Study of noise readings in infrared sensors and their effect

in the Khepera Miniature Robot’s performance

Saúl J. Vega Daisy A. Ortiz

Advisor: Raúl E. Torres, Ph.D., P.E.

Background

• Robots– Management of hazardous waste– Moving of heavy equipment– Ocean and space exploration– Fire extinguishing

• Artificial Intelligence– Knowledge-based– Behavior-based

Background (cont.)

• Behavior-based Artificial Intelligence– Subsumption Architecture (SA)

• Build behaviors from smaller sub-behaviors

• SA rely heavily on sensory input– Noise cause disturbance in robot

operation

Problem Statement

• Avoid negative effect of fluorescent lamps on infrared sensory readings

Oh! No!

Objectives

• Determine the effect of noisy readings on robot performance

• Determine the effect of filtered sensory on robot performance

Methodology

• Review of literature

• Simulation study

• Hardware implementation– Real Khepera used in testing

• Filters design

• Testing-platform development– Braitenberg vehicle algorithm

• Comparison of results

Our Star:Mr. Khepera

Anatomy of the Khepera

Microprocessor

IR-Sensors

Wheels & DC-Motors

Insights of Our Hero

Microprocessor IR-Sensors Wheels & DC-Motors

Simplified Braitenberg Algorithm

Turn Right

Obstacle onLeft side?

No

Yes

Obstacle onRight side?

Turn Left

Yes

NoMove Forward

No Obstacle onBack?

EndYes

No filter in Darkness

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Averaging in Light

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Results

• On darkness– Slow filter response when approaching obstacle– Even slower when moving away from obstacle

• On light– Acceptable filter response time when approaching

obstacle– Acceptable filter response time when moving away

from obstacle– Noisy readings greatly reduced

Results (cont.)

• Satisfactory performance of Braitenberg algorithm without filtered readings on darkness

• Problems using filters with Braitenberg algorithm– Robot slow to react to filtered sensory readings

Conclusions

• Fluorescent light noise cause serious effects on Khepera’s performance

• Digital filters proved to be useful in reducing noise in sensory readings

• Filters performance are greatly affected by levels of ambient light

Future Works

• Braitenberg algorithm modified to allows detection of ambient light– Activate filters on high levels of ambient light– Disable filters on low-light conditions

• Develop user-friendly program for testing algorithms and filters

Questions?