Denis Rancourt

Université de Sherbrooke | UdeS · Department of Mechanical Engineering

Knowledge of frame loads at the limits of the intended driving conditions is important during the design process of a vehicle structure. Yet, retrieving these loads is not trivial as the load path between the road and the frame mounting point is complex. Fortunately, recent studies have shown that multibody dynamic (MBD) simulations could be a powe...

Knowledge of frame loads at the limits of the intended driving conditions is important during the design process of a vehicle structure. Yet, retrieving these loads is not trivial as the load path between the road and the frame mounting point is complex. Fortunately, recent studies have shown that multibody dynamic (MBD) simulations could be a powe...

The design of a vehicle frame is largely dependent on the loads applied on the suspension and heavy parts mounting points. These loads can either be estimated through full analytical multibody dynamic simulations, or from semi-analytical simulations in which tire and road sub-models are not included and external vehicle loads, recorded during field...

Joint mechanical impedance is commonly measured by applying dynamic perturbations about a joint at a fixed operating point/background torque, and quantifying torque change vs. angle change. Impedance characterization in functional tasks, therefore, requires multiple experimental trials over a range of operating points—a cumbersome, invasive, time-c...

Pushing capacity is a key parameter in athletic racing wheelchair performance. This study estimated the potential contribution of upper limb momentum to pushing. The question is relevant since it may affect the training strategy adopted by an athlete. A muscle-free Lagrangian dynamic model of the upper limb segments was developed and theoretical pr...

The present contribution is dedicated to the identification of mechanical parameters, especially time varying parameters for vibrating structures. The approach is experimentally illustrated with vertical beam having a time varying torsional stiffness (1-DOF mechanical system). In many identification techniques, space/time derivatives and noise sens...

Existing commercial hand prostheses can be controlled from the electrical activity (electromyogram or EMG) of remnant muscle tissue within the forearm, but are limited in function to one degree of freedom of proportional control. In a pilot study (N=3 subjects), we used least squares estimation to identify a model between forearm electrical activit...

Electromyogram (EMG) activity from the extensor and flexor muscles of the forearm was sensed with high-density surface electrode arrays and related to the force produced at the four fingertips during constant-posture, slowly force-varying contractions from three healthy subjects. Various electrode montages (spatial filters) and number of electrodes...

Electromyogram (EMG)-torque modeling is of value to many different application areas, including ergonomics, clinical biomechanics and prosthesis control. One important aspect of EMG-torque modeling is the ability to account for the joint angle influence. This manuscript describes an experimental study which relates the biceps/triceps surface EMG of...

Abstract This article introduces a sit-ski developed for the Canadian Alpine Ski Team in view of the Vancouver 2010 Paralympic games. The design is predominantly based on controlling the mass distribution of the sit-ski, a critical factor in skiing performance and control. Both the antero-posterior location of the centre of mass and the sit-ski mom...

Hybrid III dummies used for collision testing in the automotive industry include passive hands that cannot produce any grasping force. Such capability would be useful in low-acceleration collisions or vehicle tipover investigations, since grasping force and hand stiffness may impact the dummy movements during impact. In the context of studying the...

This paper introduces a parameter identification method for linear time-varying systems that is based on the derivative formulation of the Chebyshev polynomial basis. A dynamic system matrix representation is first developed for N-DOF mechanical systems having multiple time-varying parameters. The method is then applied to a numerical simulation of...

Numerical simulation of soft tissue mechanical properties is a critical step in developing valuable biomechanical models of live organisms. A cubic Hermitian spline optimization routine is proposed in this paper to model nonlinear experimental force-elongation curves of soft tissues, in particular when modeled as lumped elements. Boundary condition...

We provide a preliminary report on work to relate the EMG activity from forearm flexors and extensors to the flexion-extension forces generated at the finger tips during constant-posture, slowly force-varying contractions. EMG electrode arrays (up to 64 channels) were applied over the flexor and, separately, extensor musculature of the forearm. Spa...

This paper describes an experimental study which relates the simultaneous biceps/triceps surface electromyogram (EMG) of 12 subjects to elbow torque at seven joint angles during constant-posture, quasi-constant-torque contractions. Advanced EMG amplitude (EMGσ) estimation processors were investigated, and an EMG-torque model considering agonist and...

Back pain is a common complaint that may result from the use of an inappropriate mattress. It can be minimized by using a well suited mattress. This paper presents a method for designing a custom foam mattress in an attempt to reduce back pain for the lateral lying position. Body three-dimensional profile and its mass distribution are both estimate...

