smart sensors seminar

14
SMART SENSORS (INTELLIGENT SENSORS) Sensors Analog Signal Processing Unit Converter Unit Micro controllers

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Page 1: Smart sensors seminar

SMART SENSORS(INTELLIGENT SENSORS) Sensors Analog Signal Processing Unit Converter Unit Micro controllers

Page 2: Smart sensors seminar

A sensor with interfacing circuits capable of performing the following functions is said to be a smart sensors

Automatic rangingAutomatic calibrationAutomatic decision making

Page 3: Smart sensors seminar

Typical Intelligent sensor and actuator

Page 4: Smart sensors seminar

• The properties of an intelligent field devices are:Automatic ranging and calibration through a built in difital system

Auto acquisition and storage of calibration constants in the local memory of filed devices

Auto configuration and verification of hardware Auto correction of offsets, time and temperature driftsAuto linearization of non linear characteristicsCommunication through a serial bus

Page 5: Smart sensors seminar

• The motive behind development of smart sensors is:Compensation for the non ideal behavior of sensorsProvision of communication of process data with the host system.

Signal conditioning based on the output of the sensor• Smart sensors provide new sensing methods improved

computing capability and digital communications.

Page 6: Smart sensors seminar

A sensor interfaced with a host system

Page 7: Smart sensors seminar

SENSOR:

• The sensor provides an electric output in response to the physical quantity it receives as input .

• The advanced sensor technology are Semiconductor sensors, micro machined semiconductors and IC sensors.

Page 8: Smart sensors seminar

Analog Signal Processing Unit• The ASPU is the analog signal processing unit that

consist of the power supply, amplifiers and filters.• The power supply generally refers to the power supply to

the sensor• The power source can either be a D.C. source or a A.C.

source as per the application demands.

Page 9: Smart sensors seminar

• Amplifier is another component found in almost all sensor system.

• Filters are used to remove unwanted noise signals caused when gain requirement is high.

• Analog filters are commonly used because digital filters consumes more power.

Page 10: Smart sensors seminar

Convertor Unit• The convertor unit can either be a D.C. source or A.C.

source as the application demands.• Data conversion from analog amplitude to frequency is

often done for convenient signal transmission internally or externally and for subsequent digital conversion.

• Voltage-frequency conversion is carried out using multivibrators.

Page 11: Smart sensors seminar

Microprocessor• The micro controller is used to overcome the following

defects in a sensor:• Non linearity• Noise• Response time• Drift• Cross sensitivity• Interference

• Sometimes the sensor responds to additional variables apart from the measured variables.

Page 12: Smart sensors seminar

• Some compensation techniques are followed to maintain the sensitivity:

• Monitored compensation• Structural compensation• Tailored compensation• Deductive compensation

Page 13: Smart sensors seminar

• MONITORED COMPENSATION: The compensation is done by devising an algorithm that monitors the change in response characteristics because of the interfering quantity.• STRUCTURAL COMPENSATION: Care is taken while designing the sensor such that desired o/p is derived through differential mode and interfering signals are derived through common mode are rejected.

Page 14: Smart sensors seminar

• TAILORED COMPENSATION: Compensation is done individually on each sensor depending on its performance and response to inputs. Here a dedicated algorithm has to be developed or specialized analog module has to be incorporated.• DEDUCTIVE COMPENSATION: When the variables are not physically accessible, model reference data sets are considered and compensation technique is called deductive compensation.