The study of various aspects of manipulator design and control is summarized, focusing on the interaction of the structure's flexible dynamics and the dynamics of the joint control system, including specific information on modeling and design, modal analysis and control, and the flexible manipulator analysis computer program, FMAP

Book, W. J.

Maizza-Neto, O.

Whitney, D. E.

English

NASA Technical Reports Server

?im1 Report on NASA Contract NAs8-28055 
hadeoffr in Manipulator Structure and Control 
Part I 
Daniel E .  Whitney 
Wayne J. Book 
Octavio Maizza-Net0 
(LASA-CR-1204S3) T R A D E O F E S  IN HRNXPULATOE N74-35306 
STRUCTURE A N 3  CONTRCL. PAET 1: SUHHARY 
Tical Report (Cassachusetts Inst. of 
Tecn.) 4 F BC 84.CG C S C L  26K UIiclas 
G 3 / 3 2  51846 
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\ 
Prepared by Department of Mechanical Engineering . - 
Massachusetts Institute of Technology 
Cambridge, Massachusetts 02139 
?or George C. Marshall Space Flight Center, NASA 
Marsh.11 Space Flight Center, Alabama 35812 
August 31, 1974 
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https://ntrs.nasa.gov/search.jsp?R=19740027193 2020-03-23T02:07:34+00:00Z
Tradeoffs in Manipulator Structure and Control 
Part I: SolOuRY 
A study of various aspects of manipulator design and control has 
been conducted, focusing on the interaction of the structure's flexible 
dynamics and the dynamics of the joint control systems. 
presented in Parts 11, 111, and IV which are sumarized below. 
Part 11: Meling, Design, and Control of Flexible Manipulator Arms. 
The results are 
Distributed and lumped parameter models of the various a r m  components 
were cambined via transfer matrices and numerical techniques were used to 
derive frequency domain information on the complete arm model. This 
aodeling technique vas used in a design context for a specific an8 under 
construction. In this use it indicated the sizing required of the structural 
members and suggested that more general conclusions on structural require- 
ments for adequate rigidity could be reached. 
that for the ass& commn form of control a rule of thumb limiting the 
arm bandwidth to one-half the lclwcrt locked actuator natural frequency 
was quite accurate for the link, joint combinations explored. 
replaces more conservative estimates of rigidity requirements. 
Additional study indicated 
This rule 
The requirements for strength (stress limitations) and rigidity were 
expresse2 nondimensionally in terns of the pertinent arm performance 
apecificattons. Analysis of single link arm based on these requirements 
indicated tho relative significance of strength and stiffness constraints 
for regions of a three direnrional space of ann specifications. 
results indicate practical application for improved manipulator control 
schemes. 
The 
2 
Part 111. M a l  Analysis and Control of Flexible Manipulator Arms. 
In order to study more advanced control schemes and to include 
nonlinear effects, additional study was undertaken. A modal approach 
is used throughout this section of the work for obtaining the mathematical 
d e l  and control techniques applied. 
mathematically by a state space description defined in terms of joint 
angles and mode amplitudes obtained from truncation on the distributed 
systes and includes the nonlinear dynamic effects. 
on the planar motion of a two link two joint ann. 
The a r m  model is represented 
The work concentrated 
The problem of controlling the system was examined via the linear- 
ized model and using a regulator type of control. 
were used for this purpose: 
rigid system with interjoint feedbacks, the Simon Mitter algorithm for 
pole allocation and sensitivity analysis with respect to parameter variations. 
An improvement in arm bandwidth was obtained that could replace the 
simpler designs explored in Part 11. 
Three basic techniques 
pole location with gains obtained from the 
The ideal geometric arrn configuration was found to be a function of 
payload sizes and programed tasks. 
The controlled system was examined under constant gains and using the 
nonlinear model for simulations following a time varying state trajectory. 
The procedure presented in this work is general and can be implemented 
to be used in more specific arm designs. 
3 
Part IV: Flexible Manipulator Analysis Program. 
The computer programs (Flexible Manipulator Analysis Programs 
or FMAP) that were used in Part I1 are documented in this section. 
Complete instructions on using P W  and examples of various features 
of the packaye are included. The Rancho Anthropanorphic Arm (RAM) 
of the Marshall Spaceflight Center is modelled as an exercise demon- 
strating the modelling procedure. Suggestions for implementing FMAP 
on a new computer system ate given as well as a listing of the program. 


Tradeoffs in manipulator structure and control. Part 1: Summary

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