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An Interval Analysis and Optimization Method for Generated Axial Force of Automotive Drive Shaft Systems

South China University of Technology-Huayuan Feng, Subhash Rakheja
  • Technical Paper
  • 2020-01-0918
To be published on 2020-04-14 by SAE International in United States
To study the generated axial force (GAF) of the drive shaft system more accurately and effectively, this paper introduces the interval uncertainty into the research focusing on the GAF. Firstly, an interval uncertainty model for calculating the GAF is proposed based on the Chebyshev polynomials and an analytical model of the GAF. The input torque, the articulation angle, the rotation angle of the drive shaft system, the pitch circle radius (PCR) of the tripod joint and the friction coefficient are regarded as interval variables. Secondly, the upper and lower bounds of the proposed GAF model under interval uncertainty parameters are calculated quickly with the vertex method. Then the interval uncertainty optimization of the GAF under uncertainty parameters is performed. The upper bound of the response interval of the GAF is taken as the optimization object. Finally, the proposed model is verified by experiments, while the interval uncertainty analysis and optimization of the GAF are carried out through a numerical example.
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A Control Strategy to Reduce Torque Oscillation of the Electric Power Steering System

Concordia University Montreal-Subhash Rakheja
South China University of Technology-Duo Fu, Wen-Jun Yan, Wen-Bin Shangguan
Published 2019-06-05 by SAE International in United States
This paper proposes a new evaluation method of analyzing stability and design of a controller for an electric power steering (EPS) system. The main purpose of the EPS system’s control design is to ensure a comfortable driving experience of drivers, which mainly depends on the assist torque map. However, the high level of assist gain and its nonlinearity may cause oscillation, divergence and instability to the steering systems. Therefore, an EPS system needs to have an extra stability controller to eliminate the side effect of assist gain on system stability and attenuate the unpleasant vibration. In this paper, an accurate theoretical model is built and the method for evaluating system quality are suggested. The bench tests and vehicle experiments are carried out to verify the theoretical analysis. The evaluation method proposed in this paper can not only guide the design of controller parameters, but also evaluate the control effect while the performance of several controllers are all excellent.
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Effects of Entrapped Gas within the Fluid on the Stiffness and Damping Characteristics of a Hydro-Pneumatic Suspension Strut

SAE International Journal of Commercial Vehicles

Concordia University Montreal-Yuming Yin, Subhash Rakheja
IRSST-P-E. Boileau
  • Journal Article
  • 2017-01-0411
Published 2017-03-28 by SAE International in United States
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 effective gas pressure, which are generally neglected. The pseudo-static and dynamic properties of the HPS strut were investigated experimentally and analytically. Laboratory tests were conducted to measure responses in terms of total force and fluid pressures within each chamber under harmonic excitations and nearly steady temperature. The measured data revealed gradual entrapment of gas in the hydraulic fluid until the mean pressure saturated at about 84% of the initial pressure, suggesting considerably reduced effective bulk modulus and density of the hydraulic fluid. An analytical model of the HPS strut was formulated considering polytropic change in the gas state and increased fluid compressibility due to entrapped air. Both the measured data and the model results showed progressively hardening stiffness…
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Yaw Stability Enhancement of Articulated Commercial Vehicles via Gain-Scheduling Optimal Control Approach

SAE International Journal of Commercial Vehicles

Concordia University Montreal-Bin Li, Subhash Rakheja
  • Journal Article
  • 2017-01-0437
Published 2017-03-28 by SAE International in United States
In this paper, a gain-scheduling optimal control approach is proposed to enhance yaw stability of articulated commercial vehicles through active braking of the proper wheel(s). For this purpose, an optimal feedback control is used to design a family of yaw moment controllers considering a broad range of vehicle velocities. The yaw moment controller is designed such that the instantaneous tractor yaw rate and articulation angle responses are forced to track the target values at each specific vehicle velocity. A gain scheduling mechanism is subsequently constructed via interpolations among the controllers. Furthermore, yaw moments derived from the proposed controller are realized by braking torque distribution among the appropriate wheels. The effectiveness of the proposed yaw stability control scheme is evaluated through software-in-the-loop (SIL) co-simulations involving Matlab/Simulink and TruckSim under lane change maneuvers. Simulation results demonstrate that the proposed gain scheduling optimal controllers can yield enhanced yaw stability of articulated commercial vehicles by the updating of control gains with the change of vehicle velocity.
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Analysis of a Flow Volume Regulated Frame Steering System and Experimental Verifications

Concordia University-Yuming Yin, Subhash Rakheja
IRSST Montreal-P. E. Boileau
Published 2015-09-29 by SAE International in United States
The articulated frame steering (AFS) systems are widely implemented in construction, forestry and mining vehicles to achieve enhanced maneuverability and traction performances. The kinematic and dynamic performances of articulated steered vehicles are strongly influenced by properties of the frame steering system. In this paper, a flow volume regulated frame steering system is described and analytically modelled. The analytical model of the steering system is formulated in conjunction with yaw-plane model of a 35 tonnes mining vehicle to investigate steady as well as transient responses of the steering system and the vehicle. A field test program was undertaken to measure responses of the steering system and the vehicle under nearly constant speed turning as well as path-change maneuvers. The validity of the vehicle and the steering system model is demonstrated on the basis of the measured data in terms of steering wheel angle, articulation angle, hydraulic struts pressure, struts displacements and vehicle yaw rate. The results revealed reasonably good agreements between the measured and model responses under the maneuvers considered. The model could thus serve as…
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Jackknifing Prevention of Tractor-Semitrailer Combination Using Active Braking Control

