Publications by Philippe Müllhaupt

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The goal of the present work was assess the feasibility of using a pseudo-inverse and null-space optimization approach in the modeling of the shoulder biomechanics. The method was applied to a simplified musculoskeletal shoulder model. The mechanical syste ...

Predictive Control of Unstable Nonminimum-phase Systems K. Guemghar, B. Srinivasan, Ph. Mullhaupt, D. Bonvin ´ Institut d’Automatique, Ecole Polytechnique F´d´rale de Lausanne, ee CH-1015 Lausanne, Switzerland. Predictive control is a very eﬀective approach for tackling problems with constraints and nonlinear dynamics, especially when the analytical computation of the control law is diﬃcult. Standard predictive control involves predicting the system behavior over a prediction horizon and calculating the inp

We present a new walking foot-placement controller based on 3LP, a 3D model of bipedal walking that is composed of three pendulums to simulate falling, swing and torso dynamics. Taking advantage of linear equations and closed-form solutions of the 3LP mode ...

A vast majority of the available biomechanical models of the human shoulder has been developed based on inverse dynamics, e.g. [1,2]. This imposes a number of limitations on their application. For instance, the glenohumeral joint is approximated as an idea ...

Estimation of muscle forces in over-actuated musculoskeletal models involves optimal distributions of net joint moments among muscles by a standard load-sharing scheme (SLS). Given that co-contractions of antagonistic muscles are counterproductive in the n ...

Reaction systems are typically represented by first-principles models that describe the evolution of the states (typically concentrations, volume and temperature) by means of conservation equations of differential nature and constitutive equations of algeb ...

A numerical sufficiency test for the asymptotic stability of linear time-varying Hurwitz systems is proposed. The algorithmic procedure constructs a bounding tube in which the state is guaranteed to stay. The continuous-time system is evaluated at discrete ...

Improvement over classical dynamic feedback linearization for a unicycle mobile robots is proposed. Compared to classical extension, the technique uses a higher-dimensional state extension, which allows rejecting a constant disturbance on the robot rotatio ...

This paper proposes a feedback law capable of swinging up and stabilizing the cartpendulum system. The approach uses an iterative algorithm that is typically used to construct a locally linearizing output for nonlinear control-affine systems. However, rath ...

Two Lie algebroids are presented that are linked to the construction of the linearizing output of an affine in the input nonlinear system.\ The algorithmic construction of the linearizing output proceeds inductively, and each stage has two structures, name ...

The control of the current, position and shape of an elongated cross-section tokamak plasma is complicated by the so-called instability of the current vertical position. Linearized models all share the feature of a single unstable eigenmode, attributable t ...

This paper extends the quotient method proposed in [1] and applies it to stabilize a “ball-on-a-wheel” system. The quotient method requires a diffeomorphism to obtain the normal form of the input vector field and uses canonical pro- jection to obtain the q ...

Nonlinear modeling of coaxial microhelicopters is studied. All equations are derived using a Lagrangian approach and simplified aerodynamics assumptions so that all parameters have a physical meaning; there is no “black box.” The model is constructed with a view toward control design and real-time simulation. The state-space size is kept minimal, and the numerical conditioning of the resulting differential equations is critical. A set of coordinate transformations is proposed that allows averaging and reduc

A modeling framework is proposed for the control of rigid and flexible cable-like systems such as cranes, together with a systematic algorithm for computing flat outputs of mechanical systems for which the flat output is a linear combi- nation of free coor ...

Nano-positioning devices constitute the mechatronic heart of the VLTI (Very Large Telescope Interferometer) for the ESO (European Southern Observatory) astrometry instrumentation. In the context of the development of a new optical Differential Delay Line ( ...

The loss of feedback linearizability of control systems is studied when restricted to a submanifold of the state-space. The slow approximation of singularly perturbed systems also falls into this category. We show that even if the static-feedback linearizability is lost, the flatness property of the system may be conserved. The comparison between a flexibly linked pendulum and a rigidly linked one, both equipped with two controls and evolving in the plane, illustrates the theoretical results.

A new dynamical model of the shoulder has been developed. It consists of eleven muscles. The glenohumeral joint, modeled as a spherical joint, allows three rotations and blocks the translations. Muscle wrapping around a spherical humeral head is calculated ...

This paper considers a helicopter-like setup called the Toycopter. Its particularities reside first in the fact that the toycopter motion is constrained to remain on a sphere and second in the use of a variable rotational speed of the propellers to vary th ...

An algorithmic method is proposed to design stabilizing control laws for a class of nonlinear systems that comprises single-input feedback-linearizable systems and a particular set of single-input non feedback-linearizable systems. The method proceeds iter ...

A double-stage feedback control structure for a double-stage mechanical system, with a single optical metrology is developed to reach the nanometer accuracy at high bandwidth over large displacements. A piezoelectric stack actuator is used for fine positio ...

Philippe Müllhaupt

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A musculoskeletal shoulder model based on pseudo-inverse and null-space optimization

Predictive Control of Fast Unstable and Nonminimum-phase Nonlinear Systems

Imprecise dynamic walking with time-projection control

A framework for forward-dynamics simulation of the human shoulder

Muscle co-contraction in an upper limb musculoskeletal model: EMG-assisted vs. standard load-sharing

Minimal State Representation for Open Fluid-Fluid Reaction Systems

A Numerical Sufficiency Test for the Asymptotic Stability of Linear Time-Varying Systems

Velocity-Scheduling Control for a Unicycle Mobile Robot: Theory and Experiments

Stabilization of the cart-pendulum system through approximate manifold decomposition

On two isomorphic Lie algebroids for Feedback Linearization

Improving tokamak vertical position control in the presence of power supply voltage saturation

Quotient method for stabilising a ball-on-a-wheel system – Experimental results

Nonlinear Analysis of a Coaxial Microhelicopter with a Bell Stabilizer Bar

Modeling and Flatness of Rigid and Flexible Cable Suspended Underactuated Robots

Trajectory Tracking through Overactuation for an Optical Delay Line

Feedback Linearizability and Flatness in Restricted Control Systems

Dynamical biomechanical model of the shoulder: null space based optimization of the overactuated system

Control of the Toycopter using a Flat Approximation

A quotient method for designing nonlinear controllers

Strategy for the Control of a Dual-stage Nano-positioning System with a Single Metrology