Tuesday, September 30, 2014

IAC 2014 - Day 2: An Ode to my Yoda

Today, I will abandon the approach of summarizing my experience at the IAC, and focus solely on the morning session on space structures.  In particular, I want to highlight the talk that was given by Professor Arun K. Misra, my mentor.

He is the Yoda to my Skywalker, the Dumbledore to my Potter.  Much of my knowledge of space research and the reason for my initial interest in space elevators came from Misra.  He supervised my Masters project from 2004 to 2006, and we have published several papers together since then.  He is kind and acts with integrity, and has served as a model for professionalism in my eyes.

I will never forget my initial meetings with Professor Misra in 2004, when I expressed my concern that the project will be difficult for me to carry out.  He quietly laughed, and said "You know, building the first space elevator will be hard... Your project, studying its dynamics, will be easy."  He curbed my definition of hard work, and in so doing, helped me mitigate a common fear that young professionals commonly face - that of daunting tasks.

This morning, Misra is giving a special talk: the Paolo Santini Memorial Lecture.  It is an annual honor bestowed upon significant figures in the space world, particularly in the materials and structures area.  He is introduced as the father of space robotics in Canada.  When he arrives on the stage, he humbly corrects the session chair that in fact Peter Hughes is the father of space robotics in Canada.

Today, Misra's presentation is entitled "Dynamics Modeling and Control of Flexible Space Manipulators".  His talk summarizes the past three decades of dynamical modelling and eventual in-orbit use of manipulators, such as the Canadarm I and II, and more recently, Dextre.  The Canadarms can manipulate structures that are nearly one hundred times their mass.  While unthinkable on Earth, space manipulators do not contend with the weight loads of the bodies they grapple with, only their inertia.

Early manipulators moved extremely slowly due to the primitive control systems on-board.  Advanced numerical techniques and higher computational capability of computers in space has made space manipulation less laborious.

He ends his talk with what he says will be the next big thing in space robotics, "reactionless capture" (indeed, two subsequent talks in this session deal with this topic).  

The idea is that in the past, the mass of the base spacecraft, which the manipulator is fastened to, is far greater then the manipulator itself, as well as any payload it intends to capture.  As a result, the effect of manipulations on the mother spacecraft is usually small.  In the coming decades, smaller spacecrafts and larger docking bodies will become typical, and manipulations will have large dynamic consequences on the base.  The challenge is then to make complex manipulations, while simultaneously transferring minimal load to the base.  This is doable provided that the manipulator has built-in redundancy (more motors than it would otherwise need).  This way, the arm can accomplish what it needs to do, but do it in such a way that the ensuing loads are cancelled by the motion of the manipulator itself.

During the introduction, the session chair also mentions that Professor Misra has authored and co-authored more than 230 papers (journals and international conferences).  I conclude that I`ll never be that prolific, but then quickly look at it in another way: I consider myself fortunate to have been involved with a handful of those papers.

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