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A control strategy based on H∞-type static output feedback combined with dynamic feed-forward is proposed to improve the high-speed lateral performance of an A-double combination vehicle(tractor–se...

Owing to the significant contribution of flexible modals in rigid-flexible multiple body system (MBS) dynamics, model updating before flex-body generation is necessary. Herein, a model-updating met...

For a high-speed rail vehicle with gauge-changeable wheelsets, wheel/rail interactions and vehicle dynamics were numerically and experimentally studied within 600 km/h. Matching among four treads, ...

In earlier work, a driver model incorporating sensory dynamics was identified from driving simulator experiments involving random disturbances, random target paths and linear vehicle dynamics. In t...

For railway locomotive, its motor bearing is one of the key components, which is likely to be damaged due to the intensified vibration conditions caused by the wheel-rail interaction and gear mesh....

Dimensional analysis has been very helpful in experimentation of very large or small-scale engineering systems. A good example would be experimentation on the aircrafts and ships, which was made co...

Little experimental data has been reported on the biomechanics of head collisions with drywall sections. The dynamics of head collisions with rigid structures are well documented. However, impacts with compliant, composite structures are more difficult to analyze. The study objective was to correlate the severity of a head impact with damage to the drywall. A human head analog was instrumented with a tri-axial accelerometer and a uniaxial load cell was placed along the cervical spine axis. A randomized block design of drop height and head orientation was utilized. The test results indicated a primarily linear correlation between drop height and peak head acceleration, as well as correlation between drop height and the geometry of the indentation to the drywall. Head posture had little influence on wall damage, however, head extension resulted in a stiffer head-spine complex compared to a flexed posture. A two-factor ANOVA determined a statistically significant correlation between damage severity and impact velocity. The results obtained can be used by accident reconstructionists to approximate the impact severity of a head impacting drywall. The study data are limited to drywall sections of known, similar geometry, and does not apply to scenarios with a support beam directly beneath the drywall. Further studies are needed to investigate additional head postures.

The friction draft gear with hysteresis characteristics is one of the typical nonlinear elements in longitudinal train dynamics (LTD). Due to the nonlinear hysteresis of friction damping, the disco...

The high-speed train needs excellent curve-passing performance, reducing wheel/rail force and wear, and sufficient hunting stability. According to the mechanism of self-steering radial bogie, the I...

This study deals with drifting as one of the most important nonlinearities in vehicle dynamics. A four-wheel vehicle model is used to calculate the equilibria in planar motion, numerically, by intr...

This paper presents a novel, non-iterative, general formulation for the transient analysis of interacting elastodynamic systems in contact that may exhibit relative motion with respect to each othe...

In this paper, modelling methods are developed to achieve dynamics exploration for the vehicle–track system and its substructures. First, a coupled model, with the satisfaction of wheel–rail displa...

The roll centre (RC) is a core parameter for vehicle lateral dynamics and control, which can be obtained via suspension geometry configuration or suspension kinematics and compliance (K&C) test. Ho...

In this paper, a coupling longitudinal-vertical dynamic model of a wheeled vehicle under off-road conditions is established. In the present model, the vehicle’s travelling velocity changes as the v...

The dynamic performance of a high-speed railway vehicle operating in low-temperature environments was studied through simulations using a stochastic, parameter-based, dynamic model. This model cons...

This paper presents a novel alternate multibody model for a tracked vehicle by replacing the tracks with a set of imaginary wheels. A planar multibody model with imaginary wheels replacing tracks i...

In this chapter, the inverse dynamics of hexapods with fixed-length legs is analyzed using the natural orthogonal complement method, with considering the mass of the moving platform and those of the legs. A complete kinematics model is developed, which leads to an explicit expression for the twist-mapping matrix. Based on that, the inverse dynamics equations are derived that can be used to compute the required applied actuator forces for the given movement of the moving platform. The developed method has been implemented and demonstrated by simulation. Successively, the static balancing of hexapods is addressed. The expression of the global center of mass is derived, based on which a set of static balancing equations has been obtained. It is shown that this type of parallel mechanism cannot be statically balanced by counterweights because prismatic joints do not have a fixed point to pivot as revolute joints. A new design is proposed to connect the centre of the moving platform to that of the fixed platform by a pantograph. The conditions for static balancing are derived. This mechanism is able to release the actuated joints from the weight of the moving legs for any configurations of the robot. In the future research the leg inertia will be include for modeling the dynamics of the hexapod for high-speed applications.

