Force Control: A Bird's Eye View
Joris De Schutter 1, Herman Bruyninckx 1, Wen-Hong Zhu 1, and
Mark W. Spong 2
1 Department of Mechanical Engineering, Katholieke Universiteit Leuven, Belgium
2 Coordinated Science Laboratory, University of Illinois at Urbana-Champaign,
This chapter summarizes the major conclusions of twenty years of research
in robot force control, points out remaining problems, and introduces issues
that need more attention. By looking at force control from a distance, a lot of
common features among different control approaches are revealed; this allows
us to put force control into a broader (e.g. differential-geometric) context.
The chapter starts with the basics of force control at an introductory level,
by focusing at one or two degrees of freedom. Then the problems associated
with the extension to the multidimensional case are described in a differential-
geometric context. Finally, robustness and adaptive control are discussed.
The purpose of force control could be quite diverse, such as applying a con-
trolled force needed for a manufacturing process (e.g. deburring or grinding),
pushing an external object using a controlled force, or dealing with geometric
uncertainty by establishing controlled contacts (e.g. in assembly). This chap-
ter summarizes the major conclusions of twenty years of research in robot
force control, points out remaining problems, and introduces issues that, in
the authors' opinions, need more attention.
Rather than discussing details of individual force control implementa-
tions, the idea is to step back a little bit, and look at force control from a
distance. This reveals a lot of simi][arities among different control approaches,
and allows us to put force control into a broader (e.g. differential-geometric)
context. In order to achieve a hig:h information density this text works with
short, explicit statements which are briefly commented, but not proven. Some
of these statements are well known and sometimes even trivial, some others
reflect the personal opinion and experience of the authors; they may not be
generally accepted, or at least require further investigation. Nevertheless we
believe this collection of statements represents a useful background for future
research in force control.
This chapter is organized as follows: Section 2. presents the basics of
force control at an introductory level, by focusing at one or two degrees
of freedom. Section 3. describes in a general differential-geometric context
the problems associated with the, extension to the multi-dimensional case.