Paul Fisette

• PhD
• Professor (Full) at Catholic University of Louvain

The behavior of the highly dynamic mechanical transmission between the key and the strings of pianos remains insufficiently understood. Called action, this mechanism is essential for the instrument playability and touch. Upright and grand piano actions, although based on similar principles, present quite different behaviors. This work outlines two...

A piano key prototype actuated by a custom-made linear actuator is proposed to enhance the touch of digital pianos by reproducing the force feedback of an acoustic piano action. This paper presents the design and the validation of the haptic device. The approach exploits a multibody model to compute the action dynamics and the corresponding force o...

Piano actions are striking mechanisms whose functioning is based on dynamic principles. Producing a sound on a struck keyboard instrument by pressing a key slowly is impossible because the hammer needs momentum to hit the strings. For this reason, many modern studies on the piano take advantage of engineering tools in order to measure the exact beh...

We present a multibody simulator being used for compliant humanoid robot modelling and report our reasoning for choosing the settings of the simulator’s key features. First, we provide a study on how the numerical integration speed and accuracy depend on the coordinate representation of the multibody system. This choice is particularly critical for...

We present a benchmark to experimentally validate the method we have developed to simulate mechanical devices interacting with granular media. Consequently the method we develop is able to solve problems involving bilateral and unilateral constraints. The mechanical device is modelled with the multibody system approach and is described by the use o...

Ancient musical instruments can tell us much about the way composers of the past centuries wrote their music. Indeed, the sound and playing characteristics of historical instruments are often very different from those of the instruments we are used to. For example, in the case of the Viennese piano actions used by Mozart and his contemporaries, the...

Piano actions are striking mechanisms whose functioning is based on dynamic principles; producing a sound on a struck keyboard instrument by pressing a key slowly is impossible because the hammer needs momentum to hit the strings. This is also the reason why mechanisms intended for struck keyboard instruments are difficult to study; their normal fu...

Multibody dynamics simulation is widely used for testing and prototyping controllers. However, the transfer of controllers initially developed in simulation to real mechatronics platforms, requires modifications of the code in order to interface with sensors and actuators. Because of this coupling with the hardware, the controller re-usability is s...

In this paper, we discuss some very important features for getting exploitable simulation results for multibody systems, relying on the example of a humanoid robot. First, we provide a comparison of simulation speed and accuracy for kinematics modeling relying on relative vs. absolute coordinates. This choice is particularly critical for mechanisms...

Objectives This workshop aims at bringing together the researchers in robotics and related areas to share and discuss the recent novel tools and technologies in the area of simulation software. Simulation tools play a significant role in design and development of complex robotics systems. Emergent areas in the field of robotics such as design and d...

The computational efficiency of symbolic generation was at the root of the emergence of symbolic multibody programs in the eighties. At present, it remains an attractive feature of it since the exponential increase in modern computer performances naturally provides the opportunity to investigate larger systems and more sophisticated models for whic...

The present contribution focuses on the feasibility and interest of setting up a multi-disciplinary project in the field of multibody dynamics, as a sequel to the undergraduate course in classical mechanics. The pedagogical objectives of this “learning layer” cover various aspects, namely: give the student the opportunity to exploit and analyze the...

The sit to stand (STS) analysis and particularly the 5-repetition sit-to-stand test (FRSTST) introduced by Bohannon are widely used measurements of functional strength and disability level of young and elderly subjects. Usually, the functional strength and the disability level during STS are evaluated by calculating the total forces of hip and knee...

In idiopathic scoliotic patients, dynamical intervertebral efforts acting between vertebrae seem to be correlated with the spinal deformity. The quantification of these efforts, which is useful for the orthopedic surgeons to set up their surgical planning is the final objective of the present research. As a first step, we focus in this contribution...

Introduction: The internal efforts in the human body in motion could provide valuable information for the evaluation and follow-up of subjects with musculo-skeletal pathologies, such as scoliosis, but are still difficult to accurately measure. In this context, the objective of this study is to compare the lombo-sacral (L5-S1) joint efforts during g...

