CS545_Lecture_5

CS545_Lecture_5 - Eye motors are very strong (inertial...

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CS545—Contents V Case Study: An Artificial Eye System Introduction to Oculomotor Control The model of the dynamics Gaze stabilization The vestibulo-ocular reflex (VOR) The optokinetic reflex (OKR) Delays Controlling the VOR and OKR Reading Assignment for Next Class See http://www-clmc.usc.edu/~cs545
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Introduction to Oculomotor Control Goals Get visual input from the entire world with high resolution foveal vision and low resolution peripheral vision Behaviors Move the fovea to interesting targets (saccades) Stabilize target on retina (VOR,OKR) Adjust focal length (accommodation) Enable stereo vision (vergence) Avoid workspace boundaries (nystagmus) Problems Delays from visual processing are about 100ms in humans, about 30-100ms in artificial systems
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Example Oculomotor Systems The human eye Vision Heads
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Example Oculomotor Systems Vision Heads
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Case Study: The VOR and OKR
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A model of the eye system Assumptions: System is a linear second order system
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Unformatted text preview: Eye motors are very strong (inertial loads are small) Independent control of pan and tilt degree-of-freedom, thus: Tilt-Axis Pan-Axis I = b k + Gaze Stabilization Gaze = e + h Head Eye h e t Target Goal: keep the eye on the target in case of visual and head perturbations! Simulink Model of Oculomotor System 3 th 2 rd 1 r du/dt retinal slip velocity u(4)-(u(3)+u(1)) retinal slip Mux Mux Delayed Retinal Slip culomotorAnimationSimple Animation function u_left u_right th_left th_right 2-eye dynamics 1 focal length 3 th-Target 2 th- Head 1 u 1 th_left 1/m s +b/m.s+k/m 2 Left Eye 1 u_left PD Control for the VOR &OKR retinal slip motor command eye pos pos vel u_PD PD u th- Head th-Target r rd th Oculomotor Animation Head Position pi/6 Target Performance of PD Control Step Input: Sinusoidal Input time retinal slip How to Improve Performance? Integrator Feedforward Control Delay Compensation...
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This note was uploaded on 02/24/2011 for the course CSCI 545 taught by Professor Schaal during the Spring '08 term at USC.

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CS545_Lecture_5 - Eye motors are very strong (inertial...

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