Compliant Actuators Based on Electroactive Polymers
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features of an image on to the brain for "processing." A program with Uniax, Raytheon Infrared Center of Excellence (RIRCOE) and Computational Sensors Corporation is using EAPs to provide the analog processing by using the anisotropic conductivity property of polyaniline. Figure 1 shows how the conducting polymer is used to form a resistive layer which, upon closing the switches, connects capacitive elements holding charges Q(i). These charges represent the intensity of pixels in an image passed to the Figure 1 Analog Polymer processor from a charge coupled device (CCD) in an Processing imaging sensor. The amount of charge leakage between the elements of the sensor is determined by Sthe resistivity of the polymer layer and the time the
switches are held closed. The longer the closed time,
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the greater the blurring of the image, removing more
and more of the high spatial frequencies and thus
creating an analog low pass filter. It is also possible to form simple high pass and band pass filters by simple
modifications. Figure 2 illustrates the power of this
processing approach. In the figure the image was enhanced through the use of a set EAP image processing chips, which are performing local contrast control. The enhanced image allows for information to be pulled from the dark areas without loss of information from the remaining regions. This approach can be more than 10 times faster than digital processing and
has the scaling ability to process pixel arrays on
Figure 2: Affect of Blurrin g g
Oiginal Image
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the order of 2000x2000, and larger, with minimum increase in power and no loss of speed [2]. The next step is to learn how to produce controllable anisotropic properties in the polymer films to allow for selection of the directionality of the filtering, and ultimately to control the conductivity of the polymer in response to the target being sought. However, the simple near
term capability is more than sufficient to begin to apply this technology in defense applications
[3]. PROMISE OF COMPLIANT POLYMER ACTUATORS In this paper, the primary focus of discussion will be on three classes of compliant actuators: polymer gels, ionic polymer and conducting polymers. Given the number of actuators that exist, it is always important to ask why there is a need for another. From the authors' perspective, it is not simply the actuation potential of the materials, which arguably might be achievable by a number of alternative actuator designs, but rather that potential in concert with the compliant nature of polymers. A general view of the requirements of such actuators is to compare them with biological muscles as shown in Figure 3. From this graph it appears that the compliant actuators have the potential to match muscles, but have not yet the frequency. Other applications include microactuation in which the simplicity and flexibility of these actuators also show promise, but are not yet in use. Before undertaking a discussion of the con
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