Motor Control Engineering View

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Motor Control Engineering View
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Topics

• 1- Muscle and Spinal Cord Models
• 2- Classic Control/Control Variables
• 3- Model Based Strategies

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Stark, Lawrence W. 1968. Neurological Control
Systems Studies in Bioengineering. New York
Plenum Press.
Classic Control (Modeling Eye Movement)
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Control Variables

• 1- Force !?
• 2- Position !?
• 3- Velocity !?
• 4- Stiffness !?
• 5- Viscosity !?
• 6- Impedance !?

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Stein, R.C. (1982) Behavioral and Brain Sciences

• What Muscle Variable(s) Does the Nervous System
  Control in Limb Movements?

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Stiffness Control
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Muscle Stiffness
F k ( X X0) ????? ?? ??? (????)
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Stiffness Control (cont.)

• K F/X
• K gtgt 1 gt Force Control
• K ltlt 1 gt Position Control

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Stiffness Control (cont.)

• 1- Feldman Bizzi (EPH), 1966,1979,1986
• 2- Houk (Stiffness and Reflex), 1979
• 3- Hasan, 1986

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How CNS May Changes Joint Stiffness?

• 1- Muscle active characteristic
• 2- Muscle passive characteristic
• 3- a-? co-activation spinal reflex loop (muscle
  spindle)
• 4- Co-contraction

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Stiffness Control Diagram
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Load Effect
ßv Tf - Td/s
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Stiffness Control Diagram (cont.)
CNS
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Impedance Definition

• Winters et al. (1988)
• the automatic capability of the system to
  resist an applied load before voluntary
  intervention takes place

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Impedance Control

• 1- Hoffer (1982). Central Control and Reflex
  Regulation of Mechanical Impedance The Basis for
  a Unified Motor-Control Scheme. Behavioral and
  Brain Sciences

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Impedance Control (cont.)

• 2- Stein, R. C., (1982). What Muscle Variable(s)
  Does the Nervous System Control in Limb
  Movements? Behavioral and Brain Sciences

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Impedance Control (cont.)

• 3-Hogan, N., (1984a). Adaptive Control of
  Mechanical Impedance by Coactivation of
  Antagonist Muscles. IEEE Trans. on Automatic
  Control,
• Hogan, N., (1985a). Impedance Control An
  Approach to Manipulation Part I-Theory. Journal
  of Dynamic Systems, Measurement, and Control,
• Hogan, N., (1985c). The Mechanics of Multi-Joint
  Posture and Movement Control. Biological
  Cybernetic, 52, 315-331.

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Muscle 2-D Characteristic
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Joint Impedance
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Is Joint Impedance Short-Term Predictor?
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Joint Impedance (cont.)
Output
Reference
PD
Plant
Control Signal
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• Smith, A. M. (1996) ,
• Does the Cerebellum Learn Strategies for the
  Optimal Time-Varing Control of Joint Stiffness?
  Behavioral and Brain Sciences