The goal of the present article is to analyse the performances of a modern vehicle equipped with a novel suspension system linking front, rear, right and left cylinders via a semi-active hydraulic circuit, developed by the Tenneco Automotive company. In addition to improving the vehicle's vertical performances (in terms of comfort), both the stiff...

Today, the accurate assessment of muscle forces performed by the human body in motion is still expected for many clinical applications and studies. However, as most of the joints are overactuated by several muscles, any non-invasive muscle force quantification needs to solve a redundancy problem. Consequently, the aim of this study is to propose a...

This paper presents a novel approach to optimize the design of planar mechanisms with revolute joints for function generation or path synthesis. The proposed method is based on the use of an extensible-link mechanism model whose strain energy is minimized to find the optimal rigid design. This enables us to get rid of assembly constraints and the u...

This paper deals with the optimal dimensional design of Delta robot. The aim is to obtain a manipulator with maximum dexterity and minimum projected area of the occupied volume on the base plane. Two different optimization strategies, which cope with assembly difficulties, have been applied to solve this problem. Comparing optimized Delta robot wit...

The purpose of the present research relates to the sensitivity analysis of road vehicle comfort and handling performances with respect to suspension technological parameters. The envisaged suspension being of semi-active nature, this implies first to consider an hybrid modeling approach consisting of a 3D multibody model of the full car - an Audi A...

The internal forces in the human body in motion could provide valuable information for the evaluation and follow-up of subjects with musculo-skeletal pathologies, such as scoliosis, but are still difficult to accurately measure. In this context, the objective of this study is to quantify the global intervertebral torques along the spine during walk...

In this paper, the dynamics of multibody systems with closed kinematical chains of bodies is considered. The main focus is set on non-linearity of the multibody equations with respect to the Lagrange multipliers. When closed chains are considered, loop cutting procedure is a solution to express the constraint equations associated with the loops. Dy...

Applying optimization techniques in the field of multibody systems (MBS) has become more and more attractive considering the increasing development of computer resources. One of the main issues in the optimization of MBS concerns closed-loop systems which involve non-linear assembly constraints that must be solved before any analysis of the system....

On classical passenger trains, the secondary suspension is commonly ensured by airsprings which are integrated in a pneumatic circuit. In addition to the pneumatic bellows, the circuit contains various pneumatic components such as tanks, pipes, orifices, levelling valves, etc., the purpose of the latter being to maintain a constant height between t...

The accurate quantification of internal efforts in the human body is still a challenge in biomechanics. The aim of this study is to quantify the intervertebral efforts along the spine during walking, in order to compare the dynamical behaviours between a healthy and a scoliotic subject. Practically, one healthy subject, one scoliotic patient before...

The accurate quantification of internal efforts in the human body is still a challenge in biomechanics. The aim of this study is to quantify the intervertebral efforts along the spine during walking, in order to compare the dynamical behaviours between a healthy and a scoliotic subject. Practically, one healthy subject, one scoliotic patient before...

Modeling mechatronic multibody systems requires the same type of methodology as for designing and prototyping mechatronic devices: a unified and integrated engineering approach. Various formulations are currently proposed to deal with multiphysics modeling, e.g., graph theories, equational approaches, co-simulation techniques. Recent works have poi...

This article presents a multidisciplinary approach of railway pneumatic suspension modelling: both multibody and pneumatic aspects are taken into account. The work aims at obtaining a realistic model of the secondary suspension and coupling it with a multibody model of a train. Various components of the pneumatic circuit such as bellows, tanks, pip...

This chapter of the book is devoted to teaching the discipline of Multibody Dynamics. This discipline concerns young students (baccalaurean) as well as more senior students (master’s degree, and even PhD degree). The first part of this chapter is strongly inspired by various opinions, which are also those of the authors of this chapter. In particul...

Modeling mechatronic multibody systems requires the same type of methodology as for designing and pro- totyping mechatronic devices: a unified and integrated engineering approa ch. Various formulations are currently proposed to deal with multiphysics modeling, e.g. graph theories, e quational approaches, co- simulation techniques. Recent works have...

