scholarly journals Assessment of Risky Cornering on a Horizontal Road Curve by Improving Vehicle Suspension Performance

2021 ◽  
Vol 16 (4) ◽  
pp. 1-27
Author(s):  
Vidas Žuraulis ◽  
Vytenis Surblys
Keyword(s):  
Degrees Of Freedom ◽  
Contact Forces ◽  
Critical Parameters ◽  
Vehicle Suspension ◽  
Vehicle Stability ◽  
Stability Factor ◽  
Pavement Roughness ◽  
Driving Speed ◽  
Iso 8608 ◽  
Suspension Performance

Vehicle stability during cornering on horizontal road curves is a risky stage of travel because of additional factors acting. The main stability factor is centrifugal force, which depends on road curve sharpness and is very sensitive to driving speed usually controlled by the driver. However, the counterforce is produced at tire-road interaction, where different pavement types and states cause a wide variation of tire contact forces and vehicle stability. In the paper, the part of vehicle suspension performance while moving on a sharp horizontal road curve with different levels of pavement roughness was simulated by 14 degrees of freedom vehicle model. The model was built in MATLAB/Simulink software with available pavement roughness selection according to ISO 8608. The influence of variable suspension damping available in modern vehicles on risky cornering is analysed when a vehicle reaches the edge of the pavement with its specific roughness. Critical parameters of vehicle stability depending on road curvature, pavement roughness and driving speed are selected to assess the solutions for safe cornering.

Dynamic Analysis and Configuration Design of a Two-Component Wave-Energy Absorber

2012 ◽  
Author(s):  
Christophe Cochet ◽  
Ronald W. Yeung
Keyword(s):  
Wave Energy ◽  
Degrees Of Freedom ◽  
Outer Cylinder ◽  
Rigid Body Dynamics ◽  
Contact Forces ◽  
Energy Extraction ◽  
Energy Absorber ◽  
Compound Cylinder ◽  
Motion Study ◽  
Heave Motion

The wave-energy absorber being developed at UC Berkeley is modeled as a moored compound cylinder, with an outer cylinder sliding along a tension-tethered inner cylinder. With rigid-body dynamics, it is first shown that the surge and pitch degrees of freedom are decoupled from the heave motion. The heaving motion of the outer cylinder is analyzed and its geometric proportions (radii and drafts ratios) are optimized for wave-energy extraction. Earlier works of Yeung [1] and Chau and Yeung [2,3] are used in the present heave-motion study. The coupled surge-pitch motion can be solved and can provide the contact forces between the cylinders. The concept of capture width is used to characterize the energy extraction: its maximization leads to optimal energy extraction. The methodology presented provides the optimal geometry in terms of non-dimensional proportions of the device. It is found that a smaller radius and deeper draft for the outer cylinder will lead to a larger capture width and larger resulting motion.

Distribution of Wrench-Twist Duality in Over-Constrained Mechanisms

2003 ◽  
Vol 125 (1) ◽  
pp. 81-91 ◽  
Author(s):  
M. Fayet
Keyword(s):  
Degrees Of Freedom ◽  
Contact Forces ◽  
Simple Test ◽  
The Matrix

First, a procedure is presented in order to build the space of statically admissible wrenches. The matrix which generates them is obtained in an intrinsic way. It uses intersection of spaces for the edges (of the associated graph) and the new operation of “triangular projection” for the vertices. From this matrix, the choice of any set of indeterminable contact forces is achieved via a very simple test. This matrix allows to determine also all the possible degrees of freedom to add to the over-constrained mechanism in order to transform it into a non over-constrained one. Wrench-twist duality arises clearly in this last procedure.

