Subhash Rakheja

Concordia University · Department of Mechanical and Industrial Engineering

Hydro-Pneumatic Struts (HPS) are widely implemented in automobile, aerospace, and construction industries, mainly for the purpose of vibration and shock absorption. The HPS design with integrated gas-oil chamber is relatively more compact and robust, while mixing gas and oil inside the HPS generates gas-oil emulsion and more nonlinearities. This st...

An improved YOLOv8 detection method is proposed for detecting distracted driving behavior and driver’s emotion. Unlike the commonly used YOLOv8 method, an attention mechanism named MHSA and a CNN module are synthesized to ensure improved performance in terms of accuracy and convergence, where MHSA is used to detect distracted driving behavior and C...

This paper presents a novel modeling approach to predict the nonlinear dynamic characteristics of automotive mounts and shock absorbers. Firstly, the concept of the hybrid ANN (artificial neural network)–mechanical modeling approach is presented, which consists of an equivalent mechanical model to characterize the trend of the dynamic characteristi...

Hydro-pneumatic suspension (HPS) systems are increasingly being implemented in commercial vehicles and various industrial equipment, which is mainly attributed to the integration of adaptable nonlinear pneumatic stiffness and hydraulic damping properties. The integrated HPS design with a shared gas-oil chamber, however, leads to gas-oil emulsion fl...

This study investigated the effects of gender and ten different anthropometric parameters on the vertical vibration transmission from seat to the head of the body seated on an elastic seat. The seat-to-head transmissibility (STHT) responses in the vertical and fore-aft directions of 58 participants (31 males and 27 females) were measured under thre...

This study investigated the seat-to-head vibration transmissibility (STHT) responses of 58 subjects (31 males and 27 females) seated on three different elastic seats with (WB) and without back support (NB) and under three levels of vertical vibration (0.25, 0.50 and 0.75 m/s2 RMS) in the 0.50–20 Hz range. The STHT responses with elastic seats were...

Hydro-pneumatic suspension (HPS) systems is increasingly being implemented on commercial vehicles, mainly attributing to the integration of adaptable nonlinear pneumatic-stiffness and hydraulic-damping properties. The integrated HPS design with shared gas-oil chamber, however, leads to gas-oil emulsion flow within the suspension chambers which intr...

Serpentine belt accessory drive system (SBADS) is a complex hybrid discrete-continuous system and is a typical coupled vibration system with rigid body vibrations and belt vibrations, which consists of rotational vibrations of pulleys and tensioner arm and transverse vibrations of continuum belt spans. Taking an engine front end accessory drive sys...

The nonlinear axial friction force (NAFF) induced by contact and friction between components of tripod joints constitutes an important dynamic characteristic of drive-shaft systems, which will lead to deterioration of the NVH (noise, vibration and harshness) performance of the vehicle. Based on the fractal theory, this paper proposes a novel modeli...

The paper aims to establish analytical models for air spring with an auxiliary chamber (ASAC) to study the nonlinear characteristics of ASAC systems in the time domain. A test bench is built for measuring the dynamic characteristics of an ASAC, and the transmitted force of an ASAC is measured if harmonic and transient step displacements are applied...

The article presents a novel mathematical model to analyze the performance of convoluted air springs (CAS) with different numbers of bellows. The proposed mathematical model considers both the effects of bellow’s tensile deformation and the asymmetric structural features. Some key parameters such as effective area, volume, and their variation rates...

This study proposes a methodology for evaluating the integrated performance of vibration reducing (VR) gloves considering four measures. These include manual dexterity, distributed palm and fingers vibration transmission and grip strength preservation, which generally pose conflicting design requirements. The weights for the conflicting performance...

The axial friction force (AFF) of automotive drive-shaft systems is an important nonlinear dynamic characteristic, which will directly cause the vibration and noise of vehicles. During the operation of drive-shaft systems, the AFF has great uncertainty. Taking a drive-shaft system as the research object, a hybrid random and interval uncertainties (...