The goal of this research project is to analyze the performances of a modern ve-hicle equipped with a novel suspension system linking front, rear, right and left cylinders via a semi-active hydraulic circuit, developed by Tenneco Automotive. In addition to improving the vehicle's vertical performances (in terms of comfort), the car body roll motion...

1. Abstract This paper presents a simple approach to optimize the dimensions and the positions of 2D mechanisms for path or function-generator synthesis. The proposed method is particularly adapted to assembled mechanisms since time-varying dimensions always satisfy the assembly conditions which may represent a real difficulty when dealing with clo...

This paper presents a student project which takes place just after the lecture in classical mechanics for undergraduate students in engineering. The pedagogical objectives of this learning layer cover various aspects, namely: give the student the opportunity to exploit and analyze the equations of motion for a real application, make them able to fo...

This paper describes an original and robust method to optimize the design of closed-loop mechanisms, especially parallel manipulators. These mechanisms involve non linear assembling constraints. During optimization, the Newton-Raphson algorithm we use to solve these constraints may fail when the Jacobian matrix of the constraints is ill-conditioned...

RESUME Depuis 8 ans, la Faculté des Sciences Appliquées de l'Université catholique de Louvain en Belgique a cons-truit une formation en mécatronique autour d'un apprentissage par projet consistant en la conception et réalisation de robots mobiles autonomes capables, à terme, de participer à des compétitions de robotique. Cet article présente une ré...

This paper describes a multibody simulation project, developed at the Université Catholique de Louvain and at the Universidad San Fransisco de Quito, as an additional “learning layer” for students in engineering. The projects are all based on the use of a symbolic multibody software for generating the equations of motion of real-world applications...

The present approach aims at using the principle of redundant actuation for parallel robotic structures in order to follow complex trajectories in a so-called mechanically advantageous way, meaning that for any trajectory configuration the actuators can bear important loads (internal and/or external). Multibody system formalisms using relative coor...

Procedures for modelling multibody systems are well known and many formulations and tools are available for these types of systems. For several years, emphasis has been placed on the modelling of electromechanical systems, particularly multibody systems, such as robots, which are driven by electrical actuators. In this paper, three different unifie...

Road vehicles represent an important class of multibody systems, all the more interesting since recent developments in this field rely on dynamical properties (stability, riding comfort, etc.). From the mechanical point of view, a vehicle is intrinsically of a multibody nature. Depending on the application, the model refinement can vary noticeably,...

Vehicles — on road or on track — certainly represent one of the most important types of application of the multibody approach. In the case of railway vehicles, an arduous aspect of the modeling phase results from the contact between the wheels and the track. Indeed, from a purely geometrical point of view, locating the contact point between a wheel...

Before the appearance of efficient computer architectures for scientific numerical computations, only analytical methods were available for modeling systems. The analyses often used rather restrictive hypotheses (truncated and/or linearized models, for instance). The emergence of powerful processors and reliable and user-friendly languages and soft...

The aim of this chapter is to describe the motion of several bodies. The fundamental notions of generalized coordinates, constraints and degrees of freedom will be introduced and illustrated via simple examples. Then, we shall develop the Newton-Euler procedure which produces the equations of motion relating the motion of the bodies (i.e. the evolu...

The aim of this section is to introduce the notations that will be used throughout this book for representing vectors, tensors as well as their time derivatives. It is assumed that the reader is familiar with elementary vector and matrix calculus. Basic properties of vectors and tensors will thus be recalled without proofs.

A multibody system (mbs) is a set of N body rigid bodies interconnected by joints. As illustrated in figure 3.1, mechanisms, road and railway vehicles, industrial or space manipulators, etc... are typical examples of multibody systems.

Flexibility effects in multibody dynamics certainly represent one of the most arduous aspects of the modeling of mechanical systems. There are several reasons for this. First of all, contrary to the rigid case, flexible bodies require both physical and geometrical hypotheses (e.g.: elastic linear behavior, small flexible motion, ...) whose validity...