To interact mechanically with the world and especially to use hand tools we exert force. However, the biomechanical consequences of force production can be challenging. In particular, due to the nonlinear kinematics of the mammalian skeleton and of typical hand tools, exerting force can destabilize posture, compromising the ability to control force...

This chapter presents a modeling approach for soft tissue properties designed at Laval University as part of the development of a simulation system for liver surgery. Surgery simulation aims at providing physicians with tools allowing extensive training and precise planning of interventions. The design of such simulation systems requires accurate g...

Single-mode device-to-fiber alignment automation is usually achieved with a classical mathematical optimization approach. We present a different approach, which is based on the identification of particular intrinsic characteristics of the coupled optical power and on estimating residual axial, transverse, and angular misalignments in the far field....

Numerous studies have investigated the relationship between surface electromyogram (EMG) and torque exerted about a joint. Most studies have used conventional EMG amplitude (EMGamp) processing, such as rectification followed by low-pass filtering, to pre-process the EMG before relating it to torque. Recently, advanced EMGamp processors that incorpo...

Continuing a previous analytical and numerical work, an experimental investigation of seven intrinsic properties of the optical coupling between axisymmetric Gaussian beams is presented. In this study, two single-mode fibers are used as the receiver and the emitter and a five-axis nanopositioning system is used to investigate optical coupling prope...

The relationship between surface EMG and torque about a joint has been the focus of many studies. Some of these studies however, have utilized conventional processors to obtain the EMG amplitudes. Recent advances (multiple channel combination and whitening) have demonstrated significant improvement in EMG amplitude estimation accuracy. The purpose...

In this work, we introduce an extension of the linear elastic tensor-mass method allowing fast computation of non-linear and visco-elastic mechanical forces and deformations for the simulation of biological soft tissue. We aim at developing a simulation tool for the planning of cryogenic surgical treatment of liver cancer. Percutaneous surgery simu...

Precise geometric reconstruction is a valuable tool in the study of soft tissues biomechanics. Optical methods have been developed to determine the tissue cross section without mechanical contact with the specimen. An adaptation of the laser micrometer developed by Lee and Woo [ASME J. Biomech. Eng., 110 (2), pp. 110-114]. is proposed in which the...

In the rapidly growing field of tissue engineering, the functional properties of tissue substitutes are recognized as being of the utmost importance. The present study was designed to evaluate the effects of static mechanical forces on the functionality of the produced tissue constructs. Living tissue sheets reconstructed by the self-assembly appro...

On the basis of the overlap integral method, an approximate analytical model is derived to estimate the coupled optical power between axisymmetric Gaussian beams when transverse, axial, and angular misalignments simultaneously exist in three dimensions. Seven optical properties are derived from a detailed analysis of the model. Because the model is...

The SKALPEL-ICT project (Simulation Kernel Applied to the Planning and Evaluation of Image-guided Cryotherapy) aims at the developing of a virtual environment for the simulation of liver cancer cryotherapy. This simulator will mainly be used to plan the configuration and the positioning of the cryo-probes for an image-guided cryo-surgical intervent...

Abstract: Anterior cruciate ligament (ACL) injuries occur at an annual rate of 120000 in the USA, and many need reconstructive surgery. We report successful results at 1-13 months following implantation of bioengineered ACL (b ACL) in goats. A bACL has been developed using autologous ACL cells, a collagen matrix and bone plugs. The extremities of t...

We describe extensions of the tensor-mass algorithm allowing fast computation of nonlinear and visco-elastic mechanical forces and deformations for the simulation of biological soft tissue. This work is part of a broader project aiming at the development of a simulation tool for the planning of cryogenic surgical treatment of liver cancer. Real-tim...

Anterior cruciate ligament (ACL) injuries occur at an annual rate of 120 000 in the USA, and many need reconstructive surgery. We report successful results at 1–13 months following implantation of bioengineered ACL (bACL) in goats. A bACL has been developed using autologous ACL cells, a collagen matrix and bone plugs. The extremities of the bACL we...

High-speed transmission optical devices and equipment often use a single-mode fiber as receiver or emitter. The fiber must be accurately aligned over five degrees of freedom with respect to an optical field. In this paper, we investigate a model-based approach which takes advantage of the properties of the optical coupling physical phenomenon. Usin...