In multi-body dynamics, we model a non-conformal wheel/rail contact at one centre point since this contact is flat and Hertzian. However, the quasi-conformal contact requires more points si...

High-speed electric multiple units (EMUs) have been popularised rapidly all around the world and have become a major transportation method. Increases in running velocity and wheel-rail deterioratio...

It is well known that wheel wear degrades the dynamic performance of the rail vehicles, especially in regard to the issue customarily known as ‘running stability’ and resulting in the evaluation of...

The fundamentals of mechanical system dynamics were established before the beginning of the industrial era [...]

The purpose of this book is to provide an overview of regenerative medicine and fluid mechanics principles for the management of clinically diseased blood vessels. Authors discuss tissue engineering aspects and computational fluid mechanical principles, and how they can be used to understand the state of blood vessels in diseased conditions.

A ring model for pneumatic and non-pneumatic tyres is presented. In this model, the tread is discretised by means of lumped masses, interconnected by curved Timoshenko beams, ideally assumed massless and unloaded, and linked to the rim by spring-damper elements taking into account the sidewall properties. The equations of motion are derived via Hamilton's variational principle. The hybrid continuous-discrete approach allows to overcome the need of employing expensive methods to solve the governing equations of the systems, since they are split in two different sets. As a result, a closed-form solution for the displacement field of each beams can be provided. A qualitative analysis is carried out for different values of the elastic modulus of the tread. Results for both the normal and the tangential interactions are coherent with the physical behaviour of the real tyre. Finally, the model is validated and compared to already existing ones, showing the best overall agreement with experimental data.

This paper illustrates the potential of a gyroscopic stabiliser for the stabilisation of single-track vehicles, at low and high speed as well as during braking. Alternative systems are considered, including single and twin counter-rotating gyroscopes, spinning and precessing with respect to different axes, either freely (passive stabilisers) or in a controlled way (active stabilisers). A suitable mathematical model has been developed and stability has been investigated both by eigenvalue calculation and time domain simulations. It has been found that the most effective configuration is one where the gyroscope(s) spin with respect to an axis parallel to the wheels' spin axis and swing with respect to the vehicle yaw axis. Passive systems may effectively stabilise both weave and wobble at medium and high speed, but cannot stabilise the vehicle at low and zero speed. On the contrary, actively controlled gyroscopes are capable of stabilising the vehicle in its whole range of operating speed, as well as during braking. The alteration of the original vehicle handling characteristics is negligible when active counter-rotating gyroscopes are used, and still acceptable if a single gyroscope is adopted instead.

A number of vehicle-to-vehicle accidents occur as a result of significant differentials in speed and lane changes between traffic in laterally offset lane positions. These analyses can include many scenarios. One typical scenario is the merging of an articulated commercial vehicle from a roadway shoulder or on-ramp into a travel lane at a relatively low speed compared to the posted speed limit and/or actual travel speed of established lane traffic. Collisions arising during such events often involve less than full engagement between the vehicles and are complicated by the extended length (20 meters (m) (65.6 feet (ft)) or more) of most combination units and its effect on the time and distance it takes the unit to transition from one lane to another. Vehicle dynamics is used to analyze and understand the lane change dynamics in order to assess causes of accidents, as well as aide engineers in creating safeguards to avoid such accidents. A review of currently available analytical models finds that most are based on an analysis of a single-point object or a standard, non-articulated passenger vehicle. Additionally, many of these models consider either a constant lateral acceleration profile or a half-sine acceleration profile with specified peak lateral acceleration resulting in a constant lane change time regardless of vehicle longitudinal speed. When considering the actual lane change dynamics of a tractor-trailer, the typically applied predictive models are limited to predicting the dynamics of a singular point on the tractor-trailer during the lane change as opposed to more specific dynamics of the tractor and trailer combined effect. Testing in this study was completed using a conventional truck-tractor with sleeper berth, coupled to an unloaded 40-foot trailer chassis with a container. A total of 23 tests were completed, including (a) constant speed maneuvers for travel speeds ranging from 8.0 to 67.6 kilometers per hour (kph) (5.0 to 42.0 miles per hour (mph)) and (b) continuously accelerating travel speeds with lane changes initiated at 10.5 to 27.4 kph (6.5 to 17.0 mph). Two-dimensional time dependent tracking of the corners (tractor front left and right, trailer rear left and right) of the vehicle was documented and an imaging of the Detroit Diesel engine electronic control module (ECM) was collected after each test. Results of this study show that above speed ranges of 48 to 56 kph (30–35 mph), the timing involved in a constant-speed lane change maneuver tends to converge toward a constant; however, at lower speeds a clear inverse relation exists between speed and lane change timing. Empirical relationships were developed to more accurately predict the lane change dynamics of multiple points and the overall profile of an articulated commercial vehicle. Overall, this study provides data and relationships for consideration in lane change dynamics as well as the ability to distinguish timing of when a tractor-trailer would become perceivable versus its position in the roadway.