This study investigates the angle tracking control of the electric power steering system, which is underactuated and with (possibly fast) time-varying uncertainties. We design the control based on constraint-following, that is, formulating the tracking goal as servo constraints. To tackle the uncertainty, especially the mismatched uncertainty, a ro...

In the design of a drive-shaft system, the magnitude of the generated axial force (GAF) by the tripod joint constitutes an important design goal. Owing to the uncertainties associated with the drive-shaft system operating environment, and dimensional and material parameters, the GAF exhibits considerable uncertainty. In this study, a comprehensive...

Objective: The primary aim was to test the construct validity of a surface electromyography (EMG) measurement protocol, indirectly assessing the effects of anti-vibration (AV) gloves on activities of the forearm muscles. Background: AV gloves impose a relatively higher grip demand and thus a higher risk for musculoskeletal disorders. Consequentl...

The drive shaft system with a tripod joint is known to cause lateral vibration in a vehicle due to the axial force generated by various contact pairs of the tripod joint. The magnitude of the generated axial force, however, is related to various operating factors of the drive shaft system in a complex manner. The generated axial force due to a driv...

A wavelet transform-based spectrum editing method is proposed for deriving effective load spectrums for accelerated durability testing of mechanical components. A modified down-sampling algorithm is also proposed for pre-processing of a measured load spectrum for preserving peaks and valleys in the original spectrum by reassigning the neglected pea...

The damping characteristics of a magneto-rheological damper featuring non-magnetized flow paths in the piston are analysed using the Eyring constitutive model considering both viscous and minor hydraulic losses. The force–displacement and force–velocity characteristics of the magneto-rheological damper with non-magnetized flow paths were experiment...

This study focuses on the integrated performance of anti-vibration (AV) gloves in terms of manual dexterity and distributed palm and fingers’ vibration transmissibility. Experiments were designed to measure vibration transmission and manual dexterity performance of 10 different gloves using 15 subjects. The results showed all gloves impeded manual...

Hydro-pneumatic suspension (HPS) systems could attenuate broad-frequency-range vibration mainly via the nonlinear hydraulic damping property. While the strut design with shared gas-oil chamber leads to gas-oil emulsion within strut chambers which intricately affects the fluid flows between the coupled chambers and thus the damping force. This study...

In the framework of whole-body vibration (WBV), biodynamics refers to biomechanical responses of the human body to impressed oscillatory forces or motions. The biodynamic responses of the human body to WBV form an essential basis for an understanding of mechanical-equivalent properties of the body and potential injury mechanisms, developments in fr...

A finite element model of a thin-walled foam-filled square tube is developed for estimating its energy absorption characteristics. The crush behavior of the foam-filled tube is experimentally evaluated under axial loading and the measured force-deflection properties are used to examine validity of the model. The validated model is subsequently appl...

Thin-walled structures are widely used as energy absorbers in automotive vehicles due to their lightweight and high-energy absorption efficiency. In order to improve the energy absorption characteristics of thin-walled structures subjected to different loading angles, different types of novel multi-cell structures are proposed in this paper. The nu...

A hybrid proportional electromagnetic dynamic vibration absorber consisting of an electromagnetic actuator and an elastic element is proposed for control of engine vibration during idling. The design of the proportional electromagnetic actuator is realized considering the geometric parameters of the core to achieve nearly constant magnetic force ov...

Design of a flexible thin-film hand sensor is presented for reliable measurements of the contact pressure/force distribution at a viscoelastic hand-handle interface, including the contact force developed by a gloved-hand grasping a tool handle. The static properties of the developed hand sensor were evaluated in terms of its drift, linearity, repea...

This paper studied a kind of off-highway truck suspension with simple structure of gas and oil sealed in same chamber. The mechanics characteristics of hydra pneumatic suspension are known to be coupled with the gas state, oil flow rate through orifice and friction force model. The reported studies on hydra pneumatic suspension involve flow rate co...