Rolling Condition and Gyroscopic Moments in Curve Negotiations

2012 ◽  
Author(s):  
Ahmed A. Shabana ◽  
Martin B. Hamper ◽  
James J. O’Shea
Keyword(s):  
Coordinate System ◽  
Degrees Of Freedom ◽  
The Body ◽  
Contact Forces ◽  
Body Motion ◽  
Global Coordinate System ◽  
Gyroscopic Moment ◽  
Absolute Angular Velocity ◽  
Pure Rolling ◽  
The Stability

In vehicle system dynamics, the effect of the gyroscopic moments can be significant during curve negotiations. The absolute angular velocity of the body can be expressed as the sum of two vectors; one vector is due to the curvature of the curve, while the second vector is due to the rate of changes of the angles that define the orientation of the body with respect to a coordinate system that follows the body motion. In this paper, the configuration of the body in the global coordinate system is defined using the trajectory coordinates in order to examine the effect of the gyroscopic moments in the case of curve negotiations. These coordinates consist of arc length, two relative translations and three relative angles. The relative translations and relative angles are defined with respect to a trajectory coordinate system that follows the motion of the body on the curve. It is shown that when the yaw and roll angles relative to the trajectory coordinate system are constrained and the motion is predominantly rolling, the effect of the gyroscopic moment on the motion becomes negligible, and in the case of pure rolling and zero yaw and roll angles, the generalized gyroscopic moment associated with the system degrees of freedom becomes identically zero. The analysis presented in this investigation sheds light on the danger of using derailment criteria that are not obtained using laws of motion, and therefore, such criteria should not be used in judging the stability of railroad vehicle systems. Furthermore, The analysis presented in this paper shows that the roll moment which can have a significant effect on the wheel/rail contact forces depends on the forward velocity in the case of curve negotiations. For this reason, roller rigs that do not allow for the wheelset forward velocity cannot capture these moment components, and therefore, cannot be used in the analysis of curve negotiations. A model of a suspended railroad wheelset is used in this investigation to study the gyroscopic effect during curve negotiations.

Study of grasp-energy based optimal distribution of contact forces on a humanoid robotic hand during object grasp

Robotica ◽  
2021 ◽  
pp. 1-26
Author(s):  
Sourajit Mukherjee ◽  
Abhijit Mahapatra ◽  
Amit Kumar ◽  
Avik Chatterjee
Keyword(s):  
Optimization Algorithm ◽  
Degrees Of Freedom ◽  
Simulated Data ◽  
Performance Measure ◽  
Contact Forces ◽  
Contact Model ◽  
Robotic Hand ◽  
Net Energy ◽  
Optimal Distribution

Abstract A novel grasp optimization algorithm for minimizing the net energy utilized by a five-fingered humanoid robotic hand with twenty degrees of freedom for securing a precise grasp is presented in this study. The algorithm utilizes a compliant contact model with a nonlinear spring and damper system to compute the performance measure, called ‘Grasp Energy’. The measure, subject to constraints, has been minimized to obtain locally optimal cartesian trajectories for securing a grasp. A case study is taken to compare the analytical (applying the optimization algorithm) and the simulated data in MSC.Adams $^{^{\circledR}}$ , to prove the efficacy of the proposed formulation.

scholarly journals Simulation analysis of efficiency and stability for vehicle’s ABS control on combined steering and braking maneuvers

2019 ◽  
Vol 272 ◽  
pp. 01024 ◽  
Author(s):  
Feng YU ◽  
Jun XIE
Keyword(s):  
High Speed ◽  
Control Algorithm ◽  
Degrees Of Freedom ◽  
Simulation Analysis ◽  
Stability Control ◽  
Vehicle Stability ◽  
Slip Ratio ◽  
Braking Performance ◽  
Braking System ◽  
The Stability

Eight degrees of freedom vehicle model was established. Using the method of fuzzy control, the ABS control algorithm was designed based on slip ratio. Simulation analysis was done at speed of 15m/s, 20m/s, 25m/s under turning braking. The results show that the vehicle braking performance and vehicle stability at middle or low speed was improved by using the ABS controller, but qualitative analysis shows that phenomenon of vehicle instability was appeared at high-speed conditions. The turning braking stability under ABS controller was judged quantificationally by the stability judging formula. The results show that the requirements of stability control could not meet with only Anti-lock Braking System.