Phase portraits provide control system designers strong graphical insight into nonlinear system dynamics. These plots readily display vehicle stability properties and map equilibrium point location...

In order to enhance the flight envelope of Unmanned Air Vehicles (UAVs), there have been efforts to combine the excellent hover capabilities of rotorcraft with the endurance and speed performance of fixed-wing aircraft. Such efforts lead to a type of agile aircraft that can perform hover coupled with efficient flight during forward cruise. An inherent problem for such vehicles is the transition maneuver between forward flight and hover, which usually exhibits significant altitude variation, long transition time, large control effort, high thrust-to-weight ratio and loss of partial control. These characteristics are undesirable and reduce the maneuver potential of the vehicle in tight spaces. Moreover, the underlying flight dynamic characteristics of convertible platforms are still not fully explored. To mitigate the problems associated with the transition maneuvers above, this work proposes the use of variable-incidence wing, where the angle of incidence of the wing with reference to the fuselage of the aircraft can be controlled during flight. This phenomenon is also referred as “aerodynamic vectoring” as the changing of the wing-incidence changes significantly the direction of the resultant aerodynamic force. A feasibility study of the usefulness of the variable-incidence wing scheme is conducted in comparison to a conventional fixed-wing platform. The study is focusing longitudinal motion only. The lateral-directional motion is considered to be de-coupled and is out of the scope of the study. Two kind of transition maneuvers are discussed in the thesis: Steady and Unsteady transition maneuvers. Steady transition maneuvers refer to the category in which the aircraft can sustain flight with certain pitch attitude between hover and cruise. In such transitions the aircraft can be considered to be at trim during the maneuver. Unsteady transition maneuvers refer to fast aerobatic/agile transition maneuvers between hover and cruise. In such maneuvers, the aircraft may not be in trimmed conditions between its initial and final desired states. For the analysis, the aerodynamic forces and moments database is developed over the whole maneuver range using wind-tunnel-testing. For the steady transition case, the advantages of the variable-incidence wing feature are found, however eigenvalue analysis reveals that the dynamics may have some peculiarities. For this reason, further nonlinear dynamic analysis is carried out. Specifically, Multiple Time Scales (MTS) method in conjunction with bifurcation theory is used to uncover the peculiar system behavior and to understand the steady transition dynamics further. DOCTOR OF PHILOSOPHY (MAE)

210 p. Adhesion of cells to biomaterials or extracellular matrix (ECM) is a fundamental process in tissue engineering devices and biotechnological process, as well as in organogenesis and tissue maintenance. Anchorage-dependent cells adhering on surface modified with adhesive ligands will spread and undergoes cytoskeleton rearrangement. In turn, the cellular phenotypes of adherent cells on biomaterials are directly correlated with the biophysical responses of cells. However, the lack of integrated bio-analytics for probing the cell-substrate interface poses significant obstacles in the engineering analysis of cells on biomaterial or ECM surface. Based on the principle of confocal reflectance interference contrast microscopy (C-RICM), our group has successfully determined several key biophysical/biomechanical parameters of cells on model ECM. In this thesis, I apply the unique biophysical approaches on the elucidation of the effect of GFP-actin expression, Hepatitis B virus and cytoskeleton-targeting drugs on the biophysical behavior of HepG2 cells on a model ECM. DOCTOR OF PHILOSOPHY (MAE)