Cabin noise and structural vibrations are increasingly important issues in the aircraft industry. Design of improved engine mount systems can help reduce cabin noise and vibration transmissibility. The design challenge is to properly tune the mounts such that they are at their maximum performance in flight conditions. Given the complexity of modeli...

We introduce an extension of the linear elastic tensor-mass method which allows fast computation of non-linear and viscoelastic mechanical deformations, and is suitable for the simulation of biological soft tissue deformation. We aim at developing a simulation tool for the planning of cryogenic surgical treatment of liver cancer. Percutaneous surge...

A standing individual can use several strategies for modulating pushing force magnitude. Using a static model, researchers have shown that the efficacy of those strategies varies considerably. In the present article, the authors propose a human motor control dynamic model for analyzing transients that occur when an individual is asked to modulate f...

The sections above have described an EMG amplitude estimator and an initial application of this estimator to the EMG-torque problem. The amplitude estimator consists of six stages. In the first stage, motion artifact and power-line interference are attenuated. Motion artifact is typically removed with a highpass filter. Elimination of power-line no...

The human skin contains a physiological battery that could be implicated in the healing process, by creating an endogenous electric field. Skin cells undergo morphological changes in response to an external DC electric field (EF). We found that fibroblasts reorient their cell bodies in a manner perpendicular to the EF direction, for normal and abov...

Recent epidemiological studies report that obesity is positively related to fracture incidence. In the present experiment, a model of postural control was used to examine the impact of an abnormal distribution of body fat in the abdominal area upon postural stability. Obese and lightweight humanoids were destabilized by imposing a small initial ang...

Exerting a force on a mechanical system can induce mechanical instability. To overcome that instability, humans may take advantage of their upper limb mechanical impedance (e.g., hand stiffness). The authors investigated what stiffness is required to maintain static stability and how humans can achieve that stiffness in the context of the task of p...

This paper applies orientation statistics to investigate variations in upper limb pose of human subjects drilling at 6 dierent locations on a vertical panel (cf. Figure 2). Some of the drilling locations are kinematically equivalent in the sense that the same pose could be used for these locations. Upper limb pose is measured by recording the coord...

The purpose of this work was to determine the optimal EMG-torque relationship using four different EMG processors in conjunction with different system identification (ID) techniques for dynamically torque varying elbow constant angle contractions. Comparing predicted torque with actual elbow torque, it was found that either multiple EMG channels or...

Our research group has been investigating the effect of cyclic deformations on the evolution of fibroblast populated collagen gels (FPCG). Since existing traction machines are not designed for such an application, we had to design a cyclic traction machine adapted to tissue culture inside an incubator over an extended period of time. Biocompatible...

A systematic, experimental study of the influence of smoothing window length on the signal-to-noise ratio (SNR) of electromyogram (EMG) amplitude estimates is described. Surface EMG waveforms were sampled during nonfatiguing, constant-force, constant-angle contractions of the biceps or triceps muscles, over the range of 10%-75% maximum voluntary co...

A new substructuring technique is proposed to perform vibration analysis of line-coupled structures. In dividing the whole structure into a master structure and several auxiliary structures, a variational formulation is used to model the master structure, enabling one to introduce the effects of all auxiliary structures by using their compliance ch...

This paper presents an experimental assessment of the Tip Excitation Technique (TET) introduced in a companion paper. The aim of the technique is to measure the rotational compliance of attached plane structures. Following the guidelines established on the basis of a numerical study in the companion paper, experimental measurements were performed o...

Tissue bioengineering has attracted considerable interest in the biological and medical fields, notably in orthopaedics. In United States alone at least 90 000 patients per year undergo ligament reconstruction [39]. As is often reported, in contrast with the medial collateral ligament, anterior cruciate ligament (ACL) regeneration is hampered in vi...

Describes the results of a study on the influence of smoothing window length on the signal-to-noise ratio (SNR) of electromyogram (EMG) amplitude estimates. In a previous experiment, surface EMG waveforms were recorded for non-fatiguing, constant-force, isometric contraction of the biceps and triceps muscles. Based on these data, four different EMG...

Friction tests between cancellous bone cubes and porous-surfaced metal plates were conducted in order to determine the mechanical properties of the interface in a knee porous-surfaced metal implant. Bone specimens were obtained from fresh frozen amputated tibiae and three metal plates were chosen: titanium bead porous-surfaced, titanium fiber mesh...