The preceding chapter dealt with multibody systems having a tree-like structure. However, in many practical cases, physical systems are not tree-like. Road vehicle suspensions, anthropomorphic and parallel robots, railway bogies, etc. are multibody systems whose topology is not tree-like.

From an examination of system {4.1, 4.2, 4.3}, it readily appears that the equations of motion of constrained multibody systems are not only differential but differential-algebraic equations, abbreviated as DAEs [65], [40]. Time integration of DAEs has already been approached within the field of multibody dynamics using constraint stabilization [2]...

Cam/follower devices are used in a wide spectrum of applications, especially in automatic machines and instruments, textile machinery, printing presses, food-processing equipment, internal combustion engines, control systems, ... They constitute a simple and economic device with few movable parts. It is possible to design a cam such that the follow...

I Theory.- 1 Fundamental Mechanics.- 2 Dynamics of rigid bodies.- 3 Tree-like multibody structures.- 4 Complex multibody structures.- 5 Symbolic generation.- II Special topics.- 6 Road vehicles: wheel/ground model.- 7 Railway vehicles: wheel/rail model.- 8 Mechanisms: cam/follower model.- 9 Multibody systems with flexible beams.- 10 Time integratio...

This paper presents a multibody formalism using a minimal set of dynamicalparameters, based on the barycentric approach. Using relative jointcoordinates, we show that it is possible to generate recursively the inverseand direct dynamics in terms of this minimal set, rather than using theclassical ones (mass, centre of mass and inertia matrix). More...

The Center for Research in Mechatronics of the Universite catholique de Louvain aims to develop an integrated methodology for the design of mechatronic systems. Due to the complexity of the new systems and the required performances, it is no longer possible to optimize each aspect separately, one at a time. These systems should be considered as mul...

Developments in the field of symbolic generation in terms of multibody systems (MBS) modeling, CPU performance and software portability were presented. The developments were interpreted as a potential of the symbolic approach in multibody dynamics having a common denominator of fully symbolic generation of models. It was shown that the use of multi...

The modeling and control of redundantly actuated closed-loop mechanical systems is considered in the present work an illustrated with a planar four-bar mechanism and a 3-D parallel manipulator. A specific trajectory involving singular configurations is generated and then followed using the overactuation. To generate the trajectory, four-degree poly...

The needs for analyzing vehicle dynamics rely on advanced modelling techniques, efficient program implementation and high-level computer environment. To match these requirements, two important assets should characterize modern modelling tools: computer efficiency (indispensable, for instance, for real time control or system optimization) and portab...

This paper presents a new concept of dynamically stable walking robots. The main idea is to stabilize the robot by applying the "spinning-top principle", using a rotating mass at the top of the robot. This first study considers a rubber foot at the base of each leg and we model it with a compliant contact between the leg and the ground. The model a...

This paper proposes a formulation for modelling mechanisms witha cam/follower type of contact using a multibody approach in relativecoordinates. The proposed approach is inspired from the wheel/railcontact model developed by Fisette and Samin but, in the present case,possible intermittent contact between the cam and the follower isconsidered, for g...

Typical mobile robot structures (e.g., wheelchair or car-like robots) do not have the required mobility for common applications such as displacement in a corridor, hospital, office, etc. New structures based on the ‘universal wheel’ (i.e., a wheel equipped with free rotating rollers) have been developed to increase mobility. However, these structur...

The paper presents an approach for the synthesis, analysis and optimisation of 3-axis machine tool concepts. The machine tool configurations are described by ten configurational parameters. The machine variants are assembled from components having parametric shapes and dimensions. Three analyses are developed for the evaluation of the generated mac...

La conception intégrée de systèmes combinant mécanique, génie électrique, informatique et automatique constitue une nouvelle discipline, la mécatronique, que la faculté des Sciences Appliquées de l'Université catholique de Louvain (UCL) a décidé depuis trois ans d'enseigner dans le cadre d'un nouveau diplôme en électromécanique, orientation mécatro...

The needs for analyzing vehicle dynamics rely on advanced modelling techniques, efficient program implementation and high-level computer environment. To match these requirements, two important assets should characterize modern modelling tools: computer efficiency (indispensable, for instance, for real time control or system optimization) and portab...