The purpose of this study was to evaluate the effects of anti-vibration gloves on manual dexterity and explore factors affecting the manual dexterity. The manual dexterity of ten different gloves was investigated with 15 adult male subjects via performing two different dexterity tests, namely, ASTM F2010 standard test and Two-Hand Turning and Placi...

The nonlinear stiffness and damping properties of a simple and low-cost design of a hydro-pneumatic suspension (HPS) strut that permits entrapment of gas into the hydraulic oil are characterized experimentally and analytically. The formulation of gas-oil emulsion is studied in the laboratory, and the variations in the bulk modulus and mass density...

For general-purpose passenger cars with a manual transmission, breakaway performances of a clutch have great effects on ride of clutch operation system. Breakaway performances of a clutch is defined as force versus displacement applied at clutch fingers, and it is nonlinear decided by nonlinear characteristics of diaphragm spring and waveform plate...

The gender and anthropometric effects on vibration absorbed power characteristics of the seated body are investigated through measurements with 31 males and 27 females considering two different back support conditions, and three levels of vertical vibration (0.25, 0.50, and 0.75 m/s² rms acceleration) in the 0.5–20 Hz frequency range. The absorbed...

This study investigates the coupled ride and directional performance characteristics of an articulated frame-steered vehicle (AFSV). A three-dimensional multi-body dynamic model of the vehicle is formulated integrating the hydro-mechanical frame steering and hydro-pneumatic suspension (HPS) systems. The model parameters are obtained from field-meas...

A nonlinear torsional model for a driveline system with 4 degrees of freedom is proposed for studying gear rattle if a car is at idle. The time-varying meshing stiffness of geared teeth, gear backlash, and the damping from oil film are included in the model. The dynamic responses of the driveline system, such as clutch angular displacement, meshing...

The vibration isolation performances of vibration reducing (VR) gloves are invariably assessed in terms of power tools’ handle vibration transmission to the palm of the hand using the method described in ISO 10819 (2013), while the nature of vibration transmitted to the fingers is ignored. Moreover, the VR gloves with relatively low stiffness visco...

The articulated frame-steered vehicles (AFSV) exhibit enhanced maneuverability but reduced yaw stability and greater steering power consumption. Apart from kinematics of the steering system, the dynamics of the actuating system strongly influence the performance of the AFSV, which is generally neglected in the reported studies. In this study, a yaw...

The directional performance characteristics of articulated frame steering vehicles are known to be strongly coupled with the kinematic characteristics and the dynamic characteristics of the steering system. The reported studies on articulated frame steering generally focus on the yaw divergence behaviour or the snaking tendency of the vehicle based...

Designs and analyses of seat-suspension systems are invariably performed considering effective vertical spring rate and damping properties, while neglecting important contributions due to kinematics of the widely used cross-linkage mechanism. In this study, a kineto-dynamic model of a seat-suspension is formulated to obtain relations for effective...

This study is aimed at characterizing the nonlinear stiffness and damping properties of a simple and low cost design of a hydro-pneumatic suspension (HPS) that permits entrapment of gas into the hydraulic fluid. The mixing of gas into the oil yields highly complex variations in the bulk modulus, density and viscosity of the hydraulic fluid, and the...

Vibration attenuation performance of vibration reducing (VR) gloves is, invariably, measured at the palm using the method described in ISO 10819 (2013). The standardized method, however, does not address the glove performance in terms of fingers vibration, which is substantially different from that of the palm. An investigation was conducted to enh...

The natural frequency of a rubber-damped torsional vibration absorber (TVA) depends on the excitation amplitudes and frequencies in a highly nonlinear manner. This is due to nonlinear shear properties of the rubber ring. In this study, the nonlinear static and dynamic shear characteristics of a rubber ring, and the natural frequency of a nonlinear...

