Wednesday, 15 February 2012

BIOLOGICALLY INSPIRED INTELLIGENT ROBOTS USING ARTIFICIAL MUSCLE



BIOLOGICALLY INSPIRED INTELLIGENT ROBOTS USING ARTIFICIAL MUSCLE
                                                                        

Abstract:
                Artificial Intelligence is a branch of Science which deals with helping machines finds solutions to complex problems in a more human-like fashion. This generally involves borrowing characteristics from human intelligence, and applying them as algorithms in a computer friendly way. A more or less flexible or efficient approach can be taken depending on the requirements established, which influences how artificial the intelligent behavior appears.
Humans throughout history have always sought to mimic the appearance, mobility, functionality, intelligent operation, and thinking process of biological creatures. This field of biologically inspired technology, having the moniker biometrics, has evolved from making static copies of human and animals in the form of statues to the emergence of robots that operate with realistic appearance and behavior. This paper covers the current state-of-the-art and challenges to making biomimetic robots using artificial muscles.


Introduction:
             AI is generally associated with Computer Science, but it has many important links with other fields such as Math’s, Psychology, Cognition, Biology and Philosophy, among many others. The ability to combine knowledge from all these fields will ultimately benefit the progress in the quest of creating an intelligent artificial being. Advances in medicine have led to the
availability of artificial blood, replacement joints, heart valves, and heart-lung machines that are common implanted. device. Muscle is a critically needed organ and its availability in an artificial form for medical use can greatly contribute to the improvement of the quality of life of many humans. Thus these electroactive polymers (EAP) that are also known as artificial muscles can potentially address this need. These materials are human made actuators that have the closest operation similarity to biological muscles.

Motivation of Artificial Intelligence:
       Computers are fundamentally well suited to performing mechanical computations, using fixed programmed rules. This allows artificial machines to perform simple monotonous tasks efficiently and reliably, which humans are ill-suited to. For more complex problems, things get more difficult... Unlike humans, computers have trouble understanding specific situations, and adapting to new situations. Artificial Intelligence aims to improve machine behavior in tackling such complex tasks.

Technology:
                  There are many different approaches to Artificial Intelligence, some are obviously more suited than others in some cases, but any working alternative can be defended. Over the years, trends have emerged based on the state of mind of influential researchers, funding opportunities as well as available computer hardware.
              
Artificial life through robotics:
Laws of Robotics:
1. A robot may not injure a human being or, through inaction, allow a human being to come to harm.
2. A robot must obey the orders given it by human beings except where such orders would conflict with the first law.
3. A robot must protect its own existence as long as such protection does not conflict with the first or second law.
                          Robotics has been an evolution of the field of automation where there was a desire to emulate biologically inspired characteristics of manipulation and mobility. In recent years, significant advances have been made in robotics, artificial intelligence and others fields allowing to make sophisticate biologically inspired robots [Bar-Cohen and Brea zeal. Biologically inspired robotics is a subset of the interdisciplinary field of biomimetics. Technology progress resulted in machines that can recognize facial expressions, understand speech, and perform mobility very similar to living creatures including walking, hopping, and swimming. Further, advances in polymer sciences led to the emergence of artificial muscles using Electro active Polymer (EAP) materials that show functional characteristics remarkably similar to biological muscles.   Making creatures that behave like the biological model is a standard procedure for the animatronics industry that is quite well graphically animates the appearance and behavior of such creatures. However, engineering such biomimetic intelligent creatures as realistic robots is still challenge due to the need to physical and technological constraints.

Artificial muscles:
                  Muscles are the key to the mobility and manipulation capability of biological creatures and when creating biomimetic it is essential to create actuators that emulate muscles. The potential to make such actuators is increasingly becoming feasible with the emergence of the electro active polymers (EAP), which are also known as artificial muscles [Bar-Cohen, 2001]. These materials have functional similarities to biological muscles, including resilience, damage tolerance, and large actuation strains. Moreover, these materials can be used to make mechanical devices with no traditional components like gears, and bearings, which are responsible to their high costs, weight and premature failures. The large displacement that can be obtained with EAP using low mass, low power and, in some of these materials also low voltage, makes them attractive actuators. The capability of EAPs to emulate muscles offers robotic capabilities that have been in the realm of science fiction when relying on existing actuators.




FIGURE 1: A graphic illustration of the grand challenge for the development of EAP actuated robotics – an arm wrestling match against human.
             Unfortunately, the EAP materials that have been developed so far are still exhibiting low conversion efficiency, are not robust, and there are no standard commercial materials available for consideration in practical applications. In order to be able to take these materials from the development phase to application as effective actuators, there is a need for an established infrastructure. For this purpose, it is necessary to develop comprehensive understanding of EAP materials' behavior, as well as effective processing, shaping and characterization techniques. The technology of artificial muscles is still in its emerging stages but the increased resources, the growing number of investigators conducting research related to EAP, and the improved collaboration among developers, users, and sponsors are leading to a rapid progress.
            Robots, which could build other robots, tried to protect humans from everything until people could not do anything by themselves. Biggest supporters of AI research is military. One of the reasons is that in "...a nuclear age, a new generation of very intelligent computers incorporating AI could actually defend the country better, faster, and more rationally than humans.

