Electronic Instrumentation Lecturer Touseef Yaqoob1 Sensors and Instrumentation Sensors and Instrumentation

Electronic Instrumentation Lecturer Touseef Yaqoob2 What is a sensor? Formal definition: “A device that receives and responds to a signal or stimulus” (American Heritage Dictionary of the English Language)Formal definition: “A device that receives and responds to a signal or stimulus” (American Heritage Dictionary of the English Language) Informally, a sensor is a device that takes in information from the outside world. Based on the information, the sensor creates a signal on which a system can base a decisionInformally, a sensor is a device that takes in information from the outside world. Based on the information, the sensor creates a signal on which a system can base a decision –A sensor, thus, has an input and an output

Electronic Instrumentation Lecturer Touseef Yaqoob3 What is a sensor? (cont.) In our case, a sensor will measure some physical quantity and convert it into some electrical signal (e.g., a voltage)In our case, a sensor will measure some physical quantity and convert it into some electrical signal (e.g., a voltage) It is our job to quantify the properties of the sensorIt is our job to quantify the properties of the sensor In theory, you would also want to do something intelligent based on the signal (turn on a heater, sound an alarm, pass/fail an industrial part, etc)In theory, you would also want to do something intelligent based on the signal (turn on a heater, sound an alarm, pass/fail an industrial part, etc)

Electronic Instrumentation Lecturer Touseef Yaqoob4 Characterizing Sensors What are some important quantities to know about a sensor?What are some important quantities to know about a sensor? –Sensitivity –Resolution –Accuracy –Repeatability –Reliability –Response function –Dynamic range –Noise characteristics

Electronic Instrumentation Lecturer Touseef Yaqoob5 Sensing Systems What advantages do sensors have over using a human?What advantages do sensors have over using a human? –Repeatability - a sensor’s output is very stable over time whereas a human may suffer from fatigue –Reliability - a sensor usually won’t need breaks, vacations, etc… –Harsh environments - a sensor can operate in many environments that humans would complain about –Sensitivity - sensors can be significantly more sensitive than the corresponding human sense (although not always!)

Electronic Instrumentation Lecturer Touseef Yaqoob6 Traffic Control System A coil of wire sits underneath the pavement creating a magnetic field A control system monitors the current When a large conducting mass sits on top of the coil, it will change the current measured through mutual induction Turn light to green when the current changes Current System to monitor current System to monitor current