The roll stability is significant for both road and off-road commercial vehicles, while the majority of reported studies focus on road vehicles neglecting the contributions of uneven off-road terrains. The limited studies on roll stability of off-road vehicles have assessed the stability limits using performance measures derived for road vehicles....

This study explored the feasibility of the flexible resistive (FlexiForce) force sensors for measurement of the hand-arm biodynamic response. Two FlexiForce sensors were installed on an instrumented handle to measure the palm-handle and finger–handle interface dynamic forces. The measurements were performed with six subjects grasping a 38 mm diamet...

Unlabelled: Apparent mass (AM) responses of the body seated with and without a back support on three different elastic seats (flat and contoured polyurethane foam (PUF) and air cushion) and a rigid seat were measured under three levels of vertical vibration (overall rms acceleration: 0.25, 0.50 and 0.75 m/s(2)) in the 0.5 to 20 Hz range. A pressur...

The absorbed power characteristics of seated body exposed to whole-body vibration along the individual and combined fore-aft (x), lateral (y) and vertical (z) axes are investigated through measurements of body-seat interactions at the two driving-points formed by the body and the seat-pan, and upper body and the seat backrest. The experiments invol...

The hysteresis nonlinearities of a magnetostrictive actuator were characterized under different amplitudes of simple and complex harmonic excitations over a wide range of frequencies (10-200 Hz) and magnetic bias levels (35-75 kA m-1). The measured data revealed asymmetric output-input characteristics and strong dependence on the magnetic bias, amp...

The ride and directional stability properties of an articulated frame steer vehicle (ASV) are investigated through formulation of a comprehensive three-dimensional vehicle model. The model integrates a kineto-dynamic formulation of the frame steering system, a torsio-elastic rear axle suspension, and random roughness of two parallel terrain tracks....

Laboratory measurements were performed to characterize output-input characteristics of a magnetostrictive actuator under a wide range of input current amplitudes in the 10-200 Hz frequency range. The measurements revealed asymmetry in the output and output saturation under moderate and high amplitude current, and increasing hysteresis effects with...

Compared to the vehicles with conventional steering, the articulated frame steer vehicles (ASV) are known to exhibit lower directional and roll stability limits. Furthermore, the tire interactions with relatively rough terrains could adversely affect the directional and roll stability limits of an ASV due to terrain-induced variations in the vertic...

In this study, the biodynamic responses to vertical vibration are investigated in terms of seat-to-head vibration transmissibility (STHT) to study the effects of gender and eleven different anthropometric parameters on the STHT responses in the vertical and fore-aft directions. The STHT response of 31 male and 27 female human subjects were measured...

Magnetostrictive actuators invariably exhibit hysteresis nonlinearities that tend to become significant under high rates of inputs, and could cause oscillations and error in the micro-positioning tasks. This study presents a methodology for compensation of hysteresis nonlinearity in a magnetostrictive actuator subject to a wide range of input rates...

Compensation of hysteresis nonlinearity of smart actuators through applications of an inverse hysteresis model generally yields errors when coupled with a plant. In this study, the resulting compensation error is analytically derived considering the Prandtl-Ishlinskii model and its inverse, which has not yet been reported. The proposed analytical e...

The apparent mass and seat-to-head vibration transmissibility response functions of the seated human body were investigated under whole-body vibration exposures to fore-aft (x), lateral (y), and vertical (z) applied individually and simultaneously. The experiments were performed with 9 adult male subjects to measure the biodynamic responses to sing...

Increasing concerns on human driver comfort/health and emerging demands on suspension systems for off-road vehicles call for an effective and efficient off-road vehicle ride dynamics model. This study devotes both analytical and experimental efforts in developing a comprehensive off-road vehicle ride dynamics model. A three-dimensional tire model i...

Hand-transmitted vibration and the associated potential injuries are dependent on hand-arm posture, hand forces and other factors. This study presents biomechanical models consisting different substructures of the hand-arm system and the trunk of the body in different postures subject to zh-axis vibration. The trunk was considered in order to accou...

