Locomotion: Legs and Artificial Muscle. SUMMARY: Many labs at the forefront of robotic research, especially locomotive

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1 Topic: Locomotion, D1 Name: Gregg O Marr Date: March 2, 2000 Locomotion: Legs and Artificial Muscle SUMMARY: Many labs at the forefront of robotic research, especially locomotive research, are experimenting with leg-oriented motion. Using the natural bone structure of animals, scientists are building highly mobile robots. Other labs such as MIT, UNM, and JPL are researching the use of artificial muscle to produce simulated animal movement. The hardest part about designing a new way to do something is coming up with the initial idea or way to do it. So far in the field of robotics the designs have been big, bulky, and confined mobility. Scientists and engineers are now going to the place where the designs have been refined over thousands of years, nature. By studying the movement and anatomical structure of animals scientists will be able increase the mobility of robots. At MIT engineers are using the bone structure of a Troodon dinosaur from the cretatious period (Fig. 1)[]. By adapting the structure of the bird like dinosaur they were able to make Fig. 1 Troodon Dinosaur a two-legged robot that could walk and run (Fig. 2). Troody, as it is called, has 16 degrees of freedom, or locomotive parts that help in movement. These degrees have to be coordinated in order for the robot to obtain balance and therefore be able to move

2 effectively. From Troody the engineers learned vital information on what is necessary for a biped robot to move, and could then apply this knowledge towards the next advancement. Fig. 2 Troody M2 is a 3D bipedal walking robot being developed at MIT (Fig. 3). It is currently in the construction phase of its design. The engineers hope to be able to use the M2 to obtain the control model and algorithms needed for a bipedal robots []. One of the biggest difficulties to overcome is the stability or balance needed for a bipedal robot to move about. Humans use a liquid filled chamber within the inner ear, but robots do not have this benefit. Engineers must simulate the inner ear using bulky and power hunger gyroscopes and Fig. 3 Bipedal Robot sensing actuators, which can give the robots computer feedback as to what position it is in. The M2 is one of the closest robotic models to a highly mobile human, but there are others. The Honda 5 is a humanoid robot being developed by the Honda Corp.. (More will be added on the Honda robot later).

3 One of the main obstacles caused by current robotic designs is their power requirement. They have to power servomotors, actuators, pistons, computers, gyros, etc.. Currently, though, there is research being accomplished in the field of artificial muscles. If artificial, non-organic, muscles can be produced then I feel that some of the power required to move and control a robot will be eliminated. Animals do not require motors in their joints, to move the next appendage segments, they have muscles surrounding the joints that move counter to each other producing the mobility in the joint of biological muscle. NASA s JPL is currently researching technology to possibly achieve animal-like flexibility and manipulation. They are using electroactive polymers, which have a sizable contraction which a potenial is applied, they also produce a current when they are manually bent. The scientist and engineers at JPL believe that this technology could one day be used in the medical field to replace the damaged muscles of humans [7]. MIT is also researching artificial muscles using a polymer hydrogel of polyacrylonitrile. This type uses the ph of the solution it is immersed in to cause either a contraction or extention. As the solution becomes more acidic the muscle will contract, and visa versa when the solution becomes more basic. The only external power required is that needed to drive the solution injectors. In tests preformed on the muscle the researchers have been able to produce sizable muscle strength, by having the artificial muscle lift a hanging weight. One of the major difficulties with this type of artificial muscle is detioration of the muscle fiber cause by the acidic solutions [14]. The University if New Mexico is taking the science fiction approach to artificial muscle research, and is trying to remove the fiction part. Their artificial muscle designs are with

4 ionic polymer metal composite. They hope to reproduce a lot of the characteristics of biological muscles to produce flying and swimming robots. They are also trying to produce smart skin capable of control feedback [1]. Most of what I have researched in this paper is decades away from being true reality, but I propose is to take the first steps towards actually practically use of them. I believe that we should use a legged design for our mission to Mars for several reasons. First is that legged machines, like humans and other animals, are the most mobile excluding flying and swimming creatures. Legs will give the robot the ability to climb over and around obsticales. Second, by using multiple legs the robot will become a stable platform for other experimentation. Third, with use of or the testing of artificial muscle we can do away with current legged designing, which are heavily dependent on motors and actuators to produce the robot s locomotion. Finally, it will give us a chance to push current robotic designs into the future by atempting something that has never been done. I feel that our mission to Mars would be a great test-bed for artificial muscles.

5 I have not used all of the sources yet, and am not sure exactly which I used for this paper. Both of those will be sorted out in later revisions. [1] Artificial Muscles Research Institute, School of Engineering, School of Medicine, The University of New Mexico. Artificial Muscle Research Institute. 01 July February < [2] Center of Operation for FIeld RoBOtics Development (FIBO). Robotic News and Reports. 08 August February < [3] DLR. Institute of Robotics and Mechatronics. 10 February < [4] Fashoro, Bola. Biocontrol Research Issues in Use of Artificial Muscle Actuators for Medical Robot Devices: Nursing, Rehabilitation and Surgery. 10 February < [5] Gonzalez, Roger V. and Christopher Y. Lee. Smart Material as Artificial Muscles: A Quantitative Performance Study of Polyacrylonitrile Fibers February < [6] IoP. Sources Journals: Information. December February < [7] JPL. JPL Picture Archive. 08 February < [8] JPL. Nondestructive Evaluation (NDE) and Advanced Actuators (AA) Web-hub. 28 September February < [9] Kirkpatrick, Eric, Tina Lorek and Rick Nipper. Thermodynamic and Kinetic Considerations of Polymer Gels in Aqueous Conditions. 12 February < [10] KrisTech Robot Magazine. Building Better Bots February < [11] Lentz, Mathew. Chemomechanical energy conversion in polymers: PVA-PAA "artificial muscle". 11 February < [12] Max Planck Society for the Advancement of Science. Research News Release. 18 May February <

6 [13] McDermott, Shannon. NASA Tech Briefs Reader Form. 11 May February < [14] MIT. Artificial Muscle Project. 03 September February < [15] MIT. Research topics and projects for Ian Hunter. 07 October February < [16] Muller, Judy. "A New Stretch". 30 September February < [17] National Aeronautics And Space Administration. Robots in the News. 11 February < [18] Nature: Science update. Technology: Muscle Control. 27 September February < [19] Naval Command, Control & Ocean Surv Ctr (NCCOSC) RDT&E Division. Artificial Muscles for Robots. 09 February < [20] Robot Science and Technology. Robotics Info: News February < [21] Rutgers, The State University of New Jersey. A New Spherical Joint Actuated by Artificial Muscles. 07 February < [22] Scientific American. Artificial Muscles. 07 February < [23] The International Society for Optical Engineering. Smart Structures and Materials: Electro-active Polymer Actuators and Devices. 07 February < [24] UC Berkeley Mechanical Engineering. Biological Inspiration from the Poly- PEDAL Laboratory February < [25] Vanderbilt University School of Engineering. Intelligent Robotics Lab. 10 February <