Biometric robots using EAP:
                   Mimicking nature would significantly expand the functionality of robots allowing   performance of tasks that are currently impossible. As technology evolves, great number of biologically inspired robots actuated by EAP materials emulating biological creatures is expected to emerge. The challenges to making such robots can be seen graphically in Figure 2 where humanlike and dog-like robots are shown to hop and express joy. Both tasks are easy for humans and dogs to do but are extremely complex to perform by existing robots.

FIGURE 2: Making a joyfully hopping human-like and dog-like robots actuated by EAP materials are great challenges for biomimetic robots






















FIGURE 3: An android head and a robotic hand that are serving as biomimetic platforms for the development of artificial muscles.



Categories of EAP:
                         EAP can be divided into two major categories based on their activation mechanism including ionic and electronic. The electronic EAP are driven by Coulomb forces and they include: Dielectric EAP (shown in Fig.4a), Electrostrictive Graft Elastomers, Electrostrictive Paper, Electro-Viscoelastic Elastomers, Ferroelectric Polymers and Liquid Crystal Elastomers (LCE). This type of EAP materials can be made to hold the induced displacement while activated under a DC voltage, allowing them to be considered forrobotic applications. These materials have a greater mechanical energy density and they can be operated in
air with no major constraints. However, the electronic EAP require a high activation fields (>30-V/μm) that may be close to the breakdown level. In contrast to the electronic EAP, ionic EAP are materials that involve
mobility or diffusion of ions and they consist of two electrodes and an electrolyte. The activation of the ionic EAP can be made by as low as 1-2 Volts and mostly a bending displacement is induced. The ionic
EAP include Carbon Nanotubes (CNT), Conductive Polymers (CP), Electro Rheological Fluids (ERF), Ionic Polymer Gels (IPG), and Ionic Polymer Metallic Composite (IPMC) (shown in Fig.4b). Their disadvantages are the need to maintain wetness and they pose difficulties to sustain constant displacement under activation of a DC voltage (except for conductive polymers).
a. Dielectric EAP in relaxed (top) and
activated states (bottom)
b. IPMC in relaxed (left) and activated states (right)
Examples of EAP materials in relaxed and activated states.
         The induced displacement of both the electronic and ionic EAP materials can be designed geometrically to bend, stretch or contract. Any of the existing EAP materials can be made to bend with a significant bending response, offering an actuator with an easy to see reaction.

FIGURE4a. Dielectric EAP in relaxed (top) and activated states (bottom).

















FIGURE4b. IPMC in relaxed (left) and activated states (right)

Making Robots Actuated by EAP:

         Biomimetic intelligent creatures as realistic robots were a significant challenge due to the physical and technological constraints and shortcomings of existing technology. Making such robots that can hop and land safely without risking damage to the mechanism, or making body and facial expression of joy and excitement are very easy tasks for human and animals to do but extremely complex to engineer. The use of artificial intelligence, effective artificial muscles and other biomimetic technologies are expected to make the possibility of realistically looking and behaving robots into more practical engineering models. To promote the development of effective EAP actuators, which could impact future robotics, toys and animatronics, two test-bed platforms were developed.  The conventional electric motors are producing the required deformations to make relevant facial expressions of the Android. Once effective EAP materials are chosen, they will be modelled into the control system in terms of surface shape modifications and control instructions for the creation of the desired facial expressions. Further, the robotic hand is equipped with tandems and sensors for the operation of the various joints mimicking human hand. The index finger of this hand is currently being driven by conventional motors in order to establish a baseline and they would be substituted by EAP when such materials are developed as effective actuators. The growing availability of EAP materials that exhibit high actuation displacements and forces is opening new avenues to bioengineering in terms of medical devices and assistance to humans in overcoming different forms of disability. Areas that are being considered include an angioplasty steering mechanism, and rehabilitation robotics. For the latter, exoskeleton structures are being considered to augment the mobility and functionalities of patients with weak muscles.

Remote presence via haptic interfaces:

                Remotely operated robots and simulators that involve virtual reality and the ability to “feel” remote or virtual environment are highly attractive and offer unmatched capabilities [Chapter 4 in Bar-Cohen and Brea zeal, 2003]. To address this need, the engineering community are developing haptic (tactile and force) feedback systems  that  are allowing users to immerse themselves in the display medium while  being connected thru haptic and tactile interfaces to allow them to perform telepresence and “feel" at the level of their fingers and toes. Recently, the potential of making such a capability with high resolution and small workspace was enabled with the novel MEMICA system (Mechanical Mirroring using Controlled stiffness and Actuators).


