Walid Ghie

Statistical tolerance analysis using the unified Jacobian–Torsor model

This paper presents the results of ongoing research aimed at developing an integrated computer-aided tolerancing tool. A unified Jacobian–Torsor approach has been developed for deterministic (worst case) computer-aided tolerancing. The paper describes how one can use the same set of interval-based deterministic equations in a statistical context. The nature of the resulting equations lends itself to very fast computations to determine the percentage of rejected assemblies produced given some statistical distribution of the tolerances of their constituent parts. An example application is also presented to illustrate the use of the developed tool.

Statistical analysis tolerance using jacobian torsor model based on uncertainty propagation method

One risk inherent in the use of assembly components is that the behaviour of these components is discovered only at the moment an assembly is being carried out. The objective of our work is to enable designers to use known component tolerances as parameters in models that can be used to predict properties at the assembly level. In this paper we present a statistical approach to assemblability evaluation, based on tolerance and clearance propagations. This new statistical analysis method for tolerance is based on the Jacobian-Torsor model and the uncertainty measurement approach. We show how this can be accomplished by modeling the distribution of manufactured dimensions through applying a probability density function. By presenting an example we show how statistical tolerance analysis should be used in the Jacobian-Torsor model. This work is supported by previous efforts aimed at developing a new generation of computational tools for tolerance analysis and synthesis, using the Jacobian-Torsor approach. Th...

State-feedback and Linear Quadratic regulator applied to a single-link flexible manipulator

This work presents a comparative study of two different control strategies for a flexible single-link robotic manipulator. The dynamic model of the flexible manipulator involves modeling the rotational base and the flexible link as rigid bodies using the Lagranges method. The resulting system has one Degree-Of-Freedom (1 DOF). Two types of regulators are studied and discussed: the State-Feedback controller, and the Linear-Quadratic regulator (LQR). While the latter is obtained by resolving the Riccati equation, the state-feedback consists on poles placement. A simulation is performed on MATLAB (7.5.0)/SIMULINK (V7.0)®, and later on, experiments were achieved on the flexible beam Quanser module. Experimental results are presented and compared at the end of this paper.

Numerical Investigation of a First Stage of a Multistage Centrifugal Pump: Impeller, Diffuser with Return Vanes, and Casing

This paper deals with the numerical investigation of a liquid flow in a first stage of a multistage centrifugal pump consisting of an impeller, diffuser with return vanes, and casing. The continuity and Navier-Stokes equations with the turbulence model and standard wall functions were used. To improve the design of the pumps first stage, the impacts of the impeller blade height and diffuser vane height, number of impeller blades, diffuser vanes and diffuser return vanes, and wall roughness height on the performances of the first stage of a multistage centrifugal pump were analyzed. The results achieved reveal that the selected parameters affect the pump head, brake horsepower, and efficiency in a strong yet different manner. To validate the model developed, the results of the numerical simulations were compared with the experimental results from the pump manufacturer.

Tolerance Analysis Using Jacobian-Torsor Model: Statistical and Deterministic Applications

In industry, the current practice concerning geometrical specifications for mechanical parts is to include both dimensions and tolerances. The objective of these specifications is to describe a class of functionally acceptable mechanical parts that are geometrically similar. To ensure that their functionality in respected during, assembly designers have to apply tolerance analysis. A model based on either worst-case or statistical type analysis may be used. This paper explains both types using the Jacobian-Torsor unified model. For statistical tolerance analysis we consider Monte Carlo simulation and for the worst case type we consider arithmetic intervals. Although the numerical example presented is for a three-part assembly, the method used is capable of handling three-dimensional geometry.

Vibration controllability and observability of a single-link flexible manipulator

This work presents a comparative study of two different control strategies for a flexible single-link robotic manipulator. The dynamic model of the flexible manipulator involves modeling the rotational base and the flexible link as rigid bodies using Lagranges method. The resulting system has one rigid Degree-Of-Freedom (1 DOF). Two types of regulators are studied and discussed: the State-Feedback controller, and the Linear-Quadratic regulator (LQR). While the latter is obtained by resolving the Riccati equation, the state-feedback consists on poles placement. A simulation is performed on MATLAB (7.5.0)/SIMULINK (V7.0)®, and later on, experiments were achieved on the flexible beam Quanser module. Experimental results are presented and compared at the end of this paper.