This thesis is dedicated to solve the adaptive control problems of robot in the presence of all uncertainties in the kinematics, manipulator dynamics and actuator dynamics. The main contribution of the thesis is that a novel adaptive regressor design method is proposed which enables the adaptation of different kinds of uncertainties simultaneously during the control process. Based on the novel regressor design, adaptive control methods have been proposed for regulation and tracking control of robot with uncertain kinematics, manipulator and actuator dynamics. These approaches constitute the first results in the research area of robot control to deal with both kinematic and actuator dynamic uncertainties. Through Lyapunov analysis, the stability of the closed-loop systems are shown to be guaranteed and the sufficient conditions to be satisfied are explicitly presented. The proposed control schemes have all been examined through simulation studies to confirm their effectiveness in dealing with the kinematic and dynamic uncertainties. Experiments were also conducted based on a vertical two-link robot driven by motors with current amplifiers. DOCTOR OF PHILOSOPHY (EEE)

Failure mode and effects analysis are performed for a dual levelling valve pneumatic suspension to determine the effect of suspension failure on tractor–semi-trailer dynamics, using a detailed model of suspension pneumatics coupled with a truck dynamic model. A key element of failure analysis in suspensions with one or two levelling valves is determining the effect on the vehicle body roll when one or more failures occur. The failure modes considered are mainly the suspension pneumatic components, including clogged levelling valve, bent control rod, disabled lever arm, and punctured or leaking connectors and pipes. The pneumatic suspension is modelled in AMESim, with critical parameters established through component testing. Upon validating the AMESim component model experimentally, the pneumatic suspension model is integrated into TruckSim for studying the consequences of suspension failure on truck dynamics. The simulation results indicate that the second levelling valve in a dual-valve arrangement brings a certain amount of failure redundancy to the system, in the sense that when one side fails, the other side can compensate for the failure. Equipping the trailer with dual levelling valves brings an additional stabilising effect to the vehicle in the event of tractor suspension failure. Accepted version

Wheel flat is one kind of railway train wheelset defects. It has great influence on wheel/rail dynamics and damages. In most of the presented studies, wheel/rail impact velocity or rolling radius v...

The dynamics of vehicles with pneumatic tyres are well-known to be non-holonomic, nonlinear, and subject to state bounds in order to remain on defined roadways. As such, it can be challenging to ap...

The severe shaking due to wind speed variation in high-speed trains has a negative impact on driving safety and riding comfort. It is difficult to solve this problem by directly applying civil engi...

A quadruple discrete element method (QDEM) was developed for viscoelastic multi-body dynamics. The sleeper motion modeled using QDEM was coupled with the rail motion modeled using a finite element method (FEM). The traffic impact response of a ballast particle and a sleeper was analyzed. The three-dimensional spatial distribution of ballast particle displacement was clearly revealed. Moreover, the ballast layer absorbed the low frequency vibration of the sleeper more effectively than its high frequency vibration. This study suggests that the proposed QDEM-FEM can provide greater insight into the impact response of ballasted railway tracks.

A parallel architecture was recently proposed to generate Schonflies motions. The CRRHHRRC closed kinematic chain offers a symmetric single-loop architecture, isostatic design, and high rotatability 1 of its gripper. This pick-and-place robot uses an innovative cylindrical drive, which is a realization of a two-degree-of-freedom cylindrical actuator. The authors report the kinematics and dynamics analysis of the above-mentioned Schonflies-motion generator, developed at McGill University’s Centre for Intelligent Machines. This analysis is intended to optimize the robot design. Validation of the mathematical model was conducted experimentally. The results reveal the accuracy of the model.

In this paper, control moment gyroscope (CMG) system is employed to suppress vibration of flexible spacecraft during attitude maneuver. Direct modal force generated by CMGs is exerted to elastic dynamics due to interaction between CMGs and flexibilities of structure. A novel control strategy based on a modal force compensator is proposed, which is simple and efficient to reduce vibration during attitude maneuver. The proposed modal force compensator avoids exciting vibration by the means of canceling out disturbance input to elastic dynamics using modal force generated by CMGs. No modal information is required in the modal force compensator. A concept named as modal force singularity is introduced and analyzed in depth. A restriction on gimbal angles is developed to avoid modal force singularity. Subsequently, a steering logic based on pseudo-inverse is proposed to allocate modal force commands without introducing force errors. Numerical simulations are presented to show the effectiveness of the proposed approaches.

In this study we will estimate the region of attraction (RoA) of the lateral dynamics of a nonlinear single-track vehicle model. The tyre forces are approximated using rational functions that are s...

