Controlling Physical Interaction
Neville Hogan
Sun Jae Professor of Mechanical Engineering and Brain and Cognitive Sciences
MIT
Human dexterity and agility vastly exceed contemporary robots despite noisy
sensors, slow actuators and vastly slower communication. How is that possible? I
believe insight may be gained by studying the control of physical interaction,
critical for that quintessentially human ability, the use of tools.
Controlling physical interaction presents unique challenges not encountered in
controlling movement: conventional control and information processing theory is
based on uni-lateral operations (inputs yield outputs but not vice-versa) but
physical interactions are bi-lateral. As a result, conventional theory does not work
well. Instead, concepts grounded in physical system theory have proven
effective. Computers and brains essentially process information; physical
systems process energy. The main constraints on information processing are
temporal causality and boundedness. Physical systems are additionally
constrained by mechanical physics—and that may be used to advantage.
The interface between information processing and energy processing is provided
by muscle. One of their key properties is modifiable mechanical impedance. I will
review examples showing how this can dramatically simplify the control of
physical interaction and argue that modifiable mechanical impedance is a
key dynamic primitive that may contribute to the spectacular performance of
humans (Hogan and Sternad, 2012; Hogan and Sternad, 2013).
Hogan, N. and Sternad, D. (2012). "Dynamic Primitives of Motor
Behavior." Biological Cybernetics 106: 727-739.
Hogan, N. and Sternad, D. (2013). "Dynamic Primitives in the Control of
Locomotion." Frontiers in Computational Neuroscience 7(71): 1-16.