NSF Graduate Fellow
Multiple Degree of Freedom Robotic Hand Design for Prosthetic Control Algorithm and Actuation Optimization Testing
Dr. Alba Perez
Masters of Science Mechanical Engineering
University Department and/or Lab:
College of engineering, mechanical department
My research focus is robotic kinematics and kinetic optimization.
Description of Research:
The major goal of my research is to develop a robotic hand that can be used as a testing device for the development of an improved prosthetic limb for persons with an amputation of the lower arm. Current prosthetics do not offer the level of dexterity that a human hand has. Part of the difficulty in achieving this level of dexterity in a prosthetic hand is a lack of degrees of freedom in current prosthetic designs compared to actual human hands. The test robot hand would be anthropomorphic in its design (similar degrees of freedom as a human hand and fully actuated).
In the future, control of prosthetics will be achieved using the myoelectric signals that exist in the remainder
of the limb. The nerve paths and signals that controlled the amputated limb remain up to the point of
amputation. Exploitation of these signals requires the relationship between the signals and the natural
postures and grip forces of the hand to be identified. Once the relationship is developed a control algorithm
can be developed to receive these myoelectric signals as inputs and then output the appropriate actuation signal
to the prosthetic hand. The robotic hand I am working on is a tool to test these control algorithms for accuracy
and to optimize the use of the limited energy that can be stored in a prosthetic hand power supply. The robotic
hand kinetic model would also allow the testing of various actuation technologies (pneumatic, electric, shape
memory alloy, artificial muscle).
In the 2007 FIRST challenge the students could earn up to 60 bonus points by lifting two other robots at the end of the match. My students made this a primary component of their competition strategy. One example of my research being integrated into my GK12 experience was helping the students analyze and choose a lifting method. There are many ways to accomplish the goal and they analyzed several of them using work and energy principles from physics. The students also had to do some kinematics to develop the linkage they used on the robot. They developed several solution methods including four bar linkages, folding ramps, and a piston lift mechanism for their machine and the other 2 machines. My engineering knowledge led me to believe that the four bar linkage was the optimal solution to the problem. I did not force the students to use the four bar linkage because I felt it was important for the students to make the decisions and build the machine they designed not the machine the mentor designed. The resulting analysis left the students in favor of a less complicated solution so they chose not to use a four bar linkage. The solution they used worked somewhat but not as well as the machines at the competition using four bar linkages for the lifting mechanism. The result was that the students were able to see the benefit of being willing to use a slightly more complicated design that is more controllable and more effective. The students also learned the importance of thorough design and mathematical proof of design before building. Next year they will be prepared to embrace a more difficult solution if the analysis indicates it is a more optimal solution.