The objective of this study is to investigate the basic characteristics of the three axis mechanical impedances distributed at the fingers and palm of the hand subjected to vibrations along the three orthogonal directions (xh, yh, and zh). Seven subjects participated in the experiment on a novel three-dimensional (3-D) hand–arm vibration test syste...

The three volume set LNAI 7506, LNAI 7507 and LNAI 7508 constitutes the refereed proceedings of the 5th International Conference on Intelligent Robotics and Applications, ICIRA 2012, held in Montreal, Canada, in October 2012. The 197 revised full papers presented were thoroughly reviewed and selected from 271 submissions. They present the state-of-...

The three volume set LNAI 7506, LNAI 7507 and LNAI 7508 constitutes the refereed proceedings of the 5th International Conference on Intelligent Robotics and Applications, ICIRA 2012, held in Montreal, Canada, in October 2012. The 197 revised full papers presented were thoroughly reviewed and selected from 271 submissions. They present the state-of-...

Smart actuators employed in micropositioning are known to exhibit strong hysteresis nonlinearities, which may be asymmetric and could adversely affect the positioning accuracy. In this paper, the analytical inverse of a generalized Prandtl-Ishlinskii model is formulated to compensate for hysteresis nonlinearities of smart actuators. The generalized...

The ride dynamic characteristics of a novel torsio-elastic suspension for off-road vehicle applications are investigated through field measurements and simulations. A prototype suspension was realised and integrated within the rear axle of a forestry skidder for field evaluations. Field measurements were performed on forestry terrains at a constant...

The apparent mass and seat-to-head-transmissibility response functions of the seated human body were investigated under exposures to fore-aft (x), vertical (z), and combined fore-aft and vertical (x and z) axis whole-body vibration. The coupling effects of dual-axis vibration were investigated using two different frequency response function estimat...

The influences of damper asymmetry on the camber angle variations of a double wishbone type of suspension, together with the dynamic responses under measured urban road inputs at different vehicle velocities, were investigated. Simulation studies employing a kineto-dynamic quarter-car model comprising a bilinear damper revealed complex dependence o...

A low cost system based on two rigid thin film pressure sensors located on two sections of the handle between the operator hand and the tool handle is developed to evaluate coupling forces on real power tool handles. The proposed system is made of two custom FlexiForce® sensors from Tekscan Inc. and these sensors act as single distributed force sen...

Biomechanical models of the hand-arm system in the bent- and extended-arm postures subject to zh-axis vibration were applied to derive the energy distribution within different substructures of the hand-arm system. The parameters of the models were derived on the basis of both the driving-point impedance and vibration transmitted to different segmen...

Linear or nonlinear 2-degrees of freedom (DOF) quarter-car models have been widely used to study the conflicting dynamic performances of a vehicle suspension such as ride quality, road holding and rattle space requirements. Such models, however, cannot account for contributions due to suspension kinematics. Considering the proven simplicity and eff...

Piezoel ectric actuators exhibit limited tracking performance in precision control due to their inherent hysteresis nonlinearity. In this paper, the hysteresis behavior is described by a play operator-based Prandtl-Ishlinsk ii (PPI) model. And a corresponding stop operator-based Prandtl-Ishlinsk ii (SPI) model is utilized as a feedforward compensat...

The ride dynamics of typical North-American soil compactors were investigated via analytical and experimental methods. A 12-degrees-of-freedom in-plane ride dynamic model of a single-drum compactor was formulated through integrations of the models of various components such as driver seat, cabin, roller drum and drum isolators, chassis and the tire...

Identification of most probable ranges of biodynamic responses of the human body exposed to whole-body vibration is essential for developing effective integrated human-machine system design tools, improved vibration mitigation devices and frequency-weighting for exposure assessment. The international standard, ISO-5982 (2001), defines such ranges f...