Robots,
discussed in Parts 84 and 85, are a subset
of 'smart structures'. Smart bridges, smart surfaces, smart wings of aircraft,
and smart cars are some other examples of smart structures.
In all
probability there is no clear distinction between life and nonlife. This will
become more and more apparent as we humans make progress in the field of smart
structures (Wadhawan (2007): Smart Structures: Blurring the Distinction Between the Living and the Nonliving).
Smart or
'adaptronic' structures are defined as structures with an ability to respond
adaptively in a pre-designed useful and efficient manner to changing
environmental conditions, including any changes in their own condition. The
response is adaptive in the sense that two or more stimuli or inputs may be
received and yet there is a single response function as per design. The
structure is designed to ensure that it gives optimal performance under a
variety of environmental conditions.
Any smart
structure, biological or artificial, typically has a host structure or ‘body’,
which has an interface with a source of energy. The body houses or supports one
or more sensors (e.g. ‘nerves’) and one or more actuators (e.g. ‘muscles’). The
sensors and the actuators interface with a control centre or ‘brain’. Since
both sensors and actuators interface with the control centre, they interface
with each other also, albeit indirectly. In a good smart structure there is
extensive and continuous feedback and communication of information among the
various subunits.
The basic
action plan of a smart structure is essentially as follows: The input of data
by the sensors is analysed by the control centre. If the course of action is
clear, the control centre signals the actuators to take the action. If the
course of action is not clear, the control centre directs the sensors to
collect additional data. This goes on cyclically, till the course of action is
clear, and then the action is taken. The action taken depends on the overall
purpose or objective.
To consider
the example of a human (obviously a smart structure), if a person puts his /
her hand on a hot surface, the tactile sensors send a signal to the brain,
which then immediately directs the muscles to take the hand away from the hot
surface. The purpose of the smart structure here is to survive and propagate.
Since the
smartest structures around us are those designed by Nature through aeons of
trial and error and evolution, it makes sense for us to emulate Nature when we
want to design artificial smart structures. In fact, an alternative definition
of a smart structure can be given as follows:
Smart
structures are those which possess characteristics close to, and, if possible,
exceeding, those found in biological structures.
Sensors
Sensing
involves measurement followed by information-processing. The sensor may be a
system by itself, or it may be a subsystem in a larger system (e.g. a complete
smart system). In artificial smart structures, optical fibres constitute the most versatile sensors. A
variety of ferroic materials also serve as sensor materials. Some notable
examples are piezoelectric materials like quartz and PZT, and relaxor
ferroelectrics like PMN-PT.
The concept of
'integrated sensors' has
been gaining ground for quite some time. Typically, there is a microsensor
integrated with signal-processing circuits on a single package. This package
not only transduces the sensor inputs into electrical signals, but may also
have other signal-processing and decision-making capabilities. There are
several advantages of integrated sensors: better signal-to-noise ratio;
improved characteristics; and signal conditioning and formatting.
Actuators
An actuator
creates controllable mechanical motion from other forms of energy. Materials
used for sensor and actuators in smart structures fall into three categories:
ferroic materials; nanostructured materials; and soft materials.
Microactuators
are the current rage. At present it is usually necessary that they be
compatible with the materials and processing technologies used in silicon
microelectronics. The two main types of microactuators are ‘mechanisms’
and ‘deformable microstructures’. The former provide displacement
through rigid-body motion. The latter do this by mechanical deformation or
straining.
Control
systems
The use of
computers is necessary for developing sophisticated control systems for smart
structures (e.g. robots) which can learn and take decisions. There are various
approaches to computational intelligence and evolutionary robotics. The
evolution of distributed intelligence
should be emphasized in this context; I shall discuss this in the next post.
Microelectromechanical
systems (MEMS)
MEMS are the current rage, as they involve a high
degree of miniaturization and integration of sensors, actuators, and control
systems comprising the smart structure or system. Miniaturization and
integration have many advantages: lower cost;
higher reliability; higher speed; and capability for a higher degree of complexity
and sophistication. Some authors equate smart structures with MEMS.
Modern applications of MEMS include those
in biomedical engineering, wireless communications, and data storage. Some of the more
integrated and complex applications are in microfluidics, aerospace, and biomedical
devices.
Silicon tops the list of
materials used for MEMS because of its favourable mechanical and
electrical properties, and also because of the already entrenched IC-chip
technology. More recently, there have been advances in the technology of using
multifunctional polymers for fabricating 3-dimensional MEMS (Varadan, Jiang and Varadan 2001). Organic-materials-based MEMS are also
conceivable now, after the invention of the organic thin-film transistor. In
the overall smart systems involving MEMS, there is also use for ceramics,
metals, and alloys, as also a number of ferroic or multiferroic materials.
I shall
discuss robots of the future in a separate post. Suffice it to say here that,
as Kurzweil predicts, we are approaching a 'technological singularity', beyond
which robots will overtake us in all abilities, and technological progress will
be so rapid as to outstrip our present ability to comprehend it. We shall transform
ourselves and augment our minds and bodies with genetic alterations, MEMS, NEMS (nanoelectromechanical systems), and true
machine intelligence. That would mark a complete blurring of the distinction
between the 'living' and the 'nonliving'.
Watch this
movie for a glimpse of what the future may be like:
No comments:
Post a Comment