SENSORS

POSITION / SPEEDWhat is a position/speed sensor?Position/speed sensors are a collection of various sensorstypes using various technologies to achieve linear orrotational position detection, or speed measurement. Themost common technologies used are magnetic (i.e. Halleffect or magnetoresistive), optical sensor and resistivecontact sensing.ApplicationCasesPositionSpeedReal Life ExamplesNeedle position in industrialknitting machinesRotary switches (human machineinterface)AC/DC motor position controlRoboticsControllers for injection speed ofmolding machineGear rotation speed and direction inFactory Automation equipmentMotor controllers for vehiclesImportant selection parametersLinear vs. RotaryDifferent technologies are used in linear or rotary position/speed measurement. For linear measurement, Halleffect, optical switches and passive devices such aslinear potentiometers are commonly used. For rotarymeasurement, magnetic or optical rotary encoders are moreoften encountered.Magnetic vs. OpticalBoth magnetic and optical sensors are useful for noncontactposition & speed measurement. Magnetic sensorsare immune to contamination and are ideal in harsh ordirty environments or submerged in fluids like motor oil.Optical sensors, generally transmissive or reflective types,are more suitable for clean environments free of dust andcontamination. For contact-type position/speed sensing,passive devices such as potentiometers are often used, asare rotary or linear encoders of this type.Typical applicationsPosition, and indirectly, speed sensors, have a wide rangeof industrial uses such as manufacturing processes, valveand flow controls, and robotics and CNC machines;automotive uses include engine monitoring & control, brakingand enhanced stability systems; commercial ones includecopiers, printers and scanners, elevators, and many kinds ofuser input devices or man-machine interface; aerospace andother applications abound.POSITION / SPEED61www.FutureElectronics.com/Sensors