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KSU-3356 Tampere University of Technology KSU-3356 DESIGN OF MECHATRONICS SYSTEM LECTURE NOTES Feihu Zhao feihu.zhao@tut.fi KSU-3356 Tampere University of Technology Lecture 01 1. Phases of Design 2. Moore’s Law The complexity for minimum component costs has increased at a rate of roughly a factor of two per year; Certainly over the short term this rate can be expected to continue, if not to increase. Over the longer term, the rate of increase is a bit more uncertain, although there is no reason to believe it will not remain nearly constant for at least 10 years. 3. Ray Kurzweil’s Theory of the Technology Singularity Ray Kurzweil has suggested that the human race will soon (by the mid 21st Centry) evolve into transhumant immortal humanoid robots which will work to eventually turn the entire universe into a gigantic supercomputer. He also suggest that this supercomputer will be able to reverse entropy so that the immortal robots can live inside the supercomputer in virtual reality forever. 3.Some examples Music Media; Applying information technology at cars; Communication with computer in the past, now and in the future; etc. KSU-3356 Tampere University of Technology Lecture 02 1.New Product Development Task At the beginning of product development, a market report should be made, considering the following questions: (1) What the customer want to have; (2) What competitors can offer; (3) Where we have new thought; (4) where there is our target groups; (5) Which phase of life our other products are; (6) What advantages the new product could bring. 2. Expected Commercial Value of the Product 3. Stages (1) Skethcing Phase; (2) Outlining Phase; (3) Finishing Phase. 4. Nature of Design y=f(x) yr = Set of requirements; y= Expected system characteristics; x= Information describing the design; f= function mapping design x to system characteristics; f-1= ideal design. 5.Example of design matrix KSU-3356 Tampere University of Technology Lecture 03 1. Allometric Models, Modeling Scale Dependency 2. Linear Regression yi= axi+b+εi Estimate for coefficient a and b, in which the residual εi is minimal. 3.Allometric Models, Power Model N (1) An Allometric relationship often has the form : yi=bi x mij j j 1 N Which also can be written as: log(yi)=bi+ mij log( x j ) j 1 eg. Electrical motor, weight/power 4. Model Representation x y=y0 x0 a0 y a0 y0 x x0 a0= x0 dy y 0 dx 5.General Representation for the Multi Variable Model KSU-3356 Tampere University of Technology Lecture 04 1.Design Matrix Connect system properties to system parameters. eg. 2. Axiomatic Design Axiom1: Independence Axiom; Axiom2: Good design has low information content. eg. Aeroplane: 3. Taguchi-method (1) The object of taguchi-method is to determine the values of parameters the designer can choose so that a maxium performance will be reached with minimum distance for variation in condition and production parameters. (2) The number which appears in the matrix tells the number of the tests to be performed. Number 1 and Number 2 in the matrix represent the levels of parameters, in this case small and big values. The test result Y is the quality property of the product which an attempt is made to optimize. 4. Relationship between customer properties to computer properties eg. An electrical motorcycle In the system characteristics such as: Range; Acceleration; Maxium Speed; Operational Cost; Final Cost. KSU-3356 Tampere University of Technology Lecture 05 1. Sensitivity Analysis y=f(x)-----Nonlinear Function y0+Δy=f(x0)+JΔx Δy=JΔx Here, Jacobian J is also identical to the sensitivity matrix k. 2.Normalized Sensitivities kij= xi y i y i x j Result in dimensionless values in a operating point. 3. Relative Sensitivities In this way, the sum of elements in one row is one and it is easier to get an overview of the relative importance of different parameters. This is refered here as the Relative Sensitivity. 4. Aggregated Design Impact Matrix (1) Add absolute values of all sensitivities to avoid of the drawback that while adding parameters together, they will cancel each other. (2) In this way, the matrix when shown at the top level will have the same appearance regardless of how detailed the underlying system is. 5. System Characteristics Correlation (SCC) (1) Completely aligned: correlation=1;Orthogonal: correlation=0; Point in the opposite direction: correlation=-1. (2) 6. System Characteristics Dependencies(SCD) (1) SCD is used for measuring what areas can be improved without scarifying too much in other areas when setting up the requirement for designing. (2) SCDik m k j 1 0 0 ij kj k KSU-3356 Tampere University of Technology Lecture 06 1. Concept Generation (1) Black Box as a starting point: (2) Realization of functions can be distributed as a chain of sub-functions: 2. Function Means Tree Enable systematic searching of alternative concepts: KSU-3356 Tampere University of Technology Lecture 07 1. Fault Tree Analysis(FTA) Procedure of FTA: (1) Define the system of interest; (2) Define the TOP event for the analysis; (3) Define the tree top structure; (4) Expand each branch in successive levels of detail; (5) Solve the fault tree for the combinations of events contributing to the top event; (6) Identify important dependent failure potentials and adjust the model appropriately; (7) Perform quantitative analysis.(if necessary); (8) Use the results in decision making. eg. risk of fire: 2. Reliability Calculation (1) If the system is described by the equation a=bcd (like the eg. of risk of fire), the propability of top level event can be written as: λa =λbλcλd where, λx is propability that event x will occur. (2) If the system is described by the equation: a=b+c+d (or a=-((-b)+(-c)+(-d)) where, -x is the inverse of x and hence the propability of –x is: λ-x =(1- λx); λa =1-(1-λb)(1-λc)(1-λd) eg. 3.Mean Time Between Failures(MTBF) λ Nf Ttor MTBF=1/ λ Failure rate λ express number of failures in total time. MTBF is used as a measure of reliability KSU-3356 Tampere University of Technology Lecture 08 1. Testing the Control Center of the Load Problem: How to ensure that the module software functions correctly in all situation? Control system between all kinds of softwares should be tested. And the structure of testing system is like following figure. 2. Product Modeling Several modeling approaches: (1)Graphical ’high level of abstraction’ representations; (2) Some are standardized and available in commercial software based tools; (3) Other technical modeling and simulation tools, such as: MATLAB, CAD/CAM etc. are developed. 3.Requirement Representation Processes: (1) Elicitation; (2) Analysis; (3) Specification; (4) Validation. 4. Sate Diagram How to create state diagram? (1) Find all relevant states and transitions; (2) For each state, define (a.) all possible state transitions, (b.) triggers for all transitions. 5. UML (1) Why use UML? (a) Help to reduce cost and time-to-market;(b) Help managing a complex project architecture; (c) Help to convey ideas between developers/designers/etc. (2) Take example of coffee machine: Drinker: Coins Return (Functionality) Buys a cup of coffee Extension Porter: Brew a cup of coffee Service: add substance Keep track consumption of Choose machine service KSU-3356 Tampere University of Technology