The modelling of flexible elements in mechanical systems has been investigated via several methods issuing from both the field of multi-body dynamics and the area of structural mechanics and vibration theory. As regards the multibody approach, recursive formulations in relative coordinates are quite suitable and efficient for a large variety of app...

Typical mobile robot structures (e.g. wheelchair or car-like, ...) do not have the required mobility for common applications such as displacement in a corridor, hospital, office, ... New structures based on the "universal wheel" (i.e. a wheel equipped with free rotating rollers) have been developed to increase mobility. However, these structures ha...

In spite of the continuous and sustained increase in CPU-time performances of modern computer processors, one notes a real eagerness in the scientific community to investigate both the vector and parallel computational approaches. The goal is obviously to attain high-speed simulation whatever the envisaged numerical treatment may be. The aim of the...

The modelling of flexible elements in mechanical systems has been investigated through several methods issuing from both the field of multi-body dynamics and the area of structural mechanics and vibration theory. Concerning the multibody approach, recursive formulations in relative coordinates have been widely claimed to be most suitable and effici...

This contribution highlights the potentialities of the symbolic approach in multibody dynamics through the use of the ROBOTRAN program [1], specially developed for multibody system analysis. Whatever the mechanical system to be analysed (mechanisms, robots, vehicles,...), it can be considered as a set of bodies connected by joints and submitted to...

Typical mobile robot structures (e.g. wheelchair or car-like, …) do not have the required mobility for common applications such as displacement in a corridor, hospital, office… New structures based on the "universal wheel" (i.e. a wheel equipped with free rotating rollers) have been developed to increase mobility. However, these structures have imp...

The modelling of flexible elements in mechanical systems has been widely investigated through several methods issuing from both the area of structural mechanics and the field of multibody dynamics. As regards the latter discipline, beside the problem of the generation of the multibody equations of motion, the choice of a spatial discretization meth...

The modelling of flexible elements in mechanical systems has been investigated via several methods issuing from both the field of multibody dynamics and the area of structural mechanics and vibration theory. A multibody approach using a recursive formalism in relative coordinates is adopted here. While leading to a highly non-linear system with a d...

The efficient computation of multibody systems dynamic equations certainly remains of a great importance in so far as both the increasing size and refinement of the mathematical models lead to a high complexity of the equations to be solved. Among the various multibody formalisms developed and implemented into computer programs, one generally admit...

The modelling of constrained multibody systems has been widely studied, published and implemented into computer programs, using different formalisms and terminologies. The resulting equations are formally of a mixed nature, viz. differential-algebraic, and cannot be directly solved by classical integrator schemes.Among the various techniques propos...

The aim of this paper is to show that multibody systems with a large number of degrees of freedom can be efficiently modelled, taking conjointly advantage of a recursive formulation of the equations of motion and of the symbolic generation capabilities. Recursive schemes are widely used in the field of multibody dynamics since they avoid the “explo...

The dynamic model of tree-like multibody systems is linear with respect to the parameters of mass distribution for instance when barycentric parameters are used. Thus, assuming that the parameters related to the kinematics are perfectly known, these quantities can be estimated through linear regression techniques. The necessary data are obtained by...

The classical mathematical models and the corresponding multibody programs are not always adapted to the increasing diversity of railway bogie designs, since the most general envisaged case consists of a carbody (or several) carried by two rigid bogies equipped with wheelsets. Although the latter configuration still represents the major pan of the...

The dynamic model of a robot manipulator is linear with respect to the parameters of mass distribution when e.g. barycentric quantities are used. Based on the notion of barycentric parameters, recursive rules have been established to find the minimal set of parameters occurring in the equations of motion of serial-link robots. The aim of the presen...

The aim of this paper is to show that multibody systems with a large number of degrees of freedom can be efficiently modelled, taking conjointly advantage of a recursive formulation of the equations of motion and of the symbolic generation capabilities. Recursive schemes are widely used in the field of multibody dynamics since they avoid the “explo...