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Number of results: 5
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Abstract

The authors present the results of experimental rig study on resistance forces in a rack and pinion steering system without power assistance of a small car with MacPherson front suspension. The influence of a harmonic steering angle excitation, with frequency ranging from I to 3 Hz, and different wheel load conditions on self-returnability, sensitivity, and friction forces in the steering system is studied. These characteristics are responsible for the car directional stability at high-speed of cruising or during braking maneuver, and influence comfort, effort, and good feeling of the car driver. On the basis of experimental results, some parameters (equivalent moment of friction forces and stiffness coefficients) of a simplified model are estimated for different excitations and load conditions.
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Authors and Affiliations

Józef Knapczyk
Michał Maniowski
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Abstract

The paper presents a method for dimensional synthesis of a five-rod guiding mechanism for the front wheels of a car. The goal is to find some unknown coordinates of joint centers of three suspension rods on the basis of given input data describing selected coordinates of other points, rods lengths and desired suspension characteristics for jounce-rebound and steering displacements. The synthesis problem is formulated as a single-criteria optimization procedure with a few substages solved in hierarchical order. The procedures for position and displacement analysis of the spatial multilink mechanism and for determination of the screw axes are also described. A numerical example for the AUDI A4 front ax.le is given.
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Authors and Affiliations

Józef Knapczyk
Michał Maniowski
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Abstract

The paper presents selected methods used for estimation the unknown geometrical parameters of a spatial mechanism model, used to describe the position and orientation of the end-effector, for example the coordinates of the center points of spherical joints, link dimensions etc. These data are necessary when dealing with computer simulation of any mechanism. The parameters are estimated based on coordinate measurements of selected points, located on the real mechanism links, using a portable manipulator with serial structure composed of 6 revolute joints and a spherical probe, but other techniques of acquiring point coordinates are applicable as well. The described methods can be used in the cases of a disassembled link, an assembled mechanism and redundant data sets. The methods are characterized by accuracy and robustness in the presence of different levels of noise, stability with respect to degenerate data sets, and low computation time. Special attention is paid to the case when the wanted parameters are hard to measure directly. Numerical examples are presented dealing with 5-link mechanism used to guide front wheels of a car.

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Authors and Affiliations

Józef Knapczyk
Michał Maniowski
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Abstract

The paper presents optimization of 5-rod (5-link) suspension mechanism used in passenger cars for independent guiding of the wheels. Selected stiffness coefficients defined for five elastomeric bushings installed in joints of the suspension rods are considered as design variables. Two models with lumped parameters (i.e. elastokinematic and dynamic) of wheel-suspension-car body system are formulated to describe relationships between the design variables and the performance indexes including car active safety and ride comfort, respectively. The multi-criteria goal function is minimized using a deterministic algorithm. The suspension with optimized bushings rates fulfils desired elastokinematic criteria together with a defined dynamic criterion, describing the so-called rolling comfort. An event of car passing over short road bump is considered as dynamic conditions. The numerical example deals with an actual middle-class passenger car with 5-rod suspension at the front driven axle. Estimation of the models parameters and their verification were carried out on the basis of indoor and outdoor experiments. The proposed optimization procedure can be used to improve the suspension design or development cycle.

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Authors and Affiliations

Józef Knapczyk
Michał Maniowski
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Abstract

This paper presents an estimation method for the spatial pose and displacement parameters of multi-rod suspension mechanism, based on measurement results by using wire sensors. Some changes of position and orientation of the platform fixed to wheel knuckle cause corresponding changes of sensors’ cable lengths. The fixation points of the cable sensors are selected with the collision-free conditions taken into account. Numerical example deals with platform poses and positioning of the sensors that satisfy the measurement conditions.

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Authors and Affiliations

Marta Góra
Józef Knapczyk
Michał Maniowski

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