PASCAL - Pattern Analysis, Statistical Modelling and Computational Learning

Delayed Feedback Control Requires an Internal Forward Model
Dmitry Volkinshtein and Ron Meir
Systems and Control Letters Volume NA, 2009.

Abstract

Biological motor control provides highly eective solutions to dicult control problems in spite of the complexity of the plant and the signicant delays in sen- sory feedback . Such delays are expected to lead to non trivial stability issues and lack of robustness of control solutions. However, such diculties are not observed in biological systems under normal operating conditions. Based on early suggestions in the control literature, a possible solution to this conundrum has been the sugges- tion that the motor system contains within itself a forward model of the plant (e.g., the arm), which allows the system to `simulate' and predict the eect of applying a control signal. In this work we formally dene the notion of a forward model for de- terministic control problems, and provide simple conditions that imply its existence for tasks involving delayed feedback control. As opposed to previous work which dealt mostly with linear plants and quadratic cost functions, our results apply to rather generic control systems, showing that any controller (biological or otherwise) which solves a set of tasks, must contain within itself a forward plant model. We suggest that our results provide strong theoretical support for the necessity of for- ward models in many delayed control problems, implying that they are not only useful, but rather, mandatory, under general conditions.

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EPrint Type:Article
Project Keyword:Project Keyword UNSPECIFIED
Subjects:Brain Computer Interfaces
ID Code:5266
Deposited By:Ron Meir
Deposited On:24 March 2009