M 16888 esd ESD.J7 Goal Programming and Isoperformance March 29. 2004 Lecture 15 Olivier de Weck o Massachusetts Institute of Technology -Prof de Weck and Prof Willcox Engineering Systems Division and Dept of Aeronautics and Astronautics
1 Goal Programming and Goal Programming and Isoperformance Isoperformance March 29, 2004 Lecture 15 Olivier de Weck © Massachusetts Institute of Technology - Prof. de Weck and Prof. Willcox Engineering Systems Division and Dept. of Aeronautics and Astronautics
Mlesd Why not performance-optimal 35.9 The experience of the 1960s has shown that for military aircraft the cost of the final increment of performance usually is excessive in terms of other characteristics and that the overall system must be optimized, not just performance Ref: Current State of the art of Multidisciplinary design Optimization (MDO TC)-AlAA White Paper, Jan 15, 1991 TRW Experience Industry designs not for optimal performance, but according to targets specified by a requirements document or contract -thus, optimize design for a set of GOALs o Massachusetts Institute of Technology -Prof de Weck and Prof Willcox Engineering Systems Division and Dept of Aeronautics and Astronautics
2 Why not performance Why not performance-optimal ? optimal ? “The experience of the 1960’s has shown that for military aircraft the cost of the final increment of performance usually is excessive in terms of other characteristics and that the overall system must be optimized, not just performance” Ref: Current State of the Art of Multidisciplinary Design Optimization (MDO TC) - AIAA White Paper, Jan 15, 1991 TRW Experience Industry designs not for optimal performance, but according to targets specified by a requirements document or contract - thus, optimize design for a set of GOALS. © Massachusetts Institute of Technology - Prof. de Weck and Prof. Willcox Engineering Systems Division and Dept. of Aeronautics and Astronautics
16888 esd Lecture Outline ESD.J7 Motivation -why goal programming? EXample: Goal Seeking in EXcel Case 1: Target vector T in Range Isoperformance Case 2: Target vector T out of Range Goal Programming Application to Spacecraft Design Stochastic Example: baseball Many-To-One Forward Perspective Choose x What isJ? Reverse Perspective Choose J What x satisfy this? o Massachusetts Institute of Technology-Prof de Weck and Prof Willcox Engineering Systems Division and Dept of Aeronautics and Astronautics
3 Lecture Outline Lecture Outline • Motivation - why goal programming ? • Example: Goal Seeking in Excel • Case 1: Target vector T in Range = Isoperformance • Case 2: Target vector T out of Range = Goal Programming • Application to Spacecraft Design • Stochastic Example: Baseball Forward Perspective Choose x What is J ? Reverse Perspective Choose J What x satisfy this? © Massachusetts Institute of Technology - Prof. de Weck and Prof. Willcox Engineering Systems Division and Dept. of Aeronautics and Astronautics A Domain Range B T f a x J Target Vector Many-To-One
M 16888 esd Goal Seeking ESD.J7 max(s) L.ISO mIne B X max min UB o Massachusetts Institute of Technology -Prof de Weck and Prof Willcox Engineering Systems Division and Dept of Aeronautics and Astronautics
Goal Seeking Goal Seeking max(J) T=Jreq J x * min(J) * i iso , x x i LB x , , xmin xi UB i max 4 © Massachusetts Institute of Technology - Prof. de Weck and Prof. Willcox Engineering Systems Division and Dept. of Aeronautics and Astronautics
Mles Excel: Tools-Goal Seek 16888 ESD.J7 Excel-example sin(x)/x-example single variable x no solution if T is out of range For information about ' Goal seek consult Microsoft Excel help files o Massachusetts Institute of Technology -Prof de Weck and Prof Willcox Engineering Systems Division and Dept of Aeronautics and Astronautics
5 Excel: Tools Excel: Tools – Goal Seek Goal Seek Excel - example J=sin(x)/x -0.4 -0.2 0 0.2 0.4 0.6 0.8 1 1.2 -6 -5.2 -4.4 -3.6 -2.8 -2 -1.2 -0.4 0.4 1.2 2 2.8 3.6 4.4 5.2 6 x J sin(x)/x - example • single variable x • no solution if T is out of range For information about 'Goal Seek', consult Microsoft Excel help files. © Massachusetts Institute of Technology - Prof. de Weck and Prof. Willcox Engineering Systems Division and Dept. of Aeronautics and Astronautics