Concordia University-Bin Li, Subhash Rakheja
Published 2015-09-29 by SAE International in United States
Vehicle jackknifing is generally associated with the loss of yaw stability, and is one of the most common cause of serious traffic accidents involving tractor-semitrailer combinations. In this paper, an active braking control strategy is proposed for jackknifing prevention of a tractor-semitrailer combination on a low friction road. The proposed control strategy is realized via upper-level and lower-level control structures considering braking of both the units. In the upper-level control, the required corrective yaw moments for tractor and semitrailer are generated using a PID controller aiming to reduce errors between the actual yaw rates of tractor-semitrailer and the target yaw rates deduced from a reference model. The corrective yaw moments are achieved through brake torque distribution among the tractor and semitrailer axle wheels in the lower-level control. The effectiveness of the proposed jackknifing prevention control is evaluated in a co-simulation environment involving Matlab/Simulink and TruckSim under two different maneuvers on a slippery road surface. Simulation results show that the proposed control approach is effective in jackknifing prevention of the tractor-semitrailer combinations under high speed maneuvers…
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Relative Performance Analyses of Independent Front Axle Suspensions for a Heavy-Duty Mining Truck

SAE International Journal of Commercial Vehicles

Concordia University Montreal-Yiting Kang, Subhash Rakheja
University of Science & Technology Beijing-Wenming Zhang
  • Journal Article
  • 2014-01-2320
Published 2014-09-30 by SAE International in United States
A range of axle suspensions, comprising hydro-pneumatic struts and diverse linkage configurations, have evolved in recent years for large size mining trucks to achieve improved ride and higher operating speeds. This paper presents a comprehensive analysis of different independent front suspension linkages that have been implemented in various off-road vehicles, including a composite linkage (CL), a candle (CA), a trailing arm (TA), and a double Wishbone (DW) suspension applied to a 190 tons mining truck. Four different suspension linkages are modeled in MapleSim platform to evaluate their kinematic properties. The relative kinematic properties of the suspensions are evaluated in terms of variations in the kingpin inclination, caster, camber, toe-in and horizontal wheel center displacements considering the motion of a hydro-pneumatic strut. The results revealed the CL and DW suspensions yield superior kinematic response characteristics compared to the CA and TA suspensions. Toe-in and horizontal wheel center displacements of the CA and TA vary significantly, which could strongly affect the vehicle handling performance and cause greater tire wear. The CL and DW suspensions may thus be…
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Effect of Terrain Roughness on the Roll and Yaw Directional Stability of an Articulated Frame Steer Vehicle

SAE International Journal of Commercial Vehicles

Concordia University Montreal-Alireza Pazooki, Subhash Rakheja
Lancaster University-Dongpu Cao
  • Journal Article
  • 2013-01-2366
Published 2013-09-24 by SAE International in United States
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 vertical and lateral tire forces. It may thus be desirable to assess the dynamic safety of ASVs in terms of their directional control and stability limits while operating on different terrains. The effects of terrain roughness on the directional stability limits of an ASV are investigated through simulations of a comprehensive three-dimensional model of the vehicle with and without a rear axle suspension. The model incorporates a torsio-elastic rear axle suspension, a kineto-dynamic model of the frame steering struts and equivalent random profiles of different undeformable terrains together with coherence between the two tracks profiles. The simulations are performed to determine the stability limits of the ASV models while operating on different terrains, namely: a perfectly smooth surface, plowed field, pasture, gravel road, and the MVEE…
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Characterization of Driver Steering Control of Articulated Freight Vehicles Based on a Two-Stage Preview Strategy

SAE International Journal of Commercial Vehicles

Concordia University Montreal-Siavash Taheri, Subhash Rakheja, Henry Hong
  • Journal Article
  • 2013-01-2388
Published 2013-09-24 by SAE International in United States
A two-stage preview strategy is proposed to characterize steering control properties of commercial vehicle drivers. The strategy includes a near and a far preview points to describe the driver control of lateral path deviation and vehicle orientation. A human driver model comprising path error compensation and dynamic motions of the limb is subsequently formulated and integrated to a yaw-plane model of an articulated vehicle. The coupled driver-vehicle model is analyzed under an evasive steering maneuver to identify limiting values of the driver control parameters through minimization of a generalized performance index comprising driver's steering effort, path deviations and selected vehicle states. The performance index is further analyzed to identify relative contributions of different sensory feedbacks, which may provide important guidance for designs of driver-assist systems (DAS). The results show that the proposed model structure could serve as an effective tool to identify human control limits and to determine the most effective motion feedback cues. The results further imply that lateral position and heading angle of the lead unit are the most essential sensory cues to…
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Analysis of Ride Vibration Environment of Soil Compactors

SAE International Journal of Commercial Vehicles

Concordia University-Subhash Rakheja, Alireza Pazooki, Dainius Juras
IRSST-Pierre Marcotte PhD
  • Journal Article
  • 2010-01-2022
Published 2010-10-05 by SAE International in United States
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 tires. The analytical model was formulated for the transit mode of operation at a constant forward speed on undeformable surfaces with the roller vibrator off. Field measurements were conducted to characterize the ride vibration environments during the transit mode of operation. The measured data revealed significant magnitudes of whole-body vibration of the operator-station along the vertical, lateral, pitch and roll-axes. The model results revealed reasonably good agreements with ranges of the measured vibration data. The ride dynamic responses of the soil compactor model were subsequently analyzed to study its whole-body vibration environment while operating on undeformable random terrain surfaces. Parametric sensitivity analyses were performed to study influences of different design parameters on the whole body vibration responses, which included the drum and cab vibration isolators, vertical seat…
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