Smart sensors are an extension of traditional sensors to those with advanced learning and adaptation capabilities. The system must also be re-configurable and perform the necessary data interpretation, fusion of data from multiple sensors and the validation of local and remotely collected data.These sensors therefore contain embedded processing functionality that provides the computational resources to perform complex sensing and actuating tasks along with high level applications. The functions of an smart sensor system can be described in terms of compensation, information processing, communications and integration. The combination of these respective elements allow for the development of these sensors that can operate in a multi-modal fashion as well conducting active autonomous sensing. Compensation is the ability of the system to detect and respond to changes in the network environment through self-diagnostic routines, self-calibration and adaptation.
A smart sensor must be able to evaluate the validity of collected data, compare it with that obtained by other sensors and confirm the accuracy Information processing encompasses the data related processing that aims to enhance and interpret the collected data and maximize the efficiency of the system, through signal conditioning, data reduction, event detection and decision making.
Communications component of sensor systems incorporates the standardized network protocol which serves to links the distributed sensors in a coherent manner, enabling efficient communications and fault tolerance. Integration in smart sensors involves the coupling of sensing and computation at the chip level. This can be implemented using micro electro-mechanical systems (MEMS), nano-technology and bio-technology. Validation of sensors is required to avoid the potential disastrous effects of the propagation of erroneous data. The incorporation of data validation into smart sensors increases the overall reliability of the system .Data fusion techniques are required in order combine information from multiple sensors and sensor types and to ensure that only the most relevant information is transmitted between sensors.
What is a Smart Sensor System?
1. Network Capable Application Processor (NCAP) where control and data correction takes place
2. Transducer Interface Module (TIM) (one or more) containing the transducer and data
NCAP (Network Capable Application Processor)
TIM Discovery and Control
Data Correction Interpretation of TEDS Data
Message Encoding and Decoding
TIM (Transducer Interface Module)
Analog Signal Conditioning
Analog to Digital Conversion
Minimum Interconnecting Cables
The number of cables and cable lengths dictated by traditional star topologies of interconnecting analog transducers to a central signal processing equipment has a detrimental impact on all aspects of a measurement system. These factors decrease the accuracy and reliability of measurements, decrease system performance, and increase system operating costs.
The multi-drop sensor network architecture of the proposed system allows drastic reduction of interconnecting cables. The Smart Sensor System interconnects all of the transducers through a common digital bus cable. The centralized, bulky electronic boxes typical of traditional measurement systems are replaced with miniature modules strategically distributed throughout the setup.
Reliability is improved by reducing the total number of interconnecting cables and including Build-in-Test (BIT) features. Self test adds a higher level of confidence that a given measurement channel is alive and working properly.
Large numbers of analog transducers result in difficult-to-manage, large and long bundles of cables carrying analog signals which are susceptible to being corrupted by EMI/RFI noise. Cables carrying digital signals are more immune to these problems and are easier to interface than cables carrying analog signals. Higher measurement accuracy is obtained by digital correction over the operating temperature range of both the transducers’ sensitivity and the analog signal conditioning instrumentation.
Easy to Design, Use and Maintain
The primary concern of users of sensor information is to accurately measure physical phenomenon in engineering units such as Pascal, meters, m/sec2, g’s, PSI, etc. To achieve this goal, the user needs to take into account installation issues such as types of transducers to their measurement system; and selecting the proper analog amplifier settings (sensitivity-gain normalization, type of filter, excitation voltage-current, etc.) for each analog transducer. Transducer Electronic Data Sheet 1 (TEDS) stored in each smart sensor and interface module helps to reduce the complexity of the system design, integration, maintenance and operation. Features such as transducer identification, self-test, test setup configuration, configuration status, etc. can be performed under computer control with minimal need for any manual trimming or adjustments. The smart sensors and interface modules exhibit plug-and-play features to ease the measurement system usage.
Scalable -Flexible System
The new network measurement system accepts different types of transducers, including traditional analog types as well as new smart network sensors. It allows for easy expansion or reduction in the number of measurement channels. This is possible with the use of Intellibus Interface Modules (IBIM).
Small Rugged Packaging
The proposed measurement system components are small, lightweight and packaged to operate under demanding environmental conditions typical of aerospace applications such as high vibration, high temperature, high pressure, humidity, EMI/RFI, etc.
Design, operating and maintenance costs are drastically reduced by implementing a system with all of the above listed attributes. The initial capital investment may be similar or slightly higher than traditional systems; however, this marginal additional expense is far outweighed by savings in other areas. A standard hardware interface for all transducer types will eventually reduce the capital equipment costs. A standard software interface (standard data interchange) would greatly reduce ongoing operating and maintenance costs.
A single smart sensor can measure pressure, temperature, humidity, gas flow and infrared, chemical reaction surface acoustic vapour etc.
• Required use of predefined embedded function during the design of the smart sensor
• The smart sensor consist of both actuators and sensors
• Sensor calibration has to be managed by an external processor
• In wired smart sensor, complexity is much higher as a consequence has to be managed by an external processor.
• The cost is high
APPLICATIONS OF SMART SENSOR
Monitoring of Temperature Using Smart Sensors Based on CAN Architecture
The implementation of smart sensor for monitoring temperature and for communicating among them self using the protocol CAN(controller area network).A smart sensor has the capacity to make decisions based on data and command received.
Bluetooth Smart Sensor Module Rear Panel
Bluetooth sensor is increasingly being used for applications such as portable heart rate or blood pressure monitors that are controlled via a smartphone and collect data over a period of time. It can be used in remote control
A Smart Sensor Architecture for Marine Sensor Networks
An MSN is the name given to collection of instruments and data acquisition systems which work together to derive data from the marine environment, through communication link. cabled MSNs, are optimally suited to a continuous observation of the ocean; offering high band width telemetry