wish to characterize the range of accommodation matrices th...

L’interazione in maniera sicura e compliante è una caratteristica sempre più richiesta per i sistemi robotici. La modellazione di sistemi eseguita tramite l’uso dei sistemi port-Hamiltoninani permette di comprendere cosa avviene a livello energetico durante l’interazione e aiuta nella progettazinoe di un controllore tale che il comportamento del sistema controllato sia passivo e sicuro durante ...

The problem of the control of cooperative manipulators with passive joints and rigidly connected to a solid object is addressed in this paper. Passive joints can appear due to free-swinging joint failures or can be an intrinsic characteristic of the robots. A hybrid control of motion and squeeze force is proposed. For this purpose, a Jacobian matrix relating velocities in the actuated joints an...

In this paper we consider the synthesis of optimal feedback controllers for a stochastically-excited passive electromechanical network, subject to the constraint that in stationarity, the feedback law must be realizable with a regenerative actuation system. Regenerative systems are similar to passive systems but their dynamic constraints are more relaxed, in the sense that they only need to con...

At transitional Reynolds numbers, the laminar boundary layer separation and possible reattachment on a smooth airfoil, or wing section, are notoriously sensitive to small variations in geometry or in the fluid environment. We report here on the results of a pilot study that adds to this list of sensitivities. The presence of small holes in the suction surface of an Eppler 387 wing has a transfo...

Robot force control implemented by means of passive mechanical devices has inherent advantages over active implementations with regard to stability, response rapidity, and physical robustness. The class of devices considered in this paper consists of a Stewart platform-type mechanism interconnected with a network of adjustable mechanical elements such as springs and dampers. The control law rep...

Two concepts are advocated for the task specification and control of mechanical manipulators: 1) coding tasks in terms of velocity fields; 2) designing controllers so that the manipulator when under feedback control, interacts in an energetically passive manner with its physical environment. Based on these two concepts, a new passive velocity field controller (PVFC) is proposed which mimics the...