Sensors presentation-06a

Editor's Notes

• #2: There has been this surge in Wireless Sensors – it is a reasonable mature market – it is not anymore confined to the walls of an R& D Lab. We will look at some of the detail including the internals of a sensor, the structure etc,. the emerging uses, what has propelled their growth and how to use them. We take a look couple of potential applications and the framework. Other than sensors- affordable computing systems, mobile devices and wireless technologies are fueling the growth – new possibilities in exploring and learning. Sensors will drive the next surge of innovation in Museums. With the advances in semiconductor technology, various sensors such as temperature, motion sensing, pressure, humidity, compass, touch and proximity are being made affordable and easy to use. Sensors will allow the museum to present the visitor with a whole new world of interactivity / engagement. Various forms of Wireless connectivity available today only make it more convenient to design and manage. This lecture will provide an introduction to the digital sensors- their characteristics and then the selection process. Also covered will be the common requirements to be considered in selecting wireless connectivity techniques, followed by a discussion of the approaches and likely challenges to integrating sensors into a comprehensive and useful system.
• #3: So are we looking at Sensors just because those are cool things? No I do not think so – Sensors do have wide applicability and it is more than the “cool factor” - sensors are likely to cause paradigm shift. There is small use of Sensors – but what I think will happened is much bigger acceptance in the usage sensors. Traditionally sensors have been used in museums to measure the ambient conditions such as light and humidity for preservation purposes. The digital IC based sensors of today provide data that can be monitored remotely with an automated system configured to respond appropriately. The automated system can also log data to help in planning and maintenance.
• #4: Sensors are much more accurate beyond; often beyond human levels of cognition – huge mtbf unlike human...
• #5: Sensory data comes from multiple sensors of different modalities/requirements often in distributed locations It is a pipeline – one stage after the other
• #6: Combining Sensors with traditional computing systems – hand held, PDA, Computer systems can enhance and extend the fun in learning. Smart environments instrumented with sensor-and-wireless-enhanced objects would be able to sense events and conditions about people/objects (basically the participants) and act upon the sensed information or use it as context when responding to queries and commands. What you see here is “sensing + wireless communication + embedded processing” Ubiquitous Computing term coined by mark Weiser – he identified it as the thirdwave in Computing
• #7: In here the sensor talks to a Link / Agent – it is also conceivable that Sensor Net elements can be designed/implemented in such a way that the data from one sensor will hop to the adjacent sensor until the data reaches the main LAN.
• #9: Measurand- A physical quantity, property, or condition which is measured. A transducer is a device that converts one type of energy to another. Can either be a Sensor or Actuator. Sensor detect energy in one form and report in another form. Such as Pressure, Temperature, Airbag,... Actuator receives energy and generates action such as loudspeaker, electric motor, .. (electromechanical output devices are generically called actuators)‏ For high precision Capacitive sensors – and longer range laser or optical based sensors Eddy-Current sensor tolerance of dirty environment also used for position measurement/sensing as in the disk drives
• #10: Electric current depending on the context, a flow of electric charge (a phenomenon) or the rate of flow of electric charge (a quantity). Pressure Sensor
• #12: SMART
• #13: Virtual sensor estimates the properties in conjunction with physical sensors. Virtual sensors manage drifts, calibration
• #14: Most wireless sensors, particularly those based on IEEE 802.15.4 or 900 MHz radios, are designed to use power very conservatively. 900MHz can propagate further (less attenuation), whereas 2.4GHz based protocols handle obstruction better (900MHz ISM in NA, Aus. & Israel)‏ 802.15.4 standardizes the MAC and PHY – the upper stacks (as in WirelessHART and ZigBee) are not compatible. (PHY 868MHz in Europe + 900Mhz elsewhere + 2.4GHz)‏ Wireless Sensors – the required data rate, low energy consumption and low cost are paramount Wi-Fi/802.11 – Security, QoS and Bandwidth are important
• #15: In a cluster tree network, each node connects to a node higher in the tree until the data reaches the gateway. This simple algorithm may be used with any wireless radio technology. Finally, in a mesh network, nodes can connect to multiple other nodes in the system and pass data through the most reliable path available. If one link goes down, affected nodes can pass data through another path to reach the gateway. Most IEEE 802.15.4-based devices employ some type of mesh network topology, because of this self-healing effect. In Star all sensors transmit directly to the central data collection point. Mesh network best over large distances, harsh RF environments, to avoid 1 single point of failure
• #16: Advances in the computing technology promotes the “sensing and act” on the physical environment suggesting the “person to physical world” connection is closer and achievable than ever.
• #17: Having sensors and wireless connectivity is only the first part of the puzzle – the widdleware services is essential for a successful SUI
• #19: QoS - it maybe OK to miss temperature samples but not necessarily that of the orientation sensor
• #20: Generate information such a Kid A is in the corner near Pyramid A
• #21: ELP – manages the purpose of the tool or the exhibit ... such as (i) Weather Station – it will be weather science study that is adjusted to the age group (ii) Earth navigator – it will be region & climate study l CM – Manage local data, share if necessary data with similar systems (Database Mgmt)‏ ELI – It handles the UI and rules management To summarize the three key challenges are to be handled are - creating networked sensing approaches - networking protocols optimized for large scale and high density sensor presence - processing and analysis of data generated by all these sensors
• #26: Ubiquitous Computing "that which informs but doesn't demand our focus or attention." Problem solving in nature – unstructured because of the kind of data that is collected to make sense out of it. And then react to it in realtime in a context sensitive fashion Toys of Tomorrow and Music Toys programs at MIT's Media Lab
• #29: For high precision Capacitive sensors – and longer range laser or optical based sensors Eddy-Current sensor tolerance of dirty environment also used for position measurement/sensing as in the disk drives Security aspects are key to while designing proximity sensors. Hall effect is another type of electromagnetic sensor - production of a voltage in a current-carrying semiconductor in the presence of a magnetic field. Thermocouples based on Seebeck effect. Resonant-Temperature sensor based on the property of SiO2 to exhibit a change in resonant frequency depending on temperature change. Optical transducers can be optimized for different frequencies of light – visible and non-visible so that you can have infrared detectors, ultraviolet detectors and so on.
• #30: Chemical Transducers used in environmental monitoring Chemiresistors are expensive because of the specialized nature – nevertheless it is very accurate. It uses electrodes that are coated with specialized chemical agents that change their resistance when exposed to certain challenge agents. Array of biosensors are put together for an Electronic nose. Em Spectrum sensors used in autonomous vehicle navigation. It requires expensive DSP techniques including edge detection, segmentation, motion analysis etc., Acoustic sensors also uses Doppler techniques for the measurement of velocities Acoustic Wave Sensors uses the changes to the characteristic of the propagation path effect the velocity and/or amplitude of of the acoustic wave – these sensors are often used in conjunction with materials that demonstrate Piezoelectric effect. It I perhaps the most versatile of sensors – because it has been used to sense many physical properties
• #34: Predominantly used as spatially distributed autonomous sensors to monitor physical environment conditions.
• #37: Sensors when coupled with the growth in display technologies and tactile feedback technologies will open a wavefront of innovation in user interaction and exhibit design.
• #38: When the user touches the screen, a position signal is sent to the microprocessor. The host application interprets this position and commands the lightweight TouchSense player, embedded on the processor, to play a specified tactile effect, such as the perception of a button press. Haptics is a catchall term for sub-types including Tactile (the sense of pressure applied through skin), kinaestehtic (motion of the body),