Input shaping control with reentry commands of prescribed duration

Control of flexible mechanical structures often deals with the problem of unwanted vibration. The input shaping is a feedforward method based on modification of the input signal so that the output performs the demanded behaviour. The presented approach is based on a finite-time Laplace transform. It leads to no-vibration control signal without any limitations on its time duration because it is not strictly connected to the system resonant frequency. This idea used for synthesis of control input is extended to design of dynamical shaper with reentry property that transform an arbitrary input signal to the signal that cause no vibration. All these theoretical tasks are supported by the results of simulation experiments

System model reduction for MBS optimization

A disadvantage of optimization of flexible multibody systems (MBS) is a computing time, mainly for large systems, especially designed by FEM. The computing time rises with the complexity of the model significantly. A reduction techniques allow decreasing of degrees of freedom and it contributes to the reduction of the computing time. These techniques can be used for the reduction from thousands and more degrees of freedom to tens, but some limits exist. A reduction degree (ratio between number of DOFs before and after the reduction) is the most important feature because it predicts the final accuracy of the model. The next one is the selection of master and slave degrees of freedom that play an important role in connecting all bodies together within the MBS (e.g. by joints). There are many reduction methods, but they differ in available accuracy, speed, efficiency and suitability for the same reduction degree. A dimension of the original system is decisive for the reduction method suitability, many methods require an inversion matrix from the part of the stiffness matrix. The inversion matrix are than largeand the computing time grows up. This paper deals with the reduction techniques, their disadvantages, suitability and applicability

Synthesis of dexterity measure of mechanisms by evolution of dissipative system

The paper deals with the new approach of solving traditional kinematical synthesis of mechanisms. The kinematical synthesis is reformulated as nonlinear dynamical problem. All searched parameters of the mechanism are in this dynamical dissipative system introduced as time-varying during motion of mechanism’s dimension iteration. The synthesis process is realized as the time evolution of such system. One of the most important objectives of the machine synthesis is the dexterity measure. The new approach is applied to optimization of this property

Study of Concepts of Parallel Kinematics Machines for Advanced Manufacturing

This paper deals with possible new concepts for machine tools based on parallel kinematics for advanced manufacturing. Parallel kinematics machines (PKM) enable the mechanical properties of manufacturing machines to be improved. This has been proven by several new machine tool concepts. However, this potential can be and must be increased by applying the principle of redundant actuation. This paper deals with the extension of the concepts of redundantly actuated parallel kinematics structures for five-sided five-axis machine tools and for a free-forming sheet metal forming machine. The design principles of previous successful PKMs are summarized and new concepts are proposed. The most important requirement criteria are summarized. The proposed concepts are qualitatively and initially quantitatively evaluated according to these criteria.

Dynamic Bridge Response for a Bridge-friendly Truck

A truck with controlled semi-active suspensions traversing a bridge is examined for benefits to the bridge structure. The original concept of a road-friendly truck was extended to a bridge-friendly vehicle, using the same optimization tools. A half-car model with two independently driven axles is coupled with simply supported bridges (beam, slab model) with the span range from 5 m to 50 m. Surface profile of the bridge deck is either stochastic or in the shape of a bump or a pot in the mid-span. Numerical integration in the MATLAB/SIMULINK environment solves coupled dynamic equations of motion with optimized truck suspensions. The rear axle generates the prevailing load and to a great extent determines the bridge response. A significant decrease in contact road-tire forces is observed and the mid-span bridge deflections are on average smaller, when compared to commercial passive suspensions.

A Complete Parametric Solutions of Eigenstructure Assignment by State-Derivative Feedback for Linear Control Systems

In this paper we introduce a complete parametric approach for solving the problem of eigenstructure assignment via state-derivative feedback for linear systems. This problem is always solvable for any controllable systems iff the open-loop system matrix is nonsingular. In this work, two parametric solutions to the feedback gain matrix are introduced that describe the available degrees of freedom offered by the state-derivative feedback in selecting the associated eigenvectors from an admissible class. These freedoms can be utilized to improve robustness of the closed-loop system. Accordingly, the sensitivity of the assigned eigenvalues to perturbations in the system and gain matrix is minimized. Numerical examples are included to show the effectiveness of the proposed approach.

Design and Properties of Octaslide Redundant Parallel Kinematics

This paper describes the conceptual design process of OCTASLIDE redundant parallel kinematics for a machine tool. Redundantly actuated parallel kinematics is a recently developed new concept for machine tools. It enables all mechanical properties of machine tools to be improved several times simultaneously. This is particularly demonstrated on the design of the OCTASLIDE. This is a concept of a five-axis machine tool centre. The paper describes the critical initial design phases and the accessible mechanical properties. The design process has follow the newly developed design methodology for parallel kinematics machines

Eigenstructure Assignment by State-derivative and Partial Output-derivative Feedback for Linear Time-invariant Control Systems

This paper introduces a parametric approach for solving the problem of eigenstructure assignment via state-derivative feedback for linear control time-invariant systems. This problem is always solvable for any controllable systems if the open-loop system matrix is nonsingular. In this work, the parametric solution to the feedback gain matrix is introduced that describes the available degrees of freedom offered by the state-derivative feedback in selecting the associated eigenvectors from an admissible class. These freedoms can be utilized to improve the robustness of the closed-loop system. Finally, the eigenstructure assignment problem via partial output-derivative feedback is introduced. Numerical examples are included to show the effectiveness of the proposed approach

Effect of rubber powder from waste tyre rubbers on mechanical properties of one-component polyurethane putty

ArticleThe utilization of adhesives in technical practice is varied. Adhesives serve for a creation of strength bonds on the one hand, and on the other hand e.g. for cementing. The aim of the research is a modification of one - component polyurethane putty RPS 45 used in automotive industry to increase strength properties in an adhesive bond. An i nteraction between a filler in the form of rubber powder micro - particles and one - component polyurethane adhesive was investigated by means of SEM analysis. Sealing is a primary property of this putty. Sealing putties usually reach very small strength which can be increased by an admixture of the filler. In order to keep elastic properties, micro - particles of the rubber powder gained from tyre recycling process were used as the filler. An aspect of a loading speed of the adhesive bond is essential at the pra ctical application at which the adhesive bond can be failed in adhesive or cohesive layers. The adhesive bond can be perceived in terms of its function as a complex of three layers, i.e. an adhesive bonded material, the interaction between the adhesive and the adhesive bonded material and the adhesive layer itself. There are often states in the practices when the adhesive bonds are exposed to the loading which can be either a static or a dynamic one. That is why the research is focused not only on the evalu ation of the influence of the modification of the one - component polyurethane adhesive, but also on the influence of the loading speed of the adhesive bond. Tested speeds set on a universal testing machine Zwick/Roell Z150 were 2, 50 and 100 mm min - 1 . The r esults of mechanical tests proved a positive influence of the filler on the strength σ m higher by 42.68 ± 6.96% and the elongation at break ε b higher by 12.2 ± 20.95%. On the contrary, the stress at yield σ y was decreased

Concurrent Design of Railway Vehicles by Simulation Model Reuse

This paper describes a concurrent design approach to railway vehicle design. Current railway vehicles use many different concepts that are combined into the final design concept. The design support for such systems is based on reusing components from previous design cases. The key part of the railway vehicle design concept is its simulation model. Therefore the support is based on support for reuse of previous simulation models. The simulation models of different railway component concepts are stored using the methodology from the EU CLOCKWORK project. The new concept usually combines stored components