Railway Truck Response to Random Rail Irregularities

1975 ◽  
Vol 97 (3) ◽  
pp. 957-964 ◽  
Author(s):  
Neil K. Cooperrider
Keyword(s):  
High Speed ◽  
Degrees Of Freedom ◽  
Equations Of Motion ◽  
Tangential Force ◽  
Contact Forces ◽  
Guidance Force ◽  
Power Spectral ◽  
Power Spectral Densities ◽  
Rail Irregularities ◽  
Frequency Domain Techniques

This paper discusses the random response of a seven degree of freedom, passenger truck model to lateral rail irregularities. Power spectral densities and root mean square levels of component displacements and contact forces are reported. The truck model used in the study allows lateral and yaw degrees of freedom for each wheelset, and lateral, yaw and roll freedoms for the truck frame. Linear creep relations are utilized for the rail-wheel contact forces. The lateral rail irregularities enter the analysis through the creep expressions. The results described in the paper were obtained using frequency domain techniques to solve the equations of motion. The reported results demonstrate that the guidance force needed when traveling over irregular rail at high speed utilizes a significant portion of the total available tangential force between wheel and rail.

Road profile measurement using the two degrees of freedom response-type mechanism

2014 ◽  
Vol 229 (6) ◽  
pp. 1074-1087 ◽  
Author(s):  
O Kavianipour ◽  
M Montazeri-Gh ◽  
M Moazamizadeh
Keyword(s):  
Degrees Of Freedom ◽  
Suspension System ◽  
Vehicle Suspension ◽  
Profile Measurement ◽  
Response Type ◽  
Two Degrees Of Freedom ◽  
Road Profile ◽  
Measured Profile ◽  
The Time Domain ◽  
Vehicle Suspension System

This paper deals with the two degrees of freedom response-type mechanism (2 DOF RTM) designed at Iran University Science and Technology. The applications of the 2 DOF RTM are to measure the longitudinal road profile and assess the vehicle suspension system. When the 2 DOF RTM is connected to a vehicle, it is able to measure the longitudinal road profile and it is capable of assessing the vehicle suspension system while it is perched upon the exciting device. The most important part of the 2 DOF RTM is its hub planned for decreasing the vehicle movement effects on the measurement. Moreover, this paper develops a novel procedure in order to convert the measured profile from the variable speed to the constant speed. To examine the 2 DOF RTM, a profile of a road is measured by the mechanism in the time-domain, and then the highly significant roughness indices such as power spectral density (PSD) of the road unevenness, international roughness index (IRI) and present serviceability index (PSI) are estimated using the measured profile.

scholarly journals Component Mode Synthesis Using Undeformed Interface Coupling Modes to Connect Soft and Stiff Substructures

2013 ◽  
Vol 20 (1) ◽  
pp. 157-170 ◽  
Author(s):  
Eskil Lindberg ◽  
Nils-Erik Hörlin ◽  
Peter Göransson
Keyword(s):  
Degrees Of Freedom ◽  
Component Mode Synthesis ◽  
Vehicle Suspension ◽  
Synthesis Methods ◽  
Test Case ◽  
Rotation Axes ◽  
Acoustic Modelling ◽  
Stiffness Properties ◽  
Rubber Bushing ◽  
Vehicle Suspension System

Classical component mode synthesis methods for reduction are usually limited by the size and compatibility of the coupling interfaces. A component mode synthesis approach with constrained coupling interfaces is presented for vibro-acoustic modelling. The coupling interfaces are constrained to six displacement degrees of freedom. These degrees of freedom represent rigid interface translations and rotations respectively, retaining an undeformed interface shape. This formulation is proposed for structures with coupling between softer and stiffer substructures in which the displacement is chiefly governed by the stiffer substructure. Such may be the case for the rubber-bushing/linking arm assembly in a vehicle suspension system. The presented approach has the potential to significantly reduce the modelling size of such structures, compared with classical component mode synthesis which would be limited by the modelling size of the interfaces. The approach also eliminates problems of nonconforming meshes in the interfaces since only translation directions, rotation axes and the rotation point need to be common for the coupled substructures. Simulation results show that the approach can be used for modelling of systems that resemble a vehicle suspension. It is shown for a test case that adequate engineering accuracy can be achieved when the stiffness properties of the connecting parts are within the expected range of rubber connected to steel.

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