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Active Vision Sensor Planning of Active Vision Sensor Planning of CardEye PlatformCardEye Platform

Sherif Rashad, Emir Dizdarevic, Sherif Rashad, Emir Dizdarevic,

Ahmed Eid, Chuck Sites and Aly FaragAhmed Eid, Chuck Sites and Aly Farag

ResearchersResearchers SponsorSponsor

US ArmyUS Army

Mounted Maneuver BattleSpace LabMounted Maneuver BattleSpace Lab

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Objective

The main objective of this project is to design and implement an active sensor planning algorithm for the CardEye platform. For this system, generalized camera parameters such as position, orientation, and optical settings have to be determined according to the new position of the robot arm so that its features are within the field of view of the CardEye cameras and are in focus.

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System Overview Robot Arm

Super Computer

Transmit current coordinates to super computer using the

serial port

Reading robot coordinates from super computer

Sensor Planning

Sensor Planning

Sending planned parameters to CardEye to adjust the cameras’ settings according to the new

settings

CardEye active vision system

Sending the captured images of robot arm to

be displayed

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CardEye Platform•This platform uses an agile trinocular vision head contains three CCD cameras (c’, c”, c’’’) with their lenses for the automated zoom and focus.

•The cameras are placed at equal distances from each other. The cameras can translate (t) along their mounts to change the baseline distance.

•At the same time, the cameras can rotate towards each other to fixate to a point in space by changing the vergence angle ().

•The target is assumed to be inside a sphere that has a radius (R).

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Geometry for Sensor Planning

X

Y

Z

O

C’

C’’’C’’

t

tt

d

GR l

l

l

d

ttan 1

Object contained in a sphere

Optical axisFixation point

Optical Center

Camera Parameters:• translation (t)• vergence angle ()• filed of view angle()(for zoom setting)

R

l GC’

22 dtl

22

1

dt

Rsin

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• The system's fixation point is the center C of the sphere. The center of the sphere is at distance d from the origin along the z axis.

• Every time, the sensor planning module will have the radius R and the distance d only (to be calculated from the initial position and the current coordinates of the robot).

• For suitable planning, we should calculate t for translation, for adjusting the vergence angle so all cameras can fixate on the same point in 3D space, and to set the zoom of the cameras.

Sensor Planning

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System Constraints(a) Overlap Constraint

'd2

t3tan2 1

2

td'd

22

3t2

C’

C’’’

G

R

3t2

d’O’

where

• By maximizing , overlap area is also maximized.• By decreasing t, we increase the overlap.

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System Constraints(b) Disparity Constraint

2'd

Rt32

3t2

C’

C’’’

R

3t2

PGd’

O’

By increasing t, more adequate depth information can be recovered from the imaged object.

Total Angular Disparity

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• For effective reconstruction, the images must display adequate depth information (increase t) and have a fairly large overlap area (decrease t).

SolutionSolution:

1. Analyze the effect of object distance on overlap and disparity angles and compute translation t.

2. Normalize the translation values based on the physical range of the system translation.

3. Estimate the system workspace

4. Repeat step 1 and compute t as function of object distance d.

Analysis of System Constraints

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Five cases of object size are analyzed and their solution for t is estimated for each case:

Case 1:Case 1: 0.2m <R < 0.3m, 1.200m < d < 7m

t = 0.005622 d2 + 0.04068 d+ 0.04125 [m]

Case 2:Case 2: 0.3m < R < 0.5m, 1.925m < d < 7m

t = 0:005812 d2 + 0:04702 d+ 0.01307 [m]

Case 3:Case 3: 0:5m < R < 0.7m, 2.650m < d < 7m

t = 0:006205 d2 + 0:05530 d+ 0.09068 [m]

Case 4:Case 4: 0.7m < R <0.9 m, 3.375m < d< 7m

t = 0:006882 d2 + 0:06668 d+ 0.20372 [m]

Case 5:Case 5: 0:9m < R <1.0m, 4.100m < d < 7m

t = 0:007990 d2 + 0:08380 d+ 0.37802 [m]

2nd-order polynomial equation for sensor placement t

3rd-order polynomial equation was for the voltage used to control the zoom in lenses

112233out,z 10x1.4273810x1.8004α10x1.5915α10x6.1900V

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After Sensor Planning

Sample of Results (1)

Before Sensor Planning

At d=2.091m and R=0.399m

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At d=1.525m and R=0.200m

After Sensor PlanningBefore Sensor Planning

Sample of Results (2)