As more wire ropes with complex construction are used in the hoisting system of a crane, it becomes more necessary to predict the risks of the hoisting operation. Especially the wire rope, dynamic analysis is required to manage the potential risk in advance. Thus, in this article, a co-simulation method based on multi-body dynamics and finite element method is proposed to determine the dynamic responses of a hoisting system and wire rope. We developed a dynamic model of hoisting system based on ADAMS/Cable to formulate the time history response of dynamic force on wire rope, which could be used as the loading condition in the posterior finite element model. A three-dimensional geometric model for the multi-layered strands wire rope with a construction of 1+7+7 / 7+14 wires is implemented in the finite element analysis software ABAQUS, and both static and dynamic analyses are presented. The static analysis result of force–strain relation is compared with several experiment data, and the finite element model is proved accurate and reliable. In the latter case, the force–time curves obtained by dynamic model are imported to finite element model as loading condition to accomplish dynamic analysis. The co-simulation results of hoisting wire rope’s behavior subjected to dynamic loading during the hoisting process are carried out and discussed. The stress distribution and stress spectrum of wire rope are obtained, and the results show that the most dangerous regions are the lateral side of wire rope, especially the contact area of two wires in strands.

The objective of this paper is to establish a detumbling strategy and a coordination control scheme for a kinematically redundant space manipulator post-grasping a rotational satellite. First, the dynamics of the kinematically redundant space robot after grasping the target is presented, which lays the foundation for the coordination controller design. Subsequently, optimal detumbling and motion planning strategy for the post-capture phase is proposed based on the quartic Bezier curves and adaptive differential evolution (DE) algorithm subject to the specific constraints. Both detumbling time and control torques are taken into account for the generation of the optimal detumbling strategy. Furthermore, a coordination control scheme is presented to track the designed reference path while regulating the attitude of the chaser to a desired value, which successfully dumps the initial angular velocity of the rotational satellite and controls the base attitude synchronously. Simulation results are presented for detumbling a target with rotational motion using a 7 degree-of-freedom (DOF) redundant space manipulator, which demonstrates the effectiveness of the proposed method.

The effect of engine spin direction on the dynamics of powered two wheelers is investigated in terms of steady-state points (equilibria), vibration modes (stability), manoeuvre time (performance/manoeuvrability) and handling. The goal is to assess and quantify the advantage sometimes claimed for the ‘counter-rotating’ engine configuration, where the engine spins in the opposite direction with respect to wheels, against the ‘conventional’ configuration, where the engine spins in the same direction of wheels.

When using friction gripping device with a screw drive to move designs from wood there is relaxation of tightening force of the screw with time due to rheological characteristics of wood. Weakening of tightening leads to a reduction of friction forces, holding the floating structure, which can lead to failure and drop of structure. To ensure reliable holding of wooden construction by gripping device within the specified time, prior increase in torque taking into account dynamics subsequent weakening is required. The article presents description of experimental setup to study the rate of weakening of the torque of the screw clamp and development of elastic deformation of samples of wood and plywood of different thickness with clamps of different hardness. Dependence of elastic strain and associated weakening of tightening force from time which samples stay under load, is revealed. The dependence has general nature for all the samples of wood and derivative materials. Regression analysis of the data and graphs of weakening the tightness of the clamps and development of elastic deformations is performed for each experiment. It is established that approximation to exponential function reflects the dependence of attenuation of torque settings on time in the interval up to 24 hours more accurately, than exponential function. To identify factors influencing the rate of weakening of the torque, regression analysis is made. The dependence of the rate of weakening of the torque by on stiffness of the clamp, thickness of wooden construction in the place of installation of gripping device and of the modulus of elasticity of wood is revealed. With the increase in rigidity of clamp and size of cross section of structure, weakening speed increases. Method of determining the rate of increase in force of pre-tightening of friction gripping device with screw drive to move wooden structures is suggested.

This paper presents a new mathematical model of 4 degrees of freedom of links to qualitatively describe the dynamic behavior of the front structure of an excavator. In the model, the effects of couple of forces as new additional effects are involved. The exact forms and solutions for position-varying moments of inertia used in this model are presented. A topologic structure is used for the kinematic analysis of the body frame. The numerical results show that the new additional effects can change the angular kinetic energy of all links to a significant degree when the upper structure swings. The results suggest that the new additional effects should be taken into account for analysis of excavator dynamics.