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ECE 450 Introduction to Robotics. Section: 50883 Instructor: Linda A. Gee 10/26/99 Lecture 13. Tactile and Proximity Sensing. Tactile Sensors provide collision indication with surroundings in terms of direct physical contact; used on automated guided vehicles (AGVs) Proximity Sensors
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ECE 450 Introduction to Robotics Section: 50883 Instructor: Linda A. Gee 10/26/99 Lecture 13
Tactile and Proximity Sensing • Tactile Sensors • provide collision indication with surroundings in terms of direct physical contact; used on automated guided vehicles (AGVs) • Proximity Sensors • provide advance warning of the presence of an object and are non-contact devices
Tactile Sensors • Tactile sensor methods • Contact closure • Magnetic • Piezoelectric • Capacitive • Photoelectric • Magnetoresistive • Piezoresistive • Ultrasonic
Tactile Sensors for Mobile Robots • Tactile feelers or antennae • Tactile bumpers • Distributed surface arrays
Tactile Feelers • Active • possess mechanical components • Passive • rely on relative motion between the robot and the object
Tactile Bumpers • Simple sensor • designed to form a contact closure when pressure is applied to the bumper • other actuators can be used to trigger control or decisions concerning course of action
Distributed Surface Arrays • Skin-like sensor used with manipulators • uses an outer surface, typically rubber to determine the contact or compression of the surface • provides robotic orientation sensing for industrial applications
Proximity Sensors • Proximity sensor methods • Magnetic • Inductive • Capacitive • Ultrasonic • Microwave • Optical
Magnetic Proximity Sensors • Types of magnetic proximity sensors • Magnetic reed switches: hermitically sealed • Hall Effect sensors: voltage and magnetic field • Magnetoresistive sensors: change in resistivity with motion • Giant Magnetoresistance devices (GMR): linear operation
Inductive Proximity Sensors • Commonly used in industrial sensors • capable of sensing through non-metallic materials • operating characterisitics are versatile • insensitive to cosmetic alterations • can be submerged in fluids and maintain operation • size variation determines sensing range capability
Capacitive Proximity Sensors • Detects a change in capacitance or electric field due to object presence • Capable of sensing • dielectric materials • metals
Ultrasonic Proximity Sensors • Reflective sensor • Responds to the change in the energy emitted and returned to a detector: acoustics • Distance characteristics • Detects • liquids • objects • solids
Microwave Proximity Sensors • Reflective sensor • Emits electromagnetic energy in the microwave region of the RF spectrum • Doppler shift indicates the presence of an object • Transmitter - Receiver pair required
Optical Proximity Sensors • Photoelectric sensors • Three groups • opposed: electric eye; emitter/detector beam interrruption • retroreflective: uses an object to reflect from emitter to the detector • diffuse: uses the target object to return the energy from the emitter to the detector