Biologically inspired robots:

                  The evolution in capabilities that are inspired by biology has increased to a level where more sophisticated and demanding fields, such as space science, are considering the use of such robots. At JPL, a six-legged robot is currently being developed for consideration in future missions to such planets as Mars. Such robots include the LEMUR (Limbed Excursion Mobile Utility Robot). This type of robot would potentially perform mobility in complex terrains, sample acquisition and analysis, and many other functions that are attributed to legged animals including grasping and object manipulation. This evolution may potentially lead to the use of life-like robots in future NASA missions that involve landing on various planets including Mars.
                The details of such future missions will be designed as a plot, commonly used in entertainment shows rather than conventional mission plans of a rover moving in a terrain and performing simple autonomous tasks. Equipped with multifunctional tools and multiple cameras, the LEMUR robots are intended to inspect and maintain installations beyond humanity's easy reach in space with the ability to operate in harsh planetary environments that are hazardous to human. This spider looking robot has 6 legs, each of which has interchangeable end-effectors to perform the required mission (see Figure 4). The axis symmetric layout is a lot like a starfish or octopus, and it has a panning camera system that allows omni-directional movement and manipulation operations.

FIGURE 4: A new class of multi-limbed robots called LEMUR (Limbed Excursion Mobile Utility Robot) is under development at JPL

   
Robots as part of the human society:

                 As robots are getting the appearance and functionalities of humans and animals there is a growing need to make them interact and communicate as a sociable partner rather than a tool. This trend is requiring that robots would be able to communicate, cooperate, and learn from people in familiar human-oriented terms. Such a capability poses new challenges and motivates new domestic, entertainment, educational, and health related applications for robots that play a part in our daily lives. It requires obeying a wide range of social rules and learned behaviors that guide the interactions with, and attitudes toward, interactive technologies. Such robots are increasingly emerging and one example of such a robot is the Kismet that was developed by Breazeal [2002]. Kismet perceives a variety of natural social cues from visual and auditory channels, and delivers social signals to people through gaze direction, facial expression, body posture, and vocalizations.
           Natural language processing will provide important services for people who speak different languages. If a computer is able to understand natural languages, it will also be able to translate from one language to another. The "universal translator" widely used Star Trek may actually become a reality! This, of course, also includes voice recognition, or speech recognition.
              
Future of Artificial Intelligence:

            In the near future things such as object recognition, voice recognition, and natural language understanding will be a reality. Will there be systems so advanced that they have to be given rights similar to those of humans? Probably not in the foreseeable future. But maybe in a little more than half a century, if the humanity survives that long, such machines may very well develop.


 Advantage Of Future Artificial
  Intelligence:

       They will probably be increasingly used in the field of medicine. Knowledge based expert system, which can cross-reference symptoms and diseases will greatly improve the accuracy of diagnostics. Object recognition will also be a great aid to doctors. Along with images from cats cans or X-ray machines, they will be able to get preliminary analysis of those images. This of course will be possible only if people solve legal questions that arise by giving power to a machine to control or influence the health of a human.
              Idea of Artificial Intelligence is being replaced by artificial life or anything with a form or body.
  • The consensus among scientists is that a requirement for life is that it has an embodiment in some physical form, but this will change. Programs may not fit this requirement for life yet. 

Applications:

        The potential applications of Artificial Intelligence are abundant. They stretch from the military for autonomous control and target identification, to the entertainment industry for computer games and robotic pets. And also big establishments dealing with huge amounts of information such as hospitals, banks and insurances, who can use AI to predict customer behavior and detect trends.

Suggestion And Success:

                    Use of EAP liquid, called Electro-Rheological Fluid (ERF), which becomes viscous under electro-activation we could design miniature Electrically Controlled Stiffness (ECS) elements and actuators. Using this system, the feeling of the stiffness and forces applied at remote or virtual environments will be reflected to the users via proportional changes in ERF viscosity.
                      The success in developing EAP actuated robotic arms that can win a wrestling match with human opponent can greatly
benefit from the development by neurologists. Using such a capability to control prosthetics which would require feedback to allow the human operator to “feel” the environment around the artificial limbs. Such feedback can be provided with the aid of tactile sensors, haptic devices, and other interfaces. Besides providing feedback, sensors will be needed to allow the users to monitor the prosthetics from potential damage (heat, pressure, impact, etc.) just as we are doing with biological limbs. The development of EAPmaterials that can provide tactile sensing


CONCLUSION:

                     Using effective EAP actuators
would immensely expand the collection and functionality of the actuators that are currently available as well as enable making artificial organs. The prospect of developing technology that would enable making “bionic” humans with artificial muscles. These man-made materials operate as actuators with the closest functional similarity to biological muscles including resilience, quiet operation, damage tolerance, and large actuation strains (stretching, contracting or bending).Visco-elastic EAP materials can provide more lifelike aesthetics, vibration and shock dampening, and more flexible actuator important addition to this capability can be the application of telepresence combined with virtual reality using haptic interfaces. Thus more intelligent biomimetics to improve our lives can be made in response to the wear inspired by the biology which will increasingly find